MX2008007610A - Biodegradable multicomponent fibers - Google Patents

Abstract

A multicomponent fiber that contains a high-melting aliphatic polyester and a low-melting aliphatic polyester is provided. The multicomponent fibers are substantially biodegradable, yet readily processed into nonwoven structures that exhibit effective fibrous mechanical properties.

Description

FIBERS OF MULTIPLE BIODEGRADABLE COMPONENTS Background of the Invention Disposable absorbent articles generally contain absorbent fibrous fabrics, such as carded fabrics attached or laid with air. Such tissues are often stabilized with binder fibers during tissue formation. More specifically, the binder fibers are usually multi-component fibers with a significant difference, for example at least 20 ° C, in melting temperature between the lower casting and higher casting components. The fibers are therefore heated to a temperature sufficient to melt the lower cast components, but not the upper cast components. Several binder fibers have been developed that are biodegradable to improve discarding of the absorbent article. Many commercially available biodegradable polymers are formed from aliphatic polyester materials. Although the fibers prepared from aliphatic polyesters are known, problems have been encountered with their use. For example, aliphatic polyesters have a relatively low crystallization rate compared to polyolefin polymers, so they often result in poor processability. Most aliphatic polyesters also have melting temperatures much lower than polyolefins and are difficult to sufficiently cool them followed by thermal processing. Additionally, many aliphatic polyesters (e.g., polylactic acid) experience severe hot shrinkage due to the relaxation of the polymer chain during the downstream heat treatment process, such as thermal bonding and lamination. Therefore, biodegradable binding fibers were developed in response to these and other problems. One such binder fiber is described in U.S. Patent No. 6,177,193 issued to Tsai et al. Tsai binder fiber and others is formed of two components, one of which is a mixture of a multicarboxylic acid, aliphatic polyester, and a wetting agent. Multicarboxylic acid is required to reduce polymer viscosity for processing, as well as to facilitate crystallization (eg, nucleating agent) during immersion. A problem with such fibers, however, is that they require a manufacturing process that is relatively complex and inefficient. Additionally, the fibers are also weak and have a relatively low tensile strength.

As such, there is presently a need for a fiber that is biodegradable and easy to process into fibrous structures exhibiting good mechanical properties.

Synthesis of the Invention In accordance with an embodiment of the present invention, a biodegradable multi-component fiber is described. The fiber comprises a first component containing at least one higher melting point aliphatic polyester having a melting point of about 160 ° C and about 250 ° C. The fiber also comprises a second component that contains at least one aliphatic polyester of lower melting point, the melting point of the lower melting point aliphatic polyester is at least about 30 ° C less than the melting point of aliphatic polyester knitted upper casting. The lower melting point aliphatic polyester has a number average molecular weight of from about 30,000 to about 120,000 Daltons and an apparent viscosity of from about 50 to about 215 Pascal-seconds, as determined at a temperature of 16 ° C. ° C and a cutting rate of 1000 sec "1. The present inventors have discovered that polymers having this particular combination of molecular weight and viscosity may possess improved processability without adversely affecting the strength and bonding capacity of the fiber that result.

Other features and aspects of the present invention are described in more detail below.

Brief Description of the Drawings A complete and capable description of the present invention, which includes the best mode thereof, addressed to one of ordinary skill in the art, is disclosed more particularly in the remainder of the application, which refers to the figures appended hereto. which: Figure 1 is a schematic illustration of a process that can be used in an embodiment of the present invention to form multi-component fibers; Figure 2 shows electron microscopy micrographs (40X) of two fiber samples formed in Example 3, wherein Figure 2a shows Sample No. 13 and Figure 2b shows Sample No. 12; Fig. 3 is a graph describing strip tensile strength versus bonding temperature for knitted knitted fabrics of Example 5 having a basis weight of 25 grams per square meter; Figure 4 is a graph describing the strength versus the elongate percentage for knitted fabrics of Example 5 having a basis weight of 25 grams per square meter; Y Figure 5 is a perspective view of an absorbent article that can be formed in accordance with an embodiment of the present invention.

The repeated use of reference characters in the present application and in the drawings is intended to represent the same or analogous features or elements of the invention.

Detailed Description of Representative Incorporations Reference may now be made in detail to several embodiments of the invention, one or more examples of which are disclosed below. Each example is provided by way of explanation of the invention, not limitation of the invention. In fact, it may be apparent to those skilled in the art that various modifications and variations may be made in the invention without departing from the scope or spirit of the invention. For example, the features illustrated or described as part of an embodiment may be used in another embodiment to still yield a further embodiment. Therefore, it is the intention that the present invention covers such modifications and variations as fall within the scope of the appended claims and their equivalents.

Definitions As used herein, the term "biodegradable" or "biodegradable polymer" generally refers to a material that degrades from the action of naturally occurring microorganisms, such as bacteria, fungus, and algae; the heat of the environment; humidity; or other factors of the environment. The biodegradability of a material can be determined using Test Method ASTM 5338.92.

As used herein, the term "fibers" refers to elongated extrudates formed by passing a polymer through a forming orifice such as a matrix. Unless otherwise noted, the term "fibers" includes discontinuous strips having a defined length and continuous strips of material, such as filaments.

As used herein, the term "multiple components" refers to fibers formed from at least two polymer components (e.g., bicomponent fibers).

As used herein, the term "nonwoven fabric" refers to a fabric having a structure of individual fibers or threads that are interlocked, but not in an identifiable manner as in a knitted fabric. Non-woven fabrics include, for example, meltblown fabrics, spunbond fabrics, fabrics carded, wet stretched fabrics, air laid fabrics, coform fabrics, fabrics and hydraulically entangled, et cetera.

As used herein, the term "bonded carded fabric" refers to a fabric made of basic fibers that are sent through a carding or combing unit, which separates or breaks apart and aligns the basic fibers in the direction of machine for forming a fibrous nonwoven fabric generally oriented in the machine direction. Such fibers are usually obtained in bales and placed in an opener / mixer or picker, which separates the fibers before the carding unit. Once formed, the tissue is then joined by one or more known methods.

As used herein, the term "air-laid fabric" refers to a fabric made of bundles of fibers that typically have lengths in the range from about 3 to about 19 millimeters (mm). The fibers are separated, placed in a supply of air, and then deposited on a forming surface, usually with the assistance of a vacuum supply. Once formed, the tissue is then joined by one or more known methods.

As used herein, the term "coform fabric" generally refers to a composite material containing a stabilized binder or binder of fibers of thermoplastics and a second non-thermoplastic material. As an example, coform materials can be made by a process in which at least one melt blown die head assembly is arranged near a channel through which other materials are added to the fabric while it is forming. Such other materials may include, but not limited to, fibrous organic materials such as non-wood or wood pulp such as cotton, rayon, recycled paper, pulp fluff and also super-absorbent particles, materials inorganic and / or organic absorbers, the polymeric basic fibers treated and so on. Some examples of such coform materials are described in U.S. Patent Nos. 4,100,324 issued to Anderson et al .; 5,284,703 granted to Everhart and others; and 5,350,624 granted to Georger and others; which are incorporated herein in their entirety by reference to the same for all purposes.

Detailed description The present invention is directed to a biodegradable multi-component fiber containing a first component formed of at least one higher melting aliphatic polyester and a second component formed from at least one lower melting aliphatic polyester component. The first and second components can be arranged in any desired configuration to form multi-component fibers according to the present invention. The configuration of such materials can be, for example, a pod the core, side by side, pie, islands in the sea, and so on. The resulting multi-component fibers are substantially biodegradable, yet rapidly processed into fibrous structures exhibiting good mechanical properties.

I. First Component As mentioned, the first multi-component fiber component is formed of one or more biodegradable "top melting point" aliphatic polyesters. Typically, the melting point of such polyesters is from about 160 ° C to about 250 ° C, in some incorporations from about 170 ° C to about 240 ° C, and in some additions, from about 180 ° C. up to around 220 ° C. Various "top casting" aliphatic polyesters may be employed in the present invention, such as polyesteramides, modified polyethylene terephthalate, polylactic acid (PLA), terpolymers based on polylactic acid, polyglycolic acid, polyalkene carbonates (such as polyethylene carbonate), polyhydroxyalkanoates (PHA), polyhydroxybutyrate (PHB), polyhydroxyvalerate (PHV), and copolymers of polyhydroxybutyrate-hydroxyvalerate (PBV).

The term "polylactic acid" generally refers to the homopolymers of lactic acid, such as poly (L-lactic acid), poly (D-lactic acid), poly (DL-lactic acid), mixtures thereof , and copolymers containing lactic acid as the predominant component and a small part of a copolymerizable comonomer, such as 3-hydroxybutyrate, caprolactone, glycolic acid, and the like.

Any known polymerization method, such as polycondensation or open ring polymerization, can be used to polymerize lactic acid. In the polycondensation method, for example, L-lactic acid, D-lactic acid, or a mixture thereof is directly subjected to dehydro-polycondensation. In the open ring polymerization method, a lactide which is a cyclic dimer of lactic acid and is subjected to polymerization with the aid of a catalyst and a polymerization adjusting agent: Lactide may include L-lactide (a dimer of L-lactic acid), D-lactide (a dimer of D-lactide acid), DL-lactide (a condensate of L-lactic acid and D-lactide acid), or mixtures thereof. These isomers can be mixed and polymerized, if necessary, to obtain polylactic acid having any desired composition and crystallinity. A small amount of a chain extending agent (eg, a diisocyanate compound, an epoxy compound or an anhydride acid) can also be used to increase the molecular weight of the polylactic acid.

Generally speaking, the average molecular weight of polylactic acid is in the range of about 60,000 to about 1,000,000. A particularly suitable polylactic acid polymer that can be used of the present invention is commercially available from Biomer, Inc. (Germany) under the name BiomerTM L9000. Still other suitable polylactic acid polymers are commercially available from Natureworks, LLC of Minneapolis, Minnesota.

