dorlastan in circular knitting

8/7/2019 dorlastan in circular knitting

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Dorlastan inCircular Knitting

Reg. NO 3083

Dorlastan Product Information Circular Knitting

Asahi Kasei Spandex Europe GmbH41519 Dormagen, Germany


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1. Dorlastan in Circular Knitting

Due to its construction a knitted fabric always has a certain stretch and elasticity

even without elastane. The requirements in terms of function and wearingcomfort, not only with sportswear, but also with underwear and outerwear haveincreased. Without using elastane yarns it is not possible to satisfy these require-ments in full. This explains why there are also more and more articles to be foundcontaining elastane yarn in the circular knit fabric collections.

2. Processing techniques

Provided certain conditions are fulfilled, all circular knitting machines are suitablefor processing Dorlastan. There are, however, two rules that must be observed

more strictly than when manufacturing circular knit fabrics without elastane:

1. Identical quantities of yarn must be fed to the knitting needles in the sameperiod of time and in each system.

2. The yarn tension must be kept at a constant level in all knitting systems overa given period of time.

It is of particular importance to adhere to these rules in order to ensure articles ofuniform weight and a consistent quality.

2.1 Classic yarn-feed systems

Normally, every circular knitting machine is equipped with a yarn feeder, i.e. afeed wheel mechanism. It is the task of this feeder to supply each of the knittingsystems with exactly the same amount of yarn. The most common types aretape, storage, and also friction and type feeders, all of which are well suited forproducing knitted fabrics without elastane. These devices are not sufficient forproducing fabrics with bare elastane because:

in the case of the yarn storage feeder problems occur due to jerky winding

and low-tension take off of the thread

in the case of the friction yarn feeder problems occur due to unstable frictionprocesses (glass plate effect)

Yarn feeding mechanisms developed specially for processing bare elastaneachieve far better results.

All of the above-mentioned yarn feeding mechanisms are satisfactory for knittingDorlastan combination yarns, without any additional devices, and producesatisfactory results.


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2.2 Elastane feed systems

Positive feed mechanisms where the unwinding elastane bobbin is driven have

become the most common feed systems in large-diameter circular knitting whenprocessing elastane yarn.The Dorlastan bobbin is driven positively in these delivery systems (e.g.Memminger elastane feeder MER). The Dorlastan bobbins are placed on ahorizontal pair of rollers and pressed against it only by their weight. The twoparallel rollers are driven at the same speed. The device can be stocked with upto four 58 mm bobbins or two 115 mm bobbins. After unwinding, the thread ispasses through an electric stopping device and is then fed directly to the needle.Up to 4 systems/workplaces may be served using one feeder. Multiple positivefeed devices are driven at identical speed via a drive belt, the speed of which iscontrolled by an adjustable width pulley. Adjustment of the pulley can vary the

let off speed of the positive feeders with respect to the knitting machine, whichallows precise control of the elastane tension during the knitting process.

2.3 Changes in yarn direction

When processing bare elastane it is even more essential to avoid unnecessarychanges in yarn direction than it is with conventional yarns. Otherwise uncontrolledvariations in tension may occur, which may lead to irregularities in the fabric, or evenin thread breakage. Conical rolls which can be adjusted to precisely align theelastane yarn path have proven to be best suited for changes in the yarn direction.

2.4 Loop formation and plating

If bare Dorlastan is processed to form a loop it must always be knitted togetherwith a ground yarn. This measure is necessary because there is the risk that theDorlastan thread may break if the knitted fabric is stretched too far. Experiencehas shown that when working with Dorlastan dtex 44 a ground thread with atiter of at least 44 dtx should be used at the same time. Normally, Dorlastan isprocessed with the ground yarn using the plating technique.

Plating means the simultaneous formation of one loop from two threads, so thatone thread will lie on the face of the fabric while the other thread is fed to theneedles in such a way that it forms the back or reverse of the final fabric.

In the case of single-bed circular knitting machines the Dorlastan must alwaysbe fed in via a plating thread guide.

In the case of double-bed machines (ribbing technique or interlock technique),the thread guide can be omitted, if the delayed timing knitting technique(Figure 1) is applied: the Dorlastan is fed immediately to the dial needles viaa guide roller.

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Figure 1: Path of the needle in the delayed timing knitting technique

When the delayed timing knitting technique is applied, the dial of the circularknitting machine is adjusted in such a way that its needles sink the loop laterthan the needles of the cylinder. This changed setting makes it possible to threadthe Dorlastan yarn only into the needles of the dial and to knit it in using theplating technique.

