Patent Application
20240295050
The presently-disclosed invention relates generally to nonwoven fabrics, and more particularly to bonded nonwoven fabrics exhibiting high loft.
Nonwoven fabrics are used in a variety of applications including personal applications, such as absorbent articles (e.g., diapers and personal hygiene products), residential and commercial construction applications, industrial applications. New products being developed for these applications have demanding performance requirements depending on the intended application. For example, nonwovens have been used in a variety automotive applications including sound dampening. Accordingly, the nonwoven fabrics which are used in these types of products must be engineered to meet these performance requirements.
Despite significant efforts in developing nonwoven fabrics, there is still a need for products exhibiting improvements in sound dampening and mechanical properties without sacrificing other beneficial properties.
Certain embodiments of the invention are directed to nonwoven fabrics having increased thickness and loft. In particular, aspects of the disclosure are directed to a nonwoven fabric comprising a plurality of fibers in which the fibers comprise a polymeric blend of a polymer resin and a high loft additive, and wherein the fabric exhibits a percent increase in thickness of at least 20% in comparison to a similarly prepared nonwoven fabric that does not include the high loft additive.
In certain embodiments, the nonwoven fabric may comprise a meltblown, spunbond, spunlace, resin bonded, air bonded fabric. In a preferred embodiment, the nonwoven fabric comprises a meltblown fabric.
In certain embodiments, the high loft additive comprises a fatty acid amide. For example, the high loft additive has may have following formula (1):
wherein R1 comprises a C10-C22 carbon chain, which may be saturated or unsaturated, and R2, independently, is selected from H, a C1-C4 alkyl group, R1, and R3, wherein R3 has the following formula (2):
—(C1-C4)C(═O)N(R5)(R1) (2)
wherein R5 is H or a C1-C4 alkyl group.
In some embodiments, the high loft additive comprises a fatty acid amide having two amide groups of the general formula (2)
wherein R1, independently, comprises an aliphatic carbon chain having from C10-C22, and R2 is a C1-C4 group, and R4 is selected from —C(═O)NH(R1), —C(═O)N(R1)2, and —C(═O)NH2, —C(═O)N(R5)(R1), and —C(═O)N(R5)2, and wherein R5 is as defined previously.
In certain embodiments, the high loft additive comprises an aliphatic amide having two amide groups of the following formula (4):
wherein each R1, independently, comprises an aliphatic C10-C22 carbon chain, which may be saturated or unsaturated, and R2 comprises a C1-C4 alkyl group. In some embodiments, the fatty acid amide comprises one or more of erucamide, oleamide, and stearamide
behenamide, octadecane amide, ethylene bis-stearamide, and stearyl erucamide. and the like. In a preferred embodiment, the high loft additive comprises an aliphatic bis alkyl amide, such as N, N′-ethylene bis-stearamide. In a preferred embodiment, the fatty acid amide is N, N′-ethylene bis-stearamide.
In certain embodiments, the amount of the high loft additive in the polymeric blend is from about 0.0125 weight percent to about 10 weight percent, such as from about 0.0125 to 2.5 weight percent, based on the total weight of the fiber. In some embodiments, the amount of the high loft additive in the polymeric blend may be from about 0.05 weight percent to about 2.0 weight percent, based on the total weight of the fiber.
In certain embodiments, the fibers of the nonwoven fabric are monocomponent. In some embodiments, the fibers have a sheath/core configuration and the high loft additive is only present in the sheath.
In certain embodiments, the fibers of the nonwoven fabric are not bonded. In some embodiments, the fibers of the nonwoven fabric are thermally bonded, such as air through bonded.
In certain embodiments, the basis weight of the nonwoven fabric is from about 150 to 800 gsm, such as from about 250 to 750 gsm, from about 300 to 750 gsm, from about 350 to 600 gsm, and from about 400 to 550 gsm. In certain embodiments, the nonwoven fabric comprises a meltblown fabric, and wherein the fibers have a mean fiber diameter ranging from about 3.5 to 4.5 microns with a standard deviation of less than 2 microns.
In certain embodiments, nonwoven fabrics in accordance with embodiments of the invention demonstrate improved sound absorbing properties. For example, the nonwoven fabric may exhibit a percent increase in Average Absorption Coefficient (AAC) from 20 to 250% in comparison to a similarly prepared nonwoven fabric that does not include the high loft additive. In some embodiments, the inventive nonwoven fabrics may exhibit a percent increase in Average Absorption Coefficient (AAC) selected from the group consisting of 10 to 220%, 20 to 200%, 30 to 190%, 40 to 80%, 45 to 150%, 80 to 140%, and 45 to 55% in comparison to a similarly prepared nonwoven fabric that does not include the high loft additive.
In certain embodiments, the nonwoven fabric exhibits a percent increase in thickness from about 20 to 250% in comparison to a similarly prepared nonwoven fabric that does not include the high loft additive. For example, the nonwoven fabric may exhibit a percent increase in thickness selected from the group consisting of 20 to 220%, 20 to 200%, 30 to 190%, 40 to 80%, 45 to 150%, 80 to 140%, and 45 to 55% in comparison to a similarly prepared nonwoven fabric that does not include the high loft additive.
In some embodiments, the fibers of the nonwoven fabric comprise a polymer blend in which the polymer resin comprises polypropylene. In some embodiments, the fibers have a sheath/core configuration in which at least one of the sheath or core comprises polypropylene.
In a further aspect, embodiments of the invention are directed to a meltblown nonwoven fabric comprising a plurality of meltblown fibers in which the meltblown fibers comprise a blend of an olefin resin and a fatty acid amide of the following formula (1):
wherein R1 comprises a C10-C22 carbon chain, which may be saturated or unsaturated, and R2, independently, is selected from H, a C1-C4 alkyl group, R1, and R3, wherein R3 has the following formula (2):
—(C1-C4)C(═O)N(R5)(R1) (2)
wherein R5 is H or a C1-C4 alkyl group, and wherein the meltblown nonwoven fabric exhibits a percent increase in thickness of at least 20% in comparison to a similarly prepared nonwoven fabric that does not include the fatty acid amide.
In certain embodiments, the basis weight of the nonwoven fabric is from about 150 to 800 gsm, such as from about 250 to 750 gsm, from about 300 to 750 gsm, from about 350 to 600 gsm, and from about 400 to 550 gsm. In certain embodiments, the nonwoven fabric comprises a meltblown fabric, and wherein the fibers have a mean fiber diameter ranging from about 3.5 to 4.5 microns with a standard deviation of less than 2 microns. In some embodiments, the meltblown nonwoven fabric has a basis weight ranging from about 300 to 650 gsm, and fibers have a mean fiber diameter ranging from about 3.5 to 4.5 microns with a standard deviation of less than 2 microns.
In certain embodiments, the meltblown nonwoven fabric exhibits a percent increase in Average Absorption Coefficient (AAC) from 20 to 250% in comparison to a similarly prepared nonwoven fabric that does not include fatty acid amide.
In certain embodiments, the fatty acid amide having two amide groups of the general formula (2)
wherein R1, independently, comprises an aliphatic carbon chain having from C10-C22, and R2 is a C1-C4 group, and R4 is selected from —C(═O)NH(R1), —C(═O)N(R1)2, and —C(═O)NH2, —C(═O)N(R5)(R1), and —C(═O)N(R5)2, and wherein R5 is as defined previously.
In certain embodiments, the fatty acid amide comprises an aliphatic amide having two amide groups of the following formula (4):
wherein each R1, independently, comprises an aliphatic C10-C22 carbon chain, which may be saturated or unsaturated, and R2 comprises a C1-C4 alkyl group.
In certain embodiments, the fatty acid amide comprises one or more of erucamide, oleamide, and stearamide behenamide, octadecane amide, ethylene bis-stearamide, and stearyl erucamide. In a preferred embodiment of the meltblown nonwoven fabric the fatty acid amide is N, N′-ethylene bis-stearamide.
In some embodiments, amount of the fatty acid amide in the polymeric blend is from about 0.0125 weight percent to about 2.5 weight percent, based on the total weight of the fiber.
In certain embodiments, the olefin resin comprises polypropylene.
Additional aspects of the invention are directed to the use of the inventive nonwoven fabric in the manufacture of a sound absorbing article. Such absorbing articles may be used in automotive vehicles, constructions, such as a building, and household articles, such as appliances.
Additional aspects are also directed to a system and associated method of preparing the inventive nonwoven fabrics.
Having thus described the invention in general terms, reference will now be made to the accompanying drawings, which are not necessarily drawn to scale, and wherein:
The invention now will be described more fully hereinafter with reference to the accompanying drawings, in which some, but not all embodiments of the inventions are shown. Indeed, this inventions may be embodied in many different forms and should not be construed as limited to the embodiments set forth herein; rather, these embodiments are provided so that this disclosure will satisfy applicable legal requirements. Like numbers refer to like elements throughout. As used in the specification, and in the appended claims, the singular forms “a”, “an”, “the”, include plural referents unless the context clearly dictates otherwise.
The terms “first,” “second,” and the like, “primary,” “exemplary,” “secondary,” and the like, do not denote any order, quantity, or importance, but rather are used to distinguish one element from another. Further, the terms “a,” “an,” and “the” do not denote a limitation of quantity, but rather denote the presence of “at least one” of the referenced item.
Each embodiment disclosed herein is contemplated as being applicable to each of the other disclosed embodiments. All combinations and sub-combinations of the various elements described herein are within the scope of the invention.
It is understood that where a parameter range is provided, all integers within that range, and tenths and hundredths thereof, are also provided by the invention. For example, “5-10%” includes 5%, 6%, 7%, 8%, 9%, and 10%; 5.0%, 5.1%, 5.2% . . . 9.8%, 9.9%, and 10.0%; and 5.00%, 5.01%, 5.02% . . . 9.98%, 9.99%, and 10.00%.
As used herein, the terms “about,” “approximately,” and “substantially” in the context of a numerical value or range means ±10% of the numerical value or range recited or claimed, and in particular, encompasses values within a standard margin of error of measurement (e.g., SEM) of a stated value or variations ±0.5%, 1%, 5%, or 10% from a specified value.
For the purposes of the present application, the following terms shall have the following meanings:
The term “fiber” can refer to a fiber of finite length or a filament of infinite length.
As used herein, the term “monocomponent” refers to fibers formed from one polymer or formed from a single blend of polymers. Of course, this does not exclude fibers to which additives have been added for color, anti-static properties, lubrication, hydrophilicity, liquid repellency, etc.
As used herein, the term “multicomponent” refers to fibers formed from at least two polymers (e.g., bicomponent fibers) that are extruded from separate extruders. The at least two polymers can each independently be the same or different from each other, or be a blend of polymers. The polymers are arranged in substantially constantly positioned distinct zones across the cross-section of the fibers. The components may be arranged in any desired configuration, such as sheath-core, side-by-side, pie, island-in-the-sea, and so forth. Various methods for forming multicomponent fibers are described in U.S. Pat. No. 4,789,592 to Taniguchi et al. and U.S. Pat. No. 5,336,552 to Strack et al., U.S. Pat. No. 5,108,820 to Kaneko, et al., U.S. Pat. No. 4,795,668 to Kruege, et al., U.S. Pat. No. 5,382,400 to Pike, et al., U.S. Pat. No. 5,336,552 to Strack, et al., and U.S. Pat. No. 6,200,669 to Marmon, et al., which are incorporated herein in their entirety by reference. Multicomponent fibers having various irregular shapes may also be formed, such as described in U.S. Pat. No. 5,277,976 to Hogle, et al., U.S. Pat. No. 5,162,074 to Hills, U.S. Pat. No. 5,466,410 to Hills, U.S. Pat. No. 5,069,970 to Largman, et al., and U.S. Pat. No. 5,057,368 to Largman, et al., which are incorporated herein in their entirety by reference.
