MXPA99006199A - Multicomponent fiber - Google Patents

Abstract

Disclosed is a thermoplastic composition comprising 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 biodegradable properties and good wettability yet is easily processed. The thermoplastic composition is useful in making nonwoven structures that may be used in a disposable absorbent product intended for the absorption of fluids such as body fluids.

Description

MULTI-COMPONENT FIBER Background of the Invention Field of the Invention The present invention relates to a multi-component fiber. The multicomponent fiber comprises an unreacted mixture of an aliphatic polyester polymer with a continuous phase, polyolefin microfibers as a discontinuous fas encased within the continuous phase of aliphatic polyester polymer, and a compatibilizer for the aliphatic polyester polymer and the polyolefin microfibers. Multicomponent fiber exhibits essentially biodegradable properties but is easily processed. The multicomponent fiber is used to make non-woven structures that can be employed in a disposable absorbent product intended for the absorption of fluids such as body fluids.

Description of Related Art Disposable absorbent products currently find widespread use in many applications. For example, in the child and infant 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 including an upper sheet, a lower sheet, and an absorbent structure between the upper sheet and the lower sheet. These products usually include some type of fastening system for adjusting the product on the user.

Disposable absorbent products are typically subjected to one or more insults or discharges of liquid, such as water, urine, menstrual fluids or blood during use. As such, the bottom sheet materials of the outer cover of the disposable absorbent products are typically made of liquid insoluble materials which are impervious to liquid, such as polypropylene films, which exhibit sufficient strength and handling capacity so that The disposable absorbent product retains its integrity during use by a user does not allow the run-off of the liquid that insults the product.

Although current disposable baby diapers and other disposable absorbent products have generally been accepted by the public, these products still need improvements in specific areas. For example, many disposable absorbent products can be difficult to dispose of. For example, attempts to discard with water discharge many disposable absorbent products in a toilet inside a sewer system typically leads to blockage of the toilet or of the pipes connecting the toilet to the sewer system. In particular, the outer covering 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 discarded in this manner. If the outer covering materials become too thin in order to reduce the overall volume of the disposable absorbent product to reduce the possibility of blockage of a toilet or sewer pipe, then the covering material will typically not exhibit sufficient strength to avoid tearing or tearing when the outer covering material is subjected to the stresses of normal use by the user.

In addition, the disposal of solid waste is still an increasing concern in the world. As the waste land continues to be filled, there has been an increased demand for a reduction of sources 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. through different means to the incorporation in solid waste disposal facilities such as filling fields.

As such, there is a need for new materials that can be used in the disposable absorbent products that generally retain their integrity and strength during use, but that after such use, the materials can be efficiently discarded. 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 sewer system where the disposable absorbent product is capable of being degraded.

Even though degradable monocomponent fibers are known, problems have been encountered with their use. in particular, the known degradable fibers typically have good thermal dimensional stability so that the fibers usually suffer severe lime shrinkage due to chain relaxation of the polymer during downward heat treatment processes such as thermal lamination bonding.

In contrast, polyolefin materials, such as polypropylene, typically exhibit good thermal dimensional stability but also have problems associated with their use. In particular, the polyolefin fibers typically are 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, permanence or fugitivity and toxicity. In addition, polyolefin fibers are generally non-biodegradable compostable.

It would therefore be desirable to prepare a fiber which exhibits the thermal dimensional stability of polyolefin materials but which is essentially biodegradable and which is wettable without the use of surfactants. A simple solution to this desire would be to simply mix a polyolefin material with a degradable material such as to gain the benefits of using both materials. However, the multi-component fiber components 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 mechanical properties and of processing. It has therefore been proven that it is a challenge for those skilled in the art to combine the components that fulfill these basic processing needs as well as to satisfy the desire that the multicomponent fiber complet be effectively essentially degradable and hydrophilic.

It is therefore an object of the present invention to provide a multicomponent fiber which is essentially degradable in the environment.

It is also an object of the present invention to provide an essentially degradable multicomponent fiber which has a good thermal dimension stability and is hydrophilic without the substantial use of surfactants It is also an object of the present invention to provide an essentially degradable multicomponent fiber which is easily and efficiently prepared and which is suitable for use in the preparation of n-woven structures.

Synthesis of the Invention The present invention relates to an oplastic composition which is essentially biodegradable and which is still easily prepared and easily processed in the desired final structures, such as non-woven structures or fibers.

One aspect of the present invention relates to 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 such as an essentially continuous phase, polyolefin microfiber as an essentially discontinuous phase tucked into 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 multicomponent fiber which is essentially degradable and which is also easily prepared and easily processable in the desired end structures, such as fiber or non-woven structures.

One aspect of the present invention relates to a multicomponent fiber comprising an n-reacted mixture of an aliphatic polyester polymer as an essentially continuous fas, polyolefin microfibers as an essentially discontinuous fas within the continuous phase essentially of aliphatic polyester polymer , and compatibilizer for the aliphatic polyester polymer and the polyolefin microfibers.

In another aspect, the present invention relates to a non-woven structure comprising the multicomponent fiber d described therein.

An incorporation of such a non-woven structure and a lower sheet useful in the disposable absorbent product.

In another aspect, the present invention relates to a disposable absorbent product comprising the multicomponent fiber d described therein.

In another aspect, the present invention relates to a process for preparing the multicomponent fiber described herein.

Detailed Description of Preferred Additions The present invention is directed to 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 condition when cooled to ambient temperature.

It has been found that, by using a non-reacted mixture of an aliphatic polyester polymer as an essentially continuous base, the polyolefin microfibers fuse a discontinuous phase essentially enclosed within the substantially continuous fas of aliphatic polyester polymer, and a compatibilizer for the Aliphatic polyester polymer and polyolefin microfibers, a thermoplastic composition can be prepared wherein such a thermoplastic composition is essentially degradable however its thermoplastic composition is easily processable into fibers and non-woven structures which exhibit effective fibrous mechanical properties and liquid handling properties.

