US3417446A - Method and apparatus of gear crimp - Google Patents

Description

1963 R. J. FAIRCLOUGH ETAL METHOD AND APPARATUS OF GEAR CRIME" Filed NOV. 16. 196.6 I

2 Sheets-Sheet 1 1968 R. J. FAIRCLOUGH ET AL 3,417,446

METHOD AND APPARATUS 0F GEAR CRIMP I Filed Nov. 16, 1966 2 Sheets-Sheet 2 Fig.3.

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, if r Mme-"V5 United States Patent 3,417,446 METHOD AND APPARATUS 0F GEAR CRIMP Rodney James Fairclough and Peter Bernard Checkland, Harrogate, England, assignors to Imperial Chemical Industries Limited, London, England, a corporation of Great Britain Filed Nov. 16, 1966, Ser. No. 594,918 Claims priority, application Great Britain, Nov. 16, 1965, 48,629/ 65 9 Claims. (Cl. 281) ABSTRACT OF THE DISCLOSURE Polyester yarn is produced by melt spinning and drawing between feed and draw rolls, the yarn being passed between rotating intermeshing gears and across a narrow heated surface before reaching the draw roll. The yarn is subsequently bulked by relaxing and scouring.

This invention relates to the production of a modified continuous filament polyester yarn and to fabrics made from such yarn.

In British patent specification No. 808,213 a process is described for making a yarn of potentially crimped continuous thermoplastic synthetic linear polymer filaments by heating the continuous filaments nonuniformly by passing them over a narrow surface heated to a temperature above 270 C. and above the melting temperature of the filaments in such a way that the filaments are heated on one side only continuously along their length while under a tension to give a stable stretch to the filaments of not more than 10%. This tension only needs to be adequate to keep the yarn in contact with the narrow heated surface. In British patent specification No. 1,028,979 a similar process is disclosed by which improved regularity of treatment is obtained by providing such a narrow heated surface on a body of appreciable thermal capacity whereby fluctuations in the temperature of the heated surface are minimised.

Our copending British application No. 46,583/ 64 discloses a similar process operating with the temperature of the narrow heated surface above 170 C.

British patent specification No. 984,922 relates to a process for drawing and crimping synthetic polymer filaments in which undrawn filaments are heated and pulled under tension to pass once only between means causing the filaments to follow a sharply zig-zag path, the tension so imparted being such that the filaments are oriented and caused to adopt a permanent corrugated crimp, said means having a component of motion in the mean direction of travel of the filaments at the points of contact with them. The means causing the filaments to follow a zig-zag path may be intermeshing teeth or gear wheels which are rotated at a speed such that the filament speed of passage between them is less than the surface speed of the draw rolls that follow.

Such processes are particularly effective with polyester yarns and we now provide a process for producing a modified continuous 'filament polyester yarn by melt spinning and drawing between a heated feed roll and a draw roll rotating faster than said feed roll wherein the yarn, after passing the fed roll but before the draw roll passes between rotating intermeshing gears and also across a narrow surface heated to a temperature of at least 170 C.

Th narrow surface is arranged in the yarn path so that the tension of the yarn holds it in contact with the narrow surface, but the angle of deflection of the yarn path over the strip is kept sufiiciently small to obviate mechaniice cal deformation of the filaments, such as occurs in the so-called edge-crimping processes. The narrow surface is preferably heated to a temperature above the melting temperature of the polyster. The yarn may pass through the intermeshing gears before it passes across the heated narrow-surface or across the heated narrow surface before it passes through the intermeshing gears.

The yarn may be wound up or may be further subjected to a relaxation treatment by heating under a reduced tension at a temperature above the second order transition temperature of the polyester and below the melting temperature of the polyester.

The resulting bulk of the yarn depends inter alia on the extent to which the tension is reduced in the relaxation treatment, the nearer to zero tension, the greater the bulk achieved.

The relaxation treatment may be carried out by overfeeding the yarn into a heating chamber before winding up. One form of such a heating chamber comprises a tube in which a current of heated air is circulated.