As used herein the terms “nonwoven,” “nonwoven web” and “nonwoven fabric” refer to a structure or a web of material which has been formed without use of weaving or knitting processes to produce a structure of individual fibers or threads which are intermeshed, but not in an identifiable, repeating manner. Nonwoven webs have been, in the past, formed by a variety of conventional processes such as, for example, meltblown processes, spunbond processes, and staple fiber carding processes.
As used herein, the term “meltblown” refers to a process in which fibers are formed by extruding a molten thermoplastic material through a plurality of fine, usually circular, die capillaries into a high velocity gas (e.g. air) stream which attenuates the molten thermoplastic material and forms fibers, which can be to microfiber diameter. Thereafter, the meltblown fibers are carried by the gas stream and are deposited on a collecting surface to form a web of random meltblown fibers. Such a process is disclosed, for example, in U.S. Pat. No. 3,849,241 to Buntin et al.
As used herein, the term “machine direction” or “MD” refers to the direction of travel of the nonwoven web during manufacturing.
As used herein, the term “cross direction” or “CD” refers to a direction that is perpendicular to the machine direction and extends laterally across the width of the nonwoven web.
As used herein, and unless indicated to the contrary, the term “molecular weight” refers to the weight average molecular weight (Mw), and is expressed in grams/mol. The weight average molecular weight can be determined using commonly known techniques, such as gel permeation chromatography (GPC).
As used herein, the term “spunbond” refers to a process involving extruding a molten thermoplastic material as filaments from a plurality of fine, usually circular, capillaries of a spinneret, with the filaments then being attenuated and drawn mechanically or pneumatically. The filaments are deposited on a collecting surface to form a web of randomly arranged substantially continuous filaments which can thereafter be bonded together to form a coherent nonwoven fabric. The production of spunbond non-woven webs is illustrated in patents such as, for example, U.S. Pat. Nos. 3,338,992; 3,692,613, 3,802,817; 4,405,297 and 5,665,300. In general, these spunbond processes include extruding the filaments from a spinneret, quenching the filaments with a flow of air to hasten the solidification of the molten filaments, attenuating the filaments by applying a draw tension, either by pneumatically entraining the filaments in an air stream or mechanically by wrapping them around mechanical draw rolls, depositing the drawn filaments onto a foraminous collection surface to form a web, and bonding the web of loose filaments into a nonwoven fabric. The bonding can be any thermal or chemical bonding treatment, with thermal being typical.
As used herein, the term “air through thermal bonding” involves passing a material such as one or more webs of fibers to be bonded through a stream of heated gas, such as air, in which the temperature of the heated gas is above the softening or melting temperature of at least one polymer component of the material being bonded. Air through thermal bonding may involve passing a material through a heated oven.
As used herein “thermal point bonding” involves passing a material such as one or more webs of fibers to be bonded between a heated calender roll and an anvil roll. The calender roll is typically engraved with a pattern so that the fabric is bonded in discrete point bond sites rather than being bonded across its entire surface.
As used herein, the term “bond density” refers to the number of individual bond points in a given surface area of the nonwoven fabric.
As used herein the term “polymer” generally includes, but is not limited to, homopolymers, copolymers, such as, for example, block, graft, random and alternating copolymers, terpolymers, etc. and blends and modifications thereof. Furthermore, unless otherwise specifically limited, the term “polymer” shall include all possible geometrical configurations of the material, including isotactic, syndiotactic and random symmetries.
Certain embodiments of the invention are directed to a nonwoven fabric exhibiting increased loft in which at least some of the fibers of the nonwoven comprise a blend of a polymer resin and a high loft additive. In one embodiment, the present invention provides a nonwoven fabric comprising a plurality of fibers wherein the plurality fibers comprise a blend of a polymeric resin and at least one high loft additive. As explained in greater detail below, the inclusion of the high loft additive in the polymer resin improves the loft (e.g., thickness) of the fabric in comparison to an identical fabric that does not include the high loft additive.
In addition to increases in loft of the nonwoven fabric, it has also been discovered that the inclusion of the high loft additive also increases the sound absorption properties of the nonwoven fabric.
With reference to
In certain embodiments, the high loft additive comprises an aliphatic fatty acid amide having at least one amide group and at least one aliphatic carbon chain having from 10 to 22 carbon atoms. In particular, the high loft additive includes fatty acid amides of the general formula (1):
where R1 comprises a C10-C22 carbon chain, which may be saturated or unsaturated and aliphatic, and R2, independently, is selected from H, a C1-C4 alkyl group. R1, and R3, with R3 having the following formula (2):
—(C1-C4)C(═O)N(R5)(R1) (2)
wherein R5 is H or a C1-C4 alkyl group. In a preferred embodiment, R5 is H.
The a C10-C22 carbon chain of R1 is generally linear although some chains may include some minor branching (e.g., C1-C4 side chain branching). Typically, the R1 carbon chain will have from 10 to 22 carbon atoms, with a chain length of 14 to 20 carbon atoms being somewhat more preferred, and a chain length of 16 to 18 carbon atoms being most preferred.
In some embodiments, R1 may include from 1 to 4 vinyl groups, 1 to 3 vinyl groups, 1 to 2 vinyl groups, and in particular, a single vinyl groups. In certain preferred embodiments. R1 is saturated and does not include any vinyl groups.
The amide group of formula (1) may be primary, secondary, or tertiary. In a preferred embodiment, the amide group is a secondary amide.
In certain embodiments, the high loft additive comprises a fatty acid amide having two amide groups of the general formula (3)
where R1, independently, comprises an aliphatic carbon chain having from C10-C22, and R2 is a C1-C4 group, and R4 is selected from —C(═O)NH(R1), —C(═O)N(R1)2, and —C(═O)NH2, —C(═O)N(R5)(R1), and —C(═O)N(R5)2 where R5 is as defined previously.
The aliphatic C10-C22 carbon chain of R1 is generally linear although some chains may include some minor branching (e.g., C1-C4 side chain branching). Typically, the C10-C22 chain will have from 10 to 18 carbon atoms, with an chain length of 14 to 20 carbon atoms being somewhat more preferred, and a chain length of 16 to 18 carbon atoms being most preferred. In the compound of formula (3), R1 may be the same or different. As noted previously, R1 may include 1 to 4 vinyl groups, and may include some minor branching (e.g., C1-C4 side chain branching). In a preferred embodiment, R1 is saturated and does not include any vinyl groups. In addition, R1 preferably does not include any branching.
In a preferred embodiment, the high loft additive comprises an aliphatic amide having two amide groups of the following formula (4):
wherein each R1, independently, comprises an aliphatic C10-C22 carbon chain, which may be saturated or unsaturated, and R2 comprises a C1-C4 alkyl group. In certain embodiments of the compound of formula (4), the two R1 groups are identical, and in other embodiments, the two R1 groups are different from each other. In a preferred embodiment of formula (4), R1 comprises a saturated aliphatic carbon chain having 14 to 18 carbon atoms. As discussed above, in certain embodiments R1 may include 1 to 4 vinyl groups, and may include some minor branching (e.g., C1-C4 side chain branching). In a preferred embodiment, R1 is saturated and does not include any vinyl groups. In addition, R1 preferably does not include any branching.
In certain embodiments of the compound of formula (4), R1 is selected from the group consisting of a methyl group, ethyl group, propyl group, and butyl group. In a preferred embodiment. R2 is an ethyl group.
Examples of suitable fatty acid amides may include one or more of erucamide, oleamide, and stearamide behenamide, octadecane amide, ethylene bis-stearamide, stearyl erucamide, and the like. In a preferred embodiment, the high loft additive comprises an aliphatic bis alkyl amide, such as N, N′-ethylene bis-stearamide. Commercial examples of such ethylene bis-stearamides may be obtained from CRODA Polymer Additives under the product name CRODAMIDE™ EBS and Sigma-Aldrich under the product number 434671.
Generally, it may be desirable for the high loft additive to have a melting temperature below the melting temperature of the polymer resin in which the high loft additive is blended and a decomposition temperature above the melting temperature of the polymer resin.
In certain embodiments, high loft additive may be provided in a masterbatch carrier resin. For example, in one embodiment, the high loft additive is provided in a polymer carrier resin that is blended with the polymer resin prior to spinning of the fibers.
Typically, the amount of high loft additive in the polymer resin masterbatch is from about 1 to 25 weight percent based on the total weight of the masterbatch, with an amount from 2 to 20 weight percent being somewhat more typical. The masterbatch may also include additional additives, such as one or more compatibilizers. A commercial example of a high loft additive that may be used in embodiments of the disclosure includes a EBS masterbatch available from Sandridge Color Corporation under the product number 22188, which is an ethylene bis-stearamide in a polypropylene masterbatch.
A wide variety of different polymer resins may be used to prepare nonwoven fabrics in accordance with embodiments of the invention. As discussed in greater detail below, the polymers may be so-called synthetic polymers, bio-polymers, or may include blends of polymers.
The amount of the high loft additive in the fibers will generally depend on where the high loft additive is present in the structure of the fibers, and the final desired properties of the nonwoven fabric. In general, the amount of the high loft additive may range from about 0.0125 weight percent to about 10 weight percent, based on the total weight of the polymeric component of the fiber in which the high loft additive is present. In one embodiment, the concentration of the fatty acid amide may range from about 0.1 to 6 weight percent, such as 0.2 to 3, weight percent, based on the total weight of the polymeric component of the fiber in which the high loft additive is present. In preferred embodiments, the concentration of the fatty acid amide may range from about 0.1 to 2 weight percent, more preferably from about 0.2 to 1.5 weight percent, and even more preferable 0.3 to 1.25 weight percent, with 0.8 to 1.2 weight percent, based on the total weight of the polymeric component of the fiber in which the high loft additive is present.
For example, in monocomponent fibers the weight percent of the high loft additive in the fibers will be based on the total weight of the fiber. In such a case, the amount high loft additive may range from about 0.0125 weight percent to about 2.5 weight percent, based on the total weight of the fiber. However, in the case of a bicomponent fiber, the weight percent of the high loft additive will be based on the total weight of the component in which the high loft additive is present. For example, in the case of a bicomponent fiber having a sheath to core weight ratio of 30:70, and in which the high loft additive is only present in the sheath, the weight percent of the high loft additive in the fiber may range from about 0.0125 weight percent to about 2.5 weight percent, based on the total weight of the sheath, which results in a weight percent of the high loft additive that is from 0.00375 to 0.750, based on the total weight of the fiber.
In one embodiment, the amount of the high loft additive may be at least about any one of the following: at least 0.0125, at least 0.0250, at least 0.0375, at least 0.050, at least 0.0625, at least 0.075, at least 0.100, at least 0.125, at least 0.150, at least 0.1875, at least 0.2, at least 0.2475, at least 0.25, at least 0.3 at least 0.375, at least 0.40, at least 0.495, at least 0.50, at least 0.60, at least 0.80, at least 0.9904, at least 1.0, at least 1.25, at least 1.2375, at least 1.5, at least 1.875, at least 2.0, at least 2.5, at least 3.0, at least 3.5, at least 4.0, at least 4.5, at least 5.0, at least 5.5, at least 6.0, at least 6.5, at least 7.0, at least 7.5, at least 8.0, at least 8.5, at least 9.0, at least 9.5, at least 9.6, at least 9.7, at least 9.8, and at least 9.9, based on the total weight of the polymeric component of the fiber in which the high loft additive is present.
In other embodiments, the amount of high loft additive may be less than about any one of the following: 0.0250, 0.0375, 0.050, 0.0625, 0.075, 0.100, 0.125, 0.150, 0.1875, 0.2, 0.2475, 0.25, 0.3, 0.375, 0.40, 0.495, 0.50, 0.60, 0.80, 0.9904, 1.0, 1.25, 1.2375, 1.5, 1.875, 2.0, 2.5, 3.0, 3.5, 4.0, 4.5, 5.0, 5.5, 6.0, 6.5, 7.0, 7.5, 8.0, 8.5, 9.0, 9.5 and 10 weight percent. It should also be recognized that the amount of the high loft additive present in a polymer component of the fiber also encompasses ranges between the aforementioned amounts.
