Elastic Nonwovens and Application Areas

Deniz Duran1, Hatice Aktekeli2

1Ege University – Faculty of Engineering – Textile Engineering Department.35100 Bornova, İzmir/TÜRKİYE

2Ege University – Faculty of Engineering – Textile Engineering Department., 35100 Bornova, İzmir/TÜRKİYE

deniz.duran@ege.edu.tr

 

Elastic Nonwovens and Application Areas

Abstract

Nonwoven surfaces have become one of the fastest-growing textile branches in recent years, which significantly stems from the practical use of disposable products, and awareness on its importance in terms of hygiene. It is desired that nonwoven surfaces used in some areas should have high flexibility in terms of comfort and ease of use and maintain this flexibility. For this reason, there is a day-by-day increasing interest in flexible nonwoven surfaces. In this study, the definition of flexible nonwoven surfaces, methods for obtaining flexible nonwoven surfaces and their application areas are specified.

Key Words:Nonwoven surface; Flexible nonwoven surface; Elastic nonwovens; Thermoplastic elastomer.

  1. INTRODUCTION

In the globalizing world, it has become a necessity to manufacture innovative products for the development of our industry and economy. Cost and speed are two of the most important factors in the production phase. In this area, nonwoven surfaces allow us to find fast, easy, effective and economical solutions to problems with their wide use at every stage of modern life. Nonwoven surface products offer manufacturers the advantage of simplicity in the manufacturing process and the ability to apply desired qualities (absorbent/retaining, soft/stretched etc.) to nonwoven surface products as they require a manufacturing process simpler than the conventional textile fabrics. [1]

Nonwoven surface products, which are manufactured in a fashion both faster and cheaper, are being used more ever day in new areas. Especially the increase in the practical use and usage habits of disposable products allow mobility in the nonwoven surface industry and caused the market to grow. When examining Turkey’s 22 main product groups in the technical textiles export, it is observed that nonwoven surface products constitute the most exported product groups of Turkey’s technical textile exports. Nonwoven surface products which form 30,9% of Turkey’s total exports of technical textiles (nonwoven) exports in 2017 were valued at approximately 479 million dollars, increasing by 9,5%. When examining the technical textiles imports in Turkey’s 22 basic product groups, it is seen that nonwoven surface products are the second imported products with 11,5% after glas fiber and their products. In 2017, imports of nonwoven surface products increased by 12% to approximately $ 220 million. [1, 2]

Demand for nonwoven surface products is increasing day by day and it is predicted that over the coming years the numbers will exceed today’s value. [3]

In the field of nonwoven products, products with a high degree of flexibility at low cost is constantly needed. these nonwoven products are being produced especially for disposable diapers, sick cloths and also areas such as lining, and filtration. They are preferred for flexibility, softness, durability, good stretch-backing properties and high tearing elongation features. [4]

There are also literature studies on elastic nonwovens –an important issue in innovations which have taken place in the nonwoven surface area in recent years.

In a study by Srinivas et al., they treated polypropylene homopolymer and thermoplastic elastomer (TPE) under the same conditions and observed a marked difference in elongation properties. The polypropylene homopolymer is only 35% elongated, while the surfaces produced with thermoplastic elastomer (TPE) can be elongated up to 360%. According to Srinivas et al., molecular parameters such as molecular weight, molecular weight distribution, composition, melting temperature and crystallinity grade affect the elastic behavior of the polymer. The elasticity of the web is related to the molecular weight and the specific elastomeric composition. As expected, low crystallinity requires high elasticity. As the level of crystallinity increases, the mechanical behavior of the polymer changes from an elastomeric character to a plastic one.[5]

Zhao states in his work that the industry focused on the meltblown process to develop unique fiber and surface properties using special polymers, and that many factors are needed to develop high-value meltblown products, among which polymer properties, targeted areas of use of the product, and properties and capabilities of meltblown equipment are mentioned. Polypropylene nonwovens produced with the meltblown method have attracted more attention in areas such as hygiene, medical and personal care products with high flexibility of nonwovens made of elastic raw material, although they may have one-sided stretching properties. [6]

Dharmarajan et al., used the meltblown method in their work for surface preparation and have blended thermoplastic elastomer (TPE) and classical polypropylene on some samples. Inclusion of polypropylene thermoplastic elastomer increases the elongation of the nonwoven surface. Surface elasticity increases with increasing TPE ratio. Even 30% weight of TPE content makes the surface softer and drapery than polypropylene. In the light of these results, they have stated that meltblown elastic nonwovens containing TPE polymers have offered a new elastomeric product, which can be used in hygiene, personal care, medicine and industrial applications. [7]

Li et al. used the thermoplastic elastomer in their study to produce a surface with the meltblown method. According to Li et al., the elastic meltblown nonwovens have incomparable advantages over ordinary meltblown surface. Therefore, they have stated that this material is the new favorite in the nonwoven industry and elastic nonwovens produced with the meltblown method using TPE are high elastic materials which can solve the low elasticity problem of the conventional nonwovens. [8]

 

  1. ELASTIC NONWOVENS

Materials imposed to deformeation under pressure (elongation/ change of form) and reverted to its original state when unpressured are called elastic materials, and such deformations are called as elastic deformation. Mechanical creep (almost) does not occur. [9]

Elastic nonwovens are products, which exhibit superior elongation/reversibility compared to conventional nonwoven surfaces. While the elasticity on the conventional nonwoven surfaces is around 30%, it can reach 300% on elastic nonwoven surfaces. [5]

The limited resilience of the surfaces produced using conventional synthetic raw materials causes limitations in their usage and application. On surfaces produced using special thermoplastic elastomers (TPE), this problem can be avoided and highly elastic surfaces can be created (Figure 1). This will allow limitations and combine with the advantages of meltblown method to find a more common and convenient area of use. [6]

Elastic nonwoven surface before stretching     Elastic nonwoven surface after stretching

Figure 1. Elastic nonwoven surface before and after stretching [10]

2.1. Elastic Nonwoven Production Methods

Elasticity can be achieved in the texture in different ways. The most important ones are:

2.1.1. Customized voluminous design for nonwoven web structure

Voluminous web structure can be achieved by needle method in particular. In this method, the fibers are laid smoothly on top of each other to form a surface and fixed with special needles to form a web surface. However, the surfaces produced in this method can be too thick and show little flexibility.

