Pet karışımlı viskon örme kumaşlarda parça boyama sonrası ortaya çıkan boncuklanma probleminin araştırılması ve iyileştirilmesi
Research and improvement on pilling problems observed in garment dyed knitted fabrics with polyester and viscose blend yarns
Yazar: ERKAN BEKİROĞLU
Danışman: PROF. DR. GÜLAY ÖZCAN
İstanbul Teknik Üniversitesi / Fen Bilimleri Enstitüsü / Tekstil Mühendisliği Ana Bilim Dalı / Tekstil Mühendisliği Bilim Dalı
Derece: Yüksek Lisans, 2020
Konu: Tekstil ve Tekstil Mühendisliği = Textile and Textile Engineering

Özet:
Parça boyama işlemi sonrası giysilerin görünümü (özellikle dikişlerdeki eskitme efekti) pazarda ciddi talep gören bir moda eğilimi haline gelmiştir. Bununla birlikte parça boyama işleminin modadaki anlık değişimlere hızlı cevap verebilmesi parça boyamaya olan ilginin daha da artmasına sebep olmuştur.
Parça boyama işleminin en önemli ise boncuklanma problemidir. Özellikle sentetik lif karışımlı kumaşlarda boncuk oluşum hızının, koparak dökülme hızından daha yüksek olması, bu problemin daha fazla yaşanmasına sebep olmaktadır. Parça boyamada, genel olarak giysi ya da parçaların işleme girmeden önce hazırlıkları yapılmaktadır. Ham haldeki kumaştan dikilen ürünlerin parça boyama işlemi yapılacaksa bu durumda mutlaka iyi bir ön terbiye işleminden geçirilmesi gerekmektedir. 
Viskon /PET karışımlı ipliklerden elde edilen örme kumaşların parça boyama makinasında reaktif boyarmaddelerle boyanmasıyla tatmin edici melanj efektlerin alınabilmesi, pazar taleplerinin hızla karşılanmasını sağlarken melanj renk gamı ile ilgili yeterli renk çeşitliliği olmaması ve renk başına minimum üretim miktarının yüksek olması gibi sorunlara da önemli bir çözüm getirmiştir.
Polyester (PET) ile viskon lifinin farklı oranlardaki karışımı, kumaşlarda farklı tonlarda melanj görüntüsü almaya imkan vermektedir. Fakat buradaki en büyük kısıt, istenen iplik numarasında ve karışımda ipliğin tedarik edilememesidir. Bu sorunu çözebilmek için pazarda yaygın olarak ring eğirme sistemiyle üretilmiş iplikler kullanılmaktır. Bununlabirlikte pazarda her iplik numarasında ve karışımda ipliği rahatlıkla bulabilme imkanı veren ring ipliklerinin boncuklanma açısından ciddi sıkıntıları söz konusudur.
Özellikle yüksek kopma dayanımına sahip PET lifi karışıma dahil olması ve kullanılan ipliklerin ring eğirme sistemiyle üretilmiş olması, boncuklanma sorununu daha da arttırmaktadır. Tüm bu sorunlar dikkate alınarak tez çalışmasında; Viskon/PET karışımı ring ipliğin, karışım oranı, iplik büküm katsayısı, bu ipliklerle elde edilen örme kumaşların ön terbiye, boyama ve bitim işlemlerinin kumaşların boncuklanma eğilimi üzerine etkisi incelenmiştir.
Bu tez çalışması için Viskon/PET'in 5 farklı karışım oranında kullanıldığı ve αe değerleri 3,00-3,54 arasında değişen toplam 5 farklı tipte ring iplikleri üretilmiştir. 
Üretilen ipliklerle, açık en yuvarlak örme makinasında her biri 10 kg olacak şekilde, % 80/20, 50/50, 33/67 Viskon/PET karışımı 3 tip kumaş ve kontrol amaçlı %100 Viskon ve %100 PET iplikten yapılan örme kumaşlar üretilmiştir.
Farklı karışım oranlarındaki ipliklerden örülen süprem kumaşlara 20 farklı işlem uygulanarak toplamda 100 adet numune üretilmiştir. Kumaşlar, açık en olarak ön terbiye işlemlerinden geçirilmiştir. Ardından 1 er metre boyutlarında kesilerek parça boyama makinasında 3 farklı boya konsantrasyonunda hazırlanan boyama reçeteleriyle boyandıktan sonra biyo-parlatma işlemi ve son olarak 3 farklı reçete ile bitim işlemlerine tabi tutulmuştur.
