CZ193599A3 - Multicomponent fiber - Google Patents

Abstract

A thread in which at least one component creates an exposed one a surface on at least a portion of the multi-component fiber, allowing it thermally bonding said rmlticomponent fiber to others fiber The fiber comprises two polymay components lactic acid and differing ratios of lactic acid enantiomers L and D, which provides a multi-component fiber biodegradability. The second component is a polymer lactic acid with a ratio of L: More than the first component and has a melting point of at least 10 ° C higher than the first component. The method of manufacture comprises exposing each of the components of the temperature and the speed at which it exhibits the apparent viscosity and subsequent adhesion of the first component to the other. Multicomponent fibers usable in production nonwoven structures, for disposable absorbent products, intended for fluid absorption are body fluids.

Description

The present invention relates to a multi-component fiber. The multi-component fiber comprises two different polymers of poly (lactic acid), which provides biodegradable properties to the multi-component fiber, while allowing the multi-component fiber to be easily processed. The multicomponent fiber is useful in the manufacture of nonwoven structures that can be used in disposable absorbent products intended to absorb fluids such as body fluids.

BACKGROUND OF THE INVENTION

Disposable absorbent products currently find widespread use in many applications. For example, in the area of infant and child care such as diapers and sports shorts, they have generally replaced multiple-use fabric absorbent articles. Other typical disposable absorbent products include feminine hygiene products such as sanitary napkins and tampons, products used in the non-containment of body fluids in adults, and medical products such as surgical drapes or dressings. A typical disposable absorbent product generally comprises a composite structure, including a topsheet, a backsheet, and an absorbent structure between the topsheet and the backsheet. These products typically include some types of fastening system for attaching the product to its wearer.

Disposable absorbent products are typically exposed to one or more inflows of liquid such as water, urine, menstrual fluid or blood during use. Therefore, the material for the outer covering of the backsheet of disposable absorbent products is typically made of liquid-insoluble and liquid impervious materials, such as polypropylene films, that exhibit sufficient strength and processing capability such that the disposable absorbent product retains its integrity during use by the wearer and does not allow leakage of liquid that enters the product.

Although current disposable diapers and other disposable absorbent products have been generally accepted by the public, these products still require improvements in specific areas. For example, many disposable absorbent products can cause problems with their removal. For example, attempts to flush many disposable absorbent products into the toilet and into the sewage system typically result in blockage of the toilet bowl or pipe connecting the bowl to the sewer pipe. In particular, the outer packaging materials typically used in disposable absorbent products generally do not generally disintegrate or disperse when they are flushed down the toilet, so that disposable absorbent products cannot be removed in this manner. If the outer packaging materials are made very thin in order to reduce the total volume of the disposable absorbent product, to:

Thereby reducing the likelihood of blockage of the toilet bowl or sewer pipe, then the outer packaging material typically does not exhibit sufficient strength to prevent tearing or tearing when the outer packaging material is subjected to stress in normal use by a person, who wears it.

Furthermore, solid waste disposal is becoming an increasing problem worldwide. As storage becomes full, there is a growing need to reduce the volume of material in disposable products, to use more recyclable and / or degradable components in disposable products, and to design such products so that they can be stored in a different way than in the equipment for the disposal of solid waste, for example repositories.

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

Although degradable single-component fibers are known, problems exist with their use. Specifically, if a single component fiber is used in a thermally bonded application to bond the single component fiber to other fibers in an adhesive manner, the single component fiber will generally need to be exposed to temperatures that are generally close to the melting point of the fiber component, thereby causing the fiber to lose much their integrity during binding.

Although multicomponent fibers are known, we encounter problems in their preparation and use. In general, the components of a multi-component fiber must be chemically compatible; for the individual components to adhere effectively to each other, they must have similar rheological properties so that the multi-component fiber exhibits minimal strength and other mechanical and processing properties. At the same time, it is desirable that the various components generally exhibit different physical properties, such as melting points, so that the multi-component fiber may be useful for later processing into a nonwoven web. Therefore, it has proven to be a problem for those skilled in the art to combine components to meet these basic processing requirements as well as the need for the entire multicomponent fiber to be degradable.

Therefore, it is an object of the present invention to provide a multi-component fiber that is readily degradable in the environment.

The present invention also relates to a degradable multicomponent fiber which can be easily and efficiently prepared and which is suitable for use in preparing nonwoven structures.

