US3158985A

US3158985A - Textile yarns and method of making the same

Info

Publication number: US3158985A
Application number: US285498A
Authority: US
Inventors: Ronald F Spicer
Original assignee: Kendall Co
Current assignee: Kendall Co
Priority date: 1963-06-04
Filing date: 1963-06-04
Publication date: 1964-12-01
Anticipated expiration: 1981-12-01
Also published as: BE648840A; DE1510695B1; NL6405997A; GB995536A; CH428516A

Description

Dec. 1, 1964 R. F. SPICER 3,158,985

TEXTILE YARNS AND METHOD OF MAKING THE SAME Filed June 4, 1963 2 Sheets-Sheet 1 Win United States Patent 3,158,985 TEXTILE YARNS AND METHDD GT MAKING THE SAME Ronald F. Spicer, Walpole, Mass, assignor to The Kendall Company, Boston, Mass, a corporation of Massachusetts Filed June 4, 1%3, Ser. No. 285,498 21 Claims. (Cl. 57-152) This invention relates to the preparation and utilization of wrapped elastic yarns. More particularly, it relates to improvements in the art of making and utilizing wrapped elastic yarns including a transient stretch-limiting member and to fabrics manufactured therefrom.

In the utilization of elastic yarns for the production of stretch fabrics and elastic fabrics, the natural elasticity of such yarns leads to difficulties in the weaving or knitting processes, since the yarn tends to stretch under the processing tensions employed. Since the frictional and mechanical tensions which develop are often of an intermittent and variable nature, it is difficult to arrive at uniformly fabricated textiles when using elastic yarns.

It has therefore been proposed to combine with an elastic core a non-elastic second core, wrapping the multiple core while the elastic member is either unstretched or stretched to any predetermined extent within its elastic limit. The inelastic core member may be of a type that may be subsequently dissolved out, or it may be a member that Will withstand the stresses of weaving but is frangible enough to rupture when extra stress is applied after the yarn has been converted into a fabric.

Such an inelastic member is designated herein as a transient strand, and potentially elastic yarns restrained by the presence of such a strand are said to be transiently stabilized.

It has also been proposed to limit the extensibility during weaving of elastic yarns by Wrapping an elastic core in the conventional manner and then overwrapping the composite yarn with a transient restraining yarn applied as a spiral outer Wrap. Various other expedients have been resorted toin efforts to find a solution to the problem of stabilizing an elastic yarn against elongation during its conversion into a fabric, but none has been entirely satisfactory. When anelastic core in an extended state and, an inelastic core are Wrapped together by a conventional spiral-wrapping technique, a tight wrap, usually of several layers, must be used, and the machine settings mustbe adjusted with critical accuracy. Otherwise, the tendency is for the elastic member of the core to contract on leaving the wrapping process, resulting not in an inelastic yarn but in an elastic yarn of limited extensibility. When it is desired to manufacture such elastic yarns under different degrees of extension, the experimentation with machine settings and wrapping tensions is burdensome. The problembecomes even more complex when nonconventionalwrappingis employed, of the type described in US. Patent 3,078,654 to P. F. Marshall and US. Patent 3,011,302 to K. J. Rupprecht.

I have found that the preparation and utilization of transiently-restrained yarns is facilitated by combining,

in a wrapping operation of a desired type, an elastic core member with -a second core member that is inelastic but retractable. By an elastic -core member I mean a strand or set of strands which readily extend to several hundred percent, with relatively rapid recovery, such as rubber yarns, spandex yarns, and the like, widely-known and usedin the garment and elastic stocking industries. By an inelastic retractable core member I mean a strand or set of strands which when suitably treated will shrink substantially in length, but which will withstand the normal stresses and tensions of weaving or knitting Without showing substantial elongation. This retractable inelastic strand must be removable from the fabric by appropriate treatment when the restraint it affords against elongation becomes undesirable.

By the use of such a combination of strands in the process of this invention, it becomes possible to weave elastic fabrics in which the elastic yarns are in an extended state when Woven, or in a normal and relaxed state, or even in a state of compression, as will appear more fully hereinbelow. That is, by proper exercise of this invention, transiently stabilized elastic yarns can be made which when woven into a fabric will cause the fabric to increase in width when the restraining strand is removed, rather than to decrease, as is normaly encountered.

