ZA200200663B

ZA200200663B - Biodisintegratable nonwovens with fluid management properties and disposable absorbent products containing same.

Info

Publication number: ZA200200663B
Application number: ZA200200663A
Authority: ZA
Inventors: Fu-Jya Tsai; Brigette C Wertheim
Original assignee: Kimberly Clark Co
Priority date: 1999-08-25
Filing date: 2002-01-24
Publication date: 2003-03-26

Description

BIODISINTEGRATABLE NONWOVENS WITH FLUID MANAGEMENT PROPERTIES AND DISPOSABLE

ABSORBENT PRODUCTS CONTAINING SAME

FIELD OF THE INVENTION

The present invention relates to a disposable absorbent product having a biodisintegratable nonwoven material having improved fluid management properties. The nonwoven material may be produced from polymer blends. These blends may include multicomponent fibers. These multicomponent fibers comprise an unreacted mixture of an aliphatic polyester polymer as a continuous phase, polyolefin microfibers as a discontinuous phase encased within the aliphatic polyester polymer continuous phase, and a compatibilizer for the aliphatic polyester polymer and the polyolefin microfibers. The multicomponent fiber exhibits substantial biodisintegratable properties yet is easily processed.

The biodisintegratable nonwoven materials may be used in a disposable absorbent product intended for the absorption of fluids such as body fluids.

BACKGROUND OF THE INVENTION

Disposable absorbent products currently find widespread use in many applications. For example, in the infant °° and child care areas, diapers and training pants have generally replaced reusable cloth absorbent articles. Other typical disposable absorbent products include feminine care products such as sanitary napkins or tampons, adult incontinence products, and health care — products such as surgical drapes or wound dressings. A typical disposable absorbent product generally comprises a composite structure including a liquid-permeable topsheet, a fluid acquisition layer, an absorbent structure, and a liquid-impermeable backsheet.

These products usually include some type of fastening system for fitting the product onto the wearer.

Disposable absorbent products are typically subjected to one or more liquid insults, such as of water, urine, menses, or blood, during use. As such, the outer cover materials of the disposable absorbent products are typically made of liquid- insoluble and liquid impermeable materials, such as polypropylene films, that exhibit a sufficient strength and handling capability so that the disposable absorbent product retains its integrity during use by a wearer and does not allow leakage of the liquid insulting the product.

Although current disposable baby diapers and other disposable absorbent products have been generally accepted by the public, these products still have need of improvement in specific areas. For example, many disposable absorbent products can be : difficult to dispose of. For example, attempts to flush many disposable absorbent products down a toilet into a sewage system typically lead to blockage of the toilet or pipes connecting the toilet to the sewage system. In particular, the outer cover materials typically used in the disposable absorbent products generally do not disintegrate or disperse when flushed down a toilet so that the disposable absorbent product cannot be disposed of in this way. If the outer cover materials are made very thin in order to reduce the overall bulk of the disposable absorbent product so as to reduce the likelihood of blockage of a toilet or a sewage pipe, then the outer cover material typically will not exhibit sufficient strength to prevent tearing or ripping as the outer cover material is subjected to the stresses of normal use by a wearer.

Furthermore, solid waste disposal is becoming an ever increasing concern throughout the world. As landfills continue to fill up, there has been an increased demand for material source — reduction in disposable products, the incorporation of more recyclable and/or degradable components in disposable products,

and the design of products that can be disposed of by means other than by incorporation into solid waste disposal facilities such as landfills.

As such, there is a need for new materials that may be used in disposable absorbent products that generally retain their integrity and strength during use, but after such use, the materials may be more efficiently disposed of. For example, the disposable absorbent product may be easily and efficiently disposed of by composting. Alternatively, the disposable absorbent product may be easily and efficiently disposed of to a liquid sewage system wherein the disposable absorbent product is capable of being degraded.

Although degradable monocomponent fibers are known, problems have been encountered with their use. In particular, known degradable fibers typically do not have good thermal dimensional stability such that the fibers usually undergo severe heat-shrinkage due to the polymer chain relaxation during downstream heat treatment processes such as thermal bonding or : lamination.

In contrast, polyolefin materials, such as polypropylene, typically exhibit good thermal dimensional stability but also have problems associated with their use. In particular, polyolefin fibers typically are hydrophobic and, and such, exhibit poor wettability, thus limiting their use in disposable absorbent products intended for the absorption of fluids such as body fluids.

Although surfactants can be used to improve the wettability of polyolefin fibers, the use of such surfactants introduces additional problems such as added cost, fugitivity or permanence, and toxicity. Furthermore, polyolefin fibers are generally not biodisintegratable or compostable.

It would therefore be desirable to prepare a biodisintegratable nonwoven material which includes fibers that exhibit the thermal dimensional stability of polyolefin materials yet are substantially biodisintegratable and are also wettable without the use of surfactants. A simple solution to this desire would be to simply mix a polyolefin material with a degradable material so as to gain the benefits of using both materials. However, the components of a multicomponent fiber generally need to be chemically compatible, so that the components effectively adhere to each other, and have similar rheological characteristics, so that the multicomponent fiber exhibits minimum strength and other mechanical and processing properties. It has therefore proven to be a challenge to those skilled in the art to combine components that meet these basic processing needs as well as meeting the desire that the entire multicomponent fiber be effectively substantially degradable and hydrophilic.

It is therefore desirable to provide a biodisintegratable nonwoven material which includes multicomponent fibers which are substantially degradable in the environment. It is also desirable to provide a substantially degradable multicomponent fiber which has good thermal dimensional stability and 1s hydrophilic without the substantial use of surfactants. Finally, it is also desirable to : provide a biodisintegratable nonwoven material having a substantially degradable multicomponent fiber which is easily and efficiently prepared and which is suitable for use in preparing these biodisintegratable nonwoven materials. " SUMMARY OF THE INVENTION

The present invention concerns a biodisintegratable nonwoven material that is substantially biodisintegratable and yet which is easily prepared and readily processable into desired final structures.

One aspect of the present invention concerns a biodisintegratable nonwoven material which includes a thermoplastic composition that comprises a mixture of a first component, a second component, and a third component.

One embodiment of such a thermoplastic composition comprises an unreacted mixture of an aliphatic polyester polymer — as a substantially continuous phase, polyolefin microfibers as a substantially discontinuous phase encased within the aliphatic polyester polymer substantially continuous phase, and a compatibilizer for the aliphatic polyester polymer and the polyolefin microfibers.

In another aspect, the present invention concerns a biodisintegratable nonwoven material which includes a multicomponent fiber that is substantially degradable and yet which is easily prepared and readily processable into desired final structures.

One aspect of the present invention concerns a biodisintegratable nonwoven material which includes a multicomponent fiber that comprises an unreacted mixture of an aliphatic polyester polymer as a substantially continuous phase, polyolefin microfibers as a substantially discontinuous phase encased within the aliphatic polyester polymer substantially continuous phase, and a compatibilizer for the aliphatic polyester polymer and the polyolefin microfibers. :

One embodiment of such a nonwoven structure is a fluid acquisition layer useful in a disposable absorbent product. X

One aspect of the present invention concerns a multicomponent fiber that includes an unreacted thermoplastic mixture of an aliphatic polyester polymer as a substantially continuous phase, polyolefin microfibers as a substantially discontinuous phase encased within the aliphatic polyester polymer substantially continuous phase, and a compatibilizer for the aliphatic polyester polymer and the polyolefin microfibers as one component of the multicomponent fiber. The fiber may be in any configuration such that the thermoplastic mixture is exposed to the fiber surface as in sheath-core, eccentric sheath-core, side-by-side, or any other configuration. Such fibers could be made in to any type of nonwoven material.

