KR20170026496A - Thermally stable meltblown web comprising multilayer fibers - Google Patents

Abstract

A thermostable meltblown fiber web comprising a plurality of the melt-blown multilayered fiber, in which at least the meltblown multi-layer fiber portion is at least one first layer comprising a first polymer to crystallize slowly, having more than about 200 ℃ T _m It includes, and a second layer at least one of a second polymer having a fast crystallization at least about 200 ℃ T _m respectively.

Description

[0001] THERMALLY STABLE MELTBLOWN WEB COMPRISING MULTILAYER FIBERS [0002]

Melt blowing is a process for forming a nonwoven fibrous web of thermoplastic polymeric fibers. In a typical meltblowing process, one or more molten polymer streams are extruded through a die orifice and attenuated by a converging stream of high velocity air ("blown" air) to form fibers, To form a nonwoven fibrous web. BACKGROUND OF THE INVENTION [0002] Melt blown nonwoven fibrous webs are used in a variety of applications including, in particular, soundproofing materials and insulation, filtration media, surgical drapes, and wipes.

As a general overview, the present disclosure discloses a thermally stable meltblown fibrous web comprising a plurality of the melt-blown multilayered fiber, melt-blown multilayer fiber least selected herein is a polymer which crystallize slowly, having more than about 200 ℃ T _m first It includes a polymer of one or more first layers, and at least one second layer consisting of a polymer of a second polymer which crystallized rapidly with about 200 or more _m ℃ T consisting, respectively. These and other aspects will become apparent from the following detailed description. However, in no event shall the general summary be construed as limiting the gist of the claimed invention, whether presented in the claims of the application as originally filed, or in the claims as amended or otherwise set forth in the proceedings do.

1 is a schematic side cross-sectional view of an exemplary heat-stable melt blown fibrous web portion.
2 is a cross-sectional view of an exemplary melt blown multilayer fiber.
3 is another cross-sectional view of an exemplary melt blown multilayer fiber.
4 is another cross-sectional view of an exemplary melt blown multilayer fiber.

Unless otherwise indicated, all numbers and figures in the specification are not to scale and are selected for the purpose of illustrating different embodiments of the invention. In particular, the dimensions of the various components are shown in exemplary form only, and the relationship between the dimensions of the various components should not be deduced from the drawings unless so indicated. Like numbers refer to like elements in the various figures. Some elements may exist in multiple; It will be appreciated that in such a case, only one or more representative elements may be designated by the drawing numbers, but such numbers apply to all such elements (in some cases, for purposes of illustration only, Can be used for convenience in distinguishing a number of equal elements). The terms "top", "bottom", "upper", "lower", "lower", "above", "forward", "rearward", "outward", "inward", " Quot; first "and" second "may be used in this disclosure, they should be understood to be used only in their relative sense unless otherwise stated. In particular, for an equal number of components, the designations of "first" and "second" can be applied to the order of description, as mentioned herein (which means that one of the components is described first As long as it is chosen to be the best.

The term "substantially ", as used herein as a modifier for a characteristic or attribute, means that, unless otherwise specifically defined, that characteristic or attribute may be used without requiring absolute precision or perfect agreement (e.g., ≪ / RTI > within +/- 20% of the property). The term "substantially" means a high degree of approximation (e.g., within +/- 10% of a quantifiable characteristic) without requiring absolute precision or perfect agreement unless otherwise specifically defined. It is understood that terms such as the same, equal, uniform, constant, strict, etc. are within the ordinary tolerances or measurement errors applicable to the particular environment, rather than requiring absolute precision or perfect agreement. As used herein, terms such as "substantially free "," substantially absent ", and the like are intended to encompass all or part of the entirety of a part of the apparatus, such as may occur, for example, It will be appreciated by those skilled in the art that the present invention does not exclude the presence of an extremely low amount of material, e.g., less than 0.1%.

Term Description

A thermally stable web, when tested as described in the examples herein, refers to a web exhibiting less than 10% heat shrinkage.

Melt blown fibers / web refers to fibers / webs produced by melt blown.

Melt blowing means that the molten fiber-forming material is extruded through a plurality of orifices of the die to provide a molten filament. The filaments are contacted with a high velocity stream of gas (e. G., Air) to attenuate the filaments into (melt blown) fibers immediately after discharge from the orifices and then collected, Same as.

"Filament" means a molten stream of thermoplastic material extruded from a set of orifices; Fiber refers to a solidified filament. The web refers to the collected fiber masses, at least some of which are bonded to each other to a degree sufficient to have sufficient mechanical strength to allow the web to be treated as a conventional roll-to- .

T _m means the crystalline melting point of the semi-crystalline polymer and is measured as described in the examples herein.

The terms " fast crystallizing " and " slow crystallizing " as applied to semi-crystalline polymers are defined and described in detail herein below.

Polymers refer to materials made from macromolecules having a number average molecular weight of at least about 10,000. The term polymer is used for convenience of description and includes, in particular, the presence of a non-polymeric additive (including, for example, often present in thermoplastic polymers for various purposes) Also allow.

Non-polymeric nature means having a number average molecular weight of less than 10,000.

The outside refers to the layer, surface or edge that provides the radially outermost portion of the multi-layered fiber.

DETAILED DESCRIPTION OF THE INVENTION

The present disclosure discloses a heat stable melt blown nonwoven fibrous web 1 as shown in the exemplary embodiment of Fig. The web comprises a plurality of meltblown multilayer fibers (100). Wherein the multilayer comprises two or more layers of fibers; In particular, one or more first layers 110 comprised of a first polymer and one or more second layers 150 comprised of a second polymer. The multilayer further means that each of the at least one first layer 110 and the at least one second layer 150 includes an outer edge and / or a major outer surface. Thus, the definition of the term multi-layer fiber specifically excludes so-called sheath-core fibers in which the core layer does not include the outer edge or major outer surface (e. G., Except sporadic statistical occurrences and defects).

A cross-sectional view of the exemplary two-ply multi-layered fiber 100 (viewed along the direction substantially along the long axis of the multi-ply fibers) is shown in Fig. The fibers 100 include a first polymer layer 110 that includes a major outer surface 118 and an outer edge 116 (in this type of embodiment, a layer portion 110 ) And a portion defined by the outer edge), as well as a major inner surface 112. The fibers 100 further include a second polymer layer 150 that includes a major inner surface 152 and an outer edge 156 and in this embodiment further includes a major outer surface 158 . The primary inner surface 152 of the second polymer layer 150 and the primary inner surface 112 of the first polymer layer 110 are in direct contact with each other at the inner interface 114.

