What is Yarn Texturing?
Texturising or texturing is the process of formation of crimp, loops, coils or crinkles in filaments to impart special textures. The texturising process was originally applied to artificial fibres to reduce such characteristics as transparency, slipperiness, and the possibility of pilling (formation of small fibre tangles on a fabric surface). Yarn texturing is a process which is used in the textile industry to modify the properties of synthetic fibers, such as polyester, nylon, and polypropylene, to make them more like natural fibers in terms of appearance, texture, and performance. Texturising renders yarns more opaque, improves appearance and texture, and increases warmth and absorbency. Thus texturising is increasingly important in textile production, not only in yarns for weaving and knitting fashion products, but also for carpets, furnishing fabrics and a variety of technical textiles.
We can define a textured yarn in the following way, a multifilament yarn that has been processed after extrusion spinning to introduce durable crimps, coils, random loops or other fine distortions along the lengths of the filaments, primarily giving the yarn increased bulk with or without increased stretch.
In the 1950s, a new branch of the textile industry – the texturing of continuous filament yarns became established as a commercial success, although, at that time, it was more common to talk of ‘bulked yarns’, ‘stretch yarns’ and ‘crimped yarns’.
Benefits of Yarn Texturing:
Texturising improves the use characteristics and hygienic properties of synthetic yarns. One of the most important advantages of textured yarn is that it gives good comfort as the result of the air entrapped between the interstices of the yarn. Besides, there are also numerous benefits of yarn texturing, including enhanced elasticity and stretch, increased bulk and loft, and improved softness and comfort, making them ideal for garments and home textiles.
Synthetic yarns can also be textured to make them hairier and softer like conventionally spun natural fibres. Texturing can even be used to change how stretchy a yarn is. Texturing provides in yarn better moisture management, improved aesthetics, greater dimensional stability, and enhanced durability, making fabrics more visually appealing and long-lasting.
Different Texturing Methods of Yarn:
There are numerous methods for yarn texturing which result in yarns and resultant fabrics with different textures. Various texturing methods are practised, most of which are only suitable for thermoplastic contimuous filament yarns as they involve heating the filaments to achieve the texture profile and cooling to retain it. Among several texturising methods, false twist texturising and air-jet texturising are very prominent technologies. The methods commonly referred to are the following.
1. False twist texturing:
False twist is the action by which twist is inserted into a yarn at the position of contact with a twisting device, and is then removed by the same device as the yarn leaves contact with it. False twist texturing is a popular method of texturing filament yarns that works on the principle of twist–set–detwist. In this process, a flat filament yarn is twisted, set and untwisted to impart required crimp, stretch and elasticity. The continuous filament yarns are twisted and heated simultaneously and then untwisted when cooled, thus loosely retaining the heat-set helical shape of the twist.
When filament yarns made from thermoplastic materials are heat-set in a twisted condition, the deformation of the filaments is ‘memorised’ and the yarn acquires greater bulk. Hence false twist texturising produces very voluminous and highly elastic yarns that find their utility in fashion textiles, tights/stockings and other lingerie as well as in technical end-uses.
2. Air-jet texturing:
Air-jet texturing has become increasingly important because of its capacity to process continuous filament yarns of any polymer type. In air-jet texturing, thermoplastic or non-thermoplastic filament yarns are overfed into an air-jet nozzle, wherein the individual filaments with the action of the air-jet get tangled to produce the desired texture. The crimp comes into being through the retraction that happens after the air-mechanical deformation and these yarns exhibit maximum level of bulk as compared to other texturised yarns. With post-thermosetting in a heater the yarn builds up higher crimp stability and reduced shrinkage. A natural, cotton-like look is representative of such yarns.
Air-jet texturing is also capable of providing products with aesthetic characteristics (tactile handle) superior to most other texturing processes. It can be used to process FDY/FOY (to give air-textured yarn, or ATY) or with a pre-drawing stage in an integrated draw-texturing system to convert POY to a drawn-air textured yarn (DATY).
Air-jet texturised yarns are extensively used for home textiles, sportswear for technical applications.