In another aspect, the present invention concerns a disposable absorbent product comprising the biodisintegratable nonwoven material disclosed herein.

In another aspect, the present invention concerns a process for preparing the biodisintegratable nonwoven material disclosed herein.

DETAILED DESCRIPTION OF THE INVENTION

The present invention is directed to a disposable absorbent product having a biodisintegratable nonwoven material which demonstrates higher contact angle hysteresis, quicker intake times, and improved skin dryness as compared to prior art nonwoven materials. In addition, these biodisintegratable nonwoven materials also exhibit high wetting rates, which is unexpected based upon the higher hysteresis values.

These biodisintegratable nonwoven materials preferably include a thermoplastic composition which includes a first component, a second component, and a third component. As used herein, the term “thermoplastic” is meant to refer to a material that softens when exposed to heat and substantially returns to its . original condition when cooled to room temperature.

It has been discovered that, by using an unreacted mixture of an aliphatic polyester polymer as a substantially continuous phase, polyolefin microfibers as a substantially discontinuous phase encased within the aliphatic polyester polymer substantially continuous phase, and a compatibilizer for the aliphatic polyester polymer and the polyolefin microfibers, a thermoplastic composition may be prepared wherein such thermoplastic composition is substantially degradable yet which thermoplastic composition is easily processable into nonwoven structures that exhibit effective fibrous mechanical properties and liquid handling properties.

The first component in the thermoplastic composition is an aliphatic polyester polymer. Suitable aliphatic polyester polymers include, but are not limited to, poly(lactic acid), polybutylene succinate, polybutylene succinate-co-adipate, — polyhydroxybutyrate-co-valerate, polycaprolactone, sulfonated polyethylene terephthalate, mixtures of such polymers, or copolymers of such polymers.

In one embodiment of the present invention, it is desired that the aliphatic polyester polymer used is poly(lactic acid). Poly(lactic acid) polymer is generally prepared by the polymerization of lactic acid. However, it will be recognized by one skilled in the art that a chemically equivalent material may also be prepared by the polymerization of lactide. As such, as used herein, the term “poly(lactic acid) polymer” is intended to represent the polymer that is prepared by either the polymerization of lactic acid or lactide.

Lactic acid and lactide are known to be asymmetrical molecules, having two optical isomers referred to, respectively, as the levorotatory (hereinafter referred to as “L”) enantiomer and the dextrorotatory (hereinafter referred to as “D”) enantiomer. As a result, by polymerizing a particular enantiomer or by using a : mixture of the two enantiomers, it is possible to prepare different polymers that are chemically similar yet which have different X properties. In particular, it has been found that by modifying the stereochemistry of a poly(lactic acid) polymer. it is possible to control, for example, the melting temperature, melt rheology, and crystallinity of the polymer. By being able to control such properties, it is possible to prepare a multicomponent fiber exhibiting desired melt strength, mechanical properties, softness, and processability properties so as to be able to make attenuated, heat set, and crimped fibers.

It is generally desired that the aliphatic polyester polymer be present in the thermoplastic composition in an amount effective to result in the thermoplastic composition exhibiting desired properties. The aliphatic polyester polymer will be present in the thermoplastic composition in a weight amount that is less than 100 weight percent, beneficially between about 45 weight percent to about 90 weight percent, suitably between about 50 weight percent to about 88 weight percent, and more suitably between about 55 weight percent to about 70 weight percent,

wherein all weight percents are based on the total weight amount of the aliphatic polyester polymer, the polyolefin microfiber, and the compatibilizer present in the thermoplastic composition. The compositional ratio of the three components in the thermoplastic composition is generally important to maintaining the substantial biodegradability of the thermoplastic composition because the aliphatic polyester polymer generally needs to be in a substantially continuous phase in order to maintain access to the biodisintegratable portion of the thermoplastic composition. An approximation of the limits of component ratios can be determined based on the densities of the components. The density of a component is converted to a volume (assume 100g of each component), the volumes of the components are added together for a total thermoplastic composition volume and the components’ weight averages calculated to establish the approximate minimum ratio of each component needed to produce a thermoplastic composition with a volumetric majority of the aliphatic polyester : polymer in the blend.

It is generally desired that the aliphatic polyester polymer exhibit a weight average molecular weight that is effective for the thermoplastic composition to exhibit desirable melt strength, fiber mechanical strength, and fiber spinning properties.

In general, if the weight average molecular weight of an aliphatic polyester polymer is too high, this represents that the polymer chains are heavily entangled which may result in a thermoplastic composition comprising that aliphatic polyester polymer being difficult to process. Conversely, if the weight average molecular weight of an aliphatic polyester polymer is too low, this represents that the polymer chains are not entangled enough which may result in a thermoplastic composition comprising that aliphatic polyester polymer exhibiting a relatively weak melt strength, making high speed processing very difficult. Thus, aliphatic polyester polymers suitable for use in the present invention exhibit weight average — molecular weights that are beneficially between about 10,000 to about 2.000,000, more beneficially between about 50,000 to about

400,000, and suitably between about 100,000 to about 300,000.

The weight average molecular weight for polymers or polymer blends can be determined using a method as described in the Test

Methods section herein.

It is also desired that the aliphatic polyester polymer exhibit a polydispersity index value that is effective for the thermoplastic composition to exhibit desirable melt strength, fiber mechanical strength, and fiber spinning properties. As used herein, “polydispersity index” is meant to represent the value obtained by dividing the weight average molecular weight of a polymer by the number average molecular weight of the polymer. In general, if the polydispersity index value of an aliphatic polyester polymer is too high, a thermoplastic composition comprising that aliphatic polyester polymer may be difficult to process due to inconsistent processing properties caused by polymer segments comprising low molecular weight polymers that have lower melt strength properties during spinning. Thus, it is desired that the aliphatic polyester polymer exhibits a polydispersity index value that is beneficially between about 1 to about 15, more beneficially between about 1 to about 4, and suitably between about 1 to about 3. The number average molecular weight for polymers or polymer blends can be determined using a method as described in the Test

Methods section herein.

In the present invention, it is desired that the aliphatic polyester polymer be biodegradable. As a result, the nonwoven material including the aliphatic polyester polymer will be substantially degradable when disposed of to the environment and exposed to air and/or water. As used herein, “biodegradable” is meant to represent that a material degrades from the action of naturally occurring microorganisms such as bacteria, fungi, and algae. Using biodegradable materials permits the formation of biodisintegratable materials. As used herein, “biodisintegratable” 1s meant to represent that a portion of the nonwoven material biodegrades, leaving an amount of material that is not able to be seen by the unaided eye.

In the present invention, it is also desired that the aliphatic polyester polymer be compostable. As a result, nonwoven material including the aliphatic polyester polymer will be substantially compostable when disposed of to the environment and exposed to air and/or water. As used herein, “compostable” is meant to represent that a material is capable of undergoing biological decomposition in a compost site such that the material is not visually distinguishable and breaks down into carbon dioxide, water, inorganic compounds, and biomass, at a rate consistent with known compostable materials.

The second component of the thermoplastic composition is polyolefin microfibers. Polyolefins are known to those skilled in the art. Any polyolefin capable of being fabricated into an article, such as a microfiber, is believed suitable for use in the present invention. Exemplary of polyolefins suitable for use in the present invention are the homopolymers and copolymers comprising repeating units formed from one or more aliphatic : hydrocarbons, including ethylene, propylene, butene, pentene, hexene, heptene, octene, 1,3 -butadiene, and 2-methyl-1,3 - butadiene. The polyolefins may be high or low density and may be generally linear or branched chain polymers. Methods of forming polyolefins are known to those skilled in the art.