The full crimp potential of the yarn is not developed by the relaxation treatment, and the crimp may be further developed by subjecting the yarn for at least one minute to a scouring treatment in a boiling aqueous medium, and it may be preferred to carry out the said scouring treatment after the yarn is knitted or woven into a fabric. The term scouring treatment here is taken also to include treatment of the yarn or fabric in a dyebath. Surprisingly, an examination of the yarn does not show a simple addition of helical crimp, derived from asymmetrical shrinkage properties, and planar sinusodial crimp, as might be expected to derive from the mechanical crimp between the gear wheels; the yarn geometry is more complicated and helical crimp can be seen in a greater amount that is usually produced from hot surface crimping as described above, but no sinusoidal crimp can be seen.

The specific volume of the yarns which may be obtained by our process is very high and may be from 1.5 to 2.5 cc. per gram. The specific volumes were measured using a grooved wheel or spool having an external diame ter of 9.3 cm., a core diameter of 2.4 cm. and a spacing of 1.244 mm. between flanges, giving a winding space having a volume of 7.89 cc. The wheel was placed in apparatus which enabled it to be driven positively at a constant spindle speed of 600 r.p.m. and the apparatus adjusted so that the initial tension on the yarn fed to the wheel was 0.0933 gm. per denier. During operation the tension increased somewhat, the extent of this being dependent on the denier of the yarn under test. When the groove was full a limit mirco-switch stopped the wheel and the yarn filling the groove was then removed and weighed. A simple calculation gave the specific volume of the yarn under test.

Further according to the present invention apparatus for the production of modified continuous filament yarn from melt-spun synthetic filaments comprises a heatable feed roll and a draw roll arranged and adapted so that in operation the draw roll is rotated faster than the feed roll, and, interposed in the filament path between the said feed roll and the said draw roll rotatable, intermeshing gear-wheels adapted in operation, to rotate at a speed greater than that of the feed roll but not greater than that of the draw roll and a heatable narrow surface arranged across said filament path.

The gear wheels are preferably rotated in operation at a speed which is less than that of the draw roll and may be placed either before or after the heatable narrow strip in filament path from the feed roll to the draw roll.

In operation the heatable narrow strip is maintained at a temperature of at least C., and preferably at a 3 temperature above the melting temperature of the filaments. It is preferably provided on a body having an appreciable thermal capacity whereby fluctuations in the temperature of the strip are minimised.

The apparatus may further comprise a relaxation cham- Example 1 Samples of 360 denier polyethylene terephthalate yarn having 36 filaments were melt spun, treated with a wet lubricating finish, and wound onto bobbins at a birefringence of 8.0x before being drawn between a feed roll heated to a temperature of 92 C. and a draw roll, the rolls being respectively rotated at speeds to give a draw ratio of 3.22:1 and a draw speed of 885 ft./min. The yarn passing from the heated feed roll was passed once through a pair of involute intermeshing gears, (containing teeth/inch on the circumference; diametral pitch 80), one gear being driven at a constant speed of 640 ft./rnin. by means of an electric motor whilst the second gear ran freely on a bearing and was driven by the first gear. The yarn then passed over a curved ribbonforming guide maintained at a temperature of 60-65 C. before running under tension, across the narrow surface of a heated tungsten strip and thence to the draw roll. The yarn was in contact with the surface of the strip for a distance of 0.030 inch and was deflected through a total angle of 18 by the strip. The tungsten strip was heated by contact with an electrically heated block containing a thermocouple fitted as close as possible to the front centre point of the strip contact area. The yarn samples were run with a temperature of 370 C. indicated by the thermocouple in the heater block. The yarn from the draw roll was then heat relaxed by overfeeding at a ratio of 1.4 (relax ratio) through a relaxation tube in which air introduced at a temperature of 210 C. was circulating. The yarn then passed from a take-up roll after the relax tube and was Wound onto a bobbin at a tension of 79 gms. The yarns were found to have crimped filaments in which the substantially helical crimp was of a random nature, varying in frequency and amplitude in a random manner within each filament and substantially out of phase from one filament to another. The specific volume of the yarn was measured as described and found to be 2.38 cc./g.

