MXPA01001012A - Method and apparatus for quenching of nonwoven filaments - Google Patents

Abstract

A method and apparatus for improved quenching of nonwoven filaments utilizing a turbulence inducing bar arrangement disposed in a stream of quenching gas between the quenching gas supply apparatus and the group of filaments being extruded. The bar arrangement increases the turbulence of the quenching gas so that the gas applied to the filament group has a turbulence intensity of at least about 5%. The turbulent quenching gas penetrates the interior of the filament bundle to provide more efficient removal of heat.

Description

METHOD AND APPARATUS FOR IMPROVED COOLING OF NON-WOVEN FILAMENTS FIELD OF THE INVENTION This invention is directed to a method and apparatus for improving the cooling efficiency of non-woven filaments after they are extruded from a spinning organ. More specifically, the invention is directed to a method and apparatus for inducing turbulence within air streams used to cool the filaments, thereby improving the cooling efficiency of the air.

BACKGROUND OF THE INVENTION The cooling of nonwoven filaments using air and other fluids is known in the art. U.S. Patent No. 3,070,839 issued to Thompson, describes using the air stream to cool the filaments fused with yarn. A grid is placed in the air supply of the filaments to diffuse the air stream and minimize its turbulence. Cooling is achieved in areas ranging from a relatively low air flow near the spinner organ to successively larger air flows at distances away from the spinner. This technique * & amp; & It allegedly reduces the breaking of the filaments during cooling.

U.S. Patent No. 4,492,557 issued to Ray et al. Describes the use of diffusers to reduce the turbulence of the cooling gas. The described turbulence reduction diffusers include grids, porous foam, perforated metal plates, metallic wool, sintered metal, felts and grids with mesh grids. A varied gas distribution pattern can be achieved by providing a diffuser having regions of different porosity.

U.S. Patent No. 4,712,988 issued to Broaddus et al., Discloses an apparatus for radially cooling the melted filaments with spinning. A cooling chamber is provided with a perforated distribution cylinder between the filaments and the gas supply. The cooling gas enters the cylinder from all; the sides and diffuses by the perforated cylinder. The perforated openings are sized to control the speed of the cooling gas entering the filaments.

The use of flow control devices, such as gas diffusers, has generally been for the purpose of reducing gas velocity and turbulence. These techniques distribute and diffuse the gas flow and try to introduce a quieter laminar flow that has less tendency to disturb or break the filaments. However, the nature of the laminar flow is such that when the cooling gas (for example air) makes contact with the filaments, the heat transfer and cooling cups are relatively lower. There is a need or desire in the non-woven industry for a cooling technique which optimizes the cooling efficiency as well as the even distribution of the gas.

SYNTHESIS OF THE INVENTION The present invention is directed to a method and apparatus which improves the cooling efficiency of the non-woven filaments that come out of a spinning organ, compared to the prior art techniques. The method and apparatus increase the turbulence of a cooling gas stream in a controlled manner, such as to increase the heat transfer rate without unduly disturbing or breaking the filaments. This is in contrast to prior art techniques which distribute the gas stream at reduced turbulence levels. The turbulent gas flow distributed better to the cooling by achieving a better heat transfer between the filaments and the gas, and a better penetration of the groups of filaments and bunches by the gas flow, so that the inner layers of filaments are reached more easily and quickly by gas.

According to the invention, a turbulence-inducing rod array is placed in the cooling gas stream on the side of a spinning organ used to extrude non-woven polymer filaments, and can be placed downwards of devices typically used to evenly distribute the gas flow. The bar array may include a plurality of essentially spaced parallel bars, for example, or may involve another array. The cooling gas is directed through the turbulence-inducing rod array towards the sunken filaments leaving the spinning organ. By passing the cooling gas stream through the bar array, it is divided into a plurality of smaller streams which interfere with each other to cause turbulence.

The bar arrangement that induces turbulence operates to distribute the cooling gas along the filaments as well as to cause turbulence. In order for turbulence to occur, the cooling gas needs only to be supplied to a conventional flow rate and at a conventional flow rate. The bar arrangement causes turbulence without requiring increasing the flow rate, thus minimizing the disruption or breaking of the filaments being cooled. One goal is to achieve as much gas penetration of the filament group as possible without damaging the filaments.