Another exemplary multilayered fiber 100 (in this case, five-ply fibers) is shown in Fig. 3 and again in cross-section. The exemplary five-layer fiber 100 of FIG. 3 has a total of three first polymer layers 110 and two second polymer layers 150, including alternating first and second layers. The first layer 110 includes at least one major inner surface 112 that is in direct contact with a major inner surface 152 of the second polymer layer 150 at the interface 114 (two such interfaces, And the major inner surfaces of layers 110 and 150 are shown in Figure 3 as (114 and 114 ', 112 and 112', and 152 and 152 '). In this general type of multi-layered fibers (e.g., three or more first layers 110 and two or more second layers 150), one or more first layers 110 are formed on the inner first layer Quot; 110i "), which means that such a first layer is sandwiched between the two second layers 150. The first layer 110 may be an outer first layer 110e in Figure 3 that is in direct contact with the major inner surface 152 of the second layer 150 at the interface 114, And includes another major surface that is a major outer surface 118. The major outer surface 118 is a major outer surface. The first layer 110 of multilayered fibers will represent the outer edge 116 (two such edges 116 and 116 'are shown in Figure 3), the major outer surface 118, or both. For example, in the case of multi-layered fibers having several layers (as indicated above), there may not be a clear dividing line between the portion of the first layer designated as the major outer surface and the portion named as the outer edge, In this presence, the outer edge can be more easily distinguished from the major outer surface (e.g., of the outer first layer). Again, the second layer 150 of the multilayered fibers will, by design, represent the outer edge 156 (two such edges 156 and 156 'are shown in FIG. 3).

Another exemplary multilayer fiber 100 (in this case 15-layer fiber) is shown in Fig. 4 and again in cross-section. The exemplary 15-layer fiber 100 of FIG. 4 includes eight (six internal and two external) first polymer layers 110 and seven second polymer layers 150. In a more general aspect, the multi-layered fiber may comprise n or more first layers and n-1 or more second layers, wherein n-2 or more of the second layers are individually disposed between a pair of first layers , Wherein n is a number from 3 to 51. [ (As used herein, interleaving means that there is no other second layer between a particular pair of specific first layers.)

It should be understood from the above description that multilayer fibers such as those defined herein may be used in combination with one or more, and often several, or more (e.g., five, ten or more) internal interfaces between the first and second layers 110 and 150 (S) 114, which will substantially extend along the long axis of the multi-layered fibers in a predetermined and essentially continuous manner. That is, in the multi-layered fibers as defined herein, the first and second layers and the interface therebetween are essentially continuous and extend essentially along the entire length of the multi-layered fibers in a continuous manner (actual melt blown Such sporadic variation, interruption, etc., as is understood to be statistically present in any fiber produced by the process. Thus, the multi-layer fibers as disclosed herein are distinguished from single layer fibers comprising a blend of semiconducting polymers (wherein the two polymer phases are such that one polymer phase is dispersed in the other polymer phase, Islands, spheres, tendrils, and the like in a somewhat random manner. Those skilled in the art will recognize that even though blended-polymer fibers may sometimes exhibit a single polymeric phase extending to some extent along the long axis of the fiber, such unstable and unpredictable cases can be identified with the intended multilayered fibers as disclosed herein I will understand.

In many embodiments, the interface 114 between the first and second layers may be plane, on average, substantially or even substantially (as in the depictions of Figures 2 to 4). It should be noted, however, that the description of FIGS. 2-4 is ideal, and that in actual practice the surface and interface must be strictly planar at all locations, or that the fibers 100 need not necessarily be completely round. Further, although a general type multi-layer fiber having two first layers 110 and one second layer 150 sandwiched therebetween is not shown in the drawings, the disclosure of this specification is understood to cover such a structure. Similarly, multilayer fibers having an even number of second layers or multilayer fibers having a number of second layers equal to or greater than the first layer are not shown in these figures, but such a manner is encompassed by the disclosure of the present disclosure.

In at least some embodiments, the first layer (s) 110 and the second layer (s) 150 are each a single component layer. A single component layer is a layer having essentially the same composition over the thickness, width and length of the layer; The single-component layer may include additives, etc., as long as the composition is substantially uniform across the thickness, width, and length of the fibers (except for such sporadic statistical variations that those skilled in the art will understand exist in any actual manufacturing process). In some embodiments, the first polymer is a polymeric component of only the first layer 110 and the second polymer is a polymeric component of the second layer 150 alone.

The average diameter of the meltblown multilayer fibers (as measured by, for example, optical microscopy, by sampling representative fibers) may be within any desired range. Melt blowing is particularly suitable for the formation of so-called microfibers (meaning fibers with an average diameter of less than 10 micrometers (μm)) due to the tendency of high-speed "blown" air to reduce the diameter of the melted filaments Will be understood. Thus, in various embodiments, the melt-blown multilayer fibers may have an average diameter of less than about 30 占 퐉, 20 占 퐉, 15 占 퐉, 10 占 퐉, 5 占 퐉, 2 占 퐉, or 1 占 퐉. In a further embodiment, the melt-blown multilayer fibers may have an average diameter of about 0.5 [mu] m, 1 [mu] m, 2 [mu] m,

Multilayer fiber 100 is at least about 200 ℃ T _m of at least one comprising a first polymer having a first layer 110, and at least about 200 ℃ T _m for the at least one comprising a second polymer having a second Layer 150 as shown in FIG. This means that both the first polymer and the second polymer should be able to exhibit a crystalline melting point T _m under at least some conditions (above about 200 캜). That is, such polymers must be capable of forming a significant number of crystalline domains (e. G., Under slow cooling conditions); The terms first and second polymers are not meant to encompass essentially amorphous polymers that will not form significant crystalline domains, for example, although they may be very slowly cooled to exhibit well-defined crystalline melting points. In various embodiments, the first polymer may exhibit about 210 ℃, more than 220 ℃, 230 ℃, 240 ℃ , 250 ℃ or 260 ℃ T _m. In various embodiments, the second polymer may exhibit more than T _m of about 210 ℃, 220 ℃, 230 ℃ , 240 ℃, 250 ℃ or 260 ℃.

The first and second polymers are different in that the first polymer is a slow crystallizing polymer and the second polymer is a fast crystallizing polymer. Briefly, a rapidly crystallizing polymer forms a crystallization zone at a sufficiently rapid rate under relatively rapid cooling conditions used in conventional meltblowing processes, so that the solidified meltblown fibers can be displayed when the polymer is subjected to a slower cooling process ≪ RTI ID = 0.0 > and / or < / RTI > In contrast, the slowly crystallizing polymer forms a crystallization zone at a sufficiently slow rate under the cooling conditions used in a conventional melt-blowing process so that the solidified melt-blown fibers have a value that is less than a value that can be exhibited when the polymer is subjected to a slower cooling process Quot; means a polymer that exhibits a significantly lower degree of crystallinity.

