NON-WOVEN MATERIALS OF DURABLE MULTIPLE LAYERSBACKGROUND OF THE INVENTIONNon-woven fabrics have been used as or in absorbers, wipes, filters, protective fabrics as well as in numerous other end-use applications. With respect to the absorbers and / or cleaning wipes, the meltblown fiber fabrics have been used as saturated or pre-moistened wipers as described in U.S. Patent No. 4,775,582 to Win et al. Similarly, fabrics of dual texture meltblown fibers have been used as household or industrial cleaners as described in U.S. Patent No. 4,833,003 to Win et al. The fabrics of melt blown fibers provide a porous fine fiber structure having numerous small interstitial spaces through the fabric. Therefore, fiber fabrics blown with polyolefin melt have excellent absorbency and drainage characteristics for oil and, if treated, for aqueous and other liquids. As additional specific examples, fabrics of meltblown fibers have been used, either alone or in combination with other materials, in several other applications that require good absorbency such as, for example, for floor mats absorbent, the gables for the oil and so on. However, many industrial or "heavy-use" applications of such absorbers and wipes expose the non-woven fabric to significant scorching and / or compression forces. These and other forces acting on the absorbent can often result in peeling or fraying of the fabric. Just as an example, non-woven absorbers are often used for floor mats in work areas to absorb oil, grease and other similar substances that are spilled on the floor in the course of work. By absorbing grease and / or oil spilled on the floor it becomes less slippery for workers and therefore provides a safer work environment. In this regard, many absorbers may begin to fray, to develop stacking, delamination or otherwise to deteriorate upon exposure to such stringent treatments. When a fabric begins to wear or degrade, the fabric may experience a significant loss in its ability to absorb liquids. Additionally, the degradation of a fabric due to rigorous treatment is also not desirable from the point of view that generates lint or particle dropping. Still further, the degradation of the fabric may also not be desirable when used as a floor mat due to the separation of the layers, the fraying by the degradation may create an uneven surface.
It is known that non-woven fabrics having an outer layer of thick fibers that alter or otherwise improve the properties of the fabric. As an example, a cleaning cloth, which is abrasive enough to serve as a cleaning cleaning cloth without using aggregate abrasive materials, is described in U.S. Patent No. 4,659,609 to Lamers et al. Lamers describes a layered abrasive fabric that includes a backing layer and a meltblown abrasive layer intimately bonded together. With the meltblown abrasive layer it generally has a basis weight of about 5 to about 25 grams per square meter (g / m2) and is formed of fibers having an average fiber diameter of about 40 microns or more. As a further example, U.S. Patent No. 5,429,854 issued to Currie et al. Describes an absorbent composite material that includes a meltblown fiber fabric with impact loading and a nonwoven backing layer. Additionally, U.S. Patent No. 5,639,541 issued to Adam discloses an oil absorber having improved abrasion resistance and, in one aspect, Adam describes a fine melt blown fiber cloth having a layer of coarse fibers bonded to the same. The rough fibers have a larger fiber size than the fine meltblown fibers and provide increased abrasion resistance of the fabric. While providing a highly absorbent material with good resistance to abrasion, manyMany applications and uses still require greater resistance to abrasion and durability.
In addition to durability, in many cleaning or rubbing operations it is often desirable that the fabrics also have a non-abrasive surface and / or cover similar to the improved fabric. This is particularly desirable in many cleaning cloths used to clean or apply active agents to the skin or other sensitive surfaces. The abrasiveness of the fabric, and therefore the amount of skin irritation that results from the use of the cleaning cloth, can often be increased by the presence of lint, impact or other irregularities in the fabric as well as stiffness or stiffness. hardness of the fabric itself.
The durability of the non-woven fabrics can often be improved by increasing the bond between fibers such as by the addition of external abrasives or by thermally bonding the non-woven fabric. However, improved abrasion resistance can come with the cost of the total absorbency and fabric cover. Therefore, the ability to achieve improved durability and sacrifice other desirable attributes of the non-woven fabric has been difficult.> i ifflfÍÍÍÍ? RÍ »| itllrh? IÉÉILIi? N? ÍATMI í Tfii • r - *" * - * "-« »" > ---- - ^. ~ ^. * ** ^^ - * < a ¡¡¡¡¡FaH tr * rt SYNTHESIS OF THE INVENTIONThe aforementioned needs are achieved and the problems experienced by those skilled in the art overcome by the non-woven fabrics of the present invention comprise a first layer of meltblown fibers and a second layer of blown fibers with a second melt layer. the fibers comprise a blend of from 0% to about 95% by weight of a crystalline olefin polymer and from 100% to about 5% by weight of an amorphous olefin polymer. Additionally, the second fiber layer is autogenously bonded to the first fiber layer. In addition, the multi-layer non-woven fabric can have an abrasion resistance in excess of 250 cycles. Desirably, the amorphous polyolefin comprises between about 5% and about 50% of the fibers of the second layer. The amorphous polyolefin polymer may comprise polymers having a crystallinity below 20% and, as examples, may comprise one or more propylene homopolymers, ethylene-propylene copolymers, propylene-butene copolymers and / or other propylene copolymers of alpha-olefin. In one aspect, the amorphous polyolefin polymer comprises a polyolefin elastomer. In a further aspect, the first layer of fine fibers desirably which may have an average fiber diameter of less than 8 microns and the second fiber layer may comprise fibers having a substantially similar average diameter or, alternatively, fibers of anji ^ f1 ** ^ '- mafc aa greater average fiber diameter. The basis weight ratio of the first layer to the second layer may be about 1: 1 or, in a further aspect, may be about 2: 1 or more. Additionally, the fibers of the first layer desirably comprise a propylene polymer such as, for example, crystalline polypropylene. In addition, the fibers of the second layer desirably comprise a mixture of a crystalline propylene polymer and an amorphous propylene polymer.