It is therefore an object of this invention to provide a novel process for transiently stabilizing a potentially elastic wrapped composite yarn, and the product thereof.

A further object is to provide a process for transiently stabilizing a potentially elastic wrapped composite yarn wherein the elastic yarn element is adhesively united to the wrapping element, and the product of said process.

Still a further object is to provide a process for making a transiently stabilized potentially elastic yarn in which the elastic element is in a state of compression.

Another object is to provide methods for the preparation of elastic fabrics of novel properties.

Other objects of the invention will appear more fully in the balance of the specification and claims.

Basically, the steps involved in the process of this invention comprise: Y

(1) Passing an elastic core strand, either extended or non-extended, together with a retractable inelastic core strand into a process zone or device for applying a wrapping strand or strands.

(2) Combining the core strands by wrapping them together by the use of at least one externally applied wrapping strand.

The subsequent processing depends on whether the elastic core strand was extended or not extended when wrapped. If it were wrapped under tensioni.e. extended, then:

(3) The composite yarn is allowed to relax to a desired degree of extension, thus deforming the inelastic core strand into a waved or convoluted configuration.

(4) The convoluted retractable core strand is treated to shrink it down to a length which matches the length of the elastic strand, whereby the convoluted surplusage of the retractable strand is eliminated and said strand stabilizes the composite yarn against further elongation.

Alternatively, if the elastic core strand was combined with retractable strand while the elastic strand was under little or no extension, there is no natural elastic tendency for the composite yarn to retract, so:

(5) The composite yarn is treated so as to cause the inelastic retractable strand to retract to a desired degree, whereby the elastic yarn is deformed into a waved or convoluted configuration: that is, there is a built-in surplusage of elastic strand, parts of which may be presumed to be under longitudinal compression. Again, the composite yarn is stabilized against extension by the set condition of the retracted inelastic core strand.

(6) The yarn, stabilized by either of the above methods, is converted into a fabric structure.

(7) The stabilizing inelastic core strand is dissolved, ruptured, or otherwise rendered ineffective, whereby the elastic properties of the fabric are developed.

The invention will be more clearly understood by reference to the drawings, in which:

FIGURE 1 is a fragmentary side elevation of the assembled elements of a yarn useful in the practice of this invention, a single wrapping strand only being shown for clarity.

FIGURE 2is a representation of the composite yarn of greases FIGURE 1 after relaxation of the elastic core strand, said elastic core strand having been wrapped while extended.

FIGURE 3 is a representation of the composite yarn of FIGURE 2 after the transient core member has been caused to retract.

FIGURE 4 is the composite yarn of FIGURE 1 after shrinkage of the inelastic core strand, the elastic core strand having been wrapped under little or no extension.

FIGURE 5 is the yarn of FIGURES 3 or 4 after removal of the transient core member.

FIGURES 6 through 10 represent another embodiment of the invention wherein an elastic core member, a retractable transient core member, and an inelastic permanent stay member are combined into a composite wrapped yarn. V

FIGURES 11, 12, 13 and 14 are comparable to FIG-

URES

1, 2, 3, and 5 respectively, except that the wrapping strand is disposed around the composite yarn in a different manner.

Referring in detail to FIGURES 1 and 11, in each case an elastic core strand 1%, such as rubber or spandex, is combined with a non-elastic core strand 12 which is both retractable and which can be rendered ineffective at a subsequent stage. In FIGURE 1, the two strands are bound together by conventional helical wrapping methods, a single strand 1 10f the customary double-wrapping process being shown here. Methods for combining the two core members and the wrapping strand or strands are sufficiently Well-known in the art as to require no further explanation here.

In FIGURE 11, a similarly extended elastic core strand 1% is combined with a similar non-elastic core strand 12, except that the wrapping strand 14 is wound around the two core members in the form of double-back loops, as described in US. Patent 3,078,654.

In both FIGURES 1 and 11, the elastic strand 11 is considered to be under extension when it is combined with the inelastic retractable strand 12 in the wrapping operation.