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

In an embodiment of the present invention, it is desired that the aliphatic polyester polymer used be poly (lactic acid). The poly (lactic acid) polymer is generally prepared by the polymerization of lactic acid. However, it will be recognized by a person 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 to represent 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 levogyratory d-enantiomer (hereinafter referred to as "L") and dextrorotatory enantiomer (hereinafter referred to as "D"). "). As a result, by polymerizing a particular enantiomer or by using a mixture of two enantiomers, it is possible to prepare different polymers that are chemically similar but 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 melting temperature, the melting rheology and the crystallinity of the polymer. By being able to control such properties, it is possible to prepare a multi-component fiber exhibiting a desired melt strength, mechanical properties, smoothness and processability properties such as to make attenuated, curled heat-set 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 50 percent by weight about 88 percent by weight, and more suitably from about 55 percent by weight to about 70 percent by weight, where all percent by weight is based on the amount of weight total of the aliphatic polyester polymer, the polyolefin microfiber, and the compatibilizer present in the thermoplastic composition. The compositional ratio of the three components in the thermoplastic composition is generally important for maintaining 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 component proportions can be determined based on the densities of the components. The density of a component is converted to a volume (presuming 100 grams of each component), the volumes of the components are aggregated together for a volume of total thermoplastic composition and the average weight of the components were 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 desirable melt strength, fiber strength, and fiber spinning properties. 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 which has been 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 entangled sufficiently which may result in a thermoplastic composition comprising the aliphatic polyester polymer exhibiting a resistance to relatively weak melting making high-speed processing very difficult. Thus, suitable aliphatic polyester polymers 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 of between about 50,000 to about 400,000 and suitably of about 100,000 to around 300,000. The weight average molecular weight for the polymers or polymer blends can be determined using a method as disclosed in the test methods section given herein.

It is also desired that the aliphatic polyester polymer exhibit a polydispersity index value that is effective for the thermoplastic composition to exhibit desirable melt strength, fiber 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 average molecular weight of the polymer number. 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 the polymer segments comprising Low molecular weight polymers that have lower melt strength properties during spinning. So, it is desired that the aliphatic polyether polymer exhibit a polydispersity index value that is beneficially from about 1 to about 15, m beneficially from about 1 to about 4, suitably from about 1 to about 3. The average molecular weight for polymer polymers or mixtures 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 thermoplastic composition comprising the aliphatic polyester polymer, either in the form of a fiber or in the form of a non-woven structure, will be essentially degradable when disposed of in the environment and exposed to air and / or water. As used here, "biodegradable" is meant to represent that material that is degraded by the action of naturally occurring microorganisms such as bacteria, fungi, and algae.

In the present invention, it is also desired that the aliphatic polyester polymer be compostable. As a result of this, the thermoplastic composition comprising the aliphatic polyester polymer, either in the form of a fibr or in the form of a nonwoven structure, will be essentially compostable when disposed in the environment and exposed to air and / or to water. As used herein, "compostable" is intended to mean that a material is capable of undergoing biological decomposition at a composting site such that material n is visually distinguishable and is broken into carbon dioxide water, inorganic compounds and biomass, a rate consistent with known compostable materials.

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

The 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 9 degrees. In contrast, as used herein, the term "hydrophilic" refers to a material having an angle of contact at an angle of less than 90. For the purposes of this application, contact angle measurements can be determined as established by Robert J. Good and Robert J. Stromberg, editors of the work "Experimental Methods of Science of Colloid Surface", volume II (Plenum Press, 1979), pages 63-70.

It is generally desired that both the aliphatic polyester polymer and the polyolefin be processable co-melted. It is therefore desired that the aliphatic polyester polymer and the polyolefin exhibit a melt flow rate that is beneficially between about 1 gram per 10 minutes to about 200 grams per 10 minutes, suitably about 10 grams per. 10 minutes to about 100 grams per 10 minutes, and more suitably from about 20 grams per 10 minutes to about 40 grams per 10 minutes. The melt flow rate of a material can be determined according to the test method ASTM D1238-E incorporated in its entirety here 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 micrometer and more adequately less than about 1 micrometer.

In one embodiment of the present invention, polyolefin microfiber comprises a percentage of the cross-sectional area of a multicomponent fiber prepared to the thermoplastic composition of the present invention that effective for the multicomponent fiber to exhibit desirable melt strength., fiber mechanical strength and fiber spinning properties. In general, if polyolefin microfiber comprises a percentage of the cross-sectional area of a multicomponent fiber that is m high, this generally results in a multi-compound fiber that will not be essentially biodegradable or difficult to process. 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 multicomponent fiber that will not exhibit effective structural properties or that may be difficult to process. Thus, the polyolefin microfiber desirably comprises a percentage of the cross-sectional area of a multicomponent fiber that is beneficially less than about 20 percent of the cross-sectional area of the multicomponent fiber, more benignly less than about 5 percent. percent of the cross-sectional area of the multi-component fiber and suitably less than about 10 percent of the cross-sectional area of the multicomponent fiber.

As used herein, the term "fiber" or "fibrous" is intended to refer to a material wherein the length-to-diameter ratio of such material is greater than about 10. Conversely, a "non-fibrous" or "non-fiber" material "is meant to refer to a material where the ratio of length to diameter of such material is about 10 or less.

The polyolefin is generally desired for what is 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 substantial thermal dimensional shrinkage of the thermoplastic composition during processing as long as they remain generally 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. Polyolefin microfibers will be present in the thermoplastic composition in an amount by weight that is beneficially between more than percent by weight to about 45 percent by weight. suitably from about 5 percent by weight about 40 percent by weight, and more suitably from about 10 percent by weight to about 30 percent by weight, where all percentages by weight are based on the Total amount of weight of the aliphatic polyester polymer of the polyolefin microfiber and of the compatibilized present in the thermoplastic composition. It is generally important that the polyolefin be in 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 fabrics, without affecting negatively the biodegradability of aliphatic polyester or the substantial biodegradability of the thermoplastic composition or of the materials formed of 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 of the present invention, and the fibers prepared from the thermoplastic composition, are generally hydrophilic so that such fibers are used in the disposable absorbent products which are insulted with aqueous liquids such as water, urine menstrual fluids or blood. Therefore, it has been found desirable to use another component as a surfactant in the thermoplastic composition of the present invention in order to achieve the desired hydrophilic properties.