In a further aspect of the invention, the durable multi-ply non-woven fabric composite is provided having a first layer of meltblown fibers and a second outermost layer of meltblown fibers autogenously bonded to the first layer and in wherein the multi-layer nonwoven composite material includes a tertiary material, such as particle and / or short fiber material, dispersed within at least one of the first and second layers. As examples, the tertiary material may comprise cellulosic and / or pulp fibers and are desirably dispersed throughout each of the multilayer nonwoven composite layers. The fibers of the second layer desirably comprise from 5% to 95% of an amorphous polyolefin and from 5% to 95% of a crystalline polyolefin. The fibers of the first layer desirably comprise a propylene polymer such as, for example, crystalline polypropylene. In addition, the fibers of the second layer desirably comprise a mixture of crystalline polypropyleneaMJ .. »ifa ^ aLit and an amorphous propylene polymer. In a particular embodiment, the amorphous polyolefin desirably comprises a propylene elastomer.
BRIEF DESCRIPTION OF THE DRAWINGSFigure 1 is a partially cut away elevated view of a section of a multi-layer melt blown fiber fabric of the present invention.
Fig. 2 is a schematic diagram of an exemplary apparatus forming blown fiber fabrics with multiple layer melting of the present invention.
Figure 3 is a cross-sectional side view of a section of a multi-layer melt blown fabric of the present invention.
Figure 4 is a schematic diagram of an exemplary apparatus for forming the multi-layer melt blown fiber composite of the present invention.
DEFINITIONSAs used herein, the term "comprising" is inclusive or open and does not exclude additional non-described elements, compositional components, and method steps.
As used herein the term "non-woven" fabric or fabric means a fabric having a structure of individual threads or fibers which are interlocked, but not in an identifiable manner as in a knitted or knitted fabric. Fabrics or non-woven fabrics have been formed by many processes such as, for example, melt blown processes, spin-linked processes, hydroentanglement, air laying, carded weaving processes, and so forth.
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 the mixtures and modifications thereof. Additionally, unless otherwise specifically limited, the term "polymer" includes all possible configurations of the molecule's space. These configurations include, but are not limited to, isotactic, syndiotactic and random symmetries.
As used here, in the term "machine address" or MD means the direction in which it is produced. The term "transverse machine direction" or CD means the direction generally perpendicular to the MD machine direction.
As used herein, and the term "liquid" refers to liquids generally regardless of the form and includes solutions, emulsions, suspensions and so on.
As used herein, the term "autogenous bonding" refers to the interfiber bonding between discrete portions and / or surfaces independently of mechanical fasteners or external additives such as latex adhesives, solders and the like.
DESCRIPTION OF PREFERRED INCORPORATIONSReferring to Figure 1, the non-woven fabric 10 comprises at least two layers including a first layer 12 of meltblown fibers and a second layer 14 of meltblown fibers. The first layer is desirably a relatively thick layer having numerous interstitial spaces through the tissue. When in use, the second layer 14 of the non-woven fabric 10 desirably faces wear or compaction force. For example, the second layer 14 of non-woven fabric 10 desirably faces when it is used as a floor mat or faces the surface on which it will act when used as a cleaning cloth or as a cleaning cloth.cleaning implement. The non-woven fabric is typically heoha in the shape of a sheet and stored in the form of a roll. The sheet material can then be cut to the desired dimensions and / or formed as needed. The absorbent and cleaning cloths are commonly cut into rectangular square sections. As an example only, floor mats are often cut into segments that have dimensions of approximately 45 centimeters by 45 centimeters or more. Additionally, cleaning cloths are commonly cut into segments that have dimensions of approximately 12 centimeters by 12 centimeters or more. The materials can be converted as desired and specifically made to meet the needs of the end user. As particular examples, the materials can be easily converted into floor mats such as those described in United States of America No. 4,609,580 issued to Rockett and others in pre-moistened hand-grip cleaning cloths such as those described in U.S. Patent No. 4,778,048 issued to Kaspar and others; the complete contents of the aforesaid references are incorporated herein by reference.
The multilayer nonwoven fabric, when evaluating the second exposed layer, desirably has a reciprocal abrasion resistance of at least 500 cycles and more desirably has a reciprocal abrasion resistancein excess of about 1000 and still more desirably has a reciprocal abrasion resistance in excess of about 1500 cycles. Moreover, the present invention provides a meltblown fiber non-woven fabric that exhibits excellent abrasion resistance without significantly degrading the strength and / or absorbency of the same. Therefore, when used as an absorbent material or a liquid supply material, the non-woven fabrics of the present invention can have an absorbent capacity for the oil of at least about 8 grams and desirably have an absorbent capacity. of about 11 grams, and still more desirably have an absorbent capacity of about 15 grams or more. Additionally, the absorbent material can have a specific capacity of at least about 8 grams of oil per gram of substrate and more desirably has a specific capacity of at least about 10 grams of oil per gram of substrate and still more desirably it has a specific capacity of at least about 12 grams of oil per gram of substrate. Additionally, the absorbent material also has the ability to retain the absorbed fluid. Still further, the absorbent material is reusable. In this aspect the absorbent material can be dried, such as with a compressive force (for example twisted drying) without disintegrating or substantially degrading it.