FIGURES 2 and 12 show the essential natures of the

composite yarns

1 and 11 after the elastic core member is allowed to contract from its elongated condition during winding. The inelastic core member 12 is now corrugated or convolved into a tortuous configuration marked by bend or folds 16. In this condition, the elastic core member may readily be extended again out to the original lengths shown in FIGURES 1 and 11, with the inelastic core member 12 merely acting as a stay yarn to limit the extension of the elastic core member 10 to that elongation at which

strands

10 and 12 were originally wrapped together.

However, by its declared nature, the inelastic core member 12 is also capable of retraction, which may be effected by heat, moisture, chemical sensitivity, or other mechanisms known in the art. FIGURES 3 and 13 show the yarns of FIGURES 2 and 12, resectively, after a retracting process has been carried out on the inelastic core member 12 in both cases. The convoluted conformation of the strand 12 of FIGURES 2 and 12 has given way to a smooth configuration, the elastic and the inelastic core members are of substantially equal length, and the composite yarn is stabilized against elongation by the re tracted configuration of the strand 12.

While the composite yarns are in the stabilized conditions shown in FIGURES 3 and 13, they may be woven, knitted, or otherwise fabricated into textiles in which they form a major or a component element, said fabrication, due to the pro tein inelastic nature of the yarns, being essentially free from the difficulties referred to above as being normally inherent in the conversion of elastic yarns to fabrics.

After the fabrication of the yarns of FIGURES 3 and 13 into textile structures, the restraining effect of the core member 12 is removed by an appropriate process, as by dissolving it out, or by subjecting the textile structure to a stretching operation of a stress sufficient to rupture the core member 12 into numerous disconnected fragments, as is known in the art. FIGURES 5 and 14 represent the yarns of FIGURES 3 and 13 after the restraining strand 12 has been dissolved out, with the resultant yarn free to elongate.

FIGURE 4 represents a novel transiently stabilized elastic yarn wherein the elastic core strand 10 was under little or no tension when it was wrapped. In this case, appropriate shrinkage of the retractable strand 12 has caused the composite yarn as a whole to shrink, thus forcing the elastic strand into a compressed condition. marked by bends or folds 15. In this stabilized condi-- tion, the yarn of FIGURE 4 may be converted to a fabric. If the retractable strand 12 has been shrunk by one-third of its length, compressing the elastic strand along with it, it is possible to weave fabrics say 40 inches wide which upon removal of the transient restraining strand will tend to expand in width to 60 inches, a useful property otherwise not readily realized in the manufacture of stretch fabrics.

FIGURES 6 through 10 represent another modification of the process of this invention where it is desired to produce a wrapped elastic yarn that can be stabilized against extension in the weaving or knitting process, as above, but which will be of limited elongation after the transient restraining yarn is removed. FIGURE 6 shows an elastic core strand 10, a retractable inelastic transient strand 12, and a permanent inelastic strand 18, the function of which may best be described by calling it a stay strand. The three-member core is wrapped conventionally, only one wrapping strand 14 being shown for the sake of clarity. The elastic core strand 10 is under extension when being wrapped in FIGURE 6. When the composite yarn: is allowed to retract, as shown in FIGURE 7, both the transient retractable yarn 12 and the permanent stay yarn are buckled. Treatment of the relaxed composite; yarn to cause the retractable strand 12 to shrink leads to the yarn configuration of FIGURE 8, wherein the normal tendency of the elastic core strand 10 to elongate is pre-- vented by the matching length of the non-retracted in elastic strand 12. In this condition the yarn of FIGURE 8, like the yarns of FIGURES 3 and 11, is stabilized against elongation and may be woven or knitted into a textile fabric much as an ordinary inelastic yarn is utilized. After conversion into a fabric, the yarn of FIGURE 8 15 treated to render the transient yarn 12 ineffective, Wl'llCh may be done by rupture or dissolution of yarn 12. FIGURE 9 represents the yarn of FIGURE 7 after removal of the transient restraining yarn 12, and FIGURE 10 is the yarn of FIGURE 9 under tension. It will be appreciated that whereas the yarns of FIGURES 5 and 14 are capable of elongation up to the elastic limit of the elastic core 10, or to the point at which the wrapping strand 14 exerts a limiting influence, the yarn of FIG- URE 9 is limited in extension to the original length at which the elastic core yarn 10 and the permanent stay yarn 18 were combined together, beyond which point the relatively inelastic stay yarn 18 cannot be stretched. The practise of this modification of the invention will be found particularly advantageous in the fabrication of certain garments or elastic supporting members therefor, where in 1t is desired to realize an elastic material with lowmodulus of elongation and limited stretch. The low modulus of elongation is provided by converting theyarn into a fabric while the elastic core is under little or no extension, say at extensions of or less: the. limited stretch is provided by the stay yarn 18.

