MXPA01007567A - Hollow polymer fiber nonwoven web material - Google Patents

Abstract

A personal care absorbent article constructed of a hollow polymer fiber nonwoven material produced from a plurality of hollow polymer fibers and having a basis weight in the range of about 8 gsm to about 200 gsm. The hollow polymer fibers of this nonwoven web material have an outside diameter in the range of about 7 microns to about 50 microns. The hollow polymer fibers of this invention in accordance with one embodiment are made from a metallocene polypropylene resin.

Description

«¿¿¿- NON-WOVEN FABRIC MATERIAL OF HOLLOW POLYMER FIBER FIELD OF THE INVENTION The invention relates to non-woven materials to non-woven laminates, including laminated / woven laminates and more particularly to non-woven materials suitable for use in absorbent articles for personal care such as diapers, incontinence garments, underpants d learning, women's care products such as sanitary napkins or pads, and the like. More particularly, the invention relates to non-woven materials formed of hollow filaments and / or hollow fibers used in absorbent articles for personal care. 15 DESCRIPTION OF PREVIOUS ART Non-woven fabrics and laminates that comprise non-woven fabrics are widely used components of absorbent articles such as disposable diapers, women's hygiene products including sanitary pads or plugs, incontinence garments, disposable medical garments and the like, and much effort has been made to improve the effectiveness and functionality of this articles. These articles generally include a liquid absorbent material backed by a liquid impervious barrier sheet. To improve the sense of comfort, the absorbent material has a coating of a material which masks at least the surface facing the product body. The purpose of the cover or the forr material is to structurally aid in containing the absorbent material and to protect the user from direct contact with the moisture of a previously wetted absorbent material. The cover material is typically a relatively low base nonwoven fabric. Improved product performance has been obtained in these products through the incorporation of an emergence handling material placed between this cover material and the absorbent material. (See the patent of the United States of America No. 5,429,629). The emergence handling material is made of a nonwoven fabric material, which is thick, low density, and relatively high basis weight. The cover material must, therefore, be permeable to the liquid on the side of the product that is placed in control of the body, actively promote the immediate transfer of each liquid application or discharge through the material handling emergence and until the absorbent pad. It is also necessary that the emergement management material initially retain the liquid passed through the cover material and then floss the liquid to the absorbent material.

In order to meet these requirements, it is necessary that the surfaces of cover material and emergence handling material or the surface of the fibers forming said non-woven fabrics be first wetted by the liquid. The wettability of the fibers or non-woven fabrics thereof is known to be achieved by treating the surface thereof with surfactants. See, for example, U.S. Patent No. 4,403,032 Hartmann et al. And U.S. Patent No. 5,042,387 issued to Sch alz. Alternative methods for imparting wettability to such materials teach, for example, in U.S. Patent No. 5,456.98 to Hansen et al., In which a bicomponent fiber with permanent hydrophilic surface properties is provided by the incorporating a surfactant into the pod component and optionally including a hydrophilic copolymer in the sheath component. See also United States Patent No. 5,582,904 issued to Harrington which teaches incorporation into a cast-spun or forged composition containing polyolefin for the production of non-woven materials of a modifying composition comprising at least one M, M-amine of fatty acid of 10-22 polyalkoxylated carbons, inclusive of amine having a linear straight chain half of 12-20 carbons preferably 18 carbons corresponding to that found in oleic or stearic acid, and up to about 6 percent, including 0.1 percent-45 percent by weight of a modifier composition, of a 10-2 primary or secondary fatty acid amide, such as an esteriamide.

A characteristic of a linear material which affects the characteristics of fluid intake of material is the amount of hollow volume within the material. In particular by increasing the amount of hollow volume, the characteristics of fluid intake, this is the ability of linear material to start the fluid intake is improved. For non-woven liners, hollow volume, or pore size can typically be increased by increasing the denier fiber of the fibers that make up the lining material. However, increasing the fiber denier may result in an undesirable decrease in fiber softness.

For emergence management, it has been found that an effective material is characterized by one or more of the following qualities: (a) an elastic structure having a selected base weight; (b) an appropriate amount of total fiber surface area within the internal structure of material; (c) a balance of fiber surface areas which are humid and non-humid; and (d) an appropriate distribution of the fibers within the volumetric space defined by the emergence management material. More particularly, the emergence management material incorporates distinctive parameters which help characterize the capillary of the liquid and other characteristics thereof, whose parameter includes the total amount of fiber surface area per standard unit of material; the amount of wettable surface area of such fibers per standard unit of material; u total wettable surface area multiplied by the density parameter; and a total non-humid surface area multiplied by the density parameter.

One issue associated with the use of laminated non-woven fabric in absorbent articles for personal care is the ability to provide a combination of contradictory properties, such as pleasing aesthetics, (softness, flexibility and similar) and a strength and resistance to abrasion in a single fabric. For example, the yarn-bonded fabrics used in laminates are typically formed of 100 percent polypropylene filaments to reinforce the inner layers against excessive stresses and potential damage during use. The resulting laminate can be more durable and have an improved appearance. This can also minimize contamination of sterile surfaces and medical applications by preventing loose fibers from containing sterile environments.

SYNTHESIS OF THE INVENTION It is an object of the present invention to provide a non-woven fabric and a laminate for use in absorbent articles for personal care such as disposable diapers, women's hygiene products, incontinence garments, disposable medical garments and the like. .

It is an object of this invention to provide a liner for absorbent articles for personal care such as sanitary napkins, catamenial pads, incontinence garments, disposable diapers or underpants for infant care, adult care or the child's care. and similar.

