MXPA98007670A - Process for the manufacture of non-woven fabric made of fused filaments between - Google Patents

Abstract

An improved process and apparatus for the formation of a fibrous non-woven fabric, made of fused filaments, suitable for service in end uses of nonwovens, is described. A melt-processable thermoplastic polymeric material is melt-extruded to form a multi-filament spin line (2), cooled and wound around at least two driven, spaced-apart stretch rollers (14, 16). , which are surrounded by a cover (12), before harvesting to form a fabric (40) and joined to form a nonwoven product made of fused filaments. The stretching rollers (14, 16) exert a pulling force on the multi-filament spinning line (2), to carry out the stretching of the melted, multi-filament spinning line (2) before solidification complete The cover (12) makes it possible to self-tension the spinning line (2) around the stretching rollers (14, 16). A pneumatic jet (32), located at the outlet end (24) of the cover, assists in the contact of the multi-filament spinning line (2) with the stretching rollers (14, 16) in order to facilitate the imposing a uniform pulling force and ejecting the yarn line (2) of multiple filaments, in the direction of its length, towards a support (38) where it is collected. The formation of a non-woven product, made of fused filaments, highly uniform, is made possible on an expeditious basis.

Description

PROCESS FOR THE MANUFACTURE OF NON-WOVEN FABRIC MADE OF FUSED FILAMENTS BETWEEN YES BACKGROUND OF THE INVENTION Non-woven fabrics made of fused filaments are important trade items for consumer use and industrial end uses. Such products commonly possess a touch (of cloth) and textile-like appearance and are. useful as a component of disposable diapers, in automotive applications and in the formation of medical garments, household furnishings, filtration media, carpet base, softening substrates for fabrics, roofing boards, geotextiles, etc. According to prior art technology, melt-processable thermoplastic polymer material is passed through a spinneret to form a multi-filament fibrous yarn line, stretched to increase its toughness, it is passed through a cooling zone where solidification occurs, is collected on a support to form a fabric and joins together to form a non-woven fabric made of fused filaments. Stretching or- the spinning line extruded in the molten state has been carried out in the past by passing through a REF stream. 28338 pneumatic or by winding around driven stretch rollers. An arrangement of apparatus using the stretching and gas flow rolls is described in U.S. Patent No. 5,439,364. The equipment used for the production of non-woven fabric made of fused filaments has in the past required relatively high capital expenditures, multiple spinning positions, large volumes of air and / or presented disadvantages of denier variability when needed. the rapid formation of a non-woven product on an economic basis. It is an object of the present invention to provide an improved process for the formation of a non-woven fabric, made of filaments fused together. It is an object of the present invention to provide a process for the formation of a non-woven fabric made of fused filaments, which can be carried out on an expedited base to form a substantially uniform product, having a satisfactory balance of properties. It is an object of the present invention to provide a process for the formation of a non-woven fabric, made of fused filaments which is relatively compatible with the environment and which offers the possibility of systematically producing a non-woven product of - - Detrimental effects of the roller. It is an object of the present invention to provide an improved process for the formation of a non-woven fabric, made of fused filaments, where the spinning line is capable of self-undercoxing or threading and requires minimal intervention of the operator. It is an object of the present invention to provide an improved technology that is flexible with respect to the chemical composition of the melt-processable thermoplastic polymeric material that serves as the starting material. It is an object of the present invention to provide a process that is capable of producing, with good denier control, a non-woven fabric product made of lightweight, substantially uniform fused filaments at relatively high spinning speeds in a reliable base. It is another object of the present invention to provide an improved process for the formation of a non-woven fabric made of fused filaments to each other while making a reduced capital expense possible as well as reduced operating costs.

It is still another object of the present invention to provide a process for forming a non-woven fabric, made of fused filaments where reduced operating costs are possible with respect to airflow requirements, when compared to the technology. previous that involves the use of a forward air jet to carry out the attenuation. It is a further object of the present invention to provide an improved apparatus for the formation of a non-woven fabric made of fused filaments together. These and other objects, also as the scope, nature and use of the invention will be apparent to those skilled in the non-woven technology from the following detailed description and the appended claims.

