JP2020122256A - Nonwoven web - Google Patents

Abstract

To provide a nonwoven web.SOLUTION: A nonwoven web comprises a plurality of fibers made from molten polymer. The fiber has an average fiber diameter in the range from about 0.5 micron to about 50 micron, a basis weight of at least about 0.5 gsm, and a tensile strength measured in the longitudinal direction in the range from about 12 gf/gsm/cm nonwoven web width to about 100 gf/gsm/cm nonwoven web width.SELECTED DRAWING: Figure 1

Description

The present invention relates to nonwoven webs.

Meltblown fibers can be made with extremely small diameters ranging from 1 micrometer to 10 micrometers, which is extremely advantageous in making various nonwovens. However, meltblown fibers are relatively weak in strength. In contrast, spunbond fibers can be made to be very strong, but have very large diameters in the range of 15 to 50 micrometers. Fabrics made from spunbond tend to have low opacity and a rough surface because the fiber diameter is very large. In addition, spinning the thermoplastic resin through a multi-row spinneret (spinneret) according to the spinning technique taught in US Pat. ) And/or columns of filaments solidify rapidly, which is a great challenge. Due to this rapid solidification of the outer wax and/or outer column, the filaments tend to be larger in diameter and/or cause filament defects and rope defects in adjacent inner wax and/or inner columns. Tend to be.

US Pat. No. 5,476,616

To date, the problem is that we have not been able to find a way to extrude fine fibers with a diameter commensurate with the diameter of the meltblown fibers, but with the strength of spunbond fibers.

We have now invented a nonwoven web that solves this problem.

Briefly, the present invention relates to apparatus and methods for making nonwoven webs and the nonwoven web itself. An apparatus for making nonwoven webs has a die block with an inlet for receiving molten material, the inlet being in communication with the cavity. The die block further has a gas passage through which pressurized gas can be introduced. The gas passage has an inner diameter. An insert is positioned within the gas passage, the insert having an outer diameter rather than an inner diameter. The majority of the outer diameter is smaller than the inner diameter of the gas passage, thereby forming an air chamber between them. The apparatus further comprises a spinneret secured to the die block, the spinneret having a gas chamber isolated from the cavity. The spinneret further has a gas passage connecting the gas chamber to the gas passage. A plurality of nozzles and a plurality of stationary pins are fixed to the spinneret. The plurality of nozzles and the plurality of stationary pins are grouped into an array of rows and columns, the array having a perimeter. Each of the plurality of nozzles is connected to the cavity. The device further comprises a gas distribution plate fixed to the spinneret, a plurality of first, second and third openings being formed through the gas distribution plate. Each of the first openings encloses each of the nozzles, each of the second openings encloses each of the stationary pins, and each of the third openings encloses the first and second openings. It is located adjacent to the opening. The device further comprises an outer member fixed to the gas distribution plate. A plurality of first and second enlarged openings are formed through the outer member. Each of the first enlarged openings surrounds each of the nozzles, and each of the second enlarged openings surrounds each of the stationary pins. The array of nozzles and stationary pins has at least one row and at least one column configured with a second enlarged opening, which are located adjacent to the periphery of the array. The pressurized gas exits at a predetermined rate through both the first enlarged opening and the second enlarged opening. The molten material is extruded into filaments, each of which is wrapped by a pressurized gas to solidify and decay into a fibrous state. In addition, the entire circumference of the extruded filaments/fibers is surrounded by another pressurized gas curtain to isolate them from the surrounding ambient air, essentially a dual shroud system. Finally, the device has a moving or moving surface located downstream of the outer member, on which fibers are collected into a nonwoven web.

A method of making a nonwoven web comprises making a molten polymer and directing the molten polymer into a die block. The die block has a cavity and an inlet connected to the cavity through which the molten material is conveyed. The die block further has a gas passage formed therethrough for carrying a pressurized gas. The gas passage has an inner diameter. An insert is positioned within the gas passage. The insert has an inner diameter and an outer diameter. The majority of the outer diameter of the insert is smaller than the inner diameter of the gas passage, thereby forming an air chamber between them. The spinneret body is fixed to the die block. The spinneret body has a gas chamber and a gas passage connecting the gas chamber to the gas passage. The spinneret body has a plurality of nozzles and a plurality of stationary pins fixed to the nozzles, and the nozzles and the stationary pins are grouped into an array of rows and columns. There is. The array has a perimeter. A gas distribution plate is fixed to the spinneret body. A plurality of first, second and third openings are formed through the gas distribution plate. Each of the first openings encloses each of the nozzles, each of the second openings encloses each of the stationary pins, and each of the third openings encloses the first and second openings. It is located adjacent to the opening. The outer member is fixed to the gas distribution plate. A plurality of first and second enlarged openings are formed through the outer member. Each of the first enlarged openings surrounds each of the nozzles, and each of the second enlarged openings surrounds each of the stationary pins. An array of nozzles and stationary pins has at least one row and at least one column of second enlarged openings located adjacent the perimeter. The extruded filaments exiting each of the nozzles are wrapped by a pressurized gas to solidify and decay into fibers. In addition, the entire perimeter of the extruded filaments/fibers is forced out of each of the second enlarged openings to isolate these filaments/fibers from the surrounding ambient air, essentially the dual shroud system. Wrapped by pressurized gas. Finally, the fibers are collected on the surface that is moving to form the nonwoven web.

The nonwoven webs of the present invention have a plurality of fibers made of molten polymer, the fibers having an average fiber diameter in the range of about 0.5 micrometers to about 50 micrometers, at least per square meter. A basis weight of about 0.5 grams and a force of about 10 grams per square meter per square centimeter width of the nonwoven web (about 10 gf/gsm/cm nonwoven web width) (9,810 Newtons/[(kg/ m ² )×m non-woven web width]) to about 50 gf/gsm/cm non-woven web width (49,050 newtons/[(kg/m ² )×m non-woven web width]) It has the tensile strength measured at.

A general object of the present invention is to provide an apparatus for forming nonwoven webs. A particular object of the present invention is to provide a method of forming a nonwoven web and the nonwoven web itself.

Another object of the present invention is a non-woven web having fine fibers, each fiber having a diameter about the same as that of conventional meltblown fibers and having a strength comparable to spunbonded fabrics. The purpose is to provide a non-woven web.

Another object of the present invention is a nonwoven web comprising fine fibers, the fibers having a diameter in the range of about 0.5 micrometer to about 50 micrometers, a basis weight of at least about 0.5 gsm, and About 10 gf/gsm/cm non-woven web width (9,810 newtons/[(kg/m ² )×m non-woven web width]) to about 50 gf/gsm/cm non-woven web width (49,050 newtons/[( It is to provide a non-woven web characterized by having a tensile strength in the range of up to kg/m ² )×m non-woven web width]).

Yet another object of the present invention is to provide a die block, characterized in that the incoming pressurized gas passages are insulated from the rest of the die block, thereby allowing the use of lower temperature gases. To do.

Still further, an object of the present invention is a method utilizing a dual shroud system, wherein each extruded filament is wrapped by a pressurized gas when the filament is crystallized to be attenuated into a fiber state, It is to provide a method characterized in that all the filaments/fibers are wrapped with a pressurized gas to isolate the filaments/fibers from the surrounding ambient air.

Other objects and advantages of the present invention will be apparent to those of ordinary skill in the art in view of the following description and accompanying drawings.

1 is a schematic representation of manufacturing forming a nonwoven web. It is sectional drawing which shows the die block, the spinneret, and the external plate in the state fixed to each other. It is a longitudinal cross-sectional perspective view of a die block, and is a figure which shows a pair of gas passages. FIG. 6 is an end view of a nozzle surrounded by an opening. FIG. 7 is an end view of a stationary pin surrounded by an opening. FIG. 3 is a partially exploded view of a portion of the spinneret within the area designated by reference A in FIG. 2. FIG. 6 is a perspective view of an array of nozzles arranged in elongated rows vertically aligned in a short length column, two outer rows comprising a second opening, each of the second openings FIG. 3B shows a state in which a stationary pin is housed and three columns located adjacent to the ends of the array consist of a second opening, each of the second openings housing a stationary pin. FIG. 6 is a partial cross-sectional view of a portion of a spinneret body showing two outer rows and a second outer row having a second enlarged opening having a stationary pin fixed therein, and a plurality of nozzles having laterally outer rows. FIG. It is a front view of a gas distribution plate. It is a front view of an outer side member. 3 is a schematic illustration of another method of forming a nonwoven web. FIG. 3 is a pair of bar graphs comparing the difference in “fiber diameter distribution” for nonwoven webs made in accordance with the present invention and nonwoven webs made using the conventional meltblown process. FIG. 3 is a graphical comparison of machine direction (MD) tensile strength for conventional meltblown webs, conventional spunbond webs and nonwoven webs made in accordance with the present invention.

Definitions Nonwoven fabrics are sheets, webs or batts of natural and/or artificial fibers or filaments (excluding paper) which are not converted to the thread state and are bonded to each other by mechanical, hydrodynamic, thermal or chemical means. Is defined.

Spunmelt is a method in which fibers are spun from a molten polymer through a plurality of nozzles provided in a die head connected to one or more extruders. Spunmelt methods can include the methods of the invention referred to as meltblowing methods, spunbonding methods, and spunblowing methods.

The meltblown process is a process for producing extremely fine fibers with a diameter of less than about 10 micrometers, in which once the filament exits the nozzle, a high temperature, high velocity gas stream is used to attenuate multiple molten polymer streams. The attenuated fibers are then collected on a flat belt or dual drum collector. A typical melt blow die has about 35 nozzles per inch (0.0254 m) and a single row of spinnerets. A typical meltblown die uses two tilted air jets to damp the filaments.