It is another object of this invention to provide the lining material for absorbent articles for personal care which is capable of initiating fluid intake as a result of increased hollow volume as compared to conventional lining materials while reducing amount of polymer required to produce the fibers comprising the lining material compared to conventional liner materials having comparable hollow volumes.

It is yet another object of this invention to provide an emergence handling material which provides a desired fiber surface area by standard material bond using less than comparable emergence handling materials.

These and other objects of this invention are examined by an absorbent article for personal care comprising a hollow fiber nonwoven material having a basis weight in the range of about 8 grams per square meter (gsm) to about 200 grams per square meter whose hollow fibers have an outer diameter in the range d around 7 microns to around 50 microns. As used herein the term "hollow" is a volumetric value of the fiber referring to the volume occupied by the lumen of the fiber. E "hollow percentage" refers to the total volume part of a fiber occupied by the lumen. The lumen of the hollow fibers according to this invention comprises in the range of about 10 percent to about 60 percent by volume of the hollow fibers, more preferably about 20 percent to about 60 percent by volume of the hollow fibers and more preferably about 30 percent to about 6 percent by volume of said hollow fibers. According to a particularly preferred embodiment of this invention, the hollow fiber non-woven fabric material makes hollow fibers comprising a polypropylene metallocene. Hollow fibers comprising a metallocene polypropylene according to this invention have a hollow percentage in the range of about 30 to 50 percent higher than hollow fibers made with a standard polypropylene. According to a particularly preferred embodiment of this invention, the hollow fiber non-woven material is spunbonded.

Through a range of basis weights, the non-woven materials bonded with hollow yarn are stronger than non-woven materials bonded with solid round fiber yarn for at least about 30 percent with minor elongation. As measured by cup crush, the hollow spunbonded material may not be as smooth as bonded with round solid fiber yarn in some cases, per typically more porous and has a higher volume level. a comparable level of resistance to a basis weight of 17 grams per square meter of material bonded with solid round fiber yarn, the material bonded with hollow fiber yarn can be made at a basis weight of 12 grams per square meter. At these weights, the material bonded with hollow fiber yarn is softer and more porous than the material bonded with solid round fiber yarn. In addition, the higher volume results in an increased void volume for improved fluid handling, particularly suitable for lining material applications. The same low density / high capacity attributes of the hollow fiber bonded yarn material are also important for this applications.

The hollow fiber materials have an improved formation on round to solid fiber materials. Hollow fiber structures are naturally more efficient structures with respect to providing surface area fiber strength than round solid fiber structures per unit mass. The hollow fiber materials have a reduced mass compared to materials made of conventional solid round fiber of equal diameter. Therefore the hollow fiber fabrics can be provided having additional fiber per unit area at an equivalent basis weight in relation to fabrics comprising conventional solid fiber materials, or conversely, fabrics having a lower bas weight without lowering the number of fibers or filaments. This can improve the opacity, strength and / or barrier properties of the fabrics without unduly increasing the basis weight. This can also improve the resistance to bleeding through the adhesives and improve the containment of superabsorbent particles and the transfer / rewet for the hygiene applications due to the increased number of filaments and / or fibers for a given basis weight. In addition to increasing the strength, the reduced elongation of the hollow fibers to peak load breakage results in less material stretching and narrowing during the conversion of the product and comparison to nonwoven materials made with solid round fibers of corresponding diameter. In addition, at equivalent base weights, the materials bonded with hollow fiber yarn show very little deformation in the transverse direction and comparison to the materials bonded with solid round fiber yarn made of fibers of an equivalent fiber diameter. This attribute provides significant benefits in that the material deformation in the transverse direction causes conversion difficulties, for example conversion of diaper lamination of joined with yarn / film, etc.

As previously stated, the materials bonded with hollow fiber yarn according to this invention can be replaced by conventional solid base yarn-bonded materials at the existing basis weight to provide improved functionality or a reduced basis weight with essentially a functionality equivalent. A number of potential applications exists under any scenario. For example, materials bonded with hollow fiber yarn can provide improved opacity and coverage, increased barrier properties and improve strength for applications such as spunbond / meltblown / spin-bonded (MSM) materials for Care of the professional salu. In addition, bicomponent air-bonded and crimped bicomponent fibers can be used for high-performance surfacing materials. At lower base weights, hollow fiber materials being as strong, more porous, and softer as round and solid fiber materials have values such as linings, exterior covers incorporating fibrous layers or low cost surfacing materials for absorbent articles for personal care Although the invention claimed herein is generally described with respect to liner materials for use in absorbent articles for personal care, the non-woven materials constructed of hollow fibers as claimed herein may be used elsewhere in absorbent articles for the personal care, for example as a matter of emergence, and such other applications are considered as being within the scope of the claims. In addition the non-woven materials constructed of hollow fibers as claimed herein may be used in a variety of personal care absorbent articles such as disposable diapers, women's hygiene products, incontinent garments, disposable medical garments and the like and Such applications are considered to be within the claims.

BRIEF DESCRIPTION OF THE DRAWINGS These and other objects and features of this invention will be better understood from the following detailed description taken in conjunction with the drawings wherein: Figs. IA and IB schematically show representative spinner organ arrangements for spinning peripherally round filaments having a hollow (single concentric longitudinal lumen in which Fig. IA shows a vertical cross section through the spinning organ and Fig. IB shows a corresponding view of the face of the spinning organ where the melted filament streams emerge for the capillary arrangement shown in Figure IA.

