US2890568A - Production of voluminous yarn - Google Patents

Description

June 1959 R. A. A. wlLLENs ,890,568

PRODUQTION OF VOLUMINOUS YARN Filed June 4, 1957 I? F I6. I I

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United States Patent PRODUCTION or VOLUMINOUS YARN Robert Alfred Archibald Willens, London, England, assignor to British Celanese Limited, a company incorporated of Great Britain Application June 4, 1957; Serial No. 663,527

Claims priority, application Great Britain June 19, 1956 7 Claims. (Cl. 57-157) immediately before it enters said zone, setting in the I fibers of the yarn the distortion imposed by the falsetwist, withdrawing the yarn from said zone and collecting it an a linear speed less than that at which it was fed into said zone. In this way, it has been found that the natural tendency of the yarn to contract after being stretched can be made use of to impose a moderate and controllable degree of tension on the yarn while it possesses twist and while the distortions imparted by said twist are being set, whereby the setting is rendered more effective and more permanent. It is necessary that the relative speeds of withdrawal from the source of supply and feeding into the false-twisting zone should impose on the yarn a degree of stretch in excess of its elastic limit, i.e. the degree at which the stretch imparted is wholly and immediately recoverable on releasing the strain. By exceeding this elastic limit, some degree of delayed recovery is able to take place in the zone in which false-twisting and setting are effected. However, as the elastic limit (in the sense defined above) of nearly all textile yarns, even including wholly synthetic yarns, is very low, a moderate degree of stretch of 3 to 4% or even less is suflicient to produce a desirable effect. It is preferred, however, to use a higher degree of stretch of the order of 5 to 7 /2%, or even more provided that a degree of stretch so high as to damage the filaments is avoided. Indeed, where the yarn is of a wholly synthetic material of a kind whose tensile strength and other textile properties can be developed or enhanced by hotor cold-drawing, the hotor cold-drawing operation can be employed as the stretching operation immediately preceding false-twisting and setting. For this purpose the yarn may be given a degree of drawing of the order of 3 to 5 or even more times, according to the nature of the material. The stretching of the yarn, whether by way of hotor cold-drawing or to a more moderate degree may be facilitated, and the liability to filament damage reduced, by the application of heat or other softening agent to the yarn, though this is not generally necessary if the degree of stretch does not exceed 7 /2%. The degree of softening thereby effected, however, should not be such as to relax the yarn entirely so that the stretch takes place under very low or negligible strain whereby no substantial degree of stretch is recoverable in the falsetwisting and setting zone.

The actual control of the degree of tension existing in the false-twisting and setting zone can be best con:

trolled, in practice, by positively controlling the linear speed of withdrawal of the yarn from said zone, and collecting the yarn so withdrawn at a linear speed lower than that at which it is so withdrawn. Thus, withdrawal can be effected by means of draw-rollers or nip rollers running at a speed controlled (e.g. by means of an infinitely variable gear) in relation to that of stretching rollers by which the yarn is fed into the zone, the rollers forwarding the yarn to a take-up device driven at a lower collecting speed. The speed of withdrawal should preferably not exceed that at which the yarn is fed into the zone since this would impose a tension beyond that made available by the delayed recovery of the yarn after stretching. Where a moderate degree of contraction or relaxation is to be allowed between the stretching rollers and the take-up, e.g. of the order of 3 to 4%, the take-up device may itself be used to determine the rate of withdrawal, without the interposition of drawor nip-rollers for this purpose.

The false-twisting of the yarn can be effected by passing the yarn, before or after it passes through the setting zone, through a false-twisting spindle, conveniently of the type in which the yarn passes through a hollow and rapidly rotating spindle provided with means for guiding the yarn through several sharp changes of direction. Alternatively or in addition, however, by treating two or more yarns associated together and separating them from one another after they leave the setting zone, the false-twist to which the yarns are subjected may be imposed wholly or in part by reason of a number of turns of doubling twist as between the yarns trapped in the path of the yarns before the point of separation. In this case, it may be necessary to limit the speed at which the materials are treated to avoid filament damage at the point of separation. The maximum speed will depend on the denier of the yarn and may range, for example, from 4 metres per minute for a total yarn denier of 30, up to 10 metres per minute for a denier of 150.

Setting of the twist can be effected by any convenient means, e.g. by passing the yarn through a chamber containing wet steam at a temperature appropriate to the nature of the yarn, or by passing it through a chamber heated electrically or otherwise, or by passing it in contact with a heated surface. The setting agency will generally have the effect of moderating the degree of tension to which the yarn is subjected by the stretchrecovery of the yarn.