The polymer can be screened with slow crystallizing properties and fast crystallizing properties according to the following manner. The polymer sample may first be subjected to a first heating step above T _m to remove any existing thermal history in the sample. This sample with a standard thermal history added to it can then be subjected to a slow cooling process (for this purpose, a cooling rate of 10 ° C per minute may be taken). The sample is cooled to a temperature sufficiently lower than T _m (e.g., to room temperature). The sample is then processed in a second heating step (e.g., at 10 [deg.] C per minute) above T _m . The heat of the melting and cooling crystallization is then calculated from the data obtained from the second heating step and the degree of crystallinity (% crystallinity) is calculated therefrom. (These measurements and calculations may be made using any suitable differential scanning calorimetry (DSC), for example, DSC as a "troubleshooting tool ", which is incorporated herein by reference in its entirety: measurement of percent crystallinity of thermoplastic resin Problem Solving Tool: Measurement of Percent Crystallinity of Thermoplastics ", Perkin-Elmer (2000)).

Another sample of the polymer can be similarly treated in a first heating step above T _m to eliminate any existing thermal history in the polymer. This sample with a standard thermal history added to it can then be subjected to a rapid cooling process (for this purpose, a cooling rate of 200 ° C per minute can be taken). The second heating step is then carried out and the degree of crystallinity calculated for the rapidly cooled sample can be calculated in a manner analogous to that discussed above.

The degree of crystallinity for a rapidly cooled sample and a slowly cooled sample can then be compared. The difference in degree of crystallinity between about 20% or more under rapidly cooled conditions versus slowly cooled conditions represents a slowly crystallizing polymer. In certain embodiments, poly (ethylene terephthalate) (PET) is a prototypical slowly crystallizing polymer as defined herein. PET can form a crystalline domain and can often exhibit a degree of crystallinity in the range of well defined T _m in the range of about 250 to 260 ° C and in the range of, for example, 30% or 40% or more after being slowly cooled from the melt. However, when rapidly cooled from the melt as described above, PET can exhibit degrees of crystallinity in the range of less than 30% (often significantly less).

In contrast, poly (butylene terephthalate) is a circular, rapidly crystallizing polymer, which typically exhibits a similar degree of crystallinity (e.g., within about 10% of each other) whether rapidly cooled or slowly cooled will be.

DSC screening as described above may be useful in identifying potentially useful first and second polymers. However, for the purposes used herein, the first polymer or the most convenient method is the polymer to be evaluated (under the assumption that meet the first criteria of possible T _m identification of over 200 ℃) to determine the semi-crystalline polymer as a second polymer (Not multi-layer) melt blown fibers of a single component. Including but not limited to extruder temperature, die and blowing air, volume ratio and linear velocity of blowing air, distance from die to collector, etc., which are within the usual range for melt blowing of that particular material Which will be well understood by those skilled in the art). (Examples of typical melt blowing conditions for a given polymer are found in the examples herein.)

A single component test web produced in such a manner can then be treated with a heat shrinkage test as described in the examples herein. A polymer that exhibits a heat shrinkage of less than 10% as a single component melt blown web is a second polymer as defined herein (i.e., so long as the other meets the criteria set forth herein). In various embodiments, the second polymer may exhibit a heat shrinkage of less than 8%, 6%, 4% or 2%. A polymer that exhibits a heat shrinkage of greater than 10% as a melt blown homopolymer web (i. E., As long as the other meets the criteria set forth herein) is a first polymer as defined herein. In various embodiments, the first polymer may exhibit a heat shrinkage of greater than about 20%, 30%, 40% or even 50%.

Suitable first polymers such as poly (ethylene terephthalate), poly (ethylene naphthalate), poly (trimethylene terephthalate) and at least some of the polylactic acid, which may indicate a T _m of the same polyester and 200 ℃ excess ( For example, those having a relatively high content of D-lactide). Any desired combination of such first polymers may be used. Suitable second polymers may be selected from, for example, polyesters such as poly (butylene terephthalate), polyolefins such as polymethylpentene, and other polymers such as syndiotactic polystyrene, and any desired combination thereof.

The first polymer and the second polymer are present in a weight ratio of about 95: 5 to about 45:55 (first: second), based on the total weight of the first polymer and the second polymer in the meltblown fibers of the web Which does not include any first or second polymer that may be present in the staple fiber, including but not limited to any polymer of any type that may be present in the single component melt blown fibers present in the multi-layer fibers . In various embodiments, the weight ratio of the first polymer to the second polymer can be about 50:50, 60:40, 70:30, 75:25, 80:20, 85:15, or 90:10 or more. In a further embodiment, the weight ratio of the first polymer to the second polymer may be about 90:10, 85:15, 80:20, 75:25, 70:30, 60:40 or 50:50 or less.

As described in detail below, the approach disclosed herein achieves significant advantages over possible performance with the use of the first polymer alone, while enabling the use of a relatively small amount (wt.%) Of the second polymer do. Such a scheme may be used, for example, to provide at least a portion of the first layer 110 with at least a thickness of at least a portion of the second layer 150 (i. E., An average distance between the major surfaces 152 and 152 ' (I.e., the average distance between the major surfaces 112 and 112 ', as also shown in FIG. 3). In such a manner, one or more second layers may be provided, while minimizing the total amount of second polymer used for the total amount of first polymer used. Thus, in various embodiments, the ratio of the thickness of the first layer (s) 110 to the thickness of the second layer (s) 150 is about 1.2: 1, 1.5: 1, 2: 1, 3: Lt; / RTI > (In such a calculation, the thickness of the outer layer (for example, 110e in FIG. 3) having an arcuate major surface can be regarded as the thickness of a rectangular area having the same cross-sectional area as the outer layer.

It has been found that the inclusion of one or more second layers of a rapidly crystallizing second polymer can significantly accelerate the crystallization of the slowly polymerizing first polymer, even under relatively rapid cooling conditions as prevailing in melt blowing. This can provide a solidified product comprising a first polymer having a significantly increased degree of crystallinity and as a result can provide a melt blown web exhibiting a much lower heat shrinkage than is possible, Can be provided. Advantageously, this can be achieved, for example, by using fewer and / or thinner layers of the second polymer, so that the total weight ratio of the second polymer to the first polymer, as indicated above, can be maintained at a relatively low level have. Such a second polymer is often much more expensive than the first polymer, which can provide a significant benefit.

Also, inclusion of one or more second polymers in the form of one or more layers, as described herein, means that the second polymer is in the form of, for example, a polymer blend and is physically intimately mixed with the first polymer , ≪ / RTI > melt-blended), the crystallization of the first polymer can be accelerated better. This is an amazing result. It will be appreciated by those skilled in the art that the acceleration effect of the second polymer can be induced through the (rapidly crystallizing) surface of the second polymer that provides nucleation sites for the first polymer at the interface of the first and second polymers . Thus, a second polymer, which can be expected to have a dispersion of the second polymer in the first polymer in the form of a number of parcels (e.g., in the form of a tangle or sphere, possibly up to the macromolecular slice) With the first polymer as a blend achieves a significantly higher surface area of the second polymer in the first polymer and thus comprises a second polymer in the form of a layer as disclosed herein, Will be more effective in accelerating the crystallization of < / RTI > However, the embodiments presented herein are particularly advantageous when the weight ratio of the second polymer to the first polymer is similar or lower, such that the multi-layer melt blown fibers as disclosed herein are lower than the blended-polymer melt blown single layer fibers Heat shrinkage rate. This is therefore an unpredictable beneficial result.

