US3847544A - Barre reduction process - Google Patents

Abstract

A pre-dyeing method for substantially eliminating or at least greatlly reducing the potential for thermally induced barre in textured synthetic yarns or fabrics. In a preferred embodiment yarns or fabrics which are known or believed to be likely to develop thermal barre are heated briefly at a temperature essentially equal to the highest temperature reached by any portion of the yarn or group of yarns during texturing.

Description

United States Patent [1 1 Quynn [451 Nov. 12, 1974 BARRE REDUCTION PROCESS [75] Inventor: Richard G. Quynn, Greensboro,

[73] Assignee: Burlington Industries, Inc.,

Greensboro, N.C.

22 Filed: Dec.22, 1971 21 Appl. No.: 211,052

OTHER PUBLICATIONS H.U. Schmidlin. Preparation and Dyeing of Synthetic Fibers, 1963. Publ. Chapman Hall Ltd. pp. 26-27. K. Venkataraman, The Chemistry of Synthetic Dyes. Vol. 2, I952, Publ. Academic Press lnc., New York, pp. l350-5l.

Primary Examiner-Thomas J Herbert, J r. Attorney, Agent, or Firm-Cushman, Darby & Cushman [57] ABSTRACT A predyeing method for substantially eliminating or at least greatlly reducing the potential for thermally induced barre in textured synthetic yarns or fabrics. in a preferred embodiment yarns or fabrics which are known or believed to be likely to develop thermal barre are heated briefly at a temperature essentially equal to the highest temperature reached by any portion of the yarn or group of yarns during texturing.

9 Claims, N0 Drawings BACKGROUND OF THE INVENTION This invention relates broadly to the texturing of synthetic fibers and yarns, and more particularly to a process for reducing or eliminating the fabric defect known as barre, when this barre results primarily from thermal variations during false-twist texturing.

The term barre," sometimes called barriness, and an anglicized version of the French barre (stripe), has been broadly described in the art as a flaw in fabric consisting of textural or color bars in the direction of the warp or filling. In the context of this invention, the term is accorded both a narrower and a broader connotation. It is narrower in the sense that it relates only to barre of thermal origin. It is broader because, whereas the word normally refers only to fabric, it is used herein also to refer to yarns which if combined in fabrics will lead to thermal barre. Both meanings are perhaps better indicated by the words barre potential." Whatever the context, barre ultimately refers herein to the streakor band-like shade differences observed in dyed fabrics derived from textured yarns, where those yarns have been textured under non-uniform thermal conditions.

It is thus herein more specifically called thermal barre," and it can be observed clearly only after dyeing. Other forms of barre, derived, for instance, from mechanical causes such as uneven knitting or weaving tensions, and sometimes visible even before dyeing, are not improved by the process of this invention. Likewise the process does not reduce barre resulting from structural or geometrical differences.

In the past, once the potential for thermal barre had been introduced into textured yarn, there appeared to be'only two general ways to elminate it: careful match ing of yarns by the weaver or knitter, and variations in dyeing techniques, usually involving restrictions to particular dyestuffs or costly process modifications. The latter method often produces deep shades and thus fails as a remedy when light shades are desired. Even when reasonably effective, these methods have the further disadvantage that they offer no means for the texturer himself to solve the barre problem arising from his processing. Rather, they are solutions which can only be applied by his customers at a later stage.

Accordingly, the present invention is particularly concerned with barre arising from accidental or insufficiently controlled temperature and/or speed fluctua tions during the runnning of false-twist or other texturing mechines, or from combination in a fabric of yarns, from different twisting positions on false-twisting machine or from different machines, having sometimes subtly different thermal histories, sufficient to produce thermal barre.

Unless controlled in some way, barre leads to an excessive output of seconds, i.e., fabrics which can be sold only at lower prices than first-quality goods.

SUMMARY OF THE INVENTION This invention comprises a process for substantially eliminating or at least greatly reducing the potential for barre and dyeing streaks induced in thermoplastic continuous filament yarns during texturing, especially false-twist texturing, whenever the thermal history of the yarns is not uniform. The process comprises applying to a body of yarn or fabric a temperature and time of treatment sufficient to eliminate or substantially reduce existent barre potential, which temperature will preferably be near the highest temperature experienced by any part of the yarn during texturing. The inventiondepends upon the finding that thermal barre can be erased by equilibration of the thermal effects previously produced in the constituent textured yarns in a barre-prone fabric.

