MXPA01008551A

MXPA01008551A - Synthetic fiber.

Info

Publication number: MXPA01008551A
Authority: MX
Inventors: Daniel Tsai Fu-Jya
Original assignee: Kimberly Clark Co
Priority date: 2000-08-25
Filing date: 2001-08-23
Publication date: 2002-04-10

Abstract

A novel synthetic fiber is disclosed including a first component of an aliphatic polyester polymer, a second component of a multicarboxylic acid, an admixture of the first component aliphatic polyester polymer and the second component multicarboxylic acid to form an unreacted specified thermoplastic composition, and melt blending the unreacted specified thermoplastic composition in an extruder or a mixer. The second component multicarboxylic acid lubricates the extruder and provides a nucleating agent for crystallizing the specified thermoplastic composition to form a mean crystal size less than about 120 Angstroms. Fiber composed of the specified thermoplastic composition has a mean crystal size less than about 120 Angstroms. The fiber has a glass transition temperature (Tg) less than about 55 C. In one aspect, a first component of polylactic acid and a second component of adipic acid provide synthetic fibers in a nonwoven structure used in a biodegradable and compostable disposable absorbent product for the absorption and removal of body fluids.

Description

SYNTHETIC FIBER BACKGROUND OF THE INVENTION 1. Technical Field This invention relates to a novel synthetic fiber. In one aspect, this invention relates to a woven fabric formed of novel synthetic fibers composed of a specified thermoplastic composition. 2. Background Disposable absorbent products currently find widespread use in many applications. In the infant care and child care markets, disposable diapers and underpants have replaced reusable fabric absorbent articles. Other widely successful disposable absorbent products include women's care products such as sanitary napkins or tampons, adult incontinence products, and health care products, such as surgical covers and bandages. for wounds.

A disposable absorbent product includes a composite structure comprising an upper sheet, a lower sheet and an absorbent structure between the upper sheet and the lower sheet. Disposable absorbent products include some type of fastening system for notching the product on the user.

Disposable absorbent products are subject to one or more discharges of liquid, such as water, urine, menstrual fluids, or blood, during use. As such, the bottom sheet materials of the outer shell of the disposable absorbent products are made of liquid-insoluble materials and are impermeable to liquid, such as polyolefin films, which have sufficient strength and sufficient handling capacity in a that the disposable absorbent product retains its integrity during use by a user and does not allow the filtering of the liquid that insults the product.

INTRODUCTION TO THE INVENTION Even though the disposable baby diapers currently available and other disposable absorbent products have been accepted by the public, these current products require improvements in specific areas. Many disposable absorbent products can be difficult to discard. Attempts to discard water from many disposable absorbent products in a toilet inside a drainage system can lead to the blockage of the toilet or the pipes that connect the toilet to the drainage system. The outer cover materials in the particular disposable absorbent products do not disintegrate or disperse when disposed of with discharging water into a toilet so that the disposable absorbent product can not be disposed of in this manner. If the outer cover materials are made too thin to reduce the overall volume in an attempt to reduce the possibility of blocking a toilet or drainage pipe, then the outer covering material does not exhibit sufficient strength to prevent tearing or tearing. the rupture when the outer covering material is subjected to the stresses of normal use by a user.

The waste of solid waste has become an ever increasing problem throughout the world. As the landfill continues to fill, demand for a reduction of the source of material in disposable products has increased. As an alternative, it is necessary to develop the recyclable or biodegradable components to be incorporated in the disposable products. as an alternative the products are necessary to be developed for final disposal by means other than incorporation and solid waste disposal facilities such as landfills. Therefore, there is a need for new materials to be used in the disposable absorbent products which retain the integrity and resistance during use, but after such use, said materials can be discarded more efficiently. There is a need for new materials used in the disposable absorbent product to be easily discarded and efficiently disposed of by composting. Alternatively, the disposable absorbent product can be easily and efficiently discarded in a liquid drainage system where the disposable absorbent product is capable of being degraded.

Problems have been encountered with the prepared fibers of the aliphatic polyesters. Aliphatic polyester polymers have been observed to exhibit a relatively slow crystallization rate in comparison to polyolefin polymers. The slow crystallization rate causes poor processability of the aliphatic polyester polymers.

The n-aliphatic polyester polymers provide sufficient thermal dimensional stability. The aliphatic polyester polymers suffer severe heat shrinkage due to a relaxation of the polymer chain during downstream heat treatment processes such as thermal bonding and lamination, unless an extra step such as settling is taken. with heat. However, a warm-up pass limits the use of fiber in the processes of nonwoven formation in the place, such as joining with spinning and blowing with fusion, where the settlement is very difficult. In addition, the use of processing additives retards the rate of biodegradation of the original material, or the processing additives themselves may not be biodegradable.

It is an object of the present invention to provide a novel synthetic fiber.

It is another object of the present invention to provide a novel synthetic fiber incorporating a specific thermoplastic composition.

It is an object of the present invention to provide a novel synthetic fiber incorporating a thermoplastic composition that provides the preferred processability.

It is an object of the present invention to provide a novel synthetic fiber incorporating a thermoplastic composition having a specified reduced crystal size.

It is an object of the present invention to provide a novel synthetic fiber incorporating a thermoplastic composition having a preferred thermal dimension stability.

It is an object of the present invention to provide a novel synthetic fiber incorporating a thermoplastic composition having a preferred biodegradability.

It is an object of the present invention to provide an absorbent article formed by the novel synthetic fibr incorporating a thermoplastic composition having a preferred processability, a thermal dimensional stability and a biodegradability.

It is also an object of the present invention to provide a non-woven structure formed from a novel synthetic fibr.

It is also an object of the present invention to provide a nonwoven fabric formed from a novel synthetic fiber.

It is a further object of the present invention to provide an absorbent article formed of a novel synthetic fibr and incorporating it.

It is a further object of the present invention to provide an absorbent article formed of a woven structure incorporating a novel synthetic fiber.

It is a further object of the present invention to provide an absorbent article formed of a non-woven fabric incorporating a novel synthetic fiber.

It is an object of the present invention to provide a fiber or non-woven structure which is degradable in the environment.

It is a further object of the present invention to provide an absorbent article formed of a non-woven fabric incorporating a novel synthetic fiber which is degradable in the environment.

These and other objects of the present invention will become more apparent from a careful inspection of the detailed description and figure of the drawings that follow.

SYNTHESIS OF THE INVENTION The present invention provides a novel synthetic fibr including a first component of an aliphatic polyester polymer and a second component of a multicarboxylic acid and melt mixing the specified thermoplastic composition not reacted in an extruder. In one aspect, the present invention provides a novel synthetic fiber formed by dry blending the first polymer component. of aliphatic polyester and the second component of multicarboxylic acid to form a specified unreacted thermoplastic composition. The second multicarboxylic acid component lubricates the extruder and provides a nucleating agent for the crystallization of the specified thermoplastic composition to form an average crystal size of less than about 120 Angstroms. The novel fiber composed of the specified thermoplastic composition has an average crystal size of less than about 120 Angstroms. The novel fiber has a glass transition temperature (Tg) lower than the transition temperature of the fiber glass without the multi-carboxy acid. In one aspect, the fiber has a glass transition temperature (Tg) of less than about 55 degree centigrade.

In one aspect, a first component of the polylactic acid and a second component of the adipic acid provides synthetic fibers in a non-woven structure used in a biodegradable and compostable disposable absorbent product for the absorption and removal of body fluids.

BRIEF DESCRIPTION OF THE DRAWINGS Figure 1 shows a schematic block diagram of the present invention.

Figure 2 shows a schematic block diagram of the present invention, highlighting fiber formation d.

DETAILED DESCRIPTION The present invention provides a novel synthetic fibr and a process for manufacturing the synthetic fiber of the present invention. The novel synthetic fiber of the present invention is manufactured to form a synthetic fiber composed of a specified thermoplastic composition.

In one aspect, the specified thermoplastic composition of the present invention includes a n-reacted mixture of an aliphatic polyester polymer and a multicarboxylic acid.

In one aspect, the extruded fibers of the present invention are formed into nonwoven structures used in a disposable absorbent product intended for the absorption of fluids such as body fluids.

The present invention incorporates a biodegradable thermoplastic composition which is easily prepared easily processable into preferred end structures, such as nonwoven structures or fibers.

The present invention incorporates a specified thermoplastic composition composed of a mixture of a first component and a second component. An incorporation of the specified thermoplastic composition includes a mixture of a first component of an aliphatic polyester polymer and a second component of a multicarboxylic acid, wherein the multicarboxylic acid has a total of carbon atoms d less than about 30. has found that the specified thermoplastic composition as used in the present invention provides the preferred properties in a novel synthetic fiber formed by the present invention.

In another aspect, the present invention provides a non-woven structure incorporating a synthetic fiber prepared from the specified thermoplastic composition.

In one embodiment, such a non-woven structure is used with a bottom sheet and an absorbent structure to provide a disposable absorbent product.

The present invention provides a novel synthetic thermoplastic composition extruded into fibers. It has been empirically found that incorporating a specified percent by weight of a multicarboxylic acid in the composition used in the present invention provides important advantages for extruding the fibers.

In the extrusion of the fibers in the present invention it has been found that the multicarboxylic acid beneficially exists in a liquid state during thermal processing of the thermoplastic composition but that during the cooling of the processed thermoplastic composition, the multicarboxylic acid becomes a solid or crystallizes at a higher temperature before the aliphatic polyester polymer is converted to a solid state or crystallized. In the specific thermoplastic composition used in the present invention, the multicarboxylic acid carried out two important and distinct functions.