In some embodiments, the web 1 may additionally include optional staple fibers 200, as shown in the exemplary embodiment of FIG. In web 1, staple fibers 200 are distributed throughout the network of meltblown fibers and mixed therein. In various embodiments, the staple fibers 200 comprise about 5%, 10%, 20%, 30% or 30% by weight of the total weight of the fibrous material (e.g., the sum of meltblown fibers and staple fibers) 40% by weight or more. In a further embodiment, the staple fibers 200 can constitute up to about 60%, 50%, 40%, 30%, or 20% by weight of the total weight of the fibrous material of the web.

Regardless of its particular manufacturing process or composition, staple fibers are typically added to the nonwoven web in a machine cut and solidified form to a predetermined or identifiable length. The length of the staple fibers is often much less than the length of the meltblown fibers; In various embodiments, from about 1 cm to about 8 cm, or from about 2.5 cm to about 6 cm. The average fiber diameter of the staple fibers is often on the average greater than about 15 microns, and in various embodiments may be greater than 20 microns, 30 microns, 40 microns, or 50 microns. Thus, in many embodiments, the average fiber diameter of the staple fibers may be about 2, 4, or 8 times the average diameter of the melt-entrained multilayer fibers.

In some embodiments, the staple fibers may comprise a synthetic polymeric material. In some embodiments, the staple fibers may comprise natural fibers (selected from fibers derived from, for example, bamboo, cotton, wool, jute, agave, sisal, coconut, soybean, hemp, etc.). If desired, at least some of the composition of the staple fibers may be selected such that they can be melt bonded to each other and / or melt blown fibers during a molding process (such as may be used to form a molded article comprising a meltblown web) . Alternatively, they may be made of a material having properties (e.g., melting points) that prevent it from bonding to each other or to the melt blown fibers during the molding process.

Suitable staple fibers may be prepared from, for example, any suitable polyester and its copolymers, polyolefins such as polyethylene, polypropylene and its copolymers, polyamides, or any combination thereof. The staple fibers can be, for example, crimped fibers as described in U.S. Patent No. 4,118,531 to Hauser. The crimped fiber can have a continuous wavy, curly or jagged profile along its length. The staple fibers may comprise, for example, crimped fibers comprising from about 10 to 30 crimps per cm. The staple fiber can be a single component fiber or a multicomponent fiber.

As required for various purposes, various other components may be present in the web 1, particularly in the melt-blown multilayer fiber 100. For example, any desired type of particulate additive may be present in the web 1. In particular, when the web 1 is used for filtration purposes, particulate additives such as any suitable absorbent, catalytically reactive, chemically reactive, etc. may be present. The melt blown multi-layer fiber 100 may have any suitable auxiliary component present therein. Such constituents may be present, for example, in the first polymer and / or the second polymer described above as obtained, and may include, for example, processing additives, antioxidants, UV stabilizers, refractory additives, and the like . In some embodiments, the first polymer may include one or more non-polymeric nucleating agents (e.g., melt additives), which may include, for example, various stearates, carboxylic acid salts, nitrogen-containing heteroaromatic compounds, Lt; / RTI > However, in certain embodiments, the first polymer comprises about 5 wt%, 2 wt%, 1 wt%, or less than 0.5 wt% of any non-polymeric nucleating agent. In certain embodiments, the first polymer is substantially free of any non-polymeric nucleating agents.

In some further embodiments, the web 1 comprises at least some amount of a polymeric nucleating agent, in the form of a separate layer of the multi-layered fibers, or as a blend of the first or second polymer or the like (e.g., as a melt additive) Regardless of whether or not it is. Such materials may include, for example, polyester-sulfonate salts, polypropylene, certain polyolefins such as polyethylene, and copolymers and blends thereof. However, some such materials may exhibit a T _m of less than 200 ℃, therefore to be understood that as described herein can not be regarded as the second polymer. However, such materials nevertheless provide benefits, as long as they do not exist in amounts that affect the heat shrinkage unacceptably, for example in the resulting web. Thus, in various embodiments, the multi-layered fiber 100 may comprise about 5 wt.%, 2 wt.%, 1 wt.% Or 0.5 wt.% Of any polymeric nucleating agent. In certain embodiments, the multi-layered fiber 100 is substantially free of any polymeric nucleating agent.

In some embodiments, it may be advantageous to minimize the amount of polymeric material having a T _m of less than 200 ℃ meltblown fibers in the web. (And in this context, the term polymeric material exhibiting a T _m of less than 200 ℃ not only specifically comprise only a single polymer chain of the polymeric material, including any polymer segment of such materials that may be present in the copolymer .) Thus, in various embodiments, any polymeric material having a T _m of less than 200 ℃ (e.g., including staple fibers) of about 20% by weight, based on the total fibrous material in the web, 10 weight percent , 5 wt%, 2 wt%, 1 wt%, or less than 0.5 wt%. In a further embodiment, meltblown fibrous web is a polymeric material having less than 200 ℃ T _m substantially free. In some embodiments, in particular in the meltblown fibers of the web, it may be beneficial to minimize the amount of polymeric material having a T _m of less than 200 ℃. Thus, in various embodiments, any polymeric material having a T _m of less than 200 ℃ (including the meltblown fibers non-random multi-layer) of about 20% by weight in the melt blown fibers of the web, 10 weight%, 5 By weight, 2% by weight, 1% by weight or less than 0.5% by weight. In a further embodiment, the meltblown fibers of the web is a polymeric material having a T _m of less than 200 ℃ substantially free.

In various embodiments, the web 1 as disclosed herein can be characterized as comprising about 10%, 8%, 6%, 4%, 2% or 1% (measured as disclosed in the examples herein) Lt; / RTI > As discussed herein, such characteristics may provide significant advantages in certain applications.

As shown, the nonwoven web disclosed herein employs melt blown fibers as defined above. Those skilled in the art will recognize that meltblowing processes and the meltblown fibers and meltblown nonwoven webs formed by such processes can be used to produce processes such as melt spinning and the resulting products such as meltblown fibers and melt spinning (e. G., Spunbonded) You will understand that it is distinct from the non-woven web. The term " melt spinning " and " melt spinning " are technical terms used to refer to forming fibers by extruding molten filaments from a set of orifices and cooling and solidifying the filaments to form fibers, (Which may include a stream of moving air) to aid in cooling the air. The cooled filaments are then passed in a stretch unit to at least partially stretch the filaments (e.g., to induce orientation and enhanced physical properties). Thus, the melt blowing may be accomplished by a converging high velocity air stream introduced by air-blowing openings (e.g., air knife) positioned very close to (e.g., within 1 cm) the extrusion orifice The melt spinning can be distinguished from the melt spinning in that it involves extruding the molten filament into the melt. Thus, those skilled in the art will understand that melt blowing and melt spinning impart different characteristics (e.g., characteristics in molecular orientation and resultant physical properties) to the resulting web and the web (even if the fiber / web is similar in composition) , So that it will be appreciated that melt-blown fibers and melt-spun fibers can easily be distinguished from each other.