In certain embodiments, the fibers have a bicomponent structure in which the core and sheath both comprise the same type of polymer, and the sheath includes the high loft additive that is present in an amount that is from about 0.1 to 1 weight percent, based on the total weight of the sheath component, and in particular, from about 0.1 to 0.75, and more particularly from about 0.2 to 0.6 weight percent, and even more particularly, from about 0.3 to 0.4 weight percent, based on the total weight of the sheath component. Although, the high loft additive has generally discussed as being present in a monocomponent fiber or the sheath of a bicomponent fiber, it should be recognized that other arrangements are within the embodiments of the present invention. For example, the high loft additive may be present in only the core and not the sheath of a bicomponent fiber, or the high loft additive may be present in both the sheath and the core.
As the amount of the High Loft Additive in the fibers may vary depending on the amount of the high loft additive in the masterbatch polymer, the structure of the fiber (e.g., monocomponent or bicomponent), and in the case of the bicomponent, the ratio of a first polymer component to a second component in the fiber, the following tables provide exemplary ranges of the high loft additive in various fiber structures and at various loadings of the high loft additive in the masterbatch polymer, and at various loadings of the masterbatch in the polymer carrier resin.
In accordance with certain embodiments, the basis weight of the nonwoven fabric may vary depending on the end use application of the fabric. For example, in embodiments directed to absorbent articles, such as diapers and hygiene products, garments, wound care, and the like, the basis weights of the nonwoven fabric may generally from about 5 grams per square meter (gsm) to about 200 gsm.
In some embodiments, for instance, the fabric may have a basis weight from about 8 gsm to about 70 gsm. In certain embodiments, for example, the fabric may comprise a basis weight from about 10 gsm to about 50 gsm. In further embodiments, for instance, the fabric may have a basis weight from about 11 gsm to about 30 gsm. As such, in certain embodiments, the fabric may have a basis weight from at least about any of the following: 7, 8, 9, 10, and 11 gsm and/or at most about 150, 100, 70, 60, 50, 40, and 30 gsm (e.g., about 9-60 gsm, about 11-40 gsm, etc.).
In embodiments where higher basis weights are desired, for example in industrial, construction, agricultural, and the like, the nonwoven fabric may have basis weights ranging from about from about 150 to 800 gsm, from about 200 to 800 gsm, such as 250 to 750 gsm, 300 to 700 gsm, 350 to 650 gsm, and 400 to 600 gsm.
According to certain embodiments, for example, the fibers may have a linear mass density from about 1 dtex to about 5 dtex. In other embodiments, for instance, the fibers may have a dtex from about 1.5 dtex to about 3 dtex. In further embodiments, for example, the fibers may have a linear mass density from about 1.6 dtex to about 2.5 dtex. As such, in certain embodiments, the fibers have a linear mass density from at least about any of the following: 1, 1.1, 1.2, 1.3, 1.4, 1.5, and 1.6 dtex and/or at most about 5, 4.5, 4, 3.5, 3, and 2.5 dtex (e.g., about 1.4-4.5 dtex, about 1.6-3 dtex, etc.).
Advantageously, the inventors of the present invention have discovered that the addition of the high loft additive in the fibers provides significant increases in nonwoven fabric loft in comparison to an identical or similarly prepared nonwoven fabric that does not include the high loft additive. In this regard, nonwoven fabrics in accordance with embodiments of the present invention may exhibit an increase in thickness that are at least 10% greater in comparison to a similarly prepared nonwoven fabric that does not include the high loft additive. In some embodiments, the nonwoven fabric may exhibit an increase in thickness (caliper or loft) that is from 50% to 200% greater than the thickness of a similarly prepared nonwoven fabric that does not include the high loft additive. By “similarly prepared” or “similar nonwoven” it is meant that the nonwoven fabrics have identical chemistry or substantially identical chemistry and have been processed under similar or identical processing conditions, with the exception of the addition of the high loft additive in the inventive nonwoven fabrics.
In certain embodiments, nonwoven fabrics in accordance with embodiment the invention exhibit an increase in thickness (caliper) ranging from 10 to 1,000%, and in particular, from about 20 to 500%, and more particularly, from 100 to 250% in comparison to a similar nonwoven fabric in which the similar nonwoven comprises fibers that do not include the high loft additive.
In certain embodiments, the inventive nonwoven fabrics may exhibit an increase in thickness that is from about 10 to 1000% in comparison to a similarly prepared nonwoven fabric that does not include the high loft additive. In a preferred embodiment, the inventive nonwoven fabric may exhibit an increase in thickness that is from about 80 to 500%, and more preferably, from about 140 to 480% in comparison to a similarly prepared nonwoven fabric that does not include the high loft additive. For example, the inventive nonwoven fabric may exhibit an increase in thickness of any one or more of at least 10%, at least 20%, at least 30%, at least 40%, at least 50%, at least 60%, at least 70%, at least, 80%, at least 90%, at least 100%, at least 125%, at least 150%, at least 175%, at least 200%, at least 225%, at least 250%, at least 275%, at least 300%, at least 325%, at least 350%, at least 375%, at least 400%, at least 425%, at least 450%, at least 475%, at least 500%, at least 525%, at least 550%, at least 575%, at least 600%, at least 625%, at least 650%, at 675%, at least 700%, at least 725%, at least 750%, at least 775%, at least 800%, at least 825%, at least 850%, at least 875%, at least 900%, at least 925%, at least 950, at least 975%, or at least 1,000%, in comparison to a similarly prepared nonwoven fabric that does not include the high loft additive.
In one embodiment, the present disclosure provides a meltblown nonwoven fabric comprising a plurality of fibers that are thermally bonded to each other to form a coherent web.
Although, specific examples of nonwoven fabrics are generally discussed in the context of meltblown fabrics prepared from meltblown fibers, it should be recognized that other nonwoven fabrics and fibers may be prepared in accordance with embodiments of the invention including spunblown fibers and spunblown fabrics, staple fibers and carded fabric, wet-laid fabrics, resin bonded fabrics, and air-laid fabrics, and combinations thereof.
In certain embodiments, the fibers of the nonwoven fabric may comprise monocomponent fibers, multicomponent fibers, or combinations thereof. In a preferred embodiment, the fibers are monocomponent.
In one embodiment, the fibers of the nonwoven fabric comprise multicomponent fibers that may include at least two polymer components arranged in structured domains across the cross section of the fiber. As is generally well known to those skilled in the art, polymer domains or components are arranged in substantially continuously positioned zones across the cross-section of the multicomponent fiber and extend continuously along the length of the multicomponent fiber. More than two components could be present in the multicomponent fiber.
In certain embodiments, the configuration of multicomponent fibers is a side-by-side arrangement wherein a first polymer component defines a first continuous distinct zone extending along the length of the fiber, and a second polymer component defines a second continuous distinct zone extending along the length of the fiber. Both the first and second polymer components define at least a portion of the outer surface of the continuous fibers. In certain embodiments, the first and second distinct zones of the side-by-side continuous fibers are present in ratios ranging from 10:90 to 90:10, and in particular, from about 40:60 to 60:40, and more particularly, from about 50:50. Side-by-side configurations are particularly useful in the preparation of crimped fibers. Other configurations that may be useful in the preparation of crimped fibers include eccentric sheath/core and D-centric sheath core configurations.
A preferred configuration is a sheath/core arrangement wherein a first component, the sheath, substantially surrounds a second component, the core. The resulting sheath/core bicomponent fiber may have a round or non-round cross-section. Other structured fiber configurations as known in the art can be used including, segmented pie, islands-in-the-sea and tipped multilobal structures.
In certain embodiments, the fibers are bicomponent in which a first polymer component defines a sheath of the fiber, and a second polymer component defines a core of the fiber. Generally, the weight percentage of the sheath to that of the core in the fibers may vary widely depending upon the desired properties of the nonwoven fabric. For example the weight ratio of the sheath to the core may vary between about 5:95 to 95:5, such as from about 10:90 to 90:10, and in particular from about 20:80 to 80:20. In a preferred embodiment, the weight ratio of the sheath to the core is about 25:75 to 35:65, with a weight ratio of about 30:70 to 50:50 being preferred.
Preferred sheath/core bicomponent fibers for use in making fabrics of this invention can have the higher melting component as the core and the lower melting component as the sheath. For example, a lower melting point polymer component could be used as the sheath and the core could be a higher melting polymer component comprising a polyolefin, such as polypropylene. Such a structure with a lower melting point polymer on the surface allows use of a reduced bonding temperatures, such as air through bonding temperatures or calender oil bonding temperatures, thus conserving energy during manufacture of the nonwoven web.
In one example, the sheath comprising a first polypropylene having a first melting temperature that is lower than a second polypropylene comprising the core. Typically, the first polypropylene of the sheath has a melting point at least 10° C. than the second polypropylene comprising the core.
In a further example of a bicomponent fiber, an aliphatic polyester component, such as polylactic acid, could be used as the sheath and the core could be a higher melting polymer component comprising a polyolefin, such as polypropylene. Such a structure with an aliphatic polyester on the surface allows use of a reduced bonding temperatures as noted previously.
A wide variety of polymers may be used in the preparation of nonwoven fabrics in accordance with embodiments of the present disclosure.
Nonwoven fabrics in accordance with embodiments of the invention may be prepared with a wide variety of different polymers and polymeric blends. Examples of suitable polymers for preparing the fibers include polyolefins, such as polypropylene and polyethylene, and copolymers thereof, polyesters, such as polyethylene terephthalate (PET), polytrimethylene terephthalate (PIT), and polybutylene terephthalate (PBT), nylons, polystyrenes, polyurethanes, copolymers, and blends thereof, and other synthetic polymers that may be used in the preparation of fibers. In some embodiment, the polymer can be selected from the group consisting of: polyolefins, polyesters, polyethylene terephthalates, polybutylene terephthalates, polycyclohexylene dimethylene terephthalates, polytrimethylene terephthalates, polymethyl methacrylates, polyamides, nylons, polyacrylics, polystyrenes, polyvinyls, polytetrafluoroethylenes, ultrahigh molecular weight polyethylenes, very high molecular weight polyethylenes, high molecular weight polyethylenes, polyether ether ketones, non-fibrous plasticized celluloses, polyethylenes, polypropylenes, polybutylenes, polymethylpentenes, low-density polyethylenes, linear low-density polyethylenes, high-density polyethylenes, polystyrenes, acrylonitrile-butadiene-styrenes, styrene-acrylonitriles, styrene tri-block and styrene tetra block copolymers, styrene-butadienes, styrene-maleic anhydrides, ethylene vinyl acetates, ethylene vinyl alcohols, polyvinyl chlorides, cellulose acetates, cellulose acetate butyrates, plasticized cellulosics, cellulose propionates, ethyl cellulose, natural fibers, any derivative thereof, any polymer blend thereof, any copolymer thereof or any combination thereof.
In certain embodiments, the polymers for use in the fibers preferably comprise a polyolefin, such as a polypropylene, polyethylene, a blend of a polypropylene and polyethylene, and combinations thereof.
A wide variety of polypropylenes may be used in embodiments of the invention typically have molecular weights greater than about 120,000 g/mol, and more typically, may have molecular weights ranging from about 150,000 to about 300,000 g/mol. In one embodiment, the polypropylene may have a molecular weights ranging from about 160,000 to about 250,000 g/mol, and in particular, from about 160,000 to about 180,000 g/mol.
In certain embodiments for the preparation of spunbond fibers, polypropylenes that may be used have an MFR that is typically from about 10 to 100 g/10 min, and in particular, from about 20 to 40 g/10 min, with an MFR from about 22 to 38 g/10 min being somewhat more typical. Unless otherwise indicated MFR is measured in accordance with ASTM D-1238.
