MXPA02001354A

MXPA02001354A - Biodisintegratable nonwovens with fluid management properties and disposable absorbent products containing same.

Info

Publication number: MXPA02001354A
Application number: MXPA02001354A
Authority: MX
Inventors: Tsai Fu-Jya
Original assignee: Kimberly Clark Co
Priority date: 1999-08-25
Filing date: 2000-08-16
Publication date: 2002-07-22
Also published as: KR20020029110A; AU772567B2; EP1218575A1; WO2001014621A1; RU2002107430A; CN1382234A; BR0013573A; KR100714953B1; AR025407A1; AU7760100A; JP2003507596A

Abstract

Disclosed is a biodisintegratable nonwoven material having improved fluid management properties. The biodisintegratable nonwoven material demonstrates a 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. The nonwoven material may be produced using thermoplastic compositions which 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 and good wettability 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.

Description

NON-WOVEN BIENESINTEGRABLES WITH IMPROVED FLUID-HANDLING PROPERTIES AND DISPOSABLE ABSORBENT PRODUCTS CONTAINING THE SAME FIELD OF THE INVENTION The present invention relates to a disposable absorbent product having a biodegradable, nonwoven material having improved fluid handling properties. The nonwoven material can be produced from polymer blends. These mixtures can include multicomponent fibers. These multicomponent fibers comprise an unreacted mixture of an aliphatic polyester polymer as a continuous phase, of polyolefin microfibers as a discontinuous phase enclosed within the continuous phase of aliphatic polyester polymer and of a compatibilizer for the aliphatic polyester polymer and polyolefin microfibers. The multicomponent fiber exhibits substantial biodegradable properties but nevertheless it is easily processed. The biodegradable nonwoven materials can be used in a disposable absorbent product that is 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 infant and child care areas, diapers and underpants have generally replaced reusable fabric absorbent articles. Other typical disposable absorbent products include women's care products such as sanitary napkins or tampons, adult incontinence products, and health care products such as surgical covers or wound dressings. A typical disposable absorbent product generally comprises a composite structure that includes a liquid permeable topsheet, a fluid acquisition layer, an absorbent structure, and a liquid impervious backsheet. These products usually include some type of fastening system to adjust the product on the user.

Disposable absorbent products are typically subjected to one or more discharges of liquid such as water, urine, menstrual fluids or blood, during use. As such, the outer cover materials of the disposable absorbent products are typically made of liquid impervious and liquid insoluble materials, such as polypropylene films, which exhibit a handling capacity.

It has sufficient strength and resistance so that the disposable absorbent products retain their integrity during use by a user and do not allow runoff of the liquid discharged into the product.

Although current disposable baby diapers and other disposable absorbent products have generally been accepted by the public, these products still have a need for improvement in specific areas. For example, many disposable absorbent products can be difficult to discard. For example, attempts to discard with water discharge many disposable absorbent products in a toilet to a drainage system typically lead to blockage of the toilet or of the pipes connecting the toilet to the drainage system. In particular, the outer cover materials typically used in the disposable absorbent products generally do not disintegrate or disperse when disposed of with flushing in a toilet so that the disposable absorbent product can not be disposed of in this manner. If the outer cover materials become too thin in order to reduce the overall blockage of the disposable absorbent product to reduce the possibility of blocking a toilet or drainage pipe, then the outer cover material will typically not exhibit sufficient strength. to avoid tearing or breaking when the outer covering material is subjected to the stresses of normal use by a user.

In addition, the disposal of solid waste is becoming a growing concern in the world. As the landfill continues to fill, there has been an increasing demand for a reduction in the source of material in disposable products, the incorporation of more recyclable and / or degradable components into disposable products, and the design of products that can be disposed of by means other than the incorporation into solid waste disposal facilities such as landfills.

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

Even when 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 so that the fibers usually suffer severe heat shrinkage due to to polymer chain relaxation during downstream heat treatment processes such as lamination or thermal bonding.

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 are typically hydrophobic and as 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, leakage or permanence, and toxicity. In addition, polyolefin fibers are not generally biodegradable or compostable.

It would therefore be desirable to prepare a biodegradable disintegrable nonwoven material which includes fibers that exhibit the thermal dimensional stability of polyolefin materials but which are nonetheless essentially biodegradable and also wettable in the use of surfactants. A simple solution to that desire will 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 require to be chemically compatible, so that the components effectively adhere to each other, and have similar rheological characteristics, so that the multicomponent fiber exhibits minimal strength and other processing properties. and mechanical. It has therefore proved to be a challenge for art experts to combine the components that fulfill these basic processing needs as well as to satisfy the The desire for the complete multicomponent fiber to be effectively and essentially degradable and hydrophilic.

It is therefore desirable to provide a biodegradable nonwoven material which includes the fibers of 15 multicomponents which are essentially degradable in the environment. It is also desirable to provide an essentially degradable multicomponent fiber which has good thermal dimensional stability and is hydrophilic without the substantial use of the surfactants. Finally, it is also desirable 20 providing a biodegradable non-woven material having an essentially degradable multi-component fiber which is easily and efficiently prepared and which is suitable for use in the preparation of these biodegradable nonwoven materials. 25 ^ & SYNTHESIS OF THE INVENTION The present invention relates to a non-woven biodegradable material which is essentially biodegradable and which, however, is easily prepared and easily processed into desired final structures.

One aspect of the present invention relates to a biodegradable nonwoven material which includes a thermoplastic composition comprising a mixture of a first component, a second component and a third component.

An incorporation of such a thermoplastic composition comprises an unreacted mixture of an aliphatic polyester polymer as an essentially continuous phase, of polyolefin microfibers as an essentially discontinuous phase enclosed within the essentially continuous phase of aliphatic polyester polymer, and a compatibilizer for the aliphatic polyester polymer and polyolefin microfibers.

In another aspect, the present invention relates to a biodegradable nonwoven material which includes a multi-component fiber which is essentially degradable and which is nevertheless easily prepared and easily processable into desired end structures.

An aspect of the present invention relates to a non-woven biodegradable material which includes a multi-component fiber comprising an unreacted mixture of an aliphatic polyester polymer as an essentially continuous, polyolefin microfibers as an essentially discontinuous phase enclosed within an essentially continuous phase of aliphatic polyester polymer, and a compatibilizer for the aliphatic polyester polymer and polyolefin microfibers.

One embodiment of such a non-woven structure is a useful fluid acquisition layer in a disposable absorbent product.

One aspect of the present invention relates to a multicomponent fiber that includes an unreacted thermoplastic blend of an aliphatic polyester polymer as an essentially continuous phase, the polyolefin microfibers as an essentially discontinuous phase enclosed within the essentially continuous polymer phase. of aliphatic polyester, and a compatibilizer for the aliphatic polyester polymer and the polyolefin microfibers as a component of the multicomponent fiber. The fiber can be in any configuration so that the thermoplastic blend is exposed to the fiber surface as in a sheath / core, an eccentric sheath / core, in a side-by-side configuration or any other configuration. Such fibers can be made in any type of nonwoven material.

In another aspect, the present invention relates to a disposable absorbent product comprising the biodegradable nonwoven material described therein.

In another aspect, the present invention relates to a process for preparing the biodegradable nonwoven material described therein.

DETAILED DESCRIPTION OF THE INVENTION The present invention is directed to a disposable absorbent product having a biodegradable nonwoven material which demonstrates superior contact angle hysteresis, faster absorption times, and improved skin dryness compared to the nonwoven materials of the prior art. . In addition, these biodegradable nonwoven materials also exhibit high wetting rates, which is unexpected based on higher hysteresis values.

These biodegradable, 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 essentially returns to its original composition when cooled to room temperature.

It has been found that, by using an unreacted mixture of an aliphatic polyester polymer as an essentially continuous phase, the polyolefin microfibers as a discontinuous phase essentially embedded within the essentially continuous phase of the aliphatic polyester polymer, and a compatibilizer for the aliphatic polyester polymer and the polyolefin microfibers, a thermoplastic composition can be prepared wherein such a thermoplastic composition is essentially degradable however, whose thermoplastic composition is easily processable in nonwoven structures exhibiting 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 be a polylactic acid.The 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 can also be prepared by the polymerization of lactide.As such, as used herein, the term "poly (lactic acid) polymer" is intended representing the polymer that is prepared by either the polymerization of lactic acid or lactide.

