Title of Invention	METHOD AND QUENCH APPARATUS FOR MELT SPINNING OF CONTINUOUS POLYMERIC FILAMENT YARNS
Abstract	A method and quench apparatus (1) for melt spinning of continuous polymeric filament yarns having enhanced fiber uniformity with increased productivity. Polymeric filaments (15) are extruded from a molten polymeric material (not shown) through the capillaries (not shown) in the spinneret (2). The filaments are cooled in the quench apparatus located underneath the spinneret and comprising a cooling chamber (6) formed of a foraminous section (7a) and a non-foraminous section (7b) and a jacket(8) located around the cooling chamber in spaced apart relationship therewith to form a plenum chamber (9) for a cooling gas (not shown) entering the quench apparatus through a gas inlet (10) provided with the jacket. The filaments pass through the foraminous section over an oblong baffle (11) extending from the bottom surface of the spinneret centrally along the cooling chamber and a cooling gas is allowed to flow onto the filaments. The baffle directs the cooling gas downward to quench the filaments by concurrent flow of the cooling gas. The baffle extends from the bottom surface of the spinneret at least upto 40% of the cooling chamber describing a clearance with the capillaries in the spinneret. The filaments exiting the foraminous section are subjected to delayed cooling by accelerating the cooling gas at the exit of the foraminous section by passing the cooling gas and the filaments through a constricted tube (12) of reduced dimensions provided centrally at the exit of the foraminous section. The constricted tube has a convergent section (13) at its inlet end and optionally a divergent section (14) at its outlet end. The filament yarns exiting the constricted tube are wound on a winding device at a winding speed of at least 3000 m/min (Fig 1).

Title of Invention

METHOD AND QUENCH APPARATUS FOR MELT SPINNING OF CONTINUOUS POLYMERIC FILAMENT YARNS

Abstract

A method and quench apparatus (1) for melt spinning of continuous polymeric filament yarns having enhanced fiber uniformity with increased productivity. Polymeric filaments (15) are extruded from a molten polymeric material (not shown) through the capillaries (not shown) in the spinneret (2). The filaments are cooled in the quench apparatus located underneath the spinneret and comprising a cooling chamber (6) formed of a foraminous section (7a) and a non-foraminous section (7b) and a jacket(8) located around the cooling chamber in spaced apart relationship therewith to form a plenum chamber (9) for a cooling gas (not shown) entering the quench apparatus through a gas inlet (10) provided with the jacket. The filaments pass through the foraminous section over an oblong baffle (11) extending from the bottom surface of the spinneret centrally along the cooling chamber and a cooling gas is allowed to flow onto the filaments. The baffle directs the cooling gas downward to quench the filaments by concurrent flow of the cooling gas. The baffle extends from the bottom surface of the spinneret at least upto 40% of the cooling chamber describing a clearance with the capillaries in the spinneret. The filaments exiting the foraminous section are subjected to delayed cooling by accelerating the cooling gas at the exit of the foraminous section by passing the cooling gas and the filaments through a constricted tube (12) of reduced dimensions provided centrally at the exit of the foraminous section. The constricted tube has a convergent section (13) at its inlet end and optionally a divergent section (14) at its outlet end. The filament yarns exiting the constricted tube are wound on a winding device at a winding speed of at least 3000 m/min (Fig 1).