Furthermore, it has been found desirable to improve the processability of the aliphatic polyester polymer and the polyolefin microfibers, since such polymers are not chemically identical and are therefore somewhat incompatible with one another 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 themselves. Generally, 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 the polyolefin microfibers in a single thermoplastic composition.

Therefore, the third component of the thermoplastic composition is a compatibilizer for the aliphatic polyester polymer and the polyolefin microfibers. Suitable compatibilizers for use in the present invention generally comprise a hydrophilic section which will generally be compatible with the aliphatic polyester polymer and the hydrophobic section thereof. which is generally compatible with polyolefin microfibers. These hydrophilic and hydrophobic sections generally exist in separate blocks so that the overall compatibilizing structure can be di-block or random block. It is generally desired that the compatibilizer initially function 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, such as a fiber or non-woven structure, 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 combinations thereof. Examples of suitable compatibilizers include the ethoxylated alcohols UNITHOX® 480 and U ITHOX®750 or the Acid 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 a desirable melt strength, fiber strength, and fiber spinning properties. In general, if the weight average molecular weight of a compatibilizer is very high, the compatibilizer will not mix well with the other components in the thermoplastic composition because the viscosity of the compatibilizer will be very high so that it lacks the necessary mobility to mix. 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 exhibit average molecular weight weights that are beneficially from about 1,000 to about 100,000, suitably from about 1,000 to about 50,000, and more suitably from about 1,000. to around 10,000. The weight average molecular weight for the 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 ratio). The hydrophilic-lipophilic balance ratio of a material describes the relative proportion of the hydrophilicity of the material. The balance and hydrophilic-lipophilic ratio was calculated as the weight average molecular weight of the hydrophilic part divided by the average molecular weight of the total weight of the material, the value of which is then multiplied by 20. If the value of hydrophilic balance ratio- Lipophilic is very low, the material will not generally provide the desired improvement in hydrophilicity. Conversely, if the hydrophilic-lipophilic balance ratio value is very high, material will generally not be mixed in the thermoplastic composition due to chemical incompatibility and differences in viscosities with the other components. Thus, the compatibilizers useful in the present invention exhibit hydrophilic-lipophilic balance ratio values that are beneficially from about 10 to about 4 suitably from about 10 to about 20, and suitably from about 12 to about around 18 It is generally desired that the compatibilizer is 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 compatibilizer will be necessary to achieve effective mixing with the other components in thermoplastic composition. In general, too much compatibilizer will lead to problems of thermoplastic composition processing. The compatibilizer will be present in the thermoplastic composition in a weight amount that is beneficially between about 7 percent by weight about 25 percent by weight, most beneficially from about 10 percent by weight to about 25 percent by weight. by weight, suitably from about 12 percent p weight to about 20 percent by weight, and more suitably from about 13 percent by weight to about 1 percent by weight, where all percent by weight They 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 of the present invention have been described above, such a thermoplastic composition does not limit these and may include other components that do not adversely affect the desired properties of the thermoplastic composition. The sample materials which can be used as additional components will include, without limitation, pigments, antioxidants, stabilizers, surfactants, waxes, flow promoters, solid solvents, plasticizers, nucleating agents, particles and aggregates to improve the processing of the thermoplastic composition. If such additional components are included in the 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 percentages by weight are based on the amount of total weight of the aliphatic polyester polymer, the polyolefin microfiber and the compatibilizer present in the thermoplastic composition.

The thermoplastic composition of the present invention is generally simply a mixture of the aliphatic polyester polymer, polyolefin microfibers, compatibilizer, and optionally, any additional components. In order to achieve the desired properties for the thermoplastic composition of the present invention it is desirable that the aliphatic polyester polymer, the polyolefin microfibers and the compatibilizer remain essentially if reacted with each other. As such, each aliphatic polyester polymer, polyolefin microfibers, and compatibilizer remain distinct components of the thermoplastic composition. Further, it is desired that the aliphatic polyester polymer forms an essentially continuous phase and that the polyolefin microfibers form an essentially discontinuous phase, wherein the continuous phase of the aliphatic polyester polymer essentially encloses the polyolefin microfibers within its structure. As used herein, the term "enclose" and related terms are intended to mean that the continuous phase of aliphatic polyester polymer essentially encloses or surrounds the polyolefin microfibers.

In an embodiment of the present invention after the dry blending of the aliphatic polyester polymer of the polyolefin microfibers and the compatibilizer together to form a dry blend of thermoplastic composition, the dry blend of thermoplastic composition is beneficially agitated, moved or otherwise mixed to uniformly mix the aliphatic polyester polymer, the polyolefin microfibers, and the compatibilizer so that an essentially homogeneous dry mixture is formed. The dry mix can then be mixed with melt in, for example, an extruder, to effectively mix uniformly the aliphatic polyester polymer, polyolefin microfibers and compatibilizer so that an essentially homogeneous melt mixture is formed. The melted mixture, which is essentially homogeneous, can then be cooled and pelletized. Alternatively, the essentially homogeneous melt mixture can be sent directly to a spin pack or other equipment to form fibers or a non-woven structure.

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

The present invention is also directed to a multicomponent fiber which is prepared from the thermoplastic composition of the present invention. For purposes of illustration only, the present invention will generally be described in terms of a multicomponent fiber which comprises only three components. However, you should understand that the scope of the present invention is intended to include fibers with three or more components. In one embodiment, the thermoplastic composition of the present invention can be used to form the sheath of a multicomponent fiber while a polyolefin, such as polypropylene or polyethylene, is used to form the core. Structural geometries suitable for multi-component fibers include cake form or side-by-side configurations.