Accordingly, an object of the present invention is to substantially eliminate thermal barre, as defined herein, from yarns and fabrics.

Another object is to provide a method for substantially reducing or'eliminating already present texturingproduced barre potential without having to rely, as heretofore, wholly upon the skill of the knitter, weaver, and/or dyer.

DETAILED DESCRIPTION The process hereinafter described is directed toward equilibrating the effects of unequal thermal histories of textured yarns which otherwise would be barre-pronewhen combined in fabric and dyed. The process of equilibration is a function of the conditions of temperature and heating time to which the material is subjected during application of the invention, which conditions are hereinafter more precisely defined.

More specifically, the invention consists of a process for substantially eliminating thermal barre potential in undyed barre-prone textile materials made from textured synthetic yarns comprising dry heating the fabric, all of the yarn, or that portion of the yarn found by experiment to have been deficient in thermal input during texturing at a temperature and for a time sufficient to eliminate the thermal barre which otherwise, on dyeing, would result from the different thermal histories of the yarns present.

Although primarily directed to barre, the invention is also applicable to the reduction or elimination of dyeing streaks in fabrics where said streaks owe their origin to the different thermal histories of the constituent yarns during texturing. Such streaks may realistically be regarded as small-scale barre.

A barre-prone textile material, within the meaning of this invention, is a fabric, or a collection of fibers or yarns to be made into fabric, which fabric when dyed will produce thermal barre, as the latter is defined hereinbefore. A collection of fibers or yarns may comprise only a portionv of the yarns to be used in the fabric, whenever, as explained herein, it is advantageous to subject only a portion of the yarn to the heat treatment of the invention.

If the material is already in fabric form, then the process must be applied to at least that portion of the whole body of the fabric which shows proneness to barre; if the material is still in yarn form, then the process may, if desired, be applied only to that part of the yarn which shows evidence of deficient thermal treatment during texturing, whether the latter be inclusive or exclusive of heat setting. The process may be viewed as either a supplement to or a substitute for heat-setting of textured yarn or fabric, depending upon whether heat-setting has or has not already been performed.

Although the process conditions are hereinafter best defined for polyester yarns and fabrics, specifically those of polyethylene terephthalate homopolymer or copolymer, it is believed that the invention is also applicable to other thermoplastics, especially nylons, polypropylene, and cellulose triacetate, as well as to suita process for essentially equilibrating the'unequal effects of the varied thermal histories of the component textured yarns and fibers in a barre-prone undyed fabric, said varied histories being the cause of thermal barre.

The nature and scope of the invention may be more clearly expressed, particularly in those instances where the extent of the variation of the thermal history of the component yarns is known or can be reasonably surmised, as a process for heating all or at least the thermally deficient portion of the yarn or fabric to a temperature preferably at or near the highest texturingv temperature/previously experienced by any part of the textured yarn, usually in the range of about 190 to about 230C, for a period of about 0.5 to 15 minutes, preferably about 1 to 5 minutes. When the extent of the variation in thermal history is known, it may be expressed most simply as AT, the difference between the lowest and highest texturing temperatures; and the lower the value of AT, the shorter will be the time of additional heating required to overcome its barreproducing effect.

In the simplest case thermal barre exists between only two yarns, one of which has been textured at a higher temperature than the other. With numbered letters being used to designate both yarns and their texturing temperatures, if the two temperatures T, and T are known, where T is higher than T the dry heat treatment of yarn T at temperature T will have the effect of substantially reducing or eliminating barre between it and yarn T Less preferably, longer treatments at temperatures below T are also effective. The duration of such heat treatment required to eliminate barre depends on the temperature differential AT, equaling T T heating times longer than minutes being specifically excluded from the scope of this invention. The time of treatment also varies with the denier of the yarn, because of factors of heat transfer, as well as with the chemical nature of the yarn, that is whether it be polyethylene terephthalate, nylon 66, nylon 6, or another thermoplastic.

The dry heat treatment at temperature T of yarn T may be conducted separately on yarn T but it is preferably performed after the two yarns are combined in a fabric, and it may even be simultaneously or separately performed on both yarns before knitting or weaving. So long as it is within the time limits of this invention, the heat treatment appears to have essentially no effect on yarn T With filament polyester, the preferred yarn for this invention, prolonged dry heat treatment at temperatures below 230 C has, besides a barre-eliminating effect, only the general effect of reducing the overall depth of shade in subsequent dyeing.