Examples of such polypropylenes may include those available from ExxonMobil, such as PP3155 (36 MFR g/10 min, density of 0.90 g/cm3, and Mw 172 k g/mol); PP3155E5 (36 MFR g/10 min, density of 0.90 g/cm3, and Mw 172 k g/mol); and ACHIEVE™ 3854 (24 MFR g/10 min, density of 0.90 g/cm3). Polypropylenes available from SABIC®, such as SABIC PP 511A (25 MFR g/10 min, density of 0.905 g/cm3), polypropylenes available from Borealis, such as HG475FB (27 MFR g/10 min), and polypropylenes available from Braskem, such as CP360H (34 MFR g/10 min) may also be used.
In certain embodiments for the preparation of meltblown fibers, polypropylenes that may be used have an MFR that is typically greater than about 500 g/10 min. For example, the polypropylene may have an MFR from about 500 to 2,500 g/10 min, and in particular, from about 1000 to 1500 g/10 min, with an MFR from about 1200 to 1400 g/10 min being somewhat more typical. An example of such a polypropylene is available from Braskem, such as H155 (1250 MFR) g/10 min.
In certain embodiments, the fibers may comprise a multicomponent fiber, such as a bicomponent fiber comprising a first polymer component and a second polymer component in which the second polymer component comprises a blend of polyolefins in which a first polyolefin in the blend has a low MFR, such as less than 100 g/10 min and the second polyolefin in the blend has an MFR greater than the first polyolefin, such as greater than 500 g/10 min, and in particular, greater than 1,000 g/10 min. Typically, the MFR of the blend is less than 50 g/10 min and the MFR ratio of the low MFR polyolefin to the high MFR polyolefin is 1:100, and in particular: 1:20 to 1:50. Typically, the amount of high MFR in the blend is from about 0.5 to 12 weight percent, based on the total weight of the blend, and in particular, from about 2 to 8, weight percent, and more particularly, from about 3 to 6 weight percent, based on the total weight of the blend.
In one such embodiment, the first polymer component comprises a polypropylene polymer having an MFR from about 20 to 40 g/10 min, and the second polymer component comprises a blend of a low MFR polypropylene having an MFR from about 20 to 40 g/10 min and a high MFR polypropylene having an MFR from about 500 to 2,500 g/10 min in which the amount of high MFR polypropylene in the blend is from about 3 to 6 weight percent, based on the total weight of the blend. The polypropylene in the first polymer component may be the same or a different polypropylene as the low MFR polypropylene in the second polymer component. Such fibers when prepared in a side-by-side, eccentric or D-centric configuration may be used to prepare a nonwoven fabric comprising crimped fibers.
In some embodiments, the polyolefin may comprise a polyethylene polymer. Various types of polyethylene polymers may be employed in the fibers of the present invention. As an example, a high density polyethylene, a branched (i.e., non-linear) low density polyethylene, or a linear low density polyethylene (LLDPE) can be utilized. Polyethylenes may be produced from any of the well-known processes, including metallocene and Ziegler-Natta catalyst systems. Generally, the polyethylene polymers that are conventionally used in the production of spunbond fabrics may be suitable for use in the present invention.
In one embodiment of the invention, the polyethylene component comprises a polyethylene having a density ranging from about 0.90 to 0.97 g/cm3 (ASTM D-792). In particular, preferred polyethyelenes have a density value ranging from 0.93 to 0.965 g/cm3, and more particularly from about 0.94 to 0.965 g/cm3. Examples of suitable polyethylenes included ASPUN™ 6834 (a polyethylene polymer resin having a melt index of 17 g/10 min (ISO 1133) and a density of 0.95 g/cm3 (ASTM D-792)), available from Dow Chemical Company, and HD6908.19 (a polyethylene resin supplied by ExxonMobil having a melt index in the range of 7.5 to 9 g/10 min (ISO 1133) and a density of 0.9610 to 0.9680 g/cm3 (ASTM D-792)).
LLDPE may also be used in some embodiments of the present invention. LLDPE is typically produced by a catalytic solution or fluid bed process under conditions established in the art. The resulting polymers are characterized by an essentially linear backbone. Density is controlled by the level of comonomer incorporated into the otherwise linear polymer backbone. Various alpha-olefins are typically copolymerized with ethylene in producing LLDPE. The alpha-olefins which preferably have four to eight carbon atoms, are present in the polymer in an amount up to about 10 percent by weight. The most typical comonomers are butene, hexene, 4-methyl-1-pentene, and octene. In general, LLDPE can be produced such that various density and melt index properties are obtained which make the polymer well suited for melt-spinning with polypropylene. Preferably, the LLDPE should have a melt index of greater than 10, and more preferably 15 or greater for spunbonded filaments. Particularly preferred are LLDPE polymers having a density of 0.90 to 0.97 g/cm3 and a melt index of greater than 25. Examples of suitable commercially available linear low density polyethylene polymers include those available from Dow Chemical Company, such as ASPUN™ Type 6811 (27 MFR g/10 min, density 0.923 g/cm3), ASPUN™ Type 6834 (17 MFR g/10 min, density of 0.95 g/cm3), ASPUN™ Type 6000 (30 MFR g/10 min, 0.955 g/cm3 density), ASPUN™ Type 6850 (30 MFR g/10 min, 0.955 g/cm3 density), Dow LLDPE 2500 (55 MFR g/10 min, 0.923 g/cm3 density), Dow LLDPE Type 6808A (36 MFR g/10 min, 0.940 g/cm3 density), and the Exact series of linear low density polyethylene polymers from Exxon Chemical Company, such as Exact 2003 (31 MFR g/10 min, density 0.921 g/cm3).
In some embodiments, the polymers may be extensible and/or elastic.
In some embodiments, the polymers may comprise polymers derived from mechanically or chemically recycled feedstocks. For example, up to 100% of the polymer comprising the nonwoven fabric may be derived from recycled polymers.
In further embodiments, nonwoven fabrics nonwoven fabrics in accordance with one or more embodiments of the invention may be prepared from bio-based materials, and in particular, from bio-based polymers. In contrast to polymers derived from petroleum sources, bio-based polymers are generally derived from a bio-based material. In some embodiments, a bio-based polymer may also be considered biodegradeable. A special class of biodegradable product made with a bio-based material might be considered as compostable if it can be degraded in a composting environment. The European standard EN 13432. “Proof of Compostability of Plastic Products” may be used to determine if a fabric or film comprised of sustainable content could be classified as compostable.
In one such embodiment, the nonwoven fabric comprises fibers comprising a bio-based polymer. In certain embodiments, the fibers are substantially free of synthetic materials, such as petroleum-based materials and polymers. For example, fibers comprising the nonwoven fabric may have less than 25 weight percent of materials that are non-bio-based, and more preferably, less than 20 weight percent, less than 15 weight percent, less than 10 weight percent, and even more preferably, less than 5 weight percent of non-bio-based materials, based on the total weight of the nonwoven fabric.
In certain embodiments, the nonwoven fabric may comprise fibers comprising a bio-based polymer and a polymer derived from a petroleum source.
In one embodiment, bio-based polymers for use may include aliphatic polyester based polymers, such as polylactic acid, and bio-based derived polyethylene.
Aliphatic polyesters useful in the present invention may include homo- and copolymers of poly(hydroxyalkanoates), and homo- and copolymers of those aliphatic polyesters derived from the reaction product of one or more polyols with one or more polycarboxylic acids that are typically formed from the reaction product of one or more alkanediols with one or more alkanedicarboxylic acids (or acyl derivatives). Polyesters may further be derived from multifunctional polyols, e.g. glycerin, sorbitol, pentaerythritol, and combinations thereof, to form branched, star, and graft homo- and copolymers. Polyhydroxyalkanoates generally are formed from hydroxyacid monomeric units or derivatives thereof. These include, for example, polylactic acid, polyhydroxybutyrate, polyhydroxyvalerate, polycaprolactone and the like. Miscible and immiscible blends of aliphatic polyesters with one or more additional semicrystalline or amorphous polymers may also be used.
One useful class of aliphatic polyesters are poly(hydroxyalkanoates), derived by condensation or ring-opening polymerization of hydroxy acids, or derivatives thereof. Suitable poly(hydroxyalkanoates) may be represented by the formula: H(O—R—C(O)—)nOH where R is an alkylene moiety that may be linear or branched having 1 to 20 carbon atoms, preferably 1 to 12 carbon atoms optionally substituted by catenary (bonded to carbon atoms in a carbon chain) oxygen atoms; n is a number such that the ester is polymeric, and is preferably a number such that the molecular weight of the aliphatic polyester is at least 10,000, preferably at least 30,000, and most preferably at least 50,000 daltons. In certain embodiments, the molecular weight of the aliphatic polyester is typically less than 1,000,000, preferably less than 500,000, and most preferably less than 300,000 daltons. R may further comprise one or more caternary (i.e. in chain) ether oxygen atoms. Generally, the R group of the hydroxy acid is such that the pendant hydroxyl group is a primary or secondary hydroxyl group.
Useful poly(hydroxyalkanoates) include, for example, homo- and copolymers of poly(3-hydroxybutyrate), poly(4-hydroxybutyrate), poly(3-hydroxyvalerate), poly(lactic acid) (as known as polylactide), poly(3-hydroxypropanoate), poly(4-hydropentanoate), poly(3-hydroxypentanoate), poly(3-hydroxyhexanoate), poly(3-hydroxyheptanoate), poly(3-hydroxyoctanoate), polydioxanone, polycaprolactone, and polyglycolic acid (i.e. polyglycolide). Copolymers of two or more of the above hydroxy acids may also be used, for example, poly(3-hydroxybutyrate-co-3-hydroxyvalerate), poly(lactate-co-3-hydroxypropanoate), poly(glycolide-co-p-dioxanone), and poly(lactic acid-co-glycolic acid). Blends of two or more of the poly(hydroxyalkanoates) may also be used, as well as blends with one or more semicrystalline or amorphous polymers and/or copolymers.
The aliphatic polyester may be a block copolymer of poly(lactic acid-co-glycolic acid). Aliphatic polyesters useful in the inventive compositions may include homopolymers, random copolymers, block copolymers, star-branched random copolymers, star-branched block copolymers, dendritic copolymers, hyperbranched copolymers, graft copolymers, and combinations thereof.
Another useful class of aliphatic polyesters includes those aliphatic polyesters derived from the reaction product of one or more alkanediols with one or more alkanedicarboxylic acids (or acyl derivatives). Such polyesters have the general formula:
where R′ and R″ each represent an alkylene moiety that may be linear or branched having from 1 to 20 carbon atoms, preferably 1 to 12 carbon atoms, and m is a number such that the ester is polymeric, and is preferably a number such that the molecular weight of the aliphatic polyester is at least 10,000, preferably at least 30,000, and most preferably at least 50,000 daltons, but less than 1,000,000, preferably less than 500,000 and most preferably less than 300,000 daltons. Each n is independently 0 or 1. R′ and R″ may further comprise one or more caternary (i.e. in chain) ether oxygen atoms.
Examples of aliphatic polyesters include those homo- and copolymers derived from (a) one or more of the following diacids (or derivative thereof): succinic acid; adipic acid; 1,12 dicarboxydodecane; fumaric acid; glutartic acid; diglycolic acid; and maleic acid; and (b) one of more of the following diols: ethylene glycol; polyethylene glycol; 1,2-propane diol; 1,3-propanediol; 1,2-propanediol; 1,2-butanediol; 1,3-butanediol; 1,4-butanediol; 2,3-butanediol; 1,6-hexanediol; 1,2 alkane diols having 5 to 12 carbon atoms; diethylene glycol; polyethylene glycols having a molecular weight of 300 to 10,000 daltons, and preferably 400 to 8,000 daltons; propylene glycols having a molecular weight of 300 to 4000 daltons; block or random copolymers derived from ethylene oxide, propylene oxide, or butylene oxide; dipropylene glycol; and polypropylene glycol, and (c) optionally a small amount, i.e., 0.5-7.0 mole percent of a polyol with a functionality greater than two, such as glycerol, neopentyl glycol, and pentaerythritol.