First, when the thermoplastic composition is in a molten state, the multicarboxylic acid functions as a process lubricant or plasticizer, facilitating and processing the thermoplastic composition while increasing the flexibility and firmness of a fiber of a final product through the internal modification of the aliphatic polyester polymer. The multi-carboxylic acid replaces the secondary valence bonds by keeping the aliphatic polyester polymer chains together with the valences of the acid-to-aliphatic polyester polymer valence, facilitating the movement of the polymer chain segments. The unione of secondary valence are either intramolecular intermolecular. Intramolecular means an interaction between different segments of the same polymer chains. Intermolecular means the interaction between different polymer chains. This effect is evidenced, in an embodiment of the present invention, in a mixture of adipic acid and poly (lactic acid) acid wherein the melting temperature of the thermoplastic composition changes at lower temperatures with an increasing mixing ratio of the adipic acid to the poly (Lactic acid) With this effect, the torsional force required to flip an extruder, in fiber production, is dramatically reduced as compared to the processing of the poly (lactic acid) polymer alone. In addition, the process temperature required to spin the thermoplastic composition into a final product, such as a fiber or structure or a woven structure, is dramatically reduced, thereby decreasing the risk of undesirable thermal degradation of the poly (acid) polymer. lactic).

Second, when a final product of the present invention prepared from the thermoplastic composition of the present invention is being cooled and solidified from the liquid or molten state, the multicarboxylic acid functions as a nucleating agent. A nucleating agent, such as solid particles, mixed with a thermoplastic composition provides sites to initiate crystallization during cooling. However, such solid nucleating agents s easily agglomerate in the thermoplastic composition resulting in blockage of the filters and orifices of the spinning organ during spinning. The nucleating effect of such solid nucleating agents peaks at aggregate levels d about 1 percent of such solid nucleating agents. Both of these factors reduce the ability or motivation to add high percentages of weight of such solid nucleating agents to the thermoplastic composition.

In processing the specified thermoplastic composition of the present invention, however, it has been found that empirically there is the multicarboxylic acid in a liquid state during the extrusion process, wherein said multicarboxylic acid functions as a plasticizer, while the multicarboxylic acid is au capable of solidifying or crystallizing before the aliphatic polyester during cooling, wherein the multicarboxylic acid functions as a nucleating agent. For the cooling of the homogeneous melt, the multicarboxylic acid solidifies or crystallizes relatively more rapidly completely or just when falling below its melting point since this is a relatively small molecule. For example, the adipic acid has a melting temperature of about 16 degrees centigrade and a crystallization temperature of about 145 degrees centigrade.

Referring now to Fig. 1 and Fig. 2 the schematic block diagrams show a process flow display for the present invention.

In Figure 1, the first component composed of aliphatic polyester is shown to be combined with the second component composed of the multicarboxylic acid through two different modes. The first mode adds the aliphatic polyester prime component and the second multicarboxylic acid component separately either inside a melt mixer or into a melt extruder. The second mode dry mixes the first aliphatic polyester component and the second multicarboxylic acid component together before adding that resulting dry mix to a melt mixer or a melt extruder. From the extrusion of the molten state which takes place in both the melt mixer or the melt extruder, there are paths for the formation of a non-woven structure. The first path has the molten extrudate which is cooled pelletized or formed into a functional form to be fed to an extrusion device for the purpose of fiber formation. The second path directly goes to the fiber formation of a non-woven structure from the molten extrudate. The fiber-forming step is further expanded in the schematic block of FIG. 2.

Figure 2 schematically highlights the dual functionality of the second multicarboxylic acid component during the fiber and d melt formation phases when the first component and the second component are processed together. When the first aliphatic polyester component and the second multicarboxylic acid component are combined and exist in a molten phase, the first aliphatic polyester component is plasticized by the multicarboxylic acid. When the molten mixture is formed into fibers, said molten mixture is cooled and the second multi-carboxylic acid component solidifies and accelerates the crystallization of the first aliphatic polyester component. This acceleration of crystallization is manifested by an increase in crystal density and a decrease in crystal size. Typically, after fiber formation, the fibers are aerodynamically mechanically pulled, which further cools and crystallizes the fibers as they are formed into a non-woven structure.

The present invention produces a novel synthetic fiber, in one aspect, the present invention provides a novel synthetic fiber having an average crystal size of less than 120 Angstroms.

It has been empirically found that the novel synthetic fiber product manufactured by the specialized process of the present invention exhibits an effective glass size for the fiber product made from the thermoplastic composition specified to provide the preferred properties When thermally processed, such as a fiber having an average crystal size of less than 120 Angstroms.

The aliphatic polyester macromolecule polymer alone, when taken separately and apart from the specified composition used in the present invention has a slow crystallization rate. When cooled, the aliphatic polyester macromolecule polymer only solidifies and crystallizes more slowly and at a larger crystal size at a temperature lower than its melting temperature. For example, poly (lactic acid) alone, when taken separately and departing from the specified composition used in the present invention has a melting temperature of about 175 degrees centigrade and a crystallization temperature of about 121 degrees centigrade. In the formation of the fiber product manufactured by the present invention during cooling, the multicarboxylic acid used in the present invention initiates crystallization at a temperature above the natural crystallization temperature of the aliphatic polyester polymer and acts as a solid nucleating site within the the thermoplastic chiller composition.

The fiber made from the specific composition used in the present invention has been found to exhibit a crystal size that is effective for the fiber made from the specified composition of the present invention to provide preferred properties. The fiber made from the specified composition of the present invention has been found to exhibit a smaller average crystal size of about 120 Angstroms. The average crystal size of a material is determined according to the procedure described in section d test methods.

The novel synthetic fiber of the present invention having an average crystal size of less than about 120 Angstroms has been found to eliminate the problem of heat shrinkage encountered with fibers prepared from only aliphatic polyester polymers. The novel fiber has an average glass size of less than about 120 Angstrom which has been found to eliminate the heat shrinkage of thermally induced chain relaxation of the polymer segments in the amorphous phase and in the incomplete crystalline phase. The synthetic fiber Novelty maximizes the crystallization of material before the joining phase so that the thermal bonding energy goes directly into the fusion rather than allowing a chain relaxation and re-ordering the incomplete crystal structure. The fiber of the present invention has empirically found that it maximizes the crystallization of the aliphatic polyester polymer and minimizes heat shrinkage.

The present invention incorporates a specified thermoplastic composition which includes a first component and a second component. As used herein, the term "thermoplastic" means a material that is softened when exposed to heat and essentially returns to its original condition when cooled to room temperature.

The first component in the specified thermoplastic composition is an aliphatic polyester polymer. Suitable aliphatic polyester polymers include, but are not limited to, poly (lactic acid), polybutylene succinate, polybutylene succinate-co-adipate, and polyhydroxybutyrate. -valerate polyhydroxybutyrate-covalerate polycaprolactone, copolyester, polyester amide, cotton-based polymers, mixtures of such copolymer polymers of such polymers. Other potentially suitable polymers include the polyethylene terephthalate-based polymer, the sulfonated polyethylene terephthalate, the polyethylene oxide, the polyethylene, the polypropylene, the polyvinyl alcohol, and the aromatic aliphatic copolyester.

The present invention incorporates a novel composition composed of an aliphatic polyester polymer and of a multicarboxylic acid in a specified amount of 5-5 percent by weight, preferably providing the multicarboxylic acid in an amount of 10-40 percent by weight, more preferably 20% by weight. -40 percent by weight, more preferably 25-30 percent by weight. The aliphatic polyester polymer and incorporated into the specified thermoplastic composition in a weight amount of between about 50 percent by weight about 95 percent by weight. Below about percent by weight, an unacceptable shrinkage occurs. Arriving at around 50 percent by weight, the fibers become unacceptably weak.

In a preferred embodiment, the aliphatic polyester polymer is incorporated into the thermoplastic composition in a weight amount of from about 7 percent by weight to about 75 percent by weight.

In a preferred embodiment, the multicarboxylic acid is incorporated into the thermoplastic composition in an amount by weight of between about 25 percent po weight to about 30 percent by weight.

In a preferred embodiment, the present invention forms a novel synthetic fiber having an average crystal size of less than 120 Angstroms.

In one embodiment of the present invention, it is preferred that the aliphatic polyester polymer used be poly (lactic acid). The poly (lactic acid) polymer prepared by the polymerization of lactic acid. Or chemically equivalent material can be prepared by polymerizing the lactide. As such, as used herein, the term "poly (lactic acid) polymer" is intended to represent the polymer prepared by either the polymerization of the acidic or the lactide.

Lactic acid and lactide are asymmetric molecules that have two optical isomers referred to as the levorotatory enantiomer and the dextrorotatory enantiomer respectively. The levorotatory enantiomer is sometimes referred to as "L", and the dextrorotatory enantiomer is sometimes referred to as "D". The different polymers which are chemically similar but which have different properties may be prepared by the polymerization of a particular enantiomer or by using a mixture of the enantiomers. It has been found that by modifying the stereochemistry of a poly (lactic acid) polymer, we can control the melting temperature, the melting rheology, and the crystallinity of the polymer. By controlling such properties, we can prepare a multicomponent fiber that has a preferred melt strength, mechanical properties, smoothness, and procesabilidade properties to make attenuated, heat set, and crimped fibers.