The fact that barre potential may be eliminated by heating yarn T, equally well in either the presence or the absence of yarn T is surprising. It might logically be surmised that, since thermal barre arises from the existence of thermal variations during texturing, the thermal history effects of yarn T, could be equilibrated with those of yarn T only by heating T, by itself. One could reasonably expect yarn T to continue to change excessively if it were further heated along with yarn T The most important application of the process of this invention depends upon the surprising finding that barre potential is eliminated by heating fabrics which contain bothyarns T and T were this not true, the invention could be applied only to yarns.

If more than two yarns are treated simultaneously, e.g., yarns T T and T where temperature T T T dry heat treatment at T of yarn T, will reduce barre between it and T but not necessarily betweenit and T within the time limits of this invention. Treatment at I would reduce barre among all three yarns.

In principle, in accordance with the teaching of this invention, all thermal barre among various yarns could probably be eliminated by treatment forsufficiently long times at a temperature equal to the highest temperature reached in texturing any one of the yarns. In practice the risk of damaging the tensile or other properties by prolonged heating limits the maximum time to about 15 minutes, and even here it is preferable when possible to avoid high temperatures, over say about 220 C with polyesters. Since polyester texturing is generally carried out around 200 C, this latter restriction is not particularly significant. Neither is the time restriction a problem in practice, for the magnitude of AT, while being sufficient to produce thermal barre, is usually unlikely to be greater than 5 to 10 C.

In actual practice in most instances where barre may arise, the values of temperatures T and T are not likely to be known. The temperature records on the process are more likely to indicate that no difference (AT) had existed, since an individual texturers purpose would be to avoid temperature variations for reasons heretofore well known in the art. Should, however, the various machine positions be so monitored that a record is available on the temperature profiles of all the positions, or should the yarns being combined have come from different texturers who had deliberately textured at different temperatures, recognition of temperature T would of course be easier than here anticipated. All that one most probably may know is that a number of different yarns, all textured at the same nominal temperature but from different positions and on different texturing machines, show barre when combined in fabric and dyed. The supposed temperature at which the texturing heaters are set is of course known, and one may know from experience to expect a fluctuation of, for example, about i5 C in a particular position on the machine.

Under these latter conditions it becomes necessary to apply some simple experiments to small samples of barre-prone fabric to find the optimum conditions for subsequent treatment of the main body of the fabric, or, in other words, to discover the approximate value of T In these experiments samples are subjected to heat treatments within small units of temperature and time. When the optimum conditions for elimination of barre are found, the same conditions are applied to the large amount of fabric to reduce its barre. Determination of these experimental conditions, though more difficult than the simple application of a known T temperature, is well within the ordinary skill of the art. Among the variables to be considered are the total mass of yarn involved (total denier of yarn, or oz/yd of fabric), the geometrical structure of the fabric (single or double knit, woven, etc.), the means of carrying out the heat treatments, whether by hot air, heated rolls or cans, etc., and the degree of acceptability of barre mined experimentally for a given combination of textured yarns, that optimum will be near the unknown T for that combination.

The ultimate causes of thermal barre, apart from the fact that it clearly arises from thermal variations during texturing, are obscure and imperfectly understood.

Since it is most probable that it is not the temperature of the heat source that is controlling, but rather the temperature of the yarn itself, it is obvious that the time of exposure, i.e., the yarn speed, is a significant source of variation in the process, and thus of thermal barre. A texturing machine position running at a higher or lower speed than its fellows is as likely a place for thermal barre to arise as one running at a non-standard temperature.

Repeated tests of barre-prone combinations of yarns have shown that such yarns very often cannot be distinguished from each other onthe basis of differences in physical characteristics such as tensile strength, density, optical birefringence, or the like. While it is surmised that the differences which later appear in dyeing are of morphological origin, depending upon relatively minor surface and/or internal structural or crystalline differences induced by the texturing operation that render the yarns incompatible with one another from the standpoint of dye receptivity, it is recognized that these conclusions are only speculative.