Tez kapsamında yapılan literatür araştırmaları ve deneysel çalışmalar sonucunda, Viskon/PET karışımlı kumaşlarda PET oranı arttıkça, literatüre paralel olarak termofikse adımının eklenmesi ve maliyet parametresi ile birlikte sürdürülebilirlik açısından bir işlem basamağının ve kimyasal kullanımının azaltılması göz önüne alındığında enzim uygulama basamağının çıkarılmasının boncuklanmayı tatmin edici düzeyde azaltabileceği gözlemlenmiştir. Termofikse işleminin %80/20 Viskon/PET ve %100 Viskon kumaşlarda önemli bir etkisinin olmadığı gözlenmiştir. Bu sebeple karışımda viskon oranının artmasıyla enzim ve gaze işlemlerinin ön terbiye için yeterli olduğu tespit edilmiştir. Yine parça boyama makinasında boncuklanmayı iyileştirmeye yönelik uygulanan bitim işlemlerinin (poliüretan ya da silisik asit karışımı) hem boyanmış üründeki renk değişimini kabul edilebilir sınırlarda etkilediği hem de tuşeyi bozmadan iyi bir boncuklanma performansı sağladığı gözlemlenmiştir.
Tez kapsamında elde edilen veriler ışığında düşük boncuklanma performansı için işlem adımları; kumaşa gaze, yıkama, PET oranı %50 ve üzerinde ise ramözde termofikse, kesim, dikim, parça boyama (%80 doluluk oranı ile), viskon oranı %50 ve üzerinde ise enzimatik işlem, poliüretan veya poliüretan ile silisik asit esaslı  kombinasyon bitim işlemi reçtesini çektirme yöntemiyle ürüne aktarma, santrifüjde sıkma, optimum devirde (18 dev/dak) tamburlu kurutucuda kurutma, ütü ve paket şeklinde sıralanabilir.

Abstract:
Pilling is a surface defect of fabrics caused by the entanglement of short or broken fibers on the fabric surface resulting in small spherical bundles. It is a serious and common problem that occurs in garment dyed fabrics due to the prolonged drying of the fabric.  With this aim, this study focuses on the pilling problem of the products knitted with different blend ratios of polyester/viscose yarn. A total of 5 different types of ring yarns were produced, in which viscose/ polyester (PET) was used in 5 different blend ratios. With the produced yarns, viscose / PET fabrics were produced in 3 different blend ratios, 80/20, 50/50, 33/67, in open width circular knitting machine. In addition, knitted fabrics made of 100% viscose and 100% PET yarn were produced as control samples. A total of 100 samples were produced by applying 20 different processes to single jersey fabrics knitted from yarns with different blending ratios. The pilling results obtained after the experiments involving 20 different finishing processes/combinations were statistically evaluated using the Minitab program.
Worn out the (aged) appearance of garment dyed clothing products, especially the distressed effect on the seams, is a popular look that has been in demand in the fashion industry. In addition, with its ability to provide a rapid response to the instant changes and demands of the fashion industry, garment dyeing has become an even more attractive application in the fast paced world of fashion. Comparing the processing time of garment dyeing and the process of fabric dyeing and then sewing the product, the time of product production by garment dyeing is reduced by 33%. In the fast fashion industry, being able to respond quickly to instant changes in demand, low inventory amount per color, low inventory levels, and easy inventory control are also important advantages. Other reasons why garment dyeing is preferred; the lack of dyed fabric stock remaining after fabric dyeing, the product does not shrink after the final consumer washes, the energy, water and workmanship costs are much lower, the flexibility to produce in much smaller batches and the color tone in different parts of the product arising from the color shade difference between the edges after fabric dyeing. Despite its many advantages, an important disadvantage of the garment dye process is pilling. Especially with the introduction of synthetic fibers that have a higher pill formation rate than the pills' breaking rate, this problem has increased even more. Pilling is an important problem not only for textile and clothing manufacturers but also for end users as it reduces the lifetime of the product.
When the fibers in the yarn migrate to the surface, a hairy surface is formed and these free fibers on the surface knot to form pills. In addition, foreign materials adhere to the pills and get bigger. The pills reaching a certain size due to mechanical effects either break or stay in the place. If the force exerted by an external effect is greater than the holding force of the fiber that holds the pill, it will detach from the surface. Otherwise, it stays on the surface. The direct causes affecting the formation of pilling are frictions during the use of the product and hydrodynamic forces that occur during washing. The indirect reasons are that the fibers migrate to the surface due to the mobility of the fibers during use and washing.