The elastic core yarn 169 in this invention is conveniently a natural or synthetic rubber yarn, or a yarn of a segmented polyurethane type known generically as a spandex yarn, one type of which is Lycra yarn made by E. I.v du Pont. The wrapping yarn may be any desired yarn which is not adversely affected by the retraction process to which the transient core strand 12 is subjected, as set.

forth more fully below. The stay strand 18 may also be of almost any desired nature: a yarn of continuous filament nylon is quite satisfactory.

The retractable transient core member obviously must meet several requirements: it must be capable of being retracted or shrunk by a non-destructive process which is not damaging to the other strands in the composite wrapped yarn structure: in the retracted state it must essentially stabilize the composite yarn against the processing tensions of a weaving or knitting operation: after the Weaving or knitting operation it must be readily removed or rendered ineffective by a process which does not damage the rest of the yarn components in the fabric.

As one type of retractable transient core strand I may use a yarn of polyvinyl alcohol filaments, generically known as vinal. I am aware that it has been proposed to use polyvinyl alcohol yarns as scaifolding yarns, due to their water solubility, much as calcium alginate yarns are used and later dissolved in alkaline solutions. However, so far as I am aware, it has not been known to carry out an intermediate retraction process on the polyvinyl alcohol yarn to diminish its length. Hitherto, polyvinyl alcohol yarns and calcium alginate yarns have been treated as equivalents in the transient yarn art, whereas in the process of this invention I find polyvinyl alcohol yarns eminently suitable and calcium alginate yarns quite unsuitable, due to the fact that the latter yarn cannot be readily retracted by any process with which I am familiar.

Preferably, the degree of retraction potential in the transient retractable yarn should be of the order of 40% or 50%, although such degrees of retraction need not always be utilized. That is, if an elastic core strand is extended 300%, to four times its original length, and is combined with a polyvinyl alcohol filament strand by a wrapping operation, a subsequent 50% retraction of the polyvinyl alcohol strand will stabilize the composite yarn at a point where the elastic core strand is extended 100%, or to twice its original length.

Retraction of a polyvinyl alcohol transient core strand may be readily efiected by the use of moisture. As in the case of most reactions involving wetting, swelling, and the release of inherent contractile strains, this is a timeatemperature dependent reaction. For example, a 420 denier spandex core strand was extended 300%, combined with a 300 denier polyvinyl alcohol core strand, and wrapped with two strands of 75 denier 30 filament viscose yarn according to the method described in U.S. Patent 3,078,654. When a length of this composite yarn was dropped into water at 20 C., retraction was quite sluggish, taking about 5 minutes for completion. At 35 C. the retraction was complete in about 30 seconds: at 50 C., retraction was practically instantaneous.

This indicates the advisability of using moisture conviently in the form of either hot water or moist steam to efiect the retracting process with optimum speed when polyvinyl alcohol is used as the retractable strand. Care must be taken, however, that the yarn is not boiled in water, since at the boil polyvinyl alcohol is readily soluble. It is convenient to expose the wrapped composite yarn, comprising elastic core strand, inelastic transient retractable strand, and wrapping strand, to the action of moist steam, or to the effect of Warm water followed-by passage over a steam-heated dry can or similar device, to effect retraction. This has an added advantage in the case that the wrapping was done while the elastic core member was under substantial elongation--that is, 200% 'or'rnorein that the effect of moisture at elevated temperatures is to gelatinize the polyvinyl alcohol transient member, without dissolving it, and by this gelatinization to render it sticky so that itfuses the wrapping strand and the elastic core strand into an inelastic composite yarn. It will be recognized bythos'e' skilled in the art that the sient core strand to water at C. or above, followed by rapid drying, will serve both to retract the yarn and render it adhesively bonded to the wrapping yarn and the core, prolonged exposure to Water at over 90 C. will gelatinize the polyvinyl alcohol strand to such an extent that it loses strength and eventually dissolves. In the practise of this aspect of the invention, the process should be conducted so that the polyvinyl alcohol strand is (1) retracted, and (2) rendered adhesive, but (3) not heated to the point of complete gelatinization, strength loss, or dissolution. In general, immersing a composite yarn of this type in water heated to 50 or 60 C., for one or two seconds, followed by drying on a revolving drum heated with low-pressure steam, will serve to stabilize the composite yarn with an accompanying fusion of the transient polyvinyl alcohol core strand with the wrapping strand and the elastomeric core strand.