With the foregoing in mind, it is a feature and an advantage of the invention to provide an efficient method for cooling a bundle or group of filaments using a distributed stream or streams of turbulent cooling gas.

It is also a feature and an advantage of the invention to provide an apparatus which increases the turbulence of the cooling gas to cause a more efficient cooling of a group or bundle of filaments that are being extruded from a spinning organ.

The foregoing and other features and advantages will be more apparent from the following detailed description of the currently preferred embodiments, read in conjunction with the accompanying drawings. The detailed description of the drawings are intended to be illustrated rather than to limit the scope of the invention which is being defined by the appended claims and the equivalents thereof.

BRIEF DESCRIPTION OF THE DRAWINGS Figure 1 illustrates a turbulence induction rod arrangement used in the method and apparatus of the invention.

Figure 2 schematically illustrates how the turbulence-inducing bar array converts one or more streams of laminar gas flow into turbulent streams by dividing the initial stream or streams into smaller streams which interfere and collide with each other.

Figure 3 schematically illustrates a dual-partition plate arrangement used to make non-woven filaments, including an interior and exterior gas cooling system, with turbulence inducing bar arrays incorporated in the exterior gas cooling system; Figures 4 (a) and 4 (b) illustrate turbulence data generated for examples 1-4 described below: Fig. 5 is a diagram of IR heat signature data for examples 1-4; Y H¡fe &rf «? 'S" < i * - j -, ^ _ fC m f m' i f.

Figure 6 is a schematic of one denier per filament generated for examples 1-4.

DEFINITIONS As used herein, the term "nonwoven fabric or fabric" means a fabric having a structure of individual fibers or threads which are in between, but not in an identifiable manner as in a woven fabric. Fabrics or non-woven fabrics have been formed from many processes such as, for example, meltblowing processes, spin-bonding processes, and carded and bonded tissue processes. The basis weight of the non-woven fabrics is usually expressed-; in ounces of material per square yard (osy) or grams per square meter (gsm) and useful fiber diameters are usually expressed in microns (note that to convert from ounces per square yard to grams per square meter multiply ounces per square yard by 33.91).

As used herein, the term "microfibers" means small diameter fibers having an average diameter no greater than about 75 microns, for example, having an average diameter of from about 5 microns to about 50 microns, or more particularly, microfibers can have an average diameter of from about 10 microns to about 20 microns. Another frequently used expression of fiber diameter is denier, which is defined as grams per 9 thousand meters of a fiber * and can be calculated as a fiber diameter in square microns, multiplied by the density in grams / cubic centimeter, multiplied by 0.00707. A lower denier indicates a finer fiber and a higher denier indicates a thicker or heavier fiber. For example, the diameter of a polypropylene fiber given as 15 microns can be converted to denier by placing the square, multiply the result by .89 grams per cubic centimeter and multiplying by 0.00707. Therefore, a polypropylene fiber of 15 microns has a denier of about 1.42 (152 x 0.89 x .00707 = 1.415). Outside the United States of America, the unit of measurement is most commonly the "tex" which is defined as grams per kilometer of fiber. The tex can be calculated as denier / 9.

As used herein, the term "spunbonded fibers" refers to fibers of small diameter which are formed by extruding the molten thermoplastic material as filaments from a plurality of finely circular, usually capillary vessels of a spinner member with the diameter of the extruded filaments then being rapidly reduced as, for example, indicated in US Pat. Nos. 4,340,563 issued to Appel et al .; and 3,692,618 granted to Dorshner and others, 3,802,817 granted to Matsuki and others, 3,338,992 and 3,341,394 granted to Kinney, 3,50-2,763 granted to Hartman, 3,502,538 granted to Petersen, and 3,542,615 granted to Dobo and others, each of which is incorporated herein in its entirety by reference. The yarn-linked fioras are generally non-sticky on the surface when they enter the pulling unit, or when they are deposited on a collecting surface. The yarn bonded fibers are cooled and generally continuous and have average diameters greater than about 7 microns, more particularly, between about 10 and 20 microns.

As used herein the term "polymer" generally includes but is not limited to, homopolymers, copolymers, such as, for example, block, graft, random and alternating copolymers, terpolymers, etc., and mixtures and modifications thereof. In addition, unless specifically limited otherwise, the term "polymers" will include all possible geometric configurations of the material. These configurations include, but are not limited to isotactic, syndiotactic and random symmetries, and include crystalline polymers as well as semicrystalline polymers, homorphic polymers and waxes.