In a further aspect, when used as a cleaning cloth, the non-woven fabric can provide a durable material that also provides a more flexible sheet and / or a less weathable surface, for example a surface that is softer or smoother in the skin, compared with similar fabrics. Moreover, the improved covering and / or compliance of the multilayer nonwoven fabric can be provided while substantially maintaining the strength and integrity of the meltblown material.
The first layer 12 desirably comprises a nonwoven fabric of fine fibers having an average fiber diameter of less than about 7 micrometers and more desirably having an average fiber diameter between about 1 micrometer and about 6 micrometers. The first layer desirably has a basis weight of less than about 20 grams per square meter (g / m2) and more desirably has a basis weight between about 50 grams per square meter and about 500 grams per square meter. As examples of absorbent materials which can employ a first layer having a basis weight between about 150 grams per square meter and about 400 grams per square meter and the cleaning cloths employ a first layer having a basis weight between about 30 and of 80 grams per square meter. The first fiber layer can be made by various methods known in the art and desirably comprises a non-woven fabric of meltblown fibers. Themeltblown fibers are generally formed by extruding a molten thermoplastic material through a plurality of capillary vessels such as filaments or fused filaments into gas streams (eg air), usually hot, at high converging velocity which attenuate filaments of molten thermoplastic material to reduce its diameter. Then, in the puffed fibers, confusion can be transported by high velocity gas stream and deposited on a collection surface to form a randomly dispersed meltblown fabric. Meltblowing processes are described, for example, in US Pat. No. 3,849,241 issued to Butin et al.; U.S. Patent No. 4,100,324 issued to Anderson et al .; U.S. Patent No. 3,959,421 issued to Weber et al .; U.S. Patent No. 5,652,048 issued to Haynes et al .; and U.S. Patent No. 5,271,883 issued to Timmons et al. The fabrics of meltblown fibers have a high volume, such as those described in U.S. Patent No. 5,652,048 to Haynes and others are particularly well suited for use with the present invention. The complete contents of U.S. Patent No. 5,652,048 issued to Haynes et al. Is incorporated herein by reference. The first layer of fine fibers can be formed by a blown matrix with simple fusion or by consecutive banks of fiber matrices** .aa..fc¿ .I.blown by melting by depositing the fibers on a forming surface. In this aspect, as used herein and throughout the term "layer", unless otherwise reported, it is widely used and may comprise one or more sublayers of similar polymeric material.
Suitable thermoplastic polymers for forming the first layer of fine fibers include, but are not limited to, polyolefins (e.g., polypropylene and polyethylene), polycondensates (e.g., polyamides, polyesters, polycarbonates, and polymers). polyarylates), vinyl polymers, polyols, polydienes, polyurethanes, polyethers, polyacrylates, polycarbonates, polystyrenes, and so on. Suitable examples of polyolefins include, by way of example only, polyethylene, polypropylene, polybutene and copolymers and / or mixtures thereof. As examples, the fibers may comprise polymers of propylene and / or ethylene and the copolymers thereof and more particularly may comprise copolymers of ethylene and / or propylene with alpha olefins. Additional examples of suitable polymers for making fine fibers also include poly (l-pentene), poly (2-pentene), poly (3-methyl-l-pentene), poly (4-methyl-l- pentene), nylon, polybutylene, polyethylene terephthalate, polybutylene terephthalate, and so on. Additionally, thermoplastic elastomers are also suitable for use with the presentThe invention includes, for example, ethylene-propylene rubbers, styrenic block copolymers, copolyester elastomers, polyamide elastomers, and so forth. In a particular embodiment, the first layer of non-woven fabric comprises crystalline polymer fibers having a higher crystallinity of 20% and still more desirably a crystallinity of about 30% or more and still more desirably a crystallinity of about 50% or more. plus. In an exemplary embodiment, the fine fiber fabric may comprise an inelastic crystalline propylene polymer. The fibers of the second layer may comprise between 5% and 100% amorphous polyolefin. Desirably, however, the fibers comprise a compound or a mixture of two or more olefin polymers. The second layer comprises thermoplastic fibers comprising an amorphous polyolefin and / or a mixture of an amorphous polyolefin polymer with a second polyolefin. As used herein, "amorphous" polyolefins include those that have a crystallinity of less than 20%. desirably, the amorphous polyolefins have a crystallinity of less than about 10% and still more desirably or a crystallinity below about 7%. The amorphous polymer is desirably mixed with one or more other polyolefins such as those described herein above and, desirably, comprise an ethylene polymer (e.g., a low density polyethylene liner and / or a high density polyethylene) or a polymer of crystalline propylene. The amorphous polyolefin desirably comprises between about 5% and aroundof 95% of the polymer component of the fiber and more desirably comprises between about 10% and about 50% of the polymer component of the fiber. In a further aspect, when the second layer comprises larger amorphous polyolefin fibers they desirably comprise between about 5% and about 45% and even more desirably comprise between about 10% and 35% of the polymer component of the fiber. However, with respect to personal care wipes and many absorbent composite fabrics, the amorphous polyolefin desirably comprises between about 10% and about 95% by weight of the fiber and still more desirably comprises between about 10% and 50% by weight of the polymer component of the fiber.
