Patent Application
20220298691
This application relates to non-woven fabrics and, more particularly, to non-woven fabrics intended for use in applications, such as surgical, hygiene, and infection-prevention products, where good physical and mechanical properties are required.
Fibrous materials are used in a number of products related to surgical procedures, hygiene, and infection prevention. They may be used to form surgical gowns, drapes, sterilization solutions, gloves, facemasks, protective apparel, disposable diapers, hygiene products, etc. In some cases, it may be desirable for the fibrous material to be lightweight, thin, and easy to use. While use of hollow fibers in such materials has been proposed, existing non-woven materials based on hollow fibers have limited mechanical and/or physical properties that make them unsuitable in the above-mentioned applications. For example, existing non-woven materials formed using hollow fibers can soften and weaken under sterilization temperatures. Such weakening of the fabric makes them more susceptible to cuts, holes, and potential tears propagated during use, and thus makes the fibers unsuitable for inclusion in fabrics and other materials for use in many surgical, hygiene, and infection prevention applications.
The terms “invention,” “the invention,” “this invention” and “the present invention” used in this disclosure are intended to refer broadly to all of the subject matter of the disclosure and the claims below. Statements containing these terms should be understood not to limit the subject matter described herein or the meaning or scope of the claims below. Covered embodiments of the invention are defined by the claims below, not this summary. This summary is a high-level overview of various embodiments of the invention and introduces some of the concepts that are further described in the Detailed Description section below. This summary is not intended to identify key or essential features of the claimed subject matter, nor is it intended to be used in isolation to determine the scope of the claimed subject matter. The subject matter should be understood by reference to appropriate portions of the entire specification, any or all drawings, and each claim.
According to certain embodiments of the present disclosure, a fiber includes a fiber body having a length. The fiber body is formed from a blend of a first polymer and at least 10% by weight of a second polymer, a melt flow rate (MFR) of the first polymer being greater than a MFR of the second polymer. In various examples, a plurality of the fibers may be formed as a spunbond layer on a REICOFIL® III line, on a REICOFIL® IV line, or on a REICOFIL® V line.
In some examples, the fiber may be a hollow fiber or a solid fiber. Optionally, when the fiber is a hollow fiber, the fiber body defines a hollow cavity. In some cases, the hollow cavity constitutes up to about 25% of the volume of the fiber body.
In certain examples, a fabric formed with the hollow or solid fiber has an improved mechanical property in at least one of a machine direction or a cross-machine direction compared to a fabric with a fiber comprising only the first polymer. In various cases, the improved mechanical property includes at least one of a trap tear strength, a strip tensile strength, a puncture resistance, and a grab tensile strength. In certain aspects, the at least one direction is the machine direction. In various examples, a spunbond non-woven fabric includes the hollow fiber or solid fiber. A weight of the spunbond may be less than 105 gsm.
According to certain embodiments of the present disclosure, a spunbond non-woven fabric includes a plurality of fibers, and the fibers are formed from a polymer blend having at least one first polymer and at least one second polymer. A MFR of the at least one first polymer is greater than a MFR of the at least one second polymer, the MFR of the at least one second polymer is less than 18 g/10 min, and the blend comprises a percentage by weight of the second polymer that is greater than a percentage by weight of the first polymer
According to certain embodiments of the present disclosure, a spunbond non-woven fabric includes a plurality of fibers, and the fibers are formed from a polymer blend including at least one first polymer and at least one second polymer. A MFR of the at least one first polymer is from about 19 g/10 min to about 40 g/10 min, and a MFR of the at least one second polymer is about 9 g/10 min to about 18 g/10 min. The blend may include at least 10% by weight of the at least one second polymer, and an average diameter of each fiber is from about 13 microns to about 22 microns.
According to certain embodiments of the present disclosure, a spunbond non-woven fabric includes a plurality of hollow fibers, and the hollow fibers are formed from a polymer blend having at least one first polymer and at least one second polymer. A MFR of the at least one first polymer is greater than a MFR of the at least one second polymer, the MFR of the at least one second polymer is about 9 g/10 min to less than 18 g/10 min, and the blend includes at least 10% by weight of the second polymer. The hollow fibers each include a fiber body that defines a cavity within the fiber body, the cavity and the fiber body together define a total volume, and the fibers include a hollowness of at least 5% by volume of the total volume.
Various implementations described in the present disclosure can include additional systems, methods, features, and advantages, which cannot necessarily be expressly disclosed herein but will be apparent to one of ordinary skill in the art upon examination of the following detailed description and accompanying drawings. It is intended that all such systems, methods, features, and advantages be included within the present disclosure and protected by the accompanying claims.
The features and components of the following figures are illustrated to emphasize the general principles of the present disclosure. Corresponding features and components throughout the figures can be designated by matching reference characters for the sake of consistency and clarity.
The subject matter of embodiments of the present invention is described here with specificity to meet statutory requirements, but this description is not necessarily intended to limit the scope of the claims. The claimed subject matter may be embodied in other ways, may include different elements or steps, and may be used in conjunction with other existing or future technologies. This description should not be interpreted as implying any particular order or arrangement among or between various steps or elements except when the order of individual steps or arrangement of elements is explicitly described.
As used herein, mass flow rate (MFR) is measured according to ASTM D1238-13, entitled STANDARD TEST METHOD FOR MELT FLOW RATES OF THERMOPLASTICS BY EXTRUSION PLASTOMER and published in 2013 (“ASTM D1238”) (incorporated herein by reference). MFR is expressed (SI units) in g/10 min, and is the mass of polymer, in grams, flowing in ten minutes through a capillary of a specific diameter (typically about 2 mm) and length by a pressure applied via a range of standard weights at a specified temperature (e.g., 190° C. for polyethylene and 230° C. for polypropylene). As used herein, a “high MFR” polymer is a polymer having a MFR of greater than 18 g/10 min, and a “low MFR” polymer is a polymer having a MFR of from about 9 g/10 min to less than 18 g/10 min. High MFR polymers have lower viscosities and have lower strength, while low MFR polymers have higher viscosities and are typically much stronger than high MFR polymers.
Fibers
Disclosed are fibers useful in non-woven fabrics to give the fabrics mechanical and/or physical properties that are improved over properties of known non-woven materials, making the fibers/nonwovens useful for a number of different applications. In some examples, the fibers include blends of low MFR polymers and high MFR polymers, and the blend includes at least 10% by weight of the low MFR polymers. In various examples, the fibers may also have an average diameter of less than about 30 microns. In certain examples, the fibers may be hollow.