II. Second Component The second component is formed from one or more biodegradable "lower melting point" aliphatic polyesters. Typically, such polyesters have a melting point of about 50 ° C to about 160 ° C, in some incorporations from about 100 ° C to about 160 ° C, and in some additions, from about 120 ° C to around 160 ° C. Moreover, the melting point is typically also at least about 30 ° C, at some incorporations at least about 40 ° C, and at some incorporations, at least about 50 ° C less than the point of casting of the "high melting point" aliphatic polyesters. The "lower melting point" aliphatic polyesters are useful in that they are biodegradable at a faster rate than the higher melting point polyesters. Additionally, these are generally softer to the touch than most "Top casting" aliphatic polyesters. The glass transition temperature ("Tg") of the lower melting point polyesters may also be lower than those of the higher melting point polyesters to improve the flexibility and processability of the polymers. For example, lower melting point aliphatic polyesters may have a glass transition temperature of about 25 ° C or less, in some embodiments about 0 ° C or less, and in some embodiments, about -10 ° C. or less. Such a glass transition temperature may be at least about 5 ° C, at some incorporations at least about 10 ° C, and at some incorporations, at least about 15 ° C less than the transition temperature of glass of the polyesters of top casting point.

Examples of aliphatic polyesters that may have a lower melting point and glass transition temperature include aliphatic polyesters with repeating units of at least 5 carbon atoms (for example, polyhydroxyvalerate, polyhydroxybutyrate-hydroxyvalerate copolymer and polycaprolactone), and aliphatic polymers based on succinate (for example, polybutylene succinate, polybutylene succinate adipate, and polyethylene succinate). More specific examples may include polyethylene oxalate, polyethylene malonate, polyethylene succinate, polyethylene polypropylene oxalate, polypropylene malonate, polypropylene succinate, polybutylene oxalate, polybutylene malonate, polybutylene succinate, and mixtures and copolymers of these compounds. Among these compounds, polybutylene succinate and copolymers thereof are usually preferred.

The aliphatic polyesters are typically synthesized through the condensation polymerization of a polyol and an aliphatic dicarboxylic acid or an anhydride thereof. The polyols can be substituted or unsubstituted, linear or branched, the polyols selected from polyols containing 2 to about 8 carbon atoms, polyalkylene ether glycols containing 2 to 8 carbon atoms, and the cycloaliphatic diols contained in about 4 to about 12 carbon atoms. Substituted polyols typically contain 1 to about 4 substituents independently selected from halo, C6-C? Or aryl and C?-C4 alkoxy. Examples of polyols that can be used include, but are not limited to, ethylene glycol, diethylene glycol, propylene glycol, 1,3-propanediol, 2,2-dimethyl-1,3-propanediol, 1,3-butanediol, 1 , 4-butanediol, 1, 5-pentanediol, 1,6-hexanediol, polyethylene glycol, diethylene glycol, 2, 2, 4-trimethyl-1,6-hexanediol, thiodiethanol, 1, 3- cyclohexanedimethanol, 1,4-cyclohexanedimethanol, 2,2,4,4-tetramethyl-l, 3-cyclobutanediol, triethylene glycol, and glycol of tetraethylene. Preferred polyols include 1,4-butanediol; 1,3-propanediol; ethylene glycol; 1,6-hexanediol; diethylene glycol; and 1,4-cyclohexanedimethanol. Representative aliphatic dicarboxylic acids that can be used include the non-aromatic, branched or linear, unsubstituted or substituted dicarboxylic acids selected from the aliphatic dicarboxylic acids containing 2 to about 12 carbon atoms and cycloaliphatic dicarboxylic acids containing about 5 to around 10 carbon atoms. Substituted non-aromatic dicarboxylic acids may typically contain 1 to about 4 substituents selected from halo, C 1 -Cio aryl, and C 4 -C 4 alkoxy. Non-limiting examples of cycloaliphatic and aliphatic dicarboxylic acids include malonic, glutaric, adipic, pimelic, azelaic, sebasic, fumaric, 2,2-dimethyl glutaric, suberic, 1,3-cyclopentanedicarboxylic, 1,4-cyclohexadicarboxylic, 1,3 -cyclohexanedicarboxylic, diglycolic, itaconic, maleic, and 2, 5-norbornanedicarboxylic. The polymerization is catalyzed by a catalyst, such as a titanium based catalyst (for example, tetrasopropylitanate, tetraisopropyl titanium, dibutoxydiatoacetoxy titanium, or tetrabutylitanate).

If desired, a diisocyanate chain diluent can be reactivated with the aliphatic polyester prepolymer to increase its molecular weight. The diisocyanates representative which include toluene 2,4-diisocyanates, toluene 2,6-diisocyanate, 2,4'-diphenylmethane diisocyanate, naphthylene-1,5-diisocyanate, xylylene diisocyanate, hexamethylene diisocyanate ("HMDI"), diisocyanate isophorone and methylenebis (2-isocyanatocyclohexane). The trifunctional isocyanate compounds can also be employed which contain isocyanurate and / or biurea groups with functionality of not less than three, or to replace the diisocyanate compounds partially with tri- or polyisocyanates. The preferred diisocyanate is hexamethylene diisocyanate. The amount of chain extender used is typically from about 0.3 to about 3.5% by weight, in some embodiments, from about 0.5 to about 2.5% by weight based on the percentage of the total weight of the polymer.

The aliphatic polyesters can be either a linear polymer or a long chain branched polymer. The long-chain branched polymers are generally prepared by using a lower molecular weight branched agent, such as a polyol, a polycarboxylic acid, a hydroxide acid, and so forth. Representative lower molecular weight polyols that can be employed as branched agents include glycerol, trimethylolpropane, trimethylolethane, polyetherols, glycerol, 1,2,4-butanetriol, pentaerythritol, 1,2,6-hexanetriol, sorbitol, cyclohexane 1, 1, 4, 4 -tetrakis (hydroxymethyl), isocyanurate tris (2-hydroxyethyl), and dipentaerythritol. Representative higher molecular weight polyols (molecular weight of 400 to 3,000) which can be used as branched agents include the triols by condensing alkylene oxides having 2 to 3 carbons, such as ethylene oxide and propylene oxide with initiators of polyol. Representative polycarboxylic acids which can be used as branching agents include hemimellitic acid, trimellitic acid (1, 2, -benzenetricarboxylic acid) and anhydride, trimesic acid (1, 3, 5-benzenetricarboxylic acid), pyromellitic acid and anhydride, benzenetetracarboxylic acid, benzophenone tetracarboxylic acid, 1,2, 2-ethane-tetracarboxylic acid, 1,2-etanetricarboxylic acid, 1,3-pentanetricarboxylic acid, and 1,2-acid , 3,4-cyclopentanetetracarboxylic. Representative hydroxy acids that can be used as branching agents include malic acid, citric acid, tartaric acid, 3-hydroxyglutaric acid, mucic acid, trihydroxyglutaric acid, 4-carboxythalic anhydride, hydroxyisophthalic acid, and 4- (beta-hydroxyethyl) acid. Such hydroxy acids contain a combination of 3 or more carboxyl and hydroxyl groups. Especially preferred branching agents include trimellitic acid, trimesic acid, pentaerythritol, trimethylol propane and 1,4-butanetriol.

Polycaprolactone polymers can also be used in the present invention. The polycaprolactone polymers are generally prepared by the polymerization of e-caprolactone, which is a seven-membered ring compound that is characterized by its reactivity. The splitting usually takes place in the carbonyl group. The higher molecular weight polycaprolactone can be prepared under the influence of a wide variety of catalysts, such as aluminum alkyls, organometallic compositions, such as metal alkyl groups IA, IIA, IIB, or IIIA, Grignard reagents , metal dialkyl Group II, calcium and other metal amides or alkyl amides, reaction products of alkaline earth hexamoniates, alkali oxides and acetonitrile, aluminum trialkoxides, alkaline earth aluminum or hydrides boron, alkali earth or alkali metal hydrides or alkali metals alone. An initiator can also be used in the preparation of the polycaprolactone, such as an aliphatic diol which forms a final terminal group. Examples of polycaprolactone polymers that may be suitable for use in the present invention include a variety of polycaprolactone polymers available from Union Carbide Corporation, Somerset, New Jersey, under the designation polycaprolactone polymers TONE ™ Polymer P767E and TONE ™ Polymer P787 .

The above-described lower-melting aliphatic polyesters described above are mainly aliphatic in nature, for example, the monomer constituents are mainly aliphatic, to optimize biodegradability. For example, lower melting point aliphatic polyesters typically contain at least about 50 mol%. In some embodiments, at least about 60 mol%, and in some embodiments, at least about 70 mol% of aliphatic monomer (s). Although primarily aliphatic in nature, the lower melting point polyesters may however contain a minor part of other monomer constituents, such as aromatic monomers (eg, terephthalic acid) which additionally improves the strength and toughness of the fibers . When used, the aromatic monomers may, for example, constitute from about 1 mol% to about 50 mol%, in some incorporations from about 10 mol% to about 40 mol% and in some embodiments, from about 15 mol. % mol up to about 30% mol of the lower cast point aliphatic polyester. In a particular example an aliphatic polyester containing a constituent of aromatic terephthalic acid monomer (~ 22 mol%) is available under the designation Ecoflex ™ F BX 7011 from Basf Corp. Another example of an aliphatic polyester containing a monomer of aromatic terephthalic acid (~ 25% mol) is available under the designation Enpol ™ 8060M from IRÉ Chemicals (South Korea).