Amorphous amorphous polyolefins include amorphous polyalphaolefins which may comprise, by way of example only, or one or more propylene homopolymers, ethylene-propylene copolymers, propylene-butene copolymers and copolymers of propylene with other alpha-olefins. Commercially available amorphous polyalphaolefin moieties include, by way of example only, the REXTAC family of amorphous polyolefins from Huntsman Corp. and the VESTOPLAST polymers from Creanova AKG. A particularly prefd copolymer comprises a copolymer of propylene and l-butene under the trademark designation REXTAC 2730. In a further aspect, the amorphous polyolefin can comprise an elastomer. In this regard, the amorphous olefin elastomers that are createdí *? m? * A? lHk ~ k,? t? *? .? . ~ ... a ^^ aü. ,, »,, ^ ..«, ^. ^ í. ^ .M ^^^^^^^^ -.? ^ ¡^^^ ¡^ ^ ^, ^ AÁA suitable for use with the present invention include those available from Huntsman Corporation ba or the brand name REXFLEX FLEXIBLE POLYOLEFINS. Additionally, additional amorphous polyolefins believed to be suitable for use in the present invention include the stereoblock polymers. The term "stereoblock polymer" refers to polymer materials with controlled regional or stereosequence tack to achieve the desired polymer crllinity. By controlling stereoregularity during polymerization, it is possible to achieve atactic-isotactic stereoblocks. Methods for forming polyolefin stereoblock polymers are known in the art and are described in the following articles: G. Coates and R. Waymouth, "Oscillating Stereo Control: A Strategy for Thermoplastic Elastomeric Polypropylene Synthesis" 267 Science 217 - 219 (January 1995; K.Wagener, "Oscillating Catal: A New Concept for Plastics" 267 Science 191 (January 1995) .The stereoblock polymers methods of their production are also described in the United States patent. No. 5,549,080 issued to Waymouth et al, and United States of America No. 5,208,304 to Waymouth, et al.The additional amorphous polyolefins believed to be suitable for use with the present invention are also described in the European Patent No. . 0475307B1, European Patent No. 0475306A1, United States of America Patent No. 3,954,697, United States of America Patent No. 3 , 679,775 and U.S. Patent No. 4,143,858.
The second nonwoven fabric layer may comprise fibers having an average size or denier substantially similar to that of the fibers comprising the first layer. Alternatively, the second layer of the non-woven fabric may comprise fibers having a significant number of longer fibers. As an example, the first layer may have an average fiber size of less than about 7 microns and the second layer may have an average fiber size in excess of about 15 microns. As additional examples, the fibers of the second layer may have an average fiber diameter between about 10 and about 35 microns and still more desirably an average fiber diameter between about 12 microns and about 25 microns. In one aspect of the invention, the second layer may comprise fibers having an average fiber size of at least 10 microns longer than those of the first layer. Additionally, the second layer desirably comprises a significant number of fibers in excess of about 20 microns and moreover can have a substantial number of fibers in excess of about 35 microns. In this aspect the second layer may comprise a relatively homogeneous collection of longer fibers or a mixture or mixture of fibers varying in thickness and / or shape. Additionally, longer fibers can be created[lA - aaSftt ...wherein the smaller individual fibers "make cord" or otherwise become joined lengthwise so as to collectively form longer fibers.
The second layer of melt blown fibers may have a basis weight similar to that of the first layer. However, the basis weight of the first layer is desirably greater than that of the second layer. The basis weight ratio of the first layer to the second layer is desirably about 2: 1 or more and as an example may be between about 4: 1 about 15: 1. In a further aspect, the second layer desirably has a basis weight of at least about 17 grams per square meter and more desirably has a basis weight between about 20 grams per square meter and about 68 grams per square meter, and even more desirably between about 34 grams per square meter and about 58 grams per square meter.
The second fiber layer can also be made by meltblowing processes and, desirably, the fibers are deposited directly on the first layer of the non-woven fabric in a semi-molten state such that the fibers are autogenously bonded to the first layer. When blown fibers with larger diameter melt are made, the conventional melt blowing equipment can also be used to produce such fibers by suitably balancing the polymer therethrough, the diameter of the die tip hole, the height of the formation (for example the distance from the tip of the die to the forming surface), the melting temperature and / or the air pressure pulled. As a specific example, and in reference to the meltblowing apparatus 20 described in FIG. 2, a first series of meltblowing banks 22 and 23 produces a substantially first homogeneous layer 24 on a forming wire 26 and the conditions of process or equipment comprising the last meltblowing bank 28 in a series of meltblown banks is adjusted such that 0 deposits a second layer 30 of larger fibers on the first newly formed layer of meltblown fibers. , and therefore forms multi-layer nonwoven 32. With respect to making longer polypropylene fibers, longer fibers can be achieved in conventional melt blowing machines by reducing the main air temperature and pressure thus how to lower the training height. The thickness or basis weight of the second layer can be increased as desired by increasing the number of consecutive melt blowing banks altered to provide such fibers. It is noted that the alteration of other parameters alone or in combination with the aforementioned parameters can also be used to create longer and / or thicker fibers. Methods for making longer meltblown fibers are described in greater detail in U.S. Patent No. 5,639,541 to Adam and U.S. Patent No. 4,659,609 to Lamers and others.; the complete contents ofeach of the aforementioned references are incorporated herein by reference. In a further aspect, it is possible to deposit more than one layer of long fibers in the first layer of fine fiber.