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

Typical conditions for thermal processing of various components include using a cut rate that is beneficially between about 100 seconds "1 about 10000 seconds" 1, more beneficially about 500 seconds "1 to about 5000 seconds "1, suitably from about 1000 seconds" 1 to about 2000 seconds "1, and more suitably to about 1000 seconds" 1. Typical conditions for thermally processing the components also include using a temperature that is beneficially between about 100 ° C to about 500 ° C, more beneficially between about 150 ° C to about 300 ° C and suitably from about 175 ° C to about 250 ° C. multicomponent are well known and do not need to be described here in detail, and melt spinning of the polymers includes the production of continuous filament such as a yarn with attached or blown co melt. or and the non-continuous filament, such as artificial and short fiber structures. To form a coiled or meltblown bonded fiber, generally, a thermoplastic composition is extruded and fed into a 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 non-woven. Meanwhile, to produce the artificial or short fiber, rather than being formed directly into a non-woven structure, the spun fiber is cooled , solidified and pulled, generally by means of a system of mechanical rollers to an intermediate filament diameter d and is collected. Subsequently the fibr can be "cold-pulled" at a temperature below the softening temperature, to the desired finished fiber diameter and is crimped or textured and cut into a desirable length of fiber.

The cooling process of a thermoplastic composition extruded at room temperature is usually achieved by blowing the air at ambient or sub-ambient temperature over the extruded thermoplastic composition. It may be mentioned 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.

Multicomponent fibers can be cut into relatively short lengths, such as short fibers which will generally have lengths in the range of about 25 to about 50 millimeters and staple fibers which are even shorter and generally have shorter lengths around 18 mm. See, for example, U.S. Patent No. 4,789,592 issued to Taniguchi others, and U.S. Patent No. 5,336,552 issued to Strack et al., Both of which are hereby incorporated by reference in their entirety.

The multicomponent fibers resulting from the present invention 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 and 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 the initial response of a material to a liquid such as water. The recessive contact angle generally gives a measure of how a material will behave over the duration of a first insult or exposure to liquid, as well as over the following insults. A lower recessive contact angle means that the material is becoming more hydrophilic during exposure to the liquid generally so it will be able to transport the liquids more consistently. The recess contact angle data is used to establish the highly hydrophilic nature of a multicomponent fiber of the present invention even though it is preferable that a decrease in the advancing contact angle of the multicomponent fiber also occurs.

Therefore, in one embodiment of the present invention, it is desired that the thermoplastic composition or multicomponent fibr exhibit a Contact Angle value which is Beneficially less than about 55 degrees more beneficially than less than about 40. degrees suitably less than about 25 degrees, suitably less than about 20 degrees, and suitably less than about 10 degrees, wherein the contact angle is determined by the method described in the section of test methods given here.

Typical aliphatic polyester based materials often undergo heat shrinkage during downstream thermal processing. Heat shrinkage mainly occurs due to the thermally induced decay of the polymer segments in the amorphous phase and in the incomplete crystalline phase. In order to overcome this problem, it is generally desirable to maximize the crystallinity of the material before the joining phase so that the thermal energy goes directly to the melt rather than allowing a chain relaxation and a rearrangement of 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 co-heat settling upon reaching a bonding roll, the fibers will not shrink essentially because such fibers are already fully oriented. The present invention alleviates the need for this additional processing step due to the morphology of the multicomponent fiber of the present invention. As discussed above, polyolefin microfibers generally provide a reinforcing structure which minimizes the expected heat shrinkage of the aliphatic polyester.

In one embodiment of the present invention, it is desired that the thermoplastic composition or a multicomponent fiber exhibit an amount of shrinkage as quantified by a Shrinkage with Heat 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 of shrinkage is based on the difference between the initial and final lengths of a fibr divided by the initial length multiplied by 100. The method by which the amount of shrinkage exhibited by a fiber will be determined is included in the sections of test medium established here.

The multicomponent fibers of the present invention are suitable for use in disposable products which include disposable absorbent products such as diapers, incontinent adult products, and bed pads. In catamenial devices such as sanitary napkins and tampons; and other absorbent products such as cleansers, bibs, wound dressings, and surgical covers or layers. Therefore, in another aspect, the present invention relates to a disposable absorbent product comprising the multi-component fibers of the present invention.

In an embodiment of the present invention, multicomponent fibers are formed in a fibrous matrix for incorporation into a disposable absorbent product. A fibrous matrix can take the form of, for example, a fibrous woven fabric. The fibrous non-woven fabrics can be made entirely of multicomponent fibers of the present invention or can be mixed with other fibers. The length of the fibers used may depend on the particular end use contemplated. Where the fibers are to be degraded in water, for example in a toilet, it is advantageous for the fibers to be maintained at or below about 15 millimeters.

In one embodiment of the present invention, disposable absorbent product is provided, which is a disposable absorbent product comprising a liquid-permeable upper sheet, a lower sheet attached to the liquid-permeable upper sheet, and an absorbent structure placed therein. liquid permeable upper sheet and lower sheet, e wherein the lower sheet comprises multicomponent fibers of the present invention.

Exemplary disposable absorbent products are generally described in U.S. Patent Nos. US-A-4, 710, 187; US-A-4, 762, 521; US-A 4,770,656; and US-A-4-798, 603; whose references are incorporated herein 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. Therefore, absorbent products and structures are desirably capable of absorbing multiple insults from body fluids in amounts at which products and absorbent structures will be exposed during use. Insults are usually separated from each other by a period of time.

Test methods Melting temperature The melting temperature of a material is determined using differential scanning calorimetry. A differential scanning calorimetry, under the designation d Thermal Analyst 2910 Differential Scanning Calorimeter, was equipped with a liquid nitrogen cooling accessory and was used in combination with a Therma Analyst 2200 analysis program (version 8.10) available from T.A. Instruments Inc. of New Castle, Delaware, which was used for the determination of melting temperatures.

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

The differential scanning calorimeter s calibrated using an Indian 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. The entire test was run with 55 cubic centimeters / minute of nitrogen purge (industrial grade) on the test chamber. The heating and cooling program is a cycle two test that begins with the chamber balancing at -75 ° C, followed by the heating cycle from 20 ° C / minute to 220 ° C, followed by the cooling cycle at 20 ° C / minute at -75 ° C and then another heating cycle at 20 ° C / minute at 220 ° C.