As illustrated in
The fiber body 102 may be formed from a blend of polymers. In particular, the fiber body 102 may be formed from a blend of at least one high MFR polymer and at least one low MFR polymer. Examples of high MFR polymers include polypropylenes polymerized using a Ziegler-Natta catalyst (Ziegler-Natta polypropylene). Examples of low MFR polymers include polypropylenes polymerized using a metallocene catalyst (metallocene polypropylene). Traditionally, melt-spun fibers have been formed only from high MFR polymers because their lower viscosities render them easier to spin into filaments. Conversely, low MFR polymers have not been used in melt-spinning fibers, particularly hollow fibers, because their higher viscosities make it more difficult to spin the material into filaments. While high MFR polymers are more easily spun, the resulting solid fiber and/or hollow fiber often has mechanical and/or physical properties that are weakened by high temperatures and/or other extreme conditions and/or due to the lower average molecular weight of the higher MFR polymer. For example, hollow fibers made from high MFR polymers could soften and weaken during steam sterilization, rendering the fabrics into which they are incorporated more susceptible to cuts, holes, and tears during use and thus making them unsuitable for many surgical, hygiene, and infection prevention applications. Moreover, hollow fibers are prone to collapse as the material is not strong enough to retain the hollow structure of the fiber.
It has been discovered that a blend of at least one high MFR polymer and at least one low MFR polymer, where the blend includes at least 10% by weight of the at least one low MFR polymer may be formed into hollow filaments or fibers and spun into fabrics or other products having improved mechanical and/or physical properties (e.g., stable during steam sterilization, puncture resistance, strength, etc.) compared to fabrics having fibers that are not blended. In various aspects, the low MFR polymers may have a MFR of from about 9 g/10 min to about 18 g/10 min. In one aspect, the blend (and thus the resulting fibers) includes from about 10% to about 90% by weight low MFR polymers, such as about 10% by weight low MFR polymers, about 20% by weight low MFR polymers, about 30% by weight low MFR polymers, about 40% by weight low MFR polymers, about 50% by weight low MFR polymers, about 60% by weight low MFR polymers, about 70% by weight low MFR polymers, about 80% by weight low MFR polymers, and/or about 90% by weight low MFR polymers. Various other percentages of the low MFR polymers between 10% and about 90% may also be utilized.
In some examples, the polymer blend (and thus the resulting fibers) may include from about 10% to about 90% by weight high MFR polymers, such as about 20% by weight high MFR polymers, about 30% by weight high MFR polymers, about 40% by weight high MFR polymers, about 50% by weight high MFR polymers, about 60% by weight high MFR polymers, about 70% by weight high MFR polymers, about 80% by weight high MFR polymers, and/or about 90% by weight high MFR polymers. Various other percentages of the high MFR polymers between 10% and less than about 100% may also be utilized.
In addition to the low MFR polymers and the high MFR polymers, the polymer blend may also include other components or additives. In such examples where additional components are added, the blend may include from about 0% to about 10% by weight of the additional components. In various aspects, the additional components may include plastomers, elastomers, pigments, fluorochemicals, antimicrobials, surfactants, anti-stats, and/or various other additives or combinations of additives or other components. In one non-limiting example, the additive may include titanium dioxide. Again, however, in some embodiments the polymer blend is formed exclusively of low and high MFR polymers.
In some embodiments, the low MFR polymers have a MFR of from about 9 g/10 min to less than 18 g/10 min. For example, in some cases, the low MFR polymers have a MFR of about 9 g/10 min, about 10 g/10 min, about 11 g/10 min, about 12 g/10 min, about 13 g/10 min, about 14 g/10 min, about 15 g/10 min, about 16 g/10 min, about 17 g/10 min, and/or various combinations thereof. For example, the blend may include a single type of low MFR polymer or two or more low MFR polymers that have a different MFR, although it need not in other examples.
The high MFR polymers may have a MFR of greater than 18 g/10 min as described previously, and in various cases, may be from about 25 g/10 min to about 40 g/10 min. For example, in some cases, the high MFR polymers may have a MFR of about 19 g/10 min, about 20 g/10 min, about 21 g/10 min, about 22 g/10 min, about 23 g/10 min, about 24 g/10 min, about 25 g/10 min, about 26 g/10 min, about 27 g/10 min, about 28 g/10 min, about 29 g/10 min, about 30 g/10 min, about 31 g/10 min, about 32 g/10 min, about 33 g/10 min, about 34 g/10 min, about 35 g/10 min, about 36 g/10 min, about 37 g/10 min, about 38 g/10 min, about 39 g/10 min, and/or about 40 g/10 min, various combinations thereof, or various other suitable high MFR polymers. In some examples, the high MFR polymers have a MFR of about 35 g/10 min. Similar to the low MFR polymers, the blend may include a single type of high MFR polymer or two or more high MFR polymers that have a different MFR, although it need not in other examples.
In some examples, the polymer blend may include combinations of multiple low MFR polymers and/or multiple high MFR polymers. For example, in some cases, the blend may include two or more low MFR polymers (e.g., one low MFR polymer having a MFR of 9 g/10 min and the other low MFR polymer having a MFR of 11 g/10 min) and one high MFR polymer (e.g., the high MFR polymer has a MFR of 35 g/10 min). In other embodiments, the blend may include one low MFR polymer and two or more high MFR polymers. In further embodiments, the blend may include one low MFR polymer and one high MFR polymer. In still other embodiments, two or more low MFR polymers and two or more high MFR polymers may be used. Various other combinations may be utilized.
In various examples, the polymers used as the low MFR polymers and/or the high MFR polymers include a polyolefin such as, but not limited to, polypropylene (PP) or polyethylene (PE). In some examples, the low MFR polymers and high MFR polymers may both be PP or PE, although they need not be in other examples. For example, in other cases, the polymers may be poly(lactic acid), poly(butylene succinate), metallocene polymers, ziegler-natta polymers, polyester, nylon, and/or various other polymers or combinations of polymers. In one example, the low MFR polymer is a metallocene propylene and the high MFR polymer is a ziegler-natta polypropylene. In some aspects, mixing polymers of two or more MFRS may help increase the percent hollowness of the resulting fiber by stabilizing the solid part of the hollow fiber and preventing or reducing the likelihood of it collapsing.