Lactic acid and lactide are known to be asymmetric molecules, having two mentioned optical isomers, respectively, such as the levorotatory enantiomer (hereinafter referred to as "L") and the dextrorotatory enantiomer (hereinafter referred to as "D"). "). As a result, by polymerization of a particular enantiomer or by using a mixture of two enantiomers, it is possible to prepare different polymers that are chemically similar but which have different 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 melt temperature, the melt rheology and the crystallinity of the polymer. By being able to control such properties, it is possible to prepare a multicomponent fiber that exhibits the desired melt strength, . ^^^ mechanical properties, smoothness and processability properties to be able to manufacture 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 the desired properties. The aliphatic polyester polymer will be present in the thermoplastic composition in an amount by weight that is less than 100 percent by weight, beneficially from about 45 percent by weight to about 90 percent by weight, suitably from around from 50 percent by weight to about 88 percent by weight, and more suitably from about 55 percent by weight to about 70 percent by weight, where all percentages by weight are based on the amount of weight total of the aliphatic polyester polymer, the polyolefin microfiber, and the compatibilizer present in the thermoplastic composition. The composition ratio of the three components in the thermoplastic composition is generally important to maintain the substantial biodegradability of the thermoplastic composition because the aliphatic polyester polymer generally requires being in an essentially continuous phase in order to maintain access to the biodegradable of the thermoplastic composition. An approximation of the limits of the proportions of components can be determined based on the densities of the components. The density of each component is converted to a volume (assume 100 grams of each component), the volumes of the components are aggregated together for a volume of total thermoplastic composition and the weight averages of the components are calculated to establish the approximate minimum proportion of each component necessary to produce a thermoplastic composition with a volumetric majority of the aliphatic polyester polymer in the mixture.

It is generally desired that the aliphatic polyester polymer exhibits a weight average molecular weight that is effective for the thermoplastic composition to exhibit the desirable melt strength., the mechanical strength of fiber and the properties of fiber spinning. In general, if the weight average molecular weight of an aliphatic polyester polymer is very high, this represents that the polymer chains are heavily entangled which can result in a thermoplastic composition comprising the aliphatic polyester polymer that is difficult to process . Conversely, if the weight average molecular weight of an aliphatic polyester polymer is very low, this represents that the polymer chains are not sufficiently entangled which can result in a thermoplastic composition comprising that the aliphatic polyester polymer exhibits a Relatively weak melt strength, making high-speed processing difficult. Thus, aliphatic polyester polymers suitable for use in the present invention exhibit average molecular weight weights that are beneficially between about 10,000 to about 2,000,000, more beneficially 5 of between about 50,000 to about 400,000 and suitably from around 100,000 to around 300,000. The weight average molecular weight for the polymers or for the polymer blends can be determined using a method as described in the test methods section given here.

It is also desired that the aliphatic polyester polymer exhibit a polydispersity index value that is effective for the thermoplastic composition to exhibit the 15 desirable melt strength, fiber mechanical strength and fiber spinning properties. As used herein, the "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. 20 polymer. In general, if the polydispersity index value of an aliphatic polyester polymer is very high, a thermoplastic composition comprising that aliphatic polyester polymer can be difficult to process due to the inconsistent processing properties caused by segments of Polymer comprising low molecular weight polymers that have lower melt strength properties during spinning. Therefore, it is desired that the aliphatic polyester polymer exhibit a polydispersity index value that is beneficially from about 1 to about 15, more beneficially from about 1 to about 4, and suitably from about from 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 given herein.

In the present invention, it is desired that the aliphatic polyester polymer be biodegradable. As a result of this, the nonwoven material including the aliphatic polyester polymer will be essentially degradable when disposed in the environment and exposed to air and / or water. How I know 15 used here, "biodegradable" is meant to represent that a material degrades from the action of naturally occurring microorganisms such as bacteria, fungi and algae. The use of biodegradable materials allows the formation of biodegradable materials. As used here, the term "Biodegradable" is intended to represent that a part of the nonwoven material biodegrades, leaving a quantity of material that is not capable of being seen by the eye without help.

In the present invention, it is also desirable that The aliphatic polyester polymer is compostable. As a result of this, the nonwoven material that includes the polymer asa - »* -" -a ^ nm ^ "of aliphatic polyester will essentially be compostable when disposed of in the environment and exposed to air and / or water.As used herein," compostable "means that the material is capable of undergoing biological decomposition at a composting 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 are polyolefin microfibers. Polyolefins are known to those skilled in the art. Any polyolefin capable of being manufactured in an article, such as a microfiber, is believed to be suitable for use in the present invention. Examples of polyolefins suitable for use in the present invention are 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 of low or high density or may be generally straight chain or branched polymers. The methods for forming the 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 "hydrophobic" 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 can be determined as set forth in the work of Robert J. Good and Robert J. Stromberg, editions in "Surface and Science of Colloid - Experimental Methods," Volume 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 from about 1 gram per 10 minutes to about 200 grams per 10 minutes, suitably from about 10 grams per 10 minutes. minutes to around 100 grams for 10 minutes, and more appropriately from around 20 grams for 10 minutes at around 40 grams per 10 minutes.

The melt flow rate of a material can be determined according to Test Method ASTM D1238-E incorporated herein in its entirety 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 microns, beneficially less than about 25 microns, more beneficially less than about 10 microns. micrometers, suitably less than about 5 micrometers, and more adequately 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 multi-component fiber prepared from the thermoplastic composition of the present invention is effective for the multicomponent fiber to exhibit the desirable melt strength. , the mechanical strength of fiber and the properties of fiber spinning. In general, if the polyolefin microfiber comprises a percentage of the cross-sectional area of a multicomponent fiber that is very high, this generally results in a non-woven material that will not be essentially biodegradable 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 very low, this generally results in a non-woven material that will not exhibit effective structural properties or that may be difficult to process. Therefore, 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 multi-component fiber, even 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 "fibers" or "fibrous" is meant to refer to a material wherein the length-to-diameter ratio of such material is greater than about 10. Inverse form, a "non-fiber" material or "non-fibrous" is meant to refer to a material in which the length-to-diameter ratio of such material is about 10 or less.

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

It is generally desired that the polyolefin microfibers are present in the thermoplastic composition in an amount effective to result in the thermoplastic composition exhibiting the desired properties. The polyolefin microfibers will be present in the thermoplastic composition in an amount by weight that is beneficially from more than 0 percent by weight to about 45 percent by weight, suitably within about 5 percent by weight to about 40 percent by weight. percent by weight, and more suitably within about 10 percent by weight to about 30 percent by weight, wherein all percents by weight are based on the total weight amount of the aliphatic polyester polymer, the polyolefin microfiber and of the compatibilizer present in the thermoplastic composition. It is generally important that the polyolefin be of an essentially 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 adversely affecting the biodegradability of the aliphatic polyester or 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 the prepared nonwoven materials of the thermoplastic composition, are generally hydrophilic so that such materials are useful in the disposable absorbent products which are subject to the discharge of liquids. watery such as water, urine, menstrual or blood fluids. Therefore, it has been found that it is 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 processing 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 adversely 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 to prepare as an essentially homogeneous mixture by itself. Generally, then, it has been found that it is desirable to use a compatibilizer to aid in the effective preparation and processing of the aliphatic polyester polymer and polyolefin microfibers in a single thermoplastic composition.