The results are evaluated using the analysis software program where the glass transition temperature (Tg) of the inflection, endotherm 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 a calculation? automatic inflection Apparent viscosity A capillary rheometer, under the designation Góttfer Rheograph capillary rheometer 2003, which was used in combination with the inRHEO analysis program (version 2.31) both available from the 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 pressure transducer of 2000 bar and 30 millimeters long / 30 millimeters active length / or millimeter diameter / 0 millimeters height / 180 degrees d run at an angle, around the capillary matrix orifice If the sample of material being tested shows or is known to have sensitivity to water, the sample of material is dried in a vacuum oven above the transition temperature of the glass, for example above 55 ° C to 60 ° C. materials of poly (lactic acid) under a vacuum of at least 15 inches of mercury with a purge of nitrogen gas of at least 30 standard cubic feet per hour for at least 16 hours.

Once the instrument is warmed and the pressure transducer is calibrated, the material sample is incrementally loaded into the column, packing the resin in the column with one rod at a time to ensure consistent melting during the test. After loading the sample of material, a melting time of two minutes precedes each test to allow the material sample to fully melt the test temperature. The capillary rheometer automatically takes data points and determines the apparent viscosity (in Pascal .second) at seven apparent cutoff rates (in second "1): 50, 100, 200, 500, 1000, 2000, and 5000. When examined The resulting curve is important if the curve is relatively smooth.If there are standard deviations of a general curve from one point to another, possibly due to air in the column, the running test should be repeated to confirm the results.

The rheology curve resulting from the apparent shear rate versus apparent viscosity gives an indication of how the material sample will run at that temperature in an extrusion process. The apparent viscosity values at a cut rate of at least one thousand seconds "1 are of specific interest because these typical conditions are found in commercial fiber spinning extruders.

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

The gel permeation chromatography is put together with two analytical columns in series two PL gel mixed linear K 5 microns, 75 x 300 millimeters. The temperatures of the detector column are 30 ° C. The mobile phase is tetrahydrofuran d class (THF) of high performance liquid chromatography (HPLC). The pump rate is 0.8 millimeters per minute with an injection volume of 25 microliters. The total corrid time is 30 minutes. It is important to note that the new analytical columns should be installed every four months, a new guard column almost every month and a new filter online almost every month.

Polystyrene polymer standards, obtained from Aldrich Chemical Company, should be mixed in a dibloromethane (DCM): THF (10:90) solvent, both HPLC-class, in order to obtain concentrations of lmg / L. Multiple polystyrene standards they can be combined in a standard solution as long as their peaks do not overlap when they are chromatographed. A range of standards of around 687,400,000 molecular weight should be prepared. Examples of standard blends with Aldrich polystyrene of molecular weights by varying weight include Standard 1 (401,340, 32,660 2,727), Standard 2 (45,730, 4,075), Standard 3 (95,800, 12,860) Standard 4 (184,200, 24,150, 687 ).

Then prepare the supply verification standard. Dissolve 10 grams of a 200,000 molecular weight poly (acid lactic acid) standard, catalog No. 1924 obtained from Polysciences Inc., in 100 ml of HPLC-type DCM to a glass jar with a lined lid using an orbital shake (per at least 30 minutes). Pour the mixture on a dry and clean glass plate and let the solvent evaporate first, then place in a preheated vacuum oven at 35 ° C and dry for about 14 hours under a vacuum of 2 millimeters of mercury. Then, remove the poly (lactic acid) from the oven and cut the film into small strips. Immediately grind the samples using a grinding mill (with a 10 mesh grid) taking care not to add too much sample causing the mill to freeze. Store a few grams of the ground sample in a dry glass jar in a desiccator, while the rest of the sample can be stored in the freezer in a jar of similar type.

It is important to prepare a new verification standard before the start of each new sequence, because the molecular weight is greatly affected by the sample concentration, care should be taken of its heavy preparation. To prepare the standard of verification weigh the reference standard of poly (lactic acid) molecular weight by weight of 0.0800g ± 0.0025g of 200,000 in a dry and clean scintillation recipient. Then, use a volumetric pipette or a dedicated repipet, add 2 ml of DCM to the container and screw the lid tightly. Allow the sample to dissolve completely. Rotate the sample on an orbital shaker, such as a mixer such as a Thermolin Roto Mix (type 51300) or a similar mixer if necessary. To assess whether it dissolved, hold the vessel to light at a 45 ° angle. Turn it slowly and look at the liquid as it flows down the glass. If the bottom of the container does not appear smooth, the sample is not completely dissolved. It can take the sample several hours to dissolve. Once it has dissolved, add 18 ml of THF using a volumetric pipette or a dedicated repipet, cover the rinse tightly and mix.

Sample preparations begin by weighing 0.0800g + 0.0025g of the sample in a clean, dry scintillation container (great care must be taken in weighing and in preparation). Add 2 milliliters of DCM to the container with a volumetric pipette or a dedicated repipet screw the cap tightly. Allow the sample to dissolve completely using the same technique described in the preparation of the above mentioned verification standard. After adding 18 ml of THF using a volumetric pipette a dedicated repipet, screw the cap tightly mix.

Begin the evaluation by doing a test injection of a standard preparation to test the equilibrium of the system. Once the balance is confirmed, inject the standard preparations. After those are run, first inject the standard preparation d verification and then the sample preparations. Inject the standard preparation of verification every seven injections d sample and at the end of the test. Be sure not to take more than two injections of any container and those injections should be done 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 of regression calculated for standard must not be less than 0.950 and not more than 1.050. Second, the relative standard deviation of all molecular weights by weight of the standard verification preparations n should be more than 5.0%. Third, the average molecular weight weights of standard injections of standard preparation verification should be within 10 molecular weight by weight over the first injection standard preparation check. Finally, record the lactide response for the 200 micrograms per milliliter (μg / mL) of standard injection on a SQC data graph. Using the graph control lines, the response must be within the defined SQC parameters.

