US 3431814 A
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March 11, 196 9 BOEHM Q 3,431,814
SOFT-FEEL, LONGSTRETCH, ELASTIC BRAID Filed Oct. 25, 1967 INVENTOR. ERNEST ROBERT BOE HM ATTORNEY United States Patent 5 Claims ABSTRACT OF THE DISCLOSURE A long-stretch elastic braid in which the braiding has textile fibers, which are braided along and around elastic threads, such as rubber or spandex threads, pass alternately under two or more threads from the other diagonal direction to permit a braid which can be stretched 100% or more without breaking the textile threads, the threads being made of a special plied yarn made up with synthetic materials, such as nylon. One yarn is tightly twisted, for example about 140 twists per inch, in one direction, for example clockwise, and is then heat set, followed by untwisting in the opposite direction. The second yarn is prepared in exactly the same way but with the twist reversed, that is to say, first counterclockwise. After the yarns have been twisted, heat set, and untwisted, they are then plied together into a single yarn with a fairly low twist, for example 5 turns to the inch in either direction. The greatest stretch possible with long-stretch elastic braid is retained, but the somewhat hard feel of the ordinary long-stretch braid is replaced by a very soft, textured feel, which is desirable when the braid is to be worn in contact with the human skin.
Background of the invention Long-stretch elastic braids are well known and have been made with braids formed by diagonal yarns which alternately pass under two or more braids of the opposite diagonal and around the elastic threads, which may be considered as warp threads. The resulting braid can stretch, for example 100% or more, without rupturing of the braided yarns and is used extensively where an elastic braid is required which can stretch a large percentage of its relaxed length. At the same time, the rubber or other elastic warp threads are completely covered as the braided yarns surround them in the braiding operation.
However, long-stretch braids have had one drawback when used for articles that are to be worn next to the skin. The smooth synthetic materials used in braiding, such as for example nylon yarn or other synthetic yarns, are smooth and shiny and have a somewhat hard feel, which is often considered objectionable by wearers. Also, there is another problem presented by the fact that the synthetic yarns, which are in general continuous filament yarns, do not absorb moisture readily and, therefore, when worn next to the skin do not absorb perspiration readily so that they can become damp with a corresponding unpleasant sensation. Nevertheless, the tremendous degrees of stretch and the great strength of the continuous filament, synthetic yarns have made the long-stretch braid so desirable from many standpoints that it is very extensively used in spite of the drawbacks set out above.
If it is attempted to increase absorbency by using spun synthetic yarns, the lower strength at the enormous degrees of stretch to which long-stretch braid may be subjected has rendered this approach to the problem unsatisfactory. Therefore, the long-stretch braids used at present still employ the continuous filament, synthetic yarns for the textile yarns of the braid, and the feel and poor ab- "ice sorption characteristics have been, of necessity, tolerated to obtain the other desirable properties of the braids. This presents the not unusual situation where a good product is a compromise, some very valuable or even essential fea tures being obtained with certain offsetting disadvantages which make the compromise article fall short of the ideal.
Summary of the invention The present invention produces long-stretch elastic braids, the braiding being formed in the same manner as in the past, but provides good moisture absorption and a very desirable soft feel without any sacrifice of strength or other desirable properties.
The present invent-ion utilizes a continuous filament, preferably a moderately soft multi-filament, synthetic yarn such as nylon, which has been developed for knitted hosiery and is described and claimed in the patent to Russell, 3,210,964, Oct. 12, 1965. This yarn is extraordinarily effective for hoisery which requires high stretch in a least certain zones and has achieved a well deserved commercial success. The yarn used by Russell is prepared in a peculiar way. A multi-filament, for example a 3-filament, continuous filament nylon yarn is subjected to an excessive twisting operation, for example about twists per inch. While in this highly twisted form it is subjected to heat setting, for example, by passing rapidly through a short zone at a temperature of around 400 R, which causes the highly twisted yarn to become heat set. The yarn is then untwisted the same number of twists. Another nylon yarn of the same kind is subjected to excessive twisting in the opposite direction, heat setting, and then untwisting. One of the yarns is said to have a Z twist and the other an S twist. On relaxation each of the untwisted yarns tends to have a residual tendency or memory to twist in the direction in which it was heat set. Hosiery is then knitted with alternate rows, one of one kind of yarn and the other of the other. The hosiery lends itself to being stretched longitudinally and so a single size of stocking can be used for different sizes. The foot can be knitted in the same manner except for the heel and toe, which are knitted with a plied yarn, one Z twist and one S twist with a very small number of twists in the ply, for example 5 to the inch. Of course the Russell stockings are not provided with stretch braid and in fact have no elastic warp or other threads, the whole of the stretchability resulting from the residual tendency of the heat set yarn to twist on relaxation.