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SUMMARY OF THE INVENTION

The present invention relates to a multicomponent fiber which is degradable yet easy to manufacture and, moreover, is easy to process into desired final structures such as nonwoven structures.

One aspect of the present invention relates to a multi-component fiber comprising a first component and a second component.

One embodiment of such a multi-component fiber comprises:

a. a first component having a given melting point and comprising a first polymer of poly (lactic acid) having a given L: D ratio, wherein the first component forms an exposed surface on at least a portion of the multi-component fiber; and

b. a second component having a melting point that is at least about 10 ° C greater than the melting point exhibited by the first component and comprising a second polymer of poly (lactic acid) having an L: D ratio that is greater than the L: D ratio exhibited; first polymer poles (lactic acid).

Another object of the present invention relates to methods of making the multicomponent fiber described herein.

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One embodiment of such a method of manufacture comprises:

exposing the first component to a first temperature and a first shear rate, the first component having a given first melting point, exhibiting an apparent viscosity at the first temperature and a first shear rate, and comprising a first polymer of poly (lactic acid) having a given L: D ratio;

b. exposing the second component to a second temperature and a second shear rate, the second component having a melting point that is at least about 10 ° C greater than the melting point exhibited by the first component, the second component exhibiting an apparent viscosity at the second temperature and second shear rate; between the apparent viscosity of the first component and the apparent viscosity of the second component is less than about 250 Pascal, and the second component comprises a second polymer of poly (lactic acid) having an L: D ratio that is greater than the ratio of L: D exhibited by the first polymer of poly acids) and

c. gluing the first component to the second component to form a multi-component fiber.

According to another aspect, the present invention relates to a nonwoven web comprising a multi-component fiber as described herein. One embodiment of such a nonwoven web is a topsheet useful in disposable absorbent products.

Detailed description of preferred embodiments

The present invention relates to a multi-component fiber comprising a first component and a second component. For purposes of illustration only, the present invention will generally be described.

as a two-component fiber comprising only two components. However, it is to be understood that the scope of the present invention includes a fiber having two or more components. Generally, the various components are extruded from separate extruders, but wound together to form a single fiber. The components are generally located in substantially permanently spaced separate regions in the cross-section of the multi-component fiber and extend in a continuous manner along the entire multi-component fiber. The configuration of such multicomponent fiber may be, for example, a sheath / core arrangement in which one component is substantially surrounded by the other component, a side-by-side arrangement, a cake arrangement or an "island in the sea" arrangement. Multicomponent fibers are generally described in US Patent 5,108,820 to Kaneko et al., US Patent 5,336,552 to Straek et al. and US Patent 5,382,400 to Pike et al., incorporated herein by reference in their entirety. Multicomponent fibers may also have shapes such as those described in US Patent 5,277,976 to Hogle et al. and US Patent 5,057,368 and 5,069,970 to Largman et al., which are incorporated herein by reference in their entirety and which generally describe fibers with unconventional shapes.

As used herein, the term fiber or fibrous means a discrete material wherein the length to diameter ratio of such discrete material is greater than about 10. Conversely, fiber or non-fibrous means a material that is a discrete material wherein the length to diameter ratio is about 10 or less.

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The first component of the multicomponent fiber generally forms an exposed surface on at least a portion of the multicomponent fiber, allowing thermal bonding of the multicomponent fiber to other fibers, which may be the same or different relative to the multicomponent fiber of the present invention. Consequently, to form thermally bonded structures such as nonwoven, the multicomponent fiber is required to have the first component a multicomponent fiber surface that is preferably at least about 25 percent, more preferably about 40 percent, suitably about 60 percent, more preferably about 80 percent, and up to about 100 percent. percent of the total surface area of the multi-component fiber.

Can be a fibrous fabric. Generally used nonwoven generally is exposed

In addition, the first component comprises a portion of the multi-component fiber that is between more than 0 and less than 100 wt%, preferably in the range of about 5 to about 95 wt%, more preferably in the range of about 25 to about 75 wt%. and suitably in the range of about 40 to about 60% by weight, the weight percent being based on the total weight of the first component and the second component present in the multicomponent fiber.

The second component in the multicomponent fiber generally imparts strength or stiffness to the multicomponent fiber and hence any nonwoven structure comprising the multicomponent fiber. Such a strength or stiffness of a multi-component fiber is generally achieved by having the second component having a melting point greater than the melting point of the first component.

components. Consequently, when the multi-component fiber is exposed to a suitable temperature, typically greater than the melting point of the first component but less than the melting point of the second component, the first component melts, while the second component generally remains in its solid form. The second component represents a portion of the multicomponent fiber that is between more than 0 and less than 100% by weight, preferably in the range of about 5 to about 95% by weight, more preferably in the range of about 25 to about 75% by weight. and suitably in the range of about 40 to about 60 wt%, wherein the weight percent is based on the total weight of the first component and the second component present in the multicomponent fiber.