As mentioned above, fusion of this type is particularly advantageous when the elastomeric core strand has a strong tendency to retract spontaneously: that is, when it has been wrapped under considerable extension, so that the elastic modulus is high. If the elastic core strand has been elongated only or to twice its unextended length in the wrapping process, and it is desired to stabilize this yarn at an elongation of 50% by retracting the transient retractable core strand, then the mere contact and presence of the retracted transient core strand may serve to stabilize the composite yarn in this low-modulus portion of the elongation curve, without the development of adhesive union between wrapping strand and elastomeric core strand.

Other transient retractable core strands include materials which retract by heat alone, without the use of water, such as Vinyon, a product of Union Carbide and Carbon Corporation. Although the normal cellulose acetate yarns of commerce are not heat-retractable, they do become so when plasticized by the inclusion of 30 parts or more of plasticizer per 100 parts of cellulose acetate. In the case of both Vinyon and plasticized acetate, a retractable transient core strand made of these materials may be both retracted and rendered adhesive under the influence of heat, the Vinyon requiring lower temperatures than the plasticized acetate.

After the yarns thus stabilized have been converted into fabrics, the stabilizing influence of the transient yarn may be rendered ineffectual by methods known in the art: that is, by exposing the fabric to stresses sufiicient to rupture the transient strand, or more satisfactorily by dissolving out the transient strand. In the case of a transient polyvinyl alcohol strand, this may readily be done by boiling thefabric in Water. Both Vinyon and plasticized acetate may be dissolved out by the use of acetone. Other mthods of practising the invention will readily occur to those skilled in the art.

A particular advantage of composite yarns stabilized by the retraction of a transient core member, in accordance with this invention, is that the stabilization may be made exact and absolute by, a simple tension adjustment in the retraction process. It should be recognized that it is difiicult to stabilize a composite elastic core-transient core assembly by conventional wrapping methods, since the retractive tendency of the elastic core tends to override the stabilizing influence of the transient core. Multiple conventional wrappings are usually necessary, andthe prior art methods completely fail to stabilize composite wrapped yarns made according to U.S. Patents 3,078,654 or 3,011,302. When 'an elastic core is elongated and combined with an inelastic transient core by a wrapping process, there is always a tendency for the composite yarn to retract to some degree after it emerges from the wrapping-operation. The final degree of elongation of such a composite yarn will be a function of the desire of the elastic core strand to retract, as opposed by the constrictive tendency of the wrapping strand to limit such contraction, and considerable experimentation and constant supervision of machine settings is necessary to produce a successful yarn.

The advantages of the process of this invention will be apparent from the following example:

A supply of yarn was prepared by combining a 420 denier spandex core strand and a 300 denier 12 filament polyvinyl alcohol core strand which were wrapped with two strands of 75 denier 30 filament viscose yarn according to the process of US. Patent 3,078,654. In the wrapping process, the spandex core strand was extended 300%, or to four times its original length. After wrapping, the composite yarn was allowed to relax completely. A ten inch length of the relaxed yarn could be readily extended to 30 inches, or 200%. It will be appreciated that this inch length of yarn represented only 7 /2 inches of original spandex core strand, extended 33% to 10 inches and held there by the nature of wrapping.