The hollow fibers described herein and formed with the blend of the low MFR polymers and high MFR polymers have a fiber body that surrounds and defines a cavity. The fiber body and the cavity together define a total volume, and the fiber has a hollowness that is defined herein as the percentage of the total volume occupied by the cavity. In some examples, the hollow fibers may have a hollowness of up to about 40% (i.e., 40% of the volume of the fiber is hollow). In some examples, fibers formed with the blend of the low MFR polymers and high MFR polymers may have a hollowness of from about 5% to about 40%, such as a hollowness of from about 10% to about 30%, such as a hollowness of from about 10% to about 20%, such as a hollowness of from about 7% to about 15%, such as a hollowness of from about 7% to 10%. In certain examples, the hollow fibers may have a hollowness of from about 20% to about 25%.
In various examples, the fibers may be formed to have various suitable external diameters. In some examples, the fibers have an external diameter of less than about 30 microns. For example, in some cases, the fibers have an external diameter of from about 11 microns to about 27 microns, such as about 11 microns, about 12 microns, about 13 microns, about 14 microns, about 15 microns, about 16 microns, about 17 microns, about 18 microns, about 19 microns, about 20 microns, about 21 microns, about 22 microns, about 23 microns, about 24 microns, about 25 microns, about 26 microns, and/or about 27 microns. In other examples, the fibers may have an external diameter that is less than 15 microns and/or greater than 30 microns. The smaller the diameter of the fibers, the finer the fibers, and as such, smaller diameter or finer fibers may have an increased number of contact points with other fibers in a product compared to larger diameter fibers, and the increased contact may increase the strength of the product. The smaller diameter fibers may also provide increased coverage compared to larger fibers. As discussed in detail below, in various aspects, the weight of the fibers and the diameter of the fibers may be controlled to control mechanical and/or physical properties of products that utilize the fibers.
Fibers according to the present disclosure provide a number of advantages over traditional fibers. Embodiments of the fibers formed from a blend of at least one low MFR polymer and at least one high MFR polymer enjoy the benefits that each of the polymer types brings to the blend, while the drawbacks of each polymer is counteracted or neutralized by the other polymer in the blend. Thus, fibers may be customized or tailored to produce desired results (e.g., material savings, increased strength, ease of manufacture, etc.).
For example, inclusion of low MFR polymers in the blend strengthens the fiber, rendering it less apt to collapse or break. In some cases, having at least 10% by weight of the low MFR polymers strengthens the fibers. In various examples, the percentage of low MFR polymers is greater than the percentage of high MFR polymers.
This increase in structural integrity allows one to optionally make the fibers hollow (and enjoy the consequent material cost savings) without detrimentally affecting the fiber's strength and other mechanical and/or physical properties. The low MFR polymer is also better able to withstand the sterilization process without degradation. Thus, a fiber of the present disclosure may be formed to have the same or better mechanical and/or physical properties as traditional fibers while using use less material (because they are hollow). Consequently, products into which they are incorporated may be more lightweight, may be thinner, and may be stronger.
Alternatively, a fiber formed in accordance with embodiments disclosed herein could also use more material (i.e., the fiber is solid or has a reduced percentage hollowness) to further improve its strength and other properties of the fiber. In such cases, fibers according to the present disclosure may have improved mechanical and/or physical properties (degradation resistance, strength, etc.) by virtue of the presence of low MFR polymers while having the same solidness and/or hollowness as traditional fibers. Various other advantages may be provided with hollow fibers of the current disclosure, and the above listing should not be considered limiting.
Furthermore, inclusion of the high MFR polymer in the blend allows the blend—which includes low MFR polymers that are difficult to spin—to be spun into filaments more easily. Moreover, the blend forming the fiber may facilitate quenching and drawing of the fibers and enhance the effects of those procedures (and thus the mechanical and/or physical properties of the fibers) compared to traditional fibers. Without wishing to be bound by theory, quenching and drawing may be facilitated by both the exterior and the interior (through the hollow core) of the hollow fibers are exposed to treatment during the process. Improved quenching and drawing may result in increased strength of the fibers and resistance to degradation, collapsing, defects, etc. compared to traditional hollow fibers. In various aspects, the low MFR polymer may also help the fiber maintain more hollowness without collapsing on itself because the low MFR polymer has a higher melt strength (and as such, a greater percentage of the fiber has the higher melt strength), which may prevent the collapse of the hollowness during the drawing down. Various other advantages may be realized with hollow fibers according to embodiments of the present disclosure, and those identified above should not be considered limiting.
In various examples, one or more parameters of the fibers may be controlled to produce products having improved mechanical and/or physical properties. As one example, the blend of polymers is controlled to provide stronger hollow or solid fibers. In one non-limiting example, a strong blend of polymers includes 30% high MFR polymers and 70% low MFR polymers. In another non-limiting example, a strong blend of polymers includes 20% high MFR polymers and 80% low MFR polymers. Various other blends of low MFR polymers and high MFR polymers may be utilized. As another example, the average diameter of the fibers is controlled (optionally in conjunction with a strong blend of polymers) to provide improved mechanical and/or physical properties. In one non-limiting example, the average diameter of the fibers is controlled to be about 15 microns to about 20 microns, although various other average diameters may be utilized. As an additional example, the percent hollowness of the fibers is controlled. In some cases, the fibers may be solid, while in other examples, the fibers may up to 40% hollow.
Fabrics
Also disclosed herein are fabrics formed from the fibers described herein. The fibers described herein may be used to form a variety of different fabrics, including, but not limited to, spunbond non-woven materials or fabrics. In general, a spunbond (also called spunlaid) non-woven includes a web of stretched fibers of a thermoplastic resin. Generally, the spunbond is produced by depositing extruded, spun fibers as a web onto a collecting belt (usually in a random manner) followed by bonding the fibers. In some examples, the fibers may form a spunbond fabric that is a single layer; however, in other examples, the fibers may form a fabric that includes a plurality of spunbond layers. Further, the single or plurality of spunbond layers maybe combined with another type of layer such as a meltblown layer.