Such polymers may include polybutylene succinate homopolymer, polybutylene adipate homopolymer, polybutyleneadipate-succinate copolymer, polyethylenesuccinate-adipate copolymer, polyethylene glycol succinate homopolymer and polyethylene adipate homopolymer.
Commercially available aliphatic polyesters include poly(lactide), poly(glycolide), poly(lactide-co-glycolide), poly(L-lactide-co-trimethylene carbonate), poly(dioxanone), poly(butylene succinate), and poly(butylene adipate).
The term “aliphatic polyester” covers—besides polyesters which are made from aliphatic and/or cycloaliphatic components exclusively also polyesters which contain besides aliphatic and/or cycloaliphatic units, aromatic units, as long as the polyester has substantial bio-based content.
In addition to PLA based resins, nonwoven fabrics in accordance with embodiments of the invention may include other polymers derived from an aliphatic component possessing one carboxylic acid group and one hydroxyl group, which are alternatively called polyhydroxyalkanoates (PHA). Examples thereof are polyhydroxybutyrate (PHB), poly-(hydroxybutyrate-co-hydroxyvalerate) (PHBV), poly-(hydroxybutyrate-co-polyhydroxyhexanoate) (PHBH), polyglycolic acid (PGA), poly-(epsilon-caprolactone) (PCL) and preferably polylactic acid (PLA).
Examples of additional polymers that may be used in embodiments of the invention include polymers derived from a combination of an aliphatic component possessing two carboxylic acid groups with an aliphatic component possessing two hydroxyl groups, and are polyesters derived from aliphatic diols and from aliphatic dicarboxylic acids, such as polybutylene succinate (PBS), polyethylene succinate (PES), polybutylene adipate (PBA), polyethylene adipate (PEA), polytetramethy-lene adipate/terephthalate (PTMAT).
Useful aliphatic polyesters include those derived from semicrystalline polylactic acid. Poly(lactic acid) or polylactide (PLA) has lactic acid as its principle degradation product, which is commonly found in nature, is non-toxic and is widely used in the food, pharmaceutical and medical industries. The polymer may be prepared by ring-opening polymerization of the lactic acid dimer, lactide. Lactic acid is optically active and the dimer appears in four different forms: L,L-lactide, D,D-lactide, D,L-lactide (meso lactide) and a racemic mixture of L,L- and D,D-. By polymerizing these lactides as pure compounds or as blends, poly(lactide) polymers may be obtained having different stereochemistries and different physical properties, including crystallinity. The L,L- or D,D-lactide yields semicrystalline poly(lactide), while the poly(lactide) derived from the D,L-lactide is amorphous.
Generally, polylactic acid based polymers are prepared from dextrose, a source of sugar, derived from field corn. In North America corn is used since it is the most economical source of plant starch for ultimate conversion to sugar. However, it should be recognized that dextrose can be derived from sources other than corn. Sugar is converted to lactic acid or a lactic acid derivative via fermentation through the use of microorganisms. Lactic acid may then be polymerized to form PLA. In addition to corn, other agriculturally-based sugar sources may be used including rice, sugar beets, sugar cane, wheat, cellulosic materials, such as xylose recovered from wood pulping, and the like.
The polylactide preferably has a high enantiomeric ratio to maximize the intrinsic crystallinity of the polymer. The degree of crystallinity of a poly(lactic acid) is based on the regularity of the polymer backbone and the ability to crystallize with other polymer chains. If relatively small amounts of one enantiomer (such as D-) is copolymerized with the opposite enantiomer (such as L-) the polymer chain becomes irregularly shaped, and becomes less crystalline. For these reasons, when crystallinity is favored, it is desirable to have a poly(lactic acid) that is at least 85% of one isomer, at least 90% of one isomer, or at least 95% of one isomer in order to maximize the crystallinity.
In some embodiments, an approximately equimolar blend of D-polylactide and L-polylactide is also useful. In certain embodiments, this blend forms a unique crystal structure having a higher melting point than does either the D-poly(lactide) and L-(polylactide) alone, and has improved thermal stability.
Copolymers, including block and random copolymers, of poly(lactic acid) with other aliphatic polyesters may also be used. Useful co-monomers include glycolide, beta-propiolactone, tetramethylglycolide, beta-butyrolactone, gamma-butyrolactone, pivalolactone, 2-hydroxybutyric acid, alpha-hydroxyisobutyric acid, alpha-hydroxyvaleric acid, alpha-hydroxyisovaleric acid, alpha-hydroxycaproic acid, alpha-hydroxyethylbutyric acid, alpha-hydroxyisocaproic acid, alpha-hydroxy-beta-methylvaleric acid, alpha-hydroxyoctanoic acid, alpha-hydroxydecanoic acid, alpha-hydroxymyristic acid, and alpha-hydroxystearic acid.
Blends of poly(lactic acid) and one or more other aliphatic polyesters, or one or more other polymers may also be used. Examples of useful blends include poly(lactic acid) and poly(vinyl alcohol), polyethylene glycol/polysuccinate, polyethylene oxide, polycaprolactone and polyglycolide.
In certain preferred embodiments, the aliphatic polyester component comprises a PLA based resin. A wide variety of different PLA resins may be used to prepare nonwoven fabrics in accordance with embodiments of the invention. The PLA resin should have proper molecular properties to be spun in spunbond processes. Examples of suitable include PLA resins are supplied from NatureWorks LLC, of Minnetonka, Minn. 55345 such as, grade 6752D, 6100D, and 6202D, which are believed to be produced as generally following the teaching of U.S. Pat. Nos. 5,525,706 and 6,807,973 both to Gruber et al. Other examples of suitable PLA resins may include L130, L175, and LX175, all from Corbion of Arkelsedijk 46, 4206 A C Gorinchem, the Netherlands.
In some embodiments, the inventive nonwoven fabrics may comprise bio-based polymer components of biodegradable products that are derived from an aliphatic component possessing one carboxylic acid group (or a polyester forming derivative thereof, such as an ester group) and one hydroxyl group (or a polyester forming derivative thereof, such as an ether group) or may be derived from a combination of an aliphatic component possessing two carboxylic acid groups (or a polyester forming derivative thereof, such as an ester group) with an aliphatic component possessing two hydroxyl groups (or a polyester forming derivative thereof, such as an ether group).
Additional nonlimiting examples of bio-based polymers include polymers directly produced from organisms, such as polyhydroxyalkanoates (e.g., poly(beta-hydroxyalkanoate), poly(3-hydroxybutyrate-co-3-hydroxyvalerate, NODAX™), and bacterial cellulose; polymers extracted from plants and biomass, such as polysaccharides and derivatives thereof (e.g., gums, cellulose, cellulose esters, chitin, chitosan, starch, chemically modified starch), proteins (e.g., zein, whey, gluten, collagen), lipids, lignins, and natural rubber; and current polymers derived from naturally sourced monomers and derivatives, such as bio-polyethylene, bio-polypropylene, polytrimethylene terephthalate, polylactic acid, NYLON 11, alkyd resins, succinic acid-based polyesters, and bio-polyethylene terephthalate.
In some embodiments, the bio-based polymer may comprise bio-based polyethylene, bio-based polypropylene, and bio-based polyesters, such as bio-based PET, that are derived from a biological source. For example, bio-based polyethylene can be prepared from sugars that are fermented to produce ethanol, which in turn is dehydrated to provide ethylene. An example of a suitable sugar cane derived polyethylene is available from Braskem S.A. under the product name PE SHA7260.
in some embodiments, the fibers may include one or more additional additives that are blended with the polymer(s) during the melt extrusion phase. Examples of suitable additives include one or more of colorants, such as pigments (e.g., TiO2), UV stabilizers, hydrophobic agents, hydrophilic agents, antistatic agent, elastomers, compatibilizers, antioxidants, anti-block agent, slip agents, surfactants, optical brighteners, flame retardants, antimicrobials, such as copper oxide and zinc oxide and the like.
In some embodiments, it may also be useful to optionally treat the nonwoven fabric with finishes containing additives or other chemicals, such as antimicrobial agents, flame retardant agents, hydrophobic agents, hydrophilic agents, catalysts, lubricants, softeners, light stabilizers, antioxidants, colorants such as dyes and/or pigments, antistatic agents, fillers, odor control agents, perfumes and fragrances, and the like, and combinations thereof. Other optional components may be included in the compositions described herein.
In accordance with certain embodiments, for example, the nonwoven fabric may have a basis weight from about 5 grams per square meter (gsm) to about 800 gsm.
In particular preferred embodiments, the nonwoven fabric may have basis weights ranging from about 200 to 800 gsm, such as 250 to 750 gsm, 300 to 700 gsm, 350 to 650 gsm, and 400 to 600 gsm.
For example, in certain embodiments, the nonwoven fabric comprises a meltblown fabric having a basis weight of at least 200 gsm, at least 210 gsm, at least 220 gsm, at least 230 gsm, at least 240 gsm, at least 250 gsm, at least 260 gsm, at least 270 gsm, at least 280 gsm, at least 290 gsm, at least 300 gsm, at least 310 gsm, at least 320 gsm, at least 330 gsm, at least 340 gsm, at least 350 gsm, at least 360 gsm, at least 370 gsm, at least 380 gsm, at least 390 gsm, at least 400 gsm, at least 410 gsm, at least 420 gsm, at least 430 gsm, at least 440 gsm, at least 450 gsm, at least 460 gsm, at least 470 gsm, at least 480 gsm, at least 490 gsm, at least 500 gsm, at least 510 gsm, at least 520 gsm, at least 530 gsm, at least 540 gsm, at least 550 gsm, at least 560 gsm, at least 570 gsm, at least 580 gsm, at least 590 gsm, at least 600 gsm, at least 610 gsm, at least 620 gsm, at least 630 gsm, at least 640 gsm, at least 650 gsm, at least 660 gsm, at least 670 gsm, at least 680 gsm, at least 690 gsm, at least 700 gsm, at least 710 gsm, at least 720 gsm, at least 730 gsm, at least 740 gsm, at least 750 gsm, at least 760 gsm, at least 770 gsm, at least 780 gsm, and at least 790 gsm.
In certain embodiments, the nonwoven fabric comprises a meltblown fabric having a basis weight of less than 800 gsm, less than 790 gsm, less than 780 gsm, less than 770 gsm, less than 760 gsm, less than 750 gsm, less than 740 gsm, less than 730 gsm, less than 720 gsm, less than 710 gsm, 700 gsm, less than 690 gsm, less than 680 gsm, less than 670 gsm, less than 660 gsm, less than 650 gsm, less than 640 gsm, less than 630 gsm, less than 620 gsm, less than 610 gsm, 600 gsm, less than 590 gsm, less than 580 gsm, less than 570 gsm, less than 560 gsm, less than 550 gsm, less than 540 gsm, less than 530 gsm, less than 520 gsm, less than 510 gsm, 500 gsm, less than 490 gsm, less than 480 gsm, less than 470 gsm, less than 460 gsm, less than 450 gsm, less than 440 gsm, less than 430 gsm, less than 420 gsm, less than 410 gsm, 400 gsm, less than 390 gsm, less than 380 gsm, less than 370 gsm, less than 360 gsm, less than 350 gsm, less than 340 gsm, less than 330 gsm, less than 320 gsm, less than 310 gsm, 300 gsm, less than 290 gsm, less than 280 gsm, less than 270 gsm, less than 260 gsm, less than 250 gsm, less than 240 gsm, less than 230 gsm, less than 220 gsm, and less than 210 gsm.
It should also be recognized that embodiments of the invention encompasses ranges of the above mentioned basis weights, such as from 200 to 800 gsm, 210 to 790 gsm, 220 to 780 gsm, 300 to 600 gsm, 350 to 550 gsm, 400 to 600 gsm, etc.