DEFINITIONS As used herein the term "non-woven fabric" "non-woven material" means a material having a structure of individual fibers or threads which are embedded, but not in an identifiable manner as in a woven fabric. Fabrics or non-woven materials have been formed in many such processes, for example co-bonding processes, meltblowing processes, and bonded and bonded tissue processes. The basis weight of the non-woven fabrics and usually expressed in grams per square meter (gsm) and the fiber diameters are usually expressed in microns.

The term "machine direction" or "MD" as used herein refers to the direction of travel of the forming surface on which the fibers are deposited during the formation of a non-woven fabric.

The term "cross machine direction" or "CD" as used herein refers to the direction perpendicular to the machine direction.

As used herein, the term "spunbonded fibers" refers to small diameter fibers which are formed by extruding molten thermoplastic material with filaments of a plurality of usually circular and thin capillaries of a spinner with the diameter of the extruded filaments then being rapidly reduced as indicated, for example, in US Pat. Nos. 4,340,563 issued to Appel and others 3,692,618 issued to Dorschner et al., 3,802,317 issued to Matsuki and others, 3,338,992 and 3,341,394 granted to Kinney 3,502,763 granted to Hartmann and 3,542,615 granted to Dobo others. Yarn-bound fibers are generally not glued when they are deposited on the collector surface Spunbonded fibers are generally continuous and have average diameters (from a sample of at least 10) larger than 7 microns, more particularly from around 1 and 50 micras. The fibers may also have shapes such as those described in U.S. Patent No. 5,277,976 to Hogle et al., 5,466,410 issued Hills, and 5,069,970 and 5,057,368 to Largman et al. which describe hybrids with unconventional shapes. A non-woven fabric of spunbonded fibers produced by a cast yarn d is referred to as a "spunbonded".

As used herein, the term "" generally includes, but is not limited to, ovens, cos, such as block cos, graft, random and alternating, ters, etc. and mixtures and modifications thereof. In addition, unless otherwise specifically limited, the term "also includes all geometric configurations of the molecule, including, but not limited to, isotactic, atactic, syndiotactic, and random symmetries.

As used herein the term "monocomponent fiber" refers to a fiber formed from one or more extruders using only one. This does not mean that the fibers formed from one to which small amounts of adhesive have been added for coloring, antistatic properties, lubrication, hydrophilicity, etc. are excluded. These additives, for example titanium dioxide for coloring, are generally present in an amount of less than about d 5 percent by weight and more typically about about percent by weight.

As used herein, the term "bi-component fibers" refers to fibers which have formed at least two separate extrusion-extruded polymers separated together to form a fiber. The bicomponent fibers are also sometimes referred to as conjugated fibers or multicomponent fibers. The s are arranged in distinct zones placed constantly through the cross section of the bicomponent fibers that extend continuously along the length of the bicomponent fibers. The configuration of such bicomponent fiber can be, for example, a pod / core arrangement where u is surrounded by another, or it can be a side-by-side arrangement, a pie arrangement or an arrangement of islands in the sea. The bicomponent fibers are shown by the patents of the United States of America No. 5,108,820 granted to Kaneko and others, 4,795,668 granted Krueger and others, 5,540,992 granted to Marche and others and 5,336,552 granted to Strack and others. The bicomponent fibers are also shown by U.S. Patent No. 5,382,400 issued to Pike et al. And can be used to produce loops in the fibers by using differential expansion and contraction cups for two (or plus) . For the two component fibers, the s are desirably present in proportions of 75/25 to 25/75 or any other desired ratio and, as an example may be 50/50. The fibers formed of two or more segments thereof, such as polypropylene (PP) / PP fiber, as discussed elsewhere in this description, are considered to be monocomponent fibers.

As used herein, "thermal spot bonding involves passing a fabric or fabric of fibers that are to be bonded between a heated calender roll and an anvil roll." The calender roll usually has, but does not always, a pattern. in some way so that the complete fabric is not bonded through its entire surface.As a result of this, several patterns have been developed for calendering rolls for functional reasons as well as aesthetics. it varies from about 5 percent to about 30 percent of fabric laminate fabric area As is well known in the art, the point bond retains the layers laminated together as well as the one imparting integrity to each individual layer by and joining the filaments and / or fibers within each layer.The exemplary bond patterns are taught in the patents of the United States of America Nos. 3,855,046 granted to Hansen others, 5,620,779 grants gives to Levy and others, and Uitenbroek granted design patent of the United States of America No. 356,688, all of which are incorporated herein by reference As used herein, "air-bonding (" ") is a process of joining a non-woven bicomponent fiber fabric in which sufficient warm air to melt one of the s into the fibers of the fabric is forced to The air velocity is between 100 and 500 feet per minute and the dwell time can be as long as 6 seconds.The melting and resolidification of the joint ratio.The union through air has a variability relatively restricted and since the union through air requires the melting of at least one component to elaborate the union, it is very effective when applied to fabrics with do components such as conjugated fibers or those that include adhesive. through air, the air stops a temperature above the melting temperature of one component and below the melting temperature of the other component e directed from a surrounding cover, through the fabric, to a perforated roller that supports the fabric. Alternatively, the through air can be a flat arrangement where the air is directed vertically downwards on the tissue. The operating conditions of the two configurations are similar, the primary difference making the geometry of the fabric during joining. The hot air derives the lower melting component and thus forms bonds between the filaments to integrate the fabric.