After deposition, the multiple layers may, optionally, be additionally joined together. Yes, however, an additional joint is desired it is preferred to employ a bonding pattern that is not more than about 15% of the surface area of the sheet. Desirably the bonded regions of the non-woven fabric comprise between about 0.5% and about 10% of the surface area of the fabric and still more desirably comprise between about 1% and about 5% of the surface area of the fabric . Using higher bonding areas can significantly reduce the absorbent capacity and / or significantly degrade the strength and / or the cover of the non-woven fabrics. The multilayer laminate may be joined by substantially continuous or continuous seams and / or discontinuous joined regions. Preferably in the multi-layer absorbent materials they are knitted. As used herein, "point union" or "point joining" refers to the joining of one or more layers of fabric at numerous, discrete, small junctions. For example, the thermal point joint generally involves passing one or more layers to be joined between heated rolls such as, for example, an engraved pattern roll and an anvil roll. The engraved roller has a pattern in some way for the complete fabricK? iaÍít ^ it3 ^? Uk? k? *. ^ .- ~. ^^?. ^? ^^! M¿í. _..___ "__.....? ^ JA? Í ^ ¡? ^^ m ^ MÍJÍ ^^ t¿i ^^ J? I ^ t ^» Hi ^ sA ^.it is not joined on the complete surface, and the anvil roller and that usually flat. Numerous patterns of union have been developed in order to achieve various aesthetic and / or functional attributes, the particular nature of the pattern is not considered critical to the present invention. Exemplary binding patterns are described in U.S. Patent No. 3,855,046 issued to Hansen et al., U.S. Patent No. 356,688 to Uitenbroek et al. And the U.S. Patent. of America No. 5,620,779 granted to Levy and others. These and other patterns of a joint can be modified as necessary to achieve the desired area and bonding frequency.
In a further aspect and with reference to Figure 3, a multilayer nonwoven sheet 40 is provided having a third layer 46 similar or identical in composition to the second layer 44 and which is coupled to the opposite side of the first layer 42. and therefore the first layer 42 of fine fibers is positioned between the second and third layers 44 and 46. The third layer desirably comprises fibers having a fiber size substantially similar to either those formed of the first or second layer. cap. In a particular embodiment, a highly foldable absorbent and / or cleaning cloth is provided having improved durability wherein the fibers of each of the first, second and third layers have an average fiber diameter of less than about 7 microns and , even more desirable, have a., it. ». au ....,. ^. fc ^. 1f, * t.i «tt A ..« m »J¿«., R____ », _ .. ... jt_, i..A jJAAntjil average fiber size less than about 5 micrometers. Non-woven fabrics can be made using conventional melt blowing equipment such that, when using a multiple bank system, at least the first and last bench extrudes amorphous polyolefin blends previously described herein. In an alternate embodiment of the invention, the second and third layers may comprise meltblown fiber fabric having an average fiber size greater than that of the first layer. In an exemplary embodiment, the first layer of fine fibers may comprise an inelastic propylene polymer having a crystallinity greater than 50% and the second and third layers of longer fibers may comprise a mixture of an amorphous propylene polymer and a polymer of inelastic propylene having a crystallinity greater than about 50%.
In still a further aspect of the invention, when the second layer comprises fibers having a diameter significantly greater than those of the first layer, a third layer can be included within the multilayer laminate wherein the third layer of fine fibers is deposited adjacent to the first layer of fine fibers and the second layer of longer fibers and further wherein the meltblown fibers of the third layer comprise a polymer composition similar and / or identical to that comprising the second layer. In this regard, when forming a non-woven multilayer fabric from a series of meltblowing banks, theL *. AA Á ^ A.h *? * L.second and last banks may use the same polymer composition as the meltblower bank to form the second layer wherein the process conditions and / or the equipment is adjusted to thereby form fine fibers similar to those of the first layer.
Additionally, one or more of the layers comprises the one multi-layer non-woven fabric optionally including particulate or fibrous material within the non-woven fabric. In this regard, melt blown fiber fabric composites can be incorporated into particulate or fibrous materials wherein by one or more processes known in the art. As an example, melt blown fiber composites can be formed using one or more "coform" processes. Suitable coform processes are described, by way of example only, in the commonly assigned U.S. Patent No. 4,818,464 to Lau; U.S. Patent No. 4,100,324 issued to Anderson et al .; and U.S. Patent No. 5,284,703 to Everhart et al. and U.S. Patent No. 5,350,624 to Georger et al .; whose complete contents of the mentioned references are incorporated herein by this mention. Generally speaking, coform materials may be made by a process in which one or more of the meltblown die heads are arranged near a conduit through which other materials are added to the fabric while the latter is added.