In other embodiments, for instance, the fabric may have a basis weight from about 8 gsm to about 150 gsm. In certain embodiments, for example, the fabric may comprise a basis weight from about 10 gsm to about 70 gsm. In further embodiments, for instance, the fabric may have a basis weight from about 11 gsm to about 40 gsm. In one embodiment, the fabric may have a basis weight from about 15 gsm to about 25 gsm. As such, in certain embodiments, the fabric may have a basis weight from at least about any of the following: 5, 6, 7, 8, 9, 10, and 11 gsm and/or at most about 150, 100, 70, 60, 50, 40, and 30 gsm (e.g., about 9-60 gsm, about 11-40 gsm, etc.).
For meltblown fibers, the fibers may have a linear mass density from about 0.05 dtex to about 2.0 dtex. In certain embodiments, the fibers have a linear mass density from at least about any of the following: 0.06, 0.07, 0.08, 0.09, 0.1, 0.15, 0.20, 0.25, 0.30, 0.35, 0.40, 0.45, 0.50, 0.55, 0.60, 0.65, 0.70, 0.75, 0.80, 0.85, 0.90, 0.95, 1.0, 1, 1.1, 1.2, 1.3, 1.4, 1.5, 1.6, 1.7, 1.8, 1.9, and at least 1.95 dtex and/or at most about 2.0, 1.95, 1.9, 1.8, 1.7, 1.6, 1.5, 1.4, 1.3, 1.2, 1.1, 1.0, 0.95, 0.90, 0.85, 0.80, 0.75, 0.70, 0.65, 0.60, 0.55, 0.50, 0.45, 0.40, 0.35, 0.30, 0.25, 0.20, 0.15, 0.1, 0.09, 0.08, and 0.07 dtex (e.g., about 0.05-2.0 dtex, about 0.06-1.95 dtex, etc.).
According to certain embodiments in which the nonwoven fabric comprises a spunbond fabric, the fibers may have a linear mass density from about 0.05 dtex to about 12 dtex. In other embodiments, for instance, the fibers may have a dtex from about 1 dtex to about 10 dtex. In further embodiments, for example, the fibers may have a linear mass density from about 1.2 dtex to about 6 dtex. As such, in certain embodiments, the fibers have a linear mass density from at least about any of the following: 0.6, 0.7, 0.8, 0.9, 1.0, 1, 1.1, 1.2, 1.3, 1.4, 1.5, and 1.6 dtex and/or at most about 2.5, 2.4, 2.3, 2.2, 2.1, 2.0, 1.9, 1.8, and 1.7 dtex (e.g., about 1-2.5 dtex, about 1.1-1.8 dtex, etc.).
The fibers comprising the nonwoven fabric may have diameters ranging from less than 1 micron up to about 60 microns, depending on the type of fiber.
For example, meltblown fibers in accordance with certain embodiments of the invention may have average fiber diameters ranging from 0.5 to 14 microns (μm). In certain embodiments, meltblown nonwoven fabrics comprise meltblown fibers having average fiber diameters ranging from 1 to 10 μm, such as from about 2 to 8, from about 3 to 6 μm, and from about 3.5 to 4.5 μm.
In certain embodiments, fibers may have a mean fiber diameter ranging from about 3.5 to 4.5 microns with a standard deviation of less than 2 microns. For example, meltblown fibers of the inventive nonwoven fabric may exhibit an average mean fiber diameter of 4.0 μm with an average standard deviation of 1.4.
As discussed previously, nonwoven fabrics in accordance with embodiments of the present invention may exhibit an increase in thickness that is greater in comparison to a similarly prepared nonwoven fabric that does not include the high loft additive. In some embodiments, the nonwoven fabric may exhibit an increase in thickness (caliper or loft) that is from 50% to 200% greater than the thickness of a similarly prepared nonwoven fabric that does not include the high loft additive.
In certain embodiments, nonwoven fabrics in accordance with embodiment the invention exhibit an increase in thickness (caliper) ranging from 10 to 1,000%, and in particular, from about 20 to 500%, and more particularly, from 100 to 250% in comparison to a similar nonwoven fabric in which the similar nonwoven comprises fibers that do not include the high loft additive.
The nonwoven fabric may exhibit an increase in thickness that is at least 10%, at least 20%, at least 30%, at least 40%, at least 50%, at least 60%, at least 70%, at least 80%, at least 90%, at least 100%, at least 110%, at least 120%, at least 130%, at least 140%, at least 150%, at least 160%, at least 170%, at least 180%, at least 190%, and at least 200% in comparison to a similarly prepared nonwoven fabric that does not include the high loft additive.
In certain embodiments, the nonwoven fabric may exhibit an increase in thickness that is less than about 210%, less than about 200%, less than about 190%, less than about 180%, less than about 170%, less than about 160%, less than about 150%, less than about 140%, less than about 130%, less than about 120%, less than about 110%, less than about 100%, less than about 90%, less than about 80%, less than about 70%, less than about 60%, less than about 50%, less than about 40%, less than about 30%, less than about 30%, and less than about 15% in comparison to a similarly prepared nonwoven fabric that does not include the high loft additive.
It should also be recognized that embodiments of the invention encompasses ranges of the above mentioned increases in thickness, such as from 10 to 220%, 20 to 200%, 30 to 190%, 40 to 80%, 50 to 150%, and 80 to 140% in comparison to a similarly prepared nonwoven fabric that does not include the high loft additive.
Fabrics in accordance with certain embodiments of the invention may also provide improved sound attenuation.
In certain embodiments, nonwoven fabrics in accordance with the invention exhibit a percent increase in Average Absorption Coefficient (AAC) from 20 to 250% in comparison to a similarly prepared or identical nonwoven fabric that does not include the high loft additive.
For example, the inventive nonwoven fabrics may exhibit an increase in the Average Absorption Coefficient (AAC) of at least 20%, at least 25%, at least 30%, at least 35%, at least 40%, at least 45%, at least 50%, at least 55%, at least 60%, at least 65%, at least 70%, at least 75%, at least 80%, at least 85%, at least 90%, at least 95%, at least 100%, at least 105%, at least 110%, at least 115%, at least 120%, at least 125%, at least 130%, at least 135%, at least 140%, at least 145%, at least 150%, at least 155%, at least 160%, at least 165%, at least 170%, at least 175%, at least 180%, at least 185%, at least 190%, at least 195%, at least 200%, at least 205%, at least 210%, at least 215%, at least 220%, at least 225%, at least 230%, at least 235%, at least 240%, and at least 245%, in comparison to a similarly prepared nonwoven fabric that does not include the high loft additive.
In certain embodiments, the inventive nonwoven fabrics may exhibit an increase in the Average Absorption Coefficient (AAC) that is less than about 250%, less than about 245%, less than about 240%, less than about 235%, less than about 230%, less than about 225%, less than about 220%, less than about 215%, less than about 210%, less than about 205%, less than about 200%, less than about 195%, less than about 190%, less than about 185%, less than about 180%, less than about 175%, less than about 170%, less than about 165%, less than about 160%, less than about 155%, less than about 150%, less than about 145%, less than about 140%, less than about 135%, less than about 130%, less than about 125%, less than about 120%, less than about 115%, less than about 110%, less than about 105%, less than about 100%, less than about 95%, less than about 90%, less than about 85%, less than about 80%, less than about 75%, less than about 70%, less than about 65%, less than about 60%, less than about 55%, less than about 50%, less than about 45%, less than about 40%, less than about 35%, less than about 30%, and less than about 25%, in comparison to a similarly prepared nonwoven fabric that does not include the high loft additive.
It should also be recognized that embodiments of the invention encompasses ranges of the above mentioned increases in AAC, such as from 10 to 220%, 20 to 200%, 30 to 190%, 40 to 80%, 45 to 150%, 80 to 140%, and 45 to 55% in comparison to a similarly prepared nonwoven fabric that does not include the high loft additive.
In addition, nonwoven fabrics in accordance with certain embodiments of the invention, exhibit improvements with respect to thermal conductivity and thermal resistance. More specifically, certain embodiments of the inventive nonwoven fabric may exhibit an increase in thermal resistance and a decrease in thermal conductivity in comparison to a similarly prepared nonwoven fabric that does not include the high loft additive. As a consequence, nonwoven fabrics in accordance with embodiments of the invention may be particularly suited for applications where thermal isolation or thermal insulative properties are desirable.
In certain embodiments, the inventive nonwoven fabrics may exhibit a thermal resistance ranging from about 0.100 to 0.500 K·m2/Watt, and in particular, from about 0.125 to 0.300 K·m2/Watt, and more particularly, from about 0.150 to 0.225 K·m2/Watt. For example, the thermal resistance may range from 0.160 to 0.200 K·m2/Watt.
In certain embodiments, nonwoven fabrics in accordance with the invention exhibit a percent increase in thermal resistance from 25 to 500% in comparison to a similarly prepared or identical nonwoven fabric that does not include the high loft additive.
For example, the inventive nonwoven fabrics may exhibit an increase in thermal resistance of at least 25%, at least 30%, at least 35%, at least 40%, at least 45%, at least 50%, at least 55%, at least 60%, at least 65%, at least 70%, at least 75%, at least 80%, at least 85%, at least 90%, at least 95%, at least 100%, at least 105%, at least 110%, at least 115%, at least 120%, at least 125%, at least 130%, at least 135%, at least 140%, at least 145%, at least 150%, at least 155%, at least 160%, at least 165%, at least 170%, at least 175%, at least 180%, at least 185%, at least 190%, at least 195%, at least 200%, at least 205%, at least 210%, at least 215%, at least 220%, at least 225%, at least 230%, at least 235%, at least 240%, at least 245%, at least 250%, at least 255%, at least 260%, at least 265%, at least 270%, at least 275%, at least 280%, at least 285%, at least 290%, at least 295%, at least 300%, at least 305%, at least 310%, at least 315%, at least 320%, at least 325%, at least 330%, at least 335%, at least 340%, at least 345%, at least 350%, at least 355%, at least 360%, at least 365%, at least 370%, at least 375%, at least 380%, at least 385%, at least 390%, at least 395%, at least 400%, at least 405%, at least 410%, at least 415%, at least 420%, at least 425%, at least 430%, at least 435%, at least 440%, at least 445%, at least 450%, at least 455%, at least 460%, at least 465%, at least 470%, 475%, at least 480%, at least 485%, at least 490%, at least 495%, and at least 500%, in comparison to a similarly prepared nonwoven fabric that does not include the high loft additive.
In certain embodiments, the inventive nonwoven fabrics may exhibit an increase in thermal resistance that is less than about 500%, less than about 495%, less than about 490%, less than about 485%, less than about 480%, less than about 475%, less than about 470%, less than about 465%, less than about 460%, less than about 455%, less than about 450%, less than about 445%, less than about 440%, less than about 435%, less than about 430%, less than about 425%, less than about 420%, less than about 415%, less than about 410%, less than about 405%, less than about 400%, less than about 395%, less than about 390%, less than about 385%, less than about 380%, less than about 375%, less than about 370%, less than about 365%, less than about 360%, less than about 355%, less than about 350%, less than about 345%, less than about 340%, less than about 335%, less than about 330%, less than about 325%, less than about 320%, less than about 315%, less than about 310%, less than about 305%, less than about 300%, less than about 295%, less than about 290%, less than about 285%, less than about 280%, less than about 275%, less than about 270%, less than about 265%, less than about 260%, less than about 255%, less than about 250%, less than about 245%, less than about 240%, less than about 235%, less than about 230%, less than about 225%, less than about 220%, less than about 215%, less than about 210%, less than about 205%, less than about 200%, less than about 195%, less than about 190%, less than about 185%, less than about 180%, less than about 175%, less than about 170%, less than about 165%, less than about 160%, less than about 155%, less than about 150%, less than about 145%, less than about 140%, less than about 135%, less than about 130%, less than about 125%, less than about 120%, less than about 115%, less than about 110%, less than about 105%, less than about 100%, less than about 95%, less than about 90%, less than about 85%, less than about 80%, less than about 75%, less than about 70%, less than about 65%, less than about 60%, less than about 55%, less than about 50%, less than about 45%, less than about 40%, less than about 35%, less than about 30%, and less than about 25%, in comparison to a similarly prepared nonwoven fabric that does not include the high loft additive.