The invention is applicable to yarns generally, including staple fibre yarns, but is particularly applicable to continuous filament yarns, e.g. of reconstituted cellulose as in viscose yarns, of cellulose acetate or other organic derivative of cellulose and of wholly synthetic materials such as polyhexamethylene adipamide, polyaminocaproic acid, polyaminotriazoles, and polyethylene terephthalate.

By way of example some methods of carrying out the invention will now be described in greater detail with reference to the accompanying drawings in which:

Figure l is a diagrammatic side elevation showing the layout of one form of apparatus suitable for carrying out the invention;

Figures 2 and 3 show modifications of the layout of Figure 1; and

Figure 4 shows a similar side elevation of another form of apparatus for carrying out the invention.

In Figure 1, a continuous filament yarn 5 is drawn over-end from a supply package 6, through a guide 7,

and thence to a pair of rollers 8, 9 round which it passes several times and from which it is forwarded to a second and similar pair of rollers 11, 12. The'roller I slightly skewed with reference to the rollers 8, 11 and serve to lift the yarn from the surface of the rollers 8, 11 at each turn, enabling the several turns to accommodate themselves along the length of the rollers.

From the roller 11 the yarn proceeds upwards and diametrically through a steam header 13 of 2" diameter having a vertical offset tube 14 2 /2" long extending from its upper side. The offset tube 14' is provided with a yarn exit nipple 15 of smaller diameter, while the steam header 13 is provided with an entry nipple 16 directly beneath the offset tube. a distance of about 3 therefrom, the yarn passes through false-twisting spindle 17 driven at about 15,000 r.p.rn., and thence upwards through a guide 18 vertical above the spindle 17. The yarn then passes horizontally through a pair of nip rollers 19 which are rotated with a surface speed equal to or slightly below that of the stretching roller 11, and which supply the yarn to a traverse guide 21 of a winding device by which it is guided to and traversed along the length of a package 22, driven at a constant surface speed lower than that of the nip rollers 19 by means of a package-driving roller 23.

In the modification shown in Figure 2, the yarn 5 V leaving the supply roller 8 passes in contact with a heated surface 25 on its way to the stretching roller 11, and

round a snubbing pin 26, which maybe positively ro- Y tated with a surface speed less than that of the roller 8. By these means the stretching of the yarn is facilitated by the softening action of the heated surface 25, and a substantial degree of stretch of the order of 3 to 5 times or more can be effected. If it is desired to use the heated surface to facilitate a lower degree of stretch, say to 20%, the snubbing pin 26 may be omitted, or the yarn caused to pass out of contact with it.

In the modification of the apparatus of Figure 1 shown in Figure 3, the nip rollers are omitted and the yarn 5, after leaving the guide 18, passes directly to the take-up device by which it is collected at a linear speed lower than that of the stretching roller 11. This form of apparatus is suitable for use where a relatively small 7 reduction in speed as between the stretching roller 11 and the take-up package 22 is desired, e.g. of the order of 3 to 4%. suitable for a somewhat higher degree of relaxtion up to 10% or more, when the relaxation, or most of it, takes place between the nip rollers 19' and the package 22, and undue slackening and snarling of the yarn between the spindle 17 and the package is avoided.

In the layout of apparatus shown in Figure 4, two yarns 28 are drawn from separate supply packages 29 by way of guides 30, and are passed together round the supply rollers 8, 9 and the stretching rollers 11, 12. The yarns then pass one on each side of a waisted guide roller 31 beyond which they are temporarily twistedtogether. They pass together up an electrically heated tube 32 and thence through the false-twisting spindle 17, guide 18 and nip. rollers 19. On leaving the nip rollers 19-the yarns 28 pass one on each side of a second waistedguide roller 33 and are separately taken up on surface-driven collecting packages 34 driven by contact with driving rollers 35. At the beginning of the operation, the two yarns are twisted together beyond the guide 31 but before being passed one on each side of the separating guide 33. The elfect of the rotation of the false-twisting spindle is to concentrate this twist mainly below the false-twisting spindle, in the setting zone of said tube 32. The lower degree of twist (if any) between the yarns as the approach. the separating roller 33, is easily held back by that roller without undue strain on the yarns as they are separated.