Factors affecting pill formation are fiber type, fiber shape, fiber fineness, fiber tensile strength, fiber length, fiber flexibility, fiber bending ability, yarn twist, yarn spinning technique and fabric structure. In the complexity of the fibers; The cross-sectional shape, fineness and stiffness of the fiber are important. The parameters that are effective in the breaking of the formed pills over time are abrasion resistance, bending ability and flexibility of the fiber. Compared to hydrophilic fibers (viscose, cotton, wool), hydrophobic fibers such as PET tend to attract foreign matter due to their electrostatic properties, also their pill residence time is much more. Twisting is an important factor in terms of individual mobility of the fibers in the yarn and the tightness of the yarn. The problem of pilling always appears in fabrics knitted with low twist yarns. Fabric type, fabric texture or mesh type, fabric density and fabric weight are fabric properties that affect pilling. Due to the larger gaps in knitted fabrics, fibers move more comfortably than woven fabrics. Therefore, pilling is more common in knitted fabrics.  
Within this scope of the study, the pilling property of knitted fabrics with different blend ratios of viscose/PET was investigated. Since there are so many parameters affecting pilling, the yarn and fabric properties used in this study were kept the constant and 20 different processes were applied to single jersey fabrics knitted from yarns with different viscose/PET blend ratios. The pilling values of the fabrics were determined with ICI-Pilling Box and the pilling results were statistically evaluated using the Minitab program. 
In the study, yarns were produced in close twist coefficients (αe). The value of αe: 3,6 is the most commonly used as twist coefficient. In general, if a soft touching is desired in knitted fabrics, the αe value of the thread is between 3.00-3.60 and 3.80-3.90 values for a harder touching. The yarns' αe were kept between 3.00-3.54 both to prevent the product skewness due to the garment dyeing and to be able to get a soft touching. Since the most widely used ring yarns in the yarn production technologies in the literature can easily be found in all kinds of blending ratios and yarn numbers, ring yarns consisting of 5 different fiber blend ratios with αe values between 3,00-3,54 were produced. Fabrics made of 100% viscose (CV) and 100% polyester (PET) yarn were produced as control samples. 
A total of 50 kg single jersey fabric was knitted by a wide-open circular knitting machine using 30 gauge, 28 fein, 96 systems and 2640 needles with the produced yarns.
A total of 100 samples were obtained by applying 20 different processes to single jersey fabrics produced with the yarns consisting of different compositions. The fabrics were subjected to different pre-treatment processes. Then, after cutting in 1 meter length, they were dyed with 3 different dyeing recipes using garment dyeing recipe (Flainox 13854-Quaregna, Italy), and then it was subjected to biopolishing process, followed by a chemical finishing process using 3 different recipes. These samples were compared with untreated samples. The pilling results of the samples obtained using ICI Pilling Box method were statistically evaluated using the MiniTab program. 

Both surfaces of open width single jersey fabrics were passed through (80m/mins.) the singeing machine (Osthoff-Senge, Germany). Since the content of each fabric is different, flame length, the distance between the flame and the fabric and the angle of the flame to the fabric were adjusted.
In the overflow sample dyeing machine having 50kg capacity (Canlar MT Machinery), the pieces of fabrics were washed at 60-700C with wetting agent (1-2g/L), crease inhibitor (1g/L) and Na2CO3 (2g/L) at 1:10 liquor ratio. With this washing step the yellowish color caused by the singeing process was removed. Fabrics were dried at 1200C using stenter (Monforts, Germany), which has 8-chambers. Also, the fabrics except viscose 100% were thermofixed (1950C 25s.) in the stenter to ensure the stabilization of the PET fibers. 
The viscose part of the fabrics was dyed with 1%,3% and 5% reactive dyestuff (Sunufix RED EX) in the garment dyeing machine (15 rpm), (Flainox 13854-Quaregna, Italy), followed by washing process. 
The fabrics were treated with acidic cellulase enzyme (Tanxym CS, Tanatex) for 30 minutes using garment dyeing machine. The enzyme used was deactivated by the temperature change at the end of the process. 
After applying 3 different finishing recipes by garment dyeing machine, the samples were squeezed in the centrifuge (Makinsan, Turkey) and dried at 800C in the tumbler dryer (18 rpm), (Macar Machinery, Turkey).
5g /L Baypret USV (Tanatex) was used for the first finishing process.  Baypret USV is a hydrophilic polymer that does not contain formaldehyde and can self-crosslink without any catalyst. This chemical in the modified polyether polyurethane structure forms a permanent elastic structure around the fibers. Thanks to the elastic structure formed around the fibers, it becomes difficult for the fiber ends to come to the surface and is obtained more soft and bulky touching. In addition, it provides an improvement in rubbing fastness depending on the dyestuff type. In the second finishing process, 3g /L Tanafinish 40119 (Tanatex) was used. It is a silicic acid based cationic chemical. It has been used to reduce fiber piling and snagging. The fiber affinity is not very high and when used in high amounts, it hardens and matters the fabric touch. This chemical shows water and oil repellent properties, especially in synthetic fibers. In the third finishing recipe, 4g /L Baypret USV and 1g /L Tanafinish 40119 combination was used.
