AN EXPERIMENTAL STUDY ON AIR PERMEABILITY AND BURSTING STRENGTH IN DIGITAL PRINTED FABRIC

AN EXPERIMENTAL STUDY ON AIR PERMEABILITY AND BURSTING

STRENGTH IN DIGITAL PRINTED FABRIC

Şehpal ÖZDEMİR45 Füsun DOBA KADEM46

ABSTRACT

Garments greatly affect the heat exchange between the human body and the environment. Therefore, consumers prefer thermally balanced and effective moisture controlled products in the selection of clothing. Air permeability is also important in explaining the comfort performance of the product in textile industry.

On the other hand, digital printing machines have become the center of attention of consumers as a print type on which the desired pattern can be printed on the desired fabric and more ecological, faster and economical. However different printing processes can change the comfort characteristics of the garments.

In this study, single jersey knitted fabrics which produced 100% tencel and 100% cotton raw materials were colored with digital printing, after that, air permeability and bursting strength tests applied to both samples before and after printing. When the test results are evaluated; it was concluded that the digital printing process increases the air permeability and decreases bursting strength of the samples after printing.

Key words:

DİJİTAL BASKILI KUMAŞLARDA

HAVA GEÇİRGENLİĞİ VE PATLAMA MUKAVEMETİ ÜZERİNE

DENEYSEL BİR ÇALIŞMA

Giysiler, insan vücudu ve çevre arasındaki ısı değişimlerini büyük ölçüde etkilemektedir. Bundan dolayı günümüzde tüketiciler giysi seçiminde ısıl olarak dengeli ve etkin nem

kontrolü sağlayan ürünleri tercih etme eğilimindedirler. Kumaşların hava geçirgenliği tekstil endüstrisinde ürünün konfor performansını açıklamada önem arz eden bir kavramdır. Öte yandan dijital baskı makineleri, gelişen teknoloji ile birlikte artık istenilen kumaş üzerine istenilen desenin basılabildiği, daha ekolojik, daha hızlı ve ekonomik bir baskı türü olarak tüketicilerin ilgi merkezi haline gelmiştir. Fakat farklı baskı süreçleri giysilerin konfor özelliklerini değiştirebilmektedir.

Bu çalışmada 100% tencel ve 100% pamuk hammaddelerinden üretilmiş süprem örme kumaşlara dijital baskı ile renklendirme işlemi yapılmış, baskı öncesi ve baskı sonrası bu kumaşların patlama mukavemeti ve hava geçirgenliği deneysel olarak tespit edilmiştir. Yapılan test sonuçları değerlendirildiğinde; uygulanan dijital baskı işleminin baskı sonrası numunelerin hava geçirgenliklerini artırdığı, patlama mukavemetini azalttığı sonucu elde edilmiştir.

Anahtar Kelimeler:

1. Introduction

In the ancient times, the thready materials (like fibers) that people found around are the origin of textiles. They were aimed to cover and protect people from natural conditions. Later on, people colored these products with dyes obtained from nature and with their instinct to express themselves; they shaped their feelings and thoughts on these fabrics. These regional dyeing made to obtain colored patterns on textile products are called printing [1].

Nowadays, the textile and garment industry is one of the sectors in which developed and developing countries continue to exist and where global competition is most intense. So the companies have to improve themselves in terms of cost, terminology and quality, environmental and sustainable production facilities, design and innovation.

Fabrics are classified according to their production method. This is shown below in Figure 1. Knitted Fabrics Woven Fabrics Non-wovens

Knitting is the process of intermeshing of loops formed by a single source of yarn. If compared, it can be said that knitted fabrics are more flexible and formable. Technically, knitting is divided into two main groups (Figure 2).

In Weft Knitting, the single yarn makes transverse loops. These loops form a surface that results from the connection with the upper and lower loops of the loops. Some of the products obtained by the weft knitting method are; sweaters, vests, jackets, skirts, dresses such as outer garments, undershirts, panties, such as underwear, T-shirts, sweatpants, sweet-shirt, such as combed products, socks, some medical and technical fabrics.