Full Text	FORM 2 THE PATENTS ACT, 1970 (39 OF 1970) As amended by the Patents (Amendment) Act, 2005 & The Patents Rules, 2003 As amended by the Patents (Amendment) Rules, 2006 COMPLETE SPECIFICATION (See section 10 and rule 13) TITLE OF THE INVENTION Continuous polymeric filament yarns having enhanced fiber uniformity with increased productivity INVENTORS Agarwal Uday Shankar, Chatterjee Sumanta, Hebbar Prasanna, Thampi Sumesh, Mukhopadhyay Partho, Seth Kishan Kumar and Aneja Arun Pal, all Indian Nationals except Aneja Arun Pal who is a US national and all of Reliance Industries Limited, B-4 MIDC Industrial Area, Patalganga -410220, Dist Raigad, Maharashtra, India APPLICANTS Reliance Industries Limited, an Indian Company, Maker Chambers IV, Nariman Point, Mumbai - 400 021, Maharashtra, India PREAMBLE TO THE DESCRIPTION The following specification particularly describes the nature of this invention and the manner in which it is to be performed : FIELD OF THE INVENTION This invention relates to continuous polymeric filament yams having enhanced fiber uniformity with increased productivity. This invention also relates to a method and quench apparatus for melt spinning of continuous polymeric filament yams. BACKGROUND OF THE INVENTION Man-made fibers are commercially produced by melt spinning comprising extrusion of polymeric filaments from a molten polymeric material through the capillaries or holes in the spinneret followed by simultaneous attenuation and quenching and solidification of the filaments in a quench apparatus located below the spinneret. Melt spinning of filaments typically greater than 100 filaments or still greater than 500 filaments per spinneret at winding speeds less than 2500 m/min gives low oriented yarns (LOY) or polyester staple yarns. Such yams are further oriented in the subsequent processing like drawing. Melt spinning of filaments typically fewer than 250 filaments or still fewer than 150 filaments per spinneret at winding speeds greater than 2500 m/min gives continuous filament yams. Such yams are with various degrees of orientation and are partially, high or fully oriented and may or not require further orientation in the subsequent processing depending upon their degree of orientation. The yam emerging from the quench apparatus is passed through a finish application system and wound on a take up or winding device. A quench apparatus generally comprises a cooling chamber formed of a foraminous section and a non-foraminous section. A jacket is located around the cooling chamber in spaced apart relationship therewith to form a plenum chamber for the cooling gas entering the cooling chamber through a gas inlet provided with the jacket. Quenching of the filaments can be carried out by forcing cooling air to flow across the filaments (Heckert, US 2,273,105) or concurrent to the filaments (Babcock, US 2,252,684). Quenching air also can be directed onto the filamentous structure in an outside-in manner. In order to eliminate air turbulence in the center of the filament bundle and non-uniformities and interfilament fusion and to improve quenching and filament quality, a generally cylindrical baffle or gas damper extending axially from the lower face of the spinneret downward into the cooling chamber is described by Charlton, US 3,299,469. The baffle helps to streamline the flow of the cooling air to quench the filament bundle by concurrent flow of the cooling gas. It is reported that the quality of the spun filaments is improved in the sense that both denier and dyeing non-uniformities are substantially eliminated and the uniformity of tenacity and break elongation values are greatly improved. It is also reported to provide 20 to 50% increase in fiber productivity by closer spacing of holes in the spinneret. The incidence of undrawns and fused fibers is reduced during spinning of a bundle of 600 filaments of polyethylene terephthalate at take up speed of 1460 m/min (Example 1) which is typically low oriented yarn (LOY). Vassilatos (US 4,687,610), Sweet et al (US 5,824,248) and Anderson et al (US 6,090,485) teach that partially oriented yarn (suitable for draw feed yarns such as for draw texturizing) of high uniformity and low denier spread can be made by accelerating the quenching gas along the threadline by passing through a tube of reduced dimensions provided at the exit of the foraminous section. This also is reported to increase the elongation of the yarn. Mears (US 5,976,431) describes that air current may be so generated as to contact the filaments a short distance below the spinneret to avoid a sharp drop in temperature. Additionally, means can be provided at the lower end of the quenching chamber for drawing a negative pressure. Air stream assists the filaments in their advance in the cooling chamber. This delays the filament solidification and polymer crystallization and allows production of yarn at higher winding speed without decreasing the elongation. However, in the case of coarser filament deniers, the cooling may not be adequate. Further, the filament denier uniformity may not be high and may cause deterioration of the successive processing performance (eg Unitens T2 variations during draw texturing) and final product properties such as dyeing uniformity. The high level of rejection of the product due to this renders the process unprofitable. Further variations have been discussed for increasing the uniformity eg by introducing additional air to contact the filaments only shortly before or after solidification of the filaments (Schafer et al, US 6,716,014) or by providing a negative pressure at the lower end of the tube for drawing quench air (Mears US 5,976,431). Such hardware components add to the operational difficulties as well as operational costs. OBJECTS OF THE INVENTION A main object of the invention is to provide continuous polymeric filament yarns having enhanced fiber uniformity with increased winding speed or productivity. Another object of the invention is to provide a method for melt spinning of continuous polymeric filament yarns having enhanced fiber uniformity with increased winding speed or productivity. Another object of the invention is to provide a quench apparatus for use in the melt spinning of continuous polymeric filament yarns having enhanced fiber uniformity with increased winding speed or productivity. Another object of the invention is to provide a quench apparatus for use in the melt spinning of continuous polymeric filament yarns, which apparatus is easy and convenient to clean and maintain. SUMMARY OF THE INVENTION The invention provides continuous polymeric filament yarns having enhanced fiber uniformity with increased productivity. The invention also provides a method and quench apparatus for melt-spinning of continuous polymeric filament yarns that employs a baffle extending centrally along the cooling chamber of the quench apparatus in combination with a constricted tube of reduced dimensions provided centrally at the exit of the foraminous section of the cooling chamber for reducing air turbulence and fusion of the filaments and for acceleration of the quenching gas along the threadline so as to substantially improve fiber uniformity and quality with increased winding speed or productivity. The constricted tube describes a converging section at the entry thereof and optionally a diverging section at the exit thereof. At high winding speeds, the invention reduces the non-uniformities in filament denier (Uster, half inert) and also reduces the non-uniformities in mechanical properties like tenacity or elongation. It further reduces variations in the T2 (Unitens) during subsequent processing (such as draw texturizing) and in the dye strength (TKD: Tube Knitted Dyeing). Further, it reduces the OLT (On-line Tension) rejects, body-breaks, splice fails, or broken filaments. Further, it provides for increase in filament productivity by further delaying the quenching and crystallization. The method for melt spinning of continuous polymeric filament yarns according to the invention comprises the following steps : i) extruding polymeric filaments from a molten polymeric material through the capillaries in the spinneret; ii) cooling the filaments in a quench apparatus located underneath the spinneret and comprising a cooling chamber formed of a foraminous section and a non-foraminous section and a jacket located around the cooling chamber in spaced apart relationship therewith to form a plenum chamber for a cooling gas entering the quench apparatus through a gas inlet provided with the jacket, cooling of the filaments being carried out by passing the filaments through the foraminous section over an oblong baffle extending from the bottom surface of the spinneret centrally along the cooling chamber and allowing the cooling gas to flow onto the filaments, the baffle directing the cooling gas downward to quench the filaments by concurrent flow of the cooling gas, the baffle extending from the bottom surface of the spinneret at least upto 40% of the cooling chamber describing a clearance with the capillaries in the spinneret; iii) subjecting the filaments exiting the foraminous section to delayed cooling by accelerating the cooling gas at the exit of the foraminous section by passing the cooling gas and the filaments through a constricted tube of reduced dimensions provided centrally at the exit of the foraminous section, the constricted tube having a convergent section at its inlet end and optionally a divergent section at its outlet end and iv) winding the filament yarns exiting the constricted tube on a winding device at a winding speed of at least 3000 m/min. The quench apparatus for use in the melt spinning of continuous polymeric filament yarns according to the invention comprises a cooling chamber formed of a foraminous section and a non-foraminous section, a jacket provided around the cooling chamber in spaced apart relationship therewith to form a plenum chamber for a cooling gas entering the quench apparatus through a gas inlet provided with the jacket, an oblong baffle extending from the bottom surface of the spinneret centrally along the cooling chamber so as to direct the cooling gas downward to quench the filaments by concurrent flow of the cooling gas, the baffle extending from the bottom surface of the spinneret at least upto 40% of the cooling chamber describing a clearance with the capillaries in the spinneret and a constricted tube of reduced dimensions provided centrally at the exit of the foraminous section for exiting the cooling gas and filaments, the constricted tube having a convergent section at its inlet end and optionally a divergent section at its outlet end, the constricted tube accelerating the cooling gas at the exit of the foraminous section so as to delay the cooling of the filaments exiting the foraminous section. According to the invention there is also provided continuous polymeric filament yarns having enhanced fiber uniformity including reduced half inert upto 0.15 with increased productivity. The following is a detailed description of the invention with reference to the accompanying drawings, in which Fig 1 is a schematic crosssectional view of the quench apparatus for use in the melt spinning of continuous polymeric filament yarns according to an embodiment of the invention; Figs 2a, 2b and 2c are schematic views of baffles of different geometries according to different embodiments of the invention; Fig 3 is a schematic crosssectional view of a spinneret and baffle combination according to an embodiment of the invention; and Fig 4 is a schematic crosssectional view of a spinneret and baffle combination according to another embodiment of the invention. The quench apparatus 1 as illustrated in Fig 1 of the accompanying drawings is located underneath a spinneret 2 comprising a plurality of capillaries or holes (not shown) provided therein and housed in a spin pack 3. The configuration and layout of the capillaries or holes in the spinneret will vary depending upon the design requirements of the spinneret. 4 and 5 are the spin-block and blind respectively. The quench apparatus comprises a cooling chamber 6 formed of a foraminous section 7a and a non-foraminous section 7b. 8 is a jacket provided around the cooling chamber in spaced apart relationship therewith to form a plenum chamber 9 for a cooling gas (not shown) entering the quench apparatus through a cooling gas inlet 10 provided with the jacket. 11 is an oblong conical baffle extending from the bottom surface of the spinneret centrally along the cooling chamber. 