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

Heat shrinkage of fibers The equipment required for the determination of heat shrinkage includes: a convection oven (Thelco Model 160DM laboratory furnace available from Precision Scientific Inc., Chicago Illinois), sinker weights of 0.5 g (+/- 0.06 g), half-inch binder fasteners, binding tape, graph paper with at least one-quarter inch squares, a foam poster board (11 x 14 inches) or an equivalent substrate to hold the graph paper in the samples. The convection oven must be capable of a temperature of around 100 ° C.

The fiber samples are melt spun and their respective spinning conditions. In general, a bundle of 3 filaments is preferred and mechanically pulled to obtain fibers with a better stretch ratio of jet 224. Only the fibers of my jet stretch ratio can be compared to one another in relation to their shrinkage with heat. The ratio d of jet stretching of a fiber is the speed ratio of the pull roller down divided by the linear extrusion rate (distance / time) of the melted polymer leaving the spinning organ. Spun fiber is usually collected on a reel using a reel. The collected fiber bundle was separated into 30 strands, if a bundle of 30 filaments has not already been obtained, and cut into 9-inch stretches.

The graph paper is curled over the poster board where one edge of the graph paper is matched with the edge of the poster board. One end of fiber bundle is curb, for not more than an inch of end. The tapered end is attached to the poster board at the edge where the graph paper is matched so that the edge of the bra rests on one of the horizontal lines of the graph paper while the bundle of fiber is held in place. (The taped end should be barely visible when secured under the bra). The other end of the bunch is pulled tightly and aligned parallel to the vertical lines on the graph paper. Then, 7 inches down from the point where the fastener is joining the fiber, pinch or sink 0.05g around the bundle of fiber. Repeat the clamping process for each duplicate. Usually, 3 duplicates can be attached at the same time. The marks can 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 hang vertically and do not touch the board. At intervals d of 5, 10 and 15 minutes quickly mark the new place d sinkers on graph paper and return the sample to the oven.

After the test is completed, remove the board and measure the distances between the origin (where the fastener holds the fibers and marks at 5, 10, and 15 minutes with a 1/16 inch graduated ruler. per sample Calculate the averages, the standard deviations and the percentage of shrinkage The percentage of shrinkage is calculated, (initial length / length measured divided by the initial length and multiplied by 100. As reported in the examples used here and as Through the claims, the heat shrinkage 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 by agreement. to the preceding test method.

Contact angle The equipment includes a dynamic contact angle analyzer DC-322 and a WinDCA program (version 1.02, both available from ATI-CAHN Instruments, Inc., of Madison Wisconsin.) The test was done on the "A" circuit with a weighted scale. The calibrations must be done monthly on the motor and daily on the balance (mass of 100 mg used) as indicated in the manual.

The thermoplastic compositions are spun into fibers and the free fall sample (zero jet 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 is attached to the wire hanger with scotch tape so that 2-3 centimeters of fiber extends beyond the end of the hanger. Then the fiber sample is cut with a razor so that 1.5 centimeters are extending beyond the end of the hanger. An optical microscope is used to determine the average diameter (3 to 4 measurements) along the fiber.

The sample on the wire hanger was suspended from the agitated scale on circuit A. The immersion liquid is distilled water and was changed for each specimen. The specimen parameters are entered (for example fiber diameter) and the test was started. The phase advances to 151.7 microns / second until the depth of zero d immersion is detected when the fiber makes contact with the surface of distilled water. From the depth of zero immersion the fibr advances to the water for one centimeter, remains for seconds and then immediately backs off one centimeter. E autoanalysis of the contact angle made by the program determines the forward and backward contact angles of the fiber sample based on the standard calculations identified in the manual. The contact angles of zero or d < 0 indicate that the sample has been completely wetted. S tested 5 duplicates for each sample and a statistical analysis for the main standard deviation, and the coefficient of d percent variation was calculated. As reported in the examples given here and as used in the claims, the value of the contact angle and the avanc represents the contact angle of the water distilled on a sample of finished fiber according to the test method. of precedent. Similarly, as reported in the examples given herein and as used by the claims, the contact angle value of backs represents the back contact angle of the distilled water on a fiber sample determined according to the test method. precedent Examples Example 1 The fibers were prepared using variable amounts of poly (lactic acid), a polypropylene and a compatibilizer. The poly (lactic acid) polymer (PLA) s obtained from Chronopol Inc., of Golden Colorado, and had a L: D ratio of 100 to 0, a melting temperature of about 175 degrees centigrade, an average molecular weight. of weight of about 181,000, an average molecular weight d number of about 115, 000, a Polydispersity Index d about 1.57 and a residual lactic acid monomer value of about 2.3 percent by weight. The propylene polymer (PP) was obtained from Himont Incorporated under the designation polymer polypropylene PF305, which had a specific gravity of between about 0.88 to about 0.92 and a melting temperature of about 160 degrees centigrade. The compatibilizer was obtained from Petrolit Corporation of Tulsa Oklahoma, under the designation ethoxylated alcohol UNITHOX® 480, which had a melted temperature of about 160 degrees centigrade and a number average molecular weight of about 2,250.

To prepare the specific thermoplastic composition, the various components were first mixed and dried and then mixed with melted in a counter-rotating gemel screw to provide vigorous mixing of the components. Melting mixing involves the partial or complete melting of the components combined with the cutting effect of the rotating mixing screws. Such conditions are conducive to optimum mixing and even dispersion of the components of the thermoplastic composition. Twin screw extruders such as the Haake Rheocord 90, available from Haake GmbH of Karlsautte, Germany, or a twin screw mixer Brabender (catalog No. 05-96-000) available from Brabende Instruments of South Hackensack, New Jersey, Other comparable twin screw extruders are very suitable for this task. The melted composition is cooled by extruding the melted mixer onto either a cooled cylinder of liquid or surface and / or by forced air passed over the extrudate. The cooled composition is then pelletized for conversion to fibers.