As used herein the term "monocomponent fiber" refers to a fiber formed from one or more extruders that use only one polymer. This does not mean that fibers formed from a polymer to which small amounts of color additive, antistatic properties, lubrication, hydrophilicity, etc. have been extruded are extruded. These additives, for example, titanium dioxide for color, are generally present in an amount of less than 5% by weight and more typically of about 2% by weight.

As used herein, the term "conjugated fibers" refers to fibers which have been formed from at least two extruded polymers of separate extruders but which have been spun together to form a fiber. Conjugated fibers are also sometimes referred to as multicomponent or bicomponent fibers. The polymers are usually different from one another even though the conjugated fibers can be monocomponent fibers. The polymers are arranged in distinct zones placed essentially constant across the cross section of the conjugated fibers and extend continuously along the length of the conjugate fibers. The configuration of such conjugated fibers can be, for example, a sheath / core arrangement A where one polymer is surrounded by another or can be a side-by-side arrangement or an arrangement of "islands in the sea". Conjugated fibers are taught in the patents of the United States of America Nos. 5,108,820 granted to Kaneko and others, 5,336,552 granted to St crack and others, and 5,382,400 granted to Pike and others, each of which is incorporated herein in its entirety by reference. For the Two-component fibers, polymers may be present? Yes, in proportions of 75/25, -and S0 / 50, 25/75 or any other desired proportions.

As used herein, the term "biconstituent fibers" refers to fibers which have been formed from at least two extruded polymers from the same extruder as a mixture. The term "mixture" is defined below. The biconstituent fibers do not have the various polymer components arranged in different zones placed relatively constant across the cross-sectional area of the fiber and the various polymers are usually not continuous along the entire length of the fiber, instead of this they form fibrils or protofibrils which start and end at random. Biconstituent fibers are sometimes referred to as multi-constituent fibers. Fibers of this general type are discussed in, for example, U.S. Patent No. 5,108,827 issued to Gessner. Bicomponent and biconstituent fibers are also discussed in the textbook "Polymer Compounds and Mixtures" by Johi A. Manson and Leslie H, Sperling, copyright 1978 by Plenum Press, a division of Plenum Publishing Corporation of New York, IBSN 0-306-30831-2, to pages 273 to 277..

As used herein, the term "mixtures" as applied to polymers means a mixture of two or more polymers while the term "alloy" means a subclass of mixtures wherein the components are immiscible but have been compatibilized. The "miscibility" and the "immiscibility" are defined as mixtures that have negative and positive values, respectively for the free energy of mixing. In addition, "compatibilization" is defined as the process of modifying the interfacial properties of an immiscible polymer mixture in order to make an alloy.

As used herein, the term "heteroconstituent nonwoven fabric" (or woven layer) refers to a nonwoven layer or fabric having a blend of at least two filament types or fiber A and B which differ from one another. others in terms of polymer contents, fiber size ranges, fiber shapes, pigment or additive fillers, ripple levels, and / or other compositional and physical properties.

As used herein, the term "multilayer nonwoven fabric" refers to a nonwoven fabric having at least two types of filament or fiber arranged in two or more different layers. The filaments or fibers in the different layers may differ from each other in terms of overall polymer contents, fiber size ranges, fiber shapes, additive pigment fillers, ripple levels and / or other properties. of composition and physics. Individual layers in a multilayer nonwoven fabric require, but do not need to be, heteroconstituent nonwoven fabric layers as described above.

As used herein, the term "turbulence-inducing rod arrangement" refers to an array of rods which are sufficiently large, and sufficiently separated to cause a wake-induced increase in the turbulence of a gas which passes between the rods. bars. A more detailed description is provided below. The bars are larger and are more separated than the elements in the mesh grids and similar devices which reduce the turbulence instead of increasing it.