Therefore, the third component in the thermoplastic composition is a compatibilizer for the aliphatic polyester polymer and the polyolefin microfibers. Suitable compatibilizers for use in the present invention will generally comprise a hydrophilic section which will generally be compatible with the aliphatic polyester polymer and the hydrophobic section which will generally be compatible with polyolefin microfibers. These hydrophilic and hydrophobic sections generally exist in separate blocks so that the overall compatibilizer structure can be a random block or di-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 serve as a surfactant in a processed material of the thermoplastic composition, the non-woven material of the present invention, by modifying the contact angle of the water in air of the processed material. The hydrophobic part of the compatibilizer may be, but is not limited to a polyolefin such as polyethylene or polypropylene. The hydrophilic part of the compatibilizer may contain ethylene oxide, ethoxylates, glycols, alcohols or any combination thereof. Examples of suitable compatibilizers include the ethoxylated alcohols UNITHOX® 480 and UNITHOX® 750, or the acidic amide ethoxylates UNICID®, 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 strength, and fiber spin properties. In general, if the average molecular weight of The weight of a compatibilizer is too high, the compatibilizer will not mix well with the other components in the thermoplastic composition because the viscosity of the compatibilizer will be too high so that it lacks the mobility necessary for mixing. Conversely, if the weight average molecular weight of the compatibilizer is very low, this represents that the compatibilizer will generally not mix well with the other components and will have such low viscosity that it will cause processing problems. Thus, suitable compatibilizers for use in the present invention will exhibit average molecular weight weights that are beneficially within about 1,000 to 100,000, suitably from about 1,000 to about 50,000 and more suitably from 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 is generally desired that the compatibilizer exhibit an effective hydrophilic-lipophilic balance ratio (HLB relation). The hydrophilic-lipophilic balance ratio of i, i. & nt -1. a material describes the relative relationship of the hydrophilicity of the material. The hydrophilic-lipophilic balance ratio is calculated as the weight average molecular weight of the hydrophilic part divided by the average molecular weight of the total weight of the material, whose value is then multiplied by 20. If the value of the hydrophilic balance ratio- Lipophilic is very low, the material will not generally provide the desired improvement in hydrophilicity. Conversely, if the value of the hydrophilic-lipophilic balance ratio is very high, the material will generally not be mixed in the thermoplastic composition due to chemical incompatibility and differences in viscosities with other components. Thus, compatibilizers useful in the present invention exhibit hydrophilic-lipophilic balance ratio values that are beneficially from about 10 to about 40, suitably from about 10 to about 20, and more suitably from about 12 to around 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 the desired properties. In general, a minimum amount of the compatibilizer will be required to achieve effective mixing and processing with 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 an amount by weight that is beneficially between about 3 percent by weight to about 25 percent by weight, more beneficially of between about 10 percent by weight to about 25 percent by weight. percent by weight, suitably from about 12 percent by weight to about 20 percent by weight, and more suitably from about 13 percent by weight to about 18 percent by weight, where all by the hundreds by weight are based on the total weight amount of the aliphatic polyester polymer, the polyolefin microfiber and the compatibilizer present in the thermoplastic composition.

Although the main components of the thermoplastic composition have been described above, such a thermoplastic composition is not limited thereto and may include other components not adversely affecting the desired properties of the resulting biodegradable nonwoven materials. The example materials which can be used as additional components will include, without limitation, the pigments, the antioxidants, the stabilizers, the surfactants, the waxes, the flow promoters, the solid solvents, the plasticizers, the nucleating agents, the particles and the aggregate materials to improve the processing 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 percent by weight, more beneficially less than about 3 percent by weight, and suitably less than about 1 percent by weight, wherein all percents by weight 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 is generally the morphology resulting from a mixture of the aliphatic polyester polymer, the polyolefin polymer, the compatibilizer, and optionally, any additional components. The polyolefin polymer forms an essentially discontinuous phase enclosed within the essentially continuous phase of aliphatic polyester polymer. In order to achieve the desired properties for the thermoplastic compositionIt is desirable that the aliphatic polyester polymer, the polyolefin microfibers, and the compatibilizer remain essentially 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 an essentially continuous phase and that the polyolefin microfibers ^^ m ^ gj form an essentially discontinuous phase, wherein the continuous phase of aliphatic polyester polymer essentially encloses the polyolefin microfibers within its structure. As used herein, the term "enclose" and related terms is intended to mean that the essentially continuous phase of the aliphatic polyester polymer essentially encloses or surrounds the polyolefin microfibers.

In an embodiment of the present invention, after dry blending together the aliphatic polyester polymer, the polyolefin polymer and the compatibilizer to form a dry blend of thermoplastic composition, such a dry blend of thermoplastic composition is beneficially stirred, or otherwise mixed to effectively effectively combine the aliphatic polyester polymer, the polyolefin polymer and the compatibilizer so that an essentially homogeneous dry blend is formed. The dry mix can then be melt blended in, for example, an extruder to effectively and uniformly mix the aliphatic polyester polymer, the polyolefin polymer and the compatibilizer so that an essentially homogenous melt mixture is formed. The essentially homogeneous molten mixture can then be cooled and pelletized. Alternatively, the essentially homogeneous molten mixture may be sent directly to a spin pack or other equipment to form fibers or a non-woven structure. 4 & amp; -,.

Alternate methods of mixing the components together 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 that is being used to mix the components together. In addition, it is also possible to initially mix all the components together at the same time. Other methods of mixing together the components of the present invention are also possible and will be readily recognized by one skilled in the art.

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

With the aliphatic polyester polymer forming the essentially continuous phase, the aliphatic polyester polymer will generally provide an exposed surface on at least a portion of the multi-component fiber that will generally allow thermal bonding of the multi-component fiber to other fibers which may be the same or different from the multi-component fiber. As a result of this, the multiple component fiber can then be used to form thermally bonded fibrous nonwoven structures such as a nonwoven fabric. Polyolefin microfibers in multi-component fiber will generally provide stiffness or fiber resistance of multiple components and, therefore, to any non-woven structure comprising multiple component fiber. In order to provide such strength or stiffness to the multi-component fiber, it is generally desired that the polyolefin microfibers be essentially continuous along the length of the multi-component fiber.

Typical conditions for thermal processing of the various components include using a cutoff rate that is beneficially within about 100 seconds "1 to about 10000 seconds" 1, more beneficially from about 500 seconds "1 to about 5000 seconds" 1, suitably from about 1000 seconds "1 to about 2000 seconds" 1, and more adequately to about 1000 seconds "1. Typical conditions for the thermal processing of 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 from around 175 ° C to around 250 ° C.

The methods for making multi-component fibers are well known and do not need to be described in detail here. The melt spinning of the polymers includes the production of a continuous filament, such as a filament bonded with spinning and non-continuous melting, such as short and basic staple fiber structures. To form a fiber bonded with spinning or meltblowing, generally, a thermoplastic composition is extruded and fed into the distribution system wherein the thermoplastic composition is introduced into a spinning organ plate. The spun fiber is then cooled, solidified and pulled by an aerodynamic system, to be formed into a conventional nonwoven. Meanwhile, to produce a short or basic cut fiber, rather than being directly formed into a non-woven structure the spun fiber is cooled, solidified and pulled, generally by means of a system of mechanical rolls to an intermediate filament diameter and It is collected. Subsequently, the fiber can be "cold-pulled" at a temperature below its softening temperature, to the desired finished fiber diameter and crimped or textured and cut to a desired fiber length.

The process of cooling an extruded thermoplastic composition to room temperature is usually achieved by blowing an air at room temperature or at an ambient temperature on the extruded thermoplastic composition. This may be referred to as cooling or supercooling because the change in temperature is usually greater than 100 ° C and more frequently greater than 150 ° C over a relatively short time frame such as in seconds.

The multi-component fibers can be cut into relatively short lengths, such as the basic fibers which generally have lengths in the range of about 25 to about 50 millimeters and short staple fibers which are even shorter and generally have lengths of less than about 18 millimeters. See, for example, U.S. Patent No. 4,789,592 issued to Taniguchi et al., And U.S. Patent No. 5,336,552 to Strack et al., Both of which are incorporated herein by reference in their whole.

The resulting multi-component fibers are desired to exhibit an improvement in hydrophilicity, evidenced by a decrease in the contact angle of water in the air. The contact angle of water in the air of a fiber sample can be measured as either a forward or reverse contact angle value due to the nature of the test procedure. The advance contact angle generally measures an initial response of a material to a liquid, such as water. The backward contact angle generally gives a measure of how a material will operate over the duration of a first discharge or exposure to a liquid, as well as the following discharges. A lower backward contact angle means that the material is becoming more hydrophilic during exposure to the liquid and that it will generally then be able to transport liquids more consistently. Receding contact angle data is used to establish the highly hydrophilic nature of a multi-component fiber of the present invention even when it is preferred that a decrease in the advancing contact angle of the multi-component fiber also occurs. .

Therefore, in one embodiment, it is desired that the thermoplastic composition or a multi-component fiber exhibit a Reverse 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 more suitably less than about 10 degrees, wherein the receding contact angle is determined by the method that is described in the section of test methods given here.

Typical aliphatic polyester-based materials often undergo heat shrinkage during downstream thermal processing. The heat shrinkage mainly occurs due to thermally induced chain relaxation of the polymer segments in the amorphous phase and in the incomplete crystalline phase. To overcome this problem, it is generally desirable to maximize the crystallization of the material before the joining phase so that the thermal energy goes directly to the melt rather than to allow chain relaxation and rearrange the incomplete crystal structure. The typical solution to this problem is to subject the material to a heat settling treatment. As such, when prepared materials, such as fibers, are subjected to heat settling upon reaching a bonding roll, the fibers will not shrink essentially because such fibers are already fully or completely oriented. The present invention alleviates the need for this additional processing step due to the morphology of the multi-component fiber. As discussed above, 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 non-woven material use a thermoplastic composition or a multi-component fiber which exhibits an amount of shrinkage as quantified by means of a Heat Shrink value, at a temperature of about 100 ° C. , which is beneficially less than about 10 percent, more beneficially less than about 5 percent, adequately less than about 2 percent, and more adequately less than about 1 percent, where the amount Shrinkage is based on 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 shrinkage a fiber exhibits can be determined is included in the test methods section included here.