BRIEF DESCRIPTION OF THE INVENTION It has been found that, in a process for the formation of a non-woven fabric, made of fused filaments, where a polymeric material processable in the molten state is passed through a plurality of extrusion orifices. To form a multi-filament spinning line, the multi-filament spinning line is stretched in order to increase its tenacity, it is passed through an area of cooling where solidification occurs, is collected on a support to form a fabric and is bonded or glued to form a non-woven fabric made of fused filaments; improved results are obtained by passing the multi-filament spinning line in the direction of its intermediate length to the cooling zone and the support, while being rolled or wrapped around at least two spaced, spaced-apart stretching rollers. which are surrounded in the areas where the multi-filament spinning line is brought into contact with the stretching rolls, by a cover having an inlet end and an outlet end, which is provided in such a way that the The cover entrance receives the multi-filament spinning line and a pulling force is exerted on the spinning line of. multiple filaments mainly by the action of the driven, stretched stretching rollers, to carry out the stretch thereof (spinning line) adjacent to the extrusion holes and exert an additional tensile force on the yarn spinning line. multiple filaments by passing it through a pneumatic feed jet, located at the outlet end of the cover, which aids in contacting the multi-filament spinning line with the driven, spaced stretch rollers and ejects the multi-strand yarn line in the direction of its length from the outlet end of the cover to the support. An apparatus for the production of a non-woven fabric made of fused filaments is provided, which comprises in combination: (a) a plurality of melt extrusion holes capable of forming a multi-filament spinning line, in the extrusion of a molten thermoplastic polymeric material, (b) a cooling zone capable of carrying out the solidification of the molten, multi-filament thermoplastic polymer yarn line, after extrusion in the molten state thereof, _ (c) by at least two spaced, driven, stretching rollers located downstream of the cooling zone, which are surrounded in the areas where the multi-filament thermoplastic polymer yarn line would be contacted with the rollers, by a cover having a end of entry and an exit end, which is provided in such a way that the roof is able to receive the line of spinning polim thermoplastic multi-filament sterilizer and stretch rollers have the ability to exert a tensile force on the polymer yarn line thermoplastic of multiple filaments, to carry out the stretching of the same adjacent to the extrusion orifices, (d) a jet of pneumatic advance located at the exit end of the cover, which is able to assist the contact of the line of multi-filament thermoplastic polymer yarn with the drawn, spaced stretch rollers and is further capable of ejecting the multi-filament thermoplastic polymer yarn line in the direction of its length from the outlet end of the cover, (e) a localized support in a spaced relationship below the pneumatic advance jet, which is capable of receiving the multi-filament thermoplastic polymer yarn line and facilitating the laying of the same to form a fabric, and (f) joining means capable of joining or gluing the multi-filament thermoplastic polymer yarn line after the formation of the fabric to form a non-woven fabric made of filaments fused together DESCRIPTION OF THE DRAWINGS The drawings in figure "1 consist of a schematic representation of an arrangement of the apparatus according to the present invention, which is capable of carrying The process was prayed for the production of a non-woven fabric, made of fused filaments, according to the present invention. Figure 2 illustrates, in cross section, in greater detail, the nature of the polymeric edges which may be located in areas where the cover approaches or approaches the drawing rollers to provide a substantially continuous passage or passage.

DESCRIPTION OF THE PREFERRED EMBODIMENTS The starting material for use in the production of a non-woven fabric made of fused filaments is a melt processable thermoplastic polymer material, which has the ability to be extruded in the molten state to form continuous filaments. Suitable polyolefin materials include polyolefins, such as polypropylene and polyesters. Isotactic polypropylene is the preferred form of polypropylene. A particularly preferred isotactic polypropylene exhibits a melt flow rate of about 4 to 50 grams / 10 minutes, as determined by the ASTM D-1238 standard. Polyesters are commonly formed by the reaction of an aromatic dicarboxylic acid (for example, terephthalic acid, isophthalic acid, naphthalenedicarboxylic acid, etc.) and an alkylene glycol ( e emp e, e englico, propilenglicol, etc.) as the diol. In a preferred embodiment, the polyester consists primarily of polyethylene terephthalate. A particularly preferred polyethylene terephthalate starting material has an intrinsic viscosity (IV) of about 0.64 to 0.69 (eg, 0.635) grams per deciliter, a glass transition temperature of about 75 to 80 ° C and a melting temperature of approximately 260 ° C. Such intrinsic viscosity can be determined when 0.1 g of polyethylene terephthalate are dissolved by 25 ml of solvent consisting of a 1: 1 by weight mixture of trifluoroacetic acid and methylene chloride, while using a Cannon-Fenske viscometer No. 50 to 25 ° C. Other recurring units copolymerized within the polymer chains that polyethylene terephthalate may optionally have at lower concentrations. Also, some polyethylene isophthalate filaments may optionally be included in the polyester spin line at a lower concentration, to make the resulting fabric more prone to thermal bonding. Additional representative plasticplastic polymeric materials include polyamides (e.g., nylon-6 and nylon-6, 6), polyethylene (e.g., high density polyethylene), polyurethane, etc. Since the technology of the present invention is relatively environmentally compatible, it is it is further possible to use a recyclable and / or residual melt processable thermoplastic polymeric material (eg, recycled polyethylene terephthalate). When the starting thermoplastic polymeric material is a polyester (e.g., polyethylene terephthalate), it is recommended that the polymer particles thereof be pretreated by heating with stirring, at a temperature higher than the glass transition temperature and lower than the temperature of the glass. melting, for a period of time sufficient to expel the moisture and effect a physical modification of the surfaces of the particles, to render them substantially non-adherent. Such pretreatment results in an ordering or crystallization of the surfaces of the particulate starting material and thereafter allows the polymer particles to flow and be transferred in an easily controllable manner when supplied or fed to the apparatus for melt extrusion. . In the absence of such pretreatment, the polyester particles