2.5 Setting of the desired quality

Knitting articles can have three different types of elasticity:

longitudinal elasticity transverse elasticity two-way stretch (bielastic)

The desired type of fabric can be achieved by choosing the appropriate knittingmachine (single- or double-knit), knitting construction and determining the yarnfeed (e.g. every 2nd system knits Dorlastan in addition to the ground thread).

If Dorlastan is incorporated in a rib construction, the finished fabric will havemainly longitudinal elasticity. Articles with predominantly transverse elasticity areobtained with double-knits by feeding Dorlastan either to the dial needles only orto the cylinder needles only. Bielastic articles are preferably produced as singleknits. When using Dorlastan with each knitting system, nearly identical elasticityand recovery force can be achieved for the longitudinal and the transversedirection.

Since fabrics containing Dorlastan are expected to have higher extensibility andgreater recovery forces, it is necessary to set larger stitches. In addition, a muchfiner ground yarn is normally used. If the fabric is knit too tight (with very small

stitches or too thick ground yarn) the Dorlastan yarn is prevented from contractingthe fabric to the desired extent.


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Simultaneous yarn feed

Loop forming point

delayed yarn feed

Loop forming point

Path of the needle with


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The desired elastic properties of a fabric highly depend on the use of a Dorlastanyarn with the appropriate titer. In addition to this, the knitting machine can beadjusted in various ways, e.g. adjustment of the height of the dial, sinking depth,

rob timing, yarn tensile strength. For example, if a higher recovery force isdesired for a certain construction, this may be achieved by increasing theDorlastan tension, using the existing machine gauge. If the fabric is then giventhe same final dimensions and weight per m2 during finishing, its extensibility willdecrease. If the resulting extensibility is no longer adequate, a coarser yarncount should be used.

Further possibilities include incorporating Dorlastan into every second, everythird row, etc. This way, many different types of knitwear can be produced fromlightweight fabrics for underwear to heavy fabrics for riding breeches.

When working with Dorlastan one has far better possibilities to modify certainproperties and influence the fabric with width, weight, volume, extensibility,recovery force, appearance and characteristics than with conventional yarns.

2.6 Quick test of fabric quality

With knitted fabrics that contain elastane it is often not possible to predict thequality of the final fabrics from the gray goods with the necessary degree ofcertainty, as it is with fabrics made of conventional yarns. Nevertheless, thetechnical data for the gray goods and the machine settings should always berecorded as is the usual practice for all knitted fabrics. To get a first idea of

the elastic properties, depending on the article, a small cutting of the grey fabricshould be subjected to very intense steaming or, better still, hot water treatmentor boiling off. This completely relaxed specimen gives the experienced knitter aclue of the properties the final fabric is likely to have, enabling him to also givethe finisher details of the necessary overfeed and width setting on the tenterframe. The overfeed and the width setting in combination with the settingtemperature adjusted to the materials determine the longitudinal and transverseextensibility and influence the recovery force. This does, however, not apply tocircular-knit elastic welts such as waistbands for underwear. These articles can-not and will not be heat-set. The properties of the final article depend primarilyon the knitting construction of the fabric, the titer of the ground yarn and thetension and titer of the Dorlastan thread.

Only the finished fabric will show whether all the desired properties have beenachieved, and will provide information on whether and what technicalmodifications to the grey good are required.


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2.7 Processing of elastic combination yarns

Combination yarns are generally only used today if no suitable feed devices areavailable for processing bare elastane.Combination yarns are preferably used for knitting constructions where theelastane yarn lies on the surface, as here the possibilities for a bare processingof elastane are still very limited.

3. End Uses

Up to now the use of Dorlastan in circular knitting has been considered from atechnical point of view. Let us now turn our attention to the knitted articlesthemselves. Given the large variety of end uses, it appears to be recommended

to distinguish between the various sectors of use according to the articleproperties desired. The main fields of application are:

3.1 Power Stretch articles3.2 Trouser material qualities3.3 Outer wear3.4 Swimwear3.5 Sportswear3.6 Body linen3.7 Waistbands for underwear3.8 Welts

The articles of these different sectors all have their specific properties. Due tothe influence of fashion on the numerous fields of use of knitted fabrics theboundaries between the various sectors are flexible, e.g. body linen indoorwear nightwear (color style).

3.1 Power-Stretch articles

For articles with shaping properties like corsetry, Dorlastan yarns of medium tocoarse range, i.e. approx. 133 dtex and above are required. Such articles need

high recovery forces in both longitudinal and transverse directions. However,normally, the longitudinal extensibility need nor necessarily be as good as thetransverse one.