Despite their particular type, the present inventors have found that "lower melting point" aliphatic polyesters having a certain combination of mechanical and thermal properties can provide improved strength and processability to the multi-component fibers resulting. For example, aliphatic polyesters having a much higher molecular weight generally possess entangled polymer chains and therefore result in a thermoplastic composition that is very difficult to process. Conversely, polyesters having a much lower molecular weight generally do not possess sufficient entanglement, which leads to a relatively weak casting strength. Therefore, the "lower melting point" aliphatic polyesters employed in the present invention typically have a number average molecular weight ("Mn") in the range from about 30,000 to about 120,000 Daltons, in some embodiments from about from 40,000 to around 100,000 Daltons, and in some additions, from around 45,000 to around 85,000 Daltons. In the same way, the "lower melting point" aliphatic polyesters also typically have a weight average molecular weight ("Mw") in the range from about 30,000 to about 240,000 Daltons, in some incorporations from about 50,000. up to around 190,000 Daltons, and in some additions, from around 60,000 to around 105,000 Daltons. The molecular weight distribution of the selected polymers is also relatively narrow to improve polymer processing and provide more consistent properties. That is, the ratio of average molecular weight weight to average molecular weight number ("Mw / Mn"), for example, the "Polydispersity Index", is relatively lower. For example, the Polydispersity Index is typically in the range of about 1.0 to about 3.0, in some incorporations from about 1.2 to about 2.0, and in some additions, from about 1.4 to about 1.8. The weight and number of average molecular weights can be determined by methods known to those skilled in the art.

To provide improved processability, the "lower melting point" aliphatic polyester is also selected to have an apparent viscosity with a certain range. More specifically, aliphatic polyesters having a greater than an apparent viscosity may generally be difficult to process. On the other hand, aliphatic polyesters having a much lower apparent viscosity will generally result in an extruded fiber that lacks tensile strength and sufficient bonding capacity. Therefore, in most of the incorporations, the "Lower melting point" aliphatic polyester has an apparent viscosity of from about 50 to about 215 Pascal seconds (Pa's), in some incorporations from about 75 to about 200 Pascal seconds, and in some embodiments, from about 80 to about 150 Pascal seconds, as determined at a temperature of 160 ° C and a cut rate of 1000 sec. "The present inventors have discovered that the particular combination of molecular weight and viscosity previously disclosed results in polymers that they have improved processability without adversely affecting the strength and bonding capacity of the resulting fiber.

The melt flow rate of the "lower melting point" aliphatic polyesters can also be selected with a certain range to optimize the properties of the resulting fibers. The melt flow rate is the weight of a polymer (in grams) that can be forced through an extrusion rheometer hole (0.0825 inches in diameter) when it is subjected to a force of 2160 grams in 10 minutes at 190 ° C. Generally speaking, the melt flow rate is sufficiently high to improve the melt processability, but not too high to adversely interfere with the binding properties of the fibers. Therefore, in most embodiments of the present invention, the "lower melting point" aliphatic polyesters have a melt flow rate of from about 5 to about 200 grams per 10 minutes, in some additions from about 15 to about 160 grams per 10 minutes, and in some additions, from about 20 to about 120 grams per 10 minutes, measured in accordance with Test Method ASTM D1238-E.

The crystallinity of the aliphatic polyester also influences the properties of the resulting multi-component fibers. That is, polymers that have a high degree of melting and heat content of crystallization are more easily incorporated into the woven products attached. For example, such polymers are more readily available to join at higher speeds and also have a lower degree of shrinkage, thereby improving fabric stability, tensile strength, and fabric aesthetics. Therefore, the aliphatic polyesters are typically selected to have a degree of crystallinity or latent heat to melt (? Hf) of greater than about 25 Joules per gram ("J / g"), in some higher intakes of about of 35 Joules per gram, and in some additions, higher than around 50 Joules per gram. In the same way, aliphatic polyesters are typically also selected to have a latent heat of crystallinity (? HC) of higher than about 35 Joules per gram ("J / g"), in some embodiments higher about 50 Joules per gram, and in some additions, higher than about 60 Joules per gram.

One difficulty encountered in the thermal processing of aliphatic polyester polymers in fibers is the sticky nature of these polymers. Attempts to pull the fibers, either mechanically, or through a process of pulling with air, can often result in the aggregation of the fibers into a solid mass. Therefore, in accordance with the present invention, the "lower melting point" aliphatic polyesters are also selected to have a relatively higher crystallization temperature ("Tc"), whereby stickyness is reduced. Specifically, the crystallization temperature may range from about 40CC to about 100 ° C, in some incorporations from about 50 ° C to about 90 ° C, and in some additions, from about 60 ° C to around 80 ° C. As will be discussed in more detail below, and the latent heat of fusion (? Hf), the latent heat of crystallization (? HC), and the crystallization temperature can all be determined using differential scanning calorimetry ("DSC") of in accordance with ASTM D-3417.

Any of a variety of "lower melting point" aliphatic polyester polymers can possess the previously referenced mechanical and thermal properties desired. In particular embodiments of the present invention, for example, polyethylene succinate copolyesters are employed as the second component of the multi-component fibers. A specific example of a polybutylene succinate polymer is commercially available from IRÉ Chemicals (South Korea) under the designation Enpol ™ G4500.

A beneficial aspect of the present invention is that the above-described mechanical and thermal properties of the "lower melting point" aliphatic polyesters can be provided without the need for conventional additives. For example, many conventional biodegradable thermoplastic compositions require the use of a nucleating agent to improve processing and to facilitate crystallization during immersion. One type of such nucleating agent is a multiple carboxylic acid, such as a succinic acid, glutaric acid, adipic acid, pimelic acid, suberic acid, azelaic acid, sec acid, and mixtures of such acids, such as they are described in U.S. Patent No. 6,177,193 issued to Tsai et al. The present inventors have discovered, however, that through the careful selection of an aliphatic polyester having certain physical and thermal properties, such nucleating agents are not necessarily required. In fact, the current inventors have discovered that excellent results can be achieved using aliphatic polyesters as the main ingredient of the second component. That is, the aliphatic polyesters can constitute at least about 90% by weight, in some embodiments at least about 92% by weight, and in some embodiments, at least about 95% by weight of the second component. However, it should be understood that nucleating agents can be used in some embodiments of the present invention. When used, however, nucleating agents are typically present in an amount of less than about 0.5% by weight, in some embodiments less than about 0.25% by weight, and in some embodiments, less than about 0.1% by weight. weight of the second component.

Although aliphatic polyesters are the main ingredient of the second component, other ingredients can of course be used as the second component for a variety of different reasons. For example, a wetting agent may be employed in some embodiments of the present invention to improve the hydrophilicity of the resulting fibers. Wetting agents suitable for use in the present invention are generally compatible with aliphatic polyesters. Examples of suitable wetting agents may include surfactants, such as the ethoxylated alcohols UNITHOX® 480 and UNITHOX® 750, or the amide acid ethoxylates.

UNICID ™, all available from Petrolite Corporation of Tulsa, O Lahoma. Other suitable wetting agents are described in U.S. Patent No. 6,177,193 issued to Tsai et al., Which is hereby incorporated by reference in its entirety for all relevant purposes. Still other materials that may be used include, without limitation, pigments, antioxidants, stabilizers, surfactants, waxes, flow promoters, solid solvents, plasticizers, particulates, and other aggregate materials to improve processability. of the thermoplastic composition. When used, it is usually desired that the amounts of these additional ingredients be minimized to ensure optimal compatibility and cost effectiveness. Therefore, for example, it is usually desired that such ingredients constitute less than about 10% by weight, in some embodiments less than about 8% by weight, and that in some embodiments, less than about 5% by weight of the second component.

III. Methods to Form Multiple Component Fibers Any of a variety of known techniques can be employed to form the multiple component fibers of the present invention. Typically, the components are extruded in separate extruders, but these can also be bonded together. Referring to figure 1, for example, an embodiment of a process 10 for forming multi-component fibers according to the present invention is shown. As illustrated, the process 10 of this incorporation is arranged to produce bicomponent fibers, although it should be understood that other embodiments are contemplated by the present invention. The process 10 employs a pair of extruders 12a and 12b to separately extrude a first component A (e.g., the "higher melting point" polymer component) and a second component B (e.g., the "point" polymer component). of superior cast iron "). The relative amount of components A and B can generally vary based on the desired properties. For example, the first component A can constitute from about 15% by weight to about 95% by weight, in some embodiments from about 10% by weight to about 90% by weight, and in some embodiments, from about 15% by weight up to about 85% by weight of the multi-component fibers. In the same way, the second component B can constitute from about 5% by weight to about 95% by weight, in some embodiments from about 10% by weight to about 90% by weight, and in some embodiments, from about 15% by weight up to about 85% by weight of the multi-component fibers.

The first component A is fed into the respective extruder 12a from a first hopper 14a and the second component B is fed into the respective extruder 12b from a second hopper 14b. Components A and B are fed from extruders 12a and 12b through respective polymer conduits 16a and 16b of a spinner member 18. Spinners for extruding multi-component fibers are well known to those skilled in the art. For example, the spinner member 18 may include a box containing a linking pack having a plurality of stacked plates on top of each other and having a pattern of apertures arranged to create flow paths for directing polymer components A and B separately through the spinner member 18. The spinner member 18 also has openings arranged in one or more rows. The openings form a curtain of extruded fibers downwardly when the polymers are extruded therethrough. The spinner member 18 may be arranged to form sheath / core, side by side, pie, or other configurations.

The process 10 also employs a submerged blower 20 positioned adjacent the fiber curtain extending from the spinner member 18. The air from the submerged air blower 20 immerses the fibers extending from the spinner member 18. The submerged air it can be directed from one side of the fiber curtain as shown in figure 1 or both sides of the fiber curtain. A vacuum cleaner or fiber pulling unit 22 is placed below the organ spinner 18 and receive the submerged fibers. Vacuum cleaners or fiber pulling units for use in melted bonded polymers are well known in the art. Fiber pulling units suitable for use in the process of the present invention include a linear fiber vacuum cleaner of the type shown in U.S. Patent Nos. 3,802,817 and 3,423,255, which are hereby incorporated in their entirety by reference to them for all relevant purposes. The fiber pulling unit 22 generally includes an elongated vertical path through which the fibers are pulled by sucking air that penetrates from the sides of the path and which flows downward through the path. A heater with blower 24 supplied with air sucking the fiber pulling unit 22. The suctioning air pulls the fibers and air from the environment through the fiber pulling unit 22. The fibers can then be wound into a godet roller assembly 42. Alternatively, the fibers can be directly formed into a coherent woven structure by randomly depositing the fibers on a forming surface (optionally with the aid of a vacuum) and then joining the resulting fabric using any known technique .