The spunbond method is a method of directly producing a strong fibrous nonwoven web from a thermoplastic polymer by using low temperature, high velocity air to damp the spun filaments and quenching the fibers near the spinneret face. The individual fibers are then randomly laid down on a collection belt and transported to a bonder to provide additional strength and integrity to the web. Fiber sizes are typically less than 250 μm (micrometers) and average fiber sizes range from about 10 micrometers to about 50 micrometers. The fibers are very strong compared to meltblown fibers due to the molecular chain alignment or alignment achieved during the decay of the crystallization (solidification) filaments. A typical spunbond die has multiple rows of polymer holes and the polymer melt flow rate is typically less than about 500 grams/10 minutes.

The present invention is a hybrid method of a conventional meltblown method and a conventional spunbond method. The present invention bridges the gap between these two methods. The present invention is a spunbond method for attenuating and solidifying the spinning filaments, except that the nozzles and stationary pins are uniquely arranged to allow the realization of parallel gas jets surrounding the spinning filaments. A multi-row spinneret similar to the spinneret used is used. In the present invention, each extruded filament is wrapped with a pressurized gas, the temperature of which may be lower or higher than that of the polymer melt. In addition, the entire circumference of the filament is surrounded by a curtain of pressurized gas, essentially a dual shroud system.

An alternative embodiment of the present invention uses an aspirator (aspirator) to damp the molten filament into a fibrous state. Aspirators use a high velocity gas (air) that is directed parallel to the intrinsic filament flow direction, rather than directed at a steep tilt angle to the filament. The combination of these features produces fibers that have a small or thin diameter that is about the same as conventional meltblown fibers, yet are very strong, about the same as conventional spunbond fibers. The apparatus of the present invention has a melt flow rate of about 4 grams per 10 minutes (g/10 minutes) to about 6,000 g/10 minutes according to American Standard Test Method (ASTM) D1238 at 210° C. and 2.16 kg. Is very versatile and versatile in that it can accommodate both meltblown and spunbond polymer resins.

Apparatus Referring to FIG. 1, an apparatus 10 for producing a nonwoven web 12 is shown. The nonwoven web 12 should have high loft. Polymer resin 14 in the form of small solid pellets is placed in hopper 16 and then fed through conduit 18 to extruder 20. In the extruder 20, the polymer resin 14 is heated to a high temperature. The temperature will vary depending on the particular composition of the polymer and the melting temperature. Generally, the polymer resin 14 is heated to its melting temperature or higher. The heated polymer resin 14 is converted into a molten material (polymer) 22 (see FIG. 2), which is then passed through a conduit 24 to a die block 26 to which a spinneret body 52 is fixed.

The polymer resin 14 can vary in composition. The polymer resin may be thermoplastic. The polymer resin 14 is polyolefin, polyester, polyethylene terephthalate, polybutylene terephthalate, polycyclohexylene dimethylene terephthalate, polytrimethylene terephthalate, polymethyl methacrylate, polyamide, nylon, polyacrylic acid resin, polystyrene, polyvinyl, polytetrafluoroethylene, Ultra high molecular weight polyethylene, extremely high molecular weight polyethylene, high molecular weight polyethylene, polyether ether ketone, non-fibrous plasticized cellulose, polyethylene, polypropylene, polybutylene, polymethylpentene, low density polyethylene, linear low density polyethylene, high density polyethylene , Polystyrene, acrylonitrile-butadiene-styrene, styrene-acrylonitrile, styrene triblock copolymer, styrene tetrablock copolymer, styrene-butadiene, styrene-maleic anhydride, ethylene vinyl acetate, ethylene vinyl alcohol, polyvinyl chloride, cellulose acetate, cellulose acetate Selected from the group consisting of butyrate, plasticized cellulose, cellulose propionate, ethyl cellulose, natural fibers, any derivative thereof, any polymer blend thereof, any copolymer thereof or any combination thereof. good. In addition, the polymer resin 14 may be a biodegradable thermoplastic resin derived from natural sources, such as polylactic acid, poly-3-hydroxybutyrate, polyhydroxyalkanoate, or any blend, copolymer, polymer solution or combination. Good to be selected. One of ordinary skill in the chemical arts may be aware of other polymers that may also be used to form the nonwoven web 12. It should be understood that the nonwoven web 12 of the present invention is not limited to the polymers themselves described above.

The nonwoven web 12 can be made of a homopolymer. The nonwoven web 12 can be made of polypropylene. Alternatively, the nonwoven web 12 can be made of two or more polymers. The nonwoven web 12 may include bicomponent or bicomponent fibers, where the fibers have a sheath-core morphology, where the core is made of one polymer and the sheath around it is made of another polymer. To be Yet another option is to make the nonwoven web 12 of bicomponent fibers, where the fibers have an apposed configuration. One of ordinary skill in the art will be aware of various fiber designs that include two or more polymers.

It should be understood that the nonwoven web 12 may include additives that may be applied prior to or after collecting the fibers. Such additives include highly water-absorbing materials, absorbent particles, polymers, nanoparticles, abrasive particles, active particles, active compounds, ion exchange resins, zeolites, softeners, plasticizers, ceramic particle pigments, dyes, fragrances, aromas, Sustained release vesicles, binders, adhesives, adhesives, surface modifiers, lubricants, emulsifiers, vitamins, peroxides, antibacterial agents, deodorants, flame retardants, defoamers, antistatic agents, insecticides, Antifungal agents, degradants, stabilizers, conductivity modifiers, or any combination thereof are included, but are not limited to.

Referring to FIG. 2, a cross-sectional view of die block 26 and spinneret body 52 is shown. Molten material 22 enters die block 26 through inlet 28 that communicates with cavity 30. The cavity 30 may be an enlarged area that equalizes the molten material (polymer). The term "equalizing" means making uniform. Depending on the size of the die block 26, the cavity 30 may be several inches wide and up to several feet long (1 inch is 2.54 cm and 1 foot is 0.3048 m). ). Cavity 30 may house a polymer distribution plate and a filter screen (not shown).

2 and 3, the die block 26 has one or more gas passages 32 formed therein. A pair of gas passages 32, 32 are shown in FIGS. Each gas passage 32 has an inner diameter d. The inner diameter d may vary in size. The pressurized gas passing through each of the gas passages 32, 32 is typically pressurized air.

It should be understood that in FIG. 3 the pair of gas passages 32, 32 are offset from the inlet 28, so the inlet 28 is not visible in FIG.

Each of the pair of gas passages 32, 32 may vary in diameter, length and shape. Each of the pair of gas passages 32, 32 may be straight, curved, sloping, or have some other unique shape. It has been found that by positioning the hollow insert 34 in each of the pair of gas passages 32, 32, the temperature of the incoming gas can be well controlled. The term "gas" means a state of matter that is distinguished from solid and liquid states by its relatively low density and viscosity and its spontaneous tendency to become uniformly distributed throughout any container. That is, it means a substance in a gaseous state. In device 10, a pressurized gas, which may be air, is introduced into die block 26 and spinneret body 52. The term "air" means a colorless, odorless gaseous mixture containing primarily nitrogen (about 78%) and oxygen (about 21%) and small amounts of other gases.

The insert 34 may be a ceramic insert. The term "ceramic" refers to any of a variety of hard, brittle, heat and corrosion resistant materials made by shaping a non-metallic mineral, such as clay, and then baking it at high temperatures. I mean. Alternatively, the insert 34 may be constructed of various other refractory materials. Yet another option is to coat the insert 34 with a heat resistant coating, such as a ceramic coating. Also, the insert 34 may be coated with some other material having good thermal insulation.

As best shown in FIG. 3, each of the inserts 34, 34 has an inner or inner diameter d ₁ and an outer or outer diameter d ₂ . Desirably, the inner peripheral portion d ₁ is smooth. Inner diameter d ₁ may vary depending on the size of die block 26. One meter equals 39.37 inches. Typically, the inner diameter d ₁ is in the range of about 0.1 inch (0.00254 m) to about 1 inch (0.0254 m). Desirably, the inner circumference d ₁ is at least 0.25 inches (0.00635 m) in diameter. More preferably, the inner circumference d ₁ is at least 0.3 inches (0.00762 m) in diameter. Even more desirably, the inner circumference d ₁ is at least 0.4 inches (0.01016 m) in diameter. Most preferably, the inner diameter d ₁ is about 0.5 inch (0.0127 m).

Each insert 34 has a first end 36 and a second end 38. The first end 36 is spaced from the second end 38. The first end 36 is aligned with the outer surface 42 of the die block 26 and the second end 38 is aligned with the inner surface 40 of the die block 26. The first end 36 has an outwardly projecting flange 44 and the second end 38 also has an outwardly projecting flange 46. The term "flange" refers to a protruding rim, edge, rib or collar provided on, for example, a pipe shaft and used to reinforce one object, hold one object in place or attach one object to another. Means The structural shape of the flanges 44, 46 creates a physical chamber 48 in a machined boring hole 50 in the die block 26 within which each insert 34 is fitted. Each of the pair of inserts 34, 34 fits into each of the pair of boring holes 50, 50, respectively. The chambers 48, 48 are arranged between the inner peripheral portion d of each boring hole 50 and the outer peripheral portion d ₂ of each of the pair of inserts 34, 34. Each chamber 48 extends longitudinally along the portion of the insert 34 between the two flanges 44, 46. Desirably, each chamber 48 extends along a major portion of the outer circumference d ₂ of each of the pair of inserts 34, 34. Each chamber 48 may be filled with a gas, eg air. Each chamber 48 acts as an insulator that limits heat transfer from the hot die block 26 to the pressurized gas through the inner perimeter d ₁ of each of the pair of inserts 34, 34. Because of this, there are no cold spots in the die block 26. In addition, the hot die block 26 does not raise the temperature of the incoming pressurized gas being delivered to the spinneret body 52. The combination of the pair of inserts 34, 34 and the adjacent chambers 48, 48 allows the operator to pass through the die block 26 without significantly affecting the temperature of either the die block 26 or the incoming pressurized gas (air). The pressurized gas (air) can be directed. For this reason, very cold pressurized gas (air) can be utilized in the method of the invention. This cold pressurized gas (air) can promote crystallization of the fibers (solidification of the extruded filaments into the state of the fibers) and enhance the tensile properties of the fibers.