The aliphatic polyester polymer must be present in the specified thermoplastic composition in an amount effective to result in the thermoplastic composition having the preferred properties. The aliphatic polyester polymer should be present in the thermoplastic composition in a weight amount that is less than 100 percent by weight in the range of from about 40 percent by weight to less than 100 percent by weight, preferably from about 100% by weight. 50 percent by weight about 95 percent by weight, more preferably between about 60 percent by weight about 90 percent by weight, even more preferably from about 60 percent by weight to about 80 percent by weight, and more preferably from between about 7 percent by weight to about 75 percent by weight, where all percentages by weight are based on the total weight amount of the aliphatic polyester polymer and the multicarboxylic acid present in the specified thermoplastic composition.

The aliphatic polyester polymer must have a weight average molecular weight effective for the specified thermoplastic composition to provide the preferred melting strength, fiber mechanical strength and fiber spinning properties. If the weight average molecular weight of an aliphatic polyester polymer is very high, the polymer chains are desirably entangled which can result in a thermoplastic composition incorporating that the aliphatic polyester polymer is difficult to process. Conversely, if the weight average molecular weight of an aliphatic polyester polymer is very low, the polymer chains are not sufficiently entangled, and the thermoplastic composition incorporating that aliphatic polyester polymer has a relatively weak melt strength, making the processing at high speed very difficult.

The aliphatic polyester polymers used in the present invention have weight average molecular weights d between about 10,000 to about 2,000,000 preferably from about 50,000 to about 400,000 and more preferably within about 100,000 about 300,000.

The weight average molecular weight for polymers or polymer blends is determined using the method as described in the test methods section herein.

The aliphatic polyester polyethylene polymer should have an effective polydispersity index value so that the specified thermoplastic composition provides a preferred melt strength, mechanical strength, fiber, and fiber spinning properties. As used herein by "polydispersity index" is meant the value obtained by dividing the weight average molecular weight of a polymer by the average molecular weight of polymer number Si the polydispersity index value of an aliphatic polyester polymer is very high, a thermoplastic composition incorporating this aliphatic polyester polymer is difficult to process due to the inconsistent processing properties caused by polymer segments including low molecular weight polymers that have lower melt strength properties during spinning . The aliphatic polyester polymer should have a polydispersity index value d between about 1 to about 15, preferably about 1 to about 4, and more preferably about 1 to about 3.

The number average molecular weight for polymers or polymer blends is determined using a method as described in the test methods section given herein.

The aliphatic polyester polymer must be processable with fusion. The aliphatic polyester polymer should have a melt flow rate of between about 1 gram per 10 minutes to about 200 grams per 10 minutes preferably between about 10 grams per 10 minutes about 100 grams per 10 minutes, and more preferably d between about 20 grams per 10 minutes to about 4 grams per 10 minutes. The melt flow rate of a material is determined according to the test method ASTM D1238-E which is incorporated herein in its entirety by reference.

In a preferred embodiment of the present invention, the aliphatic polyester polymer is biodegradable. The specified thermoplastic composition incorporating the aliphatic polyester polymer, in the form of a fiber or in the form of a non-woven structure, will be biodegradable when placed in a non-woven structure. the environment and exposed to air (oxygen) and / or water.

As used here, by "biodegradable" we mean that a material is degraded by the action of naturally occurring microorganisms such as fungal bacteria and algae.

In the present invention, the aliphatic polyester polymer must be corapostable. The specified thermoplastic composition incorporating the aliphatic polyester polymer, either in the form of a fiber or in the form of a woven structure, is compostable when placed in the environment and exposed to air or water or a combination of air and water As used herein, the term "compostable" is intended to mean a material capable of undergoing biological decomposition in a compound such that the material is not visually distinguishable and is broken into carbon dioxide, water, inorganic compounds and biomass. at a rate consistent with known compostable materials.

The second component in the thermoplastic composition is a multicarboxylic acid. An acid that incorporates two or more carboxylic acid groups. The present invention uses bicarboxylic acids, which provide carboxylic acid groups. The multicarboxylic acid must have a total carbon number not so large that the crystallization synthetics are decelerated. Synthetics of crystallization determine the speed at which crystallization occurs. The multicarboxylic acid must have a total carbon atoms of less than about 30, preferably d between about 3 to about 30, more preferably d between about 4 to about 20, and more preferably d between about 5 to about 10. Examples of the multicarboxylic acids of the present invention are the acid. malonic acid, citric acid, succinic acid, glutaric acid, adipic acid, pimelic acid, suberic acid, azelaic acid, roclic acid, itaconic acid, fumaric acid, phthalic acid, terephthalic acid, or the sebasic acid and mixtures thereof.

The multicarboxylic acid must be present in the specified thermoplastic composition in an effective amount to result in the thermoplastic composition having the preferred properties. The multicarboxylic acid is present in the specified thermoplastic composition in a weight amount greater than 0 percent by weight to about 60 percent by weight, preferably from about percent by weight to about 50 percent by weight, more preferably from about of 10 percent by weight about 40 percent by weight, even more preferably d between about 20 percent by weight to about 4 percent by weight, and more preferably from about d 25 percent by weight to about 30 percent by weight All the percentages are based on the amount of total weight of the aliphatic polyester polymer and the multicarboxylic acid present in the specified thermoplastic composition.

In order for the specific thermoplastic composition of the present invention to be processed in a product such as a fiber or a nonwoven structure having the preferred properties, it has been found that the multicarboxylic acid must exist in a liquid state or in a molten state during e thermal processing of the specified thermoplastic composition. The novel process is applied to any polymers to which the multicarboxylic acid may serve the dual functions of the multicarboxylic acid of the present invention.

It has further been discovered that during cooling of the specified thermoplastic composition, the multi-carboxylic acid is converted to a solid state or crystallized before the aliphatic polyester polymer converts a solid state or crystallizes.

In the thermoplastic composition of the present invention, the multicarboxylic acid performs two functions that are important.

The first important but distinct function is found when the thermoplastic composition is in a molten or liquid state, the multicarboxylic acid functions as a process lubricant or a plasticizer which facilitates the processing of the thermoplastic composition while increasing flexibility and firmness of a final product, for example, a fiber or a non-woven structure, through the internal modification of the aliphatic polyester polymer. The multicarboxylic acid replaces the secondary valenci bonds that hold the aliphatic polyester polymer chains together with the aliphatic-to-multicarboxylic polyester polymer valency bonds, thereby facilitating the movement of the polymer chain segments. The effect of the replacement has been found in a mixture of poly (lactic acid) and adipic acid wherein the melting temperature of the specified thermoplastic composition changes at lower temperature with an increasing mixing ratio of adipic acid to poly (acid). lactic). With this effect, the torque required to turn an extruder is dramatically reduced compared to the processing of the poly (lactic acid) polymer alone.

The process temperature required to spin the thermoplastic composition into a final product, such as a fiber or a non-woven structure, is dramatically reduced thereby decreasing the risk of undesirable thermal degradation of the aliphatic polyester polymers.

The second important but different function is found when a final product prepared from the specified thermoplastic composition, such as a fiber or woven structure, is being cooled and solidifies from its liquid or solid state, the multicarboxylic acid functions as a nucleating agent . The aliphatic polyester polymers have very slow crystallization rates. Two ways solve this issue One way changes the temperature cooling profile to maximize the synthetic crystallization. The other form added a nucleating agent to increase the sites and degrade the crystallization.

The process of cooling the extruded polymer to room temperature is achieved by blowing air at room temperature or sub-ambient on the extruded polymer.

The cooling or super cooling changes the temperature in May of 100 degrees Celsius and more frequently greater than 15 degrees Celsius over a relatively short time table (second) . To make the process in addition to the ideal cooling temperature profile, it is required that it be the only method to maximize the synthetic crystallisation of the aliphatic polyesters in a real manufacturing process that is very difficult due to the extreme cooling required within a very short period of time. However, the cooling can be used in combination with a second modification method. The second method will have a nucleating agent such as solid particulates, mixed with a thermoplastic composition to provide sites to initiate crystallization during cooling. However, such solid nucleating agents agglomerate very easily in the thermoplastic composition which can result in the blocking of the filters and the orifices of the spinning organ during spinning. The nucleating effect of such solid nucleating agents peaks at aggregate levels of about 1 percent d such solid nucleating agents. Both of these factors reduce the ability to add high weight percentages of said solid nucleating agents to the thermoplastic composition. In the processing of the specified thermoplastic composition of the present invention, it has been found that the multicarboxylic acid exists in a liquid (molten) state. during the extrusion process, wherein the multicarboxylic acid functions as a plasticizer, while the multicarboxylic acid is still able to solidify before the aliphatic polyester crystallizes during cooling, where the multicarboxylic acid functions as a nucleating agent. With the cooling of the homogeneous melt the multicarboxylic acid solidifies or crystallizes in a relatively faster and completely just form as it falls below its melting point, since this is a relatively small molecule. In one embodiment, the adipic acid has a melting temperature of about 162 degrees centigrade a melting temperature of about 145 degrees centigrade The aliphatic polyester polymer, being a macromolecule, has a relatively slow crystallization rate. When cooled, it solidifies or crystallizes more slowly and at a lower temperature than its melting temperature. In one embodiment, the poly (lactic acid) has a melting temperature of about 175 degrees centigrade and a crystallization temperature of about 121 degrees centigrade. During such cooling, the multicarboxylic acid begins to crystallize before the aliphatic polyester polymer and acts as solid nucleating sites within the thermoplastic chilling composition.