The resulting thermoplastic composition and the multi-component fibers are used to form biodegradable materials or fabrics which exhibit an increase in the higher contact angle hysteresis values, in the faster absorption times for discharges, and in a dryness of Improved skin, while maintaining very high wetting rates.

The biodegradable nonwoven materials of the present invention are suitable for use in disposable products including disposable absorbent products including disposable absorbent products such as diapers, adult incontinent products, and bed pads; in catamenial devices such as sanitary napkins and plugs; and other absorbent products such as bibs, cleansers, wound dressings, and surgical coats or covers. Therefore, in another aspect, the present invention relates to a disposable absorbent product comprising the previously described nonwoven material.

In one embodiment of the present invention, the multi-component fibers are formed in a fibrous matrix for incorporation into a disposable absorbent product. A fibrous matrix may take the form of, for example, a fibrous non-woven fabric. Fibrous non-woven fabrics can be made completely from the multi-component fibers or they can be mixed with other fibers. The length of the fibers used may depend in particular on the end use contemplated. Where the fibers that are to be degraded in water such as, for example, in a toilet, are advantageous and the lengths are maintained at about 15 millimeters or down about 15 millimeters.

In an embodiment of the present invention, a disposable absorbent product is provided, which disposable absorbent product generally comprises a composite structure that includes a liquid pervious topsheet, a fluid acquisition layer, an absorbent structure, and a liquid impervious backsheet, wherein minus one of the liquid-permeable top sheet of the fluid acquisition layer or the liquid-impermeable backsheet comprises the non-woven material of the present invention. In some cases, it may be beneficial if all three of the upper sheet, the fluid acquisition layer and the backing sheet comprise the nonwoven material of the present invention.

In another embodiment, the disposable absorbent product may generally comprise a composite structure that includes a liquid-permeable topsheet, an absorbent structure, and a liquid-impermeable backsheet, wherein at least one of the liquid-permeable or topsheet. of the liquid impervious backing sheet comprises the non-woven material of the present invention.

In another embodiment of the present invention, the non-woven material can be prepared on a spinning line. The resin pellets comprising the thermoplastic materials previously described are formed and pre-dried. Afterwards, these are fed to a single extruder. The fibers can be pulled through a fiber pulling unit (FDU) or an air pulling unit on a forming wire and can be thermally bonded. However, other preparation methods and techniques may also be used.

The disposable absorbent products of examples are generally described in the patents of the States United States of America Nos. A-4,710,187; A-4,762,521; A-4, 770, 656, - and A-4, 798, 603; whose references are incorporated here by this mention.

Absorbent products and structures according to all aspects of the present invention are generally subjected, during use, to multiple discharges of a body fluid. Thus, absorbent products and structures are desirably capable of absorbing multiple discharges of body fluids in amounts to which absorbent products and structures will be exposed during use. The discharges are generally separated from each other for a period of time.

- • ^? ^ Ataa TEST METHODS Fusion 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 equipped with a liquid nitrogen cooling accessory and was used in combination with the Thermal Analyst 2200 analysis program (version 8.10) both available from TA Instruments Inc., of New Castle, Delaware, was used for the determination of melting temperatures.

The samples of material tested were either in the form of fibers or pellets of resin. It was preferred not to handle the samples of material directly, but rather to use tweezers or other tools, so as not to introduce anything that could produce erroneous results. The samples of material were cut, in the case of fibers, or placed, in the case of resin pellets, in an aluminum tray and weighed to an accuracy of 0.01 milligrams on an analytical balance. If necessary, a lid can be folded over the sample of material in the tray.

The differential scanning calorimeter was calibrated using an indium metal standard and a baseline correction was performed, as described in the manual for the differential scanning calorimeter. A sample of material was placed in the test chamber of the differential scanning calorimeter for the test and an empty tray was used as a reference. All tests were run at 55 cubic centimeters / minute of nitrogen purge (industrial class) on the test chamber. The heating and cooling program was a two-cycle test that started with the chamber equilibrium at -75 ° C, followed by a heating cycle of 20 ° C / minute at 220 ° C, followed by a cooling cycle at 20 ° C / minute at -75 ° C and then another heating cycle at 20 ° C / minute at 220 ° C.

The results were evaluated using the analysis program where the transition temperature of the glass (Tg) of inflection, endothermic and exothermic peaks were identified and quantified. The transition temperature of the glass was identified as the area on the line where a different change in inclination occurs and then the melting temperature is determined using an automatic inflection calculation.

Apparent viscosity A capillary rheometer, under the designation of capillary rheometer Gottfer Rheograph 2003, which was used in combination with a WinRHEO analysis program (version 2.31), both available from Gottfried Company of Rock Hill, South Carolina, was used to evaluate the rheological properties of apparent viscosity of the material samples. The capillary rheometer placement included a 2000-bar pressure transducer and a round-hole capillary array 30 millimeters long / 30 millimeters active length / 1 millimeter diameter / 0 millimeters height / 180 degrees angled run.

If the sample of material being tested showed or was known to have a sensitivity to water, the material sample was dried in a vacuum oven above its glass transition temperature, for example, 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 and the pressure transducer was calibrated, the material sample was incrementally loaded into the column, the ream was packed into the column with one rod at a time to ensure a consistent melt during the test. After loading the material sample, a melting time of 2 minutes preceded each test to allow the material sample to fully melt at the test temperature. The capillary rheometer took data points automatically and determined the apparent viscosity (in Pascal »second) at 7 apparent cutoff rates (in second" 1): 50, 100, 200, 500, 1,000, 2,000, and 5,000. the resulting curve was important for the curve to be relatively smooth.If there were significant deviations from a general curve from one point to another, possibly due to the air in the column, the test run was repeated to confirm the results.

The rheology curve resulting from the apparent cutoff rate against the 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 cut-off rate of at least 1,000 seconds "1 are of specific interest because these are the typical conditions found in commercial fiber spinning extruders.

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

The gel permeation chromatography was placed with two analytical columns of 7.5 x 300 millimeters of 5 linear K-microns mixed with PL gel in series. The column and detector temperatures were 30 ° C. The mobile phase was tetrahydrofuran (THF) of high performance liquid chromatography (HPLC) class. The pumping rate was 0.8 milliliters per minute with an injection volume of 25 microliters. The total run time was 30 minutes. It is important to note that the new analytical columns should be installed every four months, a new guard column around each month, and a new online filter around each month.

Polystyrene polymer standards, obtained from Aldrich Chemical Company, were mixed in a solvent of dichloromethane (DCM): THF (10:90) both of high performance liquid chromatography class, to obtain concentrations of 1 milligram / mL. Multiple polystyrene standards can be combined in a normal solution as long as their maximums do not overlap when they are chromatographed. A range of standards of around 687 to 400,000 molecular weight were prepared. Examples of standard blends with Aldrich polystyrenes of variable weight average molecular weights included: 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).

Then the supply verification standard was prepared. First 10 grams of a 200,000 molecular weight poly (lactic acid) standard, Catalog # 19245 obtained from Polysciences Inc., was dissolved in 100 ml of HPLC-class DCM in a glass jar with a lined lid using an orbital shaker ( at least 30 minutes). After the mixture was poured onto a dry and clean glass plate, the solvent was allowed to evaporate, then placed in a vacuum oven preheated to 35 ° C and dried for about 14 hours under a vacuum of 25 millimeters of vacuum. mercury. Then, 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 grid) taking care not to add too much sample and to cause the grinder to freeze. A few grams of the milled sample were stored in a dry glass bottle in a desiccator, while the rest of the sample can be stored in a freezer in a similar type vial.