Still referring to FIG. 3, chambers 48, 48 may vary in size, shape and configuration. Desirably, each of the chambers 48, 48 has a height h that ranges from about 0.01 inch (0.000254 m) to about 0.3 inch (0.00762 m). More preferably, the height h of each chamber 48, 48 may range from about 0.05 inch (0.00127 m) to about 0.25 inch (0.00635 m). Even more desirably, the height h of each chamber 48, 48 may range from about 0.1 inch (0.00254 m) to about 0.2 inch (0.00508 m). Most preferably, the height h of each chamber 48, 48 is about 0.12 inches (0.0356 m) or greater.

The provision of chambers 48, 48 in combination with the materials of construction of the inserts 34, 34 or the coating material of the inserts 34, 34 allows the pressurized gas (air) delivered through the inserts 34, 34 to flow through the die block 26. There is no substantial heating due to the temperature. In other words, the inserts 34, 34 in combination with the chambers 48, 48 serve to provide adiabatic action and limit heat transfer.

It should be understood that the inner perimeter d of each of the boring holes 50, 50 may also be covered with a ceramic coating to provide another layer of insulation if desired.

The die block 26 is made of a metal or steel block that is a good conductor of heat. Also, due to the large mass of the die block 26, the die block 26 retains the heat carried therein. The temperature of the die block 26 is such that the heated cartage (not shown) prevents the molten material 22 (polymer) from flowing through the die block 26, and yet the polymer melt solidifies by cold ambient or process air. By doing so, it is increased above ambient temperature. The term "ambient temperature" means ambient temperature, eg room temperature. The melting temperatures of the various molten materials 22 (polymers) vary, but are typically above 100°C. For most polymers, the melting temperature may be as high as 200°C, 250°C, 300°C, 350°C, 400°C, or even higher. By insulating the incoming pressurized gas (air) from the high temperatures in the die block 26, the overall process can be well controlled, yet extruded filaments and fibers are produced that are extremely accurate in terms of composition, diameter and strength. can do.

Referring again to FIG. 2, the device 10 further comprises a spinneret body 52. The term "spinneret" means a device for making synthetic fibers consisting of plates provided with holes through which a plastic material (polymer) is extruded into filaments. The spinneret body 52 is fixed to the die block 26. The die block 26 and spinneret body 52 have essentially the same length and width. Usually, the periphery of each of the die block 26 and the spinneret body 52 is continuous. The die block 26 and the spinneret body 52 each have a rectangular shape as a whole. The spinneret body 52 has a length 1 (see FIG. 1) and a width w (see FIG. 2). The length l is longer than the width w. The spinneret body 52 has a gas chamber 54. One or more gas passages 56, 56 are formed in the spinneret body 52. A pair of gas passages 56, 56 are shown in FIG. 2, each gas passage being connected to a respective pair of gas passages 32, 32. A pair of gas passages 56, 56 connects the gas chamber 54 to the pair of gas passages 32, 32 so that pressurized gas (air) can be introduced into the gas chamber 54. Has become. A source of pressurized gas (air) is not shown in the drawings, but the equipment or equipment that produces the pressurized gas (air) is well known to those skilled in the art.

It should be appreciated that the gas chamber 54 is separate and independent of the cavity 30 formed in the die block 26. In other words, the gas chamber 54 is isolated from the low sun 30. The term "isolated" means separated or separated from another so as to be free from external influences, i.e. to mean thermal insulation. This means that the molten material 22 is not in contact with the pressurized gas (air) while the molten material 22 is inside the cavity 30.

It should be understood that the spinneret body 52 may be coated with a ceramic coating if desired.

The device 10 further includes a plurality of nozzles 58. The term "nozzle" means a protruding piece with an opening provided, for example, at the end of a hose to regulate and direct the flow of fluid or molten material. Each of the nozzles 58 is fixed to the spinneret body 52. Each nozzle 58 is spaced from an adjacent nozzle 58. The number of nozzles 58 in the spinneret body 52 may vary. The spinneret body 52 can have as few as 10 nozzles 58 to thousands of nozzles 58. For commercial size lines, the number of nozzles 58 in the spinneret body 52 may range from about 1,000 to about 10,000. Desirably, the spinneret body 52 has at least about 1,500 nozzles. More desirably, the spinneret body 52 has at least about 2,000 nozzles. Even more desirably, the spinneret body 52 has at least about 2,500 nozzles. Most desirably, the spinneret body 52 has 3,000 or more nozzles.

The nozzle 58 may vary in size. The size of the nozzle 58 may range from about 50 micrometers to about 1,000 micrometers. More desirably, the size of nozzle 58 may range from about 150 micrometers to about 700 micrometers. More desirably, the size of nozzle 58 may range from about 200 micrometers to about 600 micrometers. Nozzles of various sizes can be used, but generally speaking, all of the nozzles have the same size.

2, 4, and 6, each of the nozzles 58 may be made of metal, such as steel, stainless steel, metal alloys, ferrous metal, or the like. Desirably, each of the nozzles 58 is made of stainless steel. Each of the nozzles 58 is shown as an elongated hollow tube 60, see FIGS. 2 and 6 for this. The term "tube" means a hollow cylinder, in particular a hollow cylinder that carries a fluid or functions as a tool. Each of the hollow cylindrical tubes 60 is open at each end and has a central longitudinal axis and a uniquely shaped inner cross section. Desirably, the inner cross section of each tube 60 is circular in shape and is constant throughout its length. The length of each of the nozzles 58 may vary. Typically, the length of the nozzle 58 is in the range of about 0.5 inches (0.0127 m) to about 6 inches (0.1524 m).

It should be understood that the nozzle 58 can be of any geometric shape, but a circular shape is preferred.

Each of the nozzles 58 in the form of a hollow cylindrical tube 60 has an inner or inner diameter d ₃ and an outer or outer diameter d ₄ . The inner diameter d ₃ is good in the range of about 0.125 millimeters (mm) to about 1.25 mm. The outer diameter d ₄ of each nozzle 58 should be at least about 0.5 mm. Desirably, the outer diameter d ₄ of each nozzle 58 is in the range of about 0.5 mm to about 2.5 mm.

The molten material 22 (polymer) is extruded through the inner peripheral portion d ₃ of each nozzle 58. The back pressure on the molten material 22 (polymer) present in each of the hollow cylindrical tubes 60 should be equal to or above about 5 bar. The term "bar" means a unit of pressure equal to one million (10 ⁶ ) dynes per square centimeter. Desirably, the back pressure on the molten material 22 (polymer) present in each of the hollow cylindrical tubes 60 may be in the range of about 20 bar to about 200 bar, depending on the properties of the polymer and operating conditions. More desirably, the back pressure on the molten material 22 (polymer) present within each of the hollow cylindrical tubes 60 may be in the range of about 25 bar to about 150 bar. Even more desirably, the back pressure on the molten material 22 (polymer) present in each of the hollow cylindrical tubes 60 may be in the range of about 30 bar to about 100 bar.

Referring again to FIG. 2, the device 10 further includes a plurality of stationary pins 62. Each of the stationary pins 62 is an elongated solid member having a central longitudinal axis and an outer circumference or outer diameter d ₅ . Each of the stationary pins 62 is fixed to the spinneret body 52, and typically these stationary pins have approximately the same outer diameter as the polymer nozzle 58. The outer diameter d ₅ of each of the stationary pins 62 should remain constant throughout its length. The dimensions of the outer diameter d ₅ can vary. Desirably, the outer diameter d ₅ of each of the stationary pins 62 is at least about 0.25 mm. More desirably, the outer diameter d ₅ of each of the stationary pins 62 is at least about 0.5 mm. Even more desirably, the outer diameter d ₅ of each of the stationary pins 62 is at least about 0.6 mm. Most desirably, the outer diameter d ₅ of each of the stationary pins 62 is at least about 0.75 mm.

Referring now to FIGS. 7 and 8, nozzles 58 and stationary pins 62 are grouped into an array of rows 64 and columns 66. , The array has a perimeter 68. The term "array" means a systematic array. The number of rows 64 can vary, as can the number of columns 66. Typically, the number of waxes 64 will range from about 2 to about 50. Desirably, the number of braces 64 is in the range of about 3 to about 30. More desirably, the number of braces 64 is in the range of about 4 to about 25. Even more desirably, the number of braces 64 is in the range of about 4 to about 20. Most preferably, the number of braces 64 is in the range of about 5 to about 15.

Typically, the number of columns 66 will range from about 50 to about 500. Desirably, the number of columns 66 is in the range of about 60 to about 450. More desirably, the number of columns 66 is in the range of about 100 to about 300. Even more desirably, the number of columns 66 is in the range of about 150 to about 250. Most preferably, the number of columns 66 exceeds 200.

The spinneret body 52 has a nozzle density ranging from about 30 nozzles per centimeter to about 200 nozzles per centimeter. Desirably, the nozzle density is greater than 50 nozzles per centimeter. More desirably, the nozzle density is greater than 75 nozzles per centimeter. Even more desirably, the nozzle density is greater than 100 nozzles per centimeter. Most desirably, the nozzle density is greater than 150 nozzles per centimeter.