To initiate fiber formation, the hoppers 14a and 14b are initially filled with the respective components A and B. The components A and B are melted and extruded by the respective extruders 12a and 12b through polymer conduits 16a and 16b and spinner 18. Due to the relatively lower apparent viscosity of the aliphatic polyesters used in the present invention, lower extrusion temperatures may be employed. For example, extruder 12b for Component B ("lower melting point" polyester) may employ one or more multiple zones operating at a temperature of from about 120 ° C to about 200 ° C, and in some embodiments , from around 145 ° C to around 195 ° C. In the same manner, the extruder 12a for Component A ("higher melting point" polyester) may employ one or more multiple zones operating at a temperature of from about 160 ° C to about 250 ° C, and in some additions, from around 190 ° C to around 225 ° C. Cutoff rates typically range from about 100 seconds-1 to about 10,000 seconds-1, in some additions from about 500 seconds-1 to about 5,000 seconds-1, and in some additions, from about 800 seconds-1 to about 1,200 seconds-1.

While the extruded fibers extend below the spinner member 18, an air stream from the submerged blower 20 at least partially immerses the fibers. Such a process generally reduces the temperature of the extruded polymers by at least about 100 ° C over a relatively short time (seconds). This it can generally reduce the temperature change necessary for cooling, preferably to be less than 150 ° C and, in some cases, less than 100 ° C. The ability to use the relatively lower extruder temperature in the present invention also allows for the use of lower submerging temperatures. For example, the submerged blower 20 may employ one or more zones operating at a temperature of from about 20 ° C to about 100 ° C., and in some additions, from around 25 ° C to around 60 ° C. After submerging, the fibers are pulled in the vertical path of the fiber pull unit 22 by a flow of gas such as air, heater or blower 24 through the fiber pull unit. The loose gas causes the fibers to be pulled or attenuated which increases the molecular orientation or the crystallinity of the polymers that form the fibers. The fibers are deposited through an outlet opening of the fiber pulling unit 22 and in a godet roller assembly 42. Due to the high strength of the fibers of the present invention, the higher pulling ratios (e.g. godet roller speed 42 divided by the cast pump rate of the extruders 12a and 12b) can be achieved in the present invention. For example, the pull rate can be from about 200: 1 to about 6000: 1, in some additions from about 500: 1 to about 5,000: 1, and in some additions, from about 1000: 1 to around 4000: 1. Alternatively, the fibers can be directly deposited on a perforated surface (not shown) to directly form a non-woven fabric.

If desired, the fibers collected in the godet roll 42 can optionally be subjected to further on-line processing and / or conversion steps (not shown) as will be understood by those skilled in the art. For example, the basic fibers can be formed by "cold-pulling" the fibers collected at a temperature below their temperature of softness to the desired diameter, and then the pleating, texturing, and / or cutting of the fibers to the desired fiber length. The desired fiber length and denier of the fibers may vary depending on the desired application. Typically, the fibers are formed to have an average fiber length in the range of from about 3 to about 80 millimeters, in some incorporations from about 4 to about 65 millimeters, and in some incorporations, from about 5 to around 50 millimeters. The denier by filament of fibers also by desire less than about 6, in some incorporations less than about 3, and in some additions, from about 0.5 to about 3. In addition, the fibers are generally "microfibers", for example, small diameter fibers that have an average diameter of no more than about 100 microns, in some incorporations from about 0.5 microns to about of 50 microns, and in some additions, from around 4 microns to around 40 microns.

Various other methods for forming multi-component fibers can also be used in the present invention, as described in U.S. Patent No. 4,789,592 issued to Taniguchi et al. And U.S. Patent Nos. 5,336,552. granted to Strack and others; 5,108,820 granted to Kaneko and others; 4,795,668 granted to Kruege and others; 5,382,400 granted to Pike and others; 5,336,552 granted to Strack and others, and 6,200,669 granted to Marmon and others, which are hereby incorporated in their entirety by reference to them for all purposes. Fibers of multiple components that have various irregular shapes can also be formed, as described in U.S. Patent Nos. 5,277,976 to Hogle et al .; 5,162,074 awarded to Hills; 5,466,410 awarded to Hills; 5,069,970 issued to Largman and others; and 5,057,368 to Largman and others, which are hereby incorporated by reference in their entirety for all purposes.

Despite the particular manner in which they are formed, the present inventors have discovered that the resulting multi-component fibers exhibit excellent strength characteristics. A parameter that is indicative of the relative strength of the multi-component fibers of the present invention is the "tenacity", which indicates the tensile strength of a fiber expressed as the unit linear force or density. For example, the multi-component fibers of the present invention can have a toughness of from about 0.75 to about 7.0 grams of force ("gf") per denier, in some embodiments from about 1.0 to about 5.0 grams of force by denier, and that in some additions, from around 1.5 to about 4.0 grams of force per denier. Additionally, the multi-component fibers of the present invention also have a relatively higher "voltage at peak voltage", which indicates the voltage at the maximum voltage expressed in force per unit area. For example, the multi-component fibers of the present invention may have a voltage at the peak voltage of from about 100 to about 600 Megapascals (MPa), in some incorporations from about 150 to about 500 Megapascals, and in some incorporations, from around 200 to around 400 Megapascals.

IV. Non-woven fabrics The multi-component fibers of the present invention can be used in any type of non-woven fabric, such as a meltblown fabric, a spunbonded fabric, a bonded woven fabric, a stretched fabric wet, a fabric stretched with air, a coform fabric, a hydraulically entangled fabric, and so on. In one embodiment, for example, the fibers are formed into a carded fabric by placing bundles of fibers in a picker that stops the fibers. Then, the fibers are sent through a carding or combing unit which additionally breaks apart and aligns the fibers in the machine direction so as to form a fibrous nonwoven fabric oriented in the machine direction. Once formed, the non-woven fabric is typically stabilized by one or more joining techniques. For example, a continuous air dryer containing one or more heating zones may be employed which heats the air to a temperature higher than the melting temperature of the second component (eg, sheath) of the multi-component fibers, but less of the melting temperature of the first component (for example, core). This hot air passes through the non-woven fabric, so I founded the second component and forms the interfiber joints to thermally stabilize the fabric. When polylactic acid and polybutylene succinate are used as polymer components, for example, air flowing through the continuous air union can have a temperature in the range of about 100 ° C to about 180 ° C. The waiting time in the continuous air unit can also be around 120 seconds or less. It should be understood, however, that the parameters of the continuous air depends on factors such as the type of polymers used and the thickness of the fabric.

Ultrasonic bonding techniques can also be used employing a rotating or stationary horn and an anvil roller with woven pattern. Such techniques are described in U.S. Patent Nos. 3,939,033 to Grgach et al .; 3,844,869 granted to Rust Jr .; the 4,259,399 granted to Hill; 5,096,532 issued to Neuwirth and others; 5,110,403 granted to Ehlet, and 5,817,199 granted to Brennecke and others, which are incorporated herein in their entirety by repellency the same for all purposes.

Alternatively the non-woven fabric can be thermally knitted to provide a fabric having numerous discrete and small bonding points. This process generally involves passing the fabric between two heated rollers, such as an engraved pattern roller and a second bonding roller. The engraved roll has a pattern in some way such that the fabric is not bonded over its entire surface, and the second roll can be smooth or patterned. Several patterns for engraved rolls have been developed for functional and / or aesthetic reasons. Exemplary binding patterns include but are not limited to those described in U.S. Patent Nos. 3,855,046 issued to Hansen et al., 5,620,779 issued to Levy et al .; ,962,112 issued to Haynes and others; and 6,093665 granted to Sayovitz et al., United States of America Design Patents 428267 granted to Romano et al. and 390, 708 granted to Brown, which are hereby incorporated in their entirety with reference thereto for all purposes.; for example, the non-woven fabric can be bonded to have a total bond area of less than about 30% and a higher uniform bond density of about 100 bonds per square inch, and preferably from about 2 to about 30% (as determined by conventional optical microscopic methods) and a bond density of from about 250 to about 500 bolt joints per square inch. Such a combination of total bonded area and bond density can be achieved by joining the fabric with a pin bonding pattern having more than about 100 bolt joints per square inch which provides a total bonding surface area of less than about 30% when contact is made with the smooth anvil roller. In some additions, the joint pattern can have a bolt-joint density of from about 250 to about 350 bolt joints per square inch and a surface area of a total of from about 10% to about 25% when made contact with a smooth anvil roller.

The multicomponent fibers can constitute the complete fibrous component of the nonwoven fabric or mixed with other types of fibers. When they are mixed with other types of fibers, it is normally desired that the multi-component fibers of the present invention constitute from about 0.5 to about 60% by weight, in some embodiments from about 1% by weight to about 40% by weight, and in some embodiments, from about 2% by weight to about 20% by weight of the total amount of fibers employed in the non-woven fabric.

For example, the multi-component multicomponent fibers of the present invention can be blended with the pulp fibers, such as a pulp of average high fiber length, a pulp of low average length or mixtures thereof. An example of high average length fluff pulp fibers include soft wood kraft pulp fibers. Soft wood kraft pulp fibers are derived from coniferous trees and include pulp fibers such as, but are not limited to, softwood species from the North, the West and the South, including redwood, red cedar, spruce (hemlock). ), Douglas fir, true fir, pine (for example southern pines), spruce, (for example black spruce, combinations thereof, etc.) Northern softwood kraft pulp fibers can be used in the present invention. example of southern softwood kraft pulp fibers suitable for use in the present invention include those available from the Weyerhaeuser company with offices in Federal Way, Washington under the trade designation "NB-416." Another pulp suitable for use in the present invention is a bleached sulphate soft wood pulp containing primarily softwood fibers is available from Bowater Corporation with offices in Greenville, South Carolina under the trade name CoosAbsorb Pulp S. Low average length fibers can also be used in the present invention. An example of the pulp fibers of suitable low average length is the fibers of hardwood kraft pulps. Hardwood kraft pulp fibers are derived from deciduous trees and include pulp fibers such as, but not limited to eucalyptus, maple, birch, poplar, trembling, etc. Eucalyptus kraft pulp fibers can be particularly desired to increase softness, improve brilliance, increase opacity and change the pore structure of the sheet to increase its transmission capacity. Typically, the pulp fibers constitute from about 30% by weight to about 95% by weight, in some embodiments from about 40% by weight to about 90% by weight, and in some embodiments from about 50% by weight to about 85% by weight of the non-woven fabric.