2.1.2. Achieving elasticity in materials using crimp fibers

As the crimp fibers on surfaces produced by using crimp fibers are opened under pressure, the surface will stretch and revert to its original state when unpressured. However, the flexibility obtained by this method is very insufficient.

2.1.3. Production using special meltblown method with raw materials

The meltblown method does not require a special preparation process to form the surface, nor does it need to prepare any solution to draw fibers. Fibers are taken directly from the polymers.

In the meltblown method, the special thermoplastic material (TPE) is heated in the extruder and melted up to the temperature and viscosity to provide the fiber formation. The melt is sprayed through the nozzle holes at high speed with a flow of hot air, and these micro-sized fibers become cool and solidify as they move towards the pick-up cylinder. The solidified fibers randomly orientated in the picking cylinder create the elastic nonwoven surface. [11]

2.1.4. Production with finishing operations such as coating

The nonwoven surface is created by covering one or both sides of the surface with a chemical substance. The chemical materials are applied on the surface in the form of powder, paste or foam to form a film layer on the ground. [12]

2.1.5. Production with composite technology

Composite materials are a group of material, which are created by bringing together at least two different materials for a specific purpose. The purpose in this three-dimensional assembling feature is to create a feature, which is not present in any of the components alone. In other words, it is aimed to produce a material with superior properties for the desired components. [13]

The elasticity of the web produced with the first two methods is limited while they have excessive thickness. Flexibility of the web obtained with the coating method is not at the desired level. It has been seen that problems are solved in the web produced using TPE chips. [8]

  1. THERMOPLASTIC ELASTOMER (TPE) – RAW MATERIAL FOR ELASTIC NONWOVENS

Crosslinked rubbery polymers, or rubbery webbands, which exhibit very high elongation under tensile force and revert to their original initial length when the force is lifted, are called elastomers. The most commonly used and known elastomers are polyisoprene (or natural rubber), polybutadiene, polyisobutylene and polyurethane.

Thermoplastic elastomers (TPE’s) are polymers that exhibit elastomer behaviors, even though they do not have chemical cross-links between their molecules.

The physical cross-links in the TPEs constitute the webbing structure by interlocking the flexible molecules together. They can be processed as thermoplastics at high temperatures and exhibit elastomeric behavior when cooled (Figure 2). The transition from thermoplastic behavior to elastomeric behavior is completely reversed, i.e. unlike conventional elastomers, thermoplastic elastomers can be processed repeatedly, so they can be recycled. [14]

Thermoplastic elastomers contain two distinct phases in their texture:

  • Elastomeric phase with rubber features
  • Rigid phase with thermoplastic features. [14]

Figure 2. Temperature change in the thermoplastic elastomer structure [15]

 

  1. APPLICATION AREAS OF ELASTIC NONWOVENS

Elastic nonwovens find use in the fields of filtration, medicine and hygiene as soft protective cap, lining and gloves.

  • Medicine and Hygiene

Research and development studies in both fiber types, in which materials used in medicine and hygiene applications are produced, and in the production techniques of such materials, cause the increase in the use of medicine and hygiene textiles in all technical textiles every day. [16]

The fastest developments in medicine and hygiene textiles have occurred after the discovery of synthetic fibers. Rapid developments have been achieved with the invention nonwoven products in the 1960s, and improving a 56% reduction in the risk of infection transmission with the use of disposable products in 1985. [17]

 

The most important use of nonwovens is the hygiene industry. In a report published by  EDANA – European Nonwoven Producers Association, 35 billion products have been sold in the European hygiene market in 1997, 90 billion in 2004 and 211 billion in 2013 (Figure 3). [18]

Figure 3. The number of nonwoven products sold in the European hygiene market

 

Especially the elastic nonwoven medical bandages exhibit excellent stretching, wrap the wound well, hel healing quickly and leave only a small trace. Patients using them feel comfortable and at ease.

Its porous structure allows skin moisture to penetrate and the skin to breathe. Its elastic structure easily conforms to body folds and joints.

 

In addition, these elastic nonwoven materials also find use in areas such as patients and diapers (Fig. 4), menstrual pads, and in hospital equipment such as surgical disposals and gowns that require disposability, non-slipperiness and elasticity. [8]

Figure 4. Patient diaper with elastic nonwoven materials [19]

 

  • Soft Stretching Caps

It significantly increases comfort, safety and work efficiency for workers. It is non-irritant, soft-textured and has high tensile strength with low shrinkage force. They have a breathable structure for perfect comfort and ease. It provides excellent barrier treatment and filtration performance (Figure 5).

  • For use in construction, mining, health and waste management to prevent dirt, dust, airborne particles and airborne liquids,
  • For protection against dust, bacteria and harmful chemicals in laboratories and factories,
 

Figure 5. Caps with elastic nonwoven material [10]

  • For shielding against outdoor activities, wind and rain,
  • In order to provide good bacteria and particulate filtration in medical use,
  • It can be used for undercoating in hard caps, emergency respiratory masks and other face protection equipment. [10]

Undercoating

A study conducted by researchers at the University of Tennessee, USA, of Materials Science and Engineering reveals that the use of elastic nonwoven as a primer in military apparel shows better filtering features against chemical and biological threats.

Also, undercoating made of such structures in sportswear and women’s clothing helps show the body better. [8]

  • Filtration

These structures, produced using microfiber fibers, have great market share thanks to their superior filtration performance.

These elastic nonwovens, which can also be used in production of masks, provide protection against gas, dust and bacteria in the medical field by preventing harmful granules (Figure 6). Also these filters can be used in AC units, automobiles and engines[8].