tend to accumulate. Starting materials, such as isotactic polypropylene, do not need to be subjected to such pretreatment, since they inherently lack a propensity for agglomeration. The moisture content of a The polyethylene terephthalate preferably does not exceed 25 ppm before extrusion. The melt-processable thermoplastic polymeric material is heated to a temperature higher than its melting temperature (e.g., commonly at a temperature of about 20 to 60 ° C, above the melting temperature) and passed to a plurality. of holes for extrusion in the molten state (that is, a row for extrusion of yarns having a plurality of openings or holes). Commonly, the polymeric material melts as it passes through a heated extruder, is filtered while passing through a spin pack located in a spin block and is passed through the extrusion orifices to a controlled speed, by using a dosing pump. It is important that any solid particulate material be separated from the molten thermoplastic polymer to prevent blockage of holes or holes in the spinneret. The size of the extrusion holes is selected in such a manner as to enable the formation of a multi-filament spinning line, wherein the individual filaments are of the desired denier after stretching or elongation, before complete solidification, such as it is described later in the present. The diameters of or suitable for extrusion orchids, they commonly fluctuate from about 0.254 to 0.762 mm (10 to 30 thousandths of an inch). Such cross sections of the hole or hole may be circular in configuration or may assume other configurations, such as trilobal, octalobal, star, bone, etc. Representative pack pressures of about 8,268 to 41,340 KPa (1,200 to 6,000 psi) with polyethylene terephthalate and about 6,890 to 31,0005 KPa (1,000 to 4,5000 psi) are commonly employed with isotactic polypropylene. When polyethylene terephthalate is the starting material, the representative polymer output or throughput rates commonly range from 0.4 to 2.0 grams / minute / hole and when the isotactic polypropylene is the starting material, the output speeds of yield Representative polymer ranges normally from 0.2 to 1.5 grams / minute / hole. The number of extrusion holes and their arrangement can be varied widely. Such number of holes. extrusion corresponds to the number of continuous filaments contemplated in the resulting multi-filament fibrous material. For example, the number of extrusion holes can commonly fluctuate from about 200 to 65,000. Such holes are commonly provided at a frequency of about 2 to 16 per cm2 (10 to 100 per inch). In a preferred embodiment, the extrusion orifices are arranged in a rectilinear configuration (that is, as a spinneret row extrusion line). For example, such rows for extrusion of straight yarns can have widths of about 0.1 to 4.0 meters (3.9 to 157.5 inches) or more, depending on the width of the non-woven fabric made of fused filaments to each other to be formed. Alternatively, a multi-position spinning arrangement can be used. A cooling zone, capable of carrying out the solidification of the molten thermoplastic polymer filament line, melted, next to the melt extrusion, is located below the extrusion orifices. The melted multi-strand yarn line is passed in the direction of its length through the cooling zone provided with a low velocity gas and a high volume, where it is preferably cooled in a substantially uniform manner in absence of undue turbulence. Within the cooling zone / melted multi-filament spinning line, it goes from the consistency of melted to semi-solid and of the semi-solid consistency to a fully solid consistency. Before solidification, when - it is present immediately below the extrusion holes, the multi-filament spinning line experiences a Stretching and substantial orientation of the polymer molecules. The gaseous atmosphere present within the cooling zone preferably circulates to effect a more efficient heat transfer. In a preferred embodiment of the process, the gaseous atmosphere of the cooling zone is provided at a temperature of about 10 to 60 ° C (for example 10 to 50 ° C) and more preferably at about 10 to 30 ° C (for example example, at room temperature or a lower temperature). The chemical composition of the gaseous atmosphere is not critical to the operation of the process, provided that the gaseous atmosphere is not unduly reactive with the molten thermoplastic polymer material. In a particularly preferred embodiment of the process, the gaseous atmosphere in the cooling zone consists of air having a relative humidity of about 50 percent. The gaseous atmosphere is preferably introduced to the cooling zone in a cross-flow configuration and collides in a substantially continuous manner on one or both sides of the spinning line. Other flow arrangements of. Cooling can be used similarly. Typical lengths for the cooling zone commonly range from 0.5 to 2.0 m (19.7 to 78.7 inches). Such a cooling zone can be enclosed and provided with means for the controlled extraction of the gas flow that is N o w e r a m m e or m e m e m e m e n e can be er parc al o completely to the atmosphere- ircundant. The solidified multi-filament spinning line is wrapped or wound around at least two spaced-out, drawn stretching rollers that are surrounded by a cover in the areas where the multi-filament spinning line is wound around the rollers. If desired, one or more additional pairs of spaced-apart stretching rollers can be supplied in series and similarly surrounded by the same continuous cover. The multi-strand spinning line is normally wound around the stretching rolls at winding angles of about 90 to 270 degrees and preferably at winding angles in the range of about 180 to 230 degrees. The cover is provided in a spaced relation to the stretching rollers and provides a continuous channel, in which the spinning line can pass freely. The stretching rollers exert a pulling force on the spinning line to carry out stretching thereof adjacent to the extrusion holes and before completing the solidification in the cooling zone. At the exit end of the cover is located a pneumatic advance jet, which helps in the contact of the multi-filament spinning line with the stretching rollers spaced apart and ejects the multi-filament spinning line in the direction of its length from the outlet end of the cover to a support, where it is collected as described hereinafter. The driven stretch rollers, which are used according to the present invention, have lengths that exceed the width of the multi-filament fibrous web, made of fused filaments, which is formed. Such draw rolls can be formed from cast or machined aluminum or other durable material. The surface of the stretching rollers are preferably smooth. Representative diameters for stretch rolls commonly fluctuate from about 10 to 60 cm (3.9 to 23.6 inches). In a preferred embodiment, the diameter of the stretching roller is approximately 15 to 35 cm (5.9 to 13.8 inches). As will be apparent to those experienced in fiber technology, the diameter of the roll and the