The relaxed stable yarn of this type was elongated 200% and held at that elongation while it was treated with water at 60 C. and then was immediately dried by a drum heated by low pressure steam. The resulting product was a stable inelastic yarn containing a spandex core strand stabilized at 200% elongation from its wrapped length.

The experiment was repeated using successively lower tensions so that the composite yarn was stabilized at 150%, 100%, and 50% elongations. In each case a stable inelastic yarn resulted.

Samples of each of the above yarns were boiled in Water for a brief time, with the consequent disappearance of the polyvinyl alcohol strand. The result was a wrapped elastic strand capable of elongation to over 500% of its relaxed length. As is customary with yarns containing a transient core which is removed after fabrication into a textile material, the ultimate elongation of the yarn of the above example was greater than that of a similar yarn wrapped without a transient core strand, since the space once occupied by the transient strand is now void space: the wrapping strand therefore fits more loosely around the elastomeric core strand, and exerts a less constraining effect on the yarn elongation.

Having thus described my invention, I claim:

1. A process for making a transiently-stabilized, potentially elastic composite yarn which comprises combining in essentially parallel arrangement an elastic core strand and an inelastic potentially retractable core strand,

wrapping said core strands with at least one wrapping strand,

causing one of said core strands to decrease in length,

and stabilizing said composite yarn against extension.

2. A process for making a transiently stabilized, potentially elastic wrapped composite yarn which comprises combining in essentially parallel arrangement an elastic core strand and an inelastic potentially retractable core strand,

wrapping said core strands with at least one wrapping strand,

treating the composite yarn to cause said inelastic potentially retractable core strand to retract to a length less than the length at which said strand was wrapped, and stabilizing said composite yarn against extension.

3. A process for making a novel elastic fabric which comprises combining in essentially parallel arrangement an elastic core strand and an inelastic potentially retractable core strand,

wrapping said core strands with at least one wrapping strand,

treating the composite yarn to cause said inelastic potentially retractable core strand to retract to a length less than the length at which said strand was wrapped, thus placing said elastic core strand under compression,

converting the composite yarn into a fabric,

and rendering ineffective the stabilizing restraint of said retracted inelastic strand, whereby an elastic fabric is produced which tends to expand due to the release of compression of theelastic core strand.

4. A transiently stabilized, potentially elastic wrapped composite yarn which comprises an elastic core strand under longitudinal compression,

a transient inelastic core strand,

and at least one wrapping strand serving to hold said elastic and inelastic core strands in contact.

5. A process for making a transiently stabilized, po-

tentially elastic yarn which comprises combining in essentially parallel arrangement an elastic strand under extension and a retractable inelastic strand,

wrapping the two strands with at least one wrapping strand,

allowing said elastic strand to relax to a predetermined degree of elongation,

and causing said inelastic strand to retract to a length substantially equal to the length of said relaxed elastic strand.

6. A process for making a transiently stabilized, po-

" tentially elastic wrapped yarn which comprises combining in essentially parallel arrangement an elastic strand under extension and a retractable inelastic strand capable of being rendered adhesive, wrapping the two strands with at least one wrapping strand, and treating said inelastic strand to cause it to adhere to said elastic strand and to said wrapping strand, whereby elongation of the composite yarn is inhibited. 7. A process for making a transiently stabilized potentially elastic wrapped yarn which comprises combining in essentially parallel arrangement an elastic strand under extension and a retractable inelastic strand capable of being rendered adhesive, wrapping the two strands with at least one wrapping strand, allowing said elastic strand to relax to a predetermined degree of elongation less than the degree of elongation at which the composite yarn was wrapped, causing said inelastic strand to retract to a length sub stantially equal to the length of said partially relaxed but still elongated elastic yarn, and treating said retracted inelastic strand to cause it to adhere to said elastic strand and to said Wrapping strand, whereby the composite yarn is stabilized against elongation. 8. An inelastic yarn capable of being converted into an elastic yarn which comprises an elastic core strand, a transient inelastic core strand in essentially parallel arrangement with said elastic core strand, and at least one wrapping strand serving to hold said elastic and said inelastic core strands in contact, said inelastic core strand being adhesively united to said elastic core strand and to said wrapping strand. 9. A process for making an elastic fabric which comprises combining in essentially parallel arrangement an elastic strand under extension and a retractable transient scaffold strand, wrapping the two strands with at least one wrapping strand, allowing said elastic strand to relax partially to a predetermined degree of elongation, causing said inelastic strand to retract to a length substantially equal to the length of said partially relaxed but still elongated elastic strand, converting the stabilized composite yarn into a fabric, and rendering inelfective the stabilizing restraint of 9 said retracted inelastic strand, whereby "an elastic fabric is produced.

