Elastic covered yarn

An elastic covered yarn the core of which is a wrapped yarn consisting of elasthan filament yarn having polyamide, polyester or viscose filament yarn as the sheath material, and which may be covered with different materials. This yarn has advantages in its properties and in processing compared to those covered yarns, the core of which is a bare elasthan filament yarn.

This invention relates to an elastic covered yarn, the core of which is a 
wrapped yarn of elasthan filament yarn having polyamide, polyester or 
viscose filament yarn as the sheath material. The wrapped yarn which is 
used as the core may be covered with different materials, for example, 
cellulose, mixed yarns of cellulose/polyester or 
cellulose/polyacrylonitrile, wool, regenerated cellulose fibres (viscose) 
and mixtures with polyester or polyacrylonitrile. 
Elastic covered yarns are known which comprises a bare elasthan filament 
yarn as the core and textile fibre yarns as the sheath material. Cloths 
made from such covered yarns are generally flexible, i.e., articles made 
of these fabrics exhibit elongations even under a low strain, and these 
elongations cause complications in the course of further processing. 
Moreover, it is known that textile sheet structures made of such covered 
yarns have a low modulus and thus generally have a lower resiliency. As a 
result of the ready deformability, the final quality of such covered yarns 
is unfavourably influenced in connection with irregular yarn tensile 
forces due to crepe effects. ("Bolder-stellen"), to fluctuations in width 
and to tight threads. The effect of these disadvantages in the production 
and processing of the known covered yarns is that these materials have not 
had the desired success in the production of elastic fabrics. The former 
elastic covered yarns have also been particularly unsatisfactory for piece 
dying. This is also the case with the elastic yarns which are described in 
British Pat. No. 949,326 and in U.S. Pat. No. 2,024,156 in which three 
yarns are twisted together to obtain a substantially three-component ply 
yarn having a elasthan filament yarn as the core and a spiral yarn or ply 
yarn structure. 
It has now been found that the above-described disadvantages may be 
substantially avoided by using a wrapped yarn which has already been 
stabilized and consists of stretched elasthan filament yarn around which 
polyamide, polyester or viscose filament yarn is alternatively wound, 
instead of a bare elasthan filament yarn for the production of elastic 
covered yarns. 
Covered yarns which have the above-described wrapped yarns as the core may 
be produced on regular ring spinning frames, unlike previously known 
covered yarns, without requiring the additional delivery mechanism which 
is essential for stretching when bare elasthan is used. 
As a result of using elasthan wrapped yarns as the core in the elastic 
covered yarns, not only is a more stable yarn structure obtained, but also 
due to the additional wrapping of the elasthan yarn with fine filament 
yarn, covered yarns of this type have a higher modulus which is now 
required in many areas of use. Thus, sheet structures produced therefrom 
are less susceptible to undesirable and frequently uncontrollable 
deformations and have a higher inherent stability. Handling elastically 
extensible articles of a higher modulus, in particular, facilitates the 
outcome of the process in the course of ready-made production into 
articles of clothing. It has also been shown that the covered yarns 
according to the present invention which have a wrapped yarn core and an 
elastic extensibility of from 20 to 30% which is presently required in 
certain areas of use generally not only have a more stable structure, but 
mobilize a high resiliency when stretched due to the higher absorption of 
force. In operating terms, i.e., during processing of the covered yarns 
according to the present invention, a more favourable behaviour is 
established as a result of a lower thread break number, particularly when 
sized covered yarns according to the present invention are used as the 
warp in the production of fabrics. 
The possibility which is afforded depending on the respective intended use 
of varying the extensibility ranges by a corresponding yarn structure 
provides the processor with a greater spectrum of possibilities for 
shaping textile sheet structures without the desired appearance of the 
product being impaired by considerable interferences in the yarn 
formation, for example by replacing a single yarn with an elastic ply 
yarn, or changing the yarn optics as a result of a higher twist. 
The covered yarns according to the present invention having a wrapped yarn 
core also provides an improved overall final quality of the finished 
products, because the consequences of undesirable yarn deformations in the 
processing operation are less serious due to the higher modulus and the 
optics of the finished products also correspond to those of an inelastic 
product. 
The covered yarns according to the present invention contain a wrapped yarn 
consisting of a elasthan filament yarn having a titre range of from 30 to 
200 dtex, preferably from 45 to 160 dtex around which polyamide, polyester 
or viscose filament yarn of a titre range of from 15 to 90 dtex, in 
particular from 22 to 78 dtex is wound simply or crosswise. 
For the production of the wrapped yarn 45, 80 or 160 dtex elasthan filament 
yarns around which 22, 33, 50 67 or 78 dtex polyamide or polyester 
filament yarn is wound once or twice in a simple or crosswise manner are 
preferred. The sheath materials for the production of the covered yarn are 
within the number range of from 40 to 10, preferably from 30 to 12. 
A particular advantage of the covered yarn according to this invention is 
its applicability in piece dying, because the covering of the wrapped yarn 
by the sheath material is so complete that the wrapped yarn which may 
possibly not have been dyed does not shine through.

In the drawing, an elastic covered yarn 10 according to the present 
invention is depicted wherein a yarn core 11 of a stretched elasthan 
filament yarn has wrapped thereon a polyamide, polyester or viscose 
filament yarn 12. Such wrapped core is further covered with a covering 
material 13 of cellulose/polyester or cellulose/polyacrylonitrile, wool, 
regenerated cellulose fibres or mixtures with polyester or 
polyacrylonitrile. 
EXAMPLE 
A twill was produced from an elastic covered yarn of the following 
structure: 
Core: 
Wrapped yarn consisting of 80 dtex elasthan single covered with 22 dtex f 
7.times.1 Nylon, (900 T/m S) 
Covered with 40 dtex.times.1 (=Ne.sub.c 15/1) cotton, 
effected yarn thickness, stretched.apprxeq.45 tex; =Ne.sub.c 13.2 
This elastic covered yarn was used as a warp material having 64 ends/inch 
in the finished fabric, after the yarn had previously been sized using 
normal products suitable for sizing cotton yarns. A textile fibre yarn 
consisting of polyacrylonitrile 62.5 tex.times.1 was used as the weft 
material. Set of the weft 61 picks/inch in the finished product. Weave 3/1 
twill, m.sup.2 weight 280 g. 
The grey goods were washed and shunk, followed by a surface fixing with 
subsequent piece dying of the cotton using cellulose dyes, and then a 
final chemical finish specific to the article was applied. A denim-like 
fabric was thus obtained having an extensibility of from 25 to 30% which 
exhibited a high recoil capacity and a high force absorption when 
stretched.