12 is a constricted tube of reduced dimensions provided centrally at the exit of the foraminous section. The constricted tube describes a convergent section 13 at the inlet end thereof and a divergent section 14 at the outlet end thereof. The divergent section at the outlet end of the constricted tube is, however, optional. Polymeric filaments marked 15 are extruded from a molten polymeric material (not shown) through the capillaries in the spinneret in known manner. The polymeric material used in the invention for making the filaments include polyesters such as polyethyleneterephthalate, polybutylenes terephthalate, polytrimethylene terephthalate, polyamides or polyolefins or copolymers/blends thereof as well as bicomponent filaments. The filaments are allowed to pass through the cooling chamber over the oblong conical baffle. Simultaneously a cooling gas (not shown) is allowed to flow into the foraminous section in an outside-in manner. Instead, flow of the cooling gas into the foraminous section also can be across or concurrent to the filaments. The baffle directs the cooling gas downward in the cooling chamber to quench the filaments by concurrent flow of the cooling gas. The baffle helps to avoid turbulence and ensure smooth flow of the filaments and prevent fusion of the filaments. The filaments and cooling gas exiting the foraminous section pass through the constricted tube. The convergent section at the inlet end of the constricted tube helps to converge the cooling gas into the constricted tube. In the constricted tube, the flow of the cooling medium is accelerated. Due to acceleration of the cooling gas, the filaments in the constricted tube are cooled in a delayed manner and solidification and crystallization of the filaments are correspondingly slowed down. The divergent section at the outlet end of the constricted tube prevents sudden expansion of the cooling gas and turbulence in the constricted tube. On exit from the constricted tube, the filaments bundle / yarn is passed through a finish application system (not shown) and wound on a take up device (not shown) at a winding speed of at least 3200 m/min, preferably at a winding speed >3500 m/min and still preferably at a winding speed >4000 m/min. The number of filaments extruded per spinneret according to the invention is 10 - 250, preferably 20 - 150. The baffle may have different geometries. It may be conical as illustrated in Fig 1 of the accompanying drawings, conical shaped with a concave outer surface as illustrated in Fig 2a of the accompanying drawings or conical shaped with a convex outer surface as illustrated in Fig 2b of the accompanying drawings or partly cylindrical and partly conical as illustrated in Fig 2c of the accompanying drawings. The conical portion of the baffle as illustrated in Fig 2c may be with a concave or convex outer surface. The baffles may be solid or hollow or porous. The baffle extends centrally from the bottom surface of the spinneret atleast upto 40% of the cooling chamber describing a clearance with the capillaries in the spinneret. It can also extend upto 40 to 100% of the cooling chamber or even into the constricted tube partly. Preferably, the capillaries in the spinneret are in one circle or two or more concentric circles and the top surface area of the baffle is 20 to 80%) of the bottom surface area of the spinneret within the circle of capillaries in the spinneret or the inner or innermost circle of capillaries in the spinneret and the bottom surface area of the baffle is 0 to 80% of the bottom surface area of the spinneret within the circle of capillaries in the spinneret or the inner or innermost circle of capillaries in the spinneret. The baffle can be made of any material sufficiently stable at the temperature experienced by it and sufficiently thermally non-conducting or insulating so as to limit loss of spinneret heat through the large area of the baffle. The baffle may be thermally insulated from the spinneret using a thermal insulator sleeve (not shown) between the baffle and the corresponding engaging part of the spinneret. The baffle may be rigidly fitted to the spinneret or integrally formed with it. Alternatively the baffle may be detachable as illustrated in Figs 3 and 4 of the accompanying drawings. In Fig 3 the baffle 16 is provided with an externally threaded tongue 17 at its top end and the spinneret 18 is provided with a corresponding groove 19 at its bottom surface. The threads on the tongue are marked 17a. The groove has threads marked 19a on the sidewall thereof matching with the threads on the tongue. The baffle is detachably fitted at the bottom surface of the spinneret by locating the tongue in the groove in thread engagement therewith. In Fig 4, the baffle 20 is provided with an oblong slot 21 one end of which is closed and the other end of which is extending upto the top end of the baffle. 22 is a collar provided at the top end of the baffle and formed with a through hole 23 in alignment with the oblong slot in the baffle. The collar is externally threaded (threads marked 22a). The spinneret 24 is provided with a socket 25 at its bottom surface corresponding to the collar. The sidewall of the socket is threaded (threads marked 25a) corresponding to the threading on the collar. 26 is a rod engaged in the through hole in the collar. One end of the rod extends into the oblong slot through the through hole in the collar and is provided with a stopper 27 adapted to abut against the bottom end of the collar. The other end of the rod is provided with a locator disc 28 having threads 28a on the outer circumference thereof corresponding to the threading 25a at the sidewall of the socket. The collar with the baffle is slidably held over the rod. The locator disc is detachably located in the socket in thread engagement therewith and the collar is detachably fitted in the socket in thread engagement therewith below the locator disc. The detachability of the baffle from the spinneret helps to clean and maintain the spinneret surface by detaching only the baffle and without the detaching the spinneret. Therefore, cleaning and maintenance of the spinneret becomes easy and convenient. In the case of the baffle in Fig 4, it can be detached from the spinneret by detaching the collar and made to slide down along the rod without getting detached from the rod for accessibility to the spinneret for cleaning and maintenance. On completion of the cleaning and maintenance work, the baffle can be slid up along the rod and the collar can be fitted in the socket at the bottom surface of the spinneret. The baffle can be completely detached from the spinneret by unscrewing the locator disc from the socket at the bottom surface of the spinneret. Instead of thread fit between the tongue and the groove in the case of the baffle of Fig 3 and the collar and the socket in the case of the baffle of Fig 4, the baffle can be push or press fitted or snap fitted in the spinneret. According to the invention, the quality and uniformity of the filament yarns are substantially increased besides the winding speed or productivity as exemplified by the following non-limiting comparative Examples : Evenness of the melt spun filament thickness (linear density) on various length scales were measured in the following Examples using the uster tester apparatus (model Uster Tester 4 - CX of Uster Technologies, Switzerland) as uster (overall mass variation in % from mean mass, based on normal cut-length of 1 cm) and uster half inert (medium term irregularity of mass, based on cut-length of 6.4 m at speed of 400 m/min) values. Dynamic shrinkage force (Draw tension, DT) of the partially oriented yarn (POY) yarn was measured on (Lenzing Model DTI 400) using ASTM method No. D 5344. Break elongation and tenacity were determined on a table model Statimat M (TexTechno), using gage length 150 mm, and elongation rate 600 mm/min. Variation from average value was calculated as CV (coefficient of variation)%. The number of broken filaments during texturing that may be tolerated in practice will depend upon the intended use for the textured yarn and eventual fabric. In practice, in the trade, the ends of the bobbin are examined for broken filaments, and the number of protruding broken filaments is counted so as to give a measure of the probable number of broken filaments in the yarn of that package The total number of these broken filaments (BF) counted is then divided by the number of kg in the package and expressed as BF. On-line Tension sensor (OLT) was used to determine the yarn line tension during texturing. The post twist unit tension (T2) was measured online using the Unitens , (Brochure Tex 303e /5-4, Studio 45 / Koch of Barmag Oerllikon Saurer) and floating mean value, peak detection and CV% were computed. It is desirable to have T2 relatively free of peaks during the texturing of POY (Partially Oriented Yarn) bobbin, and it is characterized in terms of T2 tension variation (CV%) and presence of peaks. OLT rejects refers to the % of bobbins for which during texturing the T2 tension limits (+/- 2 cN) are exceeded. OLT sensors were also used to detect yarn break during texturing. Body breaks refer to number of yarn breakage during texturing of each tonne of yarn. Splice fail refers to failure of joining yarn while transferring from one POY bobbin to another. Example 1 Polyethylene terephthalate of intrinsic viscosity 0.605 dL/g (phenol-tetrachloroethane solvent, 60:40 wt ratio, 30°C, 0.5 g/cc, as per ASTM D 4603-03) was extruded at 288°C through the spinneret containing 48 holes of diameter 0.36 mm arranged equidistantly in a single circle of diameter 85 mm. The filaments were passed through a quench apparatus comprising a cylindrical cooling chamber formed of a foraminous section of 10 screens (alternating 100 mesh and 50 mesh) of inside diameter 95 mm and length 190 mm. The non-foraminous section of the cooling chamber had a length of 160 mm. Spin block and blind provided quench delays of 20 mm and 30 mm respectively. The filaments were cooled in the foraminous section with quench air applied through the foraminous section in an outside-in manner at diffuser pressure of 80 Pa. The filament yarns exiting from the cooling chamber was passed through a finish application system and then to a take up device at a winding speed of 3155 m/min. The test results were as shown in the following Table 1. Example 2 Polymeric filaments were extruded and quenched in a quench apparatus as described in Example 1 including a conical baffle extending centrally along the length of the cooling chamber. The baffle had a top diameter of 50 mm and length of 300 mm. The test results at a winding speed of 3155 m/min were as shown in the following Table 1. Example 3 Polymeric filaments were extruded and quenched in a quench apparatus as described in Example 1 including a constricted tube provided centrally at the exit of the foraminous section. The constricted tube had an inner diameter of 28 mm and length of 425 mm. The constricted tube had a convergent section at its inlet end with an outer end diameter of 94.5 mm and a divergent section as its outlet end with an outer end diameter of 63 mm. The cooling gas diffuser pressure outside the foraminous section of the cooling chamber was 800 Pa. The test results at winding speeds of 4300 m/min and 4420 m/min were as shown in the following Table 1. Example 4 Polymeric filaments were extruded and quenched in a quench apparatus as described in Example 1 including a baffle described in Example 2 and a constricted tube described in Example 3. The cooling gas diffuser pressure outside the foraminous section of the cooling chamber was 800 Pa. The test results at winding speeds of 4300 m/min and 4420 m/min were as shown in the following Table 1. Table 1 Example 1 Example 2 Example 3 Example 4 WindingSpeed(m/min) 3155 3155 4300 4420 4300 4420 Filament characteristics DT(g) 89 88.2 87.6 101.6 74 87.4 Uster 0.85 0.73 0.93 0.98 0.93 0.97 Half Inert 0.54 0.20 0.39 0.36 0.11 0.12 In Examples 1 to 4, the polymer throughout was adjusted to obtain yarns of 250 denier. In Examples 1 and 2, the filament characteristics deteriorated on increasing the winding speed above 3155 m/min. It is quite evident in the comparative study in Table 1 that the DT and half inert of the filament yarns obtained by Example 4 were considerably reduced as compared to Example 3 at the same high winding speeds of 4300 m/min and 4420 m/min. Half inert of filament yarns obtained by Example 4 were also considerably reduced at high winding speeds of 4300 m/min and 4420 m/min as compared to Example 2 employing lower speed of 3155 m/min. DT of Example 4 at 4420 m/min was lesser or almost the same as that of Example 2. The reduced half inert of filament yarns of Example 4 indicates that the medium range uniformity of the yarns is increased. The low half inert and comparable uster also indicate the improved denier of the yarn. In addition, the reduced DT value at 4300 m/min indicates that the yarn produced can be drawn to a larger extent during the