Thus, the melt blown fibers disclosed herein include a meltblown die capable of releasing molten multi-layered filaments therefrom, a high-speed "hot melt " die to attenuate the filament into meltblown fibers immediately after the essentially molten multi-layer filaments exit the orifice of the meltblown die. (E.g., extruders, temperature control equipment, etc.) as conventionally used in meltblowing and collecting for the collection of meltblown fibers, as well as for blowing air on the melted filaments .

Such devices are described, for example, in van Wente, "Superfine Thermoplastic Fibers ", Industrial Engineering Chemistry , Vol. 48, pages 1342 et sec (1956)] or in the report [Report No. 1]. 4364 of the Naval Research Laboratories, May 25, 1954 entitled "Manufacture of Superfine Organic Fiber" by van Wente, A. Boone, CD, and Fluharty, EL. Such a device may be modified for a particular purpose to produce a multi-layer melt blown fiber, for example, a feed block (e.g., a feed block), wherein the first and second flow streams are then combined into a single, the first and second extruders supplying the first and second flow streams of the molten polymer into the feedblock, respectively. Methods and apparatus that can be used to produce multilayer melt blown fibers are discussed in further detail in, for example, US Patent Nos. 5,207,790 and 5,232,770 to Joseph. It will be apparent that the multi-layer fibers produced in this manner are, for example, separated from the blended-polymer monolayer fibers extruded through a common orifice, and then the two molten polymers are combined into a single blended flow stream in a single extruder . The multi-layer fibers produced in this manner are formed by extruding a first molten polymer stream from a first inner orifice and a second molten polymer stream being extruded through a second orifice annularly enclosing an inner orifice, It is additionally clear that it is different from

In some embodiments, melt blown multi-layer fibers can be collected on a flat surface (e.g., a porous collection belt or netting) or on the surface of a single collection drum. In another embodiment, meltblown multi-layer fibers can be collected between the converging collection surfaces, e.g., within the gaps between the first and second collection drums. Such a method may provide that the melt blown fibers 100 are present in the web 1 at least in a substantially or substantially "C" -shaped cross-sectional configuration. Such a scheme (described in detail in US Patent No. 7,476,632 to Olson, incorporated herein by reference in its entirety) may provide increased loft and / or other advantageous properties.

In at least some embodiments, the staple fibers may optionally be incorporated into the meltblown web as indicated above. This can be done, for example, by injecting an airborne stream of staple fibers into an air-mediated stream of attenuated filaments / fibers. (The process of solidifying the molten filament during its movement from the die orifice to the collector to form the fiber will be a statistical process, so the filaments and fibers can be used interchangeably somewhat at this stage of the process.) This is because the multi- Fibers and staple fibers, which air stream can be impinged on the collector to collect mixed multi-layer melt blown fibers and staple fibers as a fiber agglomerate. Apparatus and processes for injecting staple fibers into a stream of melt blown fibers, for example, are described in further detail in U.S. Patent Nos. 7,989,371 to Angadjivand and U.S. Patent No. 4,118,531 to Hauser.

In some embodiments, at least some of the staple fibers can act as binding fibers as indicated above. Alternatively, or as an aid to this, at least some of the melt-blown fibers may be bonded (e.g., depending on the collection manner, etc.), for example, melt-bonded to each other. If desired, any suitable post-bonding process may be used (e.g., point-to-bond through calendering operations, etc.).

The meltblown fibrous webs described herein can be incorporated into articles such as thermal insulation and soundproofing articles, manufactured liquid and gas filters and the like (e.g., as webs, sheets, scrims, fabrics, etc., ). While any suitable use may be embodied, the resistance to heat shrinkage of the meltblown web may make such articles particularly suitable for use in relatively hot environments. Such articles find use in a wide variety of applications, for example in soundproofing and / or insulation in vehicles or building components, personal protective equipment or clothing. It should be noted that such meltblown webs may be particularly useful in adiabatic and / or high temperature soundproofing articles, and that such articles may perform two functions in some applications (e.g., automotive hoodliners). The melt blown fibrous web 1 may be combined with any desired additional layer (e.g., scrim, facing, etc.), which may be advantageous for forming a particular article. The web 1 may be processed (e.g., shaped, cut, etc.) with any such additional layer to form articles of a particular construction.

List of exemplary embodiments

Embodiment 1 is one consisting of the polymer of the first polymer to crystallize slowly with heat as a stable meltblown fibrous web, where at least selected meltblown multilayer fiber is at least about 200 ℃ T _m in which a plurality of the melt-blown multilayered fiber over the first layer, and at least about 200 ℃ T _m quickly least one consisting of a second polymer having a polymer to crystallize a second layer, respectively, and the multilayer meltblown fibers is from about 45:55 to about 95:05 Wherein said thermally stable melt blown fibrous web is a heat stable melt blown fibrous web exhibiting less than about 10% heat shrinkage.

Embodiments 2, in the embodiment 1, the first polymer represents at least about 240 ℃ T _m, the second polymer is thermally stable meltblown fibrous web representing at least about 240 ℃ T _m.

Embodiment 3 is the heat stable melt blown fibrous web of Embodiment 1 or Embodiment 2, wherein said melt blown fibers represent an average weight ratio of the first polymer to the second polymer of from about 60:40 to about 90:10.

Embodiment 4 is a process according to embodiment 1 through 3 wherein the meltblown fibers are heat stable melt blown fibers that exhibit an average weight ratio of the first polymer to the second polymer of from about 70:30 to about 80:20 Web.

Embodiment 5 is a process of any one of Embodiments 1 to 4 wherein said first polymer is selected from the group consisting of poly (ethylene terephthalate), poly (ethylene naphthalate), poly (lactic acid), poly (trimethylene terephthalate) Lt; RTI ID = 0.0 > meltblown < / RTI > fibrous web.

Embodiment 6 Embodiment 6 is the heat stable melt blown fibrous web according to any one of Embodiments 1 to 4, wherein the first polymer is poly (ethylene terephthalate).

Embodiment 7 is a heat stable melt blown fibrous web as in any of embodiments 1 to 6 wherein the first polymer is substantially free of non-polymeric nucleating agents.

Embodiment 8 is a process of any one of embodiments 1 to 7 wherein the second polymer is a thermally stable melt blown fibrous material selected from the group consisting of poly (butylene terephthalate), polymethylpentene, and syndiotactic polystyrene Web.

Embodiment 9 is a process according to any one of Embodiments 1 to 8, wherein said at least selected multi-layer fibers have a thermal stability comprising at least one pair of first layers sandwiched by a second layer therebetween, Melt blown fibrous web.

Embodiment 10 is a combination according to any of Embodiments 1 to 8, wherein said at least selected multi-layered fiber comprises at least three first layers and at least two second layers, Thermally stable melt blown fibrous web sandwiched between the first layers of the pair.