Above the offset tube and at The arrangement of Fig. 1, however, is more 4 The following are given as examples of the way in which the invention is carried out:

Example I 5 Continuous filament yarn of polyhexamethylene adipamide formed of 23 filaments each of 3 filament denier is drawn from the supply package 6 of Figure 1 by the 1 roller 8. The roller 8 is driven with a surface speed of 5 metres per minute, and the roller 11 at 5.5 metres per 10 minute. The nip rollers 19 are rotated with a surface speed which may be varied from 5.3 to 5.5 metres per minute, and the package 22 is driven with a constant surface speed of 4.6 to 5 metres per minute.

Example II A cellulose acetate yarn of 100 denier is treated as in Example I, the supply roller 8 being driven at 8 metres per minute, the stretching roller 11 at 8.5 metres per minute, the withdrawing rolls at 8.3 to 8.5 metres per minute and the take-up package at 7.5 to 8 metres per minute.

Example Ill A continuous filament yarn of polyhexamethyle'nc adipamide'formed of 23 undrawn filaments each of 12.

filament denier is drawn, as in Figure 2, from the supply package 6 by the supply roller 8, which is driven at a speed of 1.25 metres per minute. The yarn then passes "in contact with the heated surface 25 and round the snubbing pin 26, and is forwarded by the stretching roller 11 at a speed of 5.5 metres per minute, after which it is treated as in Example I.

Example IV A cellulose acetate yarn of 100 denier, as in Example 35 II, is drawn from a supply package at 8 metres per minute and forwarded into the false-twist zone at 8.5 metres per minute, but is passed from the guide 18 directly to the package 22, as in Figure 3, the package being driven at a surface speed of 8.2 metres per minute. This allows a contraction between the stretching roller 11 and the package 22' of the order of 3%. a degree of relaxation which is insufficient to give rise to difficulties of snarling or excessive ballooning in the yarn as it leaves the spindle '17.

Example V Two 30 denier yarns of polyaminocaproic acid each consisting of 6 continuous filaments are drawn from the two supply packages 29 of Figure 2, the supply roller 8 being driven at 5 metres per minute and the stretching roller 11 at 5.5 metres per minute. The nip rollers 19 are driven with a peripheral speed of 4 metres per minute and the collecting packages 34 at a speed of 3.75 metres per minutes. At the beginning of the false-twisting operation the two yarns are twisted together before being passed one on each side of the separating guide 33 so that the algebraic sum of the doubling twist as between the yarns, locked between the two waisted rollers 31, 33, is 1,800 turns.

Having described my invention, what I desire to' secure by Letters Patent is:

l. A method of producing a voluminous yarn, said method comprising drawing a yarn from a source of supply at one linear speed, forwarding the yarn at a higher linear speed to a zone in which false-twist is imparted to said yarn, so as to stretch said yarn immediately before it enters said zone, setting in the fibres of the yarn the distortion imposed by said false-twist, withdrawing the yarn from said zone and collecting it at a linear speed less than that at which it was fed into said zone.

2. Method according to claim 1, comprising positively withdrawing the yarn from the zone at a speed not greater than that at which it was fed into said zone, and collecting it at a linear speed lower than that at which it is so withdrawn.

3'. Method according to claim 1, comprising stretching the yarn, without softening it, by up to 7.5% of its yarn initially associated without doubling twist, associatoriginal length. ing them with doubling twist in the false-twisting zone, 4. Method according to claim 1, comprising softening and passing them on different sides of a separating guide the yarn being stretched so as to facilitate stretching. after they leave said zone so as to trap said doubling 5. Method according to claim 4, wherein the yarn is 5 twist in Said Zone- Softened by the apphcatlon of heat References Cited in the file of this patent 6. Method according to claim 1, wherein the falsetwist is imparted to the yarn by passing it in engagement UNITED STATES PATENTS with a rapidly rotated false-twisting spindle. 2,43 2,355 Truitt Dec. 9, 1947 7. Method according to claim 1, wherein false-twist 10 2,761,272 Vandamme Sept. 4, 1956 is imparted to the yarn by using a plurality of ends of 2,810,281 Appleton Oct. 22, 1957 Notice of Adverse Decision in Interference No. 91,290 involving Patent No. 2,890,568, R. A. A. ON OF VOLUMINOUS YARN, final judgment ad- In Interference lered June 17, 1963, as to claim 1.

.Villens, PRODUCT I verse to the patentee was renc [Oflicial Gazette J My 20, 1965.]

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