The polymer throughput through each nozzle 58 is expressed in "grams per hole per minute" (ghm). Polymer throughput through each nozzle 58 may range from about 0.01 ghm to about 4 ghm.

The finished diameter of each of the extruded and dampened fibers is less than or equal to about 50 micrometers. The average fiber diameter is from about 0.5 micrometer to about 50 micrometers with a standard deviation of greater than 0.5 micrometers. Desirably, the average fiber diameter is from about 1 micrometer to about 50 micrometers and the standard deviation is greater than 0.5 micrometers. More desirably, the average fiber diameter is from about 1 micrometer to about 30 micrometers and the standard deviation is greater than 0.5 micrometers. Even more desirably, the average fiber size is from about 1 micrometer to about 20 micrometers and the standard deviation is greater than 0.5 micrometers. Most desirably, the average fiber size is from about 1 micrometer to about 10 micrometers and the standard deviation is greater than 0.5 micrometers.

Perimeter 68 is shown by lines extending along the exterior of nozzles 58 and stationary pins 62. Row 64 is shown as a long line extending horizontally within device 10, and column 66 is short in length and vertically aligned with row 64. The term "perpendicular" means intersecting at a right angle (90°) or forming a right angle (90°). Although row 64 and column 66 are shown as vertically aligned with each other, it is certain that various angular alignments may be used if desired. Rows 64 and columns 66 are also shown as arranged in parallel rows 64 and parallel columns 66. The term "parallel" means equal separations no matter where they are taken. However, the rows 64 and/or columns 66 may be staggered if desired. The number of rows 64 may vary and so may the number of columns 66.

It is noted in FIG. 7 that the two outer rows 64, 64 located adjacent the two longitudinal sides of the perimeter 68 of the row 64 and the array of columns 66 do not include the nozzle 58. In addition, the three columns 66 located at the ends of the array also do not include any nozzles 58. If desired, stationary pins 62 may be utilized in the same number of rows 64 and columns 66 located adjacent perimeter 68. Typically, only one or two rows adjacent the outer perimeter 68 of the array will have no nozzles 58, and about 1 to about 50 of columns 66 may have no nozzles 58. The exact number of columns 66 that do not include nozzles 58 will depend in part on the overall size of the spinneret body 52. The reason for not placing the nozzle 58 in such a row 64 and column 66 is simply more than a rectangular outer member 78 (see FIG. 2) having about 12 rows 64 and about 150 or more columns 66. Column 66 exists. Therefore, many nozzles 58 can be eliminated from the columns 66 rather than from the rows 64. In addition, by narrowing the width of the array of nozzles 58 in the spinneret body 52, a good constant temperature can be maintained between the plurality of nozzles 58 being utilized.

As mentioned above, the total number of nozzles 58 and stationary pins 62 that can be secured to the spinneret body 52 can vary. The larger the size of the spinneret body 52, the greater the number of nozzles 58 and stationary pins 62 it can support. With respect to a representative commercial spinneret body 52, the spinneret body has several braces 64 and more columns 66. The number of waxes 64 may vary, but generally ranges from about 4 to about 20. The number of columns 66 may also vary, but generally ranges from about 50 to about 500. Desirably, the commercial size spinneret body 52 has about 8 to about 16 rows and about 100 to about 300 columns. For example, a spinneret body with a total of 2,496 combined nozzles 58 and stationary pins 62 can have 12 rows 64 and 208 columns 66.

2 and 9, the device 10 further comprises a gas distribution plate 70 secured to the spinneret body 52. The gas distribution plate 70 functions to distribute the pressurized gas (air) evenly around each of the nozzles 58 to ensure proper filament attenuation. The gas distribution plate 70 may vary in thickness, morphology and its constituent materials. Desirably, the gas distribution plate 70 is constructed of metal or steel. More preferably, the gas distribution plate 70 is constructed of stainless steel. A large number of openings are formed through the gas distribution plate 70. The plurality of openings include a plurality of first openings 72 through which a plurality of nozzles 58 can pass, a plurality of second openings 74 through which a plurality of stationary pins 62 can be inserted, and It includes a plurality of third openings 76 through which pressurized gas (air) can pass. The exact number of first, second and third openings 72, 74, 76 may vary depending on the size of the spinneret body 52 and the total number of nozzles 58 and stationary pins 62 utilized. The first and second openings 72,74 must align with an array of nozzles 58 and stationary pins 62 secured to the spinneret body 52. No extra or unused first and second openings 72, 74 should be formed through the gas distribution plate 70.

The plurality of first, second and third openings 72, 74, 76 are all shown as circular openings with certain patents. As a result, each of the plurality of nozzles 58 and each of the plurality of stationary pins 62 has a circular outer peripheral portion. The geometry of the third opening 76 need not be circular if desired. However, it is very cost-effective to form a circular hole rather than some other shape, so from a practical point of view, the third opening 76 is also likely to have a circular outer perimeter. Will be in

Each of the plurality of first openings 72 is sized and shaped to match or be slightly larger than the outer diameter d ₄ of the plurality of nozzles 58. An interference fit, a slip fit, or a pressure fit may be utilized to hold the plurality of nozzles 58 in the set array. Each of the plurality of second openings 74 is sized and shaped to match or be slightly larger than the outer diameter d ₅ of the plurality of stationary pins 62. Also in this case, interference fit, slip fit, or pressure fit may be used to hold the plurality of stationary pins 62 in the set arrangement state. Each of the plurality of third openings 76 is sized and shaped to allow a suitable amount of pressurized gas (air) to pass through the openings. The amount of pressurized gas (air) required depends on many factors, such as the composition of the molten material 22 (polymer) to be extruded, the number of nozzles 58 and stationary pins 62 present, the inner diameter d ₃ of each of the nozzles 58, the nozzles. It can be calculated based on the flow rate of the molten material 22 (polymer) through each of the 58, the velocity of the pressurized gas (air) through the gas distribution plate 70, etc. The term "velocity" means the speed or speed of exercise, and the speed. A person skilled in the art can easily calculate the amount of pressurized gas (air) required, its speed and the temperature which is advantageous for operating the device 10 at maximum speed.

Still referring to FIG. 9, it can be clearly seen that the first and second openings 72, 74 may be of the same diameter. As a modification, the diameter of the first opening 72 may be set smaller or larger than the diameter of the second opening 74. When the outer diameter d ₄ of each of the plurality of nozzles 58 is the same as the outer diameter d ₅ of each of the plurality of stationary pins 62, the diameter of each of the first openings 72 is equal to the second opening 74. Would be equal to the diameter of each.

Also, in FIG. 9, it is noticed that all the second openings 74 are arranged around the outer periphery (hereinafter, also referred to as “outer circumference”) 68 of the plurality of first openings 72. .. The term "perimeter" means the lines that form the boundaries of a region, and the lines, or perimeters. The reason for this arrangement is that it provides a second shroud or curtain of pressurized gas (air) that protects the extruded filaments from the surrounding ambient air. This is a unique feature of the present invention.

Similarly, it is clearly seen that each of the third openings 76 is smaller than the outer diameter of either the first opening 72 or the second opening 74. However, when it is desired to set the outer diameter of each of the third openings 76 to be larger than or equal to the outer diameters d ₄ and d ₅ of each of the first and second openings 72 and 74. This can be easily achieved, especially when a small diameter polymer nozzle 58 is used. One disadvantage of having a larger third opening 76 is that the rows 64 and columns 66 must be further separated from each other. This limits the total number of nozzles 58 and stationary pins 62 that can be fixed to the spinneret body 52.

Still referring to FIG. 9, it can be clearly seen that four of the third openings 76 are positioned adjacent each of the first and second openings 72,74. The exact number of third openings 76 associated with each of the first and second openings 72, 74 may vary. Similarly, the alignment and angular spacing of the third openings 76 with respect to each of the first and second openings 72, 74 may also vary. Moreover, the distance that each third opening 76 is separated from the first and second openings 72, 74 may also vary.

It should be appreciated that the gas distribution plate 70 may be coated with a ceramic coating if desired.

2 and 10, the device 10 further includes an outer member or plate 78. The outer member 78 is secured to the gas distribution plate 70 such that it is spaced from the spinneret body 52. The outer member 78 functions to form an annular pressurized gas (air) channel around each of the nozzles 58. The outer plate 78 may vary in thickness, morphology and its constituent materials. Desirably, the outer plate 78 is constructed of metal or steel. More preferably, the outer plate 78 is constructed of stainless steel. A number of openings are formed through the outer plate 78, some of which are first enlarged openings 80 through which one of the nozzles 58 passes and the remaining openings are of the stationary pin 62. It is a second enlarged opening portion 82 in which one of them is contained. Each of the first enlarged openings 80 receives a nozzle 58 and each of the second enlarged openings 82 receives a stationary pin 62.

It should be appreciated that the outer member 78 may be coated with a ceramic coating if desired.

With reference to FIG. 10, it can be clearly seen that all the second enlarged openings 82 are arranged around the outer circumference 84 of the plurality of first enlarged openings 80. The reason for this arrangement is that it provides a shroud and shroud around the perimeter 84 of the plurality of nozzles 58 and prevents ambient ambient air from contacting the extruded filaments, which results in faster filaments. Do not cool too much.

Referring back to FIGS. 4 and 5, it is also possible that each of the first enlarged openings 80 has an inner diameter d ₆ and each of the second enlarged openings 82 has an inner diameter d _7. Also noticed. The diameter d ₆ of the first enlarged opening 80 may be equal to the diameter d ₇ of the second enlarged opening 82. As a variant, the diameter d ₆ of the first enlarged opening 80 may be smaller than or larger than the diameter d _{7 of} the second enlarged opening 82.

