Pamuk iplik özelliklerinin örme kumaş kalitesi üzerine etkileri

Abstract

Boyalı örme kumaş kalitesi hakkında üretime başlama dan önce, iplik özellikleri incelenerek fikir sahibi olunabilir. Değişik partilerden olmak üzere 12 tip pamuk ipliğinin numara, büküm, düzgünsüzlük, mukavemet, olgunluk ve lif uzunluğu değerleri incelenerek, yuvarlak çorap maki- nasında örüldükten sonra reaktîf boya ile boyanmıştır. Boyalı numunelerin renklerinin açıklık/koyuluk, gri skala değerleri Datacölorda ölçülmüştür. Genel olarak olgunluk değeri iyi olan pamuklarda boyama iyi sonuç vermiştir. İplik özellikleri içinse kısa elyaf oranı arttıkça büküm katsayısının (?Ce) da arttığı iplik numara değişiminin yükseldiği, düzgünsüzlüğün arttığı, mukavemet değerlerinin ise kötüleştiği görülmüştür. Ayrıca neps miktarı da mukavemeti olumsuz olarak etkilemekte, efektif uzunluğunun artışı ise kopma uzunluğu (RKM) değerini yükseltmektedir.

The most popular systems of spinning that have been developed in recent years are RING and 0-E ROTOR spinning sytems. The properties of cotton obtained through these systems differ according to the type of the production. In Rotor system, yarn can be obtained in more twisted form, bulkier and cleaner in the quality of carded, yarn, and in Ring system finer count and in the quality of co.mbed yarn. By the way in recent years, many investigations have been- made on O.E-Rotor system and tried to obtain yarn in the quality of the Ring yarn by combing. Knitted fabric is conducive to health and is comfor table, it can be made in various textile materials and in weights and styles for all seasons and climates. It is suitable for both old and young. Knitted fabric is made from various yarn and especially cotton yarn is very important. In cotton wear both carded and combed yarn are used: The carded yarns are for light medium and heavy weight of knitted underwear, and the combed yarns are generally for light summer weight. The art of-knitting consists of forming with a single continuous thread of yarn individual loops and joining or chaining each loop to its neigb.ba.rine loops. The loops in a knitted fabric form a series of chains lengthwise to the fabric Each chain is called a wale and defined as "a series of loops running lengthwise of the fabric, all made by a single needle". The loops also from lines across the fabric at right angles to the wales. These are called courses. Knitting yarns are usually manufactured from avarage or better than average quality cotton, in order to make a Commercially satisfactory fabric. vm Satisfactory-knitted fabric may be produced only from well-made yarns. If the variations in yarns persist, the fabric will show decided bands, stripes, or rings as a result of the different textures produced by the differing yarn counts. The characteristics generally desired in a knitting yarn are uniformity, flexibility, elasticity, smoothness, and strength, twist. Many knitted fabrics are expected to fit the wear snugly, and one great advantage of knitted garments lies in their ability to stretch enough to fit many different weares comfortably. Most of the defects of ready-m«ade clothes of knitted fabric set apart, are mostly knitting defects and the reason of these defects are mostly yarn defets. For these reasons, it is quite important to examine the properties of cotton fibre and yarn. The fineness and longtotude of cotton differ from type to type and this restricts the use of cotton. Cotton dimensions vary with the type of cotton. The Indian and American fibres being shorter and the Egyptian and Sea Island Fibres longer. Usually a long fibre is correspondingly finer. From the viewpoint of cotton manu facture the finer and longer the fibre the more suitable it is for making high quality materials. Maturity of the fibre is also important. Because it is quite effective on the affinity for dyes. The affinity of celluLose fibres for dyes is much influenced, by the way in which the cellulose molecules are packed together within the fibres. Usually a cellulose fibre such as cottons contains both erystaline and amorphous regi ons. As much as, the crystalline increases, the affinity for dyes decreases. Mature fibre has a thick wall and it appear rod-like with no continuous lumen. The wall thickness of dead fibres is one-fifth or less of the maximum ribbon with. Dead fibres vary from flat ribbons. xx Cottons that are classed as immature are objectio nable mainly because of their liability to the formation of neps which unless removed by combing, survive all processes through to the yarn, when the appear as unsight ly specks. Immaturity below a certain level leads to insuffici ent spinning and excessive end- breakages. In this study it is observed that when the maturity level decreases, unevenness increases. The fibre strength effects directly yarn strength. But the yarn strength is not equal to the strength of the fibres which forms in yarn. If the amount of short fibres increase in cotton yarn, the strength and hairiness decrease, unevenness and twist increase. When the twist increases, the handle become harder. In this experiment when the effective fibre lengt increases. (RKM) increases and in addition, short