 

Figure 6. Mask with elastic nonwoven material [20]

  • Gloves

Elastic nonwoven gloves are used in pharmaceutical factories and research laboratories, where high protection is required thanks to their excellent stretching, absorbing and filtering features. [8]

  1. CONCLUSION

Elastic nonwovens provide balanced mechanical features thanks to better elongation for increased flexibility, higher impact strength, higher melt flow rate for easier machining, lower cost and higher performance in comparison with conventional nonwovens. Especially on machine applications, they exhibit better breaking resilience and tearing prolongation. [21]

Thanks to these features, the application area for elastic nonwovens is growing day by day. The studies conducted in this area is also increasing every day. Interest and researches in the elastic nonwovens, which is considered to be one of the important branches in nonwoven industry, are increasing thanks to the improvements in living standards rising with awareness on the importance of  disposable products especialy for health, advanced level of improved product performances and the R&D activities conducted by the leading companies to grow their market domination.

RESOURCES

[1]KDR Tekstil, http://www.kdrtekstil.com.tr/bilgi-3.php (Erişim tarihi: 13.05.2016)

[2]ITKIB, Teknik Tekstil Sektörüne İlişkin Güncel Bilgiler, Mart 2015, http://www.itkib.org.tr/ihracat/DisTicaretBilgileri/raporlar/dosyalar/2015/TEKNIK_TEKSTIL_SEKTORUNE_ILISKIN_GUNCEL_BILGILER-MART_2015.pdf (Erişim tarihi: 05.04.2016)

[3]Textotex, Hijyen Uygulamalarında Nonwoven Teknolojisi, http://www.textotex.com/haber/tekniktekstil/hijyen-uygulamalarinda-nonwoven-teknolojisi.html (Erişim tarihi: 03.11.2015)

[4]Boggs L., Elastic polyetherester nonwoven web, 1987, US 4707398 A.

[5]Srinivas, S., Cheng, C. Y., Dharmarajan, N. and Racine G., 2005, “Elastic Nonwoven Fabrics from Polyolefin Elastomers”, http://faculty.mu.edu.sa/public/uploads/1426341765.4035Elastic_Nonwoven_Fabrics.pdf (Erişim tarihi: 10.10.2015)

[6]Zhou R., 2004, Stretching the Value of Melt Blown with Cellulose Microfiber and Elastic Resins, Biax Fiberfilm Corporation, 13p.

[7]Dharmarajan R., Kacker S., Gallez V., Westwood A.D. and Cheng C.Y., Meltblown Elastic Nonwovens from Specialty Polyolefin Elastomers, ExxonMobil Chemical Company, 3p.

[8]Li L., Zhang J., Li S. and Qian X., 2011, Research Progress of Elastic Nonwovens with Meltblown Technology, Advanced Materials Research, Vols. 332-334, 1247-1252pp.

[9]Yalçınkaya E., Elastisite Teorisi(Stress-Strain) Gerilme-Deformasyon İlişkisi, https://iujfk.files.wordpress.com/2013/09/3-ders-elastisite.pdf, (Erişim Tarihi: 28.04.2016)

[10]Vitaflex, http://vitaflexllc.com/index.html, (Erişim Tarihi: 19.10.2015)

[11]Atul Dahiya, M., Kamath, G. and  Raghavendra, R., 2004, Meltblown Technology, http://www.engr.utk.edu/mse/Textiles/Melt%20Blown%20Technology.htm (Erişim tarihi: 13.10.2015)

[12]Bulut Y., Sülar V., 2008, Kaplama veya Laminasyon Teknikleri ile Üretilen Kumaşların Genel Özellikleri ve Performans Testleri, Tekstil ve Mühendis, Sayı:70-71, 5-16.

[13]Kompozit Malzemeler Hakkkında Her şey, http://www.bilgiustam.com/kompozit-malzemeler-hakkinda-hersey/(Erişim Tarihi: 21.09.2016)

[14]Esen, M., “Termoplastik Elastomerler”, http://www.kimyam.net/2012/09/elastomer-nedir.html (Erişim tarihi: 26.10.2015)

[15]Deniz V., Karakaya N., Karaağaç B., Aytaç A. ve Gümüş S., 2008, Stirenik Termoplastik Elastomer Malzeme Geliştirilmesi, TÜBİTAK MAG Proje 107M412, 58s.

[16]Ilgaz S., Duran D., Mecit D., Bayraktar G., Gülümser T. ve Tarakçıoğlu I., Medikal Tekstiller, Tekstil Teknik Dergisi, Şubat 2007, Yıl-23, Sayı 265, 138-162.

[17]Güney S., 2009, Peristaltik Hareket Sağlayan Tıbbi Tekstil Materyalinin Geliştirilmesi ve Bilgisayarlı Kontrolü, Süleyman Demirel Üniversitesi, Yüksek Lisans Tezi, Isparta, 70s.

[18]Anonim, 2010, Nonwoven Tekniği ile Hijyenik, http://www.bilgilerforumu.com/forum/konu/nonwoven-teknigi-ile-hijyenik.630333/,  (Erişim Tarihi: 10.02.2016)

[19]Can Kimya, http://www.tamtut.com/tr/fullbond-urunler/20/yetiskin-ve-hasta-bezi-hotmelt-yapistiricilari, (Erişim Tarihi: 30.09.2016)

[20]ASM Medical, http://www.asmmedical.com/cat/aile-hekimligi-sarf-malzemeleri/sayfa/2, (Erişim Tarihi: 30.09.2016)

[21]ExxonMobil Chemical, 2010, Vistamaxx™ propylene-based elastomer,

http://www.ktron.com/News/Seminars/Plastics/Houston/Vistamaxx_-_PBE-An_innovation_for_the_masterbatch_industry.cfm, (Erişim Tarihi: 24.09.2015)

Investigation of Mechanical And Morphological Performance Properties of Cotton Fabric Coated With Copper Oxide Particles

Aslıhan Koruyucu, A.Özgür Ağırgan Namık Kemal University; Çorlu Engineering Faculty, Textile Engineering Department, Çorlu, Tekirdağ, Turkey