winding angle of the spinning line will largely determine the spaced relationship of the stretching rolls. During the operation of the process of the present invention, the draw rolls are commonly driven at surface speeds in the range of about 1,000 to 5,000 or more, meters per minute (1,094 to 5,468 yards / minute) and preferably at surface speeds in the range of approximately 1,500 to 3,5000 meters per minute (1,635 to 3,815 yards / minute). The driven stretching rollers impart a pulling force to the multi-filament spinning line, which effects a substantial stretching of the spinning line, which is carried out in an upstream area, before the complete solidification of the yarns. individual filaments present in it. The presence of a cover or wrap surrounding the draw rolls is a key feature of the overall technology of the present invention. Such a cover is sufficiently spaced from the surfaces of the stretching rollers to provide a continuous unobstructed enclosed passage or passage to accommodate the multi-filament spinning line that is wrapped or wound on the stretching rollers, also to accommodate the flow uninterrupted gas from the inlet end to the outlet end. In a preferred embodiment, the inner surface of the casing or shell of the casing is spaced not more than about 2.5 cm (1 inch) from the draw rolls and not less than about 0.6 cm (0.254 inches) from the draw rolls. A jet of pneumatic advance, in communication with the outlet end of the cover, causes a gas, such as air, is drawn to the inlet end of the cover, to flow uniformly around the surface of the stretching rolls that carry the multi-filament spinning line and to be expelled downward and outward from such a jet of pneumatic advance . The cover defining the outer border of such continuous passage is provided as a bell around the stretching rollers and can be formed of any durable material, such as polymeric or metallic materials. In a preferred embodiment, the cover is formed, at least partially, of a clear, strong polymeric material, such as polycarbonate bonded material, which allows easy observation of the spinning line from the outside. If the spacing of the cover, with respect to the stretching rollers, is too distant, the velocity of the gas flow in the cover tends to become unduly low, to prevent the imposition of the desired improved contact between the multi-yarn line. filaments and driven stretch rollers. For best results, the confined gas flow area created within the cover is uniform and substantially free of obstruction or areas where gas dissipation could occur over the entire length of the cover from its inlet end to the end of. departure. This prevents any substantial interruption or loss of gas flow at an intermediate site within the cover, during the practice of the present invention. When the gas flow within the cover is substantially continuous and unaltered, such flow achieves its proposed function of improving contact between the driven stretch rollers and the multi-filament spinning line that is wound onto such stretch rollers. The possibility of slippage of the multi-filament spinning line when rolling on the stretching rollers is largely overcome or minimized. In a preferred embodiment of the present invention, the cover includes polymeric edges or extensions (ie, aerodynamic deflectors) that have the ability to be positioned in close proximity to the driven stretch rollers at all roller lengths in areas immediately following the points where the multi-strand spinning line of the stretching rolls comes out and immediately before the point where the multi-strand spinning line engages with the second stretching roll. This makes possible a substantially complete wrapping of the stretching rollers with such edges, preferably capable of rapid disintegration, preferably as a fine powder, when contacting the stretching rollers. Such polymeric edges they preferably have a relatively high melting temperature and approach each draw roller while leaving a very light opening of the order of 0.1 to 0.08 mm (0.5 to 3 mils). Representative polymeric materials suitable for use when forming the polymeric edges include polyamides, polyamides, polyesters, polytetrafluoroethylene, etc. Fillers such as graphite may optionally be present therein. The uniform gas flow within the cover is maintained and the undesirable roller wraps of the multi-filament spinning line are prevented. Thus, the need to stop or stop the spinning line in order to correct roll coils is greatly minimized and the ability to continuously form a uniform product of non-woven fabric made of fused filaments is improved. The pneumatic feed jet, located at the outlet end of the cover, provides a continuous downward directed gas flow, such as air flow, at the outlet end of the cover. Such a feed jet introduces a gas flow substantially parallel to the movement of the spinning line, while the spinning line passes through an opening provided in the pneumatic feed jet. A continuous gas flow is created in all the cover by means of aspiration imparted by the pneumatic feed jet, with a supply of gas that is additionally extracted to the inlet end of the cover and flowing along the entire length of the cover. The gas flow entering through the inlet end of the cover merges with that introduced by the pneumatic advance jet. The gas flowing down, introduced by such a jet of pneumatic advance, collides with the spinning line and exerts an additional pulling force thereon, sufficient to help maintain a uniform roller contact, in the substantial absence of slippage. The velocity of the gas imparted by the pneumatic advancing jet exceeds or is greater than the surface velocity of the driven drawing rollers, such that the required tensile force is made possible. It has been found that such a jet of pneumatic advance, with the help of the air flow created in the cover, facilitates the good contact with the stretching rollers, in order to make possible the uniform stretching of the continuous filaments within the non-woven product. resulting. The pneumatic feed jet creates a tension on the spinning line that helps keep the spinning line in good contact with the stretching rollers. An upper filament denier uniformity product is formed, while preventing slippage between the multi-filament spinning line and the rollers of stretch, in the context of the overall process. Such a jet of pneumatic advance does not serve for any substantial function of stretching or elongation of the filament, the stretching force is created mainly by the rotation of the driven stretching rollers. Pneumatic advance jets capable of advancing a multi-filament spinning line, as they pass through them, while exerting sufficient tension to retain the spinning line on the stretching rollers in the substantial absence of Slip If desired, an electrostatic charge can optionally be imparted to the mobile yarn line, from a low voltage, high amperage source, according to known technology, to assist in the laying of filaments on the support (described later in I presented) .