It was important to prepare a new verification standard before the start of each new sequence, and due -fel, & & Because the molecular weight is very affected by the sample concentration, great care must be taken in its weighing and in the preparation. To prepare the verification standard, the reference standard of poly (lactic acid) of 0.0800g ± 0.0025g of 200,000 weight average molecular weight was weighed in a scintillation vessel. Then, using a dedicated repipet or a volumetric pipette, 2 ml of DCM was added to the container and the cap screwed tightly. The sample was allowed to dissolve completely. The sample was oscillated in an orbital shaker, such as a Thermoline Roto Mix (type 51300) or a similar mixer, if necessary. To evaluate if it was dissolved, the container was exposed to an angle of 45 °. The container was slowly turned and the liquid was seen as it floated down on the glass. If the bottom of the container did not appear smooth, the sample was not completely dissolved. It may take several hours for the sample to dissolve. Once dissolved, 18 ml of THF was added using a volumetric pipette or a dedicated repipet, the container was tightly capped and mixed.

The sample preparations started by weighing 0.0800g ± 0.0025g of the sample in a dry and clean scintillation vessel (great care must be taken in weighing and in preparation). Two ml of DCM was added to the vessel with a volumetric pipette or a dedicated repipet and the cap screwed tightly. The sample was allowed to dissolve bá * faÍ.AA * »- * d» ~ -? - - - * .a¿ ..k i .1 completely using the same technique described in the standard verification preparation mentioned above. After 18 ml of THF was added using a volumetric pipette or a dedicated repipet, the container was tightly capped and mixed.

The evaluation was started by performing a test injection of a standard preparation to test the equilibration of the system. Once the equilibration was made, the standard preparations were injected. After they were run, the standard verification preparation and then the sample preparations were injected first. The standard verification preparation was injected every seven sample injections and at the end of the test. Care must be taken not to take more than two injections of any container and those two injections must be made within 4.5 hours of each other.

There are four parameters of quality control to evaluate the results. First, the correlation coefficient of the fourth order regression calculated for each standard should not be less than 0.950 and not more than 1.050. Second, the relative standard deviation of all weight average molecular weights of the standard verification preparations should not be more than 5.0%. Third, the average weight average molecular weights of standard preparation preparation injections should be t ^ -hS *. < »» AÍ »^ | . -, *** -l ^ .. -. . .i *, * .. Í ..? .? ** _ *,. "J ^^. * _ * ^ _ _ ^ "_ 1, it * LA within 10% of the weight average molecular weight over the first standard preparation preparation check. Finally, the response of lactide for the standard injection of 200 micrograms per milliliter (μg / mL) should be recorded on an SQC data scheme. Using the outline control lines, the response must be within the defined SQC parameters.

Calculate the molecular statistics based on the calibration curve generated from the standard polystyrene preparations and the constants for poly (lactic acid) and polystyrene in THF at 30 ° C. These are: polystyrene (K = 14.1 * 105, alpha = 0.700) and poly (lactic acid) (K = 54.9 * 105, alpha = 0.639).

Shrinkage of Heat Fibers The equipment required for the determination of heat shrinkage includes: a convection oven (Thelco model 160DM laboratory oven available from Precision and Scientific Inc., of Chicago Illinois), sinking weight of 0.5 g (+/- 0.06g), one-inch binder fasteners, masking tape, graph paper with at least one-inch squares, foam board (11 x 14 inches) or an equivalent substrate to hold the graph paper and the samples. He s.iA-? jaA.anil.i.n. ?. ^. JL ..... ¿Ai-. . " ? .ii **? ^ *. ^ .. . . , - - -óó *, _ * - r "^? * a-?? .J A The convection oven must be capable of a temperature of around 100 ° C.

The fiber samples are spun with melt at their respective spinning conditions. In general, a bundle of 30 filaments is preferred and mechanically pulled to obtain fibers with a jet and stretch ratio of 224 or better. Only the fibers of the same jet and stretch ratio can be compared to one another in relation to their heat shrinkage. The ratio of jet and stretch of a fiber is the ratio of the speed of the pull roller down divided by the linear extrusion rate (distance / time) of the melt polymer leaving the spinning organ. The spinning fiber is usually collected on a reel using a reel. The collected fiber bundle was separated into 30 filaments, if a bundle of 30 filaments was not already obtained, and cut into 9-inch lengths.

The graph paper was taped onto the poster board where one edge of the graph paper was married to the edge of the poster board. One end of the fiber bundle was taped, no more than an inch in end. The taped end was attached to the poster board at the edge where the graph paper was married so that the edge of the bra rests on one of the horizontal lines on the ij-L.M.Jtj * -Vitt iti • 'graph paper while holding the bundle of fibers in place (the taped end should be very inconspicuous as it is secured under the fastener). The other end of the bundle was pulled tight and aligned parallel to the vertical lines on the graph paper. Then, 7 inches below the point where the fastener is attaching the fiber, the 0.05 gram sinker was punctured around the bundle of fiber. The clamping process was repeated for each duplicate. Usually 3 duplicates can be held at the same time. The marks must be made on the graph paper to indicate the initial positions of the sinks. The samples were placed in the oven at a temperature of around 100 ° C so that the samples hung vertically and did not touch the poster board. At time intervals of 5, 10 and 15 minutes the new location of the sinkers was quickly marked on the graph paper and the samples were returned to the furnace.

After the test was completed, the cardboard of the poster was removed and the distances between the origin (where the fastener retained the fibers) and the marks at 5, 10 and 15 minutes were measured with a ruler graduated to 1/16 of inch. 3 duplicates per sample are recommended. Calculate averages, standard deviations and percent shrinkage. The percent shrinkage is calculated as (initial length / measured length) divided by the initial length and multiplied by 100. As reported in the examples given herein and as used in the claims, the heat shrink value represents the amount of heat shrinkage exhibited by a fiber sample at a temperature of about 100 ° C. for a period of time of about 15 minutes as determined according to the preceding test method.

Contact Angle The equipment includes the DCA-322 Dynamic Contact Angle Analyzer and a WinDCA program (version 1.02), both available from ATI-CAHN Instruments, Inc., of Madison Wisconsin. The test was performed on the "A" circuit with a balance agitation attached. The calibrations must be done monthly on the motor and daily on the scale (100 mg of mass used) as indicated in the manual.

The thermoplastic compositions were spun into fibers and the free fall sample (jet and zero stretch) was used for the determination of the contact angle. Care should be taken through fiber preparation to minimize fiber exposure to handling to ensure that contamination is kept to a minimum. The fiber sample was attached to the wire hanger with scotch tape so that 2-3 centimeters of fiber were spread beyond the end of the wire. í ?? k .t. * .- * ..., ... l¿ * t *? -. _. ... * ¿_ -? a * * - * x ^ l * Jí hanger. Then the fiber sample was cut with a razor so that approximately 1.5 centimeters extended beyond the end of the hanger. An optical microscope was used to determine the average diameter (3 to 4 measurements) along the fiber.

The sample on the wire hanger was suspended from the balance agitation on circuit A. The immersion liquid was distilled water and this was changed for each sample. The sample parameters were entered (for example, fiber diameter) and the test was started. The phase advanced to 151.75 micras / second until it detected the depth of zero immersion when the fiber made contact with the surface of distilled water. From the zero depth of immersion, the fiber advanced into the water by 1 centimeter, remained for zero seconds and then immediately retreated 1 centimeter. The autoanalysis of the contact angle carried out by means of the program determined the advance and return contact angles of the fiber sample based on standard calculations identified in the manual. The contact angles of zero or of < 0 indicate that the sample had been completely wetted. Five duplicates were tested for each sample and one statistical analysis was calculated for the mean standard deviation, and the coefficient of percent variation. As reported in the examples given herein and as used by the claims, the advance contact angle value represents the advancing contact angle of the distilled water on a fiber sample determined according to the preceding test method. Similarly, as reported in the examples given herein and as used in the claims, the back contact angle value represents the back contact angle of the distilled water on a fiber sample determined according to the test method. precedent Evaluation of Return Flow and Fluid Absorption (FIFE) The Return Flow and Fluid Absorption Evaluation (FIFE) test was used to determine the absorbency time and return flow of a personal care product. A Digi-Staltic Master-Flex automatic assortment system was supplied with colored salt water with a small amount of blue FD &C stain to provide 80 mL of insults and was filled several times to eliminate any air bubbles. The product samples, the diapers for the care of the infant, were prepared without elastic so that they could easily lie flat. The samples of blotting paper of 3.5 inches by 12 inches were weighed. These papers were placed on the cardboard of evaluation of absorption of fluid and flow back, a simple cardboard with a raised platform of 3 inches x 6 inches in half. The blotting papers were aligned so that they & ? ** t? »Aitzí. . *, .L. .. < - »ft" - ** .. M ^ t. Í * ¡* -? ..,. -,. *. -, _ _. TJ? - ti run in a longitudinal direction along either side of the elevated platform The paper was then aligned so that the area to be insulted was carefully centered on a raised platform, with the top sheet facing upwards so that the wrinkles on the nonwoven top sheet were not visible. The second carton for evaluation of fluid absorption and return flow was then placed on top of the product.This apparatus consists of a flat cardboard that was intersected by a hollow cylinder protruding only from the upper side of the cardboard. where the cylinder intersected the plain plane of the cardboard was hollow.The inner diameter of the cylinder was 5.1 centimeters.A funnel with an internal diameter of 7 millimeters at the short end was placed in the cylinder.The fluid was then filled by the pump directly to the The absorption time was recorded by means of a chronometer from the time the fluid stuck in the funnel until there was no visible fluid on the surface of the sample. The blotting papers were checked for product runoff and if any occurred, the weight of the blotting papers would have been measured to determine the amount of fluid that dripped. In the test described, no runoff occurred. Approximately one minute passed before the second discharge was applied in the same way. Again, a third discharge was applied and it was clocked in the same way. If desired, you can then follow a lA-A i ** .. * procedure to determine the amount of fluid that flows back when the product is under pressure. In this case, only absorption rates were recorded.