The additional monocomponent and / or multiple component synthetic fibers can also be used in the nonwoven fabric. Some suitable polymers that can be used to form the synthetic fibers include, but are not limited to: polyolefins, for example polyethylene, polypropylene, polybutylene and the like; polytetrafluoroethylene, polyesters for example polyethylene terephthalate and the like; polyvinyl acetate, polyvinyl chlorine acetate, polyvinyl butyral, acrylic resins, for example polyacrylate, polymethacrylate, polymethylmethacrylate, and the like; polyamides, for example nylon; polyvinyl chloride; polyvinylidene chloride; polystyrene; polyvinyl alcohol; polyurethanes; polylactic acid and the like. If desired, biodegradable polymers, such as poly (glycolic acid) (PGA), poly (lactic acid) (PLA), poly (β-malic acid) (PMLA), poly (e-caprolatone) (PCL), poly (p-dioxanone) (PDS), and poly (3-hydroxybutyrate) (PHB). Some examples of the known synthetic fibers include the bicomponent sheath-core fibers available from KoSa Inc., Charlotte, North Carolina under the designations T-255 and T-256, both of which use a polyolefin sheath or T- 254 which has a low melted copolyester sheath. Still other known bicomponent fibers that can be used include those available from Chisso Corporaton of Moriyama, Japan or Fibervision LLC of Wilmington, Delaware.

Synthetic or natural cellulosic polymers may also be used, including but not limited to cellulose esters, cellulose ethers; cellulose nitrates; cellulose acetates; cellulose acetate butyrates; ethyl cellulose; regenerated celluloses, such as viscose rayon and others. Non-woody fibers can also be used, including the native fiber of hemp, straw, flax, bagasse and mixtures thereof can be used in the present invention.

In addition, super absorbent materials may also be contained within the nonwoven fabric; Super absorbent materials are materials that can swell in water capable of absorbing at least about 20 times their weight and in some cases at least about 30 times their weight in aqueous solution containing 0.9% by weight of sodium chloride. The super absorbent materials can be polymers and natural, synthetic and modified natural materials. Examples of the synthetic super absorbent polymers include the alkali metal and ammonium salts of poly (acrylic acid) and poly (methacrylic acid), poly (archylamides), poly (vinyl ethers), maleic anhydride copolymers with vinyl ethers and alpha olefins, poly (vinyl pyrrolidone), poly (vinyl morpholinone), poly (vinyl alcohol) and mixtures and copolymers thereof. Other super absorbent materials include natural and modified natural polymers, such as hydrolyzed acrylonitrile grafted starch, acid grafted starch, methyl cellulose, chitosan, carboxymethyl cellulose, hydroxypropyl cellulose, and natural gums, such as alginates, xanthan, locust bean gum and others. Mixtures of natural and fully or partially synthetic super absorbent polymers may also be useful in the present invention. Polymers are particularly suitable absorbers such as YSORB 8800AD (BASF of Charlotte, North Carolina and FAVOR SXM 9300 (available from Degusta Superabsorber of Greensboro, NC) When the super absorbent material was used it can range from about 30% by weight to about 95 % by weight, in some incorporations of from about 40% by weight to about 90% by weight and in some incorporations from about 50% to about 85% by weight of the non-woven fabric V. Absorbent Articles Non-woven fabrics as described above, may be used in an absorbent article, such as, but not limited to absorbent articles for personal care such as diapers, underpants, absorbent undergarments, incontinence articles, sanitary napkins , swimwear, baby wipes and others; medical absorbent articles such as garments, windowing materials, interior pads, bed pads, bandages, absorbent covers, and medical wipes; cleaning cloths for food service; articles of clothing; and others. Suitable materials and processes for forming such absorbent articles are well known to those skilled in the art. Typically, the absorbent articles include a layer essentially impermeable to liquid (e.g. the outer cover), a liquid permeable layer (e.g., a side-to-body liner, an emergence layer, etc.), and an absorbent core. The nonwoven fabric of the present invention can be used as one or more of the liquid permeable, liquid impervious and / or absorbent layers.

Various embodiments of the absorbent article that can be formed according to the present invention will now be described in greater detail. For purposes of illustration only, an absorbent article is shown in Figure 5 as the diaper 101. However as noted above the invention may be involved in other types of absorbent articles, such as incontinence articles., sanitary napkins, underpants, feminine pads, children's underpants and others. In the illustrated embodiment diaper 101 shown having an hourglass shape in a non-clamped configuration, however other shapes may of course be used, such as the generally rectangular shape, the T-shape, or the I-shape. shown, the diaper 101 includes a frame 102 formed by several components, including an outer cover 117, a body-side liner 105, an absorbent core 103 and an emergence layer 107. It should be understood, however, that other layers may also to be used in the present invention. In a similar manner one or more of the layers mentioned in figure 5 can be eliminated in certain embodiments of the present invention.

The outer cover 117 is typically formed of a material that is essentially impermeable to liquids. For example, the outer cover 117 may be formed of a thin plastic film or other material impermeable to the flexible liquid. In one embodiment the outer cover 117 is formed of a polyethylene film having a thickness of about 0.01 millimeters about 0.05 millimeters. The film may be impermeable to liquids, but permeable to gases and water vapor (for example having the ability to breathe). This allows the vapors to escape from the absorbent core 103, but still prevents the exuded liquids from passing through the outer cover 117. If a more cloth-like feel is desired, the outer cover 117 may be formed of a film. of polyolefin laminated to the non-woven fabric. For example, a thinned-stretched polypropylene film having a thickness of from about 0.015 millimeters can be thermally laminated to a woven fabric bonded with polypropylene fiber yarn. If desired, the non-woven fabric may contain the multi-component fibers of the present invention.

Diaper 101 also includes a side-to-body lining 105. Body-side lining 105 is generally employed to help isolate the skin of the wearer from the body. liquids maintained in the absorbent core 103. For example, the body facing liner 105 which is typically docile to feel soft and non-irritating to the wearer's skin. Typically the liner 105 is also less hydrophilic than the absorbent core 103 so that its surface remains relatively close to the wearer. The liner 105 may be permeable to liquid to allow the liquid to easily penetrate through its thickness. In a particular embodiment, the liner includes a non-woven fabric such as a fabric knitted together as a meltblown fabric, or a fabric containing the multi-component fibers of the present invention. Exemplary liner constructions containing a non-woven fabric are described in U.S. Patent Nos. 5,192,606; 5,702,377; 5,931,823; 6,060,638; and 6,150,002, as well as in the patent applications of the United States of America Publications Nos. 2004/0102750, 2005/0054255 and 2005/0059941, all of which are hereby incorporated by reference in their entirety for all purposes.

As illustrated in Figure 5, the diaper 101 may also include an emergence layer 107 that helps decelerate and diffuse liquid surges or sprouts that can be easily introduced into the absorbent core 103. Desirably, the emergence layer 107 quickly accepts and temporarily holds the liquid before releasing it inside the holding storage parts of the absorbent core 103. In the illustrated embodiment, for example, the emergence layer 107 is interposed between an inward facing surface 116 of the side-to-body lining 105 and the absorbent core 103. Alternatively, the emergence layer 107 may be located on an outward facing surface 118 of the side-to-body lining 105. The emergence layer 107 is typically constructed of materials highly permeable to liquid. Suitable materials may include pore-knitted materials, porous non-woven materials and perforated films. In a particular embodiment, the emergence layer 107 includes a non-woven fabric containing the multi-component fibers of the present invention. Other examples of suitable emergence layers are described in U.S. Patent Nos. 5,486,166 issued to Ellis and others and 5,490,846 issued to Ellis and others which are hereby incorporated by reference in their entirety for all purposes.

In addition to the aforementioned components, the diaper 101 may also contain various other components as is known in the art. For example, the diaper 101 may also contain an essentially hydrophilic tissue wrapping sheet (not shown) that helps maintain the integrity of the fibrous structure of the absorbent core 103. The tissue wrapping sheet is typically placed around the absorbent core 103 over at least the two face surfaces of the same, and is composed of an absorbent cellulosic material such as a crepe or a wet high-strength tissue. The corresponding tissue wrap can be configured to provide a transmission layer which helps to rapidly distribute the liquid over the mass of absorbent fibers of the absorbent core 103. The wrap sheet material on one side of the absorbent fibrous mass can be attached to the wrapping sheet located on the opposite side of the fibrous mass to effectively trap the absorbent core 103. If desired, the wrapping sheet can be formed of a woven fabric including the multi-component fibers of the present invention.

In addition, the diaper 101 may also include a ventilation layer (not shown) that is placed between the absorbent core 103 and the outer cover 117. When used, the ventilation layer may assist in insulating the outer cover 117 of the absorbent core 103 , thereby reducing wetness in the outer cover 117. Examples of the ventilation layers may include the nonwoven fabric laminated to a breathable film as described in United States of America Patent No. 6, 663, 611 granted to Blaney and others which is incorporated herein in its entirety by reference for all purposes. Such non-woven fabrics can be formed from a non-woven fabric woven that includes the multi-component fibers of the present invention.

In some embodiments, the diaper 101 may also include a pair of ears (not shown) extending from the lateral edges 132 of the diaper 101 within the waist regions. The ears can be formed integrally with a selected diaper component. For example, the ears can be formed integrally with the outer cover 117 or the material used to provide the upper surfaces. In the alternate configurations, the ears may be provided by the connected members assembled to the outer cover 117, the upper surface, between the outer cover 117 and the top surface or in various other configurations.