According to the present invention, both the first component and the second component are also required to be biodegradable. As used herein, the term biodegradable is understood to mean a material that degrades by the action of naturally occurring microorganisms such as bacteria, fungi, and algae. As a result, the multi-component fiber, either in the form of a fiber or in the form of a nonwoven structure, is degradable when exposed to the environment.

It has been found that by using two polymers of poly (lactic acid) having different properties, a multicomponent fiber can be prepared such that the multicomponent fiber is substantially degradable while being a multicomponent fiber that is easy to process and exhibits efficient fiber mechanical Properties.

Polymer (lactic acid) polymer is generally prepared by polymerizing lactic acid. However, one of skill in the art will recognize that chemically equivalent material may also be prepared by polymerizing lactide. As used herein, the term "poly (lactic acid) polymer" is intended to represent a polymer that is prepared by either polymerizing lactic acid or lactide.

Lactic acid and lactide are known to be asymmetric molecules having two optical isomers, which are referred to as the left-handed enantiomer (referred to herein as L) and the right-handed enantiomer (referred to herein as D). As a result, by polymerizing a particular enantiomer or by using a mixture of both enantiomers, it is possible to prepare different polymers that are chemically similar but have different properties. In particular, it has been found that by altering the stereochemistry of the polymer by the poly (lactic acid), it is possible to change, for example, the melting point, the melt rheology and the crystalline structure of the polymer. When such properties are controlled and combined with the high chemical compatibility that occurs when two poly (lactic acid) polymers are used, it is possible to prepare a multicomponent fiber having the desired melt strength, mechanical properties, softness and processability to be produced weakened, thermally cured and shaped fibers.

According to the present invention, it is desired that the poly (lactic acid) polymer in the second component of the multicomponent fiber have an L: D ratio that is higher than the L: D ratio of the poly (lactic acid) polymer in the first component. This is because the L: D ratio determines the intrinsic crystallinity limits of the polymer, which in turn generally determines the melting point of the polymer. The degree of crystallinity of the polymer by the poly (lactic acid) is based on the regularity of the polymer backbone and its ability to align longitudinally with similarly shaped regions of either itself or other chains. If even a relatively small amount of the D-enantiomer (either lactic acid or lactide), such as about 3 to about 4% by weight, is copolymerized with the L-enantiomer (either lactic acid or lactide), the polymer backbone generally becomes irregularly shaped to a degree sufficient to cope with the other backbone segments of the pure Lenantiomer polymer. Therefore, the poly (lactic acid) polymer in the first component, comprising more Denantiomer, will be less crystalline than the poly (lactic acid) polymer in the second component.

Consequently, in the multi-component fiber of the present invention, it is critical that the poly (lactic acid) polymer in the first component contain more D-enantiomer than the poly (lactic acid) polymer in the second component. Therefore, the poly (lactic acid) polymer in the first component will have an L: D ratio that is less than the L: D ratio exhibited by the poly (lactic acid) polymer in the second component. Therefore, it is desired that the polymer of the poly (lactic acid) in the first component have an L: D ratio which is preferably less than about 100: 0, more preferably less than about 99.5: 0.5, suitably less than about 98: 2, and more preferably less than about 96: 4 and up to about 90:10, wherein the L: D ratio is based on the molar amount of the L and D monomers used to prepare the polymer of the poly (lactic acid) in the first component.

It is desired that the first poly (lactic acid) polymer having a relatively lower L: D ratio be present in the first component in an amount effective to provide the first component with the desired melt strength, mechanical fiber strength, and fiber spinning properties. . Accordingly, the first poly (lactic acid) polymer is present in the first component in an amount that is preferably greater than about 50% by weight, more preferably greater than about 75% by weight, suitably greater than about 90% by weight, more preferably greater than about 50% by weight. about 95 wt. and most preferably about 100% by weight, all percentages by weight based on the total weight of the first component.