A thermally processed thermoplastic composition or a product made from such a thermoplastic composition such as fiber or a nonwoven structure, exhibits an effective glass size for the specific thermoplastic composition or a product made from the thermoplastic composition to exhibit the preferred properties. In one embodiment of the present invention, a thermally processed thermoplastic composition or a product made of such a thermoplastic composition, such as a fiber or a nonwoven structure, exhibits an average crystal size of less than about 120 Angstroms, preferably d less than about 110 Angstroms, more preferably less than about 100 Angstroms, even more preferably less than about 80 Angstroms, and more preferably less than about 70 Angstroms. The average crystal size of a material is determined according to the procedure described in the test methods section given here.

Although the principal components of the specified thermoplastic composition of the present invention have been described above, such a thermoplastic composition is limited to the components consisting of the major components. The specified thermoplastic composition can include other components that do not adversely affect the preferred properties of the thermoplastic composition. Exemplary materials used as additional components include pigments, antioxidants, stabilizers, waxes surfactants, flow promoters, solid solvents, plasticizers, nucleating agents, particles, and aggregates to improve the processability of the thermoplastic composition. An example of such optional component is a modified particle surface area available, for example, from Burgess Pigment Company of Sandersville, Georgia under the designation Modified Particle Surface Burgess Polyclay, or of Barretts Minerals Inc. of Dillon, Montana under the designation Modified Particle. d micropflex surface 1200. If such additional components are included in a specified thermoplastic composition, the additional components should be used in an amount of less than about 5 percent by weight, preferably at least about 3 percent by weight and more preferably d less than about 1 percent by weight, wherein all percent by weight are based on the total weight amount of the aliphatic polyester polymer, the multicarboxylic acid, the additional components present in the specified thermoplastic composition.

The thermoplastic composition specified in the present invention is a mixture of the aliphatic polyester polymer, the multicarboxylic acid, and optional additional components.

In order to achieve the preferred properties for the specified thermoplastic composition of the present invention it has been found to be critical that the aliphatic polyester polymer and the multicarboxylic acid remain essentially unreacted with each other such that a copolymer incorporating each of the polyester polymer aliphatic and multi-carboxylic acid has not been formed. As such, each of the aliphatic polyester polymer and the multicarboxylic acid remains distinct components of the specified thermoplastic composition.

In an embodiment of the present invention after dry blending of the aliphatic polyester polymer and the multicarboxylic acid together to form a sec mixture of specified thermoplastic composition, such a dry blend of the thermoplastic composition is preferably stirred, otherwise removed, mixed effectively to uniformly it combines the aliphatic polyester polymer and the multicarboxylic acid so that an essentially homogeneous dry mixture is formed. The dry mixture is then melt-blended in an extruder effectively to mix the aliphatic polyester polymer with the multicarboxylic acid uniformly so that the essentially homogeneous fused mixture is formed. The homogeneous melt mixture is cooled and pelletized. Alternatively, the homogeneous molten mixture is cooled and pelletized. Alternatively, the homogeneous molten mixture is sent directly to a spin pack or other equipment to form fibers or to form a non-woven structure. Alternate methods of mixing together the components used in the present invention include adding the multicarboxylic acid to the aliphatic polyester in an extruder used to mix the components together. An initial melt mixture of both of the components can carry the components together at the same time.

To determine whether the aliphatic polyester polymer and the multicarboxylic acid remain essentially n-reacted, nuclear magnetic resonance and infrared analysis techniques can evaluate the chemical characteristics of the final thermoplastic composition.

The melting or softening temperature of the thermoplastic composition should be within a range of from about 25 ° C to about 350 ° C, preferably from about 55 ° C to about 300 ° C, and more preferably from between about 100 ° C to about 200 ° C.

The thermoplastic composition of the present invention has been found to exhibit preferred processing properties compared to a thermoplastic composition incorporating the aliphatic polyester polymer, but none of the multicarboxylic acid. As used herein, the preferred method for determining improved processing of the thermoplastic composition is by measuring a decline in the glass transition temperature (Tg). At the transition temperature of the glass, the polymer chains in the thermoplastic composition begin the segmental movement which means that there is sufficient energy, usually thermal energy, to allow the polymer to flow in bulk. A decline in the transition temperature of the glass means that it takes less thermal energy to induce this segmentation movement and the resulting flow. A thermoplastic composition processed at a relatively lower temperature has components of the thermoplastic composition less vulnerable to thermal degradation. A thermoplastic composition having a glass transition temperature lowered is processed in the equipment such as an extruder operated at lower energy settings such as using less torque to turn the screw of the extruder.

The specified thermoplastic composition has a glass transition temperature lowered and requires less energy for the process and is more economical to use in fiber formation.

In one embodiment of the process of the present invention, the specified thermoplastic composition or product made from such a specified thermoplastic composition, such as a fiber or a nonwoven structure has a glass transition temperature (Tg) of less than about 55 ° C. preferably less than about 50 ° C, more preferably less than about 45 ° C, and more preferably less than about 40 ° C. The selection of starting polymer affects the transition temperature of the vidri (Tg). The different aliphatic polyesters have different glass transition temperatures (Tg) depending on the chemical composition of the polymer molecule, the average molecular weight of the weight, the average molecular weight of the number, the polydispersity index, the amount of residual monomer , and the amount of other impurities.

The selection of the multicarboxylic acid affects the amount of suppression of the glass transition temperature (delta Tg) of the thermoplastic composition compared to the glass transition temperature of the starting polymer.

In an embodiment of the composition and process of the present invention, the specified thermoplastic composition or the product made from the specified thermoplastic composition, such as a fiber or non-woven structure, has a suppression at the glass transition temperature (delta Tg). ) of at least 3 degrees centigrade, preferably d at least 5 degrees centigrade, more preferably at least about 10 degrees centigrade, and in some cases, more than 20 degrees centigrade.

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

Melt spinning of polymers includes the production of a continuous filament, such as meltblown-bonded yarn, and a non-continuous filament, such as basic and short fibers, and structures. To form a fibr bonded with yarn or melt blown, a thermoplastic composition is extruded and fed to a distribution system where the thermoplastic composition is introduced into a spinning organ plate. The spun fiber is then cooled, solidified, pulled by an aerodynamic system, and then it is form in a conventional non-woven. To produce a short or basic fiber, the yarn spun and cooled, solidified and pulled by a mechanical roller system to an intermediate filament and fibr collected diameter, rather than being directly formed into a non-woven structure. Subsequently, the fiber harvested is "cold drawn" at a temperature below its softening temperature, to the preferred finished fiber diameter, which process step can be followed by curling / texturing the cut to a desirable length of fabric.

The fibers can be cut in relatively short lengths, such as basic fibers which can have lengths in the range of about 25 about 50 millimeters and short fibers, which are still shorter and have lengths of less than about 1 mm. See, for example, U.S. Patent No. 4,789,592 issued to Taniguchi et al., And U.S. Patent No. 5,336,552 to Strack et al., Both of which are incorporated herein by reference in their application. whole.

A problem encountered with the preparation of the aliphatic polyester polymer only fibers is that of such fibers undergo heat shrinkage during thermal processing downstream. Shrinkage by heat mainly occurs due to the thermally induced chain relaxation of the polymer segments in the amorphous phase and the incomplete crystalline phase. To overcome this problem, the crystallization of the material is maximized before the joining phase so that the thermal energy goes directly to the melt rather than allowing a relaxation and rearrangement of the crystal structure incomplete. The material can be subjected to a settling treatment with heat. When the fibers subjected to a settling with heat reach the joining rod, the fibers will not shrink essentially due to the fact that such fibers are already fully or highly oriented. However, in the processes of bonding with spinning and co-blowing, a process of setting with heat in line is very difficult.

The present invention alleviates the need to, but does not prohibit, a settling step with heat because the use of the multicarboxylic acid in the specified thermoplastic composition allows the use of existing spunblown melt-blown actives without a modification of the main process. . Mixing the aliphatic polyester polymer with a multicarboxylic acid maximizes both the crystallization rate and the total crystallinity of the aliphatic polyester polymer which minimizes the expected heat shrinkage of the aliphatic polyester polymer.

When preparing basic or short fibers including in-line heat settling, in one embodiment of the present invention, the fibers prepared from the thermoplastic composition of the present invention undergo settlement with heat. The settlement with heat also reduces the heat shrinkage of the fiber. Settling with heating may be done when the fibers are subjected to a constant tension, which may be, but is not limited to about 1 to about 20 percent, at a temperature greater than about 50 ° C, preferably greater than about of 70 ° C, and more preferably greater than about 90 ° C. The higher heat setting conditions are preferred, including both the applied voltage and temperatures, while not sacrificing fiber processing. However, an excessive elevation of the set temperature with heat such as, for example, a temperature close to the melting temperature of a component of a fiber, reduces the resistance of the fibr and results in the fiber being hard to handle due to to the stickiness.

In an embodiment of the present invention, a fiber prepared from the thermoplastic composition specified in the present invention has an amount of shrinkage, at a temperature of about 100 degrees centigrade and for a period of time of about 15 minutes, quantified as a value Heat Shrink, less than about 1 percent, preferably less than about 10 percent, more preferably less than about 5 percent, and more preferably less than about 2 percent, where the amount of shrinkage is based on the difference between the initial and final lengths of the fiber divided by the initial length of the fiber multiplied by 100. The value of heat shrinkage for a fiber can be determined according to the procedure described in the section of test methods given here.

The thermoplastic composition specified in the present invention is particularly suitable for preparing fibers or non-woven structures used in disposable products including disposable absorbent products such as diapers, adult incontinence products, and bed pads; in catamenial devices, such as sanitary napkins and plugs; other absorbent products, such as cleaning cloths, bibs, wound dressings, and surgical covers or coatings. Therefore, in one aspect, the present invention provides a disposable absorbent product that incorporates the multicomponent fibers produced by the present invention.