subsequent steps such as texturing or draw-twisting so as to give increased productivity of the subsequent process. If, however, this possibility (increasing winding speed and productivity) is not utilized during such melt spinning, the lower DT of the melt spun filaments allows an increased productivity during the subsequent drawing process. According to the invention, there is thus achieved increased fiber uniformity with increased productivity by way of increased winding speed during melt spinning. The overall improvements in the product characteristics in terms of Half inert, uster and DT with increased productivity as obtained in Example 4 clearly establish the synergy or combined effect and functional cooperation of the component parts of the quench apparatus of the invention, especially the baffle and constricted tube combination. This is undoubtedly a new finding and technical advance in melt spinning technology. Continuous polymeric filament yarns having such enhanced fiber uniformity especially low half inert upto 0.15 with increased productivity are considered to be novel. Example 5 The filament samples made as in Example 3 (winding speed 4300 m/min) and Example 4 (winding speed 4420 m/min) were draw textured (draw ratio 1.7) on a Barmag FK6-1000 M Type Pilot machine at 900 m/min for processibility characteristics and physical characteristics of the filaments (T2 tension, OLT rejects, body-breaks, splice fails) as well as for filament breaks and mechanical properties (tenacity and elongation). The test results were as shown in the following Table 2 : Table 2 Processability characteristics Example 3 Example 4 Unitens T2 (g) 52 51.5 Individual position CV% mean 1.1 0.8 Peaks in tension during process Repeated tension peaks observed on certain polyester yarn spools No tension peaks observed on the polyester yarn spools OLT REJECTION 10% Nil Body Breaks / ton 26 Nil Total Breaks / ton (splice fail+body) 69 Nil % of spools containing no broken filaments (> 2 mm ) Nil 63 Broken filaments / kg 0.71 0.08 Elongation % 23 23 Elongation CV% 0.9 0.3 Tenacity (gpd) 4.5 4.4 Tenacity CV% 0.15 0.05 Table 2 shows the improved yarn characteristics of Example 4 as compared to those of Example 3. The improved characteristics during texturing indicate the possibility of enhanced uniform dyeing and dimensional stability of the textured product package spool. Table 2 further shows that the yield is increased in the case of filament yarns of Example 4 during the texturing by reducing breaks. Product uniformity is also improved in the case of filaments of Example 4 as indicated by reduced CV of the mechanical properties ie elongation and tenacity. Table 2 is further illustrative of the synergy or combinational effect and technical advance of the quench apparatus of the invention. Example 6 The procedure of Example 4 was carried out with baffles of different geometries and the test results at winding speed of 4300 m/min and diffuser pressure of 800 Pa were as shown in the following Table 3 : Table 3 Baffle type Cylinder Truncated-cone Cone top dia (mm) 27 50 50 length (mm) 200 200 300 Uster 1.15 1.28 0.93 Half Inert 0.30 0.38 0.11 Truncated-cone bottom diameter was 17 mm. Table 3 shows that the uster / half inert changed depending upon the baffle geometries. Table 3 also shows that conical baffle gave reduced uster and half inert and is preferable. We claim: 1. A method for melt spinning of continuous polymeric filament yarns having enhanced fiber uniformity with increased productivity, the method comprising : i) extruding polymeric filaments from a molten polymeric material through the capillaries in the spinneret; ii) cooling the filaments in a quench apparatus located underneath the spinneret and comprising a cooling chamber formed of a foraminous section and a non-foraminous section and a jacket located around the cooling chamber in spaced apart relationship therewith to form a plenum chamber for a cooling gas entering the quench apparatus through a gas inlet provided with the jacket, cooling of the filaments being carried out by passing the filaments through the foraminous section over an oblong baffle extending from the bottom surface of the spinneret centrally along the cooling chamber and allowing the cooling gas to flow onto the filaments, the baffle directing the cooling gas downward to quench the filaments by concurrent flow of the cooling gas, the baffle extending from the bottom surface of the spinneret at least upto 40% of the cooling chamber describing a clearance with the capillaries in the spinneret; iii) subjecting the filaments exiting the foraminous section to delayed cooling by accelerating the cooling gas at the exit of the foraminous section by passing the cooling gas and the filaments through a constricted tube of reduced dimensions provided centrally at the exit of the foraminous section, the constricted tube having a convergent section at its inlet end and optionally a divergent section at its outlet end; and iv) winding the filament yarns exiting the constricted tube on a winding device at a winding speed of at least 3000 m/min. 2. The method as claimed in claim 1, wherein the extrusion of the polymeric filaments is carried out in a spinneret having the capillaries in a circle or in a plurality of concentric circles and the cooling of the filaments is carried by passing the filaments over a baffle having a top surface area of 20 to 80% of the bottom surface area of the spinneret within the circle of capillaries in the spinneret or inner or innermost circle of capillaries in the spinneret and a bottom surface area of 0 to 80% of the bottom surface area of the spinneret within the circle of capillaries in the spinneret or inner or innermost circle of capillaries in the spinneret. 3. The method as claimed in claim 1 or 2, which is carried out at a winding speed >3500 m/min. 4. The method as claimed in claim 1 or 2, which is carried out at a winding speed >4000 m/min. 5. The method as claimed in anyone of claims 1 to 4, wherein the cooling gas is allowed to flow into the foraminous section in an outside-in manner. 6. Continuous polymeric filament yarns having enhanced fiber uniformity with increased productivity. 7. Continuous polymeric filament yarns having enhanced fiber uniformity including reduced half inert upto 0.15 with increased productivity. 8. A quench apparatus for use in the melt spinning of continuous polymeric filament yarns having enhanced fiber uniformity with increased productivity from a molten polymeric material through the capillaries of the spinneret, the quench apparatus being located underneath the spinneret and comprising a cooling chamber formed of a foraminous section and a non-foraminous section, a jacket provided around the cooling chamber in spaced apart relationship therewith to form a plenum chamber for a cooling gas entering the quench apparatus through a gas inlet provided with the jacket, an oblong baffle extending from the bottom surface of the spinneret centrally along the cooling chamber so as to direct the cooling gas downward to quench the filaments by concurrent flow of the cooling gas, the baffle extending from the bottom surface of the spinneret at least upto 40% of the cooling chamber describing a clearance with the capillaries in the spinneret and a constricted tube of reduced dimensions provided centrally at the exit of the foraminous section for exiting the cooling gas and filaments, the constricted tube having a convergent section at its inlet end and optionally a divergent section at its outlet end, the constricted tube accelerating the cooling gas at the exit of the foraminous section so as to delay the cooling of the filaments exiting the foraminous section. 9. The quench apparatus as claimed in claim 8, wherein the spinneret comprises capillaries provided in a circle or in a plurality of concentric circles and the baffle has a top surface area of 20 to 80% of the bottom surface area of the spinneret within the circle of capillaries in the spinneret or inner or innermost circle of capillaries in the spinneret and a bottom surface area of 0 to 80% of the bottom surface area of the spinneret within the circle of capillaries in the spinneret or inner or innermost circle of capillaries in the spinneret. 10. The quench apparatus as claimed in claim 8 or 9, which is used for melt spinning of continuous polymeric filament yarns at a winding speed >3500 m/min. 11. The quench apparatus as claimed in claim 8 or 9, which is used for melt spinning of continuous polymeric filament yarns at a winding speed >4000 m/min. 12. The quench apparatus as claimed in anyone of claims 8 to 11, wherein the baffle is solid, porous or hollow and is conical shaped, conical shaped with a concave or convex outer surface, partly cylindrical and partly conical or partly cylindrical and partly conical with a concave or convex outer surface. 13. The quench apparatus as claimed in anyone of claims 8 to 12 which is configured to allow outside-in flow of the cooling gas into the foraminous section. 14. The quench apparatus as claimed in anyone of claims 8 to 13, wherein the baffle is detachably fitted at the bottom surface of the spinneret. 15. The quench apparatus as claimed in claim 14, wherein the baffle is provided with an externally threaded tongue at its top end and the spinneret is provided with a corresponding groove at its bottom surface, the groove having threads on the sidewall thereof matching with the threads on the tongue, the baffle being detachably fitted at the bottom surface of the spinneret by locating the tongue at the top end thereof in the groove at the bottom surface of the spinneret in thread engagement therewith. 16. The quench apparatus as claimed in claim 14, wherein the baffle is provided with an oblong slot one end of which is closed and the other end of which is extending upto the top end of the baffle, a collar provided at the top end of the baffle and formed with a through hole in alignment with the oblong slot, the collar being externally threaded, the spinneret is provided with a socket at its bottom surface corresponding to the collar, the sidewall of the socket being threaded corresponding to the threading on the collar, a rod engaged in the through hole in the collar, one end of the rod extending into the oblong slot through the through hole in the collar and provided with a stopper adapted to abut against the bottom end of the collar and the other end of the rod being provided with a locator disc having threads on the outer circumference thereof corresponding to the threading at the sidewall of the socket, the collar with the baffle being slidably held over the rod, the locator disc being adapted to be detachably located in the socket in thread engagement therewith and the collar being adapted to be detachably fitted in the socket in thread engagement therewith below the locator disc. 17. The quench apparatus as claimed in anyone of claims 8 to 16, wherein the baffle extends upto 40 to 100% of the cooling chamber or into the constricted tube partly. ABSTRACT A method and quench apparatus (1) for melt spinning of continuous polymeric filament yarns having enhanced fiber uniformity with increased productivity. Polymeric filaments (15) are extruded from a molten polymeric material (not shown) through the capillaries (not shown) in the spinneret (2). The filaments are cooled in the quench apparatus located underneath the spinneret and comprising a cooling chamber (6) formed of a foraminous section (7a) and a non-foraminous section (7b) and a jacket (8) located around the cooling chamber in spaced apart relationship therewith to form a plenum chamber (9) for a cooling gas (not shown) entering the quench apparatus through a gas inlet (10) provided with the jacket. The filaments pass through the foraminous section over an oblong baffle (11) extending from the bottom surface of the spinneret centrally along the cooling chamber and a cooling gas is allowed to flow onto the filaments. The baffle directs the cooling gas downward to quench the filaments by concurrent flow of the cooling gas. The baffle extends from the bottom surface of the spinneret at least upto 40% of the cooling chamber describing a clearance with the capillaries in the spinneret. The filaments exiting the foraminous section are subjected to delayed cooling by accelerating the cooling gas at the exit of the foraminous section by passing the cooling gas and the filaments through a constricted tube (12) of reduced dimensions provided centrally at the exit of the foraminous section. The constricted tube has a convergent section (13) at its inlet end and optionally a divergent section (14) at its outlet end. The filament yarns exiting the constricted tube are wound on a winding device at a winding speed of at least 3000 m/min(Fig 1).