The conversion of these resins into fiber and fabric was carried out on an extruder of 0.75 inches d diameter with a screw of 24: 1 L: (length: diameter) and three heating zones which were fed into the pipeline. transfer from the extruder which fed into the transfer pipe from the extruder to the spin pack, which constitutes the fourth heating zone and contains a static mixer unit of the Koch® SMX type of about 1. centimeters in diameter, available from Koch Engineering Compan Inc. of New York, New York and then on a spinning head (fifth heating zone) and through the spinning plate which is simply a plate with numerous small holes through which the melted polymer will be extruded. The spinning plate used here had 15 to 30 holes as each hole has 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 a temperature range of 13 degrees Celsius to 22 degrees Celsius and pulled down by a mechanical pull roller and passed over either a furling unit for harvesting or a fiber pulling unit for a joint formation with spinning and bonding or through an accessory equipment for settling with heat or other treatment before harvesting.

The fibers were evaluated for the contact angle and the heat shrinkage. The composition of the various fibers and the results of the evaluations are shown in Table 1. TABLE 1 Composition, Fiber (% by Step) Angle of Contact Sample # PIA PP Compatibilizer Advancing Backing Heat Encocration 100% 85.3 ° 40.7 ° 34 % * 2 100% 128.1 ° 93.9 ° 0% * 3 --- 95% 5% 120.6 ° 79 ° ... * 4 --- 95% 5% 124.0 ° 58.5 ° 0% * 5 95% - .. 5 % 89.2 ° 10.0 ° - * 6 70% 30% --- 92.3 ° 56.5 ° 0% 7 55% 37% 8% 111.7 ° 51.4 ° 0% 8 64% 27% 9% 0% 9 48% 39% 13% 106.3 ° 0 ° 0% 10 52% 35% 13% 97.6 ° 16.8 ° 0% 11 61% 26% 13% 88.6 ° 5.8 ° 0% 12 70% 17% 13% 86.7 ° 0 ° 0% 13 51% 34% 15% 92.8 ° 3.3 ° 0% 14 76.5% 8.5% 15% 86.1 ° 0 ° 0% It is not an example of the present invention.

Example 2 The fibers were prepared using several amounts of polybutylene succinate, a polypropylene and a compatibilizer. Polybutylene succinate (PBS) was obtained from Showa Highpolymer Company Limited of Tokyo Japan, under the designation polybutylene succinate Bionolle 1020, and had a melting temperature of about 95 degrees centigrade, a weight average molecular weight of between about 40.00 to about 1 '000, 000, an average molecular weight of number d between about 20,000 to about 300,000 and a Polydispersity Index of between about 2 to about 3.3. Polypropylene polymer (PP) was obtained from Himont Incorporate under the designation of polypropylene polymer PF 305 which had a specific gravity of between about 0.88 to about 0.92 and a melting temperature of about 160 degrees centigrade. The compatibilizer was obtained from Petrolit Corporation of Tulsa Oklahoma under the designation ethoxylated alcohol UNITHOX® 480, which had a melted temperature of about 160 degrees centigrade and an average molecular weight of about 2,250.

The fibers were prepared using a method essentially similar to the method described in Example 1.

The fibers were evaluated for contact angle and shrinkage with heat. The composition of the vari fibers and the results of the evaluations is shown in Table 2.

TABLE 2 Fiber Composition (% by Weight) Contact Angle Sample # PIA PP Compatibilizer Advancing by Heat * 15 100% --- --- 76 ° 0% 16 61% 26% 13% 21.8 ° 0% 17 70% 17% 13% 24.1 ° 0% It is not an example of the present invention. 3 The fibers were prepared using varying amounts of poly (lactic acid), a polyethylene and compatibilizer. The poly (lactic acid) polymer (PLA) obtained from Chronopol, Inc., of Golden Colorado, and had a L: D ratio of 100 to 0, a melting temperature of about 175 degrees centigrade, an average molecular weight of weight about 181,000, an average molecular weight number of about 115,000, a Polydispersity Index about 1.57 and a residual lactic acid monomer value of about 2.3 percent by weight. Polyethylene (PE) polymer was obtained from Dow Chemical Company, of Midlan Michigan, under the designation ASPUN® P 6811A polyethylene polymer and had a melting temperature of about 13 degrees centigrade. The compatibilizer was obtained from the Petrolite Corporation of Tulsa Oklahoma, under the designation ethoxylated alcohol UNITHOX® 480, which had a melted temperature of about 160 degrees centigrade and a number average molecular weight of about 2,250.

The fibers were prepared using the method essentially similar to the method described in Example 1.

The fibers were evaluated for contact angle and shrinkage with heat. The composition of the various fibers and the results of the evaluations is shown in Table 3.

TABLE 3 Fiber Composition (% by Weight) Contact Angle Sample # PIA PP Compatibilizer Advancing Backing Heat Shrinkage 18 52% 35% 13% 0 ° 2% 19 78% 9% 13% 66.3 ° 0 ° 9% It is not an example of the present invention.

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

Claims (33)

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

1. A thermoplastic composition comprising to. an aliphatic polyester polymer in a weight amount that is between about 45 to about 90 percent by weight, wherein the aliphatic polyester polymer forms an essentially continuous phase; b. polyolefin microfibers in a weight range 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 an essentially discontinuous enclose within an essentially continuous phase of aliphatic polyester polymer; Y c. a compatibilizer which exhibits a hydrophilic-lipophilic balance ratio which is from about 10 to about 40, in an amount by weight which is from about 7 to about 25 percent by weight, wherein all percent by weight Weight are based on the total weight amount of the aliphatic polyester polymer; the polyolefin microfibers and the compatibilizer present in the thermoplastic composition.

2. The thermoplastic composition 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, mixture of such polymers and copolymers of such polymers.

3. The thermoplastic composition as claimed in clause 2 characterized in that the aliphatic polyester polymer is poly (lactic acid).

4. The thermoplastic composition as claimed in clause 1 characterized in that the polyolefin is selected from the group consisting of copolymer homopolymers comprising repeating units selected from the group consisting of ethylene, propylene, butene, hexene pentene, heptene, octene, 1, 3-butadiene, and 2-methyl-1,3-butadiene

5. The thermoplastic composition as claimed in clause 4, characterized in that the polyolefin is selected from the group consisting of polyethylene and polypropylene.