In warp knitting, at least one yarn is fed to each needle. The surface is formed by connecting each stitch with the stitch bars next to the stitch bars which are formed separately. Some of the products obtained by warp knitting method are; tulle curtain, lace, swimwear and upholstery fabrics, towel and carpets, medical materials such as bandages and artificial veins, shoe faces, filters, sacks, technical fabrics such as greenhouse cover [3].

Figure 2. Shape of Knits [4]

For the first half of 2018, three main product groups of export increased by between 6,3% and 9,7%. Export of knitted products, which is the most exported product group, increased by 6,3% in January-June 2018 compared to the same period of 2017, reaching 4,5 billion dollars. These values are seen in Table 1.

Table 1.Export Values of Knitted Products [5].

Nowadays, fashion trends affect the woven and knitted apparel products. In this context, digital printed products have an important place in the sector in recent years.

Digital printing is a coloring method for the textile surface by using a computer-aided design. Digital textile printing is suitable for multi-coloring and a proper alternative to traditional printing methods.

The advantages of digital printing can be listed as follows;

*Unit printing costs can be an alternative to conventional printing. *Print quality is high.

*In conventional methods, pre-print process takes a lot of time and is costly. *Low meters of fabric can be printed.

*It is environmentally friendly. It saves waste water and energy [6].

Digital printing applications have different products as textile surface (t-shirt, home textiles, coat etc.) and hard surface (mouse pad, mug, glass, floor covering etc.) applications. In Figure 3, digital printing machine is given which is commonly used in applications and used in this study.

Figure 3. Digital Transfer Printing Machine [7]

When the literature is examined, it is seen that there are many academic studies about knitting. However, studies on physical properties of printed products have not been found. Examples of some experimental research are given below.

In their study, Mavruz and Oğulata found a linear relationship between air permeability values and yarn count, fabric thickness, stitch frequency and loop length. Supreme structures generally have the highest air permeability values, followed by rib and interlock structures [8].

In Ütebay's study, ink-jet printing on reactive dye-based inks and cotton fabrics investigated the process conditions in which the best results could be obtained in terms of color yield, contour clarity and fastness properties [9].

Onar Çatal et. al. aimed to investigate the effect of rheological properties of pre-treatment thickeners on print quality and color yield. In this study, it was revealed that the rheological properties of the pre-treatment pastes in ink-jet printing have no significant effect on color yield and print quality [10].

The aim of Karakaş is determination of physical and some thermal properties belongs to cotton, polyester and polyamide warp knitting fabrics and evaluation of these results. For this aim, 100% cotton, 100% polyester and 100% polyamid warp knitting fabrics with different constructions were produced. Some selected physical and performance properties of these fabrics were determined experimentaly according to relevant standarts. These properties were listed as weight, fabric thickness, loop frequency, loop yarn length, weave repeat, drying properties of the fabrics and water vapor resistance. Obtained results were interpreted with graphs [11].

Gülşen Bakıcı et. al. investigated the effects of selected construction properties of single jersey fabrics on thickness, air permeability and pilling properties in their study. Ne 12/1, Ne 16/1 and Ne 20/1 yarns produced from the same cotton blend were used to compare fabric performance characteristics. It is seen that yarn number and loop density have an effect on thickness and air permeability properties. The increase in the stitch density of the fabrics produced with the same number resulted in a decrease in the thickness and air permeability values [12].

In Hajipour and Nateri’s research, the effect of weft density on the inkjet printing of polyester was investigated. Lines with different widths were printed in the warp and weft directions, and the print quality was evaluated as the line width. The obtained result showed that the weft density affected the line width and the print quality decreased with an increased weft density. The width of the lines printed in the weft direction is more than the width of lines printed in the warp direction. The investigation of the relation between the print quality and the vertical wicking shows a very poor relation between the two [13].

2. Material and Method

In this study, single jersey knitted fabrics which produced from 100% tencel and 100% cotton raw materials were colored with digital printing, after that, air permeability and bursting strength tests applied to both samples before and after printing. Fabrics remain under the influence of not only in the weft and warp direction forces, but also multi-directional forces

Bursting strength is extremely important especially for knitted fabrics. The fabric bursting strength was tested according to the BS EN 13938-2 testing method [14].

