US2796655A - Stretchable fabric and method of making same - Google Patents

Description

STRETCHABLL AND METHOD 1 OF MAKING-SAME Reinhold F. SmewegScranton, Pm, r to Grave Silk Company; Scranton, Pa., a corporation of Pennsylyania N0 ApplicnflonDe comber 31, 1954,

Serial No- 479, 3

n Claim (CL 2872) andtben thevfitament, are subjected to; setting 0981111095 at correlated temperature and timeconditions, they thereby attain the capacity of returning toward the shape existent during the setting operation, in event of later mechanical twisting or untwisting, for example. Snch'yarns can be referred to as Comprised of stretched microcrystalline polymers. When it is desired to increase thestretchability of a fabric made from multifil yarn, it has been proposed to set them in twisted form, so that the fabric is thus composed of individual. knitted courses, wefts or warps, which have curls or twists in the filaments. In knitted fabrics there is a permissive stretchability in theloops formed in the knitting, and if a monofil 0r rmrltifil Vq'rn 1's mcmimmn .1: 1 1

versely upontthe setting temperature, other conditions i being the same: torexampl'e the "dead condition may occur at 14 turn unt'wisting (36 turns residual) atteritreatment at 170 degrees E, or at 12' turns untwisting (38 turns residual) at 200 degrees F.

The behavior of a synthetic yarn is largely determined by its history. Its dispositionupon heating, above room temperaturfl, wncn witl oullcxlcmal strut, is In harm the shape 0! relative positron of e parts existent during. the last prior setting operation: and it may develop internal stresses when detained against free return or relative position. operation can only be totally dissipated by a tratment which is more rigorous than the setting itself. Fol-- example, a yam which has been twisted and set at 200 degrees F. in hot water undergoes a change of shape or relative positioning which is not completely eliminated by a later immersion in water at such temperature; and in practice some of the imposed twist will not be dissipated by treatment at 212 degrees F.

7 It hastbeen found that a yam having a pre-set behavior imposed; atr a relatively? high temperature, which is then t given a right-hand twist of 50 turns per inch and then set,

to such shape In general, the effect of a setting twist is right or left hand. When an original multifill yarn of denier (7 filaments of about 3 denier each) is pre-set for 20 minutes in steam at lbs. pressure, and then twisted 51 turns and twist-set at 200 degrees in humid air, the liveliness required removal of about 14 turns per inch: that is, more turns were removed than with a monofil of 20 denier. The product knitted satisfactorily as an essentially dead yarn. The fabric was treated in boiling water and developed liveliness in the yarn and a satisfactory stretch in the fabric.

Another example of multifil practice with 70 denier (34 filament) yarn, was to pre-set as before in steam at 25 lbs., then twist 65 turns per inch, and twist-set at 180480. The yarn was essentially dead when 24 turns were removed, and was knitted. Upon treatment with 212 degrees steam, the yarn exhibited liveliness of 33 turns per inch through set-release.

A further example with 70 denier (34 filament) multifil yarn was to pre-set as before, then twist 103 turns per inch, and twist-set at 180-180. The yarn was essentially dead when 33 turns were removed, and was knitted. Upon treatment with 212 degrees steam, the yarn exhibited liveliness of 49 turns per inch, and the fabric had a crepe effect.

The amount of original twisting desirable for a given case depends upon the size of the filament, and the purpose of use. It must be sufiicient to permit the untwisting, after setting, so that the yarn is non-lively at knitting, and to have a potential efiect available upon set-release, to produce the desired liveliness of the yarn in the fabric. With filaments below 10 denier, e. g. at l or 2 denier, the twisting effect or liveliness in the fabric yarn may obviously be correspondingly higher: while at 20 and denier, significant effects in wide gauge knit fabrics for example can be obtained with twists in the yarn of the fabric of less than 10 turns per inch, and even lower twists for greater diameters.

The removal of the liveliness from the twist-set yarn need not be accomplished upon the individual yarn. For example, two monofil or multifil yarns can be pre-set, twisted and twist-set, for example with both yarns having a left twist of 51 turns per'inch. The two ends, without mechanical untwisting to remove the liveliness, can be plied together with, say, 8 turns of right-twist for 15 denier yarn: the bifilar product is then essentially yarn thus treated will not untwist completely when left free to adjust itself, but will have stored within it a condition of potential or residual untwisting ability although this is not exhibited by physical tendency to untwist further; and since it involves a second setting, subsequent to the historical treatment which pre-sets the filament or subsequent to the preferred pre-setting for stabilizing various yarns to a condition of like prior history of heat treatment.

The treatment .of the yarn or fabric therefrom, by which such residual or potential twisting ability of the yarn is availed of for inducing liveliness therein, can be referred to as a releasing or set-releasing operation, since it causes residual'or potential stress, resulting from the original twisting of the pre-set yarn, to become effective by release of the effect of the twist-setting.

Characteristic of {this invention are the preparation of a yarn which can be knitted in essentially dead 'or nonlively condition but has within it the potential ability to attain a lively or twisting state thereafter even when present in a fabric, and the preparationof a fabric from if such yarn and the production in such fabric of the lively state of the yarn whereby the fabric contracts, and may exhibit a crepe effect, and assumes a correlated condition of stretchability.