Referring to FIG. 10, the diameter d ₆ of each of the first enlarged openings 80 matches the diameter d ₇ of each of the second enlarged openings 82. Further, comparing the first enlarged opening 72 and the second opening 74 shown in FIG. 9 with the first opening 80 and the second opening 82 shown in FIG. 10, respectively, It can be seen that the first enlarged opening 80 and the second enlarged opening 82 have a very large diameter. The reason for this is that pressurized gas (air) exits through each of the first enlarged opening 80 and the second enlarged opening 82 and creates a shroud around each of the nozzles 58 and around each of the stationary pins 62. To form. The term "shroud" means something that is hidden, protected or obstructed. When the first enlarged opening 80 and the second enlarged opening 82 are circular, a shroud of pressurized gas (air) completely surrounds each of the nozzles 58 and each of the stationary pins 62 (360°). be able to.

Referring again to FIG. 7, it can be seen that each of the plurality of nozzles 58 is centered within each of the first enlarged openings 80. Similarly, each of the plurality of stationary pins 62 is centered within each of the second enlarged openings 82. The reason for this is that the shroud of pressurized gas (air) is located evenly distributed around the outer circumference of each of the nozzles 58 and along the outer circumference of each of the stationary pins 62. Pressurized gas (air) surrounds each of the nozzles 58 and helps the extruded molten material 22 (polymer) to solidify and decay. In addition, within the array of nozzles 58 and stationary pins 62, at least one row 64 and at least one column 66 have a second enlarged opening 82 adjacent the perimeter 84 of the first enlarged opening 80. It can be seen that it is arranged to be located. This means that at least the outer row 64 and at least the outermost column 66 located adjacent to the four sides or sides of the outer plate 78 have only the second enlarged opening 82. The reason for this configuration is that it provides a shroud or curtain of pressurized gas (air) around all of the plurality of nozzles 58. This second shroud of pressurized gas (air) is intended to limit or prevent the rapid solidification of the filaments that occurs when ambient air around the facility housing the extruder 20 contacts the filaments. Become.

Referring again to FIG. 2, the molten material 22 (polymer) is extruded as the pressurized gas exits each of the first enlarged openings 80 adjacent the plurality of nozzles 58 at a predetermined rate. Becomes the state of the filament 86. Each filament 86 is prevented from being roped from the adjacent filament 86 by being surrounded by the surrounding pressurized gas. The term "filament" means a fine or thin spun material that is still in the semi-softened state. With this configuration, contact between adjacent filaments 86, 86 is prevented. In addition, the pressurized gas (air) exiting each of the plurality of second enlarged openings 82 forms a shroud around all of the extruded filaments 86. This second shroud protects the semi-molten filaments 86,86 from the surrounding ambient air and slows the cooling of the filaments 86,86. By lengthening the cooling time of each of the filaments 86, smaller diameter fibers 98 can be obtained and the characteristics of each fiber 98 can be accurately controlled. This feature of using a double fiber shroud plus a second fiber damping stage using an aspirator described below is very unique.

Still referring to FIGS. 2 and 7, the device 10 further includes a pair of cover strips 88, 88 secured to the outer member 78. Each of the pair of cover strips 88, 88 comprises a separate member spaced from the other members. Alternatively, the pair of cover strips 88, 88 may be made as a single piece. Each of the pair of cover strips 88, 88 is shown as having an outer surface 90, 90. Each of the pair of cover strips 88, 88 extends along the length 1 of the spinneret body 52. As shown, each of the pair of cover strips 88, 88 are aligned parallel to each other. Each of the outer surfaces 90, 90 may have a beveled portion 92. The diagonal portion 92 extends downward and inward from the outer surface 90. The term "diagonal" means the angle or slope at which a line or surface intersects another line or surface at any angle other than 90°. The beveled surfaces, ie the bevels 92, 92, extend longitudinally along the length 1 of the spinneret body 52. The angle α of each of the slopes 92, 92 may vary. Desirably, each bevel 92, 92 is formed at an angle α (see FIG. 2) which may range from about 15° to about 75°.

Still referring to FIG. 2, the pair of cover strips 88, 88 may be made of metal, such as steel, stainless steel, metal alloys, ferrous metal, or the like. Desirably, the pair of cover strips 88,88 is made of stainless steel. The pair of cover strips 88, 88 facilitates the flow of ambient air around the pressurized gas exiting at least some of the second enlarged openings 82. The pair of cover strips 88, 88 directs a flow of ambient air around it around the lower portion of the outer member 78, causing the air to move in the direction indicated by arrows 94, 94. The surrounding ambient air follows the direction of the slopes 92, 92 and is then bent downward by the outflow pressurizing gas (air) that is violently exiting the second enlarged opening portion 82 from the plurality of nozzles 58. Can be kept away. Outflowing pressurized gas (air) comes from the gas chamber 54 through a third opening 76 formed in the gas distribution plate 70 and a second enlarged opening 82 formed in the outer member 78. ..

The pair of cover strips 88, 88 also serves to redistribute the clamping force exerted on the outer member 78 and the gas distribution plate 70 to secure them to the spinneret body 52. The pair of cover strips 88, 88 also serves to protect the nozzle 58 from entrained air in the chamber, which may be retracted from the sides and may have a cooling effect on the outer wax.

Referring now to FIGS. 2 and 6, the molten material 22 (polymer) present in the cavity 30 of the die block 26 is forced downward through a plurality of nozzles 58 and through a hollow cylindrical tube 60. Flowing. Each nozzle 58 has a distal end 96 that lies below the plane of the outer member 78. Desirably, each end 96 lies below the plane of the outer surface 90 of the pair of cover strips 88,88. Each nozzle 58 extends by a vertical distance d ₈ beyond the first enlarged openings 80 downward, as will see FIG. 6. The distance d ₈ can vary. Preferably, the distance d ₈ should be at least about 1 mm. More desirably, the distance d ₈ is at least about 2 mm. Even more desirably, the distance d ₈ is at least about 3 mm. Most desirably, the distance d ₈ is at least about 5 mm.

Referring to FIG. 2, the molten material 22 (polymer) exits each of the plurality of nozzles 58 as a filament 86. Each of the filaments 88 is isolated by the pressurized gas (air) exiting the first enlarged opening 80. This pressurized gas (air) provides a shroud or veil that limits the filaments 86 from contacting, touching and/or binding adjacent filaments 86 to form ropes and/or bundles. The term "veil" means something that is concealed, separated or obscured like a curtain. The speed and pressure at which the filament 86 exits the plurality of nozzles 58 may be varied to suit its equipment and to form fibers 98 (see FIG. 1), such speed and pressure depending on certain fiber criteria. For example, it satisfies a specific diameter, composition, strength and the like.

The temperature of the pressurized gas (air) used in damping the filament 86 at or near the nozzle 58 may be lower than the melting temperature of the passing filament 86, and The temperature may be the same or higher. Desirably, the temperature of the pressurized gas (air) used in surrounding and attenuating filament 86 at or near nozzle 58 ranges from about 0° C. to about 250° C. above the melting temperature of filament 86. Low or high temperature. More desirably, the temperature of the pressurized gas (air) used in surrounding and attenuating filament 86 at or near nozzle 58 ranges from about 0° C. to about 200° C. above the melting temperature of filament 86. Low or high temperature conditions for Even more desirably, the temperature of the pressurized gas (air) used in surrounding and attenuating filament 86 at or near nozzle 58 is from about 0° C. to about 150° C. above the melting temperature of filament 86. Low or high temperature over range. Most desirably, the temperature of the pressurized gas (air) used in surrounding and attenuating filament 86 at or near nozzle 58 ranges from about 0° C. to about 100° C. above the melting temperature of filament 86. Low or high temperature conditions for

The pressurized gas (air) discharged through the plurality of second openings 82 forms a pressurized gas (air) flow, and the pressurized gas (air) flow includes a plurality of filaments. Limit or prevent 86 from contacting the surrounding ambient air. Desirably, the pressurized gas (air) is capable of forming an envelope, shroud or curtain around the entire circumference of or around the entire number of filaments 86. The speed and pressure at which the filament 86 exits the plurality of nozzles 58 may be varied to suit its equipment and to form fibers 98 (see FIG. 1), such speed and pressure depending on certain fiber criteria. For example, it satisfies a specific diameter, composition, strength and the like.