 

Abstract
Gaining antibacterial protection in fabrics is one of the increasingly important functional properties. In this study, the development of fabrics for specific application areas was foreseen using copper oxide, which is the center of attention of the whole world because of its economic status. The purpose of this article is to produce cotton fabrics with enhanced antibacterial functions using copper oxide particles and It is planned to investigate the possibilities of using these fabrics in the technical textiles field. Thus, it is aimed to reduce the microbial infections originating from the surfaces that people have contacted many times during the day. In this article, when different particulate copper oxide chemical substances applied to the textile industry for antibacterial purposes are used changes in the performance characteristics of cotton fabrics have been investigated. For this purpose, cotton fabrics are coated with antibacterial Cu (I) O, Cu (II) O particles and isocyanate and glycidimethacrylate structures with cross-linkers. The selection of copper oxide particles as antibacterial was made by examining previous studies. Another benefit of the use of copper oxide particles in the presence of an antibacterial property it is an attempt to form an alternative to the antibacterial property provided by silver, zinc oxide and titanium oxide in previous studies. Besides, the silver used is expensive compared to other used antibacterial materials is an important problem. Zhang et al.(2008) refered to strong evidence that silver ions show cytoxidic and genotoxic effects for high organisms (including humans). After coating with Cu(I)O and Cu(II)O antibacterial agent, the tensile strength properties of cotton fabric samples increased and mechanical effects after coating with isocyanate crosslinker because it damages the fabric structure reduction in tear strength was achieved. In the FTIR spectra of the fabric after coating, the new bands would be a sign of a modification due to coating processes are occurred.

1.Introduction
Substances or environments that inhibit bacterial growth and inhibit are defined as antibacterial. Due to the harmful and bad smell of the bacteria; the use of antibacterial materials, especially in garments and fabrics , are becoming even more important. Antimicrobial agents are defined as those that kill microorganisms such as bacteria, mold, yeast and fungi. On the other hand, it is also defined as a natural, synthetic or semisynthetic chemical that inhibits growth, proliferation or activity. The importance of the antibacterial based functional textiles is given below: In the study of transferring silver nanoparticles from antibacterial fabric to artificial sweat are connected to on amount of silver transferred artificial sweat to the initial coating, fabric quality, pH and artificial sweat formulation. In this study, the effects of silver molecules on human health were examined(1). Silver nanoparticles, silver ions exhibit bacteriocidal action when are used alone or in various combinations. By increasing the permeability of the bacterial cell membrane, the energy requirement of the cell is triggered. At this point, there is a flow of phosphate, cellular contents leak, and DNA proliferation is interrupted (2). Kathirvelu et al. (2008) investigated the self-cleaning, antibacterial and UV protection functions of the fabrics coated with TiO2 NPs at different temperatures and concentrations produced with a hydrolytic reaction starting with HNO3 and titanium tetrachloride. They found that there was no change in the self-cleaning activities of the prepared sample fabrics. However, they found that the UV protection effect was higher in PES / Cotton fabrics, woven fabrics and fabrics coated with small NPs. It was determined that woven fabrics, 100% cotton fabrics and fabrics coated with small NPs exhibited antibacterial properties at a higher level. When examined for all three functions, it was observed that the use of TiO2 in coatings made with ZnO and TiO2 is more advantageous than the use of ZnO (3). In previous studies; There is strong evidence that silver ions show cytoxidic and genotoxic effects for high organisms (including humans) (4). Performance changes and antimicrobial activity amounts of chemicals known to antimicrobial activity such as silver, triclosan, dichlorophenol, quarternary ammonium and chitosan, which are frequently used in the industry, on 100% cotton fabrics have been compared comparatively. In working with this, however, the antimicrobial fabrics produced with the specified chemicals, antimicrobial performance values after 1, 5, 10, and 20 washings were compared (5). In previous studies; antibacterial agents bonded with aluminum or titanium compounds, antibacterial surfaces treated with cotton fabrics. One of the metal compounds, oxytetracycline, tetracycline, pyrithione, or the antibacterial agent to which the process is applied by passing the same through different baths, is effective against Staphylococcus aureus bacteria. Some of the tetracycline treated fabrics continue to exhibit antibacterial activity even after 20 washes. Because of some problems encountered during the application of titanium compounds, the antibacterial activities of the aluminum compounds have been found to be more satisfactory (6).

2. Materials and Methods
In the experiments; The cotton fabric used as the material was supplied by Bossa. In the experiments; The characteristics of cotton fiber as material are given in the Table. In the study, copper(I) oxide and copper (II) oxide were used as nano and micro particle size materials in order to provide antibacterial property.

ekran-resmi-2016-12-09-12-21-16
In this study, as coating chemicals; two different polyurethane binders, the cross-linker in two different structures, a antifoaming for cutting the foam formed in the coating path, an emulsion to provide homogeneous distribution of copper oxide particles in the path, dispersion material; a thickener was used to adjust the flow of the path. One of the binders is of an aliphatic polyester polyurethane structure, the another one is; the coating should contain a polysiloxane compound to increase the resistance to hard water salts and washing of the path. In this study; for the purpose of improving the activity of antibacterial treated cotton fabrics, crosslinkers were used in the coating recipe for isocyanate and glidimethacrylate structures. Antibacterial finish treatment was applied to the fabric samples according to the knife-over-roller coating method. Physical tests such as breaking strength, tear strength and abrasion resistance were applied to the fabric samples after the coating process. Besides, SEM image for the purpose of examining the morphological changes occurring on the fabric sample surfaces after coating, FTIR analysis was carried out to examine the changes in bond structure of the post-coating fabrics. Physical tests applied to sample fabrics are given in the table.

ekran-resmi-2016-12-09-12-22-30
3. Conclusions and Discussion 3.1. Breaking, tearing and abrasion resistance properties of treated fabrics
It is thought that antibacterial finishing will cause a change in the strength of the positive or negative fabric breaking. The results of the tensile strength test for cotton fabrics are given in Figure 3.1. Based on the weight of the specimen, the pre-tension applied during the test was set at 5N. As shown in the figure, Cu (II) O in nano particle size was found to cause the greatest strength increase in the warp and weft direction of the coating with glidimethacrylate crosslinker.