Full Text

FORM 2
THE PATENTS ACT, 1970
(39 OF 1970)
As amended by the Patents (Amendment) Act, 2005
&
The Patents Rules, 2003
As amended by the Patents (Amendment) Rules, 2006
COMPLETE SPECIFICATION
(See section 10 and rule 13)
TITLE OF THE INVENTION
Continuous polymeric filament yarns having enhanced fiber uniformity with increased productivity
INVENTORS
Agarwal Uday Shankar, Chatterjee Sumanta, Hebbar Prasanna, Thampi Sumesh, Mukhopadhyay Partho, Seth Kishan Kumar and Aneja Arun Pal, all Indian Nationals except Aneja Arun Pal who is a US national and all of Reliance Industries Limited, B-4 MIDC Industrial Area, Patalganga -410220, Dist Raigad, Maharashtra, India
APPLICANTS
Reliance Industries Limited, an Indian Company, Maker Chambers IV, Nariman Point, Mumbai - 400 021, Maharashtra, India
PREAMBLE TO THE DESCRIPTION
The following specification particularly describes the nature of this invention and the manner in which it is to be performed :

FIELD OF THE INVENTION
This invention relates to continuous polymeric filament yams having enhanced fiber uniformity with increased productivity.
This invention also relates to a method and quench apparatus for melt spinning of continuous polymeric filament yams.
BACKGROUND OF THE INVENTION
Man-made fibers are commercially produced by melt spinning comprising extrusion of polymeric filaments from a molten polymeric material through the capillaries or holes in the spinneret followed by simultaneous attenuation and quenching and solidification of the filaments in a quench apparatus located below the spinneret. Melt spinning of filaments typically greater than 100 filaments or still greater than 500 filaments per spinneret at winding speeds less than 2500 m/min gives low oriented yarns (LOY) or polyester staple yarns. Such yams are further oriented in the subsequent processing like drawing. Melt spinning of filaments typically fewer than 250 filaments or still fewer than 150 filaments per spinneret at winding speeds greater than 2500 m/min gives continuous filament yams. Such yams are with various degrees of orientation and are partially, high or fully oriented and may or not require further orientation in the subsequent processing depending upon their degree of orientation. The yam emerging from the quench apparatus is passed through a finish application system and wound on a take up or winding device. A quench apparatus generally comprises a cooling chamber formed of a foraminous section and a non-foraminous section.

A jacket is located around the cooling chamber in spaced apart relationship therewith to form a plenum chamber for the cooling gas entering the cooling chamber through a gas inlet provided with the jacket. Quenching of the filaments can be carried out by forcing cooling air to flow across the filaments (Heckert, US 2,273,105) or concurrent to the filaments (Babcock, US 2,252,684). Quenching air also can be directed onto the filamentous structure in an outside-in manner. In order to eliminate air turbulence in the center of the filament bundle and non-uniformities and interfilament fusion and to improve quenching and filament quality, a generally cylindrical baffle or gas damper extending axially from the lower face of the spinneret downward into the cooling chamber is described by Charlton, US 3,299,469. The baffle helps to streamline the flow of the cooling air to quench the filament bundle by concurrent flow of the cooling gas. It is reported that the quality of the spun filaments is improved in the sense that both denier and dyeing non-uniformities are substantially eliminated and the uniformity of tenacity and break elongation values are greatly improved. It is also reported to provide 20 to 50% increase in fiber productivity by closer spacing of holes in the spinneret. The incidence of undrawns and fused fibers is reduced during spinning of a bundle of 600 filaments of polyethylene terephthalate at take up speed of 1460 m/min (Example 1) which is typically low oriented yarn (LOY).
Vassilatos (US 4,687,610), Sweet et al (US 5,824,248) and Anderson et al (US 6,090,485) teach that partially oriented yarn (suitable for draw feed yarns such as for draw texturizing) of high uniformity and low denier spread can be made by accelerating the quenching gas along the threadline by passing through a tube of reduced dimensions provided at the exit of the foraminous section. This also is reported to increase the

elongation of the yarn. Mears (US 5,976,431) describes that air current may be so generated as to contact the filaments a short distance below the spinneret to avoid a sharp drop in temperature. Additionally, means can be provided at the lower end of the quenching chamber for drawing a negative pressure. Air stream assists the filaments in their advance in the cooling chamber. This delays the filament solidification and polymer crystallization and allows production of yarn at higher winding speed without decreasing the elongation. However, in the case of coarser filament deniers, the cooling may not be adequate. Further, the filament denier uniformity may not be high and may cause deterioration of the successive processing performance (eg Unitens T2 variations during draw texturing) and final product properties such as dyeing uniformity. The high level of rejection of the product due to this renders the process unprofitable. Further variations have been discussed for increasing the uniformity eg by introducing additional air to contact the filaments only shortly before or after solidification of the filaments (Schafer et al, US 6,716,014) or by providing a negative pressure at the lower end of the tube for drawing quench air (Mears US 5,976,431). Such hardware components add to the operational difficulties as well as operational costs.
OBJECTS OF THE INVENTION
A main object of the invention is to provide continuous polymeric filament yarns having enhanced fiber uniformity with increased winding speed or productivity.
Another object of the invention is to provide a method for melt spinning of continuous polymeric filament yarns having enhanced fiber uniformity with increased winding speed or productivity.

Another object of the invention is to provide a quench apparatus for use in the melt spinning of continuous polymeric filament yarns having enhanced fiber uniformity with increased winding speed or productivity.
Another object of the invention is to provide a quench apparatus for use in the melt spinning of continuous polymeric filament yarns, which apparatus is easy and convenient to clean and maintain.
SUMMARY OF THE INVENTION
The invention provides continuous polymeric filament yarns having enhanced fiber uniformity with increased productivity. The invention also provides a method and quench apparatus for melt-spinning of continuous polymeric filament yarns that employs a baffle extending centrally along the cooling chamber of the quench apparatus in combination with a constricted tube of reduced dimensions provided centrally at the exit of the foraminous section of the cooling chamber for reducing air turbulence and fusion of the filaments and for acceleration of the quenching gas along the threadline so as to substantially improve fiber uniformity and quality with increased winding speed or productivity. The constricted tube describes a converging section at the entry thereof and optionally a diverging section at the exit thereof. At high winding speeds, the invention reduces the non-uniformities in filament denier (Uster, half inert) and also reduces the non-uniformities in mechanical properties like tenacity or elongation. It further reduces variations in the T2 (Unitens) during subsequent processing (such as draw texturizing) and in the dye strength (TKD: Tube Knitted Dyeing). Further, it reduces the OLT (On-line Tension) rejects, body-breaks, splice

fails, or broken filaments. Further, it provides for increase in filament productivity by further delaying the quenching and crystallization.
The method for melt spinning of continuous polymeric filament yarns
according to the invention comprises the following steps :
i) extruding polymeric filaments from a molten polymeric material
through the capillaries in the spinneret;
ii) cooling the filaments in a quench apparatus located underneath the
spinneret and comprising a cooling chamber formed of a foraminous
section and a non-foraminous section and a jacket located around the
cooling chamber in spaced apart relationship therewith to form a plenum
chamber for a cooling gas entering the quench apparatus through a gas
inlet provided with the jacket, cooling of the filaments being carried out
by passing the filaments through the foraminous section over an oblong
baffle extending from the bottom surface of the spinneret centrally along
the cooling chamber and allowing the cooling gas to flow onto the
filaments, the baffle directing the cooling gas downward to quench the
filaments by concurrent flow of the cooling gas, the baffle extending
from the bottom surface of the spinneret at least upto 40% of the cooling
chamber describing a clearance with the capillaries in the spinneret;
iii) subjecting the filaments exiting the foraminous section to
delayed cooling by accelerating the cooling gas at the exit of the foraminous section by passing the cooling gas and the filaments through a constricted tube of reduced dimensions provided centrally at the exit of the foraminous section, the constricted tube having a convergent section at its inlet end and optionally a divergent section at its outlet end and
iv) winding the filament yarns exiting the constricted tube on a
winding device at a winding speed of at least 3000 m/min.