IAJAM, aA, fcÉ »A¿ is forming. Such other materials can be, for example, pulp, superabsorbent particles, cellulose and / or basic fibers. The fabrics of melt blown fibers incorporating such materials desirably contain between about 30% and about 85% by weight of the particulate or fibrous material and even more desirably contain between about 50% and about 75% by weight of the material in particles or fibrous. In many absorbent products, pulp and / or cellulosic fibers are particularly desirable because of their availability and at low cost. As a particular example of an absorbent material of the present invention, a multilayer nonwoven fabric comprising a first layer of crystalline propylene polymer fibers and a second layer of fibers comprising a mixture of amorphous propylene polymer and of crystalline propylene polymer wherein both layers contain cellulosic fibers and / or pulp dispersed therein.
Referring to Figure 4, the apparatus 50 can be used to make a highly foldable and absorbent multi-layer nonwoven fabric of the present invention. The shredder roller assembly 52 can be used to generate a stream of short fibers 54, eg, pulp, between the first and second convergent streams of the thermoplastic melt blown fibers 57 and 59. The first bank of blow matrices with melt 56 forms the first stream of blown fibers with melt 57 and~~ C? Ú.A. the second bank of meltblown matrices 58 forms the second stream of meltblown fibers 59. The first and second polymer compositions, as described herein, can be supplied to the first and second confusion blow matrices 56 and 58 respectively. The short fiber stream 54 is captured within the converging streams of thermoplastic polymer fibers thereby forming a composite material of blown fibers with multiple layers melting autogenously bonded 62 as the surface 60 is formed. The apparatus and the process for forming such structures Compositions are more fully described in U.S. Patent No. 5,350,624 issued to Georger et al. In an exemplary embodiment, a composite nonwoven material comprising between about 60 to 70% pulp is provided and wherein the first layer comprises a crystalline propylene polymer and the second layer comprises between about 50% and 90% a crystalline propylene polymer and between about 10% and 50% of an amorphous propylene polymer.
The multi-layer non-woven materials of the present invention may be used alone or as part of a laminated structure in combination with additional materials. In addition, the multilayer fabric of the present invention may, optionally, include various additives or chemicals applied topically in order to impart additional or improved characteristics to the non-woven fabric.
Such additives and / or treatments are known in the art and include, for example, alcohol repellency treatments, antistatic treatments, wetting chemicals (e.g., compositions that make a surface more hydrophilic, fire retardants, disinfectants). antibacterials, antifungals, germicides, virucides, detergents, cleaners and others Examples of suitable additives and / or topical treatments suitable for use with the present invention include, but are not limited to, those described in US Pat. of America No. 3,973,068 and 4,070,218 granted to Weber and others, 4,587,154 granted to Hotchkiss and others, 4,328,279 granted to Meitner and others, 5,696,191 granted to Nohr and others and 5,770,549 granted to Gross, In addition, the multi-layer material can be treated with the compositions described in commonly assigned United States of America patent application No. 09 / 320,324 on May 6, 1998 and 09 / 293,294 filed on April 16, 1999 to Yahiaoui et al., whose full contents of the aforementioned references are incorporated herein by this reference.
The addition of chemical treatments to the materials of the present invention can be accomplished by various methods known to those skilled in the art. Preferred methods apply the humidifying chemical substantially uniformly throughout the substrate. As examples, chemical treatments can be applied topically during or after tissue formation and / or internally added prior to extrusion. When added internally, a subsequent "blooming" step may be necessary in order to bring the chemistry to the surface of the fiber. A method for topically treating the porous material includes passing the absorbent web or sheet under an applicator, such as a spray dispenser bar, wherein an aqueous liquid containing the desired chemistry is applied or sprayed onto the porous substrate. A vacuum can, optionally, be placed under the porous substrate in order to help pull the aqueous liquid through the tissue and improve the uniformity of the treatment. Then the porous substrate, inside the aqueous liquid on it is dried. When the water is expelled, the desired chemical remains on or in the substrate. As a further example, the spray dispenser bars may be located on one side of each bank or series of meltblown matrices in order to spray the blowing fibers with the desired chemical prior to the formation of the meltblown fabric. the forming wire. The heat of the blown fibers causes water or other substrates to flash out. Additional methods for substrate treatment are also suitable for use with the present invention, such as, for example, "embedding and squeezing" processes, brush coating processes and others. The wetting agent or other chemical composition generally comprises from about 0.1% to about 10% of the total weight of the dried nonwoven fabric. However, the weightlm. & Ai & "Mikkste, i, aggregate of the particular chemist may vary outside these ranges depending on the function and the particular purpose of the same.
The multilayer nonwoven fabrics of the present invention can be used in a variety of materials and applications. But also as examples, the multi-layer non-woven fabrics of the present invention are well suited for use as wet and / or dry cleaning cloths (including personal, medical, industrial and / or residential uses), absorbent and absorbent materials, products for the delivery of liquid, protective fabrics and others. As a particular example, non-woven multilayer fabrics can be used on an absorbent floor mat. As a further example, non-woven multilayer fabrics can be used as a pre-moistened personal care cleaning cloth.