The present invention uses the plied yarn which Russell employs for his heel and toe as a yarn to form a long stretch braid about rubber or spandex warp threads. A stretch braid is produced which has as great or greater properties of stretch than the ordinary long stretch braid, and it has two other very desirable characteristics which the ordinary long-stretch braid does not possess. First, the feel of the long-stretch braid is soft in spite of the hard elastic cores and has a very desirable feel for materials which are to be worn next to the skin. Secondly, the stretch braid has a greater capability for absorption of perspiration as the yarn is not smooth, shiny, continuous-filament, as in the case of ordinary long-stretch braid. In spite of the desirable feel and behavior toward perspiration absorption without clammy feeling, the long-stretch braids of the present invention are just as durable as the relatively harsher, poorly absorbent long-stretch braids that have been used hitherto. An elastic braid is, of course, not described in the Russell patent, and it is noted that the plied yarns which are used in the present invention are described by Russell for use in the heel and toe of his greatly improved stretch hosiery, these being portions, particularly in the case of the toe, where extreme stretch is not important as in the leg portion of the stocking.
Nevertheless, when used in an entirely different type of fabric from the knit hosiery of Russell, the plied yarn provides enormous stretch with the highly desirable characteristics of feel and moisture absorption, which have been described above.
The range of twists prior to heat setting is not sharply critical and may, for example, vary between 100 and 150 twists per inch, with 140 twists giving an excellent product, as is the case with Russells all-textile yarn which he uses in his improved hosiery.
It is preferred to use nylon yarn in the present invention, but it is, of course, possible to use other thermoplastic, continuous-filament yarns which are capable of heat setting in a twisted form. For example, the yarn may be a polyester yarn, and of course blends are useful. It should be noted that the invention is, however, strictly limited to the use in long-stretch braids of yarns produced from synthetic, continuous-filament yarns which are thermoplastic. Other continuous-filament yarns, such as for example continuous-filament viscose rayon, cannot be used as they do not heat set with a memory of the extreme twist and, therefore, are not usable in the long-stretch braids of the present invention.
The present invention is not limited to any particular number of filaments in a multi-filament, continuous-filament yarn, but it is desired to use a multi-filament yarn as a mono-filament yarn, while usable, does not have quite as superior a feel as does the continuous multi-filament yarn, which is therefore the preferred modification of the invention.
It should be noted that in spite of the twist memory of the plied yarn used in the present invention, it lends itself readily to braiding on conventional machines for producing long-stretch elastic braids. One typical example is illustrated in the Semmel Patent 2,960,904, Nov. 22, i
1960, which describes typical long-stretch elastic braids and a conventional braiding procedure which is useful in the present invention. In general the present invention utilizes the same plied yarn for all of the braiding yarn. In other words, the appearance of the braid, as far as its yarns are concerned, is more like FIGURE 1 of the Semmel patent, which represented the prior art, than Semmels own invention, which used part shiny and part dull yarns for other reasons.
Brief description of the drawings FIG. 1 shows long-stretch elastic braid in the relaxed condition, and
FIG. 2 shows a cross section of the same braid along the line 22 of FIG. 1.
Description of the preferred embodiments over two yarns of the other diagonal. One set of diagonal yarns is labelled 2 and the other 3.
It is possible to have long-stretch braids in which the braiding is slightly different, for example where one diagonal passes under and over more than two of the other diagonals. The possibilities for modification are not unlimited as it is essential for the present invention that the yarns in the braiding be sufficiently interlocked to produce the soft uniform feel and good moisture absorbency.
Although the surface of the yarns are not smooth, much less shiny, as is the case with ordinary long-stretch braids using continuous-filament, synthetic yarns, the durability and wear is in no sense adversely affected even after repeated stretching to the limit. Why this should be so is not known, but in spite of the fact that the surface of each yarn does not feel slippery or hard, abrasion does not result in a shortened life for the long-stretch elastic braid. Accordingly, it is not desired to limit the present invention to any theoretical explanation of why the advantageous physical properties of soft feel and good absorbency are obtained without reduction of durability.
1. A long-stretch elastic braid comprising elastic warp threads braided with diagonal textile yarns passing over and under at least two of the opposite diagonals, each yarn being composed of at least a pair of plied yarns formed of heat set, twist crimped, thermoplastic, synthetic, continuous-filament yarn, one yarn of each pair being twist crimped clockwise and the other counterclockwise, whereby a long-stretch braided elastic braid is obtained with a soft feel and adequate moisture absorption.
2. A long-stretch elastic braid according to claim 1 in which the numbers of twists in the twist crimping of each yarn of the plied yarn is from to twists per inch.
3. A long-stretch elastic braid according to claim 2 in which the plied yarns are of multi-filament, continuousfilament nylon.
4. A long-stretch elastic braid according to claim 2 in which the elastic warp threads are of rubber.
5. A long-stretch elastic braid according to claim 1 in which the plied yarns are of multi-filament, continuousfilament nylon.
References Cited UNITED STATES PATENTS 2,841,046 7/ 1958 Runton 872 2,948,182 8/ 1960 Huppertsberg 872 2,960,904 11/1960 Semmel 872 2,992,584 7/1961 Light 872 3,166,885 1/1965 Bridgeman et al 57152 3,315,559 4/ 1967 Cohen 872 JOHN PETRAKES, Primary Examiner.
U.S. Cl. X.R.