The invention solves the problem of finding a solution to thermal barre by making yarn dyeing characteristics uniform prior to full-scale dyeing, i.e., prior to commitment of the bulk of the yarn to dyeing. Once dyed, the fabric is essentially beyond stripping and redyeing; hence the ability to anticipate and prevent barre is of great importance.

The concept of this invention is closely related to the te ed, deas?! sedate .PE Q E temperature trol during texturing and heat setting, but it is applied even after the most careful control in texturizing has failed to prevent barre. It is perhaps also related to the known process of autoclaving, but besides the fact that it is applied at a higher temperature, for much shorter times, and for a different reason than the dimensional stabilization expected of autoclaving, it may also effectively be used as a subsequent step after autoclaving.

The process is most advantageously applied to the output yarn from single-heater texturing machines. When perfectly carried out in such a manner that barre-free yarn is produced, two-heater texturing by a single texturer may eliminate the need to apply the invention. Applied, however, to those yarns or fabrics where two-heater texturing has failed to prevent thermal barre, the process of this invention effects substantial elimination of the barre. The invention thus goes beyond the stabilization role of the second heater, taking full account, as it does. of the importance of equalizing the effects of the entire thermal history of the constituent yarns in a fabric, said history being a combination of time, temperature, yarn speed, and efficiency of heater-to-yarn heat transfer. The invention goes additionally beyond two-heater texturing in being applicable to fabrics.

The process of this invention is especially applicable to the elimination of barre from false-twist-textured yarns, but it is believed also useful with yarns textured in other ways, such as stuffer-box, knife-edge, twist,

1 gear, jet, knit-deknit, and other methods of texturing, where variations in thermal history may be expected to arise.

Further process details and understanding of the invention are afforded by the following examples which r sailimit ivs- EXAM LEl Parent or feed yarns of DuPont Dacron Type 56 (polyethylene terephthalate homopolymer), 150/34,

were textured at various nominal heater temperatures. This yarn, commonly used for texturing, a regular tenacity, semi-dull filament yarn. Texturing was conducted on a single position of a Scragg Minibulk texturing machine equipped with a single 25 inch long heater, with yarn speed 235 ft/min, false-twist spindle speed 200,000 rpm, :1 percent overfeed, and theoretical (maximum) twist level about 70 tpi. Textured yarns were prepared at texturing temperatures of 170, 190, 200, 210, 220 and 230C, and not subsequently autoclaved. The yarns were then knitted sequentially into a sock or sleeve of about 2 inches diameter, each texturing temperature comprising about 1 /2 inches length of sleeve, with a small Lawson circular knitting machine. The sock was cut lengthwise into a number of strips, and these strips were then treated for 1 minute at temperatures of (one strip each) 170, 190, 200,

210, 220, and 230 C, free to shrink, in a laboratory, circulating-air oven. The six treated strips together with an untreated (control) strip were then dyed together (in the same bath) according to a method known from previous experience to emphasize barre effects: 1 percent (owf) Latyl Blue BCN, a DuPont blue disperse dyestuff, with Sg/liter of Type M-l (biphenyl) carrier, at 210 F for 10 minutes at atmospheric pressure. The visual barre effects in the dyed, untreated (control) strip were:

170 vs. 190 C: marked barre 190 vs. 200 C: very slight barre; 190 slightly deeper in shade 200 vs. 210 C: no detectable barre 210 vs. 220 C: noticeable barre 220 vs. 230 C: very marked barre 1 In spite of difficulty in judging because of the narrow strip widths and the occasional blotchy dyeing, the following observations were made on the heat-treated strips:

1. 1n the 2l0 C treated strip, the originally marked barre between and C was almost eliminated, but that between 220 and 230 remained.

4. In every case, hot-air treatment had the effect of l reducing or leaving unchanged the barre, and

n= insr 'a. inaiL- Results are herein presented in terms of visual impressions of barre, rather than in reflectance or colonmetric measurements because it is the visual barre which is objectionable and in need of reduction.

scribed, each sock being dyed separately under the same conditions. Efforts were made to ensure uniformg ity of dyeing by good sample agitation. The results of visual judgement of the degree of barre are collected in 5 Table l. The rankings were made with a cardboard mask which blocked out all but the pair under consideration, since it was noticed that the eye is influenced by the sight of the other pairs.