Referring now to FIG. 11, an alternative device 10' having an aspirator 100 is shown. The aspirator 100 is located downstream of the distal end 96 of each of the nozzles 58. The term "aspirator" means a device that produces a high velocity gas (air) jet for dragging and damping the filament 86. The aspirator 100 is vertically aligned with the downstream side of the plurality of filaments 86 so that the plurality of filaments 86 can easily pass through the aspirator. Pressurized gas (air) is introduced into the aspirator 100 via one or more conduits 102. A pair of conduits 102, 102 is shown in FIG. The number of conduits 102 may vary from one to several. The incoming pressurized gas (air) flowing into the aspirator 100 is aligned parallel to the flow direction of the filament 86. This parallel gas (air) flow characteristic is that the parallel gas (air) jet exerts a drag force (fluid resistance) on the filament 86 so that the filament is placed under tension, and as a result, the filament 86 Is attracted to the state of the fiber 98, which is important. The incoming pressurized air to the aspirator 100 may be cooled, brought to room temperature or heated. Typically, incoming air is at or slightly above room temperature. When the filament 86 is passing through the aspirator 100, it is at least twice the velocity of the pressurized gas (air) exiting the plurality of first enlarged openings 80 and the second enlarged openings 82. The fibers 98 are attenuated by the pressurized gas (air) flowing through the aspirator 100 at a certain velocity. The term "damping" means elongating, thinning, or reducing in diameter. Desirably, the pressurized gas (air) used to damp the filaments 86 into the state of the fibers 98 is the pressurized gas (air) exiting the plurality of first and second enlarged openings 80, 82. It is moving at a speed that is at least 2.5 times the speed of (air). More preferably, the pressurized gas (air) used to damp the filament 86 into the fiber 98 is the pressurized gas exiting the plurality of first and second enlarged openings 80, 82. It is moving at a speed that is at least 5 times the speed of (air). Even more preferably, the pressurized gas (air) used to damp the filaments 86 into the fibers 98 pressurizes out of the plurality of first and second enlarged openings 80, 82. It is moving at a speed that is at least 10 times the speed of gas (air). Most preferably, the pressurized gas (air) used to damp the filament 86 into the fiber 98 is the pressurized gas exiting the plurality of first and second enlarged openings 80,82. It is moving at a speed that is more than 10 times the speed of (air). For example, the pressurized air used to damp the filament 86 into the state of the fibers 98 is at least about 50 meters per second (m/s), about 100 m/s, about 200 m/s, about 250 m/s, about 250 m/s. It is preferable to have a speed of 300 m/s, about 400 m/s or more.

The aspirator 100 functions as a second step in which the filament 86 is dampened so that it has approximately the same strength characteristics as fibers formed using conventional spunbond technology.

Referring back to FIG. 1, with no aspirator 100, slightly heated gas (air) to achieve high fiber attenuation at or near the end 96 of each of the nozzles 58. It should be noted that) is used. The fibers 98 made tend to be weaker than conventional spunbond fibers, but still tend to be much stronger than conventional meltblown fibers. This is especially true when the temperature of the pressurized gas (air) is about 50°C to about 100°C below the polymer melting temperature. The apparatus and methods of the present invention taught herein are extremely versatile and easy to tailor to make spunmelt fibers 98 with a wide range of properties. Such properties bridge the gap between conventional meltblown fibers and conventional spunbond fibers.

Referring again to FIG. 11, the number of fibers 98 exiting the aspirator 100 is equal to the number of filaments 86 entering the aspirator 100. However, the fibers 98 will have a smaller diameter than the diameter of each filament 86. In addition, the fibers 98 are generally stronger than the filaments 86. The diameter of each fiber 98 will be determined in part by the amount by which each filament 86 is attenuated within the aspirator 100. As the fibers 98 exit the aspirator 100, they are directed downwardly and collected on a moving surface (movable surface) 104.

Referring to FIGS. 1 and 11, the moveable surface 104 can be of various designs and configurations. For example, the moveable surface 104 may be a moveable closed loop forming wire 106 attached to and supported by two or more rollers 108. One of the rollers 108 may be a drive roller. Four rollers 108 are shown in FIGS. The movable surface 104 can rotate clockwise or counterclockwise. Alternatively, the movable surface 104 may be a conveyor belt, a rotatable drum, a forming drum, a dual drum collector, or known to those skilled in the art. It may be any other known mechanism.

The moveable surface 104 can be operated at room temperature, especially if the forming wire 106 or the conveyor belt is made of polyethylene terephthalate (PET) material. However, if the moveable surface 104 is made of metal or steel wire or covered with a metal belt, the moveable surface may be slightly modified to provide a particular texture or pattern that may enhance the properties of the nonwoven web 12. It is good to heat.

The movable surface 104 can move at various speeds, which can affect the composition, density, integrity, etc. of the finished nonwoven web 12. For example, increasing the speed of the moving surface 104 reduces the loft or thickness of the nonwoven web 12.

Still referring to FIGS. 1 and 11, device 10 or device 10 ′ further includes a vacuum chamber 110 positioned adjacent movable surface 104. As shown, the vacuum chamber 110 is positioned below the forming wire 106. The vacuum chamber 110 applies a vacuum or suction to the plurality of randomly assembled fibers 98 forming the nonwoven web 12. This vacuum pulls process gas (air) and surrounding ambient air away from the nonwoven web 12 and further limits or prevents the fibers 98 from flying around, thereby increasing the uniformity of the nonwoven web 12. Various types of vacuum chamber 110 can be used. The amount of vacuum applied may be varied to suit particular needs. Those skilled in the art are familiar with the types of vacuum equipment that can perform this function.

A bonder 112 is provided on the downstream side of the vacuum chamber 110. The bonder 112 may vary in design. The bonder 112 may be a mechanical bonder, a hydrodynamic bonder, a thermal bonder, a chemical bonder, or the like. The bonder 112 is optional, but for most non-woven webs 12 made of extremely thin and randomly arranged fibers, the bonding step provides additional strength and additional integrity. When utilizing the bonder 112, the bonder enhances the integrity of the nonwoven web 12 by forming spot bonds, point bonds, zone bonds, and the like.

It should be understood that the nonwoven web 12 may be subjected to other mechanical or chemical treatments if desired. For example, the nonwoven web 12 may be hydroentangled, perforated, cut, slit, perforated, punched, embossed, The nonwoven web may be printed, coated, or otherwise processed. After the bonder 112, the nonwoven web 12 may be wound onto a supply roll 114 if other processing is not desired. The cutter 116 can be used to cut, divide, cut, or slit the nonwoven web 12 into suitable lengths and/or widths.

Referring again to FIG. 1, the measured distance d ₉ from the distal tip 96 of each of the nozzles 58 to the movable surface 104 is shown. This distance d ₉ is referred to in the art as the “die to collector distance” (DCD). This DCD depends on the type of equipment used, the type of fibers 98 to be formed, the operating conditions of the device 10 or 10', the polymeric material 22 (polymer) to be extruded, the properties of the finished nonwoven web 12, etc. Can be various. Generally speaking, the DCD may range from about 10 centimeters (cm) ((0.1 m)) to about 150 cm (1.5 m). Desirably, the DCD is in the range of about 20 centimeters (cm) ((0.2 m)) to about 125 cm (1.25 m).

Method A method or process for forming the nonwoven web 12 will be described with reference to FIGS. 1, 2 and 11. The method includes forming a molten material 22 (polymer) and directing the molten material (polymer) through a die block 26. The molten material 22 (polymer) may be a homopolymer or two different polymers, each polymer being directed to a particular group of nozzles 58. Desirably, the molten material 22 (polymer) is polypropylene. The molten material 22 (polymer) is heated upstream of the die block 26, typically in the extruder 20 to a temperature of at least about 170°C. The die block 26 has a cavity 30 and an inlet 28 connected to the cavity 30. The inlet 28 carries the molten material 22 into the die block 26. Further, one or more gas passages 32, 32 for carrying the pressurized gas (air) to the spinneret body 52 are formed through the die block 26. Each of the gas passages 32, 32 (two shown) has an inner diameter d. An insert 34 is positioned within each of the gas passages 32,32. Each insert 34, 34 has an inner circumference or inner diameter d ₁ and an outer circumference or outer diameter d ₂ . The majority of the outer diameter d ₂ of each insert 34, 34 is smaller than the inner diameter d of each of the gas passages 32, 32, thereby forming a chamber 48 therebetween. The spinneret body 52 is fixed to the die block 26. The spinneret body 52 has a gas chamber 54 and one or more gas passages 56, 56 (two shown) that connect the gas chamber 54 to the gas passages 32, 32. Connected to. The spinneret body 52 has a plurality of nozzles 58 and a plurality of stationary pins 62 fixed to these nozzles, and the plurality of nozzles 58 and the plurality of stationary pins 62 include a plurality of rows 64 and a plurality of columns 66. Grouped into an array of arrays, the arrays having a perimeter 68.

The gas distribution plate 70 is fixed to the spinneret body 52. A plurality of first openings 72, second openings 74 and third openings 76 are formed through the gas distribution plate 70. Each of the first openings 72 receives each of the nozzles 58, each of the second openings 74 receives each of the stationary pins 62, and each of the third openings 76 receives the first. It is located adjacent to the opening 72 and the second opening 74.

The outer member 78 is secured to the gas distribution plate 70 such that the outer member 78 is spaced from the spinneret body 52. A plurality of first enlarged openings 80 and second enlarged openings 82 are formed through the outer member 78. Each of the first enlarged openings 80 surrounds each of the nozzles 58, and each of the second enlarged openings 82 surrounds each of the stationary pins 62. The array of nozzles 58 and stationary pins 62 has at least one row 64 and at least one column 66, which are located adjacent a perimeter 68 made up of a second enlarged opening 82. ..

The method further includes directing pressurized gas (air) through a plurality of first, second and third openings 72,74,76 formed in the gas distribution plate 70. The molten material 22 (polymer) is extruded through each of the nozzles 58 to form multiple filaments 86. Next, at least a portion of each of the multiple filaments 86 is surrounded by a pressurized gas being released at a predetermined rate through a first enlarged opening 80 formed in the outer member 78. The pressurized gas (air) exiting the second enlarged opening 82 formed in the outer member 78 is used to isolate all of the filaments 86 from the surrounding ambient air.