As representatively illustrated in Figure 5, the diaper 101 may also include a pair of containment fins 112 that are configured to provide a barrier and to contain the lateral flow of exudates from the body. The containment fins 112 can be located along the edges of the laterally opposite side 132 of the side-to-body liner 105 on one side of the side edges of the absorbent core 103. The containment fins 112 can extend longitudinally along the length of the body. The entire length of the absorbent core 103 or may only extend partially along the length of the absorbent core 103. When the containment fins 112 are shorter in length than absorbent core 103, these can be selectively placed anywhere along side edges 132 of diaper 101 in crotch region 110. In one embodiment, containment fins 112 they extend along the entire length of the absorbent core 103 to better contain the body exudates. Such containment fins 112 are generally well known to those skilled in the art. For example, suitable constructions and arrangements for containment fins 112 are described in United States of America 4,704,116 issued to Enloe, which is hereby incorporated by reference in its entirety for all purposes.

The diaper 101 may include various elastic or stretchable materials, such as a pair of elastic leg members 106 fixed to the side edges 132 to further prevent runoff of exudates from the body and to support the absorbent core 103. In addition a pair of members waist elastics 108 can be attached to the opposite longitudinal waist edges 115 of the diaper 101. The elastic leg members 106 and the waist elastic members 108 are generally adapted to closely fit around the user's legs and waist in use to maintain a positive contact relationship with the user and to effectively reduce or eliminate the filtering of body exudates from the diaper 101. As used Here, the terms "elastic" "stretched" include any material that can be stretched and returned to its original shape when relaxed. Polymers suitable for forming such materials include but are not limited to block copolymers of polystyrene, polyisoprene and polybutadiene; copolymers of ethylene, natural rubbers and urethanes; etc. Particularly suitable are styrene-butadiene block copolymers sold by Kraton Polymers of Houston, Texas, under the trade name Kraton®. Other suitable polymers include ethylene copolymers, including without limitation, ethylene vinyl acetate, ethylene methyl acrylate, ethylene ethyl acrylate, ethylene acrylic acid, stretchable ethylene-propylene copolymers and combinations thereof. Also suitable are the compounds extruded together from the above, and the integrated elastomeric compounds wherein the short fibers of polypropylene, polyester, cotton and other materials are integrated into a blown fabric with elastomeric melt. Certain elastomeric metallocene or single site catalyzed olefin copolymers and copolymers are also suitable for these panels.

The diaper 101 may also include one or more fasteners 130. For example, two flexible fasteners 130 are illustrated in Figure 5 on the opposite side edges of the waist regions to create a waist opening and a pair of leg openings around the waist. user. The shape of the fasteners 130 may generally vary, but it may include, for example, generally rectangular shapes, square shapes, circular shapes, triangular shapes, oval shapes, linear shapes and others. The fasteners may include, for example, a hook material. In a particular embodiment, each fastener 130 includes a separate piece of hook material fixed to the inner surface of a flexible backing.

The various regions and / or components of the diaper 101 can be assembled together using any known attachment mechanism, such as adhesive, ultrasonic, thermal bonding, etc. Suitable adhesives may include, for example, hot melt adhesives, pressure sensitive adhesives and others. When used, the adhesive can be applied as a uniform layer, a patterned layer, a spray pattern or any separate lines, swirls or dots. In the illustrated embodiment, for example, the outer cover 117 and the side-to-body liner 105 are assembled to each other and to the absorbent core 103 using an adhesive. Alternatively, the absorbent core 103 may be connected to the outer cover 117 using conventional fasteners, such as buttons, hook-and-loop type fasteners, adhesive tape fasteners and others. Similarly, other diaper components, such as the elastic leg members 106, the waist elastic members 108 and the fasteners 130 also they can be assembled in the diaper 101 using any fastening mechanism.

While various configurations of a diaper have been described above, it should be understood that other configurations of absorbent article and diaper are also included within the scope of the present invention. In addition, the present invention is by no means limited to diapers. In fact, any other absorbent article can be formed in accordance with the present invention, including, but not limited to absorbent articles for personal care such as underpants, absorbent underpants, adult incontinence products, products for women's hygiene (for example, sanitary napkins), swimming clothes, baby wipes and others; medical absorbent articles, such as garments, windowing materials, inner pads, bandages, absorbent covers and medical cleansing wipes; cleaning cloths for food service; articles of clothing and others. Several examples of such absorbent articles are described in U.S. Patent Nos. 5,649,916 issued to DiPalma et al .; 6,110,158 granted to Kielpikowski; 6,663,611 granted to Blaney and others, which are incorporated herein in their entirety for all purposes. Still other suitable articles are described in the patent application of the United States of America publication number 2004/0060112 Al a Fell et al., as well as in the United States of America patents number 4,886,512 granted to Damico and others; 5,558,659 issued to Sherrod and others; 6,888,044 granted to Fell and others; and 6,511,465 issued to Freiburger and others, all of which are hereby incorporated by reference in their entirety for all purposes.

The present invention can also be better understood with reference to the following examples.

Test Methods Molecular weight : The molecular weight distribution of a polymer was determined by gel permeation chromatography ("GPC"). The samples were initially prepared by adding 0.5% by weight / v of the sample polymers in chloroform to 40 milliliter glass containers. For example, 0.05 ± 0.0005 grams of the polymer were added to 10 milliliters of chloroform. The prepared samples were placed on an orbital shaker and shaken overnight. The dissolved sample was filtered through a 0.45 micron PTFE membrane and analyzed using the following conditions: Columns Styragel HR 1,2,3,4 & 5E (5 in series) at 41 ° C Solvent / Eluent: Chloroform @ 1.0 milliliters per minute HPLC: Controller and gradient pump of 600E Waters, Waters 717 sampler Detector: Waters 2414 differential refractive detector at sensitivity = 30, at 40 ° C and scale factor of 20 Sample Concentration 0.5% polymer "as is" Injection volume: 50 microliters Standard calibration: Polystyrene narrow molecular weight, 30-microliter volume injected.

The number average molecular weight (MWn), the weight average molecular weight (MWW) and a first viscosity average molecular weight moment (MWZ) were obtained.

Apparent viscosity: The rheology properties of the polymer samples were determined using a Góttfert Rheograph 2003 capillary rheometer with WinRHEO analysis software version 2.31. The placement included a pressure transducer of 2000 bars and a round hole capillary matrix of 30/1: 0/180. The sample load was made by alternating between the sample addition and the packing with a rod. A melting time of 2 minutes preceded each test to allow the polymer to melt completely at the test temperature (usually 160 to 220 ° C). The rheometer capillary determined the apparent viscosity (Pa-s) at seven different cutting rates: 50, 100, 200, 500, 1000, 2000 and 5000 s-1. The rheology curve resulting from the apparent cutoff rate against the apparent viscosity gave an indication of how the polymer would run at the temperature in an extrusion process.

Melt Flow Index: The melt flow rate is the weight of the polymer (in grams) forced through an extrusion rheometer hole (0.0825 inches in diameter) when subjected to a force of 2160 grams in 10 minutes at 190 ° C. The melt flow rate was measured according to the ASTM D1238-E test method.

Thermal Properties: (melted point, Tg, and% crystallinity): The melting temperature, the glass transition temperature and the degree of crystallinity of a material were determined by differential scanning calorimetry (DSC). The differential scanning calorimetry was a THERMAL ANALYST 2910 differential scanning calorimeter which was equipped with a liquid nitrogen cooling accessory and a THERMAL ANALYST 2200 analysis software program (version 8.10), both of which are available from T.A. Instruments Inc., of New Castle, Delaware. To avoid direct handling of the samples, tweezers or other tools were used. Samples were placed on an aluminum tray and weighed to an accuracy of 0.01 milligrams on an analytical balance. A lid was placed on the sample of material on the tray. Typically, the resin pellets were placed directly on the weighing pan, and the fibers were cut to accommodate placement on the weighing pan and covering with the cap.

The differential scanning calorimeter was calibrated using an Indian metal standard and a baseline correction was carried out, as described in the operation manual for the differential scanning calorimeter. A sample of material was placed in the test chamber of the differential scanning calorimeter to test, and an empty tray was used as a reference. All tests were run with a nitrogen purge of 55 cubic centimeters per minute (industrial class) on the test chamber. For the resin pellet samples, the heating and cooling program was a two cycle test that started with a chamber equilibrium at -25 ° C, followed by a first heating period at a 10 ° heating rate C per minute at a temperature of 200 ° C, followed by equilibrium of the sample at 200CC for 3 minutes, followed by a first cooling period at a cooling rate of ° C per minute at a temperature of -25 ° C, followed by the balance of the sample at -25 ° C for 3 minutes and then a second heating period at a heating rate of 10 ° C per minute at a temperature of 200 ° C. For the fiber samples, the heating and cooling program went to a 1-cycle test that started with a chamber equilibrium at -25 ° C, followed by a heating period at a heating rate of 20 ° C per minute at a temperature of 200 ° C, followed by equilibrium of the sample at 200 ° C for 3 minutes, and then a cooling period at a cooling rate of 10 ° C per minute at a temperature of -25 ° C . All tests were run with a nitrogen purge of 55 cubic centimeters per minute (industrial class) on the test chamber.

The results were then evaluated using the THERMAL ANALYST 2200 analysis software program, which identified and rated the transition temperature of the glass (Tg) of inflection, the endothermic and exothermic peaks, and the areas under the peaks of the DSC schemes. . The transition temperature of the glass was identified as the region on the drawing line where a different change in inclination occurred, and the melting temperature was determined using an automatic inflection calculation. The areas under the peaks on the DSC schemes were determined in terms of joules per gram of sample (J / g). For example, the heated endothermic melting of a resin or sample fiber was determined by integrating the area of the endothermic peak. The area values were determined by converting the areas under the DSC schemes (for example the area of the endotherm) into units of joules per gram (J / g) using computer software. The percentage of crystallinity was calculated as follows: % of mortality = 100 * (A - B) / C where, A is the sum of endothermic peak areas (J / g); B is the sum of exothermic peak areas (J / g) C is the endothermic heat of the melt value for the selected polymer wherein such polymer has 100% crystallinity (J / g). For polylactic acid, C is 93.7 J / g (Cooper-White, J.J and Mackay, M.E., Journal of Polymer Sciences, Polymer Physics Edition, page 1806, volume 37 (1999)). The areas under the exothermic peaks found in the DSC explore due to insufficient crystallinity were subtracted from the area under the endothermic peak to appropriately represent the degree of crystallinity.