Loss of Transepidermal Water (TEWL) The Transepidermal Water Loss arm (TEWL) arm band test was used to measure changes in skin hydration as a result of product use. A lower evaporation value, as measured by means of a Servo Med Evaporimeter, is indicated for a product that promotes skin dryness. This test actually reports a difference in evaporation values. A measurement of the moisture evaporation rate is taken before the test and then immediately afterwards. The difference in these numbers provides the transepidermal water loss value as reported in the results. A lower transepidermal water loss value implies that a product provides a better ability to breathe into the skin.

The product, in this case the diapers for the care of the infant, was prepared by hand without any elastics or ears. The basic structure of the diaper was the same, but one control diaper consisted entirely of standard materials and the other had all standard materials except the top sheet, which was composed of biodegradable nonwoven. The target area for the downloads was drawn with a permanent marker on the outside of the product. The entire test occurred in a controlled environment of 72 + 4 ° F with a relative humidity of 40 + 5%. The subjects were adult women who were carefully selected to ensure that they did not have conditions that could potentially alter the results of such a test.

The subjects were relaxed in a controlled environment until a stable baseline reading of less than 10 g2 / m / hour was obtained with the Servo Med Evaporimeter. These measurements were carried out on the subjects' inner forearm. The Masterflex Digi-Staltic loading / dispensing pump was used with silicone tubes in the pump head, which was connected to a neoprene pipe for the assortment, using barbed fittings. The end of the neoprene jet tube was placed on the forearm of a subject and the product was applied to the forearm with the target discharge area directly on top of the tube opening. The product is secured with tape that was wrapped around the diaper and did not make contact with the skin. The diaper was then loaded with three discharges of 60 mL of salt water at 45 second intervals and the tube was removed. The product was also secured with a stretchable net and the subject was asked to sit for an hour. After 60 minutes of use, the product was removed and the evaporimeter was then used to obtain the readings every JidAi -.'- t. tt? -? second for 2 minutes in the same area on the forearm where the baseline readings were taken. The reported result is the difference between one hour readings and the baseline.

Examples Example 1 The fibers were prepared using varying amounts of a poly (lactic acid), a polypropylene and a compatibilizer. The poly (lactic acid) polymer (PLA) was obtained from Chronopol Inc., of Golden Colorado, and had a L: D ratio of 100 to 0, a melt temperature of about 175 ° C, an average molecular weight of weight of about 181,000, a number average molecular weight of about 115,000, a polydispersity index of about 1.57, and a residual lactic acid monomer value of about 2.3 percent by weight. The polypropylene polymer (PP) was obtained from Himont Incorporated under the designation Polypropylene Polymer PF305, which had a specific gravity of between about 0.88 to about 0.92 and a melt temperature of about 160 ° C. The compatibilizer was obtained from Baker-Petrolite Corporation of Tulsa, Oklahoma, under the designation ethoxylated alcohol UNITHOX® 480, which had a melting temperature of about 160 ° C and an average number-average molecular weight of about 2,250.

To prepare a specific thermoplastic composition, the various components were first mixed with drying and then mixed with melt in a counter-rotating twin screw to provide vigorous mixing of the components. Mixing with melt involved a partial or complete melting of the components combined with the cutting effect of the rotating mixing screws. Such conditions are conducive to optimal mixing and dispersion of the components of the thermoplastic composition. Twin screw extruders such as Haake Rheocord 90, available from Haake GmbH of Karlsautte, Germany, or a twin screw mixer Brabender (catalog No. 05-96-000) available from Brabender Instruments of South Hackensack, New Jersey, or others Comparable twin screw extruders are very suitable for this task. The molten composition is cooled after extrusion of the melt mixer onto either a surface or roll cooled with liquid and / or by means of forced air passed over the extrudate. The cooled composition is then pelletized subsequently for conversion to fibers.

The conversion of these resins into fibers and non-wovens was carried out on a 0.75-inch diameter domestic extruder with an L: D ratio screw. ji í.ií.ítAiÁ-? tAlá ***!., **. *. , ^ ¿- - r * 1 ~ * ^.,. **. . . . ....... ^ ._, ....... .... -., ^ .. ^ J? T (length: diameter) of 24: 1 and three heating zones which they fed in of a transfer pipe from the extruder to the spin pack, which constitutes the fourth heating zone and contains a static mixing unit of the Koch® SMX type of about 0.62 inches in diameter (about 1.6 centimeters), available from Koch Engineering Company, Inc. of New York, New York and then inside of a spinning head (fifth heating zone) and through a spinning plate which is simply a plate with numerous small holes through which the molten polymer will be extruded The spinning plate used here had 15 to 30 holes where each hole had a diameter of about 500 microns. The temperature of each heating zone is indicated sequentially under the heading of extrusion temperatures in Table 2. The fibers are cooled by air using air at a temperature range of 13 ° C to 22 ° C, and are pulled down by a mechanical pull roller is passed to any one winding unit for harvesting, or to a fiber pulling unit for bonding and bonding with spinning, or through an accessory equipment for settling by heat or other treatment prior to harvest.

The fibers were evaluated for contact angle and hysteresis. The angle of advance is a measure of how a material will interact with the fluid dg its first contact with the liquid. The recoil angle is an indication of how the material will behave dg multiple discharges with liquid or in a wet, high humidity environment. The hysteresis is defined, the difference between the contact angles of forward and backward of a material. A low hysteresis, in general, will provide a faster rate of wetting. The composition of the various fibers and the results and evaluations are shown in Table 1.

TABLE 1 Contact Angle Results Composition of Fiber Angle of Contact Angle of Contact Histology (% by weight) of Advance of Recoil (polylactide, polypropylene, Unithox) 100: 0: 0 * 85.3 ° 40.7 ° 44.6 0: 100: 0 * 128.1 ° 93.9 ° 34.2 0: 95: 5 * 120.6 ° 79 ° 41.6 0: 95: 5 * 12 .0 ° 58.5 ° 65.5 95: 05: 5 * 89.2 ° 10.0 ° 79.2 70: 30: 0 * 92.37 ° 56.5 ° 35.8 55: 37: 8 111.7 ° 51.4 ° 60.3 6: 27: 9 117.4 ° 40.1 ° 77.3 48:39:13 106.3 ° 0 ° 106.3 52:35:13 97.6 ° 16.8 ° 80.8 61:26:13 88.6 ° 5.8 ° 82.8 70.17: 13 86.7 ° 0 ° 86.7 51:34:15 92.8 ° 3.3 ° 89.5 76.5: 8.5: 15 86.1 ° 0 ° 86.1 * Not an example of the present invention.

It should be noted that the mixtures listed here have very high hysteresis values, in the range of 60-110 degrees. In general, it is expected that a high hysteresis value will inhibit wetting rates. However, the unexpected result obtained was that these high hysteresis fibers showed very high wetting rates as demonstrated by the non-woven test results.

Example 2 A sample of nonwoven material of the present invention was prepared. The sample comprised 61% by weight of polylactide, 96% by weight of polypropylene and 13% of UNITHOX® 480.

This mixture was compared with a current diaper lining control in the test for the time of absorption of fluid for multiple discharges, for the dryness of the skin and for the biodegradation of the material.

The Return Flow and Fluid Absorption Evaluation (FIFE) is used to determine the absorption time of consecutive discharges in a product for infant care. Transepidermal Water Loss (TEWL) uses an evaporimeter to determine the fluid evaporation rate of this skin. A lower evaporation rate means drier skin. This test calculates a difference between a baseline evaporation rate and the rate of evaporation after teÁitiiti A? I i-xi * í -. * l. i use a product that has suffered a discharge with salt water on the forearm.