DESCRIPTION OF PREFERRED INCORPORATIONS The material of this invention is a hollow fiber nonwoven fabric material having a basis weight in the range of about 8 grams per square meter to about 200 grams per square meter, the hollow fibers which have a diameter outside in the range of about 7 miera to about 50 microns, more preferably from about 1 to about 30 microns. According to a particularly preferred embodiment, the base weight of the hollow fiber woven fabric material is in the range of about 1 gram per square meter to about 30 grams per square meter. The material of this invention is suitable for use in absorbent articles for personal care such as diapers, underpants, adult incontinence garments, women's care products, disposable medical garments and the like. According to a particularly preferred embodiment of this invention, the material is used as a liner for such absorbent articles for personal care.

Hollow fibers suitable for use in the material of this invention are formed using conventional melt technologies, and preferably a spinning process. Many of the aesthetic and physical attributes of material formed from such hollow fibers are essentially the same as those of a solid fiber having an equivalent diameter. However, the material of this invention has a lower mass and a base weight provided to the hollow center and comparison to the materials formed by solid fibers. Those suitable for use in the manufacture of such hollow fibers include any which are suitable for producing fibers, but are limited to those currently used in connection with absorbent articles for personal care. Such polymer include, but are not limited to, metallocene, polypropylene (PP) polyethylene, nylon, polyester, and combinations thereof. Preferred polymers are those produced using metallocene catálisi. Particularly preferred is metallocene polypropylene (mPP).

In order to produce hollow fibers for the hollow nonwoven fabric material of this invention, a standard unitary spin pack is used in conjunction with a hollow spinning organ (Figures IA and Figure IB). Each orifice d of the spinning organ 10 (FIG. IA) consists of at least arched, slotted and equally spaced segments 11 (FIG. IB). Each spinner organ orifice preferably consists of but not limited to two, three or four slotted arcuate segments equally spaced apart. The polymer is extruded through the slotted arched segments to a desired production cup. By leaving the polymer each grooved arcuate segment it becomes attached to the arcuate segment grooved closer, but do not come together in the center, leaving a hollow nucleus (lumen) The resulting fiber has the same relative aesthetic appearance as a solid fiber of the same diameter. But it has a reduced mass.

According to a preferred embodiment of this invention, the hollow fibers are bicomponent monocomponent fibers comprising at least two segments. An example of the monocomponent hollow fiber suitable for use in non-woven materials according to an embodiment of this invention is a metallocene polypropylene (mPP) / mPP fiber. Examples of bicomponent hollow fibers suitable for use in the non-woven materials according to this invention, whose hollow fibers typically have a larger hollow portion than the fibers produced with the Ziegler-Natta polypropylene resins, include cos d PP / mPP, PP / ethylene propylene side by side (for example 6 43, an available Union Carbide copolymer which comprises 3 percent ethylene) and propylene butylene plus PP / P (for example DS4D05, a polypropylene 14 percent copolymer available from Shell Chemical Company). In order to produce bicomponent fiber formed and segmented essentially perfect, the polymer temperatures must be adjusted during spinning to achieve a viscosity that equals both polymers.

The s produced using metallocene catalysts have a narrow molecular weight distribution. The phrase "narrow molecular weight distribution polymer" refers to one that exhibits a molecular weight distribution of less than about 3.5. As is known in the art, the molecular weight distribution of a is the ratio of the average molecular weight of the weight of the polymer to a molecular weight by the number of the polymer. The methods for determining the molecular weight distribution are described in the Encyclopedie of Engineering and Science, volume 3, pages 299-30 (1985). Examples of the narrow molecular weight distribution polyolefins include the metallocene-catalyzed polyolefins, the single-site catalyzed polyolefins, and the constrained geometry-catalyzed polyolefins described above. As is known in the art, metallocene-catalyzed polyolefins and constricted geometrically-catalyzed polyolefins are sometimes referred to as single-site catalyzed polymers. The polydispersities (MW / MN) d below 3.5 and to one below the 2 are possible for the polymer produced with metallocene. Co-metallocene-produced polymers having a polydispersity below of about 3.0 are desirable and down to about 2.5 are more desirable. These s also have a narrow short chain branching distribution when compared to those produced in a similar manner by the Ziegler-Naffta.

Metallocene catalysts include bis (n-butylcyclopentadienyl) titanium dichloride, bis (n but i 1 cy 1 opent ad i in i) dic 1 or zirconium bis (cyc 1 op in tadi in i 1 o) - c 1 or ur of scandium bis (indenyl) zirconium dichloride, bis (methylcyclopentadienyl) titanium dichloride, bis (methylcyclopentadienyl) dichloride d zirconium, cobaltocene, cyclopentadienyl titanium ferrocene trichloride, hafnocene dichloride, isopropyl-cyclopentadienyl jl-flouroenyl) dichloride zirconium, molidocene dichloride, niquelocene, niobocene dichloride, ruthenocene, dichloride d-titanocene, hybrid zirconocene chloride, dichloride d zirconocene, among others. A more exhaustive list of such compounds is included in U.S. Patent No. 5,374,696 issued to Rosen et al. And assigned to the Do Chemical Company, such compounds are also discussed in the United States of America patent. No. 5,064,802 awarded to Stevens and others and also assigned to Dow.

The metallocene process, and particularly catalysts and catalyst support systems are the subject of numerous patents. U.S. Patent No. 4,542,199 to Kaminsky et al. Describes a process wherein a metallocene catalyst of the general formul (cyclopentadienyl) 2MeRHal wherein Me is a transition metal, Hal is halogen and R is Cyclopentadienyl or a C 1 to C 6 alkyl radical or a halogen, is used to form polyethylene. U.S. Patent No. 5,189,192 issued to La Pointe et al. And assigned to Dow Chemica discloses a process for preparing addition polymerization catalysts through metal center oxidation. U.S. Patent No. 5,352,749 issued to Exxon Chemical Patents, Inc., describes a method for polymerizing monomers in fluidized beds. U.S. Patent No. 5,352,749 to Exxon Chemica Patents, Inc. discloses a method for polymerizing fluidized bed monomers. U.S. Patent No. 5,349,100 discloses chiral metallocene compounds and their preparation by creating a chiral centriole by an enantrioselective hybrid transfer.