In certain aspects, spunbond fabrics described herein may be incorporated into products including, but not limited to surgical gowns, sterilization wraps, respirators, absorbent pads, wound care products, chemical protection apparel, filtration media, hospital towels, hospital apparel, drapes, gloves, facemasks, sanitary napkins, diapers, SMS wraps, surgical products (SMS, spunbond, etc.), hygiene products (SMS, spunbond, etc.), and other types of protective and/or hygienic products. In other aspects, the fibers disclosed herein may be used to form various other suitable non-woven products. It will be appreciated that different polymer blends may be used to form the fibers depending on the desired end-use application (e.g., a personal care application could include one blend, a health care application could include another blend, an industrial application could use a further blend, etc.). In still other embodiments, the fibers may be provided in filament form or in staple form that is spun into yarns. These yarns may subsequently be used to form any type of fabric or substrate, including, but not limited to, knitted, woven, and non-woven fabrics and substrates. In some cases, the fibers could be used in carded thermally bonded non-wovens, hydroentangled non-woven materials (e.g., where cellulose or other fibers are combined with layers of the fibers), bicomponent materials (e.g., where bicomponent materials can be used with the fibers), and/or various other applications.
In some examples, fabrics formed with the blended fibers may have a high weight or a low weight. As used herein, a “high weight” refers to less than about 105 gsm, such as from greater than about 30 gsm to about 105 gsm, and low weight such as from about 6 gsm to about 30 gsm. In various examples, the weight of the fabric used may be controlled depending on the desired product that incorporates the fibers. As some non-limiting examples, the fabric may be a spunbond (S)—meltblown (M)—spunbond (S) wrap (i.e., a SMS wrap) (which includes a meltblown layer between spunbond layers), and may have a weight of from about 25 gsm to about 105 gsm. In other examples, the fabric may be a surgical gown having a weight of from about 17 gsm to about 105 gsm, and/or a hygiene product having a weight of from about 6 gsm to about 15 gsm. It will be appreciated that the above ranges should not be considered limiting on the particular products and are provided only as examples. While a SMS fabric is described, it will be appreciated that other patterns of layers of spunbond and meltblown (or other layers) may be utilized. For example, a fabric may have SM layers, SMMS layers, S layers, SS, layers, SMMMS layers, SSMMS layers, etc. as desired.
In some examples, the fibers described herein form a spunbond non-woven fabric. The spunbond non-woven fabric may have a calendar bond pattern with a bond area of from about 12% to about 35%, such as about 30%, although various other bond areas may be utilized. The percent bond area on the fabric is determined by the bond pattern of the calendar roll, and the fabric strength correlates with bond area. In one non-limiting example, the bond area of the calendar bond pattern is about 30%. The bond area of the calendar bond pattern may be controlled (optionally in conjunction with the fiber average diameter, hollowness, and/or blend) to provide improved mechanical and/or physical properties.
Method of Production
After passing through the spinneret 306, the fibers may be quenched with air from an air generator 308. The fibers may then be melt drawn using a fiber draw device 310. The fibers may be drawn to form the fiber with a desired length. After drawing, the fibers may be deposited for further processing as desired, such as crimping, texturizing, cutting, incorporation into a non-woven web, etc.
In other examples, the hollow (or solid) fibers described herein and/or products incorporating the fibers described herein may be produced in accordance with the REICOFIL® III method and system sold by Reifenhauser Gmbh & Co. Maschinenfabrik. The REICOFIL® III system and method is extensively described in U.S. Pat. No. 5,814,349 (“the '349 patent”). The '349 patent is hereby incorporated by reference in its entirety. As described in the '349 patent, the REICOFIL® III method and system can include: a spinneret that produces strands; cooling means below the spinneret for cooling the strands from the spinneret to form filaments; a stretching system that receives the thermoplastic filaments for aerodynamic stretching; a web-depositing system below the stretching system in which a web of the tangled and stretched filaments are deposited; a continuously circulating sieve belt for forming a web from the tangled filaments; means for forming an air inlet gap; a first pair of pressing rollers; a second pair of pressing rollers; means forming a suction shaft for drawing the filaments against the belt; and/or means for functionally separating the stretching system from the web depositing system. In some cases, the REICOFIL® III system is a one-beam line with production speeds of up to 300 meters per minute, although it need not be in other examples. In other cases, the system may be a single beam line, a double beam line, a multiple beam line, etc. as desired. In some cases, the number of beam lines may depend on the desired number of layers in the final product. The spinneret may be a two segment spinneret (meaning that the spinneret forms a hollow cavity in each fiber having two sides), a three segment spinneret (meaning that the spinneret forms a hollow cavity in each fiber having three sides), a four segment spinneret (meaning that the spinneret forms a hollow cavity in each fiber having four sides), spinnerets having various other suitable designs, or various other suitable spinnerets. In certain examples, the smaller segment spinnerets (e.g., two segment spinnerets) may form fibers having smaller openings (i.e., reduced hollowness) compared to those formed by greater segment spinnerets (e.g., four segment spinnerets).
In various other examples, the hollow (or solid) fibers described herein and/or products incorporating the fibers described herein may be produced in accordance with the REICOFIL® IV method and system sold by Reifenhauser Gmbh & Co. Maschinenfabrik. The REICOFIL® IV system and method are extensively described in U.S. Pat. No. 6,918,750 (“the '750 patent”). The '750 patent is hereby incorporated by reference in its entirety. As described in the '750 patent, the REICOFIL® IV method and system can include: a spinneret that produces strands; cooling means below the spinneret for cooling the strands from the spinneret to form filaments; an intermediate channel; a stretching system that receives the thermoplastic filaments for aerodynamic stretching; a tiering or distribution unit; a continuously circulating belt or screen for forming a web from the tangled filaments; at least one first pair of pressing rollers; means forming a suction shaft for drawing the filaments against the belt; and/or means for functionally separating the stretching system from the tiering or distribution unit. In some cases, the REICOFIL® IV system is a one-beam line with production speeds of up to 600 m/min, although it need not be in other examples. In other cases, the system may be a single beam line, a double beam line, a multiple beam line, etc. as desired. In some cases, the number of beam lines may depend on the desired number of layers in the final product. The spinneret may be a two segment spinneret, a four segment spinneret, or various other suitable spinnerets.
In other examples, the fibers described herein and/or products incorporating the fibers described herein may be produced in accordance with the REICOFIL® V method and system sold by Reifenhauser Gmbh & Co. Maschinenfabrik. A difference between the REICOFIL® V system and other REICOFIL® systems is that the REICOFIL® V system has a higher throughput (e.g., 150-270 kg per hour and meter width compared to 120-200 kg per hour and meter width for REICOFIL® IV), a higher production speed (up to 1200 m/min), and improved uptime.