The biodegradability test was carried out by Organic Waste Systems, Ine, according to the ASTM-5338.92 standard modified so that the test was carried out isothermally at 58 ° C.

The nonwovens demonstrated improved fluid handling properties over the polypropylene treated with current surfactant as evidenced by the following results in Table 2.

TABLE 2 Non-Woven Test Results Even though a polypropylene sample was not run for the biodegradability experiment, it is well known that polypropylene does not undergo any significant degradation. The polylactide in the polylactide / polypropylene / Unithox (PPU) mixture, however, will be degraded and the samples showed a degradation of 50.3 percent after only 45 days. It is feasible that after an extended period of time all the PLA will be degraded.

The shorter absorption time demonstrated by polylactide / polypropylene / Unithox is essential to achieve dryness in a personal care product. This low absorption time indicates that fluid discharges are more quickly pulled into the product. It is important to note that while the absorption time increases with consecutive discharges, it remains significantly better than the polypropylene control and the absorption time is currently increased at a slower rate than for the control. The control is a polypropylene treated with surfactant, where the surfactant has a tendency to wash off during consecutive discharges. Polylactide / polypropylene / Unithox has the additional advantage that it is inherently wettable and this wetting is more permanent. These faster absorption times are somewhat of a surprise in light of the fact that the materials have such high hysteresis values. This is a unique and unexpected result to achieve such rapid absorption rates at high hysteresis values.

The results of transepidermal water loss give an indication of how dry the skin will keep the product, in this case, a diaper for the care of the baby who is using it. For this particular test, a lower transepidermal water loss value is desired. This test used a current diaper control and a diaper that was constructed with a polylactide / polypropylene / Unithox liner. As the results indicate, the polylactide / polypropylene / Unithox liner gave an average transpidermal water loss reading of more than 20% lower than that of the current diaper liner. This is a significant improvement in fluid handling over the current polyolefin system.

In summary, the non-woven polylactide / polypropylene / Unithox material had a higher degree of biodegradability than the existing polyolefin systems. This improved biodegradability can address some of the environmental concerns associated with current personal care products. This biodegradability does not come with sacrificing performance as demonstrated by the improved fluid handling properties. With a 28% reduction in the value of transepidermal water loss and with much faster absorption rates, the system of iilxiU. ?? £ 3bJHM ^ *. L ?. ***** * *** t *? l ^ t * &MÉát¡ßtf & amp; A & i. * ¿, -. *. . **?. **. «-. . ** *. *. ? U. í? »Polylactide / Polypropylene / Unithox will promote dry skin when implemented in a personal care product.

Those skilled in the art will recognize that the present invention is capable of many modifications and variations without departing from the scope thereof. Therefore, the detailed description and examples set forth above are intended to be illustrative only and are not intended to limit, in any way, the scope of the invention, as set forth in the appended claims.

Claims

R E I V I N D I C A C I O N S

1. A biodegradable nonwoven material comprising a plurality of fibers of a thermoplastic composition, wherein the thermoplastic composition comprises: to. an aliphatic polyester polymer in an amount by weight that is between about 45 to about 90% by weight, wherein the aliphatic polyester polymer forms an essentially continuous phase; b. polyolefin microfibers in an amount by weight that is from more than 0 to about 45 percent by weight, wherein the polyolefin microfibers have a diameter that is less than about 50 microns and the polyolefin microfibers form a phase discontinuous essentially enclosed within the essentially continuous phase of aliphatic polyester polymer; Y c. a compatibilizer, which exhibits a hydrophilic-lipophilic balance ratio that is between about 10 to about 40, in an amount by weight that is between about 7 to about 25 percent by weight, wherein all the per hundred by weight are based on the total weight amount of the aliphatic polyester polymer; the I l * polyolefin microfibers and the compatibilizer present in the thermoplastic composition.

2. The biodegradable nonwoven material as claimed in clause 1, characterized in that 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 biodegradable nonwoven material as claimed in clause 2, characterized in that the aliphatic polyester polymer is poly (lactic acid).

4. The non-woven biodegradable material as claimed in clause 1, characterized in that 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.

5. The non-woven biodegradable material as claimed in clause 4, characterized in that the polyolefin is selected from the group consisting of polyethylene and polypropylene.

6. The non-woven biodegradable material as claimed in clause 1, characterized in that the polyolefin microfibers have a diameter that is less than about 25 micrometers.

7. The biodegradable nonwoven material as claimed in clause 1, characterized in that the polyolefin microfibers are present in an amount by weight that is between about 5 to about 40 weight percent.

8. The non-woven biodegradable material as claimed in clause 1, characterized in that the compatibilizer is an ethoxylated alcohol.

9. The non-woven biodegradable material, as claimed in clause 1, characterized in that the thermoplastic composition exhibits a Reverse Contact Angle value that is beneficially less than about 55 degrees.

10. The biodegradable nonwoven material as claimed in clause 1, characterized in that 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 polyolefin microfibers are present in an amount by weight that is between about 5 to about 40 percent by weight; the compatibilizer is an ethoxylated alcohol; and the thermoplastic composition exhibits a Backward Contact Angle value that is less than about 55 degrees.s.

11. The non-woven biodegradable material as claimed in clause 10, characterized in that the aliphatic polyester polymer is poly (lactic acid) and the polyolefin is selected from the group consisting of polyethylene and polypropylene.

12. A non-woven biodegradable material comprising a plurality of multi-component fibers, wherein the multi-component fibers are prepared from a -t ¡k - * "** - ••• * - • -" * - "- - * - -. * .-. thermoplastic composition, wherein the thermoplastic composition comprises: to. an aliphatic polyester polymer in an amount by weight that is between about 45 to about 90% by weight, wherein the aliphatic polyester polymer forms an essentially continuous phase; b. polyolefin microfibers in an amount by weight that is from more than 0 to about 45 percent by weight, wherein the polyolefin microfibers have a diameter that is less than about 50 microns and the polyolefin microfibers form a phase discontinuous essentially enclosed within the essentially continuous phase of aliphatic polyester polymer; Y c. a compatibilizer, which exhibits a hydrophilic-lipophilic balance ratio that is between about 10 to about 40, in an amount by weight that is between about 7 to about 25 percent by weight, wherein all the per hundred by weight 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 fiber of multiple components exhibits a Backward Contact Angle value that is less than about 55 degrees.

13. The biodegradable non-woven material as claimed in clause 12, characterized in that the multi-component fiber exhibits a Heat Shrink value that is less than about 10 percent.

14. The biodegradable nonwoven material as claimed in clause 12, characterized in that 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 biodegradable nonwoven material as claimed in clause 14, characterized in that the aliphatic polyester polymer is poly (lactic acid).

16. The non-woven biodegradable material as claimed in clause 12, characterized in that 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 non-woven biodegradable material as claimed in clause 16, characterized in that the polyolefin is selected from the group consisting of polyethylene and polypropylene.

18. The non-woven biodegradable material as claimed in clause 12, characterized in that the polyolefin microfibers have a diameter that is less than about 25 micrometers.

19. The biodegradable nonwoven material as claimed in clause 12, characterized in that the polyolefin microfibers are present in an amount by weight that is between about 5 to about 40 weight percent.

20. The non-woven biodegradable material as claimed in clause 12, characterized in that the compatibilizer is an ethoxylated alcohol.

21. The non-woven biodegradable material as claimed in clause 12, characterized in that the - * • *** !! .. * Aliphatic polyester polymer is selected from the group consisting of poly (lactic acid), polybutylene succinate, polybutylene succinate-co-adipate, polyhydroxybutyrate-co-valerate, polycaprolactone, terephthalate sulfonated polyethylene, 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 percent by weight; the compatibilizer is an ethoxylated alcohol; and the multi-component fiber exhibits a Heat Shrink value that is less than about 10 percent.

22. The biodegradable nonwoven material as claimed in clause 21, characterized in that the aliphatic polyester polymer is poly (lactic acid) and the polyolefin is selected from the group consisting of polyethylene and polypropylene.