fibre percentage increases, elongation of the yarn decreases. Yarn count shows the yarn fineness degree. The variation of the count on the yarn lengthwise causes unevenness. The yarns examined in this study show acceptable the mean yarn count and when the yarn count variation increases, unevenness also increases. It is also observed that when the short fibre percentage incre ases, the yarn count variation increases. Yarn unevenness which is important factor that effect the quality, can cause periodic defects all over the fab ric surface. (Figure 2) The amount of the waste in cotton plays an important role in determing the cotton quality. If the waste in cotton such as plant, sand, etc are not seperated these cause machien faults, trash increase and mainly fabric defects waste amount can be determined by various met hods. Especially in knitted fabrics produced by circular knitting machine, different types of cops yarns that become one after another appearce as defect. x (a) (b) (c) (d) (e) (f) Fig: 1. Cotton Swollen In 18% Caisstic Sodo (a) Normal fibre (b) Normal fibre (c) Thin- walled fibre Rod-Like appearance, with hardly any lumen. Rod-Like appearance, the lumen may be seen in places but is not continu ous- Convoluted form, with wall thickness greater than 1/5 of the max. ribbon witdth (d) Thin-Walled fibre Non-convoluted form wall thickness greater than 1/5 of the max. ribbon width (e) Dead fiber Moderate frequency of convolutions wall thickniss less than 1/5 of the max. ribbon width. (f) Dead fibre Shows frequent convolutions wall thickness less thon 1/5 of the max. rib bon width. xx It is clear that, in order to produce high quality fabric, fibre and yarn properties should be konwn. For this reason, this research has been carried out. In order to determine yarn and fibre properties, 12 types cotton yarns from different parties are examined by appl ying many tests. After fibre length and maturity, yarn count, twist, strength, unevennes are determined, the yarns are knitted by circular knitting machine and then they are dyed by reactive dyes. After dyeing the darkness/yield, and grey scale values of the samples are measured by Datacolar. During colour tests, sample A is accepted as standart. The results obtained from this research are generally parallel to the other researchers. The aim of the research is the dyed fabric quality by testing the properties of yarn. But, it is not always possible to estimate the yarn performance and the fabric quality by only conside ring general yarn properties. This fact has been consi dered in this thesis and the fibre lengths and maturities of different yarns were especially measured in order to enlighten this point. In general; in the cotton having good maturity, the variation (cv %') of rupture strengt is low. With the increase in short fibre rate, rupture strength elangation (E %) decreases. Again, in this type of yarn, twist multipler (oCe) is high. Whenever, unevennes is high, (CV %) of rupture strength is high. When the neps level increases, rupture strength variation (CV %) increases. In the type of D, (RKM) value is max, but short fibre rate and unevenness levels are also max, but the point is that the maturity level is high. Incre asing unevenness causes neps and thin-thick places increase. Sample A is taken as the standar to the results of dyeing. In the cotton much more mature than A, darker colour is obtained and this is the result that is generally obtained. It has been given the relationship between fibre properties, and the influence of fibre preperties on yarn properties. The yarn count variation is acceptable. It is observed that when the yarn count varition (CV %) increases, rupture strength variation increase. As the twist increases, the yarn becomes stronger. In contrary some types having high twist level have insufficient (RKM) value, but the point is in these types neps level is high and maturity level is low. xxi Fig:2. Fabric Knitted From Yarn Which Has Count. Variation. Unevenness can be caused from yarn count variation thin and thick place or neps on lengthwise of the yarn. After dyeing thin places seem in light colour but the thick places seem in dark colour. After the knots are cleared away, there can be seen holes Although yarn hairness is not criterion determing the quality of the yarn, its importance increases every day. It is generally an unwanted characteristic forms by the fibre end that comes out of the yarns. It generally originates from production, but can be prevented by inc reasing twist or by using long fibres. Yarn strength is influenced fibre strength, unevenness and maturity, for a strong yarn these properties must be obtained in the best conditions, besides, if given twist exceeds the amount of critical twist this causesunwanted results. Yard strength is a very important property for quali- fed fabric and the efficiency- of production. For this reasen it is important to know in which quality the yarn is, carded or cg.mbed. This can be decided by stapel diag ram that is obtained through fibres from the yarn. Alt- houg this is a difficult and discussable method, it is the only valid way of determining the fibre length from the yarn.