In an embodiment of the present invention, the specified thermoplastic composition is formed in a fibrous matrix to be incorporated into a disposable absorbent product. A fibrous matrix can take the form of a fibrous non-woven fabric. The fibrous non-woven fabrics can be made completely from fibers prepared from the specified thermoplastic composition used in the present invention or they can be mixed with other fibers. The length of the fibers used may depend on the particular end use contemplated. E where the fibers are to be degraded in water such as, for example, in a toilet, the lengths are maintained at or below about 15 millimeters.

In one embodiment of the present invention, s provides a disposable absorbent product, which disposable absorbent product includes a liquid-permeable topsheet, a bottom sheet attached to the liquid-permeable topsheet, and an absorbent structure positioned between the topsheet permeable to the liquid. liquid and the lower sheet, wherein both the lower sheet and the upper sheet include the prepared fibers of the specified thermoplastic composition of the present invention.

Exemplary disposable absorbent products are described in U.S. Patent Nos. 4,710,187; 4,762,521; 4,770,656; and 4,798,603; whose references are incorporated here by this mention.

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

TEST METHODS Fusion temperature The melting temperature of a material was determined using differential scanning calorimetry. A differential scanning calorimeter, of T.A. Instrumentos Inc., of New Castle, Delaware, under the designation Calorimeter d Differential Exploration (DSC) Thermal Analyzer 2910, which was provided with a liquid nitrogen cooling accessory and was used in combination with a software program Thermal Analysis Analyzer 2200, was used for the determination of melting temperatures.

The samples of material tested were in the form of fibers or resin pellets. It is preferred not to handle material samples directly, but rather to use tweezers and other tools so as not to introduce anything that could produce erroneous results. Samples of material were cut, in the case of fibers, or placed, in the case of resin pellets, on an aluminum tray and weighed to an accuracy of 0.01 milligrams on an analytical balance. If required, a lid was curled over the sample of material on the tray. The differential scanning calorimeter was calibrated using an indian target standard, and a baseline correction was carried out as described in the manual for the differential scanning calorimeter. A sample of material was placed in the test chamber of the differential scanning calorimeter for the test and an empty tray was used as a reference. All the test was run with a nitrogen purge (industrial grade) of 55 cubic centimeters / minute on the test chamber. The heating and cooling program is a two cycle test that starts with the camera equilibrium at -75 ° C followed by the heating cycle of 20 ° C / minute at 220 ° C followed by a cooling cycle at 20 ° C. ° C / minute at -75 ° C, then another heating cycle of 20 ° C / minute at 220 ° C. The results were evaluated using the software program d analysis where the transition temperature of the glass (Tg) d inflection, and the endothermic and exothermic peaks were identified and quantified. The glass transition temperature was identified as the area on the line where a different pitch change occurs, and then the melting temperature was determined using an automatic inflection calculation.

Apparent viscosity A capillary rheometer, available from Gottfer of Roc Hill, South Carolina, under the designation Gottfer Rheograp 2003 capillary rheometer, was used in combination with a WinRHEO analysis software (version 2.31) to evaluate the rheological properties of apparent viscosity of the samples of material The placement of the capillary rheometer included a transducer of 2,000 pressure bars and a round hole capillary matrix of 30/1: 0/180.

If the sample of material that was being tested showed or was known to have sensitivity to water, the material sample was dried in a vacuum oven above its glass transition temperature, for example, above 55 ° C or 60 ° C. C for PLA materials, under vacuum of at least 15 inches of mercury with a nitrogen gas purge of at least 30 standard cubic feet per hour (SCFH) for at least 16 hours. When the instrument was heated and the pressure transducer was calibrated, the material sample was incrementally loaded into the column, packing resin in the column with one rod at a time to ensure consistent melting during the test. After loading the sample of material, a melting time of minutes preceded each test to allow the sample of material to fully melt at the test temperature. The capillary rheometer took data points automatically determined the apparent viscosity (in Pascal seconds) at 7 apparent cutoff rates (1 / second): 50, 100, 200, 500, 1000, 2000, 5000.

When the resulting curve is examined, and it is important that the curve be relatively smooth, if there are significant deviations from a general curve from another point, possibly due to the air in the column, the test run must be repeated to confirm the results.

The resulting rheology curve of apparent curtain rate against the apparent viscosity produced gave an indication of how the sample material will run at temperature in an extrusion process. The apparent viscosity values at a cut-off rate of at least 100 1 / second were the specific interest because these were the typical conditions found in commercial fiber spinning extruders.

Molecular Weights Average Weight / Number A ge permeation chromatography (GPC) method was used to determine the molecular weight distribution of the poly (lactic acid) samples having a weight average molecular weight (Mw) of between 800 to 400,000.

The gel permeation chromatography was placed with two analytical columns of PLgel Mixed linear K 5 microns, 7.5 x 300 millimeters in series. The column and d detector temperatures were 30 ° C. The mobile phase was tetrahydrofuran clas HPLX (THF). The pump rate was 0.8 millimeters per minute with an injection volume of 25 microliters. The running time was 30 minutes.

It is important to note that the new analytical column must be installed every four months, a new protection column every month, and a new online filter every month.

The polystyrene polymer standards, obtained from Aldrich Chemical Company, should be mixed in a dichloromethane (DCM): THF solvent (10:90) both HPLC class, to obtain concentrations of 1 milligram / milliliter. Multiple polystyrene standards can be combined in a standard solution as long as their peaks do not overlap when they chromatograph. A range of standards of around 687 400,000 must be prepared. Examples of standard blends with Aldrich polystyrenes of varying molecular weights (on average weight-molecular weight "M") include: Standard 1 (401,340, 32,660, 2,727), Standard 2 (45,730, 4,075), Standard 3 (95,800; 12,860) and Standard 4 (184,200; 24,150; 687).

Next, prepare the supply verification standard. Dissolve 10 grams of a PLA standard of 200,000 molecular weight, Catalog # 19245 obtained from Polyscience, Inc., to 100 milliliters of HPLC-type DCM to a glass jar with a Teflon coated lid using an orbiter shaker (at least 30 minutes). Pour the mixture on a clean dry glass plate, first let the solvent evaporate then place in a vacuum oven preheated to 35 ° C and dry for at least 14 hours under a vacuum of 25 mm Hg. Next, remove the PLA of the oven, and cut the film and small strips. Immediately grind the samples using a grinding mill (grid screen w / 10 grid) taking care not to add too much sample and cause the grinder to freeze. Store a few grams of the sample in a dry glass jar in a desiccator, while the rest of the sample can be stored in the freezer in a jar of similar type.

It is important to prepare a new standard of verification before the start of each new sequence, and because the molecular weight is greatly affected by the sample concentration, great care must be taken in its weighing and preparation. To prepare the verification standard, weigh 0.0800 grams ± 0.0025 grams of the reference standard PLA d 200,000 Mw into a clean dry scintillation container. After using a volumetric pipette or a dedicated repipet, add 2 milliliters of DSM to the container and screw the cap tightly. Allow the sample to dissolve completely. Spin the sample on an orbital shaker, such as a Thermolyne Roto mix mixer (type 51300), or a similar one, if necessary. To assess if it dissolved, hold the container to light at a 45 ° angle. Turn it slowly and look at the liquid as it flows down the glass. If the bottom of the container does not appear smooth, the sample did not completely dissolve. The sample can take several hours and dissolve. When dissolved, add 18 milliliters of TH using a volumetric pipette or a dedicated repipet, cover and container tightly and mix.

The sample preparations begin by weighing 0.0800 grams ± 0.0025 grams of the sample in a dry and clean scintillation vessel. The homogeneous melt mixture is cooled and pelletized. Alternatively, the homogeneous molten mixture is cooled and pelletized. Alternatively, the homogeneous molten mixture is sent directly to a spin pack or other equipment to form fibers or to form a non-woven structure. Alternate methods of mixing together the components used in the present invention include adding the multicarboxylic acid to the aliphatic polyester in an extruder used to mix the components together. An initial melt mixture of both of the components can carry the components together at the same time.

In one embodiment of the process of the present invention, the specified thermoplastic composition or product made from such a specified thermoplastic composition, such as a fiber or a nonwoven structure has a glass transition temperature (Tg) of less than about 55 ° C. , preferably less than about 50 ° C, more preferably less than about 45 ° C, and more preferably less than about 40 ° C. The selection of starting polymer affects the transition temperature of the vidri (Tg). The different aliphatic polyesters have different glass transition temperatures (Tg) depending on the chemical composition of the polymer molecule, the average molecular weight of the weight, the average molecular weight of the number, the polydispersity index, the amount of residual monomer , and the amount of other impurities.

As used herein, the term "fiber" "fibrous" means a material in which the length-to-diameter ratio of such material is greater than about 10. Conversely, by the term "fiberless" or "non-fiber" material. "non-fibrous" is meant a material in which the ratio of length to diameter of such material is about 10 or less.

Melt spinning of polymers includes the production of a continuous filament, such as meltblown-bonded yarn, and a non-continuous filament, such as basic and short fibers, and structures. To form a fibr bonded with yarn or melt blown, a thermoplastic composition is extruded and fed to a distribution system where the thermoplastic composition is introduced into a spinning organ plate. The spun fiber is then cooled, solidified, pulled by an aerodynamic system, and then shaped into a conventional nonwoven. To produce a short or basic fiber, the fiber spun and cooled, solidified and pulled by a mechanical roller system to a diameter of intermediate filament and fibr collected, rather than being directly formed in a non-woven structure. Subsequently, the fiber harvested is "cold drawn" at a temperature below its softening temperature, to the preferred finished fiber diameter, which process step can be followed by curling / texturing the cut to a desirable length of fabric.