Embodiment 11 Embodiment 11 is according to any of Embodiments 1 to 8, wherein said at least selected multi-layered fiber comprises at least five first layers and at least four second layers, wherein each second layer comprises one Thermally stable melt blown fibrous web sandwiched between the first layers of the pair.

Embodiment 12 is a process as set forth in any of Embodiments 1 through 8 wherein said at least selected multi-layered fiber comprises at least n first layers and at least n-1 second layers, wherein n Wherein at least two are individually sandwiched between the first layers, wherein n is a number from 7 to 51.

Embodiment 13 is a heat stable melt blown fibrous web according to any one of Embodiments 1 to 12, wherein the first layer is a single component layer and the second layer is a single component layer.

Embodiment 14 is a heat stable melt blown fibrous web as in any of Embodiments 1 to 13, wherein the plurality of meltblown fibers collectively exhibit an average fiber diameter of less than about 10 占 퐉.

Embodiment 15 is Embodiment 15 wherein, in any of Embodiments 1 to 14, the web further comprises staple fibers, wherein the staple fibers comprise from about 5% to about 50% by weight of the total weight of fibrous material of the web % ≪ / RTI >

Embodiment 16 is the heat stable melt blown fibrous web of any one of Embodiments 1 through 15 wherein the web exhibits less than about 6% heat shrinkage.

Embodiment 17 is the heat stable melt blown fibrous web of any one of Embodiments 1 through 15 wherein the web exhibits less than about 2% heat shrinkage.

Embodiment 18, embodiment 1 to embodiment according to any one of 17, heat stability melting meltblown fibers of the web may comprise any polymeric material which is less than 200 ℃ T _m to about 5 wt% It is a blown fibrous web.

Embodiment 19, embodiment 1 according to any one of to embodiment 17, the meltblown fibers of the web is any polymeric material is thermally stable meltblown fibrous web is substantially free of having less than 200 ℃ T _m.

Embodiment 20 is an article comprising a heat stable melt blown fibrous web of any one of Embodiments 1 to 19, wherein the article is selected from the group consisting of adiabatic article, soundproof article, fluid filtration article, to be.

Embodiment 21 is the article of embodiment 20 wherein the article is a soundproof article that exhibits less than about 5% heat shrinkage.

Embodiment 22 comprises the steps of extruding a molten multi-layer flowstream through an orifice of a meltblowing die to form a molten multi-layer filament;

Damping said molten multi-layer filaments using a high velocity gas stream to form multi-layer melt blown fibers; And

Collecting the multi-layer melt blown fibers as a fiber agglomerate,

At least selected multi-layered melt of the collected lump of the fiber flow stream where the blown fibers are at least about 200 ℃ T _m a slow crystallizing polymer is melt the at least one or more first layers and about 200 ℃ consisting of one polymer having T _{lt; RTI ID = 0.0 > m} , < / RTI >

Embodiment 23 is Embodiment 23 wherein, in embodiment 22, the attenuated multilayer filaments form an air-entrained stream of multilayer meltblown fibers, the method comprising injecting an air-borne stream of staple fibers into the air- And collecting the intermixed multilayer melt blown fibers and staple fibers as a fiber agglomerate.

Embodiment 24 is the method of embodiment 22 or embodiment 23, wherein the method further comprises bonding at least a portion of the fibers in the fiber agglomerate together to form a heat-stable melt blown fibrous web.

Embodiment 25 is a heat stable melt blown fibrous web of any one of Embodiments 1 to 19 prepared by any one of Embodiment 22 to Embodiment 24. [

Embodiment 26 is the article of Embodiment 20 or Embodiment 21 produced by any one of Embodiment < RTI ID = 0.0 > 22 < / RTI >

Example

Test Methods

Heat shrinkage

The heat shrinkage of the melt blown web can be obtained using three 10 cm x 10 cm samples. The dimensions of each specimen are typically measured before and after placement in a Fisher Scientific Isotemp Oven (or equivalent) at 180 ° C for 15 minutes in both machine direction (MD) and transverse direction (CD) do. The shrinkage percentage for each sample is calculated by the following equation in MD and CD:

Where L ₀ is the initial specimen length and L is the final specimen length. Calculate and report the mean value of shrinkage.

T _m (Crystalline melting point)

T _m of the polymer samples can be obtained by using a tieyi Instruments (TA Instruments) The differential scanning calorimetry (MDSC), or equivalent control Q2000. The specimens were weighed and loaded into a compatible aluminum pan. Heating the sample by applying a first heated to a temperature greater than the estimated T _m of the sample and; Thereafter, the sample is cooled at a sufficiently slow rate (e.g., 10 [deg.] C per minute) to cause crystallization to occur. After these initial heating / cooling steps, the second heating is applied, for example, at a heating rate of 10 [deg.] C per minute and the heat flow is observed. The crystalline melting point T _m can be obtained from the second heating data as a peak of a well defined primary melting peak (if such a peak exists), which will be well understood by those skilled in the art.

Apparatus and method for manufacturing melt blown web

A melt blown web was prepared according to Wente, Van A., "Superfine Thermoplastic Fibers" in Industrial Engineering Chemistry , Vol. 48, pages 1342 et seq (1956); 4364 of the Naval Research Laboratories, published May 25, 1954 entitled "Manufacture of Superfine Organic Fibers" by Wente, Van. A. Boone, CD, and Fluharty, EL. The apparatus utilized an extruder equipped with a gear pump to control the polymer melt flow and distribute it to a melt blowing die having a circular smooth surface orifice with a length to diameter ratio of 5: 1. The orifices were arranged in a linear fashion on the die face at intervals of 10 orifices per cm. The air-feeding device (air knife) is provided on the die face in order to collide the high-speed "blown" air in such a way that the molten filament converges to the melt filament immediately after it is essentially discharged from the orifices of the melt- do.

In the case of the multilayer fibers of the Examples, the apparatus was modified to include two extruders (in a manner analogous to that disclosed in U.S. Patent No. 5,207,970), each extruder having a gear Pump, and each extruder is configured to feed the molten extruded product to a split feed block similar to that described in US Pat. No. 3,480,502 to Chisholm and US Pat. No. 3,487,505 to Shrenk. The split feed block is configured such that the multilayer molten polymer stream is delivered to the melt blowing die generally as described above.

Representative Embodiment

Example  One

A melt blown fibrous web comprising a plurality of melt blown multi-layer fibers was prepared using the apparatus described above and the general method, operating as described below. The first polymer was a poly (ethylene terephthalate) (PET; 0.54 intrinsic viscosity) resin obtained under the tradename N211 from Nan Ya Plastics Corporation, America, Livingstone, NJ. The second polymer was poly (butylene terephthalate) (PBT) obtained under the tradename Valox -195-1001 from SABIC Innovative Plastics, Pittsfield, MA.