It should also be recognized that embodiments of the invention encompasses ranges of the above mentioned increases in thermal resistance, such as from 25 to 500%, 75 to 400%, 100 to 300%, 125 to 250%, 150 to 225%, 160 to 200%, 170 to 190%, and et cetera, in comparison to a similarly prepared nonwoven fabric that does not include the high loft additive.
In certain embodiments, the inventive nonwoven fabrics may exhibit a thermal conductivity ranging from about 0.020 to 0.040 to 0.500 Watts/m·K, and in particular, from about 0.025 to 0.0380 Watts/m·K, and more particularly, from about 0.0350 to 0.0370 Watts/m·K. For example, the thermal conductivity may range from 0.0355 to 0.0365 Watts/m·K.
In certain embodiments, nonwoven fabrics in accordance with the invention exhibit a percent decrease in thermal conductivity from 10 to 50% in comparison to a similarly prepared or identical nonwoven fabric that does not include the high loft additive.
For example, the inventive nonwoven fabrics may exhibit a decrease in thermal conductivity of at least 10%, at least 11%, at least 12%, at least 13%, at least 14%, at least 15%, at least 16%, at least 17%, at least 18%, at least 19%, at least 20%, at least 21%, at least 22%, at least 23%, at least 24%, at least 25%, at least 26%, at least 27%, at least 28%, at least 29%, at least 30%, at least 31%, at least 32%, at least 33%, at least 35%, at least 36%, at least 37%, at least 38%, at least 39%, at least 40%, at least 41%, at least 42%, at least 43%, at least 44%, at least 45%, at least 46%, at least 47%, at least 48%, at least 49%, and at least 50%, in comparison to a similarly prepared nonwoven fabric that does not include the high loft additive.
In certain embodiments, the inventive nonwoven fabrics may exhibit a decrease in thermal conductivity that is less than about 50%, less than about 49%, less than about 48%, less than about 47%, less than about 46%, less than about 45%, less than about 44%, less than about 43%, less than about 42%, less than about 41%, less than about 40%, less than about 39%, less than about 38%, less than about 37%, less than about 36%, less than about 35%, less than about 34%, less than about 33%, less than about 32%, less than about 31%, less than about 30%, less than about 29%, less than about 28%, less than about 27%, less than about 26%, less than about 25%, less than about 24%, less than about 23%, less than about 22%, less than about 21%, less than about 20%, less than about 19%, less than about 18%, less than about 17%, less than about 16%, less than about 15%, less than about 14%, less than about 13%, less than about 12%, less than about 11%, and less than about 10%, in comparison to a similarly prepared nonwoven fabric that does not include the high loft additive.
Certain aspects of the invention provide systems and methods for preparing a nonwoven fabric in accordance with embodiments described previously discussed.
With reference to
In certain embodiments, a source of a high loft additive 108 is in fluid communication with either the hopper 102 or the extruder 106. The high loft additive may be preblended with the polymer or may be metered into the hopper or extruder.
In certain embodiments, the first polymer source may provide a stream of a molten or semi-molten polymer resin. Following extrusion, the extruded polymer stream containing the blend of the polymer hand high loft additive are introduced into the meltblown spin beam 104 at which point a plurality of streams are introduced into a die head (not shown) of a meltblown spin beam. The die head includes a plurality of fluid orifices and one or more streams of air for drawing and attenuating the polymer streams as they exit the die head to produce a stream of meltblown fibers. The spin beam 104 produces a stream of meltblown fibers 107 that are deposited on the collection surface 110 to produce a web of filaments. At this stage, the filaments may comprise a web 112 of filaments that are unbonded or slightly bonded to each other.
In certain embodiments, an optional bonding unit 116 is disposed downstream of the collection surface 110 and is configured and arranged to thermally bond fibers to each other to form a coherent web. During thermal bonding the web 112 of fibers, the fibers are heated to a temperature that is sufficient to soften at least one polymer component comprising fibers of web 112 to produce a bonded nonwoven fabric 124. In certain embodiments, the bonded nonwoven fabric 124 moves to a winder 118, where the fabric is then wound onto rolls.
In certain embodiments, the bonding unit comprises an air through bonder in which the fibers are exposed to one or more streams of heated gas, such as air. In other embodiments, the bonding unit may comprise a calender bonding unit comprising a pair of cooperating heated rolls in which at least one of the rolls includes a plurality of raised bonding points on a surface thereof. The bonding points can be used to impart a bonding pattern on at least one surface of the nonwoven fabric. In some embodiments, the calender comprises a pair of cooperating rolls in which a first roll comprises an engraved patterned roll having a plurality of bonding points extending from a surface thereof, and the second roll comprises smooth or anvil surface. During bonding, the web of meltblown fibers passes between the pair cooperating rolls, which are heated to a temperature that is sufficient to soften at least one polymer component comprising filaments of web such that the softened polymer component fuses and bonds to adjacent filaments within the web to produce a bonded nonwoven fabric.
In some embodiments, an optional pair of cooperating rolls 120 (also referred to herein as a “press roll”) stabilize the web of fibers by compressing the web before delivery to the winder 118 or the bonding unit 116 for bonding. The use of a press roll may be desirable in spunbond manufacturing processes. In some embodiments, for example, the press roll, when present, may include a ceramic coating deposited on a surface thereof. In certain embodiments, for instance, one roll of the pair of cooperating rolls 120 may be positioned above the collection surface 110, and a second roll of the pair of cooperating rolls 120 may be positioned below the collection surface 110. In some embodiments, the system may also include a hot air knife (not shown) that exposes the web 112 to a stream of heated gas, such as air, to lightly bond and stabilize the web.
In some embodiments, the system 100a may further comprise a vacuum source 128 disposed below collection surface 110. Vacuum source 128 provides a vacuum that helps draw and pull the fibers 107 onto collection surface 110.
With reference to
System 100b includes a first polymer source (i.e. hopper) 130a that is in fluid communication with the meltblown spin beam 134 via the extruder 136a. A second polymer source (i.e. hopper) 130b is also in fluid communication with the meltblown spin beam 134 via extruder 136b. In the preparation of multicomponent fabrics, first polymer source may provide a stream of a first polymer resin, and the second polymer source may provide a stream of a second polymer resin. In melt spinning applications, the polymer streams are typically in a molten or semi-molten state. The first polymer resin and the second polymer resin may be different polymers, or may be the same polymers depending on the desired application and desired properties of the nonwoven fabric. For example, the first polymer resin may comprise a first polypropylene polymer and the second polymer resin may comprise a second polymer resin.
A source of a high loft additive 108 is in fluid communication at least one of the extruders 136a, 136b, or with at least one of the hoppers 130a, 130b. The high loft additive may be preblended with the polymer or may be metered into the hopper or extruder. In
Following extrusion, the extruded polymer streams are introduced into the meltblown spin beam 134 at which point the plurality of polymer streams are introduced into a die head (not shown) of a meltblown spin beam. The die head includes a plurality of fluid orifices and one or more streams of gas, such as air, for drawing and attenuating the polymer streams as they exit the die head to produce a stream of meltblown fibers.
The spin beam 134 produces a plurality of multicomponent meltblown fibers 138 that are deposited on the collection surface 110 to produce a web 140 of meltblown fibers. At this stage, the meltblown web may comprise a web 140 of multicomponents fibers that are unbonded or slightly bonded to each other.
In certain embodiments, an optional bonding unit 116 is disposed downstream of the collection surface 110 and is configured and arranged to thermally bond filaments to each other to form a coherent web. During thermal bonding the web 140 of fibers, the fibers are heated to a temperature that is sufficient to soften at least one polymer component comprising fibers of web 140 to produce a bonded nonwoven fabric 124. In certain embodiments, the bonded or non-bonded nonwoven fabric moves to a winder 118, where the fabric is then wound onto rolls.
In certain embodiments, the bonding unit comprises an air through bonder in which the fibers are exposed to one or more streams of heated gas, such as air.
In other embodiments, the bonding unit may comprise a calender bonding unit comprising a pair of cooperating heated rolls in which at least one of the rolls includes a plurality of raised bonding points on a surface thereof. The bonding points can be used to impart a bonding pattern on at least one surface of the nonwoven fabric. In some embodiments, the calender comprises a pair of cooperating rolls in which a first roll comprises an engraved patterned roll having a plurality of bonding points extending from a surface thereof, and the second roll comprises smooth or anvil surface. During bonding, the web of meltblown fibers passes between the pair cooperating rolls, which are heated to a temperature that is sufficient to soften at least one polymer component comprising filaments of web such that the softened polymer component fuses and bonds to adjacent filaments within the web to produce a bonded nonwoven fabric.
As in the previously discussed embodiment, system 100b may also include an optional pair of cooperating rolls 120, optional hot air knife, and vacuum source 128.
Embodiments of the invention, may also include multilayered nonwoven fabrics having 2 to 10 layers, such as 2 to 5, and in particular, 2 to 3 layers.
Various layers of the nonwoven fabric may include one or more spunbond layers, one or more carded layers, one or more air laid layers, one or more meltblown layers, and the like.
In certain embodiments, the bonded nonwoven fabric may include a layer comprising monocomponent filaments and a second layer comprising multicomponent filaments, such as bicomponent filaments.
In embodiments in which the bonded nonwoven fabric includes multiple layers, the system may include additional fiber forming devices as desired. For example, systems in accordance with embodiments of the invention may include one or more meltblown beams, one or more devices for preparing carded fabric layers, one or more devices for preparing airlaid fabric layers, and the like. Such additional devices may be the same manufacturing line with the other fiber forming devices to provide a continuous system. Alternatively, one or more additional layers may be provided from a supply roll onto which a previously prepared nonwoven fabric was wound.
In certain embodiments, the nonwoven fabric may include at least one spunbond layer comprising filaments having no crimping or low crimping, and a least one layer comprising crimped filaments.
In accordance with certain embodiments, for instance, bonding the web to form the bonded nonwoven fabric comprises thermal point bonding the web with heat and pressure via a calender having a pair of cooperating rolls including a patterned roll. The patterned roll imparts a three-dimensional geometric bonding pattern onto the nonwoven fabric.
With reference to
Structural layer may be rigid, semi-rigid or flexible. Examples of materials that may be suitable as structural layer include, fiber boards including medium density fiberboard (MDF), plywood, fibrous cement boards, and the like, wood based boards and sheets, carbon fiber sheets including resin impregnated fiber carbon sheets, such as prepregs, film structures, foamed structures, textile sheets including woven and nonwoven, metal based sheets, such as sheet metal, expanded metal sheets, perforated metal sheets, and corrugated metal sheets, and the like. In particularly preferred embodiments, composite sheet comprises the inventive nonwoven fabric comprising a polymeric blend of a polymer and the high loft additive, and one or more additional nonwoven layers, such as one or more meltblown nonwoven fabrics, one or more spunbond fabrics, one or more carded fabrics, one or more air laid fabrics, one or more resin bonded fabrics, one or more spunlace fabric layers, or the like, and combinations thereof.
In some embodiments, both the first nonwoven fabric and the second nonwoven fabric may each comprise a spunbond nonwoven fabric.
In certain embodiments, the inventive nonwoven fabric may be combined with one or more additional nonwoven layers to prepare a composite or laminate material.
Examples of such composites/laminates may include a spunbond composite, such as a spunbond-meltblown (SM) composite, a spunbond-meltblown-spunbond (SMS) composite, or a spunbond-meltblown-meltblown-spunbond (SMMS) composite), a spunbond-spunbond-meltblown-meltblown-spunbond (SSMMS), or a spunbond-spunbond-meltblown-spunbond (SSMS) composite. In some embodiments, composites may be prepared comprising a layer of the bonded nonwoven fabric and one or more film layers. It should be recognized other configurations are also in the scope of the invention.