A problem encountered with the preparation of the aliphatic polyester polymer only fibers is that of such fibers undergo heat shrinkage during thermal processing downstream. Shrinkage by heat mainly occurs due to the thermally induced chain relaxation of the polymer segments in the amorphous phase and the incomplete crystalline phase. To overcome this problemThe crystallization of the material is maximized before the joining phase so that the thermal energy goes directly to the melt rather than allowing a relaxation and rearrangement of the crystal structure incomplete. The material can be subjected to a settling treatment with heat. When the fibers subjected to a settling with heat reach the joining rod, the fibers will not shrink essentially due to the fact that such fibers are already fully or highly oriented. However, in the processes of bonding with spinning and co-blowing, a process of setting with heat in line is very difficult.

When preparing basic or short fibers including in-line heat settling, in one embodiment of the present invention, the fibers prepared from the thermoplastic composition of the present invention undergo settlement with heat. The settlement with heat also reduces the heat shrinkage of the fiber. Settling with heating may be done when the fibers are subjected to a constant tension, which may be, but is not limited to about 1 to about 20 percent, at a temperature greater than about 50 ° C, preferably greater than about of 70 ° C, and more preferably greater than about 90 ° C. The higher heat setting conditions are preferred, including both the applied voltage and temperatures, while not sacrificing fiber processing. However, an excessive elevation of the set temperature with heat such as, for example, a temperature close to the melting temperature of a component of a fiber, reduces the resistance of the fibr and results in the fiber being hard to handle. due to stickiness.

In an embodiment of the present invention, a fiber prepared from the thermoplastic composition specified in the present invention has an amount of shrinkage, at a temperature of about 100 degrees centigrade and for a period of time of about 15 minutes, quantified as a value Heat shrinkage, of less than about 1 percent, preferably less than about 10 percent more preferably less than about 5 percent, and more preferably less than about 2 percent, where the amount of shrinkage is based on the difference between the initial and final lengths of the fiber divided by the initial length of the fiber multiplied by 100. The value of heat shrinkage for a fiber can be determined according to the procedure described in the test methods section given here .

The thermoplastic composition specified in the present invention is particularly suitable for preparing fibers or non-woven structures used in disposable products including disposable absorbent products such as diapers, adult incontinence products, and bed pads; in catamenial devices, such as sanitary napkins and plugs; other absorbent products, such as cleansing cloths, bibs, wound dressings, and surgical covers or coatings. Therefore, in one aspect, the present invention provides a disposable absorbent product incorporating the multicomponent fibers produced by the present invention.

In an embodiment of the present invention, the specified thermoplastic composition is formed into a fibrous matrix to be incorporated into a disposable absorbent product. A fibrous matrix can take the form of a fibrous nonwoven fabric. The fibrous non-woven fabrics can be made completely from fibers prepared from the specified thermoplastic composition used in the present invention or they can be mixed with other fibers. The length of the fibers used may depend on the particular end use contemplated. E where the fibers are to be degraded in water such as, for example, in a toilet, the lengths are maintained at or below about 15 millimeters.

In one embodiment of the present invention, s provides a disposable absorbent product, whose disposable absorbent product includes a liquid-permeable topsheet, a bottom sheet attached to the liquid-permeable topsheet, and an absorbent structure placed between the top sheets. permeable to the liquid and the lower sheet, wherein both the lower sheet and the upper sheet include the prepared fibers of the specified thermoplastic composition of the present invention.

The products and absorbent structures according to all aspects of the present invention are subject to multiple discharges of a body fluid during use. Therefore, absorbent products and structures must be capable of absorbing multiple discharges of body fluids in amounts to which absorbent products and structures will be exposed during use. The downloads are separated from each other for a period of time TEST METHODS Fusion temperature The melting temperature of a material was determined using differential scanning calorimetry. A differential scanning calorimeter, of T.A. Instruments Inc., of New Castle, Delaware, under the designation Differential Scanning Calorimeter (DSC) Thermal Analyzer 2910, which was provided with a liquid nitrogen cooling accessory and was used in combination with a software program Thermal Analysis Analyzer 2200, was used for the determination of melting temperatures.

The samples of material tested were in the form of fibers or resin pellets. It is preferred not to handle material samples directly, but rather to use tweezers and other tools so as not to introduce anything that could produce erroneous results. Samples of material were cut, in the case of fibers, or placed in the case of resin pellets, on an aluminum tray and weighed to an accuracy of 0.01 milligrams on an analytical balance. If required, a lid was curled over the sample of material on the tray. The differential scanning calorimeter was calibrated using an indian target standard, and a baseline correction was carried out as described in the manual for the differential scanning calorimeter. A sample of material was placed in the test chamber of the differential scanning calorimeter for the test and an empty tray was used as a reference. All the test was run with a nitrogen purge (industrial grade) of 55 cubic centimeters / minute on the test chamber. The heating and cooling program is a two-cycle test that starts with the camera's equilibrium at -75 ° C, followed by the heating cycle of 20 ° C / minute at 220 ° C, followed by a cooling cycle at 20 ° C / minute at -75 ° C, then another heating cycle at 20 ° C / minute at 220 ° C. The results were evaluated using the software program d analysis where the transition temperature of the glass (Tg) d inflection, and the endothermic and exothermic peaks were identified and quantified. The glass transition temperature was identified as the area on the line where a different pitch change occurs, and then the melting temperature was determined using an automatic inflection calculation.

If the sample of material that was being tested showed or was known to have sensitivity to water, the material sample was dried in a vacuum oven above its glass transition temperature, for example, above 55 ° C or 60 ° C. C for PLA materials, under vacuum of at least 15 inches of mercury with a nitrogen gas purge of at least 30 standard cubic feet per hour (SCFH) for at least 16 hours. When the instrument was heated and the pressure transducer was calibrated, the material sample was loaded incrementally in the column, the packing resin in the column with a rod each time to ensure a consistent melting during the test. After loading the sample of material, a melting time of minutes preceded each test to allow the sample of material to fully melt at the test temperature. The capillary rheometer took data points automatically determined the apparent viscosity (in Pascal seconds. ) at 7 apparent cutting rate (1 / second): 50, 100, 200, 500, 1000, 2000, 5000.

The polystyrene polymer standards, obtained from Aldrich Chemical Company, should be mixed in a dichloromethane (DCM): THF solvent (10:90) both HPLC class, to obtain concentrations of 1 milligram / milliliter. Multiple polystyrene standards can be combined in a standard solution as long as their peaks do not overlap when they chromatograph. A range of standards of around 687 400,000 must be prepared. Examples of standard d-mixtures with Aldrich polystyrenes of variable molecular weights (on average weight-molecular weight "M") include Standard 1 (401,340, 32,660, 2,727), Standard 2 (45,730, 4,075) Standard 3 (95,800); 12,860) and Standard 4 (184,200; 24,150; 687) Next, prepare the supply verification standard. Dissolve 10 grams of a 200,000 molecular weight PLA standard, Catalog # 19245 obtained from Polyscience Inc., to 100 milliliters of HPLC-type DCM to a glass jar with a Teflon-coated lid using an orbital shaker (at least 30 minutes). Pour the mixture on a clean dry glass plate, first let the solvent evaporate then place in a vacuum oven preheated to 35 ° C and dry for at least 14 hours under a vacuum of 25 mm Hg. Next, remove the PLA of the oven, and cut the film and small strips. Immediately grind the samples using a grinding mill (grid screen w / 10 grid) taking care not to add too much sample and cause the grinder to freeze. Store a few grams of the sample in a dry glass jar in a desiccator, while the rest of the sample can be stored in the freezer in a jar of similar type.

It is important to prepare a new standard of verification before the start of each new sequence, and because the molecular weight is greatly affected by the sample concentration, great care must be taken in its weighing and preparation. To prepare the verification standard, weigh 0.0800 grams ± 0.0025 grams of the reference standard PLA d 200,000 Mw into a clean dry scintillation container. After using a volumetric pipette or a dedicated repipet, add 2 milliliters of DSM to the container and screw the cap tightly. Allow the sample to dissolve completely. Spin the sample on an orbital shaker such as a Thermolyne Roto mix mixer (type 51300), or a similar one, if necessary. To assess if it dissolved, hold the container to light at a 45 ° angle. Turn it slowly and look at the liquid as it flows down the glass. If the bottom of the container does not appear smooth, the sample did not completely dissolve. The sample can take several hours and dissolve. When dissolved, add 18 milliliters of TH using a volumetric pipette or a dedicated repipet, cover and container tightly and mix.

The sample preparations begin by weighing 0.0800 grams ± 0.0025 grams of the sample in a dry and clean scintillation vessel. You must be very careful in your weighing and preparation. Add 2 milliliters of DC to the container with a volumetric pipette or a dedicated repipet and screw the cap tightly. Allow the sample to dissolve completely using the same technique described in the preparation of the verification standard given above. Then add 18 milliliters of THF using a volumetric pipette or a dedicated repipet, cover the container tightly and mix Begin the evaluation by doing a test injection of a standard preparation to test the balance of the system. When the balance is confirmed inject the standard preparations. After these are run, inject the standard check preparation after the sample preparations. Inject the standard preparation after every seven sample injections and at the end of the test. Be sure not to take more than two injections of any container, since the two injections must be done within 4.5 hours of each other.