Co-catalysts are materials such as methylaluminosilane (MAO) which is the most common, other compounds containing alkyl aluminum and boron com tris (pentaflourophenyl) boron, lithium tetrakis (pentaflourofeino) boron, and dimethyl anilinene tetrakis (pentaflourephenyl) boron. The research is continuing on other co catalytic systems or the possibility of minimizing or eliminating alkylaluminum due to the issues of product contamination and handling. The important point is that the metallocene catalyst is activated or ionized to a cationic form for the reaction with the monomers to be polymerized.

As previously indicated the non-woven material of this invention has a basis weight in a range of about 8 grams per square meter about 200 grams per square meter, and the hollow polymer fibers used to form the non-woven fabric have an outer diameter in the range of about 7 microns to about 50 microns. It will often be more desirable to produce a hollow polymer fiber having as large a volume of lumen as possible. It will be apparent to those skilled in the art that there are certain limitations due to physical exceptions which limit the volume of the lumen within the hollow polymer fiber. According to a preferred invention of this invention, the lumen of the hollow polymer fiber comprises in the range of about 10 percent to about 60 percent by volume of the hollow polymer fibers. According to a particularly preferred embodiment, the lumen comprises in the range of about 30 percent to about 60 percent by volume of the hollow polymer fibers.

The nonwoven fabric materials made of hollow polymer fiber according to this invention are suitable for use as a liquid distribution layer and / or emergence handling material in articles for personal care, whose use requires that the material be able to handle multiple downloads.

The materials produced using the hollow polymer fibers according to this invention can be subjected to treatment which provide the fibers with desired characteristics for a particular application. For example, hollow polymer fibers produced from polypropylene can be made hydrophilic by the treatment with any number of surfactants known to those skilled in the art.

Nonwoven materials comprising hollow polymer fibers according to this invention often require being bound in order to provide integrity to tissue, and optionally further bonded to provide added strength, depending on the application. For non-woven materials comprising hollow fibers of polypropylene, thermal bonding is preferred. The non-woven materials used by the bicomponent fibers according to this invention can be joined either by thermal bonding or by an air-binding.

The following examples provide comparison between the spunbonded materials made of solid round fibers and the spunbonded materials made of hollow polymer fibers of equivalent diameter according to this invention. Each material analysis included an evaluation of five samples. The average value for each material is represented in the tables given below. The data collected for each material included the following: Grip tension: Peak load in the transverse direction (CD) Peak load in the machine direction (MD) Cup crush: Energy (gm / mm) under load (gm) Volume (inches) (thickness) a load of 0.05 pounds per square inch over atmospheric pressure Air permeability (cfm / sf) Hydrohead (mbarras) Opacity (%) The maximum loads in the transverse direction in the direction of the machine are a measure of the resistance of the material that is being evaluated; As such, the higher the peak load values, the stronger the material. E cup crushing, as previously indicated, is a measurement of the softness of the material being evaluated. In this case, the lowest cup crush values correspond to softer materials. Although it will be evident that with regard to fluid intake, the volume of superior material is typically desirable, the values for the hydro head, (resistance to fluid flow), air permeability and opacity are of primary significance in relation to the application of the material.

EXAMPLE 1 In order to compare the materials of the same resistance, a non-woven material comprising rounded joined fibers and having a basis weight of about 1 gram per square meter was selected. The fabrics of fibers bonded with yarns used in these examples were thermally bonded. The equivalent basis weight for non-woven material comprising yarn-bound fibers was determined to be about 12 grams per square meter. As shown in Table 1, the diameter of fibr for the fibers bonded with round and solid yarn was 14 microns while the fiber diameter for the fibers bonded with hollow yarn was 16.5 microns. The fiber denier was the same for both the fibers bound with rounded yarn and the fibers joined with hollow yarn. Although the n-woven materials made of hollow spunbonded fibers according to this invention have an essentially lower basis weight than the non-woven materials made of round solid fibers of equivalent diameter, the data showed that the charges in the direction Transverse and in the direction of the machine for both materials are the same. The data further showed that the hollow fiber material has an air permeability almost twice that of solid fiber material and a volume 5 percent greater than the volume of solid fiber material. The data also showed that the hollow fiber material is softer than the round solid fiber material based on the results of the cup crush test.

TABLE 1 EXAMPLE 2 Table 2 sets forth the results of a comparison of a non-woven material comprising fibers bonded with round and solid yarn and having a basis weight d about 17 grams per square meter with a woven material comprising fibers joined with hollow yarn and having the same basis weight, for example 17 grams per square meter and its non-woven material comprising fibers joined with hollow yarn having a basis weight of 14 grams per square meter. The respective fiber diameters were the same as in Example 1. As between the two nonwoven materials of basis weight 1 gram per square meter of this example, the peak loads in the transverse direction and in the machine direction for the material of hollow fibers were superior to those of solid round fiber material. The air permeability for the hollow fiber material was higher than for the solid round fiber material-620 cfm / sf against 557 cfm / sf. The maximum loads in the cross direction and in the machine direction for the base weight material of 14 grams per square meter are comparable to the peak loads in the transverse direction and in the machine direction for the round solid fiber material of 17 grams per square meter and the air permeability is substantially higher than for solid round fiber material. TABLE 2 EXAMPLE 3 A material bonded with solid round fiber yarn and a material bonded with hollow fiber yarn produced d fibers having a fiber diameter of about 24. microns and having a basis weight of 173 grams per square meter and a density of material or cloth 0.016 grams per cubic centimeter were prepared and subjected to simulation tests of multiple discharges. As shown in Table 3, the hollow polymer fiber material is capable of containing more fluid after each discharge than the solid fiber material, demonstrating the improved fluid handling properties of material bonded with hollow fiber yarn over the fibers. materiale joined with conventional solid fiber yarn.