The first and second extruders delivered the PET and PBT melt streams, respectively, to the feed block. The gear pump was adjusted so that a 75:25 PET: PBT weight ratio polymer melt was delivered to the feed block and a total polymer throughput rate of 0.175 kg / hr / cm die was maintained in the meltblowing die. The die was maintained at about 305 占 폚 and the feed block was maintained at about 305 占 폚; The extruder melt temperature (close to the discharge end of each extruder barrel) was maintained at about 305 ° C and 270 ° C in the first extruder and the second extruder, respectively. The air knife gap width of the blown air supply was about 0.76 mm; The temperature of the high-velocity inlet air was maintained at a set point of about 400 ° C and the pressure was suitable for producing a uniform web. The molten stream emerged as a five-layer molten stream in alternating fashion upon discharge from the feed block, the first, third and fifth layers were PET, and the second and fourth layers were PBT.

The melt blown multilayer fibers thus formed were collected on a breathable belt with a DCD of about 38 cm (distance from the die to the collector). The fiber agglomerates thus formed were found to exhibit sufficient mechanical integrity to be provided as self-supporting nonwoven webs; Ancillary join operations were not performed. The meltblown multilayer fiber comprised five alternating layers (the first layer of three PETs and the second layer of two PBTs). The melt blown multi-layer fibers exhibited an average diameter of less than about 10 占 퐉; The melt blown fibrous web had a basis weight of about 130 g / m < 2 >.

Example  2

A melt blown fibrous web comprising a plurality of melt blown multilayer fibers was prepared in a substantially similar manner to Example 1, except that the gear pump was adjusted to deliver a 50:50 PET: PBT weight ratio of polymer melt. The die and feed block were both maintained at about 280 ° C; The melting temperatures of the first and second extruders were about 280 ° C and 270 ° C, respectively. The temperature of the fast blown air was maintained at a set point of about 390 ° C. The melt blown multilayer fibers thus formed were collected at a DCD of about 30.5 cm (distance from the die to the collector). The melt blown multi-layer fibers exhibited an average diameter of less than about 10 占 퐉; The melt blown fibrous web had a basis weight of about 130 g / m < 2 >.

Example  3

Except that the second polymer is polymethylpentene (PMP; obtained under the tradename TPX from Mitsui Chemicals, Liebruck, NY) rather than poly (butylene terephthalate), a plurality of melt- Lt; / RTI > was prepared in a manner analogous to Example 1, generally. The first polymer: second polymer (PET: PMP) weight ratio was about 75:25 and the total polymer throughput rate of 0.14 kg / hr / cm die width was maintained in the meltblowing die.

The die and feed block were both maintained at about 300 ° C; The melting temperatures of the first and second extruders were about 285 ° C and 300 ° C, respectively. The temperature of the high-speed blowing air was maintained at a set point of about 400 ° C. The melt blown multilayer fibers thus formed were collected at a DCD of about 15 cm (distance from the die to the collector). The meltblown multilayer fiber comprised five alternating layers (the first layer of three PETs and the second layer of two PMPs). The melt blown multi-layer fibers exhibited an average diameter of less than about 10 占 퐉; The melt blown fibrous web had a basis weight of about 90 g / m < 2 >.

Example  4

A melt blown fibrous web comprising a plurality of melt blown multilayer fibers was prepared in a substantially similar manner to Example 3, except that the first: second (PET: PMP) weight ratio was about 90:10.

Example  5

A melt blown fibrous web comprising a plurality of meltblown multilayer fibers was prepared in a substantially similar manner to Example 3, except that the first: second (PET: PMP) weight ratio was about 80:20.

Example  6

A melt blown fibrous web comprising a plurality of melt blown multilayer fibers was prepared in a substantially similar manner to Example 3, except that the first: second (PET: PMP) weight ratio was about 70:30.

Example  7

A melt blown fibrous web comprising a plurality of melt blown multilayer fibers was prepared in a substantially similar manner to Example 3, except that the first: second (PET: PMP) weight ratio was about 60:40.

The webs of Examples 4 to 7 were about 90 g / m2 And contained meltblown multilayer fibers having an average diameter of less than about 10 [mu] m.

Example  8

Meltblown fibers comprising a plurality of meltblown multilayer fibers, except that the split feedblock is constructed such that the multilayer fibers comprise 17 alternating layers (the first layer of 8 PETs and the second layer of 9 PMPs) The web was prepared in a substantially similar manner to Example 3. The PET: PMP weight ratio was maintained at about 75:25. The die and feed block were both maintained at about 300 ° C; The melting temperatures of the first and second extruders were about 285 ° C and 300 ° C, respectively. The temperature of the high-speed blowing air was maintained at a set point of about 400 ° C. The melt blown multilayer fibers thus formed were collected at a DCD of about 15 cm (distance from the die to the collector).

Example  9

Meltblown fibers comprising a plurality of meltblown multilayer fibers, except that the split feedblock is constructed such that the multilayer fibers comprise two alternating layers (the first layer of one PET and the second layer of one PMP) The web was prepared in a substantially similar manner to Example 3. The PET: PMP weight ratio was maintained at about 75:25. The die and feed block were both maintained at about 300 ° C; The melting temperatures of the first and second extruders were about 285 ° C and 300 ° C, respectively. The temperature of the high-speed blowing air was maintained at a set point of about 400 ° C. The melt blown multilayer fibers thus formed were collected at a DCD of about 15 cm (distance from the die to the collector).

The webs of Examples 4 to 9 contained about 90 g / m2 Lt; RTI ID = 0.0 > 10 < / RTI > m in diameter.

Comparative Example

Comparative Example 1

No split feed block was used and the meltblown fibers were all comprised of a first polymer, particularly a poly (ethylene terephthalate) (PET; 0.54 intrinsic viscosity) resin obtained under the tradename N211 from Nanya Plastics Corporation of Livingston, Meltblown nonwoven web was prepared using substantially similar process conditions as in Example 1, except that the meltblown nonwoven web was a completely monolayer fabric made from the meltblown nonwoven web.

The extruder gear pump was adjusted so that the PET polymer melt was delivered at a throughput rate of about 0.175 kg / hr / cm die. Keeping the die at about 305 캜 and keeping the feed block at about 305 캜; The extruder melt temperature was maintained at about 305 占 폚. The air knife gap width of the blown air supply was about 0.76 mm; The temperature of the high-velocity inlet air was maintained at a set point of about 400 ° C and the pressure was suitable for producing a uniform web. The melt blown monolayer fibers thus formed were collected with a DCD of about 38 cm.