As the filaments 86 are extruded from each end 96 of the nozzle 58, they begin to solidify and are attenuated by the outflowing pressurized gas (air) into fibers 98. The optional second damping stage can be achieved with the aspirator 100, see FIG. When using the aspirator 100, the pressurized gas (air) in the aspirator 100 is at least twice as fast as the velocity of the pressurized gas exiting the first enlarged opening 80 and the second enlarged opening 82 (2 (More than double) speed. Desirably, the pressurized gas (air) in the aspirator 100 has a velocity that is at least five times the velocity of the pressurized gas exiting the first enlarged opening 80 and the second enlarged opening 82. More desirably, the pressurized gas (air) in the aspirator 100 has a velocity that is at least 10 times the velocity of the pressurized gas exiting the first enlarged opening 80 and the second enlarged opening 82. The filament 86 is dampened by a pressurized gas (air) that is directed essentially parallel to the flow direction of the filament 86. This is important because the dampening gas (air) is steered to the filament in other ways, especially in the conventional spunbond method. By keeping the dampening gas (air) essentially parallel to the direction of flow of the filament 86, multiple rows and columns of the filament 86 can be damped to a fiber 98 with unique properties and characteristics. .. Two of these unique properties include the ability to form small diameter or fine fibers 98 and the ability to form fibers 98 that are significantly stronger than conventional meltblown fibers. The fibers 98 are usually extruded as continuous fibers.

The fibers 98 are collected on the moving surface 104 to form the nonwoven web 12. The movable surface 104 may be the forming wire 106, a conveyor belt, a rotating drum, a drum type collector, a dual drum type collector, or the like.

The method applies a vacuum to the nonwoven web 12 while it is positioned on the moving surface 104 to remove the process gas and surrounding ambient air and to limit the fibers 98 from flying around, thereby causing the web to fly. May be further included. The vacuum may be provided by a vacuum chamber 110 located adjacent to the moving surface 104. Desirably, the vacuum chamber 110 is located below the moving surface 104.

The method may further include the step of joining the nonwoven webs 12. The bonder 112 may be located downstream of the vacuum chamber 110 or downstream of where the fibers 98 contact the moving surface 104. The bonder 112 functions to combine individual spots, zones, lines, regions, etc. of the nonwoven web 12 to enhance the integrity of the nonwoven web 12. The cutter 116 is preferably arranged on the downstream side of the bonder 112. The cutter 116 serves to cut, cut, slit or separate one section of the nonwoven web 12 from an adjacent section. The cutter 116 may be any type or type of cutting mechanism known to those of ordinary skill in the art.

Finally, there is the step of winding the finished nonwoven web 12 onto a supply roll 114 so that the nonwoven web 12 can be transported to a manufacturing site or location where the nonwoven web 12 is available. Is good. The nonwoven web 12 can be used in a variety of products and for many applications. Fine diameter fibers with good strength properties are particularly desirable for use in various absorbent products such as diapers, sanitary napkins, panty liners, training pants, incontinence garments and the like. Fine diameter fibers with good strength characteristics can be used for sound insulation, heat insulation, wipes, etc. The fibers 98 can also be used in various products.

Nonwoven Web The nonwoven web 12 produced by the apparatus 10 described above comprises a plurality of fibers 98 made of a molten material 22 (polymer). Desirably, the molten material 22 (polymer) is a homopolymer. More desirably, the molten material 22 (polymer) is polypropylene. Optionally, the nonwoven web 12 can be formed of two or more different polymeric resins. Additionally, the nonwoven web 12 can include bicomponent fibers.

The nonwoven web 12 has an average fiber diameter in the range of about 0.5 micrometer to about 50 micrometers. Desirably, the average fiber diameter is in the range of about 1 micrometer to about 30 micrometers. More desirably, the average fiber diameter is in the range of about 1 micrometer to about 20 micrometers. Even more desirably, the average fiber diameter is in the range of about 1 micrometer to about 15 micrometers. Most desirably, the average fiber diameter is in the range of about 1 micrometer to about 10 micrometers. The standard deviation of the average fiber diameter should exceed 0.5 micrometer.

The nonwoven web 12 has a basis weight of at least about 0.5 grams per square meter (gsm). Desirably, the nonwoven web 12 has a basis weight of at least about 1 gsm. More desirably, the nonwoven web 12 has a basis weight of at least about 20 gsm. Even more desirably, the nonwoven web 12 has a basis weight of at least about 50 gsm. Most desirably, nonwoven web 12 has a basis weight of greater than about 100 gsm.

The nonwoven web 12 has a force of about 10 grams per gram per square meter of the nonwoven web (gf/gsm/cm nonwoven web width) (9) as measured in the machine direction (MD) of the nonwoven web. , 810 newtons/[(kg/m ² )×m non-woven web width]) to about 100 gf/gsm/cm non-woven web width (98,100 newtons/[(kg/m ² )×m non-woven web width]] ) Has a tensile strength in the range up to. Desirably, nonwoven web 12 has a width of about 12 gf/gsm/cm nonwoven web (11,772 newtons/[(kg/m ² )×m nonwoven) as measured in the machine direction (MD) of the nonwoven web. Web width]) to about 80 gf/gsm/cm non-woven web width (78,480 Newtons/[(kg/m ² )×m non-woven web width]). More desirably, the nonwoven web 12 has a width of the nonwoven web of about 13 gf/gsm/cm (12,753 Newtons/[(kg/m ² )×m nonwoven) as measured in the machine direction (MD) of the nonwoven web. Woven web width]) to about 70 gf/gsm/cm non-woven web width. Even more desirably, the nonwoven web 12 has a nonwoven web width of about 14 gf/gsm/cm nonwoven web width (13,734 Newtons/[(kg/m ² )×m), as measured in the machine direction (MD) of the nonwoven web. Nonwoven web width]) to about 60 gf/gsm/cm nonwoven web width (58,860 newtons/[(kg/m ² )×m nonwoven web width]). Most desirably, the nonwoven web 12 has a nonwoven web width (14,715 newtons/[(kg/m ² )×m nonwoven) of about 15 gf/gsm/cm nonwoven web width, measured in the machine direction (MD) of the nonwoven web. Woven web width]) to about 50 gf/gsm/cm non-woven web width (49,050 newtons/[(kg/m ² )×m non-woven web width]).

The fibers 98 forming the nonwoven web 12 are randomly arranged.

The fibers 98 forming the nonwoven web 12 may be combined to increase the integrity of the nonwoven web 12. The fibers 98 can be bonded using various techniques. For example, the fibers 98 can be mechanically bonded, hydrodynamically bonded, thermally bonded, chemically bonded, or the like. Spot bonding, zone bonding as well as other bonding techniques known to those skilled in the art can be used.

The following experiments were conducted and the results of these experiments show the unique properties of nonwoven webs 12 produced using the apparatus 10 and method described above.

Experiment
1. Nonwoven web of the present invention Multi-row spinnerets 52,52 manufactured by Biax-FiberFilm Corporation with offices at N992 Quality Drive, Soot B, Greenville, Wisconsin 54942-8635. The following non-woven samples were made using a pilot line with two 25° dies fixed to each other. Each spinneret 52, 52, having a total of at 4,150 nozzles, each nozzle had an inside diameter d ₃ of 0.305 mm. Each nozzle 58 was surrounded by a first enlarged opening 80 in an outer member 78 through which pressurized gas (air) could flow. The inner diameter d ₆ of each of the first enlarged openings 80 was 1.4 mm. By way of comparison, a typical commercial spinneret manufactured by Biax-Fiber Film Corporation can have from about 6,000 to about 11,000 nozzles per meter. Conventional meltblown material 22 (polymer) was obtained from different suppliers, but the process conditions and system parameters are disclosed in Table 1.

Table 1

2. Process Conditions Several types of nonwoven webs were made using the pilot line described above.
Three different polymer resins were used. The first polymer resin was a polypropylene (PP) resin manufactured by ExxonMobil under the tradename Achieve 6936G1. ExxonMobil Chemical has offices in Katy Freeway 13501, Houston, Texas 77079-1398. Achieve 6936G1 has a melt flow rate of 1,550 grams/10 minutes (g/10 minutes) according to American Standard Test Method (ASTM) D1238 at 210° C. and 2.16 kg. The second polymer resin was ExxonMobil polypropylene-PP3155. PP3155 has a melt flow rate of 35 g/10 min according to American Standard Test Method (ASTM) D1238 at 210° C. and 2.16 kg. The third polymer resin was Metocene MF650W marketed by LyondellBasell. Lyon Del Basel has offices in Lyon Del Basel Tower, 1221 McKinney Street, Houston, Houston 77010, Texas. Metocene MF650W has a melt flow rate of 500 g/10 min according to American Standard Test Method (ASTM) D1238 at 210° C. and 2.16 kg. The process conditions for the different samples are disclosed in Table 1.

3. Characteristic determination method
3.1 Basis weight Basis weight is defined as the mass per unit area, which can be measured in units of grams per square meter (g/m ² ) or ounces per square yard (osy). Is. Basis weight tests were performed according to INDA standard IST 130.1, which is equivalent to ASTM standard ASTM D3776. INDA is an abbreviation for "Association of the Non-Woven Fabrics Industry". Ten different samples were die cut from different locations in the nonwoven, each sample having an individual area equal to 100 square centimeters (cm ² ). The weight of each sample was measured within ±0.1% of the weight on this balance using a high sensitivity balance. Basis weight was measured in grams/square meters (g/m ² ) by multiplying the average weight by 100.

3.2 Fiber Diameter Measurement To examine the morphological characteristics of the fibers and the fiber diameter distribution of the produced nonwoven web, the sample was sputter coated with a thin layer of 10 nanometers (nm) of gold and the Netherlands 9652AM. Analysis was performed with a scanning electron microscope model SEM, Phenom G2, manufactured by Phenom World BV, which has a sales office in Dillenberg-Strat 9E, Eindhoven. Images were taken at 500x and 1500x magnification under an accelerating voltage of 5 kilovolts (kV) for the electron beam. Fiber diameter was measured using Image J software. "Image J" is a Java (registered trademark) compliant image processing program, which is a public property developed by the National Institutes of Health, and can be downloaded from http://imagej.nih.gov/ij/ .. At least 100 individual fiber diameters were measured for each sample.