EXAMPLE 2 A larger supply of textured yarns was prepared from the same parent yarn and under the same texturin conditions as described in Example I. This time the various textured, unautoclaved yarns were knitted sequentially into socks, and one entire sock each heattreated free to shrink for one minute at the various temperatures. Dyeing was conducted as previously dewono l l l l l msofrosm am moangompwv; Son. 2 2

pee 3 3 2 e2 2 3 2 @3 2 E i $8 3 2 omm I am /I 08H m so 3262 303 33 5 323 fififi m z 1533 3 3 2 e fi z 3%: U E: com I o8 I I finfi fi e fifi p w fifi fi SS BB fi fi fi e 233 33 M333 p z p E p z p z z bz 3w I 8m o nmpompou o nmpompoul oanwpompou o ngoopow o pwpoopou afififi m I 82 $2 p z 32 $2 3 3 2 com I 8H a o: onpqoo 59G 83.5 @203 woosumn 0 28 um hm 32 3 25 6 m p w wfi pm w w m fip fip z v 9.03 I 00 am I homo D08 D08 B3 9.05 3 3 3 pm t s I. a 5m .QHE n .Hom mopmmaa pmmm ham uopmompco I mn mm chow H Emu;

The results of Table l are clearly consistent with those of Example 1, and illustrate (dotted lines of Table 1) that in order to eliminate or reduce, as far as possible, barre between any given pair, one should preferably dry-heat-treat the pair at a temperature corresponding to the higher characteristic temperature of the pair. Table 1 shows in several places that treatment at a temperature which is somewhat lower than this opeimum has the effect of reducing, but not eliminating, the barre. 1f the treatment is conducted at a temperature substantially higher than that necessary for a given pair, one runs the risk of increasing the barre be tween lower-temperature pairs (although not increasing it beyond that of unheat-treated pairs). Thus, treatment of the 170/ 190 C pair at 220 C, for example,

results in barre which is worse than that resulting from either 170 C or 190 C treatment, but still better than that in the unheat-treated pair.

However, this risk is quite small in the majority of practical cases. The AT of C or C being dis"- cussed is very large by practical production standards and it would be much more likely to have a knitted or woven fabric containing yarns which had been subjected during texturing to a temperature range of perhaps 5C or les sl l'fiti's riwenrdee mostunusuar to'have' a fabric containing, for example, a majority of yarns textured at 200 C, a few yarns textured at 170 C, and a few more textured at 230 C.

EXAMPLE 3 This example illustrates the effects of a very high treatment temperature, one approaching the melting point of the fiber (about 258 C, in the case of polyethylene terephthalate). Two sequentially-knitted socks of the type described in Example 2 were hot-air treated at 250 C for 1 minute and 5 minutes. As expected, severe shrinkage of the yarns occurred, but the barre (after dyeing) was eliminated for all pairs, as far as could be judged visually.

EXAMPLE 4 This example illustrates the effects of prolonged dry heat-treatment times. Socks of the type described in Example 2 were dry-heat-treated at 200 C for 2, 5, and 15 minutes. The 2-minute treatment had the same effect (as far as could be judged visually) as in Example 2, i.e., elimination of the 200/ 190 C barre. The 5- minute treatment additionally reduced the originally very marked 190/l70 barre, and the 15-minute treatment additionally reduced very much the originally marked 220/210 barre (the'original 210/200 barre not being detectable in any case). This last result, involving a treatment time much longer than would be necessary in most practical cases, indicated that dryheat treatment for prolonged times at a given temperature could reduce barre between texturing temperature pairs higher than the treatment temperature.

EXAMPLE 5 skeinfqrm s appose to th ab afo m of hsnthsL 10 examples. The results were more difficult to judge be cause of knitting difficulties stemming from tangling of the yarn, but were similar to previous experience at 200 C for 15 minutes (Example 4) except that the 220/210 barre removal was not observed.

EXAMPLE 6 the two-heater type, i.e., one in which a second heater is placed after the false-twist spindle, so that the yarn passes successively over a primary heater, through the false-twist spindle, and then over a secondary heater before being wound onto a takeup package.