The mechanical properties of spunbond fabrics having solid fibers or hollow fibers consistent with embodiments described herein were tested according to accepted industry standard methods. Each sample fabric included fibers with a different blend of a high MFR PP polymer and a low MFR PP polymer. In each case, the spunbond fabrics were formed with a four segment spinneret unless described otherwise. The properties of the fabrics were measured at room temperature unless described otherwise. As used herein, the meaning of “room temperature” can include a temperature of from about 15° C. to about 30° C., for example about 15° C., about 16° C., about 17° C., about 18° C., about 19° C., about 20° C., about 21° C., about 22° C., about 23° C., about 24° C., about 25° C., about 26° C., about 27° C., about 28° C., about 29° C., or about 30° C. Unless otherwise specified, the term diameter refers to the fiber diameter measured in microns. For each example discussed below, the spunbond fabrics for the particular example were all spun with the same settings and parameters.
Sample spunbond fabrics were formed by a spunbonding process and using a four segment spinneret. The spunbond fabrics had fibers with different blends of Polymer 1 and Polymer 2. Polymer 1 was a polypropylene homopolymer having a MFR of 35 g/10 min. and a density of about 0.900 g/cm3, available from Exxon Mobil® as PP3155. Polymer 2 was a polypropylene homopolymer having a MFR of 14 g/10 min. and a density of about 0.905 g/cm3, available from Total® as M3661. The sample fabrics were tested according to the standards described below.
In this example, each sample fabric was a single spunbond layer of the fibers. The samples had the compositions shown in Table 1 below.
Tests 1-4 were each repeated twenty-four (24) times for each Sample to measure its mechanical properties. Tests 1-7 and 14 were performed according to ASTM D3822-14, entitled STANDARD TEST METHOD FOR TENSILE PROPERTIES OF SINGLE TEXTILE FIBERS and published in 2014 (incorporated herein by reference) (“ASTM D3822-14”), in dry conditions and in a direction of the length of the fabric. Tests 8-11 and 13 were performed using a video microscope and micrometer. Test 12 was performed according to STM-00161, Revision 0 from Kimberly-Clark, which is entitled DENIER MEASUREMENT USING A VIDEO MICROSCOPE AND MICROMETER and published Jun. 13, 2012 (incorporated herein by reference) (“STM-00161”).
The percent increase in tenacity (or strength) of spunbond fabrics having blended fibers with various percentages of Polymer 2 and Polymer 1 was tested according to ASTM D3822-14.
Sample fabrics were formed by a spunbonding process and using a four segment spinneret. The spunbond layers had different weights and fibers with different percentages of Polymer 1 and Polymer 2, and were tested according to the standards described below. Each sample fabric was a spunbond layer of fibers. The average diameter of the fibers of each sample fabric was 21 microns.
In this example, each sample was a single spunbond layer of the fibers. The samples had the compositions shown in Table 2 below.
Trapezoidal Tear Strength: Samples 9-14 described above were tested according to Standard Test Method STM-00195, Revision 0 from Kimberly-Clark, which is entitled TEARING STRENGTH—TRAPEZOID TEAR and published Jul. 19, 2012 (incorporated herein by reference (“STM-00195”), a measured in both the cross-machine direction (CD) and the machine direction (MD).
Strip Tensile Strength: Samples 9-14 described above were tested according to STM-00198, Revision 1 from Kimberly-Clark, which is entitled STRIP TENSILE OF NON-WOVEN MATERIAL and published Aug. 2, 2012 (incorporated herein by reference) (“STM-00198”), and were measured in both the machine direction and the cross-machine direction.
Puncture Resistance: Samples 9-14 described above were tested according to STM-00483, Revision 0 from Kimberly-Clark, which is entitled PUNCTURE RESISTANCE and published Dec. 17, 2015 (incorporated herein by reference) (“STM-00483”), and were measured in both the machine direction and the cross-machine direction.
Grab Tensile Strength: Samples 9-14 described above were tested according to STM-00146, Revision 1 from Kimberly-Clark, which is entitled GRAB TENSILE, PEAK STRETCH, AND PEAK ENERGY—NON-WOVENS and published Nov. 30, 2015 (incorporated herein by reference) (“STM-00146”), and were tested in both the machine direction and the cross-machine direction.
The results from these tests are summarized in
Sample fabrics were formed by a spunbonding process and using a four segment spinneret. The spunbond layers had different weights, were made from hollow fibers having different percentages of Polymer 1 and Polymer 2, and were tested for puncture resistance (according to STM-00483), grab tensile strength (according to STM-00146), trapezoidal tear strength (according to STM-00195).
The compositions of sample fabrics represented by the diagonally stripped pattern bars and the solid pattern bars are shown in Table 3 below.
As illustrated, fabrics with blended fibers formed from low MFR PP polymers and high MFR PP polymers had improved mechanical properties compared to the fabrics with fibers that were just high MFR PP polymers even though the fabrics with blended polymers had a reduced weight and the fibers of such fabrics had increased hollowness.
Sample fabrics were formed with different weights and from fibers having different average diameters and different percentages of Polymer 1 and Polymer 2 were tested for puncture resistance (according to STM-00483), grab tensile strength (according to STM-00146), and bursting strength (according to ISO 13932-2:1999, which is entitled TEXTILES—BURSTING PROPERTIES OF FABRICS—PART 2: PNEUMATIC METHOD FOR DETERMINATION OF BURSTING STRENGTH AND BURSTING DISTENSION and published in 1999 (incorporated herein by reference)).
Each fabric was produced as a SMS fabric having two spunbond layers and a meltblown layer laminated (calendered) between the spunbond layers. The weight of the meltblown layer was 17 gsm. In this example, the spunbond layer of each sample fabric was formed with a two segment spinneret. The meltblown layer included 100% meltblown grade polypropylene having a MFR of from about 155 MFR to about 800 MFR.
The composition of the samples in this example are shown below in Table 4.
Referring to the downward diagonal pattern bars of
Referring to the solid pattern bars of
Referring to the upward diagonal pattern bars of
Referring to the bars with the horizontal line pattern, the fabric with solid fibers with blend and the reduced average diameter (18 microns) generally had increased mechanical properties compared to the fabric with solid fibers with 100% high MFR polymers and the increased average diameter (20 microns). Without being bound by any theory, it is believed that the fabric with the fibers formed from the polymer blend provides improved strength, and it is also believed that the fibers with the reduced average diameter have increased contact with other fibers, which also provides improved strength to the fabric.