Stress Properties: Strip tensile strength values were determined in substantial accordance with ASTM Standard D-5034. Specifically, a sample of non-woven fabric was cut or otherwise provided with size dimensions measuring 25 millimeters (width) x 127 millimeters (length). A constant-rate-of-extension type of voltage tester was employed. The tension test system was a MTS SYNERGY 200 voltage tester, which is available from MTS Systems Corporation of Eden Prairie, Michigan. The voltage tester was equipped with a TTSWORKS 4.08B software from MTS Corporation to support the test. An appropriate load cell was selected so that the tested value fell within the range of 10-90% of the full scale load. The sample was maintained between the handles having a front and rear face measuring 25.4 millimeters x 76 millimeters. The gripping faces were rubberized, and the longest dimension of the handle was perpendicular to the pulling direction. The grip pressure was pneumatically maintained at a pressure of 40 pounds per square inch. The stress test was set at a rate of 300 millimeters per minute with a measurement length of 76 millimeters and a break sensitivity of 40%.

Three samples were tested by applying the test load along the machine direction and Three samples were tested by applying the test load along the transverse direction. In addition to the tensile strength, the peak load, the peak stretch (for example the percentage of elongation at the peak load) and the peak energy were measured. The peak strip tension loads for each tested specimen were arithmetically averaged to determine the tensile strength in the machine direction or in the transverse direction.

Fiber tenacity: The individual fiber specimens were carefully extracted from an unbound part of the fiber fabric in a way that did not significantly pull the fibers. These fiber specimens were shortened (for example cut with scissors) to 38 millimeters in length, and placed separately on a black velvet cloth. 10 to 15 fiber specimens were collected in this manner. The fiber specimens were then mounted in an essentially straight condition on a rectangular paper frame having an external dimension of 51 millimeters by 51 millimeters and an internal dimension of 25 millimeters by 25 millimeters. The ends of each fiber specimen were operatively attached to the frame by careful scrubbing of the fiber ends on the sides of the frame with adhesive tape. Each fiber specimen was then measured with respect to its transverse fiber dimension, relatively shorter and using a conventional laboratory microscope, which had been calibrated and set to a 40X magnification. The cross fiber dimension was recorded as the diameter of the individual fiber specimen. The frame helped assemble the ends of the sample fiber specimens in the upper and lower lugs at a constant rate of extension of the tension tester in a manner that avoided excessive damage to the fiber specimens.

A constant extension rate of the voltage tester and an appropriate load cell were used for the test. The load cell was chosen (for example ION) so that the test value fell within 10-90% of the full scale load. The voltage tester (for example MTS SYNERGY 200) and the load cell were obtained from MTS Systems Corporation of Eden Prairie, Michigan. The fiber specimens in the frame assembly were then mounted between the handles of the tension tester so that the ends of the fibers were operatively held by the handles of the tension tester. Then, the sides of the paper frame that extended parallel to the fiber length were cut or otherwise separated so that the tension tester applied the test force only to the fibers. The fibers were then subjected to a pull test at a pull rate and grip rate at 12 inches per minute. The resulting data were analyzed using a software program TESTWORKS 4 of MTS Corporation with the following test placements: Tenacity values were expressed in terms of grams-force per denier.

EXAMPLE 1 Various physical properties of the following aliphatic polyesters were tested.

Pl: Polybutylene Succinate obtained from IRÉ Chemicals, of South Korea under the name EnPol ™ G4500 (Class CE272); P2: Polybutylene Succinate obtained from IRÉ Chemicals, of South Korea under the name EnPol ™ G4500 (Class 1DF241); P3: Polybutylene Succinate obtained from IRÉ Chemicals, from South Korea under the name EnPol ™ G4500 (Class 2DF242); P4: Polybutylene Succinate obtained from IRÉ Chemicals, of South Korea under the name EnPol ™ G4560J; P5: Polybutylene succinate obtained from IRÉ Chemicals, of South Korea under the name EnPol ™ G4500 (Class CE272 - High MFI); P6: Polybutylene Succinate obtained from IRÉ Chemicals, of South Korea under the name EnPol ™ G4500 (Class CE272 - Mid MFI); P7: Polybutylene succinate obtained from Showa, Japan under the name Bionolle ™ 1020; P8: Polybutylene succinate obtained from Showa, Japan under the name Bionolle ™ 1903; P9: Polybutylene succinate obtained from Showa, Japan under the name Bionolle ™ 1003; Y PÍO: Polylactic acid obtained from Biomer Inc., Germany under the name Biomer ™ L9000.

The results are set down in the tables 1 and 2.

Table 1: Melt Properties and Molecular Weight Table 2: Rheological Properties (30/1/180 Round Orifice) As indicated, the Bionolle ™ polymers (P7-P9) were very viscous compared to the EnPol ™ G4500 (P2-P4) polymers.

EXAMPLE 2 Several polybutylene succinate polymers were dried at 160 ° F and the polylactic acid polymer was dried at 175 ° F, both for at least 48 hours. The target moisture level was 50 parts per million. The polymers were then fed through the sealed hoppers in extruders that fed the melted polymer to the melt pump. The extruders were each single screw type and had five separately controlled heating zones. The melt pump was a positive displacement type pump whose production (cc / sec) was controlled through its speed (rpm). The extruder production was automatically controlled by the production demand of the melt pump. The melt polymer from the pump was fed into the heated spin pack assembly having 16 holes of 0.4 or 0.6 millimeters size. The yarn package assembly contained in the spin plate and the channel plates (32 channels) that kept the two polymer streams separated until they reached the spin plate. The extruded polymers were in the form of yarns, which were tempered or cooled by a supply of hot or cold air through a 1.5 meter long spinning chamber. The fiber strands were subsequently pulled in a quick way collected on a godet roller. After a fixed amount of time, the godet knee was stopped and the fibers were collected. These fibers were then subjected to analysis and compared to commercially available fibers. The results are set down in Tables 3-7.

Table 3: Polymer Configuration '' ci or polylactic available from Natureworks LLC. + Homopol - isotactic propylene available from Exxon Mobil Chemical Co.

Table 4: Extrusion conditions Table 5: Fiber properties Table 6: Fiber Properties (continued) Table 7: Commercial Fiber Properties As indicated above, the bicomponent fibers produced according to the present invention have a size, toughness and elongation percentage similar to commercially available fibers. In addition, the peak melting difference of the bicomponent fibers produced here was in the range of about 50 ° C, while most of the commercial bicomponent fibers had a peak melting difference in the range of about 30-40. ° C.

EXAMPLE 3 Several of the bicomponent fibers of Example 2 were cut into short fibers of 6 millimeters and placed by air in the form of unbonded non-woven fabrics. In addition, the following commercially available fibers were also formed in air-laid fabrics for comparative purposes: (1) Celbond® T-255 - bicomponent fibers having a polyethylene sheath and a polyester core, which are commercially available from KoSa, Inc., of Charlotte, North Carolina; (2) ESC-806 ALAD - bicomponent fibers having a polyethylene sheath and a polypropylene core available from ES Fibervision, Inc., of Athens, Georgia; and (3) Terramac ™ PL80- polylactic acid bicomponent fibers available from Unitika Ltd., from Osaka, Japan. Some of the samples used a 50% / 50% blend of bicomponent fibers with 1.5 denier per filament (dpf) of Tencel® H215 963 type fibers having a short length of 6 millimeters (Tencel® fibers available from Lenzing Fibers Inc. ., from Axis, Alabama), while other samples used 100% bicomponent fibers. The tissues placed by air were then joined through air ( ) in a combination of time and temperature to facilitate the union. The bound tissues were cut into 1 inch by 5 inch strips to carry out the stress test to evaluate the binding efficiency. The results are set down in tables 8-9.

Table 8: Multi-component Fiber Tension Properties 50% and 50% TENCEL Fabric Fiber / Table 9: Fiber Tissue Stress Properties of 100% Multiple Components 0 5 * Increased target base weight of 25 g / rt due to shrinkage As indicated, the bicomponent fibers of the present invention exhibited a good balance of tensile strength of the fabric, binding window and low binding temperature. For example, fibers exhibited better binding properties at lower temperatures than air-bound class binders, such as fibers T-255 and PLA. Lower bonding temperatures can result in lower heating costs, higher bonding speeds (conversion), and softer fabrics. Even at relatively low temperatures of 95 ° C and 115 ° C, the PL80 fibers resulted in an undesirable non-woven area shrinkage of 80% or more. In contrast, the fibers of the present invention shrunk to a much smaller extent. It is worth mentioning that some of the fibers formed according to the present invention had a relatively low tensile strength. For example, an SEM photomicrograph (40X) of the tissue formed using the fibers of sample number 13 (table 8) is shown in figure 2a. The bead polymer beads formation was found with the microphotography analysis which is believed to be a result of the high surface tension and the low viscosity of the sheath polymer melt. For improved bonding, the melted sheath polymer optimally flows to the fiber joint points and forms welds as shown in Figure 2b (sample number 12 (Table 8)). In addition, the sheath polymer used in sample number 13 (table 8) showed a trend light to form sticky fibers due to its low molecular weight.