TABLE 3 As previously stated, hollow polymer fibers comprising metallocene polypropylene polymer according to this invention typically have a hollow percentage in the range of about 30 to 50 percent higher than hollow fibers made with standard polypropylene (Ziegler). Natta).

EXAMPLE 4 In this example, the hollow fibers produced using a standard polypropylene polymer (Montel E5D47 P available from Union Carbide) were compared to the hollow fibers produced using a metallocene polypropylene polymer (Exxon 3854 Met PP available from Exxon Chemicals). The results indicate that, for the comparable outer diameter (OD) fibers produced under the same conditions, the hollow percentages of the hollow metallocene polypropylene fibers are greater than the hollow percentage of the standard polypropylene hollow fibers, in per l minus one case for more than 60 percent. As shown in Table 4, the gap percentage of the polypropylene metallocene fibers was higher in each case than the percentage of gap for the corresponding standard polypropylene fibers.

TABLE 4 Montel 1 E5D47 PP Exxon 38545 Met PP Pressure Diameter Hollow Diameter Denier Gap Denier d < = (MRritrai) Fibra Fibra dßFibra Multiple (g / 9000m) (Mieras) (g / 9000m%%) I.D. I.D. I.D. I.D. 430 degrees 0.75 gh 0.75 ghm Farenheith Melting temperature 4 14.7 28.9 26.0 5.2 18.0 29.6 37.1 5.5 16.6 16.6 34.6 5.0 16.6 27.2 37.1 4.6 6 16.7 26.7 39.0 4.5 7 12.7 24.2 27.4 3.7 8 12.1 23.6 26.3 3.5 9 12.2 22.7 28.9 3.2 450 degrees 0.75 ghm 0.75 ghm Farenheith Melting temperature 4 12.6 25.9 23.7 4.2 16.9 27.7 37.3 4.8 11.0 23.5 21.9 3.5 14.8 24.8 35.7 3.9 6 11.3 22.5 25.2 3.2 15.9 27.1 34.1 4.6 50 degrees 14.2 28.7 24.4 5.2 17.2 30.0 33.1 5.6 Farenheith 13.1 26.9 23.9 4.5 16.1 26.6 36.7 4.5 Temperature of 13.8 26.3 27.6 4.3 15.2 25.9 34.7 4.2 fusion 11.5 23.7 23.3 3.5 11.2 22.6 24.6 3.2 EXAMPLE 5 In this example, hollow polymer fibers of propylene ethylene copolymer (6D43 available from Unio Carbide) / bicomponent polypropylene (PP) according to an embodiment of this invention were produced and evaluated as an alternative to hollow polypropylene Ziegler fibers. -Natta under the same process conditions and spinning plate geometry. For the fibers produced at a melt temperature of 450 ° F and a manifold pressure of 9 pounds per square inch under atmospheric pressure, the hollow percentage of the hollow polymer fibers of propylene ethylene copolymer / bicomponent PP was consistently higher than e of standard Ziegler-Natt polypropylene hollow polymer fibers. For example, at one gram per hole per minute (ghm) in the range of 0.7 to 0.9, the hole percentage for hollow polymer bicomponent ethylene propylene / PP copolymer fibers ranged from about 16 to 17. hollow porcient compared to a range of about 9 to about 12 percent hollow for Ziegler-Natta standard polypropylene hollow polymer fibers. For the PP / propylene butylene bicomponent copolymer (DS4D05 available from Shel Chemical Company) the hollow polymer fibers produced under the same conditions, at a ghm of 0.9, the hue percentage of the fibers was about 17 percent.

TEST PROCEDURES CRUSHING CUP The softness of a non-woven fabric was measured according to the "Cup Crush" test. The cup crush test evaluates the stiffness of the fabric by measuring the peak load or "cup crush" required for a spherically shaped foot of 4.5 centimeters diametr to crush a piece of such 25 centimeters by 25 centimeters shaped into a inverted cup of 6.5 centimeters in height while the cup-shaped fabric is surrounded by a cylinder with a diameter of approximately 6.5 cm to maintain a uniform deformation of the fabric in the form of a cup. 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 that could affect the readings. The peak load is measured while the skin is descending at a rate of 40. centimeters / minute and measured in grams. The cup crush test gave a value for the total energy required to crush a sample ("cup crush energy") which is the energy from the start of the test to the peak charge point, for example the area under the curve formed by the load in grams on an axis and the distance that travels to the foot and millimeters on the other. The crushing energy d cup is therefore reported in grams-millimeters. The lower cup crush values indicate a softer lamination. A suitable device for measuring cup crush is a Sintech voltage provider and a 500 gram load cell using the TESTWORKS software all of which is available from Sintech Inc. of Research Triangle, Park, North Carolina.