6. The thermoplastic composition as claimed in clause 1 characterized in that the polyolefin microfibers have a diameter that is less than about 25 microns.

7. The thermoplastic composition as claimed in clause 1 characterized in that the polyolefin microfibers are present in an amount of weight that is d between about 5 to about 40 percent by weight.

8. The thermoplastic composition as claimed in clause 1 characterized in that the compatibilizer is an ethoxylated alcohol.

9. The thermoplastic composition as claimed in clause 1 characterized in that the thermoplastic composition exhibits a receding contact angle value that is less than about 55 degrees.

10. The thermoplastic composition 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, mixture 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 an amount by weight that is between about d 5 to about 40 percent by weight; the compatibilizer is ethoxylated alcohol; and the thermoplastic composition exhibits a recoil contact angle value that is less than about 55 degrees.

11. The thermoplastic composition 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 multicomponent fiber prepared from a thermoplastic composition, wherein the thermoplastic composition comprises: to. an aliphatic polyester polymer in a weight amount that is between about 45 to about 90 percent by weight, wherein the aliphatic polyester polymer forms an essentially continuous phase; b. polyolefin microfibers in an amount of weight that is from greater 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 an essential phase discontinuous enclosed within the essentially continuous phase of aliphatic polyester polymer; Y c. a compatibilizer, which exhibits a hydrophilic-lipophilic balance ratio of around 10 to about 40, in an amount of weight ranging from about 7 to about 25 percent by weight, and where all percent 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 multicomponent fiber exhibits a receding contact angle value that is less than about 55 degrees.

13. The multicomponent fiber as claimed in clause 12 characterized by multi-component fiber exhibits a shrinkage value with heat that is less than about 10 percent.

14. The multicomponent fiber as claimed in clause 12 characterized in that the aliphatic polyester polymer is selected from the group consisting of poly (lactic acid), polybutylene succinate, succinate-co-polybutylene adipate, polyhydroxybutyrate-co-valerate, polycaprolactone, sulfonated polyethylene terephthalate, mixture of such polymers and copolymers of such polymers.

15. The multicomponent fiber as claimed in clause 14 characterized in that the aliphatic polyester polymer is poly (lactic acid).

16. The multicomponent fiber as claimed in clause 12 characterized in that the polyolefin is selected from the group consisting of copolymer homopolymers 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 multicomponent fiber as claimed in clause 16 characterized in that the polyolefin is selected from the group consisting of polyethylene and polypropylene.

18. The multicomponent fiber as claimed in clause 12 characterized in that the polyolefin microfibers have a diameter that is less than about 25 microns.

19. The multicomponent fiber as claimed in clause 12 characterized in that the polyolefin microfibr is present in an amount of weight that is between about 5 to about 40 percent by weight.

20. The multicomponent fiber as claimed in clause 12 characterized in that compatibilizer is an ethoxylated alcohol.

21. The multicomponent fiber 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-c adipate, polyhydroxybutyrate-co-valerate polycaprolactone, terephthalate sulfonated polyethylene, mixture 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 to about 40 percent by weight; the compatibilizer is ethoxylated alcohol; and the multicomponent fiber exhibits a value of shrinkage by heat that is less than about 10 percent.

22. The multicomponent fiber 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 disposable absorbent product comprising a liquid permeable topsheet, a lower blade joined to the topsheet, and an absorbent structure positioned between the liquid permeable topsheet and the lower blade, wherein the bottom sheet comprises a multicomponent fiber prepared of a thermoplastic composition, wherein the thermoplastic composition comprises: to. an aliphatic polyester polymer in a weight amount that is between about 45 to about 90 percent by weight, wherein the aliphatic polyester polymer forms an essentially continuous phase; b. polyolefin microfibers in a weight range 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 an essentially discontinuous within the essentially continuous phase of aliphatic polyester polymer; and c. a compatibilizer, which exhibits a hydrophilic-lipophilic balance ratio of around 10 to about 40, in an amount of weight ranging from about 7 to about 25 percent by weight, and where all percent 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 multicomponent fiber exhibits a receding contact angle value that is less than about 55 degrees.

24. The disposable absorbent product as claimed in clause 23 is characterized in that the multicomponent fiber exhibits a heat shrink value that is less than about 10 percent.

25. The disposable absorbent product 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.

26. The disposable absorbent product as claimed in clause 25 characterized in that the aliphatic polyester polymer is poly (lactic acid).

27. The disposable absorbent product as claimed in clause 23 is 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.

28. The disposable absorbent product as claimed in clause 27 is characterized in that the polyolefin is selected from the group consisting of polyethylene and polypropylene.

29. The disposable absorbent product as claimed in clause 23 is characterized in that the polyolefin microfibers have a diameter that is less than about 25 micrometers.

30. The disposable absorbent product as claimed in clause 23 is characterized in that the polyolefin microfibers are present in an amount by weight that is between about 5 to about 40 percent by weight.

31. The disposable absorbent product as claimed in clause 23 is characterized in that the compatibilizer is an ethoxylated alcohol.

32. The disposable absorbent product 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, mixture 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 to about 40 percent by weight; the compatibilizer is ethoxylated alcohol; and the multicomponent fiber exhibits a value of shrinkage by heat that is less than about 10 percent.

33. The disposable absorbent product as claimed in clause 32 is characterized in that the aliphatic polyester polymer is poly (lactic acid) and the polyolefin is selected from the group consisting of polyethylene and polypropylene. SUMMARY A thermoplastic composition comprising an unreacted mixture of an aliphatic polyester polymer as a continuous phase, polyolefin microfibers with a discontinuous phase enclosed within the continuous phase of aliphatic polyester polymer, and a compatibilizer for the aliphatic polyester polymer is disclosed. and polyolefin microfibers. Multicomponent fiber exhibits substantial biodegradable properties and good wettability but is easily processed. The thermoplastic composition is useful for making n-woven structures that can be used in disposable absorbent products that are intended for the absorption of fluids such as fluids. of the body.