Polyolefins, such as those described above, are generally hydrophobic in nature. As used herein, the term “hydrophobic” refers to a material having a contact angle of water in air of at least 90 degrees. In contrast, as used herein, the term “hydrophilic” refers to a material having a contact angle of water in air of less than 90 degrees. For the purposes of this application, contact angle measurements may be determined as set forth in

Robert J. Good and Robert J. Stromberg, Ed., in “Surface and

Colloid Science - Experimental Methods”, Vol. II, (Plenum Press, 1979), pages 63-70.

It is generally desired that both the aliphatic polyester — polymer and the polyolefin be melt processable. It is therefore desired that the aliphatic polyester polymer and the polyolefin exhibit a melt flow rate that is beneficially between about 1 gram per 10 minutes to about 200 grams per 10 minutes, suitably between about 10 grams per 10 minutes to about 100 grams per 10 minutes, and more suitably between about 20 grams per 10 minutes to about 40 grams per 10 minutes. The melt flow rate of a material may be determined according to ASTM Test Method D1238-E incorporated in its entirety herein by reference.

In the present invention, the polyolefin is used in the form of a microfiber. As used herein, the term "microfiber" is meant to refer to a fibrous material having a diameter that is less than about 50 micrometers, beneficially less than about 25 micrometers more beneficially less than about 10 micrometers, suitably less than about 5 micrometers, and most suitably less than about 1 micrometer.

In one embodiment of the present invention, the polyolefin microfiber comprises a percentage of the cross sectional area of a multicomponent fiber prepared from the thermoplastic composition of the present invention that is effective for the : multicomponent fiber to exhibit desirable melt strength, fiber mechanical strength, and fiber spinning properties In general if the polyolefin microfiber comprises a percentage of the cross sectional area of a multicomponent fiber that is too high, this generally results in a nonwoven material that will not be substantially biodisintegratable or that will be difficult to produce.

Conversely, if the polyolefin microfiber comprises a percentage of the cross sectional area of a multicomponent fiber that is too low, this generally results in a nonwoven material that will not exhibit effective structural properties or that may be difficult to process.

Thus, the polyolefin microfiber desirably comprises a percentage of the cross sectional area of a multicomponent fiber that is beneficially less than about 20 percent of the cross sectional area of the multicomponent fiber, more beneficially less than about 15 percent of the cross sectional area of the multicomponent fiber, and suitably less than about 10 percent of the cross sectional area of the multicomponent fiber.

As used herein, the term "fiber" or "fibrous" is meant to refer to a material wherein the length to diameter ratio of such material 1s greater than about 10. Conversely, a "nonfiber" or "nonfibrous" material is meant to refer to a material wherein the length to diameter ratio of such material is about 10 or less.

The polyolefin is generally desired to be in the form of a microfiber so as to allow the polyolefin to effectively function as a structural support within the thermoplastic composition so as to prevent a substantial thermal dimensional-shrinkage of the thermoplastic composition during processing while generally maintaining a desired degree of substantial biodegradability of the thermoplastic composition.

It is generally desired that the polyolefin microfibers be present in the thermoplastic composition in an amount effective to result in the thermoplastic composition exhibiting desired properties. The polyolefin microfibers will be present in the thermoplastic composition in a weight amount that is beneficially : between greater than 0 weight percent to about 45 weight percent, suitably between about 5 weight percent to about 40 weight percent, and more suitably between about 10 weight percent to about 30 weight percent, wherein all weight percents are based on the total weight amount of the aliphatic polyester polymer, the polyoletin microfiber, and the compatibilizer present in the thermoplastic composition. It is generally important for the polyolefin to be a substantially discontinuous phase of the thermoplastic composition so that the polyolefin microfibers can provide structural support to the thermoplastic composition or materials formed from the thermoplastic composition, such as fibers or nonwovens, without negatively affecting the biodegradability of the aliphatic polyester or of the substantial biodegradability of the thermoplastic composition or materials formed from the thermoplastic composition.

Either separately or when mixed together, the aliphatic ” polyester polymer and the polyolefin microfiber are generally hydrophobic. However, it is generally desired that the thermoplastic composition used in the present invention, and nonwoven materials prepared from the thermoplastic composition, generally be hydrophilic so that such materials are useful in disposable absorbent products which are insulted with aqueous liquids such as water, urine, menses, or blood. Thus, it has been found desirable to use another component as a surfactant in the thermoplastic composition of the present invention in order to achieve the desired hydrophilic properties.

Furthermore, it has been found desirable to improve the processability of the aliphatic polyester polymer and the polyolefin microfibers, since such polymers are not chemically identical and are, therefore, somewhat incompatible with each other which tends to negatively affect the processing of a mixture of such polymers. For example, the aliphatic polyester polymer and the polyolefin microfibers are sometimes difficult to effectively mix and prepare as an essentially homogeneous mixture : on their own. Generally, then, it has been found desirable to use a compatibilizer to aid in the effective preparation and processing of the aliphatic polyester polymer and the polyolefin microfibers into a single thermoplastic composition.

Therefore, the third component in the thermoplastic composition is a compatibilizer for the aliphatic polyester polymer and the polyolefin microfibers. Compatibilizers suitable for use in the present invention will generally comprise a hydrophilic section which will generally be compatible to the aliphatic polyester polymer and a hydrophobic section which will generally be compatible to the polyolefin microfibers. These hydrophilic and hydrophobic sections will generally exist in separate blocks so that the overall compatibilizer structure may be di-block or random block. It is generally desired that the compatibilizer initially functions as a plasticizer in order to improve the preparation and processing of the thermoplastic composition. It is then generally desired that the compatibilizer serves as a surfactant in a material processed from the thermoplastic composition, the nonwoven material of the present invention, by modifying the contact angle of water in air of the processed material. The hydrophobic portion of the compatibilizer may be, but is not limited to, a polyolefin such as polyethylene or polypropylene. The hydrophilic portion of the compatibilizer may contain ethylene oxide, ethoxylates, glycols, alcohols or any combinations thereof. Examples of suitable compatibilizers include UNITHOX®480 and UNITHOX®750 ethoxylated alcohols, or UNICID® Acid Amide Ethoxylates, all available from Petrolite Corporation of Tulsa, Oklahoma.

It is generally desired that the compatibilizer exhibit a weight average molecular weight that is effective for the thermoplastic composition to exhibit desirable melt strength, fiber mechanical strength, and fiber spinning properties. In general, if the weight average molecular weight of a compatibilizer is too high, the compatibilizer will not blend well with the other components in the thermoplastic composition because the compatibilizer’s viscosity will be so high that it lacks the mobility needed to blend. Conversely, if the weight average molecular : weight of the compatibilizer is too low, this represents that the compatibilizer will generally not blend well with the other components and have such a low viscosity that it causes processing problems. Thus, compatibilizers suitable for use in the present invention exhibit weight average molecular weights that are beneficially between about 1,000 to about 100,000, suitably between about 1,000 to about 50,000, and more suitably between about 1,000 to about 10,000. The weight average molecular weight for a compatibilizer material can be determined using methods known to those skilled in the art.