The support is located in a spaced relation below the pneumatic feed jet which is capable of receiving the multi-filament spinning line and facilitates the laying thereof to form a fabric. Such a support is preferably a rotating belt that moves continuously and highly impermeable to air, such as that commonly used during the formation of a non-woven fabric made of fused filaments, where a partial vacuum is applied from below. such a band, which contributes to the laying of the multiple yarn line filaments on the support to form a fabric. The vacuum applied from below preferably balances to some degree the air emitted by the pneumatic feed jet. The unit weight of the resulting fabric can be adjusted at will by means of a change in the speed of the rotating moving belt on which the fabric is collected. The support is provided in a spaced relation below the pneumatic feed jet, at a distance sufficient to allow the multi-filament spinning line to spontaneously braid and wave to at least some extent as its forward movement is braked before that is deposited on the support in a substantially random or disorderly manner. An excessively high fiber alloy in the machine direction is prevented in view of the substantially random laying during the formation of the fabric. Next, the multi-filament spinning line is passed from the harvesting pad to a bonding or bonding device, where the adjacent filaments are joined together to produce a non-woven fabric made of fused filaments. Commonly, the fabric is further compacted by mechanical means prior to undergoing adhesion or bonding, in accordance with the technology commonly used in the non-woven technologies of the prior art. During the union, portions of the multi-filament product commonly pass through a heated, high-pressure roll gap assembly and are heated to the melting temperature or softening temperature, wherein the attached filaments undergoing such heating are caused to permanently merge or merge jointly at crossing points. Union can be imparted in geometric figures (ie, punctual) by using a calender or surface bond (ie, the area) across the entire surface of the fabric, in accordance with techniques known in the art. Preferably, such bonding or adhesion is obtained by thermal adhesion by means of the simultaneous application of heat and pressure. In a particularly preferred embodiment, the resulting fabric is joined at intermittent spaced sites, while a configuration selected in such a way as to be compatible with the end use contemplated is used. Typical bonding or adhesion pressures range from about 17.9 to 89.4 Kg / linear cm (100 to 500 linear pounds / inch) and the bonding areas commonly fluctuate from about 10 to 30 percent of the surface that undergoes such bonding in figures geometric The rollers can be heated by means of circulating oil or by induction heating, etc. Such bonding or thermal adhesion is described in U.S. Patent No. 5,298,097, which is incorporated herein by reference. The nonwoven fabric made of fused filaments of the present invention usually includes continuous filaments of about 1.1 to 22 dTex (1 to 20 denier). The preferred filament dTex for polyethylene terephthalate is from about 0.55 to 8.8 (0.5 to 8 denier) and more preferably from 1.6 to 5.5 (1.5 to 5 denier). The preferred filament dTex for isotactic polypropylene is from about 1.1 to 11 (1 to 10 denier) and more preferably 2.2 to 4.4 (2 to 4 denier). Commonly, a tenacity of the polyethylene terephthalate filament of about 2.2 to 3.4 dN / dTex (2.0 to 3.1 grams per denier) and a tenacity of the isotactic polypropylene filament of 13.2 to 17.7 dN / dTex (1.5 to 2 grams per denier) is obtained in non-woven fabrics made of fused filaments, formed in accordance with the present invention. Non-woven fabrics, relatively uniform, having a basis weight of about 13.6 to 271.7 g / m2 (0.4 to 8.0 ounces / yard2) are commonly formed. In a preferred embodiment, the weight basis is from about 13.6 to 67.9 g / m2 (0.4 to 2.0 ounces / yard2). The nonwoven products preferably having a unit weight coefficient of fabric variation at least as low as 4 percent, as determined in a sample of 232 cm (36 inches) can be formed according to the technology of the present invention. The technology of the present invention is capable of forming a nonwoven fabric made of filaments fused together, highly uniform, on an expedited basis, in the absence of highly expensive capital and operating requirements. Additional possible economies are made by the ability to use a residual and / or recycled thermoplastic polymeric material as the starting material. The capacity of autoencordelado or self-threading of the technology also ensures a minimum start-up activity for workers, to maximize by this the production of a given installation. The following examples are given as specific illustrations of the present invention with reference to Figure 1 and Figure 2 of the drawings. However, it should be understood that the invention is not limited to the specific details summarized in the examples. In each instance, the thermoplastic polymeric material, while in the form of