DETAILED DESCRIPTION OF CURRENTLY PREFERRED INCORPORATIONS In order to achieve a well-distributed and uniform gas stream, the gas used to cool the non-woven filaments is typically passed through the perforated plates and grids and through a honeycomb. These devices employ narrow mesh openings to generate the flow having a low turbulence intensity, often in the order of 2-3% for typical flow rates of cooling applications. Gas having such an intensity of turbulence provides an inefficient and poor convective heat transfer, which is the primary mechanism of heat transfer between the non-woven filaments and the cooling gas. For example, gas that has healthy low turbulence does not penetrate sufficiently into a group or bundle of molten filaments to carry heat away from the inner filaments in the group or bundle.

The present invention provides an apparatus and method which can be used to increase the turbulence of the cooling air, at a conventional speed, which has been distributed evenly by the conventional apparatus described above. Referring to Figure 1, a turbulence-induced bar array 10 includes a plurality of bars 12 supported by two side bars 14. The bars 12 are separated from each other by open spaces 16. Bars 12 are preferably and essentially parallel to each other. another, and are preferably placed essentially perpendicular to the direction of travel of the non-woven filaments that are being cooled.

The planar area occupied by the bar array 110 can be defined as including the flat area occupied by the bars 12 plus the flat areas occupied by the open spaces 16 between the bars, and not including the area occupied by the support bars 14. The bars 12 should occupy about: 20-80% of the planar area occupied by the array of bars 10, preferably around 30-70% of the flat area occupied by the bar arrangement 10, more preferably around 40-60% of the planar area occupied by the bar array 10. Similarly, the open spaces 16 should occupy about 20-80% of the flat area occupied by the bar array 10 , preferably around 30-70%, more preferably around 40-60% If the percentage area occupied by the bars 12 is very low, the rod arrangement 10 will have little or no effect to convert the gas supply flow (for example air) to turbulent laminar. If the percentage of area occupied by the bars 12 is very large, leaving the open spaces 16 very small, the array of bars 10 can behave like diffusing grids of the prior art which reduces the turbulence instead of increasing it.

The design and spacing of the bars 12 must be such that the cooling gas is converted to turbulent flow having a turbulence intensity of greater than about 5%, preferably greater than about 10%, more preferably greater than about 20% , as measured by the test procedure described below. The operation generated] of the rods 12 are shown schematically in Figure 2. The parallel arrows illustrate the essentially laminar gas flow from one source to the rods 12. The semicircular apex shaped arrows represent wakes illustrative of a more turbulent flow of Cooling gas, after the flow passed through the bars. Interference of the bars 12 in the flow path causes the cooling gas to pass through the openings 16, and divide the flow into a plurality of smaller streams. The smaller currents are directed downward at a higher average velocity from the bars than the main gas stream approaching the bars. The smaller currents are also directed at different angles, which result in multiple wake formation down the bars. This formation of multiple stelae causes the global flow to become much more turbulent.

The size of the bars 12 must be large enough to divide and redirect the flow of cooling gas in the manner shown in Figure 2 as to cause sustained turbulence. If the bars 12 are very small, they will behave like a mesh grid, either reducing or failing to significantly increase turbulence. The bars 12 can have an average diameter of about 0.125-1.00 inches, preferably around 0.25-0.75 inches, more preferably around 0.40-0.60 inches. Similarly, the openings 16 between the bars may have an average width of about 0.125-1.00 inches, preferably about 0.25-0.75 inches, more preferably about 0.40-0.60 inches. The bars 12 (and the global bar arrangement 10) can be constructed of metal wood, rigid plastic, other materials, which have a . • Hjah * adequate structural integrity and combinations of the above materials.

The number and length of bars 12 in the bar array that induces turbulence 10 will vary depending on the dimensions of the source of cooling gas whose flow is being modified, and of the bundle of filaments to which the modified flow is being directed. The array of bars 10 must be dimensioned to interfere with essentially all of the cooling gas which flows from the gas source to the bundle of filaments. If the bar arrangement 10 is placed with the bars essentially perpendicular to the filaments, then the length of the bars 12 must be at least as large as the bundle of filaments.

The length of the bar array 10 can be defined as the dimension perpendicular to the length of the individual bars 12. The length of the bar array 10 should be at least as large as the length of the gas flow source. The length of the gas flow source is the length of the part or parts of any apparatus which emits the cooling gas. The number of bars 12 in the array 10 can vary from about 6-50 bars 12 by foot length of bar arrangement 10, preferably around 8-25 bars 12 by foot length of a 10-bar array, more preferably about 10.15 bars 12 per foot length and bar arrangement 10.