By applying glycidemethacrylate as a cross-linker to the cotton fabric, there is more cross-linking between the fiber and the coating. Since this gives extra strength to the coated cotton fabric, no overall loss of tear strength was observed. As a result; the chemical substances containing the isocyanate group in the coating path, oxide release the CO2 gas during reactions with water, the resulting pressure of this carbon dioxide gas causes the foam to form in the polymer, which leads to reduced cross-linking in the coating and reduces the breaking strength of the coating.

abric
Tear strength measurements were made in the weft and warp directions on each fabric sample, the percent change values of the tear strength according to the control groups are calculated and shown in Figure 3.2. Tearing in the weft direction, breaking of the warp fibers, while tearing in the warp direction corresponds to the break of the weft fibers. The highest strength loss was observed for the 1st fabric and 2nd micro particle size after coating with Cu(I)O, Cu(II)O antibacterial agent and isocyanate crosslinker 29,26% and 20,15% respectively. Particle size is constant; the highest strength loss was observed after coating with the isocyanate cross-linker. Mechanical effects after coating with antibacterial agent particle size and isocyanate cross-linker, resulting in loss of tear strength as it damages the fabric structure. The highest strength loss was observed in the first and second cumulative microparticle sizes after coating with Cu (I) O and Cu (II) O antibacterial agent and isocyanate crosslinker were calculated as 31.53% and 19.66% respectively. Particle size is constant; maximum loss of strength was observed after coating with isocyanate cross-linker. Mechanical effects after coating with antibacterial agent particle size and isocyanate cross-linker resulting in loss of tear strength as it damages the fabric structure.

fabric

ekran-resmi-2016-12-09-12-29-453.2. SEM properties of treated fabrics
In the figure, SEM images of micro and pure Cu (I) O applied fabrics are given. Polyurethane binders used in coating process, blocked isocyanate and cross-linkers in glycidmethacrylate structure has been observed that polymerization is carried out with the surface.

3.3. FTIR properties of treated fabrics
FT-IR analysis was used to investigate the presence of the chemical bonds in the coating path structure in the applied cotton. The FT-IR spectra of the cotton fabrics pretreated in the formulations were given in blue color. The characteristic peaks of the cotton fabrics pretreated in the spectra are summarized in Table 4.1. Pre-treatment followed by micro Cu (I) O and two ekran-resmi-2016-12-09-12-30-25different crosslinkers FTIR spectra of the antibacterial coated cotton fabric are shown in Figure 4.14.a and 4.14.b. Cu (I) O and two different cross-linkers FTIR spectra of antibacterial coated cotton fabric the characteristic absorption band indicating the presence of the C = O groups in the ester groups has changed in the range of 1732-1750 cm-1. In addition, the shear characteristic band of -CH- groups is in the range of 1374-1383 cm-1 ,the strain range for C-O groups is 1083-1088 cm-1, the strain range for C-O groups is 1083- 1088 cm-1, the ekran-resmi-2016-12-09-12-31-17tensile vibrations of the -OH groups of the cotton fiber structure give wide and severe bands at 3325 cm-1. Glicidmethacrylate cross-linker with antibacterial coating path when the FTIR spectrum of the coated cotton fabric is examined; aliphatic esters in the structure of glycidmethacrylate carbonyl groups in the isocyanate structure at 1740 cm-1 appears to give a sharper peak. This gives us the antibacterial Cu (I) O chemical shows better binding of cotton fiber together with the coating path.

ekran-resmi-2016-12-09-12-32-19Pre-treatment followed by micro Cu (II) O and two different crosslinkers FTIR spectra of the antibacterial coated cotton fabric are shown in Figures 4.15.a and 4.15.b. O-H and C-H stretching in the spectrum (3333, 2910 and 2161 cm-1) O-H and C-H bending (1645, 1428 and 1315 cm- 1), C-C and C-O stretching (1160, 1107 and 1030 cm-1) The change in the transmittance band at 1645 cm -1 is due to the deformation vibration of the hydroxyl groups. After the antibacterial coating process, new bands emerged which would be a sign of modification. Particularly after coating with glidimethacrylate crosslinker the shear characteristic band for the -CH- groups is 1374-1383 cm-1, the strain range for CO groups is in the range of 1083-1088 cm-1 , while the tensile vibration bands of –CH– groups show more in the range of 2940-2949 cm-1, the stress vibration bands of CH- groups show more in the range of 2940-2949 cm-1. This holds the antibacterial Cu (II) O chemical of the glycidylmethacrylate cross-linker, indicating that the coating material is better maintained to the fiber.

4.Results
ekran-resmi-2016-12-09-12-33-07
Antibacterial treated textile materials are mainly medical, aesthetic and hygienic applications are spreading rapidly in various industrial fields. In this study, coating method was used to impart antibacterial activity to cotton fabrics as material and the effects of the processes are examined step by step. In the FTIR spectra after coating, new bands emerged that would indicate a modification due to coating processes. Carbonyl groups are formed on the surface of the cotton fabric after coating and copper oxide particles in the microparticle size are cross-linked to these groups. It has been observed that the breaking strength of the fabric samples increases after the coating. The binders used in the coating form a lm layer on the surface of the yarn, therefore it sticks all layers of yarn together. In case of polysiloxane based polyurethane; forming a lm layer on the outer side of the yarn, penetrates into the ekran-resmi-2016-12-09-12-34-36bers, as it allows the bers to stick together, causing an increase in the breaking strength. As a result, the copper oxide particles used in coating path depending on the glycidyl methacrylate cross-linker structure are further increases in the breaking strengths in the weft and warp direction of the fabric. In other words; chemical substances containing the isocyanate group of the coating lm, in the reactions with water, emit CO2 gas, the pressure created by the resulting CO2 gas causes the foam to form in the polymer. This causes a decrease in cross-linking in the coating and reduces the breaking strength of the coating. The H atom after coating, substituted with other atoms or groups, it forms as a C=0 functional groups. At the same time, due to the groups formed on the surface and containing oxygen, oxihijyen dation occurs in fabrics. This has been quite effective on fabric strengths. According to ISO 13937-1 test method, in the tear test on the Elmendorf device it was observed that the rupture of coated fabrics more easily than the untreated fabrics.