Samples were tested at 1800 cycles according to the ICI Pilling BOX (ISO 12945-1: 2000 method). At the end of the period, pilling was evaluated visually with the help of a gray scale. The degree of pilling is determined on a level ranging from 1 (very severe pilling) to 5 (there is no pilling).
According to EN ISO 13938-2: 2000 (Textiles-Bursting properties of fabrics) standard, bursting strengths of the finished fabrics were measured and compared with the untreated ones. After the finished fabrics were washed 5 times, their bursting strengths were again measured using bursting strength tester (TruBurst, England). The pressure was applied to burst the fabrics for 30 seconds (if the fabric doesn't burst, 10 seconds more were applied to the fabrics) with 140mm diameter jaw, which is used for spandex-free knitted fabrics.
In order to observe color differences after finishing processes, both color values of finished and untreated samples were measured and compared by using the spectrophotometer (Datacolor650, SF650, US).
To statistically evaluate 105 data including the pilling results of 5 untreated fabrics obtained in the experiment consisting of 20 different processes, four different models were created on Minitab. Each process was interpreted to Anova Table, Main Plot Graph and Interaction Plot Graphs created from selected models. 
Based on Anova Chart, Main Plot and Interaction Plot Charts derived from the first model, 5 different variables such as singeing, enzyme, dyeing, thermofixing, finishing processes and their two/three-way interactions with each other were statistically examined. In the analysis, evaluation was made based on 4 models, in 1st model, the effect of all process steps on pilling was evaluated one by one, in 2nd model, the effect of binary combinations of process steps on pilling was compared. In 3rd model, triple combinations of processes are evaluated. In 4th model, the effects of 20 applied processes on pilling were compared.
In 1st model, the effects of all variables consist of singeing, dyeing, enzyme and thermofixing one by one were evaluated. A second model was created to statistically evaluate the effect of two-way interactions of singeing, dyeing, enzyme and thermofixing on pilling. In the third model, the effect of triple interactions of variables on pilling was investigated statistically. In the last model created, the effects of each of the processes (20 processes) on pilling were individually examined. 
In order to determine whether dyestuff concentration has an effect on pilling, fabrics were dyed with 1%, 3% and 5% recipes and compared. As the amount of dyestuff increased, the effect of salt and alkaline on pilling was observed. This clearly shows that although there are serious differences between the amounts of soda in the bath, the differences between the pHs are measured very small. As a result, it was observed that dyestuff concentration had no effect on pilling.
To observe the effect of finishing on pilling, three different finishing recipes were applied and pilling performances were examined. The third finishing process for all fabrics used gave the best pilling value. The pilling results of the fabrics after 5 washes, no change was observed.
To observe the loss of tensile strength that may occur in fabrics due to the cellulase enzyme, their strength was measured both after the enzyme treatment and after 5 washes. In both cases, the tensile strength results for all samples were measured above 300kPa. Color change in the samples was measured after finishing processes. 
In this study, considering the presence of PET in the fibers, the problem of pilling is inevitable. To overcome this problem, the effect of the viscose/PET blend ratio, the yarn twist coefficient, pre-treatment process, garment dyeing and finishing processes of knitted fabrics obtained with these yarns on pilling was investigated.
It was observed when using viscose/PET blend fabrics with higher polyester content, in parallel with existing literature, it was sufficient to add thermofixation and removing the enzyme step to reduce pilling while also maintaning cost-efficiency. No substantial change was observed using thermofixation on 80/20 % Viscose/PET ( Fabric 1) and 100% Viscose ( Control Fabric 1). When using fabrics with higher viscose content, pilling could be effectively reduced using enzymes and singeing. In addition to these findings, it was also observed that using polyurethane and silicic acid based treatements in garment dye machines can be effective in changing the treatement effect within tolerance, with good pilling prevention performance.
In the light of the data obtained under this study, to keep pilling at optimum level for fabrics with 50% PET or higher; it is important to follow the singeing, washing, thermofixation, cutting, sewing, garment dying (with at least 80% fullness of the drum), polyurethane finishing alone or in combination with silicic acid applied to garments as a post treatment, centrifuge which enables the removal of excess water on the garment with the effect of squeezing effect (with center principle), drying in drum dryer at optimum speed (18 rpm), ironing and packing.  If the fabric contains at least 50% viscose, enzyme should be added to the process steps instead of thermofixation.