From
Sample spunbond fabrics were formed with fibers having different average diameters and different percentages of Polymer 1 and Polymer 2, and the fabrics were tested for puncture resistance (according to STM-00483) and grab tensile strength (according to STM-00146). Each fabric was produced as a SMS fabric having two spunbond layers and a meltblown layer laminated (calendered) between the spunbond layers. The weight of each fabric was the same, but the polymer blend, hollowness of the fibers, and average diameter of the fibers was varied in each sample. In this example, the fibers were formed with a two segment spinneret.
The compositions of sample fabrics represented by the diagonally stripped pattern bars and the solid pattern bars are shown in Table 5 below.
From
Sample fabrics were formed with different weights and from fibers having different average diameters and different percentages of Polymer 1 and Polymer 2. Each fabric was produced as a SMS fabric having two spunbond layers and a meltblown layer laminated (calendered) between the spunbond layers. The weight of the meltblown layer was 17 gsm. In this example, the spunbond layer of each sample fabric was formed with a two segment spinneret. The fabrics were tested for puncture resistance (according to STM-00483), grab tensile strength (according to STM-00146), and trapezoidal tear strength (according to STM-00195).
The composition of the samples in this example are shown below in Table 6.
From
A collection of exemplary embodiments (EEs), including at least some explicitly enumerated, providing additional description of a variety of embodiment types in accordance with the concepts described herein are provided below. These examples are not meant to be mutually exclusive, exhaustive, or restrictive; and the invention is not limited to these example embodiments but rather encompasses all possible modifications and variations within the scope of the issued claims and their equivalents.
EE 1. A fiber comprising a fiber body, the fiber body comprising a blend of a first polymer and a second polymer, wherein a melt flow rate (MFR) of the first polymer is greater than a MFR of the second polymer, wherein the blend comprises at least 10% by weight of the second polymer, and wherein the hollow fiber is formed as a spunbond layer on a REICOFIL® III line or on a REICOFIL® IV line.
EE 2. The fiber of any preceding or subsequent exemplary embodiments or combination of exemplary embodiments, wherein the spunbond layer comprising the fiber has an improved mechanical property in at least one of a machine direction or a cross-machine direction compared to a fiber comprising only the first polymer.
EE 3. The fiber of any preceding or subsequent exemplary embodiments or combination of exemplary embodiments, wherein the improved mechanical property comprises at least one of a trap tear strength, a strip tensile strength, a puncture resistance, and a grab tensile strength, and wherein the at least one direction is the machine direction.
EE 4. A spunbond comprising the fiber of any preceding or subsequent exemplary embodiments or combination of exemplary embodiments, wherein a weight of the spunbond layer is less than about 105 gsm.
EE 5. A spunbond non-woven fabric comprising the fiber of any preceding or subsequent exemplary embodiments or combination of exemplary embodiments.
EE 6. The fiber of any preceding or subsequent exemplary embodiments or combination of exemplary embodiments, wherein the fiber body is a hollow and defines a hollow cavity within the fiber body, and wherein the hollow cavity comprises up to about 25% of the fiber body.
EE 7. The fiber of any preceding or subsequent exemplary embodiments or combination of exemplary embodiments, wherein the spunbond layer comprising the fiber is formed with at least one of a two segment spinneret, a three segment spinneret, or a four segment spinneret.
EE 8. A fiber comprising a fiber body extending in a longitudinal direction, the fiber body comprising a blend of a first polymer and a second polymer, wherein a melt flow rate (MFR) of the first polymer is greater than a MFR of the second polymer, wherein the blend comprises at least 10% by weight of the second polymer, and wherein the fiber is formed as a spunbond layer on a REICOFIL® III line or on a REICOFIL® IV line.
EE 9. The fiber of any preceding or subsequent exemplary embodiments or combination of exemplary embodiments, wherein the spunbond layer comprising the fiber has an improved mechanical property in at least one of a machine direction or a cross-machine direction compared to a spunbond fabric comprising a fiber comprising only the first polymer.
EE 10. The fiber of any preceding or subsequent exemplary embodiments or combination of exemplary embodiments, wherein the improved mechanical property comprises at least one of a trap tear strength, a strip tensile strength, a puncture resistance, and a grab tensile strength, and wherein the at least one direction is the machine direction.
EE 11. A spunbond comprising the fiber of any preceding or subsequent exemplary embodiments or combination of exemplary embodiments, wherein a weight of the spunbond layer is less than about 105 gsm.
EE 12. A spunbond non-woven fabric comprising the fiber of any preceding or subsequent exemplary embodiments or combination of exemplary embodiments.
EE 13. The fiber of any preceding or subsequent exemplary embodiments or combination of exemplary embodiments, wherein the fiber body is a hollow and defines a hollow cavity within the fiber body.
EE 14. The fiber of any preceding or subsequent exemplary embodiments or combination of exemplary embodiments, wherein the spunbond layer comprising the fiber is formed with at least one of a two segment spinneret, a three segment spinneret, or a four segment spinneret.
EE 15. A fiber comprising a fiber body, the fiber body comprising a blend of a first polymer and a second polymer, wherein a melt flow rate (MFR) of the first polymer is greater than a MFR of the second polymer, wherein the blend comprises at least 10% by weight of the second polymer, and wherein a spunbond layer of a non-woven fabric comprises the fiber, and wherein the spunbond layer has a weight of less than about 105 gsm.
EE 16. A spunbond comprising the fiber of any preceding or subsequent exemplary embodiments or combination of exemplary embodiments, wherein a weight of a spunbond comprising the fiber is less than about 105 gsm.
EE 17. The fiber of any preceding or subsequent exemplary embodiments or combination of exemplary embodiments, wherein the fiber body is a hollow and defines a hollow cavity within the fiber body.
EE 18. A spunbond non-woven fabric comprising a plurality of fibers, wherein each fiber comprises: a blend of a first polymer and a second polymer, wherein a melt flow rate (MFR) of the first polymer is greater than a MFR of the second polymer, wherein the blend comprises 20%-30% by weight of the first polymer; and a fiber average diameter of from about 15 microns to about 20 microns, and wherein a calendar bond area of the fabric comprises a bond area of from about 15% to about 35%.
EE 19. A hollow fiber comprising a fiber body extending in a longitudinal direction and defining a hollow cavity within the fiber body, wherein the fiber body comprises a blend of a first polymer and a second polymer, wherein a melt flow rate (MFR) of the first polymer is greater than a MFR of the second polymer, and wherein the blend comprises at least 10% by weight of the second polymer.
EE 20. The hollow fiber of any preceding or subsequent exemplary embodiments or combination of exemplary embodiments, wherein the blend comprises 10% to 70% by weight of the second polymer.