It 1s generally desired that the compatibilizer exhibit an effective hydrophilic-lipophilic balance ratio (HLB ratio). The

HLB ratio of a material describes the relative ratio of the hydrophilicity of the material. The HLB ratio is calculated as the weight average molecular weight of the hydrophilic portion divided by the total weight average molecular weight of the - material, which value is then multiplied by 20. If the HLB ratio value is too low, the material will generally not provide the desired improvement in hydrophilicity. Conversely, if the HLB ratio value is too high, the material will generally not blend into the thermoplastic composition because of chemical incompatibility and differences in viscosities with the other components. Thus, compatibilizers useful in the present invention exhibit HLB ratio values that are beneficially between about 10 to about 40, suitably between about 10 to about 20, and more suitably between about 12 to about 18.

It is generally desired that the compatibilizer be present in the thermoplastic composition in an amount effective to result in the thermoplastic composition exhibiting desired properties. In general, a minimal amount of the compatibilizer will be needed to achieve an effective blending and processing with the other components in the thermoplastic composition. In general, too much of the compatibilizer will lead to processing problems of the thermoplastic composition. The compatibilizer will be present in the thermoplastic composition in a weight amount that is beneficially between about 3 weight percent to about 25 weight percent, more beneficially between about 10 weight percent to about 25 weight percent, suitably between about 12 weight percent to about 20 weight percent, and more suitably between about 13 weight percent to about 18 weight percent, wherein all weight percents are based on the total weight amount of the aliphatic polyester polymer, the polyolefin microfiber, and the compatibilizer present in the thermoplastic composition.

While the principal components of the thermoplastic composition have been described in the foregoing, such thermoplastic composition is not limited thereto and can include other components not adversely effecting the desired properties of the resulting biodisintegratable nonwoven materials. Exemplary materials which could be used as additional components would include, without limitation, pigments, antioxidants, stabilizers, surfactants, waxes, flow promoters, solid solvents, plasticizers, nucleating agents, particulates, and materials added to enhance processability of the thermoplastic composition. If such additional components are included in a thermoplastic composition, it is generally desired that such additional components be used in an amount that is beneficially less than about 5 weight percent, more beneficially less than about 3 weight percent, and suitably less than about 1 weight percent, wherein all weight percents are based on the total weight amount of the aliphatic polyester polymer, the polyolefin microfiber, and the compatibilizer present in the thermoplastic composition.

The thermoplastic composition used in the present invention 1s generally the resulting morphology of a mixture of the aliphatic polyester polymer, the polyolefin polymer, the compatibilizer, and, optionally, any additional components. The polyolefin polymer forms a substantially discontinuous phase encased within the aliphatic polyester polymer substantially continuous phase. In order to achieve the desired properties for the thermoplastic composition, it is desirable that the aliphatic polyester polymer, the polyolefin microfibers, and the : compatibilizer remain substantially unreacted with each other. As such, each of the aliphatic polyester polymer, the polyolefin microfibers, and the compatibilizer remain distinct components of the thermoplastic composition. Furthermore, it is desired that the aliphatic polyester polymer forms a substantially continuous phase and that the polyolefin microfibers form a substantially discontinuous phase, wherein the aliphatic polyester polymer continuous phase substantially encases the polyolefin microfibers within its structure. As used herein, the term “encase”, and related terms, are intended to mean that the aliphatic polyester polymer continuous phase substantially encloses or surrounds the polyolefin microfibers.

In one embodiment of the present invention, after dry mixing together the aliphatic polyester polymer, the polyolefin polymer, and the compatibilizer to form a thermoplastic composition dry mixture, such thermoplastic composition dry — mixture is beneficially agitated, stirred, or otherwise blended to effectively uniformly mix the aliphatic polyester polymer, the polyolefin polymer, and the compatibilizer such that an essentially homogeneous dry mixture is formed. The dry mixture may then be melt blended in, for example, an extruder, to effectively uniformly mix the aliphatic polyester polymer, the polyolefin polymer, and the compatibilizer such that an essentially homogeneous melted mixture is formed. The essentially homogeneous melted mixture may then be cooled and pelletized. Alternatively, the essentially homogeneous melted mixture may be sent directly to a spin pack or other equipment for forming fibers or a nonwoven structure.

Alternative methods of mixing together the components include first mixing together the aliphatic polyester polymer and the polyolefin polymer and then adding the compatibilizer to such a mixture in, for example, an extruder being used to mix the components together. In addition, it is also possible to initially melt mix all of the components together at the same time. Other methods of mixing together the components of the present invention are also possible and will be easily recognized by one skilled in the art.

The present invention also utilizes a multicomponent fiber which is prepared from the thermoplastic composition previously described. For purposes of illustration only, the present description will generally be in terms of a multicomponent fiber comprising only three components. However, it should be understood that the biodisintegratable nonwoven materials of the present invention may include fibers with three or more components. In one embodiment, the thermoplastic composition may be used to form the sheath of a multicomponent fiber while a polyolefin, such as polypropylene or polyethylene, is used to form the core. Suitable structural geometries for multicomponent fibers include pie shape or side by side configurations.

With the aliphatic polyester polymer forming a substantially continuous phase, the aliphatic polyester polymer will generally provide an exposed surface on at least a portion of the multicomponent fiber which will generally permit thermal bonding of the multicomponent fiber to other fibers which may be the same or different from the multicomponent fiber. As a result, the multicomponent fiber can then be used to form thermally bonded fibrous nonwoven structures such as a nonwoven web. The polyolefin microfibers in the multicomponent fiber generally provide strength or rigidity to the multicomponent fiber and, thus, to any nonwoven structure comprising the multicomponent fiber.

In order to provide such strength or rigidity to the multicomponent fiber, it is generally desired that the polyolefin microfibers be substantially continuous along the length of the multicomponent fiber.

Typical conditions for thermally processing the various components include using a shear rate that is beneficially between about 100 seconds” to about 10000 seconds’, more beneficially between about 500 seconds™ to about 5000 seconds, suitably between about 1000 seconds’ to about 2000 seconds, and most suitably at about 1000 seconds”. Typical conditions for thermally processing the components also include using a temperature that is beneficially between about 100°C to about 500°C, more beneficially between about 150°C to about 300°C, and suitably between about 175°C to about 250°C.

Methods for making multicomponent fibers are well known and need not be described here in detail. The melt spinning of polymers includes the production of continuous filament, such as spunbond or meltblown, and non-continuous filament, such as staple and short-cut fibers, structures. To form a spunbond or meltblown fiber, generally, a thermoplastic composition is extruded and fed to a distribution system where the thermoplastic composition is introduced into a spinneret plate. The spun fiber is then cooled, solidified, and drawn by an aerodynamic system, to be formed into a conventional nonwoven. Meanwhile, to produce short-cut or staple fiber, rather than being directly formed into a nonwoven structure, the spun fiber is cooled, solidified, and drawn, generally by a mechanical rolls system, to an intermediate filament : diameter and collected. Subsequently, the fiber may be “cold drawn” at a temperature below its softening temperature, to the desired finished fiber diameter and crimped or texturized and cut into a desirable fiber length.

The process of cooling an extruded thermoplastic composition to ambient temperature is usually achieved by blowing ambient or sub-ambient temperature air over the extruded thermoplastic composition. It can be referred to as quenching or super-cooling because the change in temperature is usually greater than 100°C and most often greater than 150°C over a relatively short time frame, such as in seconds.

Multicomponent fibers can be cut into relatively short lengths, such as staple fibers which generally have lengths in the range of about 25 to about 50 millimeters and short-cut fibers which are even shorter and generally have lengths less than about 18 millimeters. See, for example, US Patent 4,789,592 to

Taniguchi et al, and US Patent 5,336,552 to Strack et al., both of which are incorporated herein by reference in their entirety.