EXAMPLE 4 The ability to form bicomponent fiber fabrics according to the present invention was demonstrated. Specifically, several of the fibers of Example 2 were cut into short fibers of 6 millimeters and placed by air in the form of unbonded non-woven fabrics having the size of 12 inches by 4 inches. Commercial bicomponent fibers (eg T-255 from Invista) were also tested as a control. The tissues placed by air were then subjected to air binding ( ) at 125 ° C for 30 seconds. Several properties were then measured including pre-and post-stabilization density, for example density before and after air-binding. The densities were measured by averaging the thickness along four (4) locations across the length of the tissue. The pre-stabilization of the tissues (at a pressure of about 0.05 pounds per square inch) was between the tissue densities of 0.07 and 0.08 grams per cubic centimeter. The resulting results are set down in table 10.

Table 10: Properties of Biodegradable Bicomponent Fiber Fabric Side by Side As indicated, the side-by-side fibers formed according to the present invention formed a relatively bulky fabric. For example, the sheath / core fiber of example number 12 (X0 gsm) had a volume of 1.8 millimeters while the fibers side by side had a volume varying from 2.7 to 3.3 millimeters, thus providing a hollow volume or greater . It is worth noting that the T-255 fibers possessed some curls that gave an improved pre-bond volume.

EXAMPLE 5 Several of the fibers were placed by air as described in Example 2, but were joined on "wire-weave" knit patterns in a press at a set pressure and temperature and at a fixed time interval. The fibers were initially cut to a length of 6 millimeters using a matrix and opened in a tissue former. 0.85 grams of the open fibers were collected on a strip of 4 inches by 12 inches from the former that was placed on a surface with pattern wire tissue unit. A press was set at a certain temperature (112 ° C to 158 ° C), with the upper plate being placed at a temperature of 35 ° C lower than the press to minimize the sticking of tissue. The strip was placed on the press and then compressed to 14,000 pounds per square inch in 5 seconds. The bonded strip was gently removed from the bonded pattern surface and cut into six different 1 by 5 inch strips for the strip tension test. The results are shown in Tables 11-13 and Figures 3-4.

Table 11: Fiber Properties (pump rpm = 5) 0 ou Table 11: Fiber Properties (pump rpm = 5) 0 As indicated, fibers containing 100% polylactic acid resulted in tissues that had a relatively low strength and elongation percentage. At higher bonding temperatures the tissue tension increased, but the tissue became stiff. In contrast, the fabrics formed with the fibers of the present invention were relatively strong, had a high elongation percentage and were mild.

Although the invention has been described in detail with respect to the specific embodiments thereof, it will be appreciated that those skilled in the art, upon achieving an understanding of the foregoing, can readily conceive alterations, variations and equivalents of these embodiments. Therefore, the scope of the present invention should be evaluated as that of the appended claims and any equivalents thereof.

Claims (36)

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

1. A biodegradable multi-component fiber comprising: a first component containing at least one high melting point aliphatic polyester having a melting point of from about 160 ° C to about 250 ° C; a second component containing at least one low melting point aliphatic polyester, the melting point of the low melting point aliphatic polyester being at least about 30 ° C lower than the melting point of the aliphatic polyester of high melting point, wherein the low melting point aliphatic polyester has a number average molecular weight of from about 30,000 to about 120,000 Daltons and an apparent viscosity of from about 50 to about 215 Pascal-seconds as determined at a temperature of 160 ° C and at a cut-off rate of 1000 seconds-1.

2. The biodegradable multi component fiber as claimed in clause 1, characterized in that the high melting point aliphatic polyester has a melting point of from about 180 ° C to about 220 ° C.

3. The biodegradable multiple component fiber as claimed in clause 1, characterized in that the high melting point aliphatic polyester is polylactic acid.

. The biodegradable multiple component fiber as claimed in clause 1, characterized in that the low melting point aliphatic polyester has an apparent viscosity of from about 75 to about 200 Pascal-seconds, as determined at a temperature of 160 ° C and at a cut-off rate of 1000 seconds-1.

5. The multi-component biodegradable fiber as claimed in clause 1, characterized in that the low melting point aliphatic polyester has an apparent viscosity of from about 80 to about 150 Pascal-seconds, as determined at a temperature of 160 ° C and at a cut-off rate of 1000 seconds "1.

6. The biodegradable multiple component fiber as claimed in clause 1, characterized in that the low melting point aliphatic polyester has a melting point of at least about 40 ° C less than the melting point of the high melting point aliphatic polyester.

7. The biodegradable multiple component fiber as claimed in clause 1, characterized in that the low melting point aliphatic polyester has a melting point of from about 120 ° C to about 160 ° C.

8. The biodegradable multiple component fiber as claimed in clause 1, characterized in that the low melting point aliphatic polyester has a number average molecular weight of from about 40,000 to about 100,000 Daltons.

9. The biodegradable multi component fiber as claimed in clause 1, characterized in that the low melting point aliphatic polyester has a polydispersity index of from about 1.0 to about 3.0.

10. The biodegradable multi component fiber as claimed in clause 1, characterized in that the low melting point aliphatic polyester has a melt flow index of from about 20 to about 120 grams per 10 minutes, measured at a force of 2160 grams and a temperature of 190 ° C according to the test method ASTM D1238-E.

11. The biodegradable multi-component fiber as claimed in clause 1, characterized in that the fiber has a toughness of from about 0.75 to about 7.0 grams-force per denier.

12. The biodegradable multi-component fiber as claimed in clause 1, characterized in that the fiber has a peak stress strain of from about 150 to about 500 megapascals.

13. The multi-component biodegradable fiber as claimed in clause 1, characterized in that the fiber has a peak stress strain of from about 200 to about 400 megapascals.

14. The biodegradable multiple component fiber as claimed in clause 1, characterized in that the low melting point aliphatic polyester has a glass transition temperature of less than about 150 ° C.

15. The multi-component biodegradable fiber as claimed in clause 1, characterized in that the aliphatic polyester knitted Low melt has a glass transition temperature of less than about 0 ° C.

16. The multi-component biodegradable fiber as claimed in clause 1, characterized in that the low melting point aliphatic polyester has a glass transition temperature of less than about -10 ° C.

17. The biodegradable multiple component fiber as claimed in clause 1, characterized in that the low melting point aliphatic polyester contains from about 10 mol% to about 40 mol% of an aromatic monomer constituent.

18. The biodegradable multi-component fiber as claimed in clause 1, characterized in that the aliphatic polyester constitutes at least about 95% by weight of the second component.

19. The biodegradable multiple component fiber as claimed in clause 1, characterized in that the low melting point aliphatic polyester is polybutylene succinate.

20. The multi-component biodegradable fiber as claimed in clause 1, characterized in that the second component is generally free of multicarboxylic acid.

21. The biodegradable multi component fiber as claimed in clause 1, characterized in that the fiber has a sheath / core configuration or side by side.

22. A method for forming the multi-component fiber as claimed in the clause 1, characterized in that the method comprises: extruding a first thermoplastic composition, the first thermoplastic composition comprising the high melting point aliphatic polyester; Y extruding a second thermoplastic composition, the second thermoplastic composition comprising the low melting point aliphatic polyester, wherein the second thermoplastic composition is extruded at a temperature ranging from about 120X to about 200 ° C; Y cooling the extruded thermoplastic compositions; Y pull the extruded and cooled thermoplastic compositions.

23. The method as claimed in clause 22, characterized in that the second thermoplastic composition is extruded at a temperature ranging from about 145 ° C to about 195 ° C.

24. The method as claimed in clause 22, characterized in that the fiber is pulled at a ratio of from about 200: 1 to about 6000: 1.

25. The non-woven fabric comprising multi-component biodegradable fibers wherein the multi-component fibers comprise: a first component containing at least one high melting point aliphatic polyester having a melting point of from about 160 ° C to about 250 ° C; a second component containing at least one low melting aliphatic polyester, the melting point of the low melting point aliphatic polyester being at least about 40 ° C lower than the melting point of the aliphatic polyester knitted of high melt, where the low melting point aliphatic polyester has a number average molecular weight of from about 30,000 to about 120,000 Daltons and a viscosity apparent from about 50 to about 215 Pascal-seconds, as determined at a temperature of 160 ° C and at a cut-off rate of 1000 seconds "1.

26. The nonwoven fabric as claimed in clause 25, characterized in that the high melting point aliphatic polyester has a melting point of from about 180 ° C to about 220 ° C.

27. The non-woven fabric as claimed in clause 25, characterized in that the high melting point aliphatic polyester is polylactic acid.

28. The non-woven fabric as claimed in clause 25, characterized in that the low melting point aliphatic polyester has an apparent viscosity of from about 75 to about 200 Pascal-seconds, as determined at a temperature of 160 °. C and at a cut-off rate of 1000 seconds-1.

29. The non-woven fabric as claimed in clause 25, characterized in that the low melting point aliphatic polyester has an apparent viscosity of from about 80 to about 150 Pascal-seconds, as determined at a temperature of 160 °. C and at a cutoff rate of 1000 seconds seconds-1.

30. The non-woven fabric as claimed in clause 25, characterized in that the low melting point aliphatic polyester has a melting point of from about 120 ° C to about 160 ° C.

31. The nonwoven fabric as claimed in clause 25, characterized in that the low melting point aliphatic polyester has a number average molecular weight of from about 45,000 to about 85,000 Daltons.

32. The non-woven fabric as claimed in clause 25, characterized in that the low melting point aliphatic polyester is polybutylene succinate.

33. The non-woven fabric as claimed in clause 25, characterized in that the second component is generally free of multicarboxylic acid.

34. The non-woven fabric as claimed in clause 25, characterized in that the fibers have a peak tension stress of from about 150 to about 500 Megapascals.

35. The non-woven fabric as claimed in clause 25, characterized in that the fibers have a peak voltage stress from about 200 to about 400 Megapascals.

36. An absorbent article comprising an essentially liquid impermeable layer, a liquid permeable layer, an absorbent core, wherein the absorbent core, the liquid permeable layer, or both comprise the nonwoven fabric as claimed in clause 25 . SUMMARIZES A multi-component fiber containing a high melt aliphatic polyester and a low melt aliphatic polyester is provided. Multicomponent fibers are essentially biodegradable, but easily processed into non-woven structures that exhibit fibrous and effective mechanical properties.