Referring to Figure 3, an apparatus for extruding and cooling non-woven filaments in a non-woven fabric of heteropolymers and / or multilayers using the turbulent cooling gas is schematically illustrated. The dual spin pack 100A and 100B are arranged on opposite sides of a central duct 112. A first bunch 120 of filaments is extruded from the spin pack 100A. A second bunch 122 of filaments, which may be the same or different from the first bunch 120, is extruded from the second spin pack 100B. The filament bundles 120 and 122 are cooled and collected at the entrance of the pulling unit 230.

The first bundle of filaments 120 is cooled from the outside using the air supplied from the cooling air supply zones 140, 141, 142 and 143, the surfaces of which may have conventional honeycomb configurations. According to the invention, a first turbulence induction bar arrangement 10 is provided with the cooling air supply zones 140, 142, 142 and 143 and the bundle of filaments 120. The arrangement of bars 10 divides the air from cooling in several interference currents to cause turbulence, as illustrated by the arrows in Figure 2. The array of bars 10 is preferably placed on its bars perpendicular to the displacement of the first bundle 120.

The array of rods 10 should be as close as possible to the bundle of filaments 120 but not so close as to result in a contact, so that the turbulent air flow generated by the array 10 is sustained while contact is made and penetrates the bundle of filaments 120. The array of bars 10 should be located at about 0.5-2.0 inches from the bundle of filaments 120, preferably at about 0.5-1.0 inches more preferably at about 0.5 inches. If the filament handling 120 arches inwardly as shown, it may be impractical to evenly space the array of rods 10 of the bunch of filaments 120. In this case, the distance between the array of rods 10 / the bundle of filaments 120 must be determined and controlled at the end of the bundle of filaments closest to the package; of spinning, which is where the initial cooling occurs. Frequently, the distance is limited since the nearest part of the bunch of filaments 120 can only be about 3.0-4.0 inches from the honeycomb surface which supplies the cooling gas.

The flow velocity of the cooling gas or air from the supply zones 140-143 must be conventional. Generally, the flow velocity of the supply gass should vary from about 50-500 feet per minute, preferably from about 100-400 feet per minute, more preferably from about 200-300 feet per minute, the air temperature Cooling can also be controlled to determine the desired filament properties. For filaments bonded with polypropylene yarn, the cooling air may vary from about 5-25 ° C, as for example.

The second bundle of filament 122 is cooled from the outside using the air supplied from the cooling air supply zones 144, 145, 146 and 147. A second turbulence inductor bar array 10 is provided between the air supply zones of cooling 144, 145, 146 and 147, and the bundle of filaments 122. The distances, the air flow rates, and the temperatures given above are equally applicable to the second group of cooling air supply zones, the second arrangement of bar and the second bundle of filaments 122.

As shown, the yarn packages 100A and 100B can be arranged on opposite sides of the conduit 112. Additional cooling air can be supplied through the conduit 112, down between the 100-side plates in a single stream (or zones). ) to help cool the inner side of the filament bundles 120 and 122. The conduit 112 can advantageously be divided by the divider 114 in the supply zone 116 and 118 which direct the cooling fluid through the bundles 120 and 122 respectively. The perforated plates 124, 126 may be provided to control the flow of fluid and increase its uniformity. Optionally, turbulence inducing bar arrangements can be provided between duct 112 and bunches; of filaments 120 and 122 to increase the turbulence of the indoor cooling air as well. The smoke exhaust ducts 128 and 130 are placed on opposite sides of the bunches 120 and 122 to receive a portion of the cooling fluid. The rest of the cooling fluid is pulled into the filament bundles and carried or carried by them to the fiber pull zone 230.