The apparatus referred to above is illustrated in the drawing wherein the following reference numerals indicate the elements of the apparatus: 10, melt spun feed stock; 12, yarn guide; 14, tension brake; 16, heated feed roll and idler; 18, pair of involute toothed intermeshing gears; 20, heated narrow surface; 22, draw roll and idler; 24, hot air relaxation tube; 2 6, relax roll and idler, and 28, wind-up unit.

Standard tensile tests were carried out on an Instron Tensile Tester and the yarn was found to have an initial modulus of 11.6 grams per denier, a breaking load of 442 grams, an extension at the breaking point of 56%, a yield point at 56 grams and a tenacity of 2578 grams per denier. The denier of the final product was 159.5 and the shrinkage in boiling water was 8.33%. The individual filaments exhibited a crimp count of from 68 crimps per inch to 0 crimps per inch.

The yarn was made up into small weft knitted samples on a 54 gauge head containing wales/ inch and knitting 32 courses/ inch. FIGURE 1 is a photomicrograph of one of these fabric samples. This fabric sample was then scoured for 10 minutes in a solution of Lissapol C (RTM) Powder (2 gms.) in boiling water (5000 ml.) and dyed for 5 minutes in a solution of Duranol (RTM) Blue GN (1 gm.) in boiling water (5000 ml.). FIGURE 2 is a photomicrograph of the treated fabric samples and shows how the bulk of the fabric sample was increased by the scouring and dyeing operations, resulting in a fabric of good cover and excellent stitch clarity.

For comparison purposes, a yarn was processed in the same way except that it was only passed across a heated narrow strip between the feed roll and the draw roll and did not pass through the gears. This yarn was then made into an identical fabric, a photomicrograph of which is shown in FIGURE 3.

The sample of FIGURE 3 was treated to the same scouring and dyeing treatment and a photomicrograph of the resulting fabric is shown in FIGURE 4. The superiority of the fabric shown in FIG. 1 over that shown in FIG. 3 is quite apparent, as is the superiority of the fabric shown in FIG. 2 over that shown in FIG. 4.

Example 2 The conditions and apparatus described in Example 1 were repeated for the drawspeeds and gear-speeds shown in Table I. After the relaxation treatment the yarns were shown to have the indicated specific volumes.

TABLE I Range of gearspeeds covered (in Range of specific Example 1 was again repeated varying the temperatures of the feed roll, of the tungsten strip (as measured by the heater block thermocouple) and of the hot air supplied to the relaxation tube. These temperatures, together with the specific volume of the yarn taken from the relaxation tube are set out in Table II.

TABLE II Tungsten strip Feed roll Relaxation tube Specific volume 0.) 0.) C.) (cc/gm.)

Example 4 Three samples, each of 15 filament 172 denier polyethylene terephthalate yarn, were processed in the manner and under the same conditions described in Example 1. The three samples were respectively (a) of circular filament section (b) of trilobal filament section having an aspect ratio of 1.78, and (c) of trilobal filament section having an aspect ratio of 2.62. The term aspect ratio is the ratio between the diameters of the escribed and circles of the filament cross-section.

The specific volumes of these yarns after the relaxation treatment were respectively measured as (a) 2.40 Cc./g., (b) 3.05 cc./g., and (c) 3.62 cc./g.

Example 5 A sample of 360 denier polyethylene terephthalate yarn having 36 filaments was melt spun, treated with a wet lubricating finish, and wound onto bobbins at a birefringence of 8.0 It was then drawn from a feed roll heated to 85 C. at a draw-speed of 900 .ft./min. and a draw ratio of 3.22:1. After leaving the feed roll the yarn was passed once through a pair of involute intermeshing gears (containing 20 teeth/inch on the circumference; diametral pitch 80), one gear, made of stainless steel being driven at a constant speed of 700 ft./min. whilst the second gear, made of aeetal resin, was run on a bearing and driven by the first gear. The yarn was then passed over a ceramic V-guide before running, under tension, across the narrow surface of a heated tungstencarbide strip identical with the tungsten strip described in Example 1 and thence to the draw roll. The ceramic V-guide was situated 4 inches from the heated strip and so positioned to give an angle of approach of the yarn to the hot strip of 20, and the yarn was deflected through a total angle of 24 by the strip. The yarn samples were made with a temperature of 350 C. indicated by the thermocouple in the heater block. The yarn passed from the draw roll to the relaxation tube described in Example 1, the circulating air being introduced at a temperature of 200 C. A relax ratio of 1.45:1 was used and the yarn wound up at a tension of 5-7 g. The specific volume of the resulting yarn was measured to be 2.43 cc./g. Fabrics knitted from this yarn showed good cover and excellent stitch clarity.