In this case the parent or feed polyester yarn, of the same type as in Example 1, was textured on a single position of an ARCT FT F double-heater machine, at a yarn speed of 235 ft/min, spindle speed of 186,500 rpm, +1 percent overfeed, for a theoretical (maximum) twist level of about 60 tpi. This machine had two heaters, each 22 in. long. The primary/secondary temperatures were 180/ 170, 210/200, and 240/230 C. The lbarre shown by knitted and dyed socks containing un- ;treated yarns was similar to that which resulted from a single heater at the same corresponding primary temperature, i.e., similar to that of the control sock of EX- :AMPLES l and 2. Dry-heat-treating, conducted as in EXAMPLE 7 This example demonstrates the application of the invention to a'barre-prone fabric where the texturing temperatures of the component yarns were unknown. Experimental textured yarns were requested where it was specified only that they be textured within the normal heater range of l220 C, that the difference not be greater than 10 C, and that the texturing temperatures be withheld. The feed yarn was DuPont Type 56, /34 polyester yarn, textured on one position of a Leesona 555 machine equipped with single heaters 40 inches long. The yarn speed was 346 ft/min, falsetwist spindle speed 270,000 rpm, +2 percent overfeed, for a theoretical (maximum) twist level of about 65 tpi. The unautoclaved yarns produced at the two unrevealed temperatures were then knitted into eight identical socks, as in previous examples, in the following sequence: about 1 1% inches sock length of yarn A, as inch of yarn B, 1 k inches of yarn A. Thus a small portion of yarn B was placed with the larger portions of yarn A on either side. After one of the socks was dyed according to the barre procedure of Example 1, the narrow strip of yarn B was distinguishable from the adjoining area in having a slightly deeper (blue) shade; i.e., it exhibited barre with respect to its neighbors. The other seven socks were separately heated in the circulating air oven for 1 minute at 5 C intervals from C to 220 C, and then dyed as before. Barre was clearly evident at all temperatures except 205C and 210 C, being still faintly visible at 205 C. it was judged from the results that 210 C was the optimum temperature for treatment. it was subsequently learned that yarn A hadbss ltex yrssl 207? 9.3m! ram .1 t 2 C If the material is already in fabric form having been woven or knitted from the previously made and textured synthetic yarn, a testing process similar to those previously described is used to determine the optimum treatment temperature and additionally utilizes wellknown sampling techniques to determine portions of the fabric that contain yarns representative of the yarn from various sources used in the fabric which yarns may have had non-uniform thermal histories. All fabric swatches removed from these previously determined portions are then individually tested in a manner similar to that used with respect to the knitted socks in the above examples to determine the optimum treatment temperature and time for each of the swatches and in addition the entire piece of fabric. Thereafter the fabric is heated at the optimum temperature and for a time period as indicated by the above tests. It is understood that many test variations either in sampling techniques, swatch testing or methods of comparing treated and untreated samples can be used without departing from the scope of this invention.

It must be emphasized that an essential element of the invention is that the elimination or reduction of texturing-induced barre requires not simply an unspecified heat treatment of the textured yarn, but a treatment the conditions of which (particularly temperature) are correlated with the previous texturing conditions. If the conditions of this barre eliminating treatment are chosen without regard to the previous texturing conditions, the resulting barre may be made worse rather than better. Table I of Example 2 shows an example where dry-heat treating at four temperatures caused increases of barre over that of the 220lgg0igcontrol.

Although the present invention is described herein with particular reference to specific details, it is not intended that such details shall be regarded as limitations u on the scope of the invention except insofar as inthetic yarns which have different dyeing characteristics caused by thermal variation in the texturin of the yarns, said process comprising dry heating said yarns, after texturing by a process from the group consisting of falssrtwist.astufisebqxzlaite-s5% t gear, jet,

and knit-deknit and before dyeing, at a temperature about equal to the highest temperature used in texturing the yarns, said dry heating being continued for a time period of from about 0.5 minutes to about 15 minutes until the effects of thermal variation in texturing have been equilibrated and only thereafter dyeing said yarns.