Comparative Example 2

All fibers are single layer fibers consisting of a second polymer, especially poly (butylene terephthalate) (PBT) obtained under the trade name Valox -195-1001 from SABIC Innovative Plastics, Fitzpatrick, MA Shrinkage data were obtained from the meltblown nonwoven web. No process conditions were obtained, but it was considered that conventional (single layer fiber) melt blown apparatus and process conditions were used. The heat shrinkage measurements reported for these materials were also obtained using heat shrinkage tests slightly different from those described above (see Chen et al., PCT Patent Application No. PCT / CN2014 / 080901, Case Number 75424WO003, melt blown THERMALLY STABLE NONWOVEN WEB COMPRISING MELTBLOWN BLENDED-POLYMER FIBERS WITH POLYMER FIBERS. For example, the sample was held at 170 占 폚 for 15 minutes rather than held at 180 占 폚 for 15 minutes. Thus, the shrinkage number of Comparative Example 2 may not exactly match other data; However, Comparative Example 2 is still useful for illustrating the general trends disclosed herein.

Heat shrinkage for various examples and comparative examples is reported in Table 1.

[Table 1]

Other Example

The above-described embodiments have been provided in accordance with available records, and have been provided merely for clarity of understanding; It should not be understood as an unnecessary limitation therefrom. The tests and test results described in the embodiments are intended to be illustrative rather than predictive, and variations of the test procedure may be expected to produce different results. All quantitative values of the embodiments are approximated in terms of generally known tolerances involved in the procedure used.

It will be apparent to those skilled in the art that the specific elements, structures, features, details, configurations, etc. disclosed in this specification may be modified and / or combined in numerous embodiments. It is contemplated by the inventor that all such modifications and combinations are within the scope of the inventive concept, not the exemplary design chosen to serve as an illustrative example only. Accordingly, the scope of the invention is not to be limited to the specific illustrative embodiments described herein, but rather extends to the arrangements described by the following claims and equivalents thereof. Any element that is explicitly referred to herein as an alternative may be expressly included in the claims or excluded from the claims in any combination as desired. Any element or combination of elements referred to herein in an open-ended language (e.g., comprise and derivations thereof) is defined as a closed-ended language (e.g., (such as consist and its derivatives) and a partially closed language (e.g., consisting essentially of and derivatives thereof). While various theories and possible mechanisms may be discussed herein, in any case such discussion does not limit the gist of the claimed invention. In the event of any conflicts or contradictions between the written specification of the present disclosure and the disclosure of any of the documents incorporated herein by reference, the written description herein shall prevail.

Claims (24)

A thermostable meltblown fiber web comprising a plurality of the melt-blown multilayered fiber, where at least selected meltblown multilayer fiber is at least one first layer consisting of the first polymer is a polymer which slowly crystallized with at least about 200 ℃ T _m in include, and at least one second layer consisting of a polymer of a second polymer which crystallized rapidly with about 200 or more ℃ T _m respectively, and
Said meltblown multi-layer fibers representing an average weight ratio of said first polymer to said second polymer of from about 45:55 to about 95: 05, said thermally stable melt blown fibrous web having a thermal stability Melt blown fibrous web. The method of claim 1 wherein the first polymer represents at least about 240 ℃ T _m, the second polymer is thermally stable meltblown fibrous web representing at least about 240 ℃ T _m. The heat stable melt blown fibrous web of claim 1, wherein the melt blown fibers exhibit an average weight ratio of the first polymer to the second polymer of from about 60:40 to about 90:10. The heat stable melt blown fibrous web of claim 1, wherein the melt blown fibers exhibit an average weight ratio of the first polymer to the second polymer of from about 70:30 to about 80:20. The method of claim 1, wherein the first polymer is selected from the group consisting of poly (ethylene terephthalate), poly (ethylene naphthalate), poly (lactic acid), poly (trimethylene terephthalate) Stability melt blown fibrous web. The heat stable melt blown fibrous web of claim 1, wherein said first polymer is poly (ethylene terephthalate). The heat stable melt blown fibrous web of claim 1, wherein the first polymer is substantially free of non-polymeric nucleating agents. The heat stable melt blown fibrous web of claim 1, wherein the second polymer is selected from the group consisting of poly (butylene terephthalate), polymethylpentene, and syndiotactic polystyrene. 2. The thermally stable melt blown fibrous web of claim 1, wherein said at least selected multi-layer fibers each comprise at least one pair of first layers sandwiched by a second layer therebetween. 2. The method of claim 1, wherein the at least selected multi-layered fiber comprises at least three first layers and at least two second layers, wherein each second layer comprises a plurality of heat- Stability melt blown fibrous web. 2. The method of claim 1, wherein the at least selected multi-layered fiber comprises at least five first layers and at least four second layers, wherein each second layer comprises a plurality of first heat- Stability melt blown fibrous web. The method of claim 1, wherein the at least selected multi-layer fibers each comprise at least n first layers and at least n-1 second layers, wherein n-2 or more of the second layers are individually Wherein n is a number from 7 to 51. The thermally stable melt blown fibrous web of claim < RTI ID = 0.0 > 1, < / RTI > The heat stable melt blown fibrous web of claim 1, wherein the first layer is a single component layer and the second layer is a single component layer. 2. The thermally stable melt blown fibrous web of claim 1, wherein the plurality of meltblown fibers collectively exhibit an average fiber diameter of less than about 10 占 퐉. 2. The thermally stable melt blown fibrous web of claim 1, wherein the web further comprises staple fibers, wherein the staple fibers comprise from about 5% to about 50% by weight of the total weight of the fibrous material of the web. The heat stable melt blown fibrous web of claim 1, wherein the web exhibits less than about 6% heat shrinkage. The heat stable melt blown fibrous web of claim 1, wherein the web exhibits less than about 2% heat shrinkage. The method of claim 1 wherein the thermally stable meltblown fibrous web of meltblown fibers of the web will include any polymeric material which is less than 200 ℃ T _m to about 5% by weight. The method of claim 1 wherein any of the polymeric material is thermally stable meltblown fibrous web is substantially free of having the meltblown fibers of the web is less than 200 ℃ T _m. An article comprising the heat stable melt blown fibrous web of claim 1, wherein the article is selected from the group consisting of adiabatic article, soundproof article, fluid filtration article, or a combination thereof. 21. The article of claim 20, wherein the article exhibits less than about 5% heat shrinkage. Extruding a molten multi-layer flow stream through an orifice of the melt blowing die to form a molten multi-layer filament;
Attenuating the melted multilayer filaments using a high velocity gas stream to form multilayer melt blown fibers; And
Collecting the multi-layer melt blown fibers as a fiber mass,
At least selected multi-layered melt of the collected lump of the fiber flow stream where the blown fibers are at least about 200 ℃ T _m a slow crystallizing polymer is melt the at least one or more first layers and about 200 ℃ consisting of one polymer having T It comprises the at least one second layer consisting of a polymer, the molten second polymer to crystallize rapidly with _m, respectively. 23. The method of claim 22, wherein the attenuated multilayer filaments form an airborne stream of multilayer meltblown fibers, the method comprising injecting an airborne stream of staple fibers into the airborne stream of the multi- Further comprising collecting intermingled multilayer meltblown fibers and staple fibers as a fiber agglomerate. 23. The method of claim 22, wherein the method further comprises joining together at least a portion of the fibers in the fiber agglomerate to form a heat-stable melt blown fibrous web.

Images