HYDROSTATIC PRESSURE TEST (Hydrohead) A measure of the liquid barrier properties of a cloth is the hydro head test. The hydro head test determines the height of water or the amount of pressure of water (in millibars) that the fabric will support before it passes through and liquid through it. A cloth with a higher hydrohead reading indicates that it has a better barrier to liquid penetration than a cloth with a lower hydro head. The hydrohead data cited here was obtained according to the general test standard 19IA, Method 5514 except as modified as noted below. Hydrohead was determined using a hydrostatic head tester available from Mar Enterprises, Inc. of Concord, North Carolina. The specimen is subjected to a standardized water pressure, increasing a constant cup until the first sign of filtering appears on the surface of the fabric in three separate areas. (And filtered at the edge, aside from the lugs is ignored) unsupported materials, such as thin film or non-woven, are supported to prevent premature rupture of the sample.

RESISTANCE TO TENSION 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 a 1-inch-per-inch rubber-coated jaw or grab and jaws or 2-inch-inch rubber tire grab (with the longest dimension perpendicular to the load) so that the direction of the machine for example the direction in which the fabric is made and parallel with the load. The sample is placed on the jaws so that there is a length of 3 inches of measurement. The test can be carried out with an Instron 113 voltage tester (available from Instron Corporation of Canton MA) and uses a crosshead speed of 12 inches per minute. The charge to rupture is reported in pounds. The peak voltage is the percentage of elongation at the peak load.

AIR PERMEABILITY This test determines the rate of air flow through a specimen for a set pressure area size. The higher the air flow rate for a given area and pressure, the more open the material is, allowing more fluid to pass through it. The air permeability was determined using a pressure of 125 Pa (0. inches of water column) and was reported in a cubic foot per minute per square foot. The air permeability data reported here can be obtained using the TEXTEST FX 3300 air permeability tester.

BASE WEIGHT The basis weight of a non-woven material is determined by measuring the mass of a sample of a non-woven fabric, and dividing it by the area covered by the sample.

PROOF OF DISCHARGE SIMULATION The multiple discharge simulation test (MIST) measures the amount of liquid (salt water solution) that is maintained in a material when a specified volume of liquid is applied to the material under specified conditions was used to evaluate the materials of this invention. It also measures the amount of liquid retained in the material after the insulted material which liquid is placed in contact with an absorbent material, thereby allowing the liquid to be transferred from the test material to the absorbent material. The test procedure involves calibrating a pump to deliver 80 grams of liquid in 4 seconds (average flow rate of 20 grams per second). A liquid collection tray is placed on a laboratory scale from under the slit at the bottom of a non-segmented specimen container in the form of a cradle, the balance is then removed by tare. The specimen that is to be evaluated 2.5 inches wide by 7 inches long is placed on the bottom of the crib on a 2.5 inch wide part of the slit that is tapered to prevent the liquid from passing through this part of the body. the slit directly below the specimen. The slit at the bottom of the cradle runs through the center of the specimen in the direction of the sample width. The ends of the sample, the longest dimension are raised above the center of the sample at approximately 60 degrees horizontal. The sample is discharged by dispensing 8 grams of the liquid at a rate of 20 grams per second directed vertically downwards in the center of the specimen from the end of a fluid application bar maintained about 0.5 inches above the center of the sample. The liquid sample in the collection tray is recorded and the tare is removed from the balance. The specimen is then removed placed on an absorbent material covered with tissue. The absorbent material is composed of a mixture of 60 porcient of Favor® 870 superabsorbent available from Stockhausen GmbH and 4 percent of wood pulp at a total weight of 500 grams per square meter. A plate of 397 grams of 2.5 inches per inch / weight was placed on top of the specimen to cover the entire area of the sample for five minutes. This procedure is then repeated two additional times. The last two specimens for each material are tested. The liquid maintained for each discharge divided by the weight starts from the dry specimen and the liquid retained after each desorption was divided by the initial weight of the dry sample, then calculated.

Even though the foregoing description of the invention has been made in relation to certain preferred embodiments thereof and many details have been established for purposes of illustration, it will be apparent to those skilled in the art that the invention is susceptible to additions and that Certain of the details written here can be varied considerably without departing from the basic principles of the invention.

Claims (37)

r- '40 R E I V I N D I C A C I O N S

1. An article for the absorbent person care that includes: a hollow polymer nonwoven material comprising a plurality of hollow metallocene polymer fibers and having a basis weight in the range of about grams per square meter to about 200 grams per meter 10 square, said hollow polymer fibers have an outer diameter in a range of about 7 microns to about 5 microns.

2. An absorbent article for the city Personnel as claimed in clause 1 characterized in that said basis weight of said hollow polymer fiber nonwoven material is in the range of about 10 grams per square meter to about 30 grams per square meter.

3. An absorbent article for personal care as claimed in clause 1 characterized in that said hollow polymer fibers are one-component, bicomponent fibers comprising at least two segments. 25

4. An absorbent article for personal care as claimed in clause 1 characterized in that said hollow polymer fibers comprise at least one polymer having a molecular weight distribution of less than about 3.5.

5. An absorbent article for personal care as claimed in clause 1 characterized in that said hollow polymer fibers comprise at least one polymer having a polydispersity of less than about d 3.5.

6. An absorbent article for personal care as claimed in clause 1 characterized in that said hollow polymer fibers comprise at least one polymer having a polydispersity of less than about d 3.

7. An absorbent article for personal care as claimed in clause 1 characterized in that said hollow polymer fibers comprise at least one polymer having a polydispersity of less than about d 2.5.

8. An absorbent article for personal care as claimed in clause 1 characterized by '42 because said metallocene polymer is metallocene polypropylene.