The quench apparatus for use in the melt spinning of continuous polymeric filament yarns according to the invention comprises a cooling chamber formed of a foraminous section and a non-foraminous section, a jacket provided around the cooling chamber in spaced apart relationship therewith to form a plenum chamber for a cooling gas entering the quench apparatus through a gas inlet provided with the jacket, an oblong baffle extending from the bottom surface of the spinneret centrally along the cooling chamber so as to direct the cooling gas downward to quench the filaments by concurrent flow of the cooling gas, the baffle extending from the bottom surface of the spinneret at least upto 40% of the cooling chamber describing a clearance with the capillaries in the spinneret and a constricted tube of reduced dimensions provided centrally at the exit of the foraminous section for exiting the cooling gas and filaments, the constricted tube having a convergent section at its inlet end and optionally a divergent section at its outlet end, the constricted tube accelerating the cooling gas at the exit of the foraminous section so as to delay the cooling of the filaments exiting the foraminous section.
According to the invention there is also provided continuous polymeric filament yarns having enhanced fiber uniformity including reduced half inert upto 0.15 with increased productivity.
The following is a detailed description of the invention with reference to the accompanying drawings, in which

Fig 1 is a schematic crosssectional view of the quench apparatus for use in the melt spinning of continuous polymeric filament yarns according to an embodiment of the invention;
Figs 2a, 2b and 2c are schematic views of baffles of different geometries according to different embodiments of the invention;
Fig 3 is a schematic crosssectional view of a spinneret and baffle combination according to an embodiment of the invention; and
Fig 4 is a schematic crosssectional view of a spinneret and baffle combination according to another embodiment of the invention.
The quench apparatus 1 as illustrated in Fig 1 of the accompanying drawings is located underneath a spinneret 2 comprising a plurality of capillaries or holes (not shown) provided therein and housed in a spin pack 3. The configuration and layout of the capillaries or holes in the spinneret will vary depending upon the design requirements of the spinneret. 4 and 5 are the spin-block and blind respectively. The quench apparatus comprises a cooling chamber 6 formed of a foraminous section 7a and a non-foraminous section 7b. 8 is a jacket provided around the cooling chamber in spaced apart relationship therewith to form a plenum chamber 9 for a cooling gas (not shown) entering the quench apparatus through a cooling gas inlet 10 provided with the jacket. 11 is an oblong conical baffle extending from the bottom surface of the spinneret centrally along the cooling chamber. 12 is a constricted tube of reduced dimensions provided centrally at the exit of the foraminous section. The constricted tube describes a convergent section 13 at the inlet end thereof and a divergent section 14 at the outlet end thereof.

The divergent section at the outlet end of the constricted tube is, however, optional. Polymeric filaments marked 15 are extruded from a molten polymeric material (not shown) through the capillaries in the spinneret in known manner. The polymeric material used in the invention for making the filaments include polyesters such as polyethyleneterephthalate, polybutylenes terephthalate, polytrimethylene terephthalate, polyamides or polyolefins or copolymers/blends thereof as well as bicomponent filaments. The filaments are allowed to pass through the cooling chamber over the oblong conical baffle. Simultaneously a cooling gas (not shown) is allowed to flow into the foraminous section in an outside-in manner. Instead, flow of the cooling gas into the foraminous section also can be across or concurrent to the filaments. The baffle directs the cooling gas downward in the cooling chamber to quench the filaments by concurrent flow of the cooling gas. The baffle helps to avoid turbulence and ensure smooth flow of the filaments and prevent fusion of the filaments. The filaments and cooling gas exiting the foraminous section pass through the constricted tube. The convergent section at the inlet end of the constricted tube helps to converge the cooling gas into the constricted tube. In the constricted tube, the flow of the cooling medium is accelerated. Due to acceleration of the cooling gas, the filaments in the constricted tube are cooled in a delayed manner and solidification and crystallization of the filaments are correspondingly slowed down. The divergent section at the outlet end of the constricted tube prevents sudden expansion of the cooling gas and turbulence in the constricted tube. On exit from the constricted tube, the filaments bundle / yarn is passed through a finish application system (not shown) and wound on a take up device (not shown) at a winding speed of at least 3200 m/min, preferably at a winding speed >3500 m/min and still preferably at a winding speed

>4000 m/min. The number of filaments extruded per spinneret according to the invention is 10 - 250, preferably 20 - 150.
The baffle may have different geometries. It may be conical as illustrated in Fig 1 of the accompanying drawings, conical shaped with a concave outer surface as illustrated in Fig 2a of the accompanying drawings or conical shaped with a convex outer surface as illustrated in Fig 2b of the accompanying drawings or partly cylindrical and partly conical as illustrated in Fig 2c of the accompanying drawings. The conical portion of the baffle as illustrated in Fig 2c may be with a concave or convex outer surface. The baffles may be solid or hollow or porous. The baffle extends centrally from the bottom surface of the spinneret atleast upto 40% of the cooling chamber describing a clearance with the capillaries in the spinneret. It can also extend upto 40 to 100% of the cooling chamber or even into the constricted tube partly. Preferably, the capillaries in the spinneret are in one circle or two or more concentric circles and the top surface area of the baffle is 20 to 80%) of the bottom surface area of the spinneret within the circle of capillaries in the spinneret or the inner or innermost circle of capillaries in the spinneret and the bottom surface area of the baffle is 0 to 80% of the bottom surface area of the spinneret within the circle of capillaries in the spinneret or the inner or innermost circle of capillaries in the spinneret. The baffle can be made of any material sufficiently stable at the temperature experienced by it and sufficiently thermally non-conducting or insulating so as to limit loss of spinneret heat through the large area of the baffle. The baffle may be thermally insulated from the spinneret using a thermal insulator sleeve (not shown) between the baffle and the corresponding engaging part of the spinneret.

The baffle may be rigidly fitted to the spinneret or integrally formed with it. Alternatively the baffle may be detachable as illustrated in Figs 3 and 4 of the accompanying drawings. In Fig 3 the baffle 16 is provided with an externally threaded tongue 17 at its top end and the spinneret 18 is provided with a corresponding groove 19 at its bottom surface. The threads on the tongue are marked 17a. The groove has threads marked 19a on the sidewall thereof matching with the threads on the tongue. The baffle is detachably fitted at the bottom surface of the spinneret by locating the tongue in the groove in thread engagement therewith. In Fig 4, the baffle 20 is provided with an oblong slot 21 one end of which is closed and the other end of which is extending upto the top end of the baffle. 22 is a collar provided at the top end of the baffle and formed with a through hole 23 in alignment with the oblong slot in the baffle. The collar is externally threaded (threads marked 22a). The spinneret 24 is provided with a socket 25 at its bottom surface corresponding to the collar. The sidewall of the socket is threaded (threads marked 25a) corresponding to the threading on the collar. 26 is a rod engaged in the through hole in the collar. One end of the rod extends into the oblong slot through the through hole in the collar and is provided with a stopper 27 adapted to abut against the bottom end of the collar. The other end of the rod is provided with a locator disc 28 having threads 28a on the outer circumference thereof corresponding to the threading 25a at the sidewall of the socket. The collar with the baffle is slidably held over the rod. The locator disc is detachably located in the socket in thread engagement therewith and the collar is detachably fitted in the socket in thread engagement therewith below the locator disc. The detachability of the baffle from the spinneret helps to clean and maintain the spinneret surface by detaching only the baffle and without the detaching the spinneret. Therefore, cleaning and maintenance of the spinneret