10. A process for making anela'stic fabric which comrises p combining in essentially parallel arrangement an elastic strand under extention and a retractable transient scaffold strand capable of being rendered adhesive, wrapping the two strands with at least one wrapping strand,

allowing said elastic strand to'relax partially to a predetermined degree of elongation,

causing said inelastic strand to retract to a length substantially equal to the length of said partially relaxed but still elongated elastic strand,

treating said retracted inelastic strand to cause it to adhere to said elastic strand and to said wrapping strand, thereby stabilizing the composite yarn against elongation, converting the stabilized composite yarn into a fabric, and rendering ineffective the stabilizing restraint of -said retracted inelastic strand,

whereby an elastic fabric is produced.

11. A process for making a transiently stabilized, potentially elastic wrapped yarn which comprises combining in essentially parallel arrangement an elastic strand under extension and a polyvinyl alcohol strand capable of becoming adhesive under the influence of water,

wrapping the two strands with at least one wrapping strand, treating the extended composite yarn with water at about at least 50 C.,

and drying the wet composite yarn so as to render the polyvinyl alcohol strand adhesively united to said elastic core strand'and to said wrapping strand.

12. A process for making a transiently stabilized, potentially elastic wrapped yarn which comprises combining in essentially parallel arrangement anelastic strand under extension and apolyvinyl alcohol strand capable of retracting and becoming adhesive under the influence of water,

wrapping thetwostrands with at least one wrapping strand, allowing said elastic strand to relax partially to a predetermined degree of elongation less than the degree of elongation at which the composite yarn was wrapped,

treating the partially extended composite yarn with water at about at least 50 C., whereby said polyvinyl alcohol strand is retracted to a length substantially equal to the length of said partially elongated elastic strand,

and drying the wet composite yarn so as to render the polyvinyl alcohol strand adhesively united to said elastic core strand and to said wrapping strand. 13. A process for making a transversely-stabilized wrapped yarn of limited potential extensibility which comprises combining in essentially parallel arrangement an elastic strand under extension and two inelastic strands, one of said inelastic strands being. capable of retraction,

wrapping the three strands with at least one wrapping strand,

allowing said elastic strand to relax to a predetermined degree of elongation,

and causing said retractable inelastic strand to retract to a length substantially equal to the length of said relaxed elastic strand,

said retraction of said retractable inelastic strand not causing 'a significant shrinkage in the second inelastic strand. 14. A process for making a transiently-established wrapped yarn of limited potential extensibility which comprises combining in essentially parallel relationship an elas- 1 0 tic strand under extension and two inelastic strands, one of said inelastic strands being capable of being rendered adhesive, wrapping the three strands with at least one wrappingstrand, I

and treating the potentially adhesive strand to cause it to adhesively unite the elements of the composite yarn into an inelastic structure.

15. A process for making a transiently-stabilized wrapped yarn of limited potential extensibility which comprises combining in essentialy parallel arrangement 'an elastic strand under extension and two inelastic strands, one of said inelastic strands being capable of being retracted and of being rendered adhesive .by

conditions under which the other inelastic yarn remains unaffected,

wrapping the three strands with at least one wrapping strand,

allowing said elastic strand to relax to a predetermined degree of elongation less than the degree of elongation at which the composite yarn was wrapped,

causing the-retractable inelastic strand to retract to a length substantially equal to the length of said partially relaxed but still elongated yarn,

and treating said retracted inelastic strand to de-- velop its adhesive properties,

whereby theelements of the composite yarn are fied into an inelastic structure.

16. A wrapped inelastic yarn capable of being converted into an elastic yarn of limited extensibility which comprises an elastic core strand an inelastic core strand longer than said elastic core strand disposed in convoluted but essentially parallel relation to said elastic core strand,

a transient inelastic core strand essentially parallel to the two other core strands and of a length equal to said elastic core strand,

and at least one wrapping strand serving to hold said elastic core strand and said two inelastic core strands in contact.