flakes, is fed to an extruder of a single heated MPM worm (not shown) and is fed while in the molten state through a transfer line heated to a Zenith pump (not shown) that has a capacity of 11.68 cmVrevolution (0.71) inch / revolution) to package 1 / row assembly for yarn extrusion. The control pressure of the extruder is maintained at approximately 3445 KPa (500"pounds / inch2) .The thermoplastic polymer, while in the molten state, passes through the package 1 assembly / spinneret for spinning, which includes a filtration medium for forming a molten, thermoplastic, multi-filament polymer yarn line 2. Then, the resulting multi-filament yarn line is cooled as it passes through the cooling zone 4 having a length of 0.91 m (36 inches), wherein the air, at a temperature of about 13 ° C, is brought into contact with the spinning line in a substantially perpendicular and non-turbulent manner from a side that was fed through line 6 and it is introduced at a flow rate of 35.9 cm / second (110 feet / minute) A lower portion of the spinning line B immediately enters the entrance end 10 of the cover 12 surrounding the rollers 14 and 16, in areas where the spinning line is wound or wrapped around such stretching rollers. The stretching rollers 14 and 16 have diameters of 19.4 cm (7.6 inches). The spinning line is brought into contact with each stretching roller at an angle of about 210 degrees. The inner surface of the cover 12 is spaced at a distance of approximately 2.5 cm (1 inch) from the surfaces of the stretching rollers 14 and 16 in areas where the spinning line is wound around such rollers. As shown in Figure 1, the polymer extensions or edges 18, 20 and 22 are provided to facilitate the formation of a substantially complete passage from the inlet end 10 to the outlet end 24 of the cover 12. The details of an extension or representative polymeric rim are shown in greater detail in Figure 2, wherein the replaceable polymeric rim 26 is mounted on the carrier 28 of the cover 12. The polymeric rim 26 and the carrier 28 form a portion of the cover 12 through the liner 12. which passes the spinning line The polymeric edge or extension 18 of Figure 1 corresponds to the replaceable polymeric edge 26 with the carrier 28 of Figure 2. Any contact of the polymeric edge 26 with the stretching roller 14 causes the disintegration of such edge as a powder without any significant damage to such stretch roller In figure 2, the spin line is indicated at 30, as it leaves the first draw roller nto 14. The stretching rollers 14 and 16, as shown in FIG. 1, facilitate the stretching of the spinning line 2 before its complete solidification.

At the outlet end 24 of the cover 12 is located the jet of pneumatic advance 32, where air is introduced through the conduit 34 and is directed downwards substantially parallel to the direction of movement of the spinning line. The air pressure in the jet is 186 KPa (27 pounds / inches2) and approximately 4.2 m3 (150 feet) of air is consumed per minute. The air velocity imparted by the pneumatic feed jet 32 exceeds the surface velocity of the draw rollers 14 and 16. The pneumatic feed jet 32 imparts an additional pulling force on the spinning line, causes the additional air to be sucked in. to the cover 12 at the inlet end 10, it creates an air flow over the entire length of the cover 12 and facilitates a uniform wrapping or winding of the spinning line on the stretching rollers 14 and 16, in the substantial absence of slippage , in such a way that uniform stretching is possible. Also, the jet of pneumatic advance 32 causes the spinning line 36 to be ejected from the outlet end 24 of the cover 12 towards the support 38 which is provided as a mobile, air permeable web. As the spinning line 36 leaves the jet 32 of pneumatic advance, the individual continuous filaments present therein undulate in a manner in general random or disorderly, as the speed of the spinning line decreases and its forward movement slows down, since a vigorous pulling force is no longer exerted on it. Next, the spinning line is collected on the support 38 in a substantially random or disorderly manner. Such a support or laying band 38 is commercially available from Albany International of Portland, Tennessee, under the trade designation Electrotech 20. The support 38 is positioned in a spaced relationship below the exit orifice of the pneumatic feed jet 32. The resulting fabric 40, as long as it is present on the support 38 is passed immediately around the compaction roll 42, and the joining roll 44 in geometric figures. The connecting roller 44 in geometric figures has a diamond geometrical shape or figure engraved on its surface and is stripped to achieve the softening of the thermoplastic polymer material. The bonded or glued areas, which extend over about 20 percent of the surface of the fabric, are obtained as the yarn passes between the compaction roll 42 and the jointing roll 44 in geometric figures. Next, the non-woven fabric, made of filaments fused together, resulting, is rolled up and Recover in It is important to consider what examples are specified later in this document.