becomes easy and convenient. In the case of the baffle in Fig 4, it can be detached from the spinneret by detaching the collar and made to slide down along the rod without getting detached from the rod for accessibility to the spinneret for cleaning and maintenance. On completion of the cleaning and maintenance work, the baffle can be slid up along the rod and the collar can be fitted in the socket at the bottom surface of the spinneret. The baffle can be completely detached from the spinneret by unscrewing the locator disc from the socket at the bottom surface of the spinneret. Instead of thread fit between the tongue and the groove in the case of the baffle of Fig 3 and the collar and the socket in the case of the baffle of Fig 4, the baffle can be push or press fitted or snap fitted in the spinneret.
According to the invention, the quality and uniformity of the filament yarns are substantially increased besides the winding speed or productivity as exemplified by the following non-limiting comparative Examples :
Evenness of the melt spun filament thickness (linear density) on various length scales were measured in the following Examples using the uster tester apparatus (model Uster Tester 4 - CX of Uster Technologies, Switzerland) as uster (overall mass variation in % from mean mass, based on normal cut-length of 1 cm) and uster half inert (medium term irregularity of mass, based on cut-length of 6.4 m at speed of 400 m/min) values. Dynamic shrinkage force (Draw tension, DT) of the partially oriented yarn (POY) yarn was measured on (Lenzing Model DTI 400) using ASTM method No. D 5344. Break elongation and tenacity were determined on a table model Statimat M (TexTechno), using gage length 150 mm, and elongation rate 600 mm/min. Variation from average value

was calculated as CV (coefficient of variation)%. The number of broken filaments during texturing that may be tolerated in practice will depend upon the intended use for the textured yarn and eventual fabric. In practice, in the trade, the ends of the bobbin are examined for broken filaments, and the number of protruding broken filaments is counted so as to give a measure of the probable number of broken filaments in the yarn of that package The total number of these broken filaments (BF) counted is then divided by the number of kg in the package and expressed as BF. On-line Tension sensor (OLT) was used to determine the yarn line tension during texturing. The post twist unit tension (T2) was measured online using the Unitens , (Brochure Tex 303e /5-4, Studio 45 / Koch of Barmag Oerllikon Saurer) and floating mean value, peak detection and CV% were computed. It is desirable to have T2 relatively free of peaks during the texturing of POY (Partially Oriented Yarn) bobbin, and it is characterized in terms of T2 tension variation (CV%) and presence of peaks. OLT rejects refers to the % of bobbins for which during texturing the T2 tension limits (+/- 2 cN) are exceeded. OLT sensors were also used to detect yarn break during texturing. Body breaks refer to number of yarn breakage during texturing of each tonne of yarn. Splice fail refers to failure of joining yarn while transferring from one POY bobbin to another.
Example 1
Polyethylene terephthalate of intrinsic viscosity 0.605 dL/g (phenol-tetrachloroethane solvent, 60:40 wt ratio, 30°C, 0.5 g/cc, as per ASTM D 4603-03) was extruded at 288°C through the spinneret containing 48 holes of diameter 0.36 mm arranged equidistantly in a single circle of diameter 85 mm. The filaments were passed through a quench apparatus comprising a cylindrical cooling chamber formed of a

foraminous section of 10 screens (alternating 100 mesh and 50 mesh) of inside diameter 95 mm and length 190 mm. The non-foraminous section of the cooling chamber had a length of 160 mm. Spin block and blind provided quench delays of 20 mm and 30 mm respectively. The filaments were cooled in the foraminous section with quench air applied through the foraminous section in an outside-in manner at diffuser pressure of 80 Pa. The filament yarns exiting from the cooling chamber was passed through a finish application system and then to a take up device at a winding speed of 3155 m/min. The test results were as shown in the following Table 1.
Example 2
Polymeric filaments were extruded and quenched in a quench apparatus as described in Example 1 including a conical baffle extending centrally along the length of the cooling chamber. The baffle had a top diameter of 50 mm and length of 300 mm. The test results at a winding speed of 3155 m/min were as shown in the following Table 1.
Example 3
Polymeric filaments were extruded and quenched in a quench apparatus as described in Example 1 including a constricted tube provided centrally at the exit of the foraminous section. The constricted tube had an inner diameter of 28 mm and length of 425 mm. The constricted tube had a convergent section at its inlet end with an outer end diameter of 94.5 mm and a divergent section as its outlet end with an outer end diameter of 63 mm. The cooling gas diffuser pressure outside the foraminous section of the cooling chamber was 800 Pa. The test results at winding speeds of 4300 m/min and 4420 m/min were as shown in the following Table 1.

Example 4
Polymeric filaments were extruded and quenched in a quench apparatus as described in Example 1 including a baffle described in Example 2 and a constricted tube described in Example 3. The cooling gas diffuser pressure outside the foraminous section of the cooling chamber was 800 Pa. The test results at winding speeds of 4300 m/min and 4420 m/min were as shown in the following Table 1.
Table 1

Example 1 Example 2 Example 3 Example 4
WindingSpeed(m/min) 3155 3155 4300 4420 4300 4420
Filament characteristics
DT(g) 89 88.2 87.6 101.6 74 87.4
Uster 0.85 0.73 0.93 0.98 0.93 0.97
Half Inert 0.54 0.20 0.39 0.36 0.11 0.12
In Examples 1 to 4, the polymer throughout was adjusted to obtain yarns of 250 denier. In Examples 1 and 2, the filament characteristics deteriorated on increasing the winding speed above 3155 m/min.

It is quite evident in the comparative study in Table 1 that the DT and half inert of the filament yarns obtained by Example 4 were considerably reduced as compared to Example 3 at the same high winding speeds of 4300 m/min and 4420 m/min. Half inert of filament yarns obtained by Example 4 were also considerably reduced at high winding speeds of 4300 m/min and 4420 m/min as compared to Example 2 employing lower speed of 3155 m/min. DT of Example 4 at 4420 m/min was lesser or almost the same as that of Example 2. The reduced half inert of filament yarns of Example 4 indicates that the medium range uniformity of the yarns is increased. The low half inert and comparable uster also indicate the improved denier of the yarn. In addition, the reduced DT value at 4300 m/min indicates that the yarn produced can be drawn to a larger extent during the subsequent steps such as texturing or draw-twisting so as to give increased productivity of the subsequent process. If, however, this possibility (increasing winding speed and productivity) is not utilized during such melt spinning, the lower DT of the melt spun filaments allows an increased productivity during the subsequent drawing process. According to the invention, there is thus achieved increased fiber uniformity with increased productivity by way of increased winding speed during melt spinning. The overall improvements in the product characteristics in terms of Half inert, uster and DT with increased productivity as obtained in Example 4 clearly establish the synergy or combined effect and functional cooperation of the component parts of the quench apparatus of the invention, especially the baffle and constricted tube combination. This is undoubtedly a new finding and technical advance in melt spinning technology. Continuous polymeric filament yarns having such enhanced fiber uniformity especially low half inert upto 0.15 with increased productivity are considered to be novel.

Example 5
The filament samples made as in Example 3 (winding speed 4300 m/min) and Example 4 (winding speed 4420 m/min) were draw textured (draw ratio 1.7) on a Barmag FK6-1000 M Type Pilot machine at 900 m/min for processibility characteristics and physical characteristics of the filaments (T2 tension, OLT rejects, body-breaks, splice fails) as well as for filament breaks and mechanical properties (tenacity and elongation). The test results were as shown in the following Table 2 :
Table 2

Processability characteristics Example 3 Example 4
Unitens T2 (g) 52 51.5
Individual position CV% mean 1.1 0.8
Peaks in tension during process Repeated tension peaks observed on certain polyester yarn spools No tension peaks observed on the polyester yarn spools
OLT REJECTION 10% Nil
Body Breaks / ton 26 Nil
Total Breaks / ton (splice fail+body) 69 Nil
% of spools containing no broken filaments (> 2 mm ) Nil 63
Broken filaments / kg 0.71 0.08
Elongation % 23 23
Elongation CV% 0.9 0.3

Tenacity (gpd) 4.5 4.4
Tenacity CV% 0.15 0.05
Table 2 shows the improved yarn characteristics of Example 4 as compared to those of Example 3. The improved characteristics during texturing indicate the possibility of enhanced uniform dyeing and dimensional stability of the textured product package spool. Table 2 further shows that the yield is increased in the case of filament yarns of Example 4 during the texturing by reducing breaks. Product uniformity is also improved in the case of filaments of Example 4 as indicated by reduced CV of the mechanical properties ie elongation and tenacity. Table 2 is further illustrative of the synergy or combinational effect and technical advance of the quench apparatus of the invention.
Example 6
The procedure of Example 4 was carried out with baffles of different geometries and the test results at winding speed of 4300 m/min and diffuser pressure of 800 Pa were as shown in the following Table 3 :
Table 3

Baffle type Cylinder Truncated-cone Cone
top dia (mm) 27 50 50
length (mm) 200 200 300
Uster 1.15 1.28 0.93
Half Inert 0.30 0.38 0.11
Truncated-cone bottom diameter was 17 mm.