Reference:
1.Kornphimol Kulthang, Sujitra Srisung, Kanittha Boonpavanitchakul, Wiyong Kangwansupamonkon and Rawiwan Maniratanachote, Determination of Silver Nanoparticle Release from Antibacterial Fabrics into Articial Sweat. Particale and Fibre Toxicology 7:8, (2010).
2.Catalino Marambio-Jones,Eric M.V.Hoek, “A review of the antibacterial effects of silver nanomaterials and potential implications for human helath and the environment”,Journal of Nanoparticle Research, June 2010, Vol.12,Issue 5,pp 1531-1551.
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Investigation of Tensile Properties of Nonwoven Fabrics Produced from Recycled Staple Polyester and Core/Sheath Low Melting Staple Polyester Fibres by Using Carding, Needle Punching, Calendaring and Pressing Machines

Abstract

In this study, tensile properties of nonwoven fabrics produced from recycled staple polyester fibres and core/sheath low melting staple polyester fibres at 1%, 5%, 10%, 20% and 50% blending ratios by using carding, needle punching, calendaring and pressing machines were investigated. The recycled staple polyester fibres and core/sheath low melting staple polyester fibres were used as raw materials. The core/sheath low melting staple polyester fibres were blended with recycled staple polyester fibres at ratios 1%, 5%, 10%, 20% and 50%.

This mixing and web forming operations were carried out at laboratory type carding machine. These webs were bonded mechanically at needle punching machine. These needle punched fabrics were calendared and pressed at 120°C.

The weight per unit area, thickness and tensile properties of the needle punched, thermal bonded and pressed nonwoven fabrics were tested according to ISO and ASTM standards.

The results exhibit that the nonwoven fabric tenacity (cN/tex), tensile strength (MPa), specific strength (MPa/g/cm3) and other specific strength (N.m2/g) increase with the increase of core/sheath low melting polyester staple fibres ratio. It was found that nonwoven fabric thickness and elongation values decrease with increase of core/sheath low melting staple polyester fibres ratio.

Key Words: nonwoven fabric, needle punching, recycled polyester fibre, low melting fibre, calendaring technology, thermal bonding.

I. Introductıon

Nonwoven fibrous webs are mainly bonded by means of mechanical, thermally and chemical techniques depending upon the end product properties and cost. In mechanical bonding process, fibrous sheet or web is bonded together through the application of liquid or air jets, punching felting needles and by stitching with yarn. In chemical bonding, different types of chemicals or binders such as latex, synthetic rubber, acrylics, vinyl esters, styrene and different natural resins are sprayed to the nonwoven web. Other chemical bonding methods applied to nonwoven fabrics are coating, saturation, foam application and print bonding. Thermal bonding requires thermoplastic component to be present in the form of fibre, powder or as a sheath as part of a bi-component fibre. The heat is applied until the thermoplastic component becomes melts in an oven or with calendar cylinders. The thermal bonding process is more economic and environmental friendly. [1]

The rising cost of energy and greater awareness of the environmental impact of latex bonding led to a change in direction. As a result of this, the usage of thermal bonding instead of chemical bonding has increased. The high production rates possible with thermal bonding and the significant energy savings as compared to chemical bonding, due to the absence of significant water evaporation during bonding, makes the process economically attractive. In this method, bi-component and low melt fibres as a raw material are mostly used. [2]

In thermal bonding method, core/sheath bi-component and low melt core/sheath staple fibres are used for bonding fibrous web or for increasing breaking strength of nonwoven fabrics. Such fibres have a core/sheath structure with outer layer having a lower melting temperature that that of the core part. These kinds of fibres are blended and mixed with other staple at specific blending ratios. Bi-component and low melt core/sheath staple fibres have specific core/sheath ratio. In this study, low melt polyester staple fibres with 50/50% core/sheath by weight were used.

Bi-component fibres have been commercially available for years; one of the earliest was a side-by-side fibre called Cantrece developed by DuPont in the mid-1960s followed by Monsanto’s Monvel, which was a self-crimping bi-component fibre used by the hosiery industry during the 1970s. [2]

In Hayes (1992) patent, a melt-bondable bi-component fibre is described which is to be used in nonwoven. First component is a polymer with the capability to form a fibre while the second is a polymer with melting point at least 30°C below that of the first component and with the ability to adhere to the first polymer. Further Hayes recommends polyester as the polymer in the second component as polyester gives better adhesion than other polymeric materials. [3], [4]

Bi-component and core/sheath low melt fibres are made from two components distributed over the entire length of the fibre. They may either belong to the same type of polymer or be totally different polymer types. PET/low melt PET is the low melt polyester fibre consisting of same type of polymer. Polyethylene/polypropylene (PE/PP) is the bi-component fibre consisting of different polymer types. By co-extruding two polymers into one single fibre, the different properties of both polymers are combined. Bi-component fibres are classified according to the distribution of each component within cross-sectional area. Typical cross-section configurations include side-by-side, eccentric, core-sheath, islands-in-the-sea and segmented-pie. [5]

Core/sheath bi-component fibre and core/sheath low melt fibre are the most widely used and the most well-known binder fibre. The sheath part of bi-component fibre or low melt fibre is made from polymers with a low melting. The core part of bi-component fibre or low melt fibre is made from polymers with high melting point. When the fibre is heated, the sheath part of the fibre melts.

The eccentric configuration is used for providing self-crimping properties. The core part of eccentric core/sheath bi-component fibres is out of centre. When then fibre is heated, the fibre curl due to the different shrinking ratios of both polymers. Thus, it is possible to give volume to fibre.