For example,
Finally,
In these multilayer structures, the basis weight of the spunbond nonwoven fabric layers may range from as low as 5 g/m2 and up to 150 g/m2. In such multilayered laminates, both the meltblown and spunbond fibers could have a similar polymer on the surface of the fibers to help facilitate optimum bonding. In some embodiments in which the inventive meltblown layer is a part of a multilayer structure (e.g., SM, SMS, and SMMS), the amount of the meltblown in the structure may range from about 10 to 90%, and in particular, from about 40 to 75% of the structure as a percentage of the structure as a whole.
Multilayer structures in accordance with embodiments can be prepared in a variety of manners including continuous in-line processes where each layer is prepared in successive order on the same line, or depositing a meltblown layer on a previously formed spunbond layer. The layers of the multilayer structure can be bonded together to form a multilayer composite sheet material using thermal bonding, mechanical bonding, adhesive bonding, hydroentangling, or combinations of these.
Multilayer structures in accordance with embodiments can be prepared in a variety of manners including continuous in-line processes where each layer is prepared in successive order on the same line, or depositing a second nonwoven layer on a previously formed spunbond layer. The layers of the multilayer structure can be thermally bonded together to form a multilayer composite sheet material to provide a composite sheet material having the bonding patterns described herein. In addition, composite sheet materials in accordance with certain embodiments of the invention may also be subjected to other bonding techniques, such as thermal bonding via an air through dry, mechanical bonding, adhesive bonding, hydroentangling, or combinations of these. In certain embodiments, the layers may be thermally point bonded to each other by passing the multilayer structure through a bonding unit comprising an air through bonder, such as an oven, in the fibers are exposed to a heated stream of gas, such as air.
In some embodiments, the layers may be thermally point bonded to each other by passing the multilayer structure through a bonding unit comprising a pair of calender rolls in which the patterned roll of the calender has an engraved surface comprising a bonding pattern thereon.
As previously noted, fabrics prepared in accordance with embodiments of the invention may be used in wide variety of articles and applications. For instance, embodiments of the invention may be used for personal care applications, for example products for babycare (diapers, wipes), for femcare (pads, sanitary towels, tampons), for adult care (incontinence products), or for cosmetic applications (pads), agricultural applications, for example root wraps, seed bags, crop covers, industrial applications, for example work wear coveralls, airline pillows, automobile trunk liners, sound proofing, and household products, for example mattress coil covers and furniture scratch pads, and appliances, such as refrigerators.
In one particular application, nonwoven fabrics in accordance with certain embodiments of the invention are particularly suited in applications where sound attenuation is desirable. Such application may include commercial and residential construction, sound attenuation in automotive vehicles, sound attenuation in boats and ships, and the like.
For example, nonwoven fabrics in accordance with the invention may be used as various sound dampening articles in the manufacture of automotive vehicles. The nonwoven fabrics may be used in the engine compartment, such as in the hood, sidewalls, and in the firewall. In the interior, the nonwoven fabrics may be used in the headliner, floor underlayment, visors, in the dash, in the trunk space, and the like.
In construction applications, the inventive nonwoven fabrics may be used as floor and roof underlayment, insulative panels, inner wall insulative material and the like.
Embodiments of the invention are also directed to composite articles comprising the inventive nonwoven fabrics including in the use and manufacture of sound absorbing articles.
Embodiments of the invention are particularly useful for applications where heat insulative properties are desirable. Such applications include commercial, industrial, and residential applications.
Examples of commercial applications include use in walls, foundations, roofs and decking materials, air distribution, ceilings, pipes, tanks, vessels, and the like. Industrial applications may include in appliances, pipes, ovens, boilers, and furnaces, commercial and consumer vehicles, including in engine and passenger compartments, computer and server applications, and the like.
In residential applications, the inventive nonwovens can be used as a surface application or within the building structure. Such potential applications include in attic, crawl space, basements, and garage spaces, within walls, as a floor underlayment, air distribution systems, as a wrap for thermal isolation of water and similar lines, and the like.
The following examples are provided for illustrating one or more embodiments of the present invention and should not be construed as limiting the invention.
Meltblown nonwoven fabrics in the following examples were prepared with a meltblown line produced by Hills. Unless otherwise indicated all percentages are weight percentages. The materials and test methods used in the examples are identified below.
Basis weight was measured in accordance with NWSP 130.1.
Caliper was measure in accordance with NWSP 120.6.
Air Permeability was measured in accordance with ASTM 90.3.
Average Absorption Coefficient was measured in accordance ASTM E1050-12 by Riverbank Acoustical Laboratories.
Thermal Resistance and Thermal Conductivity was determined with the Standard Test Method for Steady-State Heat Flux Measurements and Thermal Transmission Properties by Means of a Guarded-Hot Plate Apparatus in accordance with ASTM C177.
“PP-1” refers to a homopolymer polypropylene having an MFR of 1250 g/10 min and a density of 0.905 g/cm3 available from Braskem under the product number H155.
“EBS-1” refers to a polypropylene masterbatch comprising 25 weight percent of ethylene bis stearamide (EBS), based on the total weight of the masterbatch. The polypropylene carrier resin was a metallocene catalyzed polypropylene obtained from Lyondellbasell under the tradename METOCENE™. The polypropylene carrier had an MFR of 500 g/10 minutes and a density of 0.93 g/cm3. The masterbatch composition had an MFR of 850 g/10 minutes and a density of 0.95 g/cm3 with a heat stability of 260° C. The EBS-1 masterbatch was obtained from Sandridge Color Corporation under the product code No. 22188.
“EBS-2” refers to an ethylene bis stearamide (EBS) available from CRODA Polymer Additives under the product name CRODAMIDE™ EBS.
In Comparative Example 1, a meltblown nonwoven fabric comprising PP-1 was prepared. The meltblown fabric had a basis weight of 640 gsm and did not include any EBS. The meltblown fibers were deposited onto a moving collection surface and were not subject to any further bonding.
In Comparative Example 2, a meltblown nonwoven fabric comprising PP-1 was prepared. The meltblown fabric had a basis weight of 640 gsm and did not include any EBS. The meltblown fibers were deposited onto a moving collection surface and not subject to any further bonding.
In Comparative Example 3, a meltblown nonwoven fabric comprising PP-1 was prepared. The meltblown fabric had a basis weight of 450 gsm and did not include any EBS. The meltblown fibers were deposited onto a moving collection surface and not subject to any further bonding.
Inventive Example 1 was identical to the nonwoven fabric of Comparative Example 1 with the exception that the fibers of the nonwoven fabric comprised a blend of PP-1 and masterbatch EBS-1. The amount of EBS-1 in the blend was 4 weight percent, based on the total weight of the blend. The overall amount of EBS in the blend was 1 weight percent based on the total weight of the blend. The meltblown nonwoven fabric of Example 1 had a basis weight of 640 gsm.
Inventive Example 2 was prepared in a similar manner to Comparative Example 1 and Inventive Example 1. The amount of masterbatch EBS-1 in the blend of Inventive Example 2 was 6 weight percent, based on the total weight of the blend. The overall amount of EBS in the blend was 1.5 weight percent based on the total weight of the blend. The meltblown nonwoven fabric of Inventive Example 2 had a basis weight of 451 gsm.
In Inventive Example 3, PP-1 was blended with EBS-2 and a meltblown nonwoven fabric was prepared in a similar manner as in Comparative Example 1. The amount of EBS-2 in the blend was 1.0 weight percent based on the total weight of the blend. The meltblown nonwoven fabric of Inventive Example 3 had a basis weight of 407.5 gsm.
In Inventive Example 4, PP-1 was blended with EBS-2 and a meltblown nonwoven fabric was prepared in a similar manner as in Comparative Example 1. The amount of masterbatch EBS-1 in the blend of Inventive Example 4 was 2 weight percent, based on the total weight of the blend. The overall amount of EBS in the blend was 0.5 weight percent based on the total weight of the blend. The meltblown nonwoven fabric of Inventive Example 4 had a basis weight of 450 gsm.
In Inventive Example 5, PP-1 was blended with EBS-2 and a meltblown nonwoven fabric was prepared in a similar manner as in Comparative Example 1. The amount of EBS-2 in the blend was 1.5 weight percent based on the total weight of the blend. The meltblown nonwoven fabric of Inventive Example 5 had a basis weight of 450 gsm.
The increase in thickness of the Inventive Examples 1-3 in comparison to Comparative Example 1 are summarized in Table 1, below.
From Table 1, it can be seen that the addition of the high loft additive significantly increases the caliper (thickness) of the inventive nonwoven fabrics in comparison to the control sample, which did not include the additive. In particular, the nonwoven fabrics of the inventive examples exhibited increases in thickness ranging from 40 to about 50% in comparison to the fabric of the control sample, which did not include the high loft additive.
In addition, when basis weights of the samples are taken into consideration, it can be seen that the improvements in thickness are even more pronounced. In particular, Inventive Example 2 exhibited an increase in thickness of more than 100% (104.3%) and Inventive Example 3 exhibited an increase in thickness of more than 130% (132.3) in comparison to the nonwoven fabric of Comparative Example 1, which did not include the high loft additive. Accordingly, the examples show that the inventive nonwoven fabrics having the high loft additive exhibited an increase in thickness from 35 to 150% in comparison to a similarly prepared fabric that did not include the high loft additive.
In addition to an increase in thickness, the inventive examples also demonstrated improved sound attenuation properties in comparison to the comparative example, which did not include the high loft additive. Samples of the nonwoven fabrics of Comparative Example 1 and Inventive Examples 1-3 were evaluated for average Absorption Coefficient over frequencies ranging from 80 Hz to 6,300 Hz. The results are summarized in Tables 2 and 3, which are provided below.
From Tables 2 and 3, it can be seen that the Inventive Nonwoven fabrics exhibited increases Average Absorption Coefficients over the frequency range of 80 to 6,300 Hz in comparison to Comparative Example 1. In Table 3, it can be seen that the inventive nonwoven fabrics exhibited increases in sound absorption, as evidenced by the Average Absorption Coefficient of the fabrics, that ranged between 45 and 55%. When considering differences in basis weight of the samples, the increase in the Average Absorption Coefficient (AAC) of the inventive examples in comparison to the comparative example, the inventive examples exhibited percent increases ranging from 45 to 150%.
In Table 4, the Average Absorption Coefficient for the inventive nonwoven fabrics was evaluated at mid-range frequencies (500 to 2,500 Hz) and at high range frequencies (2,500 to 6,300 Hz). As shown in Table 4, the inventive nonwoven fabrics exhibited a percent increase in AAC for mid-range frequencies ranging from 50 to 185% in comparison to the comparative nonwoven fabric, which did not include the high loft additive. In addition, the inventive nonwoven fabrics exhibited a percent increase in AAC for high range frequencies ranging from 40 to 45% in comparison to the comparative nonwoven fabric, which did not include the high loft additive.
In Table 5, below, the effects of the high loft additive on fiber diameters was evaluated.
From the foregoing results, it is evident that the inventive nonwoven fabrics exhibit increases in thickness and sound absorbance in comparison to the nonwoven fabrics, which did not include the high loft additive Such improvements make the inventive nonwoven fabric ideally suited for applications where sound attenuation is desirable.
The inventive nonwoven fabrics also exhibit improvements in heat transfer properties including thermal resistance and thermal conductivity.
As can be seen from Table 7, the inventive fabrics with the additive provide improvements in the increase in thermal resistance and decreases in thermal conductivity in comparison to an identically prepared fabric that did not include the additive.
This application claims priority from U.S. Provisional Application No. 63/449,352 filed Mar. 2, 2023, the contents of which are incorporated by reference in their entirety.
| Number | Date | Country | |
|---|---|---|---|
| 63449352 | Mar 2023 | US |