Table 3 shows that the uster / half inert changed depending upon the baffle geometries. Table 3 also shows that conical baffle gave reduced uster and half inert and is preferable.

We claim:
1. A method for melt spinning of continuous polymeric filament yarns having enhanced fiber uniformity with increased productivity, the method comprising :
i) extruding polymeric filaments from a molten polymeric material
through the capillaries in the spinneret;
ii) cooling the filaments in a quench apparatus located underneath the
spinneret and comprising a cooling chamber formed of a foraminous
section and a non-foraminous section and a jacket located around the
cooling chamber in spaced apart relationship therewith to form a plenum
chamber for a cooling gas entering the quench apparatus through a gas
inlet provided with the jacket, cooling of the filaments being carried out
by passing the filaments through the foraminous section over an oblong
baffle extending from the bottom surface of the spinneret centrally along
the cooling chamber and allowing the cooling gas to flow onto the
filaments, the baffle directing the cooling gas downward to quench the
filaments by concurrent flow of the cooling gas, the baffle extending
from the bottom surface of the spinneret at least upto 40% of the cooling
chamber describing a clearance with the capillaries in the spinneret;
iii) subjecting the filaments exiting the foraminous section to
delayed cooling by accelerating the cooling gas at the exit of the foraminous section by passing the cooling gas and the filaments through a constricted tube of reduced dimensions provided centrally at the exit of the foraminous section, the constricted tube having a convergent section at its inlet end and optionally a divergent section at its outlet end; and
iv) winding the filament yarns exiting the constricted tube on a
winding device at a winding speed of at least 3000 m/min.

2. The method as claimed in claim 1, wherein the extrusion of
the polymeric filaments is carried out in a spinneret having the capillaries
in a circle or in a plurality of concentric circles and the cooling of the
filaments is carried by passing the filaments over a baffle having a top
surface area of 20 to 80% of the bottom surface area of the spinneret
within the circle of capillaries in the spinneret or inner or innermost
circle of capillaries in the spinneret and a bottom surface area of 0 to
80% of the bottom surface area of the spinneret within the circle of
capillaries in the spinneret or inner or innermost circle of capillaries in the
spinneret.
3. The method as claimed in claim 1 or 2, which is carried out at a winding speed >3500 m/min.
4. The method as claimed in claim 1 or 2, which is carried out at a winding speed >4000 m/min.

5. The method as claimed in anyone of claims 1 to 4, wherein the cooling gas is allowed to flow into the foraminous section in an outside-in manner.
6. Continuous polymeric filament yarns having enhanced fiber uniformity with increased productivity.
7. Continuous polymeric filament yarns having enhanced fiber
uniformity including reduced half inert upto 0.15 with increased
productivity.

8. A quench apparatus for use in the melt spinning of continuous
polymeric filament yarns having enhanced fiber uniformity with
increased productivity from a molten polymeric material through the
capillaries of the spinneret, the quench apparatus being located
underneath the spinneret and comprising a cooling chamber formed of a
foraminous section and a non-foraminous section, a jacket provided
around the cooling chamber in spaced apart relationship therewith to form
a plenum chamber for a cooling gas entering the quench apparatus
through a gas inlet provided with the jacket, an oblong baffle extending
from the bottom surface of the spinneret centrally along the cooling
chamber so as to direct the cooling gas downward to quench the filaments
by concurrent flow of the cooling gas, the baffle extending from the
bottom surface of the spinneret at least upto 40% of the cooling chamber
describing a clearance with the capillaries in the spinneret and a
constricted tube of reduced dimensions provided centrally at the exit of
the foraminous section for exiting the cooling gas and filaments, the
constricted tube having a convergent section at its inlet end and
optionally a divergent section at its outlet end, the constricted tube
accelerating the cooling gas at the exit of the foraminous section so as to
delay the cooling of the filaments exiting the foraminous section.
9. The quench apparatus as claimed in claim 8, wherein the
spinneret comprises capillaries provided in a circle or in a plurality of
concentric circles and the baffle has a top surface area of 20 to 80% of
the bottom surface area of the spinneret within the circle of capillaries
in the spinneret or inner or innermost circle of capillaries in the spinneret
and a bottom surface area of 0 to 80% of the bottom surface area of the
spinneret within the circle of capillaries in the spinneret or inner or
innermost circle of capillaries in the spinneret.

10. The quench apparatus as claimed in claim 8 or 9, which is used for melt spinning of continuous polymeric filament yarns at a winding speed >3500 m/min.
11. The quench apparatus as claimed in claim 8 or 9, which is used for melt spinning of continuous polymeric filament yarns at a winding speed >4000 m/min.
12. The quench apparatus as claimed in anyone of claims 8 to 11,
wherein the baffle is solid, porous or hollow and is conical shaped,
conical shaped with a concave or convex outer surface, partly cylindrical
and partly conical or partly cylindrical and partly conical with a concave
or convex outer surface.
13. The quench apparatus as claimed in anyone of claims 8 to 12 which is configured to allow outside-in flow of the cooling gas into the foraminous section.
14. The quench apparatus as claimed in anyone of claims 8 to 13, wherein the baffle is detachably fitted at the bottom surface of the spinneret.
15. The quench apparatus as claimed in claim 14, wherein the
baffle is provided with an externally threaded tongue at its top end and
the spinneret is provided with a corresponding groove at its bottom
surface, the groove having threads on the sidewall thereof matching with
the threads on the tongue, the baffle being detachably fitted at the
bottom surface of the spinneret by locating the tongue at the top end

thereof in the groove at the bottom surface of the spinneret in thread engagement therewith.
16. The quench apparatus as claimed in claim 14, wherein the
baffle is provided with an oblong slot one end of which is closed and the
other end of which is extending upto the top end of the baffle, a collar
provided at the top end of the baffle and formed with a through hole in
alignment with the oblong slot, the collar being externally threaded, the
spinneret is provided with a socket at its bottom surface corresponding to
the collar, the sidewall of the socket being threaded corresponding to the
threading on the collar, a rod engaged in the through hole in the collar,
one end of the rod extending into the oblong slot through the through
hole in the collar and provided with a stopper adapted to abut against the
bottom end of the collar and the other end of the rod being provided
with a locator disc having threads on the outer circumference thereof
corresponding to the threading at the sidewall of the socket, the collar
with the baffle being slidably held over the rod, the locator disc being
adapted to be detachably located in the socket in thread engagement
therewith and the collar being adapted to be detachably fitted in the
socket in thread engagement therewith below the locator disc.
17. The quench apparatus as claimed in anyone of claims 8 to 16,
wherein the baffle extends upto 40 to 100% of the cooling chamber or
into the constricted tube partly.

ABSTRACT
A method and quench apparatus (1) for melt spinning of continuous
polymeric filament yarns having enhanced fiber uniformity with
increased productivity. Polymeric filaments (15) are extruded from a
molten polymeric material (not shown) through the capillaries (not
shown) in the spinneret (2). The filaments are cooled in the quench
apparatus located underneath the spinneret and comprising a cooling
chamber (6) formed of a foraminous section (7a) and a non-foraminous
section (7b) and a jacket (8) located around the cooling chamber in
spaced apart relationship therewith to form a plenum chamber (9) for a
cooling gas (not shown) entering the quench apparatus through a gas
inlet (10) provided with the jacket. The filaments pass through the
foraminous section over an oblong baffle (11) extending from the bottom
surface of the spinneret centrally along the cooling chamber and a
cooling gas is allowed to flow onto the filaments. The baffle directs the
cooling gas downward to quench the filaments by concurrent flow of the
cooling gas. The baffle extends from the bottom surface of the spinneret
at least upto 40% of the cooling chamber describing a clearance with the
capillaries in the spinneret. The filaments exiting the foraminous
section are subjected to delayed cooling by accelerating the cooling gas
at the exit of the foraminous section by passing the cooling gas and the
filaments through a constricted tube (12) of reduced dimensions provided
centrally at the exit of the foraminous section. The constricted tube has
a convergent section (13) at its inlet end and optionally a divergent
section (14) at its outlet end. The filament yarns exiting the constricted
tube are wound on a winding device at a winding speed of at least 3000
m/min(Fig 1).

METHOD AND QUENCH APPARATUS FOR MELT SPINNING OF CONTINUOUS POLYMERIC FILAMENT YARNS

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