The resultant multicomponent fibers are desired to exhibit an improvement in hydrophilicity, evidenced by a decrease in the contact angle of water in air. The contact angle of water in air of a fiber sample can be measured as either an advancing or a receding contact angle value because of the nature of the testing procedure. The advancing contact angle generally measures a material’s initial response to a liquid, such as water. The receding contact angle generally gives a measure of how a material will perform over the duration of a first insult, or exposure to liquid, as well as over following insults. A lower receding contact angle means that the material is becoming more hydrophilic during the liquid exposure and will generally then be able to transport liquids more consistently. The receding contact angle data is used to establish the highly hydrophilic nature of a multicomponent fiber of the present invention although it is preferable that a decrease in the advancing contact angle of the multicomponent fiber also takes place.

Thus, in one embodiment, it is desired that the thermoplastic composition or a multicomponent fiber exhibit a

Receding Contact Angle value that is beneficially less than about 55 degrees, more beneficially less than about 40 degrees, suitably less than about 25 degrees, more suitably less than about 20 degrees, and most suitably less than about 10 degrees, wherein the receding contact angle is determined by the method that is described in the Test Methods section herein.

Typical aliphatic polyester-based materials often undergo heat shrinkage during downstream thermal processing.

The heat-shrinkage mainly occurs due to the thermally-induced chain relaxation of the polymer segments in the amorphous phase and incomplete crystalline phase. To overcome this problem, it is generally desirable to maximize the crystallization of the material before the bonding stage so that the thermal energy goes directly to melting rather than to allow for chain relaxation and reordering of the incomplete crystalline structure. The typical solution to this problem is to subject the material to a heat-setting treatment. As such, when prepared materials, such as fibers, are subjected to heat-setting upon reaching a bonding roll, the fibers won't substantially shrink because such fibers are already fully or highly oriented. The present invention alleviates the need for this additional processing step because of the morphology of the multicomponent fiber. As discussed earlier, the polyolefin microfibers generally provide a reinforcing structure which minimizes the expected heat shrinkage of the aliphatic polyester.

In one embodiment, it is desired that the nonwoven material utilize a thermoplastic composition or a multicomponent fiber which exhibits an amount of shrinking, as quantified by a

Heat Shrinkage value, at a temperature of about 100°C, that is beneficially less than about 10 percent, more beneficially less than about 5 percent, suitably less than about 2 percent, and more suitably less than about 1 percent, wherein the amount of shrinking is based upon the difference between the initial and final lengths of a fiber divided by the initial length multiplied by 100. The method ~ by which the amount of shrinking that a fiber exhibits may be determined is included in the Test Methods section herein.

The resultant thermoplastic composition and multicomponent fibers are used to form biodisintegratable nonwoven materials which exhibit an increase in high contact angle hysteresis values, quicker intake times for insults, and improved skin dryness, while also keeping very high wetting rates

The biodisintegratable nonwoven materials of the present invention are suited for use in disposable products including disposable absorbent products such as diapers, adult incontinent products, and bed pads; in catamenial devices such as sanitary napkins, and tampons; and other absorbent products such as wipes, bibs, wound dressings, and surgical capes or drapes.

Accordingly, in another aspect, the present invention relates to a disposable absorbent product comprising the nonwoven material previously described.

In one embodiment of the present invention, the multicomponent fibers are formed into a fibrous matrix for incorporation into a disposable absorbent product. A fibrous matrix may take the form of, for example, a fibrous nonwoven web. Fibrous nonwoven webs may be made completely from the multicomponent fibers or they may be blended with other fibers.

The length of the fibers used may depend on the particular end use contemplated. Where the fibers are to be degraded in water as, for example, in a toilet, it is advantageous if the lengths are maintained at or below about 15 millimeters.

In one embodiment of the present invention, a disposable absorbent product is provided, which disposable absorbent product generally comprises a composite structure including a liquid-permeable topsheet, a fluid acquisition layer, an absorbent structure, and a liquid-impermeable backsheet, wherein at least one of the liquid-permeable topsheet, the fluid acquisition layer, or the liquid-impermeable backsheet comprises the nonwoven material of the present invention. In some instances, it may be beneficial for all three of the topsheet, the fluid acquisition layer, and the backsheet to comprise the nonwoven material of the present invention.

In another embodiment, the disposable absorbent product may comprise generally a composite structure including a liquid-permeable topsheet, an absorbent structure, and a liquid- impermeable backsheet, wherein at least one of the liquid- permeable topsheet or the liquid-impermeable backsheet comprises the nonwoven material of the present invention.

In another embodiment of the present invention, the nonwoven material may be prepared on a spunbond line. Resin pellets comprising the thermoplastic materials previously described are formed and predried. Then, they are fed to a single extruder.

The fibers may be drawn through a fiber draw unit (FDU) or air- drawing unit onto a forming wire and thermally bonded. However, other methods and preparation techniques may also be used.

Exemplary disposable absorbent products are generally described in US-A-4,710,187; US-A-4,762,521; US-A- 4,770,656; and US-A-4,798,603; which references are incorporated herein by reference.

Absorbent products and structures according to all aspects of the present invention are generally subjected, during use, to multiple insults of a body liquid. Accordingly, the absorbent products and structures are desirably capable of absorbing multiple insults of body liquids in quantities to which the absorbent ~ products and structures will be exposed during use. The insults are generally separated from one another by a period of time.

TEST METHODS

Melting Temperature

The melting temperature of a material was determined using differential scanning calorimetry. A differential scanning calorimeter, under the designation Thermal Analyst 2910

Differential Scanning Calorimeter, which was outfitted with a liquid nitrogen cooling accessory and used in combination with :

Thermal Analyst 2200 analysis software (version 8.10) program,

both available from T.A. Instruments Inc. of New Castle,

Delaware, was used for the determination of melting temperatures.

The material samples tested were either in the form of fibers or resin pellets. It was preferred to not handle the material samples directly, but rather to use tweezers and other tools, so as not to introduce anything that would produce erroneous results.

The material samples were cut, in the case of fibers, or placed, in the case of resin pellets, into an aluminum pan and weighed to an accuracy of 0.0lmg on an analytical balance. If needed, a lid was crimped over the material sample onto the pan.

The differential scanning calorimeter was calibrated using an indium metal standard and a baseline correction performed, as described in the manual for the differential scanning calorimeter. A material sample was placed into the test chamber of the differential scanning calorimeter for testing and an empty pan ts used as a reference. All testing was run with a 55 cubic centimeter/minute nitrogen (industrial grade) purge on the test chamber. The heating and cooling program was a 2 cycle test that begins with equilibration of the chamber to -75°C, followed by a heating cycle of 20°C/minute to 220°C, followed by a cooling cycle at 20°C/minuie io -75°C, and then another heating cycle of 20°C/minute to 220°C.

The results were evaluated using the analysis software program wherein the glass transition temperature (Tg) of inflection, endothermic and exothermic peaks were identified and quantified.

The glass transition temperature was identified as the area on the line where a distinct change in slope occurs and then the melting temperature is determined using an automatic inflection calculation.

Apparent Viscosity

A capillary rheometer, under the designation Gottfert

Rheograph 2003 capillary rheometer, which was used in combination with WinRHEO (version 2.31) analysis software, both available from Gottfert Company of Rock Hill, South Carolina,

was used to evaluate the apparent viscosity rheological properties of material samples. The capillary rheometer setup included a 2000 bar pressure transducer and a 30 mm length/30 mm active length/]1 mm diameter/0 mm height/180° run in angle, round hole capillary die.