Spin packs 100A and 100B can be used to extrude non-woven filaments of any kind including without limitation spunbond filaments, meltblown filaments (e.g. microfibers), and combinations thereof. The filaments of the two packages of yarns may be the same or of a different type, and the composition itself or different. Suitable polymers for use in the filaments include, without limitation, polyethylene, polypropylene, polyamides, polyesters, ethylene and propylene copolymers, copolymers of ethylene or propylene with an alpha-olefin C ^ -C ^, terpolymers of ethylene ^ L > , • with propylene and alpha-olefin the ethylene vinyl acetate copolymers, the propylene vinyl acetate copolymers, the styrene-poly (ethylene-alpha-olefin) elastomers, the polyurethanes, the AB block copolymers wherein A is formed from poly (vinyl arene) moieties such as polystyrene and B is a middle elastomeric block such as a conjugated diene or a lower alkene, polyethers, polyether esters, polyacrylates, ethylene alkyl alkylates, polyisobutylene, polybutadiene, isobutylene-isoprene copolymers and combinations of any of the above. The filaments may be monocomponent, conjugated, bicomponent or mixtures of the polymers.

The groups of filaments 120 and 122 may also be bicomponent filament varieties, or a combination of monocomponent and bicomponent filaments. The different varieties of the bicomponent filaments include those polymeric filaments that have at least two distinct components, commonly known in the art as "sheath-core" filaments, "side by side" filaments and "islands in the sea" filaments. . Filaments containing 3 or more different polymer components are also included. Such filaments are generally linked with spinning, but can be cast using other processes. The monocomponent filaments, by comparison, include only one polymer.

The filament groups 120 and 122 can be spun bonded, melt blown, or a combination thereof. Spunbond filaments are essentially continuous and generally have average fiber diameters of about 12-55 microns, often about 15-25 microns. The meltblown microfibers are generally discontinuous and have average fiber diameters of up to about 10 microns, preferably about 2-6 microns.

The nonwoven filaments may be crimped or uncurled. Curled filaments are described, for example, in United States Patent No. 3,341,394 issued to Kinney. The curled filaments may have less than 30 crimps per inch, or between 30-100 crimps per inch, or more than 100 crimps per inch. For example, type A and type B filaments may differ in terms of their ripple levels, or as to whether ripple is present.

It is also possible to have other materials mixed with the polymer used to produce a nonwoven fabric according to this invention as the fluorocarbon chemicals to improve the chemical repellency which may be, for example, any of those taught in the patent of United States of America No. 5,178,931, fire retardants to increase fire resistance and / or pigments to give each layer the same or different colors. Five retarders and pigments for the melt-blown and spin-linked thermoplastic Leos polymers are known in the art and are often internal additives.

A pigment, if used, is generally present in an amount of less than 5% by weight of the layer while other materials may be present in a cumulative amount of less than 25% by weight.

An additional advantage of the turbulent cooling air is that it improves cooling efficiency by allowing the air to penetrate the bundle of filaments and to remove the heat from the interior., instead of resting only on the transfer of heat to the other layer or curtain of bunches of filaments, with which the cooling air first makes contact. The invention is not limited to the dual spin package arrangement, but is applicable to any number of spin packets. The following examples illustrate the increase in turbulence caused by the turbulence inducer bar arrangement in a single spin pack apparatus. - = ---- ^ --- £ fc- - »m *?» & lt - M. < EXAMPLES The following tests were carried out to evaluate the turbulence inducing operation of an array of bars constructed of parallel wooden bars against two other structures. In each case, the structure was placed between an air supply source and a bundle of filaments that is being cooled. The evaluated structures were as follows.

EXAMPLE 1 For example 1, a turbulence enhancement structure was not installed between the cooling air supply and the filament bundle.

EXAMPLE 2 For example 2, a large dent grid was used that had 74.8% open air and included a mesh opening per linear inch. The wire diameter was 0.135 inches.

EXAMPLE 3 For example 3, a much smaller mesh grid that has 57.8% open air and includes 2 mesh openings per linear inch was used. The wire diameter 'was 0.120 inches.

EXAMPLE 4 For example 4, a horizontal arrangement of wood blocks, configured as shown in figure 1, was used. The bars were 0.625 inches in diameter and were spaced 1.25 inches apart at their centers. The open area was 50%.

A single spin pack was operated at standard conditions. The fibers were spun from a mixture of 98% by weight of polyopropylene and 2% by weight of titanium dioxide. Fiber deniers ranged from about 1.8-22.2 deniers per filament. The temperature of the spin pack was set to 440 ° F.

The chilled air supply apparatus includes three zones, arranged in sequence. The cooling air velocities were then at about 250 feet per minute for the purpose of comparing turbulence and from 120-180 feet per minute for the purpose of comparing the cooling efficiencies for the structures.