2. A process according to claim 1 wherein the textured synthetic yarns are continuous filament thermoplastics.

3. A process according to claim 1 wherein said yarns are polyester yarns.

4. A process according to claim 1 wherein said yarns are nylon yarns.

5. A process according to claim 1 comprising the steps of determining portions of said fabric which contain yarns that are representative of the yarns used in the production of said fabric; removing at least one fabl'lC sample from at least one of said representative por-.

tions; dyeing at least a Eortion of each of said fabric samples to emphasize t e barre effect occurring between said yarns in each fabric sample; dividing said undyed Eortion of each of said fabric sample into strips and dry eat treating each of said strips for constant periods of time and at different temperatures; dyeing said strips in a manner similar to the way in which the previously dyed portion was dyed; comparing the previously dyed portion of each fabric sample with said strips divided out of the previously undyed portion of the same fabric sample after said strips have been heat treated and dyed; determining the amount of heat input, as a function of time and temperature, required to eliminate any barre effect existing between said yarns due to thermal variation in previous texturing of said yarns; treating said textile material at said determined amount of heat input so that the effects of said thermal variation are equilibrated in substantially all yarns within said textile material and dyeing said textile material.

6. A process according to claim 5 wherein said differnt temperatures are within the range of to 250 7. A process according to claim 5 wherein said different temperatures are within the range of to 230 UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No. 3-,8h7,5 l 4 Dated November 12, 197

Inventor(s) Richard G. Quynn It is certified that error appears in the above-identified patent and that said Letters Patent are hereby corrected as shown below:

l'l'HE SZECIFICATION:

Column 1, line 35, delete "elminate" and insert in lieu thereof --eliminate--.

Column 1, line 50, delete "meehines" and insert in lieu thereof --machines--.

Column t, line 11, delete "I and insert in lieu thereof Signed and sealed this 27th day of May 1975.

(SEAL) Attest:

C MARSHALL DANN RUTH C. MASON Commissioner of Patents Attesting Officer and Trademarks FORM POJOSO (IO-69)

Claims (9)

1. A PROCESS FOR SUBSTANTIALLY REDUCING OR ELIMINATING THERMAL BARRE IN A DYED FABRIC COMPRISING TEXTURED SYNTHETIC YARNS WHICH HAVE DIFFERENT DYEING CHARACTERISTICS CAUSED BY THERMAL VARIATION IN THE TEXTURING OF THE YARNS, SAID PROCESS COMPRISING DRY HEATING SAID YARNS, AFTER TEXTURING BY A PROCESS FROM THE GROUP CONSISTING OF FALSE-TWIST, STUFFER-BOX, KNIFE-EDGE, TWIST, GEAR, JET AMD KNIT-DEKNIT AND BEFORE DYEING, AT A TEMPERATURE ABOUT EQUAL TO THE HIGHEST TEMPERATURE USED IN TEXTURING THE YARNS, SAID DRY HEATING BEING CONTINUED FOR A TIME PERIOD OF FROM ABOUT 0.5 MINUTES TO ABOUT 15 MINUTES UNTIL THE EFFECTS OF THERMAL VARIATION IN TEXTURING HAVE BEEN EQUILIBRATED AND ONLY THEREAFTER DYEING SAID YARNS.

2. A process according to claim 1 wherein the textured synthetic yarns are continuous filament thermoplastics.

3. A process according to claim 1 wherein said yarns are polyester yarns.

4. A process according to claim 1 wherein said yarns are nylon yarns.

5. A process according to claim 1 comprising the steps of determining portions of said fabric which contain yarns that are representative of the yarns used in the production of said fabric; removing at least one fabric sample from at least one of said representative portions; dyeing at least a portion of each of said fabric samples to emphasize the barre effect occurring between said yarns in each fabric sample; dividing said undyed portion of each of said fabric sample into strips and dry heat treating each of said strips for constant periods of time and at different temperatures; dyeing said strips in a manner similar to the way in which the previously dyed portion was dyed; comparing the previously dyed portion of each fabric sample with said strips divided out of the previously undyed portion of the same fabric sample after said strips have been heat treated and dyed; determining the amount of heat input, as a function of time and temperature, required to eliminate any barre effect existing between said yarns due to thermal variation in previous texturing of said yarns; treating said textile material at said determined amount of heat input so that the effects of said thermal variation are equilibrated in substantially all yarns within said textile material and dyeing said textile material.

6. A process according to claim 5 wherein said different temperatures are within the range of 170* to 250* C.

7. A process according to claim 5 wherein said different temperatures are within the range of 190* to 230* C.

8. A process according to claim 7 wherein the heat treatment is a dry-heat treatment for a period of about 1 minute to about 5 minutes.

9. A process according to claim 5 whereiN said textured yarns contain a combination of at least two different fiber forming materials.