If the material sample being tested demonstrated or was known to have water sensitivity, the material sample was dried in a vacuum oven above its glass transition temperature, i.e. above 55 or 60°C for poly(lactic acid) materials, under a vacuum of at least 15 inches of mercury with a nitrogen gas purge of at least 30 standard cubic feet per hour for at least 16 hours.

Once the instrument was warmed up and the pressure transducer was calibrated, the material sample was loaded incrementally into the column, packing resin into the column with a ramrod each time to ensure a consistent melt during testing.

After material sample loading, a 2 minute melt time preceded each test to allow the material sample to completely melt at the test “temperature. The capillary rheometer took data points automatically and determined the apparent viscosity (in

Pascal-second) at 7 apparent shear rates (in second): 50, 100, 200, 500, 1000, 2000, and 5000. When examining the resultant curve it was important that the curve be relatively smooth. If there - were significant deviations from a general curve from one point to another, possibly due to air in the column, the test run was repeated to confirm the results.

The resultant rheology curve of apparent shear rate versus apparent viscosity gives an indication of how the material sample will run at that temperature in an extrusion process. The apparent viscosity values at a shear rate of at least 1000 second’ are of specific interest because these are the typical conditions found in commercial fiber spinning extruders.

Molecular Weight _

A gas permeation chromatography (GPC) method was used to determine the molecular weight distribution of samples, such as of poly(lactic acid) whose weight average molecular weight (M,,) is between about 800 to about 400,000.

The GPC was set up with two PL gel Mixed K linear 5 micron, 7.5 x 300 millimeter analytical columns in series. The column and detector temperatures were 30°C. The mobile phase was high-performance liquid chromatography (HPLC) grade tetrahydrofuran (THF). The pump rate was 0.8 milliliter per minute with an injection volume of 25 microliters. Total run time was 30 minutes. It is important to note that new analytical columns must be installed about every 4 months, a new guard column about every month, and a new in-line filter about every month.

Standards of polystyrene polymers, obtained from Aldrich

Chemical Co., were mixed into a solvent of dichloromethane(DCM): THF (10:90), both HPLC grade, to obtain 1 mg/mL concentrations. Multiple polystyrene standards could be combined in one standard solution provided that their peaks do not overlap when chromatographed. A range of standards of about 687 to 400,000 molecular weight were prepared. Examples of standard mixtures with Aldrich polystyrenes of varying weight average molecular weights include: Standard 1 (401,340; 32,660; 2,727),

Standard 2 (45,730; 4,075), Standard 3 (95,800; 12,860) and

Standard 4 (184,200; 24,150; 687).

Next, the stock check standard was prepared. First, 10g of a 200,000 molecular weight poly(lactic acid) standard,

Catalog#19245 obtained from Polysciences Inc., was dissolved to 100ml of HPLC grade DCM in a glass jar with a lined lid using an orbital shaker (at least 30 minutes). Next. the mixture was poured out onto a clean, dry, glass plate and the solvent allowed to evaporate, then placed in a 35°C preheated vacuum oven and dried for about 14 hours under a vacuum of 25mm of mercury. Next, the poly(lactic acid) was removed from the oven and the film cut into small strips. Immediately, the samples were ground using a grinding mill (with a 10 mesh screen) taking care not to add too much sample and causing the grinder to freeze up. A few grams of the ground sample were stored in a dry glass jar in a dessicator,

Claims

CLAIMS What is claimed is:

l. A biodisintegratable nonwoven material comprising a plurality of fibers of a thermoplastic composition, wherein the thermoplastic composition comprises:

a. an aliphatic polyester polymer in a weight amount that is between about 45 to about 90 weight percent, wherein the aliphatic polyester polymer forms a substantially continuous phase;

b. polyolefin microfibers in a weight amount that 1s between greater than 0 to about 45 weight percent, wherein the polyolefin microfibers have a diameter that is less than about 50 micrometers and the polyolefin microfibers form a substantially discontinuous phase encased within the aliphatic polyester polymer substantially continuous phase; and c. a compatibilizer, which exhibits a hydrophilic- lipophilic balance ratio that is between about 10 to about 40, in a weight amount that is between about 7 to about 25 weight percent, wherein all weight percents are based on the total weight amount of the aliphatic polyester polymer; the polyolefin microfibers, and the compatibilizer present in the thermoplastic composition.
2. The biodisintegratable nonwoven material of Claim 1, wherein the aliphatic polyester polymer is selected from the group consisting of poly(lactic acid), polybutylene succinate, polybutylene succinate-co-adipate, polyhydroxybutyrate-co- valerate, polycaprolactone, sulfonated polyethylene terephthalate, mixtures of such polymers, and copolymers of such polymers.
3. The biodisintegratable nonwoven material of Claim 2, _ wherein the aliphatic polyester polymer is poly(lactic acid).
4. The biodisintegratable nonwoven material of Claim 1, wherein the polyolefin is selected from the group consisting of homopolymers and copolymers comprising repeating units selected from the group consisting of ethylene, propylene, butene, pentene, hexecne, heptene, octene, 1,3 -butadiene, and 2-methyl-1,3 - butadiene.
5. The biodisintegratable nonwoven material of Claim 4, wherein the polyolefin is selected from the group consisting of polyethylene and polypropylene.
6. The biodisintegratable nonwoven material of Claim 1, wherein the polyolefin microfibers have a diameter that is less than about 25 micrometers.
7. The biodisintegratable nonwoven material of Claim 1, wherein the polyolefin microfibers are present in a weight amount that is between about 5 to about 40 weight percent.
8. The biodisintegratable nonwoven material of Claim I, wherein the compatibilizer is an ethoxylated alcohol.
9. The biodisintegratable nonwoven material of Claim 1, wherein the thermoplastic composition exhibits a Receding Contact Angle value that is less than about 55 degrees.
10. The biodisintegratable nonwoven material of Claim 1, wherein the aliphatic polyester polymer is selected from the group consisting of poly(lactic acid), polybutylene succinate, polybutylene succinate-co-adipate, polyhydroxybutyrate-co- valerate, polycaprolactone, sulfonated polyethylene terephthalate, mixtures of such polymers, and copolymers of such polymers; wherein the polyolefin is selected from the group consisting of _ homopolymers and copolymers comprising repeating units selected from the group consisting of ethylene, propylene, butene, pentene,

hexene, heptene, octene, 1,3 -butadiene, and 2-methyl-1,3 - butadiene and the polyolefin microfibers are present in a weight amount that is between about 5 to about 40 weight percent; the compatibilizer is an ethoxylated alcohol; and the thermoplastic composition exhibits a Receding Contact Angle value that is less than about 55 degrees.
11. The biodisintegratable nonwoven material of Claim 10, wherein the aliphatic polyester polymer is poly(lactic acid) and the polyolefin is selected from the group consisting of polyethylene and polypropylene.
12. A biodisintegratable nonwoven material comprising a plurality of multicomponent fibers, wherein the multicomponent fibers are prepared from a thermoplastic composition, wherein the thermoplastic composition comprises:

a. an aliphatic polyester polymer in a weight amount that is between about 45 to about 90 weight percent, wherein the aliphatic polyester polymer forms a substantially continuous phase;

b. polyolefin microfibers in a weight amount that is between greater than 0 to about 45 weight percent, wherein the polyolefin microfibers have a diameter that is less than about 50 micrometers and the polyolefin microfibers form a substantially discontinuous phase encased within the aliphatic polyester polymer substantially continuous phase; and