Figure 4. Bursting strength tester [15]

The air permeability test is determines the warming, wind protection and breathability characteristics of the knitted fabrics. Thus, with the help of air permeability results, the effect of digital printing on some comfort properties can be determined [16]. This test was carried out according to TS 391 EN ISO 9237 standard [17].

Figure 5. Air permeability tester [18]

Yarn quality properties of samples are given in table 2. Table 2.Yarn properties

Material Ne U% CVm% Thick -40% Thin +50% Nep +200% H Rkm (kgf*Nm) B-force (gF) Elongation % Cotton 23,79 8,94 11,27 9,50 5,50 9,50 7,94 15,43 383,1 6,90 Tencel 23,62 8,36 10,57 10 4,50 14,50 6,64 28,90 722,70 11,37

Knitting machine properties that samples were produced are shown in Table 3.

Machine/Model Pus (Diameter)(mm) Fayn Needle(Total Number)

Mayer & Cie 762 18 1680

After knitting, specified simple pattern was applied by digital printing method to fabrics. Fabrics were tested before and after digital printing because of measuring the effect of digital printing on air permeability and bursting strength.

3. Results and Discussion

The following table shows the frequency properties of fabrics based on TSE - TS EN 14971 Standard [19].

Table 4.Fabric’s Frequency Properties

Sample Wale Count per cm Mean St. Dev.

Cotton 9.25 9.84 9.25 9.06 9.45 9.37 0.27

Tencel 8.27 8.86 8.46 8.27 8.27 8.43 0.23

Sample Course Count per cm Mean St. Dev.

Cotton 11.02 10.63 11.02 11.02 11.02 10.94 0.16 Tencel 10.63 11.42 11.02 10.24 10.43 10.75 0.42

Table 5. Air Permeability Results (m3_/s)

Before Digital Printing After Digital Printing Cotton Tencel Cotton Tencel

1 2443 3340 3711 5416 2 2443 3340 2537 4888 3 2560 3455 2505 5138 4 2569 3455 2444 5416 5 2443 3578 2505 4888 6 2443 3340 2947 5010 7 2443 3340 2603 5010 8 2560 3455 2991 5010 9 2569 3455 2863 5274 10 2443 3578 3181 5274 Mean 2491.60 3433.60 2828.62 5132.39 St. Dev. 59.5906 88.64446 379.2461 191.2227

Considering all construction characteristics, it was observed that air permeability values increased for both finished (printed) fabrics after printing applications. When the finished, semi-finished and raw fabrics were compared, Eryürük (2004), found the air permeability values of the finished fabrics higher too. The air permeability of cotton fabric increased by 13%, tencel fabric increased by 49%.

Before Digital Printing After Digital Printing

Cotton Tencel Cotton Tencel

1 584.9 699.3 446.3 614.8 2 511.9 725.3 467 605.3 3 582.7 722.5 412.7 551.3 4 613.6 716.1 467.3 553.4 5 560.7 716.7 433.2 594.3 Mean 570.76 715.98 445.3 583.82 St. Dev. 33.89239 9.034689 20.80894 26.51003

The Bursting strength of cotton fabric decreased by 21%, tencel fabric decreased by 18%. Bursting strength results were found to be proportional to the strength differences of cotton and tencel yarns. Tencel raw material with high yarn strength has high Bursting strength. These findings are consistent with the evaluations in the literature. The same situation was maintained after printing.

4. Conclusion

In this study, single jersey knitted fabrics which produced from 100% tencel and 100% cotton raw materials were colored with digital printing, after that, air permeability and bursting strength tests applied to both samples before and after printing. When the test results are evaluated; it was concluded that the digital printing process increases the air permeability and decreases bursting strength of the samples after printing.

Air permeability and explosion strength are also influenced by many factors such as fiber structure, yarn count, porosity, fabric construction and applied finishing processes. In the studies conducted in the literature, the results show that the air permeability of the finished fabrics is better than the air permeability of the semi-finished fabrics from the same raw materials and constructions. The results of this study also support this situation.