TESTSAbsorption Capacity: a sample of 4 inches by 4 inches is initially weighed. The heavy sample is then soaked in a test fluid tray (e.g., paraffin oil) for 3 minutes. The test fluid should be at least 2 inches (5.08 centimeters) deep in the tray. The sample is removed from the test fluid and allowed to drain whilehang in a "diamond" shaped position (for example, with a corner at the lowest point). The sample is allowed to drain for 5 minutes. After the assigned drain time, the sample is placed on a weighing plate and then weighed. The absorption capacity (g) = wet weight (g) - dry weight (g); and Specific Capacity (g / g) = Absorption Capacity (g) / dry weight (g).
Reciprocal Abrasion Test: The "reciprocal abrasion test (RAT)" involves caressing a sample, usually 140 millimeters by 180 millimeters of cloth with abrasive silicone rubber and after evaluating the fabric with respect to fraying, string formation and hairiness . The horizontally reciprocating dual head abrasion tester used here is model No. 8675 from United States Testing Company, Inc., of Hoboken, New Jersey. The fiberglass reinforced material of solid erode silicone rubber has a rubber surface hardness of 81 A durometers, a Shore A of 89 (± 9) is 914 millimeters by 102 millimeters by 0.127 millimeters thick and is available as Catalog No. 4050 of Flight Insulations, Inc.,(distributors for Connecticut Hard Rubber) of Marietta,Georgia. The abrasive must be conditioned by cycling it on a piece of waste material that is going to be tested 200 times. The test sample must be free of bends, creases, etc., mounted on the instrument on the cork backing with the second outer fiber layerítiA.si.á: ái * ~ MA -? .. i., o.
Face up and clean fibers from residual surfaces with a camel hair brush. The eroding arm should be lowered and the cycle should start at a total weight of 1180 grams with half the weight on each of the two eroding arms. Erosion cycling on the specimen is repeated until extensive fiber fraying and surface destruction is carried out.
Peeling test: In the peel or delamination test, a laminate is tested with respect to the amount of tension force that will pull and separate the laminate layers. The values for the peel strength are obtained using a specified fabric width, usually 102 millimeters, a clamp width and a constant extension rate. The sample is delaminated by hand by an amount sufficient to allow it to be caught in position. The specimen is grasped in, for example, an Instron apparatus, model TM, available from Instron Corporation, 2500 Washington Street, Canton, Massachusetts, 02021 or a Thwing-Albert INTELLECT II model, available from Thwing Albert Instrument Company, 10960 Dutton Road, of Philadelphia, Pennsylvania 19154, which has parallel clamps of 76 millimeters long. The sample is then pulled and separated at a 180 ° separation and the tensile strength recorded.
Cstability: The crystallinity can be determined through the use of an X-ray diffraction ofá? -Jt. __, __, JtlM! Lt A &? DA8? ~ To * Mm * j * Jb4i & tti * íMAU & Wide angle (WAXD). The percent crystallinity can be calculated with the following equation:percent C = (Ac / Aa + Ac)) x 100in which the percent C again represents the percent crystallinity, Ac represents the total area under the wide angle X-ray diffraction peaks and Aa + Ac represents the total area under the WAM pattern, Aa representing the peaks amorphousCup Crush: The softness of a non-woven fabric can be measured according to the "cup crush" test. The cup crush test evaluates the stiffness of the fabric by measuring the peak load or the "cup crush" required for a hemispherically shaped foot 4.5 centimeters in diameter to crush a piece of fabric 25 centimeters by 25 centimeters in one piece. inverted cup of approximately 6.5 centimeters in diameter by 6.5 centimeters in height with the cup-shaped cloth being surrounded by a cylinder with a diameter of approximately 6.5 centimeters to maintain a uniform deformation of the cup-shaped fabric. An average of 10 readings is used. The foot and cup are aligned to avoid contact between the walls of the cup and the foot which could affect the readings. The peak load is measured while the foot is lowering at a rate of 40.6 centimeters per minute and measured in grams. The cup crush test also gives a value for the total energy required to crush a sample (the "cup crush energy") which is the energy from the start of the test to the peak load point, for example, the area under the curve formed by the load in grams on one axis and the distance that moves to the foot in millimeters in the other. The cup crush energy is therefore reported in grams-millimeters. Lower cup crush values indicate a softer or more collapsible laminate. One suitable device for measuring cup crushing is a Sintech voltage tester and a 500 gram load cell using the TESTWORKS software all of which are available from Sintech, Inc., of Research Triangle, Park, North Carolina.
Stress Resistance: The tensile strength or peak load measures the maximum load (grams force) before the sample breaks. A 4-inch-by-6-inch sample is placed in jaws or a 1-inch by 1-inch rubber-coated clamp and in 1-inch-by-2-inch rubber-clamped jaws or clamp (with the longest dimension being perpendicular to load) so that the direction of the machine (for example, the direction in which the fabric is made is parallel with the load.) The sample is then placed on the jaws so that there is a length of 3 inches. can be carried out with an Instron 1130 voltage tester (available from Instron Corporation, Canton, Massachusetts) and uses a crosshead speed of 12 inches / minute and a load cell of 10 pounds. in grams.