17. A process for making an elastic fabric of limited extensibility which comprises combining in essentially parallel arrangement an elastic strand under extension,

a retractable transient inelastic scaffold strand,

and a second inelastic strand,

wrapping the three strands with at least one wrapping strand,

allowing said elastic strand to relax partially to a predetermined degree of elongation,

causing said retractable transient inelastic strand to uniretract to a length substantially equal to the length of said partially relaxed elastic strand,

said retraction being carried out under conditions which do not retract said second inelastic strand,

converting the stabilized composite yarn into a faband rendering ineffective the stabilizing restraint of said retracted inelastic strand,

whereby an elastic fabric is produced, the elongation of the yarns of which is limited by the presence of said second inelastic strands.

18. A process for making an elastic fabric of limited extensibility which comprises combining in essentially parallel arrangement an elastic strand under extension,

a retractable inelastic transient scafiold strand capable of being rendered adhesive,

and a second inelastic strand,

wrapping the three strands with at least one wrapping strand,

causing said retractable inelastic yarn to retract to a length substantially equal to the length of said partially relaxed elastic strand,

treating said retracted strand to cause it to become adhesively bonded to the other elements of the composite yarn,

converting the thus stabilized composite yarn into a fabric,

and rendering ineffective the stabilized restraint of said retracted inelastic strand,

19. A process for making a transiently-stabilized wrapped yarn of potentially limited extensibility which comprises combining in essentially parallel arrangement an elastic strand under extension,

21 polyvinyl alcohol strand capable of becoming adhesive under the influence of Water,

and a nylon strand,

wrapping the three strands with at least one wrapping strand,

treating the extended composite structure with water at at least about 50 C.,

and drying the Wet composite yarn so as to develop the adhesive properties of the polyvinyl alcohol strand,

whereby the elements of the composite yarn are bonded together in an inelastic configuration.

20. A process for making a transiently-stabilized wrapped yarn of potentially limited extensibility which comprises combining in essentially parallel arrangement an elastic strand under extension,

a polyvinyl alcohol strand capable of retracting and capable of becoming adhesive under the influence of water,

and a nylon strand,

wrapping the three strands with at least one wrapping strand,

allowing said elastic strand to relax partially to a predetermined degree of elongation less than the degree of elongation at which the composite yarn Was wrapped,

treating the partially extended composite yarn with water at at least about 0., whereby said polyvinyl alcohol strand is retractecl to a length substantially equal to the length of said partially elongated elastic strand,

21. A wrapped inelastic yarn capable of being converted into an elastic yarn of limited extensibility which comprises an elastic core strand,

an inelastic core strand longer than said elastic core strand disposed in convoluted but essentially parallel relation to said elastic core strand,

and at least one wrapping strand serving to hold said elastic core strand and said two inelastic core strands in contact,

said transient inelastic core strand being adhesively united to the other elements of said wrapped yarn to render said yarn inelastic.

References (Iited in the file of this patent UNITED STATES PATENTS 2,146,966 Lilley Feb. 14, 1939 2,575,753 Foster Nov. 20, 1951 2,656,585 Jackson Oct. 27, 1953 3,030,248 Runton Apr. 17, 1962 3,078,653 Marshall Feb. 26, 1963 FOREIGN PATENTS 145,068 Australia Feb. 11, 1952 1,122,205 Germany Jan. 18, 1962

Claims

1. A PROCESS FOR MAKING A TRANSIENTLY-STABILIZED, POTENTIALLY ELASTIC COMPOSITE YARN WHICH COMPRISES COMBINING IN ESSENTIALLY PARALLEL ARRANGEMENT AN ELASTIC CORE STRAND AN INELASTIC POTENTIALLY RETRACTABLE CORE STRAND, WRAPPING SAID CORE STRANDS WITH AT LEAST ONE WRAPPING STRAND, CAUSING ONE OF SAID CORE STRANDS TO DECREASE IN LENGTH, AND STABILIZING SAID COMPOSITE YARN AGAINST EXTENSION.