3.3 Fabric Tensile Strength Break Force is defined as the maximum force applied to a supported nonwoven web to break or break. For ductile materials such as non-woven webs, the non-woven web experiences maximum force before breaking. Tensile strength was measured according to ASTM standard D5035-90 which is identical to INDA standard IST 110.4 (95). To measure the tensile strength of the nonwoven web, six sample strips from each nonwoven web were cut at different locations across the width of the nonwoven web, each strip being 25.4 millimeters (mm). )×152.4 mm (1 inch×6 inch). Each strip was clamped between the jaws of a tensile tester, which was a Swing Albert Tensile Tester. The clamp pulled the strip at a constant extension rate of 10 inches (25.4 cm)/min. The average breaking force and the average percent elongation at breaking force were recorded for each nonwoven in units of grams force per width per basis weight of the nonwoven web (gf/gsm/cm).

3.4 Air Permeability Measurement The air permeability of a nonwoven fabric is the measured air flow rate through the area of the fabric at a particular pressure drop. The air permeability was measured on the fiber mats with a pressure drop equal to 125 Pa using an Akstron Air Permeability Tester. Ten measurements were recorded for each mat, and the average value is recorded here. This method of measuring air permeability is equivalent to the Frazier type air permeability test method or the ASTM D737 test method.

Example 1
In this example, the inventor has seen the effect of spinning techniques on web properties. Three different nonwoven webs were made using the same polymeric resin. All three had the same basis weight, but each nonwoven web was spun using different spinneret designs and different processing conditions. As shown in Table 2, a sample S-1 was made using a Biax multi-row spinneret design, but this bi-ax multi-row spinneret design uses the air insulation insert 34 or the first enlarged opening. There was no air enclosure curtain (second enlarged opening 82) surrounding the perimeter 84 of section 80. Sample S-2 was manufactured using the conventional meltblown method, which had nozzles that only lined up with a tilted air jet. Sample S-3 was prepared using the method of the present invention.

Sample S-3 achieved almost twice the tensile strength in the machine direction (MD) as compared to Sample S-1 or Sample S-2. Also, as noted, the fiber diameter of sample S-3 was slightly larger than the fiber diameter of conventional meltblown sample S-2. The main reason for this difference in diameter is that the cold air in the annular channel is directed essentially parallel to the flow direction of the filament 86 in a multi-row fashion using the method of the present invention. In addition, damping the fibers 98 with a cold gas (air) can increase the crystallinity of the fibers and align the molecular chains within the fibers 98 after solidification. This feature facilitates the damping of the filament into strong, thin fibers 98. In the conventional meltblown method, a hot air jet is used to introduce damping air at a steep or inclined angle.

Referring now to FIG. 12, another interesting feature of the nonwoven web 12 made in accordance with the present invention is the broad "fiber diameter distribution." Comparing this "fiber diameter distribution" with the "fiber diameter distribution" of the nonwoven web produced using the conventional melt blown method, it is very clear that the standard deviation value and the "fiber diameter distribution" are very different. Is. The main reason for this broad "fiber diameter distribution" within our device 10 is the use of a multi-row spinneret design. The filaments 86 (see FIG. 10) exiting the nozzle 58 arranged with the perimeter 84 are not exposed to the surrounding ambient air and rapid quenching time, and thus these filaments 86 are long. It tends to remain hot, resulting in finer fibers 98 than filaments 86 being extruded from nozzles 58 located in the outer row of spinneret bodies 52. By replacing the nozzle 58 with a stationary pin 62 in an outer row 64 located adjacent the perimeter 68 (see FIG. 7), an air curtain or shroud is wrapped around the extruded filaments 86. It is formed. This air curtain or shroud slows the interaction of the extruded filament 86 with the surrounding ambient air. This delay prevents solidification at the distal tip 96 of each nozzle 58 and reduces the shot and rope defects found with the older biax multi-row spinneret. This early multi-row spinneret was taught in US Pat. No. 5,476,616. The expression "shot defects" means small spherical particles of polymer that form during the web forming process. Table 2 also shows that the airways of the spanblown sample S-3 are at least 50% higher than the conventional meltblown sample S-1 made under the same conditions. The main reason for this increase is that the fiber diameter is large and the fiber diameter distribution reflected in the standard deviation of the fiber size is wide.

注：１ｇｆ／ｇｓｍ／ｃｍ＝９８１ニュートン／（ｋｇ／ｍ²）×メートル Table 2: Sample performance of Example 1

Note: 1 gf/gsm/cm=981 Newton/(kg/m ² )×meter

It should be understood that the fibers 98 in the nonwoven web 12 may have a standard deviation of about 0.9 micrometers to about 5 micrometers. Desirably, the fibers 98 in the nonwoven web 12 have a standard deviation of about 0.92 micrometers to about 3 micrometers. More desirably, the fibers 98 in the nonwoven web 12 have a standard deviation of about 0.95 micrometers to about 1.5 micrometers.

Example 2
This second example compares sample S-5 made by the method of the present invention with sample S-4 made by the conventional meltblown method and sample S-6 made by the conventional spunbond method. .. Three samples were made, but each sample had the same basis weight. As shown in Table 3, the properties of Sample S-5 were approximately in the middle of those of Meltblown Web S-4 and Spambond S-6. Table 3 also shows that the air permeability of sample S-5 (made using the method of the invention) is approximately in the middle of conventional meltblown sample S-4 and conventional spunbond sample S-6. Showing. This shows that the inventors' new technique is capable of producing a nonwoven web which has a fine fiber diameter about the same as meltblown fibers, but is stronger than spunbond fibers.

Referring to FIG. 13, the nonwoven web 12 (Sample S-5) of the present invention has a machine direction (MD) tensile strength that is greater than twice the MD tensile strength of the meltblown web sample S-4 and is spunbonded. It was almost half the MD tensile strength of web sample S-6. Another notable feature is that the nonwoven web 12 of the present invention (Sample S-5) has an elongation that is approximately three times that of the meltblown web sample S-4 and that of the spunbond web sample S-6. It was almost the same as the growth rate.

From the above two samples, the non-woven web 12 made using the apparatus and method of the present invention is unique, yet non-woven web made using the conventional meltblown process or a conventional spunbond process. It has properties that are approximately in the middle of those exhibited by the nonwoven webs made with it.

Further, the apparatus 10 of the present invention is sufficiently flexible and versatile to use a wide variety of polymeric resins to make a wide variety of nonwoven webs. Meltblown grade resins as well as spunbond grade resins can be used to operate the apparatus 10.
Table 3: Sample performance of Example 2

Although the present invention has been described in connection with some specific embodiments, it should be understood that many variations, modifications, and variations to those skilled in the art in light of the above description. Is clear.

Claims (20)

A non-woven web composed of a plurality of fibers made of a molten polymer, the fibers having an average fiber diameter in the range of about 0.5 microns to about 50 microns and a basis weight of at least about. A nonwoven web having a tensile strength, measured in the machine direction, of 0.5 gsm and ranging from about 12 gf/gsm/cm nonwoven web width to about 100 gf/gsm/cm nonwoven web width. The nonwoven web of claim 1, wherein the average fiber diameter is in the range of about 1 micron to about 30 microns. The nonwoven web of claim 1, wherein the average fiber diameter is in the range of about 1 micron to about 20 microns. The nonwoven web of claim 1, wherein the average fiber diameter is in the range of about 1 micron to about 10 microns. The nonwoven web of claim 1, wherein the molten polymer is a homopolymer. The non-woven web of claim 1, wherein the non-woven web is made from two different polymeric resins. The nonwoven web of claim 1, wherein the plurality of fibers in the nonwoven web have a standard deviation in the range of about 0.9 microns to about 5 microns. The non-woven web of claim 1, wherein the fibers are randomly arranged. 9. The nonwoven web of claim 8, wherein the fibers are mechanically bonded. A non-woven web composed of a plurality of fibers made of a molten homopolymer, said fibers having an average fiber diameter in the range of about 0.5 microns to about 50 microns and a basis weight of at least A nonwoven web having a tensile strength measured in the machine direction of about 0.5 gsm in the range of about 12 gf/gsm/cm nonwoven web width to about 80 gf/gsm/cm nonwoven web width. The non-woven web of claim 10, wherein the fibers are hydrodynamically bonded. 11. The nonwoven web of claim 10, wherein the fibers are thermally bonded. The nonwoven web of claim 10, wherein the fibers are chemically bonded. The average fiber diameter is in the range of about 1 micron to about 10 microns, and the tensile strength is in the range of about 13 gf/gsm/cm nonwoven web width to about 70 gf/gsm/cm non-woven web width. 13. The nonwoven web of claim 10, wherein 11. The nonwoven web of claim 10, wherein the homopolymer is polypropylene. A non-woven web composed of a plurality of fibers made of molten homopolymer, the fibers having an average fiber diameter in the range of about 1 micron to about 50 microns and a basis weight of at least about 1 gsm. And a tensile strength measured in the machine direction in the range of about 15 gf/gsm/cm nonwoven web width to about 50 gf/gsm/cm nonwoven web width. The nonwoven web of claim 16, wherein the average fiber diameter is in the range of about 1 micron to about 30 microns. 17. The nonwoven web of claim 16, wherein the average fiber diameter is in the range of about 1 micron to about 15 microns. The nonwoven web of claim 16, wherein the average fiber diameter is in the range of about 1 micron to about 10 microns. 18. The nonwoven web of claim 16, wherein the fibers are randomly arranged and mechanically bonded.

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