The examples are illustrative; and the invention can obviously be practiced in many other ways in accordance with this disclosure and the scope of the claims.

I claim:

1. The method of making a stretchable fabric, which comprises pre-setting yarn of stretched microcrystallin'e polymer at an elevated temperature below the adhesive temperature of the material and without significant tension thereon whereby to fix therein a condition toward which it returns during a later less rigorous heat treatment, twisting the yarn, twist-setting the yarn under conditions less rigorous than those of the pre-setting whereby a part of the strain produced in the yarn by the twisting is relieved and another part remains active therein, removing twist from the twist-set yarn so that it attains an essentially dead and non-lively condition with a potential twist therein, preparing a fabric from the yarn while in essentially dead condition, and thereafter subjecting the fabric to an elevated temperature under conditions etfectivefor releasing a part of the potential twist whereby the said yarn in the fabric becomes lively and the fabric contracts.

2. The method of making a stretchable fabric from stretched microcrystalline polyamide fiber yarn, which comprises subjecting the yarn to pre-setting under elevated temperature conditions below the adhesion temperature of the material whereby to fix therein a condition toward which it returns during a later less rigorous heat treatment, twisting the yarn, subjecting the twisted yarn to twist-setting at an elevated temperature which is not higher than 32 degrees F. below the pre setting temperature whereby a part of the strain produced in the yarn by the twisting is relieved and another part remains active therein, removing twist from the twist-set yarn so that it attains an essentially dead and non-lively condition with a potential twist therein, preparing a fabric from the yarn while in essentially dead condition, and thereafter subjecting the fabric to an elevated temperature for releasing at least a part of the potential twist under elevated temperature conditions less rigorous than those of thepre-setting whereby the said yarn in the fabric becomes lively and the fabric contracts.

3. The method of making a stretchable fabric, which comprises pre-setting yarn of stretched microcrystalline polymer at an elevated temperature below the adhesive temperature of the material and without significant tension thereon and under humid conditions whereby to fix therein a condition toward which it returns during a later less rigorous heat treatment, twisting the yarn, heating the twisted yarn under humid conditions at a lesser temperature whereby a part of the strain produced in the yarn by the twisting is relieved and another part remains active therein, removing twist from the yarn so that it attains an essentially dead and non-lively condition with a potential twist therein, preparing a fabric from the yarn while in such essentially dead condition, and thereafter subjecting the fabric to a third heat treatment under humid conditions for releasing a part of the potential twist whereby the said yarn in the fabric becomes lively and the fabric contracts.

4. The method as in claim 3, in which the said third heating is at a temperature less than the temperature of the pre-setting treatment.

5. The method as in claim 3, in which the said third heating is at a temperature greater than the temperature of the twistetting treatment.

6. The method as in claim 3, in which the said third heating is at a temperature not greater than the temperature of the twistetting treatment.

7. The method of treating a yarn of stretched microcrystalline polymer, which comprises heating the, same *nnder humid conditions to an elevated temperature below the adhesive temperature of the material whereby to fix therein a condition toward which it returns during 'a less rigorous heat treatment, twisting the yarn, and heating the twisted yarn under humid conditions and at an elevated temperature below that of the pre-setting whereby a part of the strain produced in the yarn by the twisting is relieved and another part remains active therein, and removing twist from the twist-set yarn so that it attains an essentially dead and non-lively condition with a potential twist therein.

8. A fabric made inaccordance with claim 1, and characterized in that the yarn thereof has residual potential twist therein.

9. A yarn made in accordance with the process of claim 7, and characterized in being in essentially dead and nonlively condition and having therein a potential twist which can be activated by subjection of the yarn to heating in a humid atmosphere.

10. The method of making a stretchable fabric, which comprises pre-setting at least two yarns of stretched microcrystaliine polymer at an elevated temperature below the adhesive temperature of the material and without significant tension thereon whereby to fix in each thereof a condition toward which the yarn returns during a later less rigorous heat treatment, twisting the yarns independently in the same direction, twist-setting the yarns under conditions less rigorous than those of the pre-settings whereby a part of the twist produced strain in the respective yarn is relieved and another part remains efiective therein, plying the yarns with a plying twist in the opposite direction whereby the composite yarn attains an essentially dead and non-lively condition with a potential twist therein, preparing a fab dead condition, and elevated temperature: ing a major part of" composite yarn in the, contracts.

11. The method independently pre-se the steps thereof, s in opposite directions; said two yarns in d cessive bands of the. fabric is then subjec 12. The method tion is by knitting, in the knit goods.

References UNIT 2,290,253 Sc 2,564,245 2,641,914 Neum 2,662,558 Me 2,772,191 Bur 297,810 s f O American H" 1952, Textile B H June 25, 1957 J. w. SCHAPPEL ETAL 2,796,656 MODIFIED REGENERATEO CELLULOSE ARTICLES AND METHOD FOR MAKING THE SAME Filed Sept. 6, 1952 VISCOSE SPINNING SOLUTION ADDITIVE MIXTURE OF POLYACRYLAMIDE-FORMALDEHYDE PRECONDENSATE THICKENER SPINNING AND STRETCHING' WET PROCESSING CURE IN PRESENCE OF CROSS- LINKING CATALYST