To compare the turbulence induction effect of the structures tested, each turbulence enhancement structure was placed about 2 inches out of the cooling air supply apparatus. There was no extrusion of the polymer through the spinner during the turbulence measurements. Turbulence was measured about 3 inches out from the air supply apparatus (e.g. just downstream of the turbulence enhancement structure) in the first and third cooling zones. For Example 1 (no turbulence improvement structure), the turbulence was measured at about 5 inches from the air supply apparatus. Each cooling zone was 20 inches long (upper and lower) and the turbulence was measured at zero, 7, 14, 21 and 28 inches.

To measure the turbulence, a hot wire anemometer was used. The instrument included a probe, a main designed processing unit that produces an average voltage, and a voltage meter used to supply an RMS (square root mean) voltage. The probe was placed in the proper location in the gas flow, and the mean voltage was measured. The RMS voltage was divided by the mean voltage, and the result was multiplied by 100% to obtain the turbulence intensity percent.

The results for the first and third areas are drawn in Figures 4 (a) and 4 (b). In both zones, the intensity of the turbulence measured without a turbulence enhancing structure (example 1) was very low, at around 1-3%. When either of the two screens was installed (example 2 and 3) the intensity of the turbulence increased somewhat, to around 7-8% for the smaller mesh grid and around 9-15% for the larger mesh grid . When the turbulence improvement bar arrangement of the invention (example 4) was installed, the intensity of the turbulence increased substantially around 18-32%.

To compare the cooling efficiencies of the structures tested, each turbulence improvement structure was placed about 1 inch from the cold air supply apparatus (due to limited space) and polymer filaments were extruded as described above. The flow rates for the cooled air were around 120 feet per minute for the first zone and around 180 feet per minute for the third zone. The cooling of the filaments was measured using two techniques. First an infrared INFRAMETRICS registered brand camera was used to measure the heat profile for each bundle of fibers in **? -ß * - the same region as it passes between the cooling zones. The thermograms were obtained by showing the heat profiles for the constant temperature regions. The camera was operated at a range of 3, in the self-extension mode. The maximum length of the heat profile was measured for each sample and the results were compared. The results of this comparison are shown in Figure 5.

Second, the main filament deniers were measured for the different turbulence enhancing structures. The higher deniers reflect a more effective cooling, since the filament diameters will not stretch as much. The results of this comparison are shown in Figure 6.

Figures 5 and 6 both illustrate the array of bars (example 4) achieving a better cooling of the filament bundles than that of the mesh structures (examples 2 and 3) of the control without a turbulence by increasing the structure (example 1). The results illustrate that the turbulence increase bar arrangement (example 4) significantly improved the cooling efficiency by increasing the turbulence of the cooling gas. The improved cooling is shown by the shorter heat signature (Figure 5) and a greater thickness per filament (Figure 6) achieved with the turbulence improvement bar arrangement.

.J 28Ü »; -.

Other variations of the turbulence enhancement rod arrangement shown in Figure 1 are also considered to be within the scope of the invention. For example, the horizontal bars generally 12 are not limited to the circular cross section (illustrated in Fig. 2). The bars may have any shape in cross section that includes without limitation triangles, rectangles, ellipses, nails, diamonds, trapezoids and parallelepipeds. The size spacing between the bars is the most important factor in inducing turbulence, for the reasons explained above. It is also possible to have cross bars that intersect the bars, provided that the distance between the cross bars is at least as large as the minimum spacing between the bars. Preferably, any transverse bars are smaller and moreover they separate more than the bars so as not to significantly interfere with the increased turbulence effects of the bars. More specifically there are no cross bars that intersect the generally horizontal bars, except for the side bars 14 at the ends (figure 1).

Although the embodiments of the invention described herein are presently preferred, various modifications and improvements may be made without departing from the spirit and scope of the invention. The scope of the invention is indicated by the appended claims and all the changes that fall therein «Faith,» - «.- Ailfe. «- ^ > .J •. * • - "of the meaning and range of equivalents of intent to be covered by it.

Claims (26)

R E I V I N D I C A C I O N S

1. A method for cooling nonwoven filaments comprising the steps of: extrude a group of non-woven filaments from a spinning organ; Y cooling nonwoven filaments by; applying a cooling gas to the group of non-woven filaments under turbulent flow conditions. t

2. The method, as claimed in clause 1, characterized in that the cooling gas applied to the filaments has a turbulence intensity of at least about 5%.