The bursting strength of printed fabrics which have different raw materials and almost same identical features showed a tendency to decrease after printing. Based on the fact that the yarn strength affects the bursting strength, the bursting strength of the knitted fabric made of tencel yarn is higher than cotton knitted fabric as expected. It was found that the printing process had a decreasing effect on both raw materials.

5. References

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2. ( https://tekstilsayfasi.blogspot.com/2015/10/dokuma-ve-orme-arasindaki-farkliliklar.html) Accessed: November 2018

4. Marmaralı, A., Kretzschmar, S.D., Özdil, N., Oğlakcıoğlu, N.G., 2006. Giysilerde Isıl Konforu Etkileyen Parametreler. Tekstil Ve Konfeksiyon, 4: 241-246

5. https://www.ihkib.org.tr/fp-icerik/ia/d/2018/08/07/performance-report-of-turkish-apparel-export-january-june-2018-201808070304250530-ED838.pdf, Accessed: November 2018 6. http://Www.Tekstilteknik.Com.Tr/Dijital-Baski-Sektorunde-Degisim-Cok-Mu-Yakin/ Accessed: November 2018 7.

http://turalmakina.com.tr/tr-34-TC-610-METRAJ-TRANSFER-BASKI-MAKINASI.html Accessed: November 2018

8. Mavruz S.,. Oğulata R.T., 2009. Pamuklu Örme Kumaşlarda Hava Geçirgenliğinin İncelenmesi Ve İstatistiksel Olarak Tahminlenmesi, Tekstil Ve Konfeksiyon 1/2009 29-38.

9. Ütebay B. 2010. Pamuklu Kumaşlara Uygulanan Ink-Jet Baskı İşleminde Renk Verimine Etki Eden Faktörlerin İncelenmesi, Ege Üniversitesi Fen Bilimleri Enstitüsü Tekstil Mühendisliği Anabilim Dalı Yüksek Lisans Tezi, İzmir.

10. Onar Çatal D., Özgüney A.T.,. Akçakoca Kumbasar E.P., 2012. The Influence Of Rheological Properties Of The Pretreatment Thickeners On Ink-Jet Printing Quality, Tekstil Ve Konfeksiyon 4/2012 309-316.

11. Karakaş, O, 2016. Seçilmiş Çözgülü Örme Kumaşlarda Bazı Isıl Konfor Özelliklerinin Araştırılması. Ç.Ü.Fen Bilimleri Enstitüsü Tekstil Mühendisliği Anabilim Dalı Yüksek Lisans Tezi. Adana. 93 s.

12. Ala D.M., Gülşen Bakıcı G., Abdulvahitoğlu A. 2017. Süprem Örme Kumaşlarda Kalınlık, Hava Geçirgenliği ve Boncuklanma Özelliklerinin İncelenmesi Çukurova Üniversitesi Mühendislik Mimarlık Fakültesi Dergisi, 32(3), ss. 103-109.

13. Hajipour A., Shams-Nateri A.,2017. The Effect of Fabric Density On The Quality Of Digital Printing On Polyester Fibers And Polymers, Vol.18, No.12, 2462-2468.

14. TS EN ISO 13938-2 Textiles- Bursting properties of fabrics- Part 1: Hydraulic method for determination of bursting strength and bursting distension.

15.

http://aygenteks.com/cihazlar/tekstil/kumas-fiziksel-testleri/truburst-patlatma-mukavemeti/ Accessed: November 2018.

16. Selli F., 2013. Ticari Süprem Ve Ribana Örme Kumaşlarda Hava Geçirgenliği ve Nem Yönetiminin Araştırılması, Pamukkale Üniversitesi Fen Bilimleri Enstitüsü Tekstil Mühendisliği Anabilim Dalı Yüksek Lisans Tezi, Denizli.

18. http://www.prowhite.eu/hava_gecirgenlik_test_cihazi.html) Accessed: November 2018. 19. TSE - TS EN 14971 Textiles - Knitted fabrics - Determination of number of stitches per

unit length and unit area.

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