Four parameters of quality control evaluates the results. First, the correlation coefficient of the fourth order of regression calculated for each standard should not be less than 0.950 and no more than 1.050. Secondly, the relative standard relationship (RSD) of all the molecular weights of the standard verification preparations should not be more than 5.0 percent. Third, the average molecular weight of the standard preparation d verification injections should be within 10 percent of the molecular weight on the first injection of standard preparation d verification. Finally, record the response of the lactid for 200 micrograms per milliliter (pg / ml) of standard injection on a SQC data scheme. using the control links d scheme, the response must be within the defined SQ parameters.

Calculate the molecular statistics based on the calibration curve generated from standard polystyrene preparations and the Houwink brand constants for e PLA and polystyrene in THF at 30 ° C. Those are polystyrene (K = 14.1 * 10 alpha) = 0.700) and the PLA (K = 54.9 * 105, alpha = 0.639).

Heat shrinkage of fibers The equipment required for the determination of heat shrinkage includes a convection oven (Thelco laboratory model 160DM furnace), 0.59 grams (+/- 0.069 grams) of dipping weights, half-inch binder fasteners, masking tape, graph paper with at least a quarter of an inch square, a foam board (11 x 14 inches) or an equivalent substrate to hold the graph paper in the samples. The convection oven must be capable of a temperature of 100 degrees centigrade.

The fiber samples are spun with melting at their respective spinning conditions, a bundle of 3 filaments is preferred, and mechanically pulled to obtain the fibers with a jet stretch of upper 224. Only the fibers of the same jet stretch can be compared to one another in relation to their shrinkage by heat. The stretching of a fiber jet is the ratio of the speed of the pulled roller down divided by the linear extrusion cup (distance / time) of the molten polymer leaving the spinning organ. The spun fiber is collected on a coil using a binder. The bundle of fiber collected separated into 30 strands, if a bundle of 30 filaments has not already been obtained and has been cut into lengths of 9 inches.

The graph paper is curled over the tabler where one edge of the graph paper is married to the edge of the board. One end of the bundle of fibers is taped, n more than one inch in end. The tape end is attached to the board at the edge where the graph paper is married so that the edge of the bra rests on one of the horizontal lines of the graph paper while the bundle of fibers is held in place (the extreme and sitting must be », 68 hardly visible as it is secured under the fastener) The other end of the bundle is pulled tight and aligned parallel to the vertical lines on the paper graph. Then, a few inches down from the point where the fastener is joining the fiber, pinch the sinker at 0.59 grams per square meter around the bundle of fibers. Repeat the process of subjection for each duplicate. Three duplicates can be fastened at one time. Markings can be made on the graph paper to indicate the initial positions of the sinkers 10 The samples are placed in the oven at 100 degrees centigrade so that they hang vertically and do not touch the board. At the time intervals of 5, 10 and 15 minutes, quickly mark the new location of the sinkers on the graph paper and return the samples to the oven. 15 After the test is completed, remove the board and measure the distance between the origin (where the fastener held the fibers) and the marks at 5, 10, and 15 minutes with a ruler graduated to around 0.16 centimeters. S 20 recommend 3 duplicates per sample. Calculate the averages the standard deviations and the percentage of shrinkage. The percentage of shrinkage is calculated as (initial length of the fiber minus the final measured length of the fiber) divided by the initial length of the fiber and multiplied by 100. 25 values of heat shrinkage reported there use the values obtained at 15 minutes.

Determination of the crystal size The measurement of crystal sizes within a fiber sample was determined by ray diffraction using an X-ray machine, available from Philips, Inc. d Mahwah, New Jersey, under the designation XRG-3000 machine, equipped with a copper tube. Photographs were obtained, and an outline was made using a wide angle goniometer. To determine the effective crystal size of a fiber sample, a reflection pattern was obtained in the equatorial direction in relation to the fiber, scanning through the layer line (hkl). The plane (100) to around 16 degrees 2Q was selected, which is consistent with all the dimension calculations. Using the Scherrer equation, a mean dimension was then calculated for the crystallites perpendicular to the plane (100).

Biodegradability test The sample biodegradability test was carried out by Organist Waste Systems of Gent, Belgium, using the modified ASTM 5338.92 standard, or the ISO CD 14855 equivalent test procedure. The modification of the AST 5338.92 method is that the test chambers are maintained at a constant temperature of 58 ° C through the test rather than using an incremental temperature profile.

Example 1 A poly (lactic acid) polymer (PLA from Chronopol, Inc. of Golden Colorado) was obtained.The poly (lactic acid) polymer had a L: D ratio of 100 to 0, a melting temperature of about 175 ° C, a average molecular weight of weight of about 211,000, an average molecular weight of number d about 127,000, a polydispersity index of about 1.66, and a residual lactic acid monomer value of about 5.5 percent by weight.

The poly (lactic acid) polymer was mixed with various amounts of adipic acid. Mixing the polymer of lactic acid with the adipic acid involves dry blending of the components followed by mixing them together to provide a vigorous mixing of the components, which was accomplished in a twin screw extruder. contragiratory. The mixing was carried out on and is a twin screw combiner BRABENDER brand or a twin screw extruder HAAKEm, with the mixing screws.

The conversion of the prepared mixtures into fiber was carried out on a fiber spinning line. The spinning line consists of a single screw extruder three quarters of an inch in diameter with a ratio of 24: 1 L: (length: diameter) and three heating zones, which feed a Koch® static mixing unit. 0.62 inch diameter and then to a spinning head (fourth and quint heating heating zones) through a spinner organ of 15 to 30 holes, where each hole has a diameter of about 500 micrometers. The temperatures of each heating zone were sequentially indicated under the temperature profile section. The fibers were cooled by air at 13 ° C to 22 ° C and pulled by a mechanical jalad roller either to a winding unit or to a fiber jalad unit (as in the Lurgi spinning process). The process conditions for several of the prepared fibers are shown in Table 1.

Table 1 The prepared fibers were then evaluated for heat shrinkage, Tg, and the average crystal size. The results of these evaluations are plotted on table 2. The actual percentage of poly (lactic acid) / adipic acid polymer proportions were determined by using nuclear magnetic resonance as the ratio between the CH and CH2 peaks.

Table 2 Example II A poly (lactic acid) polymer was obtained from Chronopol, Inc. of Golden Colorado. The poly (lactic acid) polymer had a L: D ratio of 100 to 0, a melting temperature of about 175 ° C, a weight average molecular weights of about 181,000, an average molecular weight d number of about 115,000 , a polydispersity index d about 1.57, and a residual lactic acid monomer value of about 2.3 percent by weight.

The poly (lactic acid) polymer was mixed with various amounts of adipic acid. Polymer mixture of lactic acid with adipic acid involved dry blending of the components followed by co-melting of these together to provide vigorous mixing of the components, which was accomplished in a twin screw extruder. contragiratory. The mixing was conducted on either a BRABENDER brand twin screw combiner or a twin screw extruder HAKERmarca with the mixing screws. The conversion of the prepared mixtures into fibers was carried out on a fiber spinning line. The fiber line, the yarn line consisted of a 3-quarter-inch diameter d-extruder with a ratio of 24: 1 L: Dd (length: diameter) and heating zones, which were fed into a mixing unit and static Kock® of 0.62 inches in diameter and then to the spinning head (fourth and fifth heating zones) through a spinner organ of 15 to 3 holes, where each hole had a diameter of about 500 micrometers. The temperatures of each heating zone were sequentially indicated under section d temperature profile. The fibers were cooled by air 13 ° C to 22 ° C and pulled down by a mechanical jalad roller to either a winding unit or a fiber jalad unit (as in the Lurge spinning bonding process). The process conditions for several of the prepared fibers are shown in Table 3.

Table The prepared fibers were then evaluated for heat shrinkage, glass transition temperature and biodegradability. The results of these evaluations are shown in Table 4. The actual percentage of poly (lactic acid / adipic acid) polymer proportions were determined by using a nuclear magnetic resonance as the ratio between the CH and CH2 peaks.

Table 4 The present invention is capable of modification and variations without departing from the scope thereof. Therefore, the detailed description and example set forth above is intended to be illustrative and not only and not intended to limit the scope of the invention as set forth in the appended claims.