Example 6 A sample of 96 filament 1070 denier polyethylene terephthalate yarn was melt spun, treated with a wet lubricating finish, and wound onto bobbins at a birefringence of 8.0)(10' before being drawn from a feed roll heated to 100 C. at a draw speed 825 ft./min. at a draw ratio of 3.22:1.

The yarn then passed through the gears described in Example 5 whilst the steel gear was driven at 450 ft./min. The yarn then passed across the tungsten carbide strip whilst the heater block thermocouple measured 330 C. and then passed from the draw roll to the relaxation tube described in the previous examples. Air at 240 C. was supplied to the relaxation tube and a relax ratio of 2.021 was used. The yarn was wound up at a tension of g. and its specific volume was measured as 2.41 cc./g.

Example 7 Five samples of yarn produced as in Example 2 were wound into hanks (500 wraps x 1.125 metre). A sixth sample was produced in a similar fashion, except that the yarn passed over the heated strip before passing through the gears, and wound into a similar hank. For comparative purposes, a sample (c) of the yarn used to make the comparative fabric of Example 1 (FIG. 3) was also wound into a similar hank.

The hanks were scoured in a boiling aqueous solution of Lissapol C (RTM) (2 gms. in 1000 ml.) for 5 minutes. The hanks were carefully unwound and rewound onto cones and further specific volume determinations were carried out. Table III shows the increases in specific volume produced in the samples by the scouring operation.

TABLE III Specific volume Specific volume Bulk increase Sample before scouring after scouring (ec./g.)

( -lg.) c-la) 1 N 0 increase.

What is claimed is:

1. A method for producing a modified continuous filament polyester yarn by melt-spinning and drawing between a heated feed roll and a draw roll rotating faster than said feed roll, wherein the yarn, after passing the feed roll but before the draw roll passes between rotating intermeshing gears and also across a narrow surface heated to a temperature of at least C.

2. A process according to claim 1, wherein the narrow surface is heated to a temperature above the melting temperature of the polyester.

3. A process according to claim 2, wherein the yarn passes through the intermeshing gears before it passes across the heated narrow surface.

4. A process according to claim 2 wherein the yarn passes across the heated narrow surface before it passes through the intermeshing gears.

5. A process according to claim 1, wherein the yarn is further subjected to a relaxation treatment by heating under a reduced tension to a temperature above the second order transition temperature of the polyester and below the melting temperature of the polyester.

6. A process according to claim 5, wherein the yarn is further subjected for at least one minute to a scouring treatment in a boiling aqueous medium.

7. A process according to claim 6, wherein the yarn is knitted or woven into a fabric before said scouring treatment.

8. Apparatus for the production of modified continuous filament yarn from melt-spun synthetic filaments comprising a heatable feed roll and a draw roll arranged and adapted so that in operation the draw roll is rotated faster than the feed roll, and, interposed between said feed roll and the said draw roll, rotatable inter-meshing gearwheels adapted in operation to rotate at a speed greater than that of the feed roll but not greater than that of the draw roll and a heatable narrow surface arranged across said filament path.

9. Apparatus according to claim 8, further comprising a relaxation chamber arranged so that in operation yarn is overfed from the draw-roll into said chamber in which a current of heated air is circulated.

References Cited UNITED STATES PATENTS 3,024,517 3/ 1962 Bromley et al. 2872 3,137,911 6/1964 Bromley 28-1 3,217,376 11/1965 II'Win et al. 28-1 3,293,843 12/1966 Bibby et al 2872 X LOUIS K. RIMRODT, Primary Examiner.

U.S. Cl. X.R.

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