In the side-by-side bi-component fibre, both polymers occupy an equal part of the fibre surface. The fibre may develop more crimp than the eccentric core/sheath configuration.

Segmented pie bi-component fibres are known splittable fibre. Splittables are fibres in which the two polymers share only one common interface and both polymer phases are also exposed.

Island/sea bi-component fibre consists of sea part and islands part. When the sea part of the fibre is dissolved, fabric is produced on the basis of very fine microfibers. These fibres (typically 37 islands) are used in the production of suede fabrics. The process is not often environmentally friendly because of the solvents employed in the removal of the sea part. Evolon® is the commercially spunbonded fabric made from island-in-the-sea polyester/nylon fibres with 16 segmented pie. The polyester and nylon fibres are split and bonded mechanically water-jet (hydroentanglement) technology with high pressure [7], [5]

In this study, the tensile properties of the nonwoven fabrics produced from recycled staple PET polyester fibres and core/sheath (50/50) low melt staple polyester fibres at specific blending ratios by using the carding, needle punching, calendaring and pressing machines were studied. In this regard, the effect of core/sheath low melt staple polyester fibre ratios on nonwoven fabric tenacity was investigated.

Iı. Experimental Study

II.1. Material and Method

In this study, 3 denier 51 mm recycled staple polyester fibres with white colour were used as carrier fibre. 4 denier 51mm core/sheath staple polyester low melting fibres with black colour supplied from Toray Company were used as binder fibre. These fibres are mainly used in the production of needle punched fabric and acquisition distribution layer/fabric (ADL). Table1 and Table2 present main properties of used recycled staple polyester fibre and core/sheath low melting staple polyester fibre.

Low melting polyester staple fibre is used as binder (a bonding agent) to combine staple fibres using heat in the manufacturing process of nonwoven fabric, and it is mainly used in nonwoven fabric used for acoustic insulation material for automotive, acquisition distribution layer (ADL) and cushions for mattress and other furniture. Manufacturers have been switching from the conventional chemical adhesive method using chemical agents, for manufacturing nonwoven fabric, to a thermo-bonding method given the rising awareness for environment-friendliness. Low melting polyester staple fibre is the eco-friendly material used in thermo-bonding and its global market is expanding at a rate of 8% a year. For this reason, the competition in the industry has been intensifying, as manufacturers with top market shares in the LM polyester staple fibre market invests in manufacturing facilities and other companies are newly entering into the market. [8]

The typical cross-section of core/sheath low melt staple polyester fibre is shown in Figure3.  The low melt staple polyester fibre was of core/sheath (50/50) type with a round cross section; core of conventional polyester and a sheath of co-polyester with a melting point of 110°C.

Core/sheath bi-component and low melt polyester staple fibres are utilized for sound absorption in vehicles. There is a rise in automobile applications in emerging economies, as market expands on expansion of requirements for lighter vehicles and for sound absorption. These fibres are used for mattresses, bed padding, sofa cushion materials and in quilt. The fibres are preferred high precision filter for purification. In construction applications, the fibres are used for sound, shock absorption, insulation and for preventing cracks. Other applications of these fibres are cloth interlining, inner soles and agricultural materials.

II.2. Production Method

In the experimental study, the nonwoven fabrics were manufactured at four steps. In the first step, the webs were produced from recycled staple polyester and low melting staple polyester fibres prepared at different blending ratios at carding machine. In the second stage, these webs were mechanically bonded at needle punching machine. In the third stage, needle punched nonwoven fabrics were thermally bonded at calendaring machine. In the fourth stage, thermally and mechanically bonded nonwoven fabrics were pressed. The tensile properties of nonwoven fabrics depend on needle punching machine parameters such as depth of needle penetration, needle type and needling density per cm2.

Wool type carding machine is the most used machine for web forming from staple natural and synthetic fibres. Carding is defined that a process for making fibrous webs in which the fibres are aligned parallel or to each other or random orientated. The fibrous web is produced at the end of the carding machine. In the study, laboratory type sample carding machine was used for making webs as you can see in following figure. [9], [10]

337A laboratory wool type sample carding machine of Mesdan S.P.A. was used for web forming operations. The machine has 4-5kg/h production capacity and 10-15m/min web delivery speed.

The machine is designed to assess the carding performance and quality of staple fibres as well as to produce webs. In addition to this, this machine is suitable for preparing homogeneous coloured fibre samples.

The equipment is composed by a wide conveyor, a pair of feed rollers, three pairs of workers and strippers, main carding cylinder, doffing roller, fancy roller and clearer together with a web collecting drum.

In the first step, the recycled staple polyester fibres and low melting staple polyester fibres were weighted according to blending ratio.

These fibres were mixture by hand before carding machine.

These fibre mixtures were run through the carding machine two times, first time for opening the fibres and second time for blending. Webs were produced at the end of the carding machine.

Needle punching technology was used to consolidate of fibrous structures (web).

Needle punching is a process of bonding nonwoven fibrous web structures by mechanically interlocking the fibres through the web. Barbed needles mounted on a board, punch fibres into the web and then withdraw leaving the fibres entangled.

By varying the stroke per minute, the advance rate of the web, and the degree of penetration of the needles, a wide range of fabric densities can be achieved. [9], [10]

The bonding of staple fibres in these webs was carried out at needle punching machine by using felting needles. 74.3punch needling density per cm2 and 12.5mm needle penetration depth at pre-needling machine was applied to webs. The pre-needled nonwoven fabrics were bonded in the second and third needling machines at 123punch/cm2 and 125punch/cm2 needling density and 10mm and 8mm needle penetration depth respectively.

Needle punched fabrics were thermally bonded by passing through the smooth calendar cylinders at 120°C. The needle punched and thermally bonded nonwoven fabrics were pressed at machine for better melting of low melting fibre at 120°C for 120second under 120bar pressure.