Claims

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

A synthetic fiber comprising: a fiber having a first aliphatic polyester polymer component in a specified thermoplastic composition, having an average crystal size of less than about 120 Angstroms, and having a glass transition temperature (Tg) of at least about degrees centigrade less than said first aliphatic polyester component.
2. A synthetic fiber as claimed in clause 1 formed by the process comprising: to. providing a first component of a polymer of an aliphatic polyester; b. provide a second component of a multicarboxylic acid; c. mixing said first aliphatic polyester polymer component and said second multicarboxylic acid component to form a specified unreacted thermoplastic composition; d. mixing said unreacted thermoplastic composition in a mixing extruder with melting; and. lubricating said extruder by said second component of multicarboxylic acid; F. providing a nucleating agent provided by said second multicarboxylic acid component; Y g. crystallizing said specified thermoplastic composition in the presence of said second multicarboxylic acid nucleating agent component to form an average crystal size of less than about 120 Angstroms.
3. A synthetic fiber as claimed in clause 2 characterized in that said fiber has a glass transition temperature (Tg) of at least 5 ° less than the first aliphatic polyester polymer component.
4. A synthetic fiber as claimed in clause 2 characterized in that said fiber has a glass transition temperature (Tg) of at least 10 ° less than the first aliphatic polyester polymer component.
5. A synthetic fiber as claimed in clause 2 characterized in that said fiber has a glass transition temperature (Tg) of at least 15 ° less than said first aliphatic polyester polymer component.
6. A synthetic fiber as claimed in clause 2 characterized in that said fiber has a glass transition temperature (Tg) of at least 20 ° less than said first aliphatic polyester polymer component.
7. A synthetic fiber as claimed in clause 2 characterized in that said second component of multicarboxylic acid comprises multicarboxylic acid which replaces the secondary intramolecular valence junctions, the intermolecular secondary valence junctions keeping said aliphatic polyester polymer together to form the bonds of valence of aliphatic-to-acid multicarboxylic polyester polymer.
8. A synthetic fiber as claimed in clause 2 characterized in that said second multicarboxylic acid component has a crystallization temperature higher than the natural crystallization temperature of said first aliphatic polyester component.
9. A synthetic fiber as claimed in clause 2 characterized in that said first component of polylactic acid.
10. A synthetic fiber as claimed in clause 9 characterized in that said first component of polylactic acid and said second component comprises adipic acid.
11. A synthetic fiber as claimed in clause 2 characterized in that it is made of pellet of said specified thermoplastic composition, wherein said fiber has an average crystal size of less than about 12 Angstroms.
12. A synthetic fiber as claimed in clause 11 characterized in that said pellets are capable of melting and melting spinning.
13. A synthetic fiber as claimed in clause 2 characterized in that it comprises a modified stereochemistry of said first component to control the melting temperature, the melting rheology and the crystallinity of said first component.
14. A synthetic fiber as claimed in clause 13 characterized in that said modified stereochemistry of said first component for controlling the melting temperature, the melting rheology, and the crystallinity of said first component forms a multicomponent fiber having a melt resistance preferred mechanical properties, softness and procesabilidade properties to form attenuated, heat set and crimped fibers.
15. A synthetic fiber as claimed in clause 2 characterized in that said fiber has a thermodynamic stability.
16. A synthetic fiber as claimed in clause 2 characterized in that said fiber has biodegradability.
17. A synthetic fiber as claimed in clause 2 characterized in that said aliphatic polyester polymer has a molecular weight of about 10,000 2,000,000 and in about 60 to 80 percent by weight of said specified thermoplastic composition; and said multicarboxylic acid has less than 30 molecular carbon atoms in about 20 to 40 percent by weight of said specified thermoplastic composition.
18. A synthetic fiber as claimed in clause 17 characterized in that said aliphatic polyester polymer is from about 70 to about 7 percent by weight of said specified thermoplastic composition.
19. A synthetic fiber as claimed in clause 18 characterized in that said multicarboxylic acid is from about 25 to 30 percent by weight of said specified thermoplastic composition.
20. A synthetic fiber as claimed in clause 2 characterized in that said fiber exhibits a value of shrinkage by heat at less than about 15 percent
21. A synthetic fiber as claimed in clause 2 characterized in that said aliphatic polyester polymer has a molecular weight of about 10,000 2,000,000 in about 50 to 95 percent by weight of specified thermoplastic composition and said multicarboxylic acid has less of 30 carbon atoms will molecularize in about 5 to about 50 percent by weight of specified thermoplastic composition, wherein said fibr exhibits a heat shrink value of less than about 15 percent.
22. A nonwoven fabric comprising: a nonwoven fabric formed of fibers having a first aliphatic polyester polymer component in a specified thermoplastic composition, having an average crystal size of less than about 120 Angstroms, and having a glass transition temperature (Tg) at least about 3 ° C less than said first aliphatic polyester polymer component.
23. A non-woven fabric as claimed in clause 22 characterized in that it is formed by the process comprising: to. providing a first component of a polymer of an aliphatic polyester; b. provide a second component of a multicarboxylic acid. c. mixing said first aliphatic polyester polymer component and said second multicarboxylic acid component to form a specified unreacted thermoplastic composition. d. mixing said unreacted thermoplastic composition in a mixing extruder with melting; and. lubricating said extruder by said second component of multicarboxylic acid; f. providing a nucleating agent provided by said second multicarboxylic acid component; Y g. crystallizing said specified thermoplastic composition in the presence of said second multicarboxylic acid nucleating agent component to form an average crystal size of less than about 120 Angstroms.
24. A non-woven fabric as claimed in clause 23 characterized in that said fiber has a glass transition temperature (Tg) of at least 5 ° less than said first aliphatic polyester polymer component.
25. A non-woven fabric as claimed in clause 23 characterized in that said fiber has a glass transition temperature (Tg) of at least 10 ° less than said first aliphatic polyester polymer component.
26. A non-woven fabric as claimed in clause 23 characterized in that said fiber has a glass transition temperature (Tg) of at least 1 degrees less than said first aliphatic polyester polymer component.
27. A non-woven fabric as claimed in clause 23 characterized in that said fiber has a glass transition temperature (Tg) of at least 20 ° less than said first aliphatic polyester polymer component.
28. A non-woven fabric as claimed in clause 23 characterized in that said second component of multicarboxylic acid comprises multicarboxylic acid and which replaces the secondary valence intramolecule junctions and the secondary intermolecular valence junctions by holding said aliphatic polyester polymer together to form the valence bonds of aliphatic-to-acid multicarboxylic polyester polymer.
29. A non-woven fabric as claimed in clause 23 characterized in that said second component of multicarboxylic acid has a crystallization temperature higher than the natural crystallization temperature of said first component of aliphatic polyester polymer.
30. A non-woven fabric as claimed in clause 22 characterized in that said first component comprises polylactic acid.
31. A non-woven fabric as claimed in clause 30 characterized in that said first component comprises said polylactic acid and said second component comprises adipic acid.
32. A non-woven fabric as claimed in clause 23 characterized in that said fibers are made of pellets of said further specified thermoplastic composition wherein said fibers have a glass size of less than about 120 Angstrome.
33. A non-woven fabric as claimed in clause 32 characterized in that said pellets are capable of melting and spinning with melted.
34. A non-woven fabric as claimed in clause 23 characterized in that it comprises a modified stereochemistry of said first component to control the melting temperature, the melting rheology, the crystallinity of said first component.
35. A non-woven fabric as claimed in clause 34 characterized in that said modified stereochemistry of said first component for controlling the melting temperature, the melting rheology and the crystallinity of said first component forms a multi-component fiber having a melt strength. preferred, mechanical properties, smoothness and procesabilidade properties to form attenuated, heat settled and crimped fibers.
36. A nonwoven fabric as claimed in clause 23 characterized in that said fiber has a thermal-dimensional stability.
37. A non-woven fabric as claimed in clause 23 characterized in that said fiber has biodegradability.
38. A non-woven fabric as claimed in clause 23 characterized in that said aliphatic polyester polymer has a molecular weight of around 10,000 to 2,000,000 at about 60 to 80 percent by weight of said specified thermoplastic composition; and said multicarboxylic acid has less than 30 carbon atoms molecularly in about 20 to 40 percent by weight of said specified thermoplastic composition.
39. A non-woven fabric as claimed in clause 38 characterized in that said aliphatic polyester polymer is from about 70 to about 7 percent by weight of said specified thermoplastic composition.
40. A non-woven fabric as claimed in clause 39 characterized in that said multicarboxylic acid is about 25 to 30 percent by weight of said specified thermoplastic composition.
41. A non-woven fabric as claimed in clause 23 characterized in that said fiber exhibits a shrinkage value per min heat of about 1 percent.
42. A non-woven fabric as claimed in claw 23 characterized in that said aliphatic polyester polymer has a molecular weight of about 10,000 to 2,000,000 about 50 to 95 percent by weight of said specified thermoplastic composition and said multicarboxylic acid it has less than 30 molecular carbon atoms in about 5 to 50 percent by weight of said specified thermoplastic composition wherein said fiber exhibits a value of shrinkage by heat of less than about 15 percent. 43 A synthetic fiber comprising: to. a first component of an aliphatic polyester polymer; b. a second component of a multi-carboxylic acid; c. a combination of said first aliphatic polyester polymer component and said second multicarboxylic acid component to form a specified thermoplastic composition; Y d. a synthetic fiber formed by said combination of said first component of aliphatic polyester polymer and said second component of multicarboxylic acid to form a n-reacted specified thermoplastic composition, melt-blending said unreacted specified thermoplastic composition in an extruder or mixer, lubricates said extruder with said second multicarboxylic acid component, providing a nucleating agent per second multicarboxylic acid component, and crystallizing said specified thermoplastic composition in the presence of said second multicarboxylic acid nucleating agent component to form an average crystal size of less than about d 120 Angstrome, a composite fiber of the specified thermoplastic composition having an average crystal size d less than about 120 Angstroms, a glass transition temperature (Tg) of at least about 10 ° C less than said first component of said aliphatic polyester polymer, the thermal-dimensional stability, the biodegradability, and a heat shrinkage value of less than about 15 percent. SUMMARY A synthetic fiber is described which includes a first component of an aliphatic polyester polymer, or a second component of a multicarboxylic acid, and a combination of the first aliphatic polyester polymer component and the second multicarboxylic acid component to form a specified thermoplastic composition not Reacted and melt-blended the specified unreacted thermoplastic composition in an extruder or in a mixer. The multi-carboxylic acid component eegund lubricates the extruder to provide a nucleating agent for the crystallization of the specified thermoplastic composition to form an average crystal size of less than about 120 Angstroms. The composite fibr of the specified thermoplastic composition has an average crystal size of less than about 120 Angstroms. The fiber has a glass transition temperature (Tg) d less than about 55 ° C. In one aspect, a first component of polylactic acid and a second component of adipic acid provide synthetic fibers in a non-woven structure used in a disposable biodegradable and compostable builder product for the absorption and removal of body fluids.