EE 21. The hollow fiber of any preceding or subsequent exemplary embodiments or combination of exemplary embodiments, wherein the MFR of the first polymer is greater than 18 g/10 min.
EE 22. The hollow fiber of any preceding or subsequent exemplary embodiments or combination of exemplary embodiments, wherein the MFR of the second polymer is from about 9 g/10 min to about 18 g/10 min.
EE 23. The hollow fiber of any preceding or subsequent exemplary embodiments or combination of exemplary embodiments, wherein the first polymer and the second polymer each comprise a polyolefin.
EE 24. The hollow fiber of any preceding or subsequent exemplary embodiments or combination of exemplary embodiments, wherein the hollow cavity comprises from about 5% to about 40% of the fiber body.
EE 25. The hollow fiber of any preceding or subsequent exemplary embodiments or combination of exemplary embodiments, wherein the hollow cavity comprises from about 10% to about 30% by volume of the fiber body.
EE 26. A spunbond non-woven fabric comprising the hollow fiber of any preceding or subsequent exemplary embodiments or combination of exemplary embodiments.
EE 27. The hollow fiber of any preceding or subsequent exemplary embodiments or combination of exemplary embodiments, further comprising a sheath layer, the sheath layer comprising a third polymer, wherein a MFR of the third polymer is greater than the MFR of the second polymer.
EE 28. The hollow fiber of any preceding or subsequent exemplary embodiments or combination of exemplary embodiments, wherein the MFR of the third polymer is the same as the MFR of the first polymer.
EE 29. The hollow fiber of any preceding or subsequent exemplary embodiments or combination of exemplary embodiments, wherein the third polymer comprises a polyolefin.
EE 30. The hollow fiber of any preceding or subsequent exemplary embodiments or combination of exemplary embodiments, wherein the sheath layer further comprises an additive, and wherein the additive comprises at least one of a fluorochemical, an antimicrobial, a surfactant, and a color pigment.
EE 31. A non-woven fabric comprising the hollow fiber of any preceding or subsequent exemplary embodiments or combination of exemplary embodiments.
EE 32. A hygiene product comprising the spunbond non-woven fabric of any preceding or subsequent exemplary embodiments or combination of exemplary embodiments, wherein the hygiene product comprises at least one of a surgical gown, a drape, gloves, facemasks, and protective apparel, surgical gowns, sterilization wraps, respirators, absorbent pads, wound care products, chemical protection apparel, filtration media, hospital towels, hospital apparel, drapes, gloves, facemasks, sanitary napkins, and diapers.
EE 33. The hollow fiber of any preceding or subsequent exemplary embodiments or combination of exemplary embodiments, wherein the blend further comprises a third polymer.
EE 34. The hollow fiber of any preceding or subsequent exemplary embodiments or combination of exemplary embodiments, wherein the MFR of the third polymer is less than the MFR of the first polymer.
EE 35. The hollow fiber of any preceding or subsequent exemplary embodiments or combination of exemplary embodiments, wherein the MFR of the third polymer is less than the MFR of the second polymer.
EE 36. A method of manufacturing a spunbond layer of a non-woven fabric, the method comprising producing a plurality of fibers by: mixing a first polymer with a second polymer into a blend, wherein a melt flow rate (MFR) of the first polymer is greater than a MFR of the second polymer, and wherein the blend comprises at least 10% by weight of the second polymer; drawing the blend through a spinneret to form the plurality of fibers; quenching the fibers; and depositing the fibers as a web.
EE 37. The method of any preceding or subsequent exemplary embodiments or combination of exemplary embodiments, wherein the blend comprises 10% to 70% by weight of the second polymer.
EE 38. The method of any preceding or subsequent exemplary embodiments or combination of exemplary embodiments, wherein the MFR of the first polymer is greater than 18 g/10 min, and wherein the MFR of the second polymer is from about 9 g/10 min to about 18 g/10 min.
EE 39. The method of any preceding or subsequent exemplary embodiments or combination of exemplary embodiments, wherein the first polymer and the second polymer each comprise a polyolefin.
EE 40. The method of any preceding or subsequent exemplary embodiments or combination of exemplary embodiments, further comprising forming a non-woven fabric with the spunbond layer.
EE 41. The method of any preceding or subsequent exemplary embodiments or combination of exemplary embodiments, wherein forming the non-woven fabric comprises forming a surgical product, wherein the surgical product comprises at least one of a surgical gown, a drape, gloves, facemasks, and protective apparel.
EE 42. A spunbond non-woven fabric comprising a plurality of fibers, wherein the fibers are formed from a polymer blend comprising at least one first polymer and at least one second polymer, wherein a melt flow rate (MFR) of the at least one first polymer is greater than a MFR of the at least one second polymer, wherein the MFR of the at least one second polymer is less than 18 g/10 min, and wherein the blend comprises a percentage by weight of the second polymer that is greater than a percentage by weight of the first polymer.
EE 43. The spunbond non-woven fabric of any preceding or subsequent exemplary embodiments or combination of exemplary embodiments, wherein a weight of the fabric is less than about 105 gsm, and wherein the fabric has a mechanical property in a machine direction that is greater than the mechanical property in the machine direction of a spunbond fabric comprising fibers formed from only the first polymer and under the same conditions, and wherein the mechanical property comprises at least one of a trap tear strength, a strip tensile strength, a puncture resistance, or a grab tensile strength.
EE 44. The spunbond non-woven fabric of any preceding or subsequent exemplary embodiments or combination of exemplary embodiments, wherein the weight of the fabric is from about 8 gsm to about 15 gsm.
EE 45. The spunbond non-woven fabric of any preceding or subsequent exemplary embodiments or combination of exemplary embodiments, wherein the MFR of the at least one first polymer is from greater than 18 g/10 min to about 40 g/10 min.
EE 46. The spunbond non-woven fabric of any preceding or subsequent exemplary embodiments or combination of exemplary embodiments, wherein the fibers each comprise a fiber body that surrounds and defines a cavity, wherein the fiber body and the cavity together define a total volume, and wherein the fibers comprise a hollowness of up to about 25% by volume of the total volume.
EE 47. The spunbond non-woven fabric of any preceding or subsequent exemplary embodiments or combination of exemplary embodiments, wherein the polymer blend comprises 50% to 90% by weight of the at least one second polymer.