Example 1 The thermoplastic polymeric material consists of commercially available polyethylene terephthalate having an intrinsic viscosity of 0.685 grams per deciliter. The intrinsic viscosity is determined as described above. Such a polymeric material, while initially in the form of flakes, is pre-treated at a temperature of about 174 ° C to obtain crystallization and dried in dehydrated air at a temperature of about 149 ° C. A spin package pressure of 13,780 KPa (2,000 pounds / inch2) is used. The row for spinning extrusion consists of 384 holes evenly spaced across a width of 15.2 cm (6 inches). The capillaries of the row for extrusion of yarns have a tplobal configuration, with a slot length of 0.38 mm (0.015 inches), a slot depth of 0.18 mm (0.0007 inches) and a slot width of 0.13 mm (0.005 inches) . Molten polyethylene terephthalate is fed at a rate of 1.2 grams / minute / hole - and extruded at a temperature of 307 ° C.

The driven stretching rollers 14 and 16 are rotated at a surface speed of about 2, 743 meters / minute (3,000 yards / minute). The filaments of the product have a dTex of about 4.5 (one denier of 4.1) and a tenacity of about 20.3 dN / dTex (2.3 grams per denier). The speed of the laying band 38 is varied to form non-woven fabrics made of fused filaments that vary in unit weight from 13.6 to 135.8 g / m2 (0.4 to 4.0 ounces / yard2). A non-woven fabric product made of fused filaments, having a unit weight of 105.3 g / m2 (3.1 ounces / yard ') exhibits a unit weight coefficient of variation of only 4 percent on a 232 cm2 sample ( 36 inches).

Example 2 The thermoplastic polymer - consists of commercially available isotactic polypropylene, having a melt flow rate of 40 grams / 10 minutes, as determined by the ASTM D-1238 standard. Such a polymeric material is fed in the form of flakes and extruded in the molten state. A spin package pressure of 9,646 KPa (1,400 pounds / inch2) is used. The row for spinning extrusion consists of 240 holes evenly spaced through e an an e e. cm pu ga as. The row and row for the extrusion of yarns has a circular configuration with a diameter of 0.038 cm (0. ~ 015 inches) and a slot length of 0.152 cm (0.060 inches). Molten isotactic polypropylene is fed at a rate of 0.6 grams / minute / hole and extruded at a temperature of 227 ° C. The driven rollers 14 and 16 are rotated by one. surface velocity of approximately 1,829 meters / minute (2,000 yards / minute). The filaments of the product possess a dTex of approximately 3.3 (denier of 3.0) and a toughness of approximately 15.9 dN / dTex (1.8 grams per denier). The speed of the laying band 38 is varied to form non-woven fabrics made of fused filaments, which vary in unit weight from 13.6 to 67.9 g / m2 (0.4 to 2.0 ounces / yard2). A product made of fused filaments, having a unit weight of 44.1 g / m2 (1.3 ounces / yard2) exhibits a unit weight variation coefficient of only 3.3 percent with respect to a 232 cm (36 inch) sample . Although the invention has been described with preferred embodiments, it will be understood that variations and modifications may be resorted to, as will be apparent to those skilled in the art. It is considered that such Variations and motions are within the spirit and scope of the claims appended hereto. It is noted that, in relation to this date, the best method known to the applicant to carry out the aforementioned invention, is that which is clear from the present description of the invention. Having described the invention as above, property is claimed as contained in the following

Claims (1)

1. EVIDENCE 1. An improved process for the formation of a non-woven fabric made of fused filaments, characterized in that a melt processable thermoplastic polymer material is passed through a plurality of extrusion holes to form a Multi-filament spinning line, the multi-filament spinning line is stretched in order to increase its tenacity, it is passed through a cooling zone, where solidification occurs, it is collected on a support to form a fabric and fuses or joins together to form a non-woven fabric made of fused filaments; the improvement consists in passing the multi-filament spinning line in the direction of its intermediate length to the cooling zone and the support, while wrapping or wrapping around at least two spaced, driven stretching rollers which are surrounded, in the areas where the multi-filament spinning line is brought into contact with the rollers, by a cover having an inlet end and an outlet end, which is provided in such a way that the inlet end the cover receives the multi-filament spinning line and a pulling force is exerted on the multi-filament spinning line, mainly by the action of the rollers. It is also known as space, to carry out the stretching of the same, adjacent to the extrusion processes and to exert an additional tensile force on the multi-filament spinning line, when passing it through of a pneumatic feed jet, located at the end of the cover, which aids in the contact of the multi-filament spinning line with the driven, spaced stretching rollers and expels the multi-filament spinning line in the direction of its length from the outlet end of the cover to the support 2. The process accor to claim 1, characterized in that the thermoplastic, moldable processable polimepco material is mainly polyethylene terephthalate 3. The process accor to claim 1 , characterized in that the thermoplastic polymer material processable in the molten state is polypropylene. 4. The process accor to claim 1, characterized in that the meltable processable polimepco material is passed through a plurality of extrusion orifices which are provided in the form of a spinneret extrusion die. . process accor to claim 1, characterized in that the cooling zone is provided as a cross flow cooling. The process accor to claim 1, characterized in that at least two spaced-out, drawn stretching rollers are rotated at a surface speed in the range of about 1,000 to 5,000 meters per minute. The process accor to claim 1, characterized in that the multi-filament spinning line following the passage through the pneumatic feed jet is collected on the surface of a continuous web which is provided in a spaced relation to the jet of pneumatic advance. 