3. Stuffer box:
In this process the filaments are stuffed in a confined space of a heater chamber which is called as a stuffer box. The filaments pass through a heated box at a faster rate than they are removed (known as overfeed). This forces them to adopt a random wavy, crimped pattern while heated. The textured form is set by subsequent cooling. In the stuffer box, the filaments are heat set in their crimped from and then they are withdrawn. These yarns are soft, bulky and offer good absorption properties and have less extensibility.
4. Knife edge:
The filament yarn is heated and pulled across a blade at an acute angle. When the yarn is cooled and released, the retained internal stresses in the filaments cause them to collectively adopt a spring shape or curled ribbon appearance, i.e. the profile is heat-set.
5. Knit-deknit:
Filament yarns are knitted into the shape of a small-diameter tube and heat-set (i.e. heated and then cooled). The yarns are then de-knitted, giving them a wavy configuration.
Yarns used to create other than comparatively smooth textures in fabrics may be achieved by the following methods:
Modification in the Spinning Process of Single Yarns:
Various textures that results from modifications in the spinning process of simple yarns are identified by such terms as:
- Boucle yarn is one of the most widely used fancy yarns. It is characterized by an effect yarn forming tight loops that project from the body of the yarn at regular intervals.
- Slub yarns are made by varying the tension of yarn twist at regular intervals to produce soft, thick elongated low twist areas (slub).
- Snarl yarn is made by twisting at one time two or more yarns held at different tension. The effect yarn forms alternating unclosed loops along both sides of the core yarn.
- Spiral or Corkscrew yarn is made by twisting together two yarns of different thickness and twist, one soft and heavy and the other fine. The heavy yarn is fed faster than the fine yarn and winds around it in a spiral formation.
Modification of Thermoplastic Filament Yarns:
Variations in texture can be done by application of heat to the thermoplastic yarns by texturization or crimping. Texturization is the process by which filaments are distorted to impart crimp, curl, coil and loop structures along their length to achieve bulk, stretch and absorbency.
In texturization process, untextured yarns are heated to plastic condition after it was distorted by texturing element (spindle, gear, knife etc.). Then they are cooled to retain the required shape. Textured yarns are basically three types:
Bulk Yarn: Mainly Gear crimping, Stuffer box and Air Jet methods are used to produce these yarns of increased bulk but minimum stretch. These processes can increase bulk from 100 to 300 percent. They are used as carpet yarns and in sweater fabrics. The resultant fabrics are usually soft with some degree of bulk and warmth but are light in weight.
Stretch Yarn: False twist and Edge crimping method is used to produce this type of yarns having 300 to 500 percent elongation. In the first method, the yarn is twisted, heat-set, and untwisted to get a coiled yarn. In the second method, the hot filaments are drawn over a knife like edge, which flattens one side and causes the yarn to curl. They are used in swimsuits, lingerie, stockings, one-sized garments where a form-fitting resilience without pressure is required.
Modified Stretch Yarns: They are between the above two in stretch properties (about 10 to 15 percent). They are made in basically the same manner as stretch yarns except for a final step of heat-setting the yarn after the untwisting step.
Conclusion:
Texturising is the modification process of regular structure of synthetic filament to somewhat random structure by the formation of folds, loops, coils or crinkles. The texturised yarns have bulk and stretch. Texturising methods make yarns more opaque, improve look and touch and boost warmness and absorbency. The texturised yarns are synthetic uninterrupted filaments, modified to impart bulkiness, soft feel and crimp.
References:
- Technical Textile Yarns: Industrial and Medical Applications Edited by R. Alagirusamy and A. Das
- Textiles and Fashion: Materials, Design and Technology Edited by Rose Sinclair
- Texturising: Defects, Causes, Effects, Remedies and Prevention through Quality Management By H. V. Sreenivasamurthy and B. Purushothama
- Yarn Texturing Technology By J W S Hearle, L Hollick and D K Wilson
Founder & Editor of Textile Learner. He is a Textile Consultant, Blogger & Entrepreneur. Mr. Kiron is working as a textile consultant in several local and international companies. He is also a contributor of Wikipedia.