C. a compatibilizer, which exhibits a hydrophilic- lipophilic balance ratio that is between about 10 to about 40, in a weight amount that is between about 7 to about 25 weight percent, wherein all weight percents are based on the total weight amount of the aliphatic polyester polymer; the polyolefin microfibers, and the compatibilizer present in the thermoplastic composition. wherein the multicomponent fiber exhibits a Receding Contact Angle value that is less than about 55 degrees.
13. The biodisintegratable nonwoven material of Claim 12, wherein the multicomponent fiber exhibits a Heat Shrinkage value that is less than about 10 percent.
14. The biodisintegratable nonwoven material of Claim 12, wherein the aliphatic polyester polymer is selected from the group consisting of poly(lactic acid), polybutylene succinate, polybutylene succinate-co-adipate, polyhydroxybutyrate-co- valerate, polycaprolactone, sulfonated polyethylene terephthalate, mixtures of such polymers, and copolymers of such polymers.
15. The biodisintegratable nonwoven material of Claim 14, wherein the aliphatic polyester polymer is poly(lactic acid).
16. The biodisintegratable nonwoven material of Claim 12, wherein the polyolefin is selected from the group consisting of homopolymers and copolymers comprising repeating units selected from the group consisting of ethylene, propylene, butene, pentene, hexene, heptene, octene, 1,3 -butadiene, and 2-methyl-1,3 - butadiene.
17. The biodisintegratable nonwoven material of Claim ‘16, wherein the polyolefin is selected from the group consisting of polyethylene and polypropylene.
18. The biodisintegratable nonwoven material of Claim 12, wherein the polyolefin microfibers have a diameter that is less than about 25 micrometers.
19. The biodisintegratable nonwoven material of Claim 12, wherein the polyolefin microfibers are present in a weight amount that is between about 5 to about 40 weight percent.
20. The biodisintegratable nonwoven material of Claim 12, wherein the compatibilizer is an ethoxylated alcohol.
21. The biodisintegratable nonwoven material of Claim 12, wherein the aliphatic polyester polymer is selected from the group consisting of poly(lactic acid), polybutylene succinate, polybutylene succinate-co-adipate, polyhydroxybutyrate-co- valerate, polycaprolactone, sulfonated polyethylene terephthalate, mixtures of such polymers, and copolymers of such polymers; wherein the polyolefin is selected from the group consisting of homopolymers and copolymers comprising repeating units selected from the group consisting of ethylene, propylene, butene, pentene, hexene, heptene, octene, 1,3 -butadiene, and 2-methyl-1,3 - butadiene and the polyolefin microfibers are present in a weight amount that is between about 5 to about 40 weight percent; the compatibilizer is an ethoxylated alcohol; and the multicomponent fiber exhibits a Heat Shrinkage value that is less than about 10 percent.
22. The biodisintegratable nonwoven material of Claim 21, wherein the aliphatic polyester polymer is poly(lactic acid) and the polyolefin is selected from the group consisting of polyethylene and polypropylene.
23. A biodisintegratable nonwoven material comprising a plurality of multicomponent fibers, wherein the multicomponent fibers are prepared from a plurality of components, further wherein one of the components comprises an unreacted thermoplastic mixture comprising:

a. an aliphatic polyester polymer in a weight amount that is between about 45 to about 90 weight percent, wherein the aliphatic polyester polymer forms a substantially continuous phase;

b. polyolefin microfibers in a weight amount that is between greater than 0 to about 45 weight percent, wherein the polyolefin microfibers have a diameter that is less than about 50 micrometers and the polyolefin microfibers form a substantially discontinuous phase encased within the aliphatic polyester polymer substantially continuous phase; and

C. a compatibilizer, which exhibits a hydrophilic- lipophilic balance ratio that is between about 10 to about 40, in a weight amount that is between about 7 to about 25 weight percent, wherein all weight percents are based on the total weight amount of the aliphatic polyester polymer; the polyolefin microfibers, and the compatibilizer present in the thermoplastic composition; wherein the plurality of multicomponent fibers are arranged in a configuration such that the unreacted thermoplastic component is located at a surface of the multicomponent fiber.
24. The biodisintegratable nonwoven maternal of Claim 23, wherein the configuration is selected from sheath-core, segmented pie shape, eccentric sheath-core, side-by-side, or multicomponent trilobal.
25. The biodisintegratable nonwoven material of Claim 23, wherein the multicomponent fiber exhibits a Heat Shrinkage value that is less than about 10 percent.
26. The biodisintegratable nonwoven material of Claim 23, wherein the aliphatic polyester polymer is selected from the group consisting of poly(lactic acid), polybutylene succinate, polybutylene succinate-co-adipate, polyhydroxybutyrate-co- valerate, polycaprolactone, sulfonated polyethylene terephthalate, mixtures of such polymers, and copolymers of such polymers.
27. The biodisintegratable nonwoven material of Claim 23, wherein the polyolefin is selected from the group consisting of homopolymers and copolymers comprising repeating units selected from the group consisting of ethylene, propylene, butene, pentene, hexene, heptene, octene, 1,3 -butadiene, and 2-methyl-1,3 - _ butadiene.
28. The biodisintegratable nonwoven material of Claim 23, wherein the polyolefin microfibers have a diameter that is less than about 25 micrometers.
29. The biodisintegratable nonwoven material of Claim 23, wherein the polyolefin microfibers are present in a weight amount that is between about 5 to about 40 weight percent.
30. The biodisintegratable nonwoven material of Claim 23, wherein the aliphatic polyester polymer is selected from the group consisting of poly(lactic acid), polybutylene succinate, polybutylene succinate-co-adipate, polyhydroxybutyrate-co- valerate, polycaprolactone, sulfonated polyethylene terephthalate, mixtures of such polymers, and copolymers of such polymers; wherein the polyolefin is selected from the group consisting of homopolymers and copolymers comprising repeating units selected from the group consisting of ethylene, propylene, butene, pentene, hexene, heptene, octene, 1,3 -butadiene, and 2-methyl-1,3 - butadiene and the polyolefin microfibers are present in a weight amount that is between about 5 to about 40 weight percent: the compatibilizer is an ethoxylated alcohol; and the multicomponent fiber exhibits a Heat Shrinkage value that is less than about 10 percent.
31. A biodisintegratable nonwoven material comprising a plurality of multicomponent fibers, wherein the multicomponent fibers exhibit a Receding Contact Angle value that is less than about 55 degrees.
32. A disposable absorbent product comprising a liquid- permeable topsheet, a fluid acquisition layer, an absorbent structure, and a liquid-impermeable backsheet, wherein at least one of the liquid-permeable topsheet, the fluid acquisition layer, or the liquid-impermeable backsheet comprises a biodisintegratable nonwoven material comprising a plurality of multicomponent fibers prepared from a thermoplastic composition, wherein the thermoplastic composition comprises:

a. an aliphatic polyester polymer in a weight amount that is between about 45 to about 90 weight percent, wherein the aliphatic polyester polymer forms a substantially continuous phase;

b. polyolefin microfibers in a weight amount that 1s between greater than O to about 45 weight percent, wherein the polyolefin microfibers have a diameter that is less than about 50 micrometers and the polyolefin microfibers form a substantially discontinuous phase encased within the aliphatic polyester polymer substantially continuous phase; and