Thermally bonding is the process of using heat to bond or stabilize a web structure that consists of a thermoplastic fibre. Thermally bonding is known melt bonding or heat bonding. [12] The basic concept of thermally bonding was introduced by Reed in 1942. [2] The process is relatively simple. There are mostly used two kind of thermally bonding methods. One of them is bonding with calendar cylinders. Another method is through-air ovens. Hot calendaring and hot oven are the most frequently used methods for thermally bonding of nonwoven webs and fabrics. [9], [10]

II.3. Testing Methods

The weight, thickness and tensile properties of the produced mechanically needle punched, thermally calendar cylinders bonded and pressed nonwoven fabrics were done according to ISO ad ASTM standards.

II.3.1. Thickness Test

The thickness of fabrics is determined as the distance between the upper and the lower surfaces of the material, measured under a specified pressure. Thicknesses of nonwoven fabrics were measured at R&B Cloth Thickness Tester produced from James H.Heal&Co.Ltd Halifax England. Thickness test was done according to TS EN ISO 9073-2 standard. Thickness of nonwoven fabric was measured under 1g per cm2 and 5g per cm2 pressure respectively at the R&B Cloth Thickness Tester. Obtained results were averaged. It was seen that thickness of nonwoven fabric decreased with increase of low melting fibre ratio. [13], [14]

II.3.2. Tensile Strength Test

Instron 4411 tensile testing machine was used to measure the tensile and breaking strength of nonwoven test samples as specified in ASTM D5035-06 Standard Test Method for Breaking Force and Elongation of Textile Fabrics according to strip method. The nonwoven fabric tenacity (cN/tex) was determined according to following equation. Six samples were taken only machine direction (MD). The samples were cut and prepared at 50x175mm dimensions. Test length (the distance between the fixtures) was adjusted to 75mm. Test speed was 300mm per minute. A mean of six test results has been calculated in only machine direction (MD). All samples were conditioned at 65%±2°% relative humidity and temperature of 20±2°C prior to each test at physical testing laboratory of Marmara University Technology Faculty Textile Engineering Department.

The fabric density (g/cm3) was calculated by dividing fabric weight per area (g/m2) by fabric thickness (mm) [15] [16]

The nonwoven fabric tenacity (cN/tex) and specific strength was determined according to following equations.

Specific strength (MPa/g/cm3) is generally used for removing effects of the fabric thickness and fabric weight per unit area on tenacity and strength of nonwoven fabrics. Specific strength (MPa) can be calculated by dividing tensile strength (MPa) by fabric density (g/cm3).

Other specific strength (N/m2/g) was found by considering the breaking strength (N) and fabric areal weight (g/m2) of needle punched, thermally calendar cylinders bonded and pressed nonwoven fabrics. Specific strength was calculated by dividing breaking strength (N) by fabric areal weight (g/m2). Thus, it is possible to compare similar nonwoven fabrics with different basis weight. [17]

Results

Table3 presents the mean of measuring areal weight, thickness and breaking strength values. It was clearly seen that thickness of nonwoven fabric decreases with increase of low melting fibre ratio in the mechanically needle punched, thermally calendared and pressed nonwoven fabric.

The results clearly showed that low melt fibre percentage had a significant impact on nonwoven fabric thickness and thickness of nonwoven fabric decreases with increase of core/sheath low melt staple polyester fibre ratio.

The breaking strength test results of needle punched, thermally calendar cylinders bonded and pressed nonwoven fabrics show that increase of core/sheath low melting staple polyester fibre ratios from 1%, %5, 10%, 20% and to 50% increase the fabric tenacity by 4.57cN/tex, 5,25cN/tex, 5.28cN/tex, 5,46cN/tex and 5.58cN/tex respectively.  On the other hand, increase of core/sheath low melting staple polyester fibre ratios from 1%, %5, 10%, 20% and to 50% decrease elongation (%) values by 71,52%, 47,97%, 40,14%, 33,11% and 28,91% respectively.

Figure8 shows effect of core/sheath low melting staple polyester fibre ratio on nonwoven fabric tenacity (cN/tex). The results show that fabric tenacity (cN/tex) increases slowly with increase of core/sheath low melting staple polyester fibre ratio. This can be explained by the fact that the core/sheath low melting staple polyester fibres have high bonding force.

Figure9 indicates effect of core/sheath low melting staple polyester fibre ratio on breaking elongation (%). Elongation results show that breaking elongation (%) decreases considerably with increase of core/sheath low melting polyester staple fibre ratio.

Figure10 shows effect of low melting staple polyester fibre ratio on tensile strength (MPa). Results show that tensile strength (MPa) increases considerably with increase of core/sheath low melting staple polyester fibre ratio.

Figure11 shows effect of low melting polyester staple fibre ratio on specific strength (MPa/g/cm3).  Results show that specific strength (MPa/g/cm3) increases with increase of core/sheath low melting staple polyester fibre ratio.

Figure12 shows effect of core/sheath low melting polyester staple fibres ratio on specific strength (N.m2/g). Results show that specific strength ((N/m2/g) increases with increase of core/sheath low melting staple polyester fibre ratio.

Conclusion

This experimental study clearly shows the effect of core/sheath low melting polyester staple fibre on tensile strength test results of mechanically needle punched, thermally calendar cylinders bonded and pressed nonwoven fabrics. The recycled staple polyester fibres (r-PES) were blended with core/sheath low melting staple polyester fibre (bi-co PES). The core/sheath low melting staple polyester fibres were used at %1, 5%, 10%, 20% and 50% ratios. The nonwoven fabric production was carried out at carding, needle punching, calendaring and press machines. The following results have been obtained.

•Thickness of nonwoven fabric considerably decreases with increase of core/sheath low melting polyester staple fibre ratio.

•Fabric tenacity (cN/tex) increases with increase of core/sheath low melting polyester staple fibre ratio.

•Elongation values (%) decrease considerably with increase of core/sheath low melting polyester staple fibre ratio.

•Tensile strength (MPa), specific strength (MPa/g(cm3) and specific strength (N.m2/g) increase with increase of core/sheath low melting polyester staple fibre ratio.

Acknowledgement

I would like to thank to Hassan Group for support.

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