Example 1:Highly-functional fabric made of a uniform ground yarn with Dorlastan plating ofevery stitch course.Machine: Single-knitGauge: 18 EMaterial: Polyamide dtex 78 f 68 x 2

Dorlastan dtex 133Construction: RL plating of every stitch course


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3.2 Trouser Material qualities

Trouser fabrics, e.g. for riding, require little extensibility of approx. 2030% but a

high degree of elasticity in both longitudinal and transverse directions to preventthem from becoming baggy.

Good longitudinal extensibility is obtained by knitting Dorlastan together withthe ground yarn in a rib course.

Example 2:Ribbed fabricMachine: InterribGauge: 18 EMaterial: PA dtex 156 f 34

Dorlastan dtex 44Construction: Ottoman

3.3 Outer wear

Elastic qualities are also used to a large extent in outer wear. The yarn insert ishighly varied in the hard fiber yarns used. The customary extensibilities for thisarea of use are achieved by using Dorlastan 22 44 dtex.

Example 3:Longitudinal and transversal elastic quality with innovative PA yarn.Machine: Single-knitGauge: 28 EMaterial: Meryl Satin dtex 88 f 40Construction: RL plating of every stitch course

3.4 Swimwear

Fabrics with high extensibility in longitudinal and transverse directions are

required in this sector.

They must be stretchable by 100% in both directions. Other qualitycharacteristics are:

average recovery forcein general, fabrics are used that do not have any figure-shaping properties.

different weightsThe weight ranges from between 100 and 200 g/m 2 depending on the finaluse, e.g. swimwear for competitions, leisure swimwear or beachwear.


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The exterior of the textile consists of highly absorbable materials such as cotton,wool, viscose, modal or combinations of such. These may absorb the excesssweat, which however is now not stored near the skin until vaporization takes

place.The functional wear is therefore found to be dry and more pleasant longer duringtimes of extreme sweating than conventional clothing textiles.Besides the physiological benefits of the functional clothing Dorlastan signifi-cantly increases the wearing comfort and the well-being of the person wearingthe clothes, as it gives the tightly worn clothes the necessary fit and stability ofform with simultaneous elasticity and extensibility. Therefore, the articles ofclothing are not felt to be unpleasant or too tight.

Example 6:Functional wear

Machine: InterribGauge: BW Nm 80/1

Dorlastan dtex 33PES dtex 100 f 128

Construction: Triple plating

3.6 Body linen

Body linen and underwear should be of low volume, i.e. the contours of a panty,for example, should not be visible under tight trousers.

These fabrics are produced mainly with circular single-knit machines with agauge of E 28.

Example 7:Body linenMachine: Single-knitGauge: 28 EMaterial: Cotton (Nm 120/1)

Dorlastan 22 or 33 dtex plating in all courses

Construction: RL

Example 8:Fine textile qualityMachine: Single-knitGauge: 28 EMaterial: PA 6.6 dtex 40 f 40

Dorlastan 22 dtexConstruction: RL


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3.7 Waistbands for underwear

Qualities of waistbands for underwear should besides a high extensibility (transversal

direction) of approx 200 - 250% have a very good recovery force. Dorlastan dtex 320is highly suited for this. Good results can be achieved in fine rib qualities, if Dorlastandtex 160 or 240 is used in each course. At the same time, the articles with waist-bands can be prevented from tending to roll too much during the clothing process.

Example 9:Fine rib waistband for underwearMachine: Circular knitting machineGauge: 15 EMaterial: Cotton 200 dtex (Nm 50/1)

Dorlastan dtex 240

Construction: RR. Dorlastan knits additionally in every system, either circular ribor circular cylinder

3.8 Welts

Collars, borders, trouser finishes and waistbands should always lie gently next tothe skin and not wear out when worn. Therefore, border goods should not havestretch-like properties but merely a comfortable elastic property.

Example 10:Fine ribbed goodsMachine: Circular knitting machineGauge: 18 EMaterial: Cotton dtex 167 (Nm 60/1)

Dorlastan dtex 44Construction: RR, Dorlastan also knits to cotton in each 2nd

knitting system, however only circular rib

If you have any questions concerning circular knitting please contact ourDepartment Marketing Dorlastan who will be pleased to beof assistance:

Dormagen, Germany phone +49 21 33 / 51-41 31Bushy Park, USA phone +1 84 38 20-65 10


dorlastan in circular knitting

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