9. An absorbent article for personal care as claimed in clause 1 characterized in that said nonwoven hollow polymer fiber material is laminated.

10. An absorbent article for personal care as claimed in clause 1 characterized in that said hollow polymer fibers are bonded.

11. An absorbent article for personal care as claimed in clause 1 characterized 15 because said hollow polymer fiber nonwoven material or yarn bonded material.

12. An absorbent article for personal care as claimed in clause 1 characterized 20 because said hollow polymer fiber nonwoven material is a side-to-body liner.

13. An absorbent article for personal care as claimed in clause 1 characterized 25 because said hollow polymer fiber nonwoven material is an emerging material. cf 43

14. An absorbent article for personal care as claimed in clause 1 characterized in that a lumen of said hollow metallocene polymer fiber is in a range of about 30 percent to about 6 percent by volume of said hollow metallocen polymer fiber.

15. An absorbent article for personal care comprising: a lower sheet impervious to liquid; a side-to-body liner comprising non-woven hollow polymer fiber material comprising a In the plurality of hollow polymer fibers and having a weight in a range of about 8 grams per square meter to about 200 grams per square meter, said hollow polymer fibers have an outer diameter in a range of about 7 microns. around 50 microns; and an absorbent core positioned between said lower leaf impermeable to the liquid and said liner side to body.

16. An absorbent article for the city 25, as claimed in clause 15, characterized in that said hollow polymer fibers are one-component, bicomponent fibers that have at least the segments.

17. An absorbent article for the city 5 personal as claimed in clause 15 characterized in that said basis weight of the hollow polymer fiber nonwoven material is in a range of about 10 grams per square meter to about 30 grams per square meter.

18. An absorbent article for personal care as claimed in clause 15 characterized in that said non-woven material is a yarn bonded material.

19. An absorbent article for the city 15 as claimed in clause 15 characterized in that said hollow polymer fibers comprise at least one polymer having a molecular weight distribution of less than about 3.5.

20. An absorbent article for personal care as claimed in clause 15 characterized in that said hollow polymer fibers comprise at least one polymer selected from the group consisting of metallocene, polypropylene, polyethylene, nylon, polyester polymers. combinations thereof.

21. An absorbent article for personal care as claimed in clause 15 characterized in that said hollow polymer fibers are bicomponent propylene-ethylene / polypropylene copolymer fibers.

22. An absorbent article for personal care as claimed in clause 15 characterized in that said hollow polymer fibers are copolymer fibers of polypropylene plus propylene butylene / polypropylene d bicomponent.

23. A nonwoven material comprising: a plurality of yarn-bonded hollow polymer fibers comprising at least one polymer having a polydispersity of less than about 3.5 and having a basis weight in the range of about 8 grams per square meter about 200 grams per meter square, said hollow polymer fibers have an outside diameter in a range of about 7 microns to about 50 microns.

24. A non-woven material as claimed in clause 23 characterized in that said hollow polymer fibers are one-component and two-component fibers and have at least two segments. ; < ~ >

25. A nonwoven material as claimed in clause 23 characterized in that said hollow polymer fibers comprise at least one polymer having a molecular weight distribution of less than about 3.5

26. A nonwoven material as claimed in clause 23 characterized in that said polymer is metallocene polypropylene.

27. A non-woven material as claimed in clause 23, characterized in that said hollow polymer fibers comprise at least one polymer having a polydispersity of less than about 3.

28. A nonwoven material as claimed in clause 23 characterized in that said hollow polymer fibers comprise at least one polymer having a polydispersity of less than about 2.5.

29. A nonwoven material as claimed in clause 23 characterized in that a lumen of said hollow metallocene polymer fiber is in a range of 10 percent to about 60 percent by volume of dich hollow metallocene polymer fiber. . 25 f.

30. A nonwoven material as claimed in clause 23 characterized in that a lumen of said hollow metallocene polymer fiber is in a range of about 30 percent to about 60 percent by volume 5 of said hollow metallocene polymer fiber.

31. An absorbing article for personal care that includes: 10 a hollow polymer fiber nonwoven material comprising a plurality of hollow polymer fibers comprising metallocene polymer.

32. An absorbent article for personal care as claimed in clause 31 characterized in that said metallocene polymer is a metallocene polypropylene.

33. An absorbent article for personal care as claimed in clause 31 characterized in that said hollow polymer fiber nonwoven material has a basis weight in a range of about 8 grams per square meter to about 200 grams per meter square.

34. An absorbent article for personal care as claimed in clause 31 characterized -AT 48 because said hollow polymer fibers have an outer diameter in a range of about 7 microns to about 5 microns.

35. An absorbent article for personal care as claimed in clause 31 characterized in that said hollow polymer fibers are one-component, bicomponent fibers comprising at least two segments. 10

36. An absorbent article for personal care as claimed in clause 31 characterized in that the hollow polymer fiber non-woven material is a yarn bonded material. 15

37. An absorbent article for personal care as claimed in clause 31 characterized in that a lumen of said hollow metallocene polymer fiber is in the range of 30 percent to about 60 percent po 20 volume of said hollow metallocene polymer fiber. SUMMARY An absorbent personal care article constructed of a hollow polymer fiber nonwoven material produced from a plurality of hollow polymer fibers and having a basis weight in the range of from about 8 grams per square meter to about 200 grams per square meter. The hollow polymer fibers of this non-woven fabric material have an outside diameter in the range of about 7 miera to about 50 microns. The hollow polymer fibers of this invention according to the embodiment are made of a metallocene polypropylene resin.