Cc. a compatibilizer, which exhibits a hydrophilic- lipophilic balance ratio that is between about 10 to about 40, in a weight amount that is between about 7 to about 25 weight percent, wherein all weight percents are based on the total weight amount of the aliphatic polyester polymer; the polyolefin microfibers, and the compatibilizer present in the thermoplastic composition. wherein the multicomponent fiber exhibits a Receding Contact Angle value that is less than about 55 degrees.
33. The" disposable absorbent product of Claim 32, wherein the multicomponent fiber exhibits a Heat Shrinkage value that is less than about 10 percent.
34. The disposable absorbent product of Claim 32, wherein the aliphatic polyester polymer is selected from the group consisting of poly(lactic acid), polybutylene succinate, polybutylene succinate-co-adipate, polyhydroxybutyrate-co- valerate, polycaprolactone, sulfonated polycthylene terephthalate, mixtures of such polymers, and copolymers of such polymers.
35. The disposable absorbent product of Claim 34, — wherein the aliphatic polyester polymer is poly(lactic acid).
36. The disposable absorbent product of Claim 32, wherein the polyolefin is selected from the group consisting of homopolymers and copolymers comprising repeating units selected from the group consisting of ethylene, propylene, butene, pentene, hexene, heptene, octene, 1,3 -butadiene, and 2-methyl-1,3 - butadiene.
37. The disposable absorbent product of Claim 36, wherein the polyolefin is selected from the group consisting of polyethylene and polypropylene.
38. The disposable absorbent product of Claim 32, wherein the polyolefin microfibers have a diameter that is less than about 25 micrometers.
39. The disposable absorbent product of Claim 32, wherein the polyolefin microfibers are present in a weight amount that 1s between about 5 to about 40 weight percent.
40. The disposable absorbent product of Claim 32, wherein the compatibilizer is an ethoxylated alcohol.
41. The disposable absorbent product of Claim 32, wherein the aliphatic polyester polymer is selected from the group consisting of poly(lactic acid), polybutylene succinate, polybutylene succinate-co-adipate, polyhydroxybutyrate-co- valerate, polycaprolactone, sulfonated polyethylene terephthalate, mixtures of such polymers, and copolymers of such polymers; wherein the polyolefin is selected from the group consisting of homopolymers and copolymers comprising repeating units selected from the group consisting of ethylene, propylene, butene, pentene, hexene, heptene, octene, 1,3 -butadiene, and 2-methyl-1,3 - butadiene and the polyolefin microfibers are present in a weight amount that is between about 5 to about 40 weight percent; the compatibilizer is an ethoxylated alcohol; and the multicomponent fiber exhibits a Heat Shrinkage value that is less than about 10 percent.
42. The disposable absorbent product of Claim 41, wherein the aliphatic polyester polymer is poly(lactic acid) and the polyolefin is selected from the group consisting of polyethylene and polypropylene.
43. The disposable absorbent product of Claim 32, wherein the liquid-permeable topsheet, the fluid acquisition layer, and the liquid-impermeable backsheet comprise the biodisintegratable nonwoven material comprising a plurality of multicomponent fibers prepared from the thermoplastic composition. :
44. A disposable absorbent product comprising a liquid- permeable topsheet, an absorbent structure, and a liquid- impermeable backsheet, wherein at least one of the liquid- permeable topsheet or the hiquid-impermeable backsheet comprises a biodisintegratable nonwoven material comprising a plurality of multicomponent fibers prepared from a thermoplastic composition, wherein the thermoplastic composition comprises:

a. an aliphatic polyester polymer in a weight amount that is between about 45 to about 90 weight percent, wherein the aliphatic polyester polymer forms a substantially continuous phase;

b. polyolefin microfibers in a weight amount that 1s between greater than 0 to about 45 weight percent, wherein the polyolefin microfibers have a diameter that is less than about 50 micrometers and the polyolefin microfibers form a substantially discontinuous phase encased within the aliphatic polyester polymer substantially continuous phase; and

C. a compatibilizer, which exhibits a hydrophilic- _ lipophilic balance ratio that is between about 10 to about 40, in a weight amount that is between about 7 to about 25 weight percent,

wherein all weight percents are based on the total weight amount of the aliphatic polyester polymer; the polyolefin microfibers, and the compatibilizer present in the thermoplastic composition. wherein the multicomponent fiber exhibits a Receding Contact Angle value that is less than about 55 degrees.
45. The disposable absorbent product of Claim 44, wherein the multicomponent fiber exhibits a Heat Shrinkage value that is less than about 10 percent.
46. The disposable absorbent product of Claim 44, wherein the aliphatic polyester polymer is selected from the group consisting of poly(lactic acid), polybutylene succinate, polybutylene succinate-co-adipate, polyhydroxybutyrate-co- valerate, polycaprolactone, sulfonated polyethylene terephthalate, mixtures of such polymers, and copolymers of such polymers.
47. The disposable absorbent product of Claim 46, wherein the aliphatic polyester polymer is poly(lactic acid).
48. The disposable absorbent product of Claim 44, wherein the polyolefin is selected from the group consisting of homopolymers and copolymers comprising repeating units selected from the group consisting of ethylene, propylene, butene, pentene, hexene, heptene, octene, 1,3 -butadiene, and 2-methyl-1,3 - butadiene.
49. The disposable absorbent product of Claim 48, wherein the polyolefin is selected from the group consisting of polyethylene and polypropylene.
50. The disposable absorbent product of Claim 44, wherein the polyolefin microfibers have a diameter that is less than about 25 micrometers.
S1. The disposable absorbent product of Claim 44, wherein the polyolefin microfibers are present in a weight amount that is between about 5 to about 40 weight percent.
52. The disposable absorbent product of Claim 44, wherein the compatibilizer is an ethoxylated alcohol.
53. The disposable absorbent product of Claim 44, wherein the aliphatic polyester polymer is selected from the group consisting of poly(lactic acid), polybutylene succinate, polybutylene succinate-co-adipate, polyhydroxybutyrate-co- valerate, polycaprolactone, sulfonated polyethylene terephthalate, mixtures of such polymers, and copolymers of such polymers; wherein the polyolefin is selected from the group consisting of homopolymers and copolymers comprising repeating units selected from the group consisting of ethylene, propylene, butene, pentene, hexene, heptene, octene, 1,3 -butadiene, and 2-methyl-1,3 - butadiene and the polyolefin microfibers are present in a weight amount that is between about 5 to about 40 weight percent; the compatibilizer is an ethoxylated alcohol; and the multicomponent fiber exhibits a Heat Shrinkage value that is less than about 10 percent.
54. The disposable absorbent product of Claim 53, wherein the aliphatic polyester polymer is poly(lactic acid) and the polyolefin is selected from the group consisting of polyethylene and polypropylene.
55. The disposable absorbent product of Claim 44, wherein the liquid-permeable topsheet and the liquid-impermeable backsheet comprise the biodisintegratable nonwoven material comprising a plurality of multicomponent fibers prepared from the thermoplastic composition. _
56. A disposable absorbent product comprising a liquid- permeable topsheet, a fluid acquisition layer, an absorbent structure, and a liquid-impermeable backsheet, wherein at least one of the liquid-permeable topsheet, the fluid acquisition layer, or the liquid-impermeable backsheet comprises a biodisintegratable nonwoven material comprising a plurality of multicomponent fibers prepared from a thermoplastic composition, wherein the multicomponent fiber exhibits a Receding Contact Angle value that is less than about 55 degrees.
57. A biodisintegratable nonwoven material substantially as herein described and exemplified.
58. A disposable absorbent product substantially as herein described and exemplified. AMENDED SHEET - DATED 24 MARCH 2003