8. The process in accordance with the claim 1, characterized in that the yarn line of multiple filaments, when collected on the support, has a dTex per filament of approximately 1.1 to 22. 9. The process accor to claim 1, characterized in that the yarn line of multiple filaments It is formed mainly of polyethylene terephthalate and when it is collected on the support it has a dTex per filament of approximately 0.55 to 8.8. 10. The process accor to claim 1, characterized in that the spinning line of m tip is filaments isotactic polypropylene and when collected on the support has a dTex per filament of about 1.1 to 11. The process accor to claim 1, characterized in that the fabric, after its collection on the support, is fused in geometric figures when it forms the non-woven fabric made of fused filaments. 12. The process according to claim 1, characterized in that the fabric, after its collection on the support, is superficially fused when it forms the nonwoven fabric made of filaments fused together. 13. The process according to claim 1, characterized in that the nonwoven fabric made of fused filaments formed, has a weight of approximately 13.6 to 271.7 g / m. An apparatus for the production of a nonwoven fabric made of fused filaments, characterized in that it comprises in combination: (a) a plurality of holes for extrusion in the molten state, capable of forming a multi-filament spinning line, after the extrusion of a molten thermoplastic polymer material, (b) a cooling zone capable of carrying out the solidification of the molten, multi-filament thermoplastic polymer yarn line, after the melt extrusion thereof, (c) at least two driven drawing rollers, spaced, located downstream of the cooling zone, which are surrounded in areas where the multi-filament thermoplastic polymer yarn line would come into contact with the rollers, by a cover having an inlet end and an outlet end that is provided, such that the cover is capable of receiving the multiple filament thermoplastic polymer yarn line and the stretching rollers are capable of exerting a tensile force on the multi-filament thermoplastic polymer yarn line, to carry the stretching of the same adjacent to the extrusion holes, (d) a pneumatic advance, located at the outlet end of the cover, which is capable of assisting the contact of the multi-filament thermoplastic polymer yarn line with the spaced, driven stretch rollers and which is further capable of ejecting the multi-filament thermoplastic polymer yarn line into the direction of its length from the exit end of the cover, a sopor oca za or in a relation spaced below the jet of pneumatic advance, which is capable of receiving the line of thermoplastic polymer yarn of multiple filaments and facilitate the laying of the same to form a fabric and (f) means of bonding or adhesion, capable of joining or adhering the thermoplastic multi-filament polymer yarn line, next to the formation of the fabric to form a non-woven fabric made of fused filaments. The apparatus according to claim 14, characterized in that the plurality of holes (a) for melt extrusion are provided as a row for straight yarn extrusion. 16. The apparatus according to claim 14, characterized in that the cooling zone (b) is capable of providing cross-flow cooling, wherein a cooling gas collides with the molten, multi-filament thermoplastic polymer yarn line, immediately after extrusion in the molten state. The apparatus according to claim 14, characterized in that the cover identified in (c) includes polymeric edges that are capable of being positioned in close proximity to the stretching rollers, to facilitate a substantially complete wrapping of the stretching rollers in the areas where a multi-filament thermoplastic poly- meric material is wrapped or rolled over them and the polyme- quate edges are able to disintegrate easily as a powder, on contact with the stretching rollers. 18. The apparatus according to claim 14, characterized in that the support (e) is a continuous band. 19. The apparatus according to claim 14, characterized in that the joining means (f) are capable of forming a non-woven fabric made of filaments fused together, joined in geometric figures. 20. The apparatus according to claim 14, characterized in that the joining means (f) are capable of forming a non-woven fabric made of fused filaments joined together on the surface. SUMMARY OF THE INVENTION An improved process and apparatus for the formation of a fibrous non-woven fabric, made of fused filaments, suitable for use in non-woven end uses, is described. A melt-processable thermoplastic polyester material is extruded in the molten state to form a multi-filament spin line (2), cooled and wound around at least two driven stretch rollers (14, 16), spaced, which are surrounded by a cover (12), before harvesting to form a fabric (40) and joins to form a non-woven product made of fused filaments. The stretching rollers (14, 16) exert a tensile force on the multiple filament spinning line (2), to carry out the stretching of the melted, multiple filament spinning line (2) before solidification complete The cover (12) makes it possible to self-tension the spinning line (2) around the stretching rollers (14, 16). A pneumatic jet (32), located at the outlet end (24) of the cover, assists in the contact of the multiple filament spinning line (2) with the stretching rollers (14, 16) in order to facilitate the imposing a uniform tensile force and ejecting the yarn line (2) of multiple filaments, in the direction of its length, towards a support (38) where it is collected. The formation of a non-woven product, made of fused filaments, highly uniform, is made possible on an dited basis.