EE 48. The spunbond non-woven fabric of any preceding or subsequent exemplary embodiments or combination of exemplary embodiments, wherein an average diameter of each fiber is from about 13 microns to about 22 microns.
EE 49. A non-woven fabric comprising the spunbond non-woven fabric of any preceding or subsequent exemplary embodiments or combination of exemplary embodiments as a first spunbond layer, wherein the non-woven fabric further comprises a second spunbond layer and a meltblown layer laminated between the first spunbond layer and the second spunbond layer, and wherein the second spunbond layer comprises a plurality of fibers, each formed from a polymer blend comprising the at least one first polymer and the at least one second polymer.
EE 50. A spunbond non-woven fabric comprising a plurality of fibers, wherein the fibers are formed from a polymer blend comprising at least one first polymer and at least one second polymer, wherein a melt flow rate (MFR) of the at least one first polymer is from about 19 g/10 min to about 40 g/10 min, wherein a MFR of the at least one second polymer is about 9 g/10 min to about 18 g/10 min, wherein the blend comprises at least 10% by weight of the at least one second polymer, and wherein an average diameter of each fiber is from about 13 microns to about 22 microns.
EE 51. The spunbond non-woven fabric of any preceding or subsequent exemplary embodiments or combination of exemplary embodiments, wherein a weight of the fabric is less than about 105 gsm, and wherein the fabric has a mechanical property in a machine direction that is greater the mechanical property in the machine direction of a spunbond fabric comprising fibers formed from only the first polymer and under the same conditions, and wherein the mechanical property comprises at least one of a trap tear strength, a strip tensile strength, a puncture resistance, or a grab tensile strength.
EE 52. The spunbond non-woven fabric of any preceding or subsequent exemplary embodiments or combination of exemplary embodiments, wherein weight of the spunbond non-woven fabric is from about 42 gsm to about 52 gsm.
EE 53. The spunbond non-woven fabric of any preceding or subsequent exemplary embodiments or combination of exemplary embodiments, wherein the polymer blend comprises 20% to 90% by weight of the at least one second polymer.
EE 54. The spunbond non-woven fabric of any preceding or subsequent exemplary embodiments or combination of exemplary embodiments, wherein the fibers each comprise a fiber body that surrounds and defines a cavity, wherein the fiber body and the cavity together define a total volume, and wherein the fibers comprise a hollowness up to about 25% by volume of the total volume.
EE 55. A non-woven fabric comprising the spunbond non-woven fabric of claim 9 as a first spunbond layer, wherein the non-woven fabric further comprises a second spunbond layer and a meltblown layer laminated between the first spunbond layer and the second spunbond layer, and wherein the second spunbond layer comprises a plurality of fibers formed from a polymer blend comprising the at least one first polymer and the at least one second polymer.
EE 56. A spunbond non-woven fabric comprising a plurality of hollow fibers, wherein the hollow fibers are formed from a polymer blend comprising at least one first polymer and at least one second polymer, wherein a melt flow rate (MFR) of the at least one first polymer is greater than a MFR of the at least one second polymer, wherein the MFR of the at least one second polymer is about 9 g/10 min to less than 18 g/10 min, wherein the blend comprises at least 10% by weight of the second polymer, wherein the hollow fibers each comprise a fiber body that defines a cavity within the fiber body, wherein the cavity and the fiber body together define a total volume, and wherein the fibers comprise a hollowness of at least 5% by volume of the total volume.
EE 57. The spunbond non-woven fabric of claim 14, wherein the fibers comprise a hollowness up to about 40% by volume of the total volume
EE 58. The spunbond non-woven fabric of any preceding or subsequent exemplary embodiments or combination of exemplary embodiments, wherein the polymer blend comprises 20% to 90% by weight of the at least one second polymer.
EE 59. The spunbond non-woven fabric of any preceding or subsequent exemplary embodiments or combination of exemplary embodiments, wherein the MFR of the at least one first polymer is from about 19 g/10 min to about 40 g/10 min.
EE 60. The spunbond non-woven fabric of any preceding or subsequent exemplary embodiments or combination of exemplary embodiments, wherein an average diameter of each fiber is from about 13 microns to about 22 microns.
EE 61. The spunbond non-woven fabric of any preceding or subsequent exemplary embodiments or combination of exemplary embodiments, wherein the at least one first polymer and the at least one second polymer each comprise a polyolefin.
EE 62. The spunbond non-woven fabric of any preceding or subsequent exemplary embodiments or combination of exemplary embodiments, wherein a weight of the spunbond non-woven fabric is less than about 105 gsm, and wherein the spunbond non-woven fabric has an improved mechanical property in a machine direction compared to a spunbond fabric comprising a spunbond non-woven fiber comprising fibers comprising only the first polymer, and wherein the improved mechanical property comprises at least one of a trap tear strength, a strip tensile strength, a puncture resistance, and a grab tensile strength.
The above-described aspects are merely possible examples of implementations, merely set forth for a clear understanding of the principles of the present disclosure. Many variations and modifications can be made to the above-described embodiment(s) without departing substantially from the spirit and principles of the present disclosure. All such modifications and variations are intended to be included herein within the scope of the present disclosure, and all possible claims to individual aspects or combinations of elements or steps are intended to be supported by the present disclosure. Moreover, although specific terms are employed herein, as well as in the claims that follow, they are used only in a generic and descriptive sense, and not for the purposes of limiting the described invention, nor the claims that follow.
This application is a continuation of U.S. application Ser. No. 16/569,394, filed on Sep. 12, 2019 and entitled FIBERS FOR NON-WOVEN FABRICS HAVING BLENDS OF POLYMERS WITH HIGH AND LOW MELT FLOW RATES, which claims the benefit of U.S. Provisional Application No. 62/730,249, filed on Sep. 12, 2018 and entitled HOLLOW FIBERS AND NON-WOVENS WITH BLENDS OF POLYMERS HAVING HIGH AND LOW MELT FLOW RATES, and also claims the benefit of U.S. Provisional Application No. 62/814,355, filed on Mar. 6, 2019 and entitled FIBERS AND NON-WOVENS WITH BLENDS OF POLYMERS HAVING HIGH AND LOW MELT FLOW RATES, all of which are hereby incorporated by reference in their entireties.
| Number | Date | Country | |
|---|---|---|---|
| 62730249 | Sep 2018 | US | |
| 62814355 | Mar 2019 | US |
| Number | Date | Country | |
|---|---|---|---|
| Parent | 16569394 | Sep 2019 | US |
| Child | 17833292 | US |