EXAMPLESExample 1: A melt blown fiber fabric of 88 grams per square meter was made comprising a first layer of 47 grams per square meter of blowing with fine fiber melting and a second layer of 41 grams per square meter of melt blowing of longer fiber. Fine fiber melt blowing comprises a crystalline polypropylene, available from Himont USA, Inc., under the designation, Polypropylene PF015 and has an average fiber size of about 6 microns. The longest fiber meltblown comprised a blend of 65% by weight crystalline polypropylene, available from Himont USA, Inc., under the designation Polypropylene PF015 and 35% by weight amorphous polyalphaolefin, available from Hunstman Corporation, under the designation REXTAC 2730, and has an average fiber size of approximately 18 micrometers. The resulting meltblown fabric has an oil absorbency of about 8 grams, a specific capacity of 8.3 g / g, a peel strength of 93 grams and an abrasion resistance in excess of 1500 cycles (using a reciprocal abrasion test). ). Therefore a material is provided. ^ S? ÁiÉ? Absorbent that has both excellent absorbency as well as strength and durability.
Example 2: A melt blown fiber fabric of 88 grams per square meter was made comprising a first layer of 47 grams per square meter of blown with fine fiber melt and a second layer of 41 grams per square meter of melt blown of longer fiber. Fine fiber melt blowing comprises a crystalline polypropylene, available from Himont USA, Inc., under the designation Polypropylene PF015 and has an average fiber size of about 6 microns. The longest fiber meltblowing comprised a blend of 50% by weight crystalline polypropylene, available from Himont USA, Inc., under the designation Polypropylene PF015 and 50% by weight amorphous polyalphaolefin, available from Hunstman Corporation, under the designation REXTAC 2730, and has an average fiber size of approximately 20 micrometers. The resulting melt blown fabric had an oil absorbency of approximately 8 grams, a specific capacity of approximately 8 g / g, a peel strength of 108 grams and an abrasion resistance in excess of 1500 cycles(using a reciprocal abrasion test). Therefore an absorbent material is provided which has both excellent absorbency as well as strength and durability.
Example 3: A composite of blown fiber fabric with multi-layer melting of 75 grams per square meter was made using an angled dual bench melting blown apparatus and processes as described in the United States of America patent No. 5,350,624 granted to Georger and others. The first bank extruded thermoplastic polymer fibers comprising Polypropylene PF015 available from Himont USA, Inc., and the second bank extruded thermoplastic polymer fibers comprising an amorphous propylene polymer., FPO WL 120 available from Hunstman Corporation. The melt blown fiber composite comprised approximately 65% by weight of CF 405 pulp fibers available from Weyerhaueser Company. The multi-layer melt blown fiber composite had a tensile strength of 1250 grams in the machine direction and 1102 grams in the transverse direction to the machine. In addition, the multi-layer melt blowing compound had a cup crush value of 2872 (dry) and 1118 (wet, for example saturation of 300% by weight). In addition, the multi-layer melt blown fiber composite produced a lower transepidermal water loss (TEWL) on the users during extended and repeated use, eg, the resulting cleaning wipes caused less skin irritation and / or degradation of the barrier function of the skin. Therefore, a blown composite with multiple layers fusion was formed having a good strength and fall while also beingÍA ... í-á, ií.á! .i.a. i.i-. ^ .-. aaüaa & aa Áí ,. Í.U ..provided a cleaning cloth that has less abrasive properties.
Example 4: A first meltblown fiber fabric was formed according to U.S. Patent No. 5,811,178 issued to Adams et al., Comprising polypropylene fibers PF015 and had a basis weight of 390 grams per square meter . The first fabric of blown fibers with fusion was thermally knitted. A second layer of 34 grams per square meter was formed directly on the first melt blown fiber fabric and comprised 805 by weight, of polypropylene PF015 and 20%, by weight of an amorphous propylene elastomer FPO WL 121. The second layer was formed using an 8-inch forming height, an extrusion temperature of 380 ° F and with the primary air temperature from 380 ° F to 3 pounds per square inch. The second layer had fibers that have a larger diameter than that of the first layer. The multi-layer non-woven fabric was knitted together along the seams using a mechanical compaction pressure. The resulting multilayer laminate had excellent absorbency and abrasion resistance.
Example 5: A blown fiber web was formed with multiple layer fusion on line using a multiple bank meltblown system. A first layer of melt blown fibers was formed, according to the patentÍd * i,? A.É¡á..i * A * ¿...... a í¿é. *, ^ Í *.of the United States of America No. 5,811,178 granted to Adams and others, of polypropylene fibers PF015 and had a basis weight of 348 grams per square meter. The process conditions of the last bank were modified by reducing the forming height and cutting the primary air pressure by 50%, thereby providing a second layer of fibers having a relatively large diameter relative to the first layer. The second layer was formed on the first layer, had a basis weight of 42 grams per square meter and the fibers comprised 70%, by weight, polypropylene PFO 15 and 30%, by weight, of an amorphous propylene elastomer FPO WL 121 The resulting multilayer laminate exhibited excellent abrasion resistance and durability and also a volume of 0.17 inches and a specific absorbent capacity of 8.8 grams / gram.
Even though several patents and other reference materials have been incorporated herein by this mention, to the extent that there is inconsistency between the incorporated material and that of the written description, the written description will control. Furthermore, even though the invention has been described in detail with respect to the specific embodiments thereof, and particularly by the examples described herein, it will be apparent to those skilled in the art that various alterations, modifications and other changes can be made without disclosing them. of the spirit and scope of the present invention. Therefore, it is intended that such modifications, alterations and other changes be encompassed by the claims. h_ü.fe__ij.