3. The method, as claimed in clause 1, characterized in that the cooling gas applied to the filaments has a turbulence intensity of at least 10%

4. The method, as claimed in clause 1, characterized in that the cooling gas applied to the filaments has a turbulence intensity of at least 20% . '-fcasaS; ..

5. The method, as claimed in clause 1, characterized in that the cooling gas comprises air.

6. The method, as claimed in clause 1, characterized in that the step of passing the cooling gas through an array of turbulence-inducing bars includes a plurality of bars, before applying it to the bundle of filaments.

7. The method, as claimed in clause 6, characterized in that the bars are essentially parallel to one another.

8. The method, as claimed in clause 6, characterized in that the bars are essentially perpendicular to the group of filaments that are being extruded.

9. The method, as claimed in clause 1, characterized in that the cooling gas supplied at a rate of about 50-500 feet per minute. - * & tgl? .1

10. The method, as claimed in clause 9, characterized by the flow velocity ee of about 100-400 feet per minute.

11. The method, as claimed in clause 9, characterized in that the flow velocity ee of about 200-300 feet per minute.

12. An apparatus for producing chilled nonwoven filaments comprising: a spinner organ for extruding a nonwoven filament group in a trajectory; a supply apparatus communicating with the path to apply the cooling gas to the group of non-woven filaments after extrusion; Y an arrangement of turbulence inductor bar positioned between the supply apparatus and the path to increase the turbulence of the cooling gas applied to the group of non-woven filaments; A bar arrangement includes a plurality of bars and spaces between the bars. ^ íft a > <

13. The apparatus, as claimed in clause 12, characterized by the arrangement of bars occupies a flat area, the bars occupy about 20-80% of the planar area and the spaces between the bars occupy about 20-80% of the planar area.

14. The apparatus, as claimed in clause 13, characterized in that the bars occupy about 30-70% of the planar area and the spaces between the bars occupy about 30-70% of the planar area.

15. The apparatus, as claimed in clause 13, characterized in that the bars occupy about 40-60% of the planar area and the spaces between the bars occupy about 40-60% of the planar area.

16. The apparatus, as claimed in clause 12, characterized in that the bars have an average width of about 0.125-1.00 inches.

17. The apparatus as claimed in clause 12, characterized in that the bars have an average width of about 0.25-0.75 inches. ^ • ilKff

18. The apparatus as claimed in clause 12, characterized in that the bars have an average width of about 0.40-0.60 inches.

19. The apparatus as claimed in clause 12, characterized in that the bars are present at about 6-50 bars per foot of length of the bar arrangement.

20. The apparatus as claimed in clause 12, characterized in that the bars are present at around 8-25 bars per foot of length of the bar arrangement.

21. The apparatus as claimed in clause 12, characterized in that the bars are present at around 10-15 bars per foot of length of the bar arrangement.

22. The apparatus, as claimed in clause 12, characterized in that the bars are essentially parallel to one another.

23. The apparatus, as claimed in clause 12, characterized in that the bars are essentially horizontal.

24. The apparatus, as claimed in clause 12, characterized in that the bars are essentially perpendicular to the path.

25. The apparatus, as claimed in clause 12, characterized in that the bars have cross-sectional formae selected from the group consisting of circles, triangles, rectangles, ellipses, nails, diamonds, trapezoids and parallelepipeds.

26. A cooling apparatus comprising., a supply apparatus for generating a cooling gas stream; Y an arrangement of turbulence inductor bar placed in a gas cooling stream; the array of bars includes a plurality of bars that induce essentially parallel turbulence and open spaces between the bars; the array of bars further includes a pair of transverse bars that intersect and hold the bars essentially parallel but otherwise are essentially devoid of transverse bars. SUMMARY A method and apparatus for improving the cooling of the non-woven filaments using an arrangement of turbulence-inducing rods placed in a stream of cooling gas between the gas supply apparatus; of cooling and the group of filaments that is being extruded. The bar arrangement increases the turbulence of the cooling gas so that the gas applied to the group of filaments has a turbulence intensity of at least about 5%. The turbulent cooling gas penetrates into the bundle of filaments to provide more efficient heat removal.