23. A non-woven biodegradable material comprising a plurality of multi-component fibers, wherein the multi-component fibers are prepared from a plurality of components, furthermore wherein one of the components §fff¡- * • *. «& *». it comprises an unreacted thermoplastic mixture comprising: to. an aliphatic polyester polymer in an amount by weight that is between about 45 to about 90% by weight, wherein the aliphatic polyester polymer forms an essentially continuous phase; b. polyolefin microfibers in an amount by weight that is from more than 0 to about 45 percent by weight, wherein the polyolefin microfibers have a diameter that is less than about 50 microns and the polyolefin microfibers form a phase discontinuous essentially enclosed within the essentially continuous phase of aliphatic polyester polymer; Y c. a compatibilizer, which exhibits a hydrophilic-lipophilic balance ratio that is between about 10 to about 40, in an amount by weight that is between about 7 to about 25 percent by weight, wherein all the per hundred by weight 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 multiple component fibers are arranged in such a configuration that the unreacted thermoplastic component is located on a surface of the multi-component fiber.

24. The non-woven biodegradable material as claimed in clause 23, characterized in that the configuration is selected from a sheath-core, segmented pie-shaped, eccentric sheath-core, side-by-side, or multi-component triple lobe.

25. The non-woven biodegradable material as claimed in clause 23, characterized in that the multi-component fiber exhibits a Heat Shrink value that is less than about 10 percent.

26. The biodegradable nonwoven material as claimed in clause 23, characterized in that 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 non-woven biodegradable material as claimed in clause 23, characterized in that the polyolefin is selected from the group consisting of homopolymers and polymers 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 non-woven biodegradable material as claimed in clause 23, characterized in that the polyolefin microfibers have a diameter that is less than about 25 micrometers.

29. The non-woven biodegradable material as claimed in clause 23, characterized in that the polyolefin microfibers are present in an amount by weight that is between about 5 to about 40 weight percent.

30. The biodegradable nonwoven material as claimed in clause 23, characterized in that 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 polyolefin microfibers are present in a weight amount that is between about 5 to about 40 percent by weight; the compatibilizer is an ethoxylated alcohol; and the multi-component fiber exhibits a Heat Shrink value that is less than about 10 percent.

31. A non-woven biodegradable material comprising a plurality of multi-component fibers, characterized in that the multi-component fibers exhibit an angle value of Retracting Contact that is less than less than about 55 degrees.

32. A disposable absorbent product comprising a liquid pervious topsheet, a fluid acquisition layer, an absorbent structure, and a liquid impervious backsheet, wherein at least one of the liquid permeable topsheet of the layer of fluid acquisition or liquid impervious backing sheet comprises a biodegradable nonwoven material comprising a plurality of multi component fibers prepared from a thermoplastic composition, wherein the thermoplastic composition comprises: to. an aliphatic polyester polymer in an amount by weight that is between about 45 to about 90% by weight, wherein the aliphatic polyester polymer forms an essentially continuous phase; b. polyolefin microfibers in an amount by weight that is from more than 0 to about 45 percent by weight, wherein the polyolefin microfibers have a diameter that is less than about 50 microns and the polyolefin microfibers form a phase discontinuous essentially enclosed within the essentially continuous phase of aliphatic polyester polymer; Y c. a compatibilizer, which exhibits a hydrophilic-lipophilic balance ratio that is between about 10 to about 40, in an amount by weight that is between about 7 to about 25 percent by weight, wherein all the per hundred by weight 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 fiber of multiple components exhibits a Backward Contact Angle value that is less than about 55 degrees.

33. The disposable absorbent product, as claimed in clause 32, characterized in that the multi-component fiber exhibits a Heat Shrink value that is less than about 10 percent.

34. The disposable absorbent product, as claimed in clause 32, characterized in that 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.

35. The disposable absorbent product, as claimed in clause 34, characterized in that the aliphatic polyester polymer is poly (lactic acid).

36. The disposable absorbent product as claimed in clause 32, characterized in that 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 as claimed in clause 36, characterized in that the polyolefin is selected from the group consisting of polyethylene and polypropylene.

38. The disposable absorbent product, as claimed in clause 32, characterized in that the polyolefin microfibers have a diameter that is less than about 25 microns.

39. The disposable absorbent product, as claimed in clause 32, characterized in that the polyolefin microfibers are present in an amount by weight that is between about 5 to about 40 percent by weight.

40. The disposable absorbent product, as claimed in clause 32, characterized in that the compatibilizer is an ethoxylated alcohol.

41. The disposable absorbent product, as claimed in clause 32, characterized in that 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 polyolefin microfibers are present in a weight amount that is between about 5 to about 40 percent by weight; the compatibilizer is an ethoxylated alcohol; and the multi-component fiber exhibits a Heat Shrink value that is less than about 10 percent.

42. The disposable absorbent product, as claimed in clause 41, characterized in that 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, as claimed in clause 32, characterized in that the liquid permeable topsheet, the fluid acquisition layer, and the liquid impervious backsheet comprise the biodegradable nonwoven material comprising a plurality i * m? -z *. * of multi-component fibers prepared from the thermoplastic composition.

44. A disposable absorbent product comprising a liquid permeable topsheet, an absorbent structure, and a liquid impervious backsheet, wherein at least one of the liquid permeable topsheet or the liquid impermeable backsheet comprises a material non-woven biodegradable fabric comprising a plurality of multi-component fibers prepared from a thermoplastic composition, wherein the thermoplastic composition comprises: to. an aliphatic polyester polymer in an amount by weight that is between about 45 to about 90% by weight, wherein the aliphatic polyester polymer forms an essentially continuous phase; b. polyolefin microfibers in an amount by weight that is from more than 0 to about 45 percent by weight, wherein the polyolefin microfibers have a diameter that is less than about 50 microns and the polyolefin microfibers form a phase discontinuous essentially enclosed within the essentially continuous phase of aliphatic polyester polymer; Y c. a compatibilizer, which exhibits a hydrophilic-lipophilic balance ratio that is between about 10 to about 40, in an amount by weight that is between about 7 to about 25 percent by weight, wherein all the per hundred by weight 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 fiber of multiple components exhibits a Backward Contact Angle value that is less than about 55 degrees.

45. The disposable absorbent product, as claimed in clause 44, characterized in that the multi-component fiber exhibits a Heat Shrink value that is less than about 10 percent.

46. The disposable absorbent product, as claimed in clause 44, characterized in that 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, as claimed in clause 46, characterized in that the aliphatic polyester polymer is poly (lactic acid).

48. The disposable absorbent product as claimed in clause 44, characterized in that 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 as claimed in clause 48, characterized in that the polyolefin is selected from the group consisting of polyethylene and polypropylene.

50. The disposable absorbent product, as claimed in clause 44, characterized in that the polyolefin microfibers have a diameter that is less than about 25 microns.

51. The disposable absorbent product, as claimed in clause 44, characterized in that the polyolefin microfibers are present in an amount by weight that is between about 5 to about 40 percent by weight.

52. The disposable absorbent product, as claimed in clause 44, characterized in that the compatibilizer is an ethoxylated alcohol.

53. The disposable absorbent product, as claimed in clause 44, characterized in that 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 polyolefin microfibers are present in a weight amount that is between about 5 to about 40 percent by weight; the compatibilizer is an ethoxylated alcohol; and the multi-component fiber exhibits a Heat Shrink value that is less than about 10 percent. • - "• '- > ---» »-" «***

54. The disposable absorbent product, as claimed in clause 53, characterized in that 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 as claimed in clause 44, characterized in that the liquid permeable top sheet and the liquid impermeable backing sheet comprise the biodegradable nonwoven material comprising a plurality of multi component 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 impervious backsheet, the fluid acquisition layer, or the liquid impervious backsheet comprise a non-woven biodegradable material comprising a plurality of multi-component fibers prepared from a thermoplastic composition, wherein the multi-component fiber exhibits a Reverse Contact Angle value that is less than about 55 degrees. SUMMARY A biodegradable, nonwoven material having improved fluid handling properties is disclosed. The biodegradable nonwoven material demonstrates superior contact angle hysteresis, faster absorption times, and improved skin dryness compared to nonwovens of the prior art. In addition, these biodegradable nonwoven materials also exhibit high wetting rates, which is unexpected based on higher hysteresis values. The nonwoven material can be produced using thermoplastic compositions which comprise an unreacted mixture of aliphatic polyester polymer as a continuous phase, polyolefin microfibers as a discontinuous phase enclosed within the continuous phase of aliphatic polyester polymer, and a compatibilizer for the aliphatic polyester polymer and the polyolefin microfibers. The fiber of multiple components exhibits substantial biodegradable properties and a good humidification, but nevertheless, it is easily processed. The biodegradable nonwoven materials can be used in a disposable absorbent product that is intended for the absorption of fluids such as body fluids.