Similarly, it is critical that the poly (lactic acid) polymer in the second component contain less D-enantiomer than the poly (lactic acid) polymer in the first component. As a result, the poly (lactic acid) polymer in the second component will have an L: D ratio that is greater than the L: D ratio exhibited by the poly (lactic acid) polymer in the first component. It is therefore desirable that the poly (lactic acid) polymer in the second component have an L: D ratio which is preferably at least about 96: 4, more preferably at least about 98: 2, suitably at least about 99.5: 0.5, and more preferably about 100: Wherein the ratio of L: D is based on the molar amount of L and D monomers used to prepare the poly (lactic acid) polymer in the second component.

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It is desired that the second poly (lactic acid) polymer having a relatively higher L: D ratio be present in the second component in an amount effective to provide the second component with the desired melt strength, mechanical fiber strength, and fiber spinning properties. . Accordingly, the second polymer of poly (lactic acid) is present in the second component in an amount that is preferably greater than about 50% by weight, more preferably greater than about 75% by weight, suitably greater than about 90% by weight, more preferably greater than about 50% by weight. about 95 wt. and most preferably about 100% by weight, all percentages by weight based on the total weight of the second component.

If both the first and second components of the multicomponent fiber of the present invention are essentially composed of the corresponding polymers of the poly (lactic acid), these components are not limited to these polymers and may include other components that do not adversely affect the desired properties of the first and second components; multicomponent fiber. Examples of materials that can be used as additional components include, but are not limited to, pigments, antioxidants, stabilizers, surfactants, waxes, flow promoters, solid solvents, particles and materials added to increase the processability of the first and second components. When such additional materials are included in the component, it is generally desired that such additional components be used in an amount that is preferably less than about 5% by weight, more preferably less than about 3% by weight. and suitably less than about 1% by weight, all percentages by weight being based on the total weight of the first or second component.

It is generally desirable that the second component have a melting or softening point that is preferably at least about 10 ° C, more preferably at least about 20 ° C and suitably at least about 25 ° C greater than the melting or softening point of the first component. Generally, polymers or polymer blends that are substantially crystalline in nature will either have a specific melting point or a very narrow melting or softening range. In contrast, polymers or polymer blends that are less crystalline or alternatively more amorphous in nature will generally have a broader melting or softening range. It will be appreciated that polymers of poly (lactic acid) comprising even relatively small amounts of D enantiomers cannot exhibit intrinsic melting points. However, the melting point can be induced by exposing the polymer to poly (lactic acid) polymers under certain processing conditions. For example, if the fiber containing the poly (lactic acid) polymer is extruded and drawn, the fiber becomes oriented in response to the forces acting on it. Such orientation can induce crystalline formation in the fiber, which can be detected, for example, by differential scanning calorimetry methods. For the polymers or polymer blends useful in the present invention, the melting point can be determined by differential scanning calorimetric methods, such as the method described in the Test Methods section.

Although the absolute melting or softening temperatures of the first and second components are generally not as important as the ratio of the two temperatures, it is generally required that the melting or softening temperatures of the first and second components be within the range typically found in the most important practical applications. Therefore, it is generally desired that the melting or softening temperatures of the first and second components are both preferably in the range of about 25 ° C to about 350 ° C, more preferably in the range of about 55 ° C to about 300 ° C and suitably in the range of about 100 ° C. ° C to about 200 ° C.

It is also desirable that the polymers of the poly (lactic acid) in both the first and second components exhibit weight average molecular weights that are suitable for both the first and second components to both exhibit the desired melt strength, mechanical fiber strength, and fiber spinning properties. . Generally, if the weight average molecular weight of the polymer poles (lactic acid) is too high, then this means that the polymer chains are strongly intertwined, which may result in the component being vice versa if the weight average polymer of the poles (lactic acid) is too low, this means that the polymer chains are not sufficiently entwined, which may result in the component exhibiting a relatively weak melt strength, making high processing speeds difficult. Therefore, both the poly (lactic acid) polymers in both the first and second components exhibit weight average molecular weights preferably in the range of about 10,000 to about 500,000, more preferably in the range of about 50,000 to difficult to process molecular weight. About 400,000 and suitably in the range of from about 100,000 to about 300,000. For the polymers or polymer blends useful in the present invention, the weight average molecular weight may be: the mass determined using the method described below in the test methods section.

It is also desirable that both the polymers of the poly (lactic acid) in both the first and second components exhibit polydispersity index values that are effective to have the first and second components both exhibit the desired melt strength, mechanical fiber strength, and fiber spinning properties. . As used herein, the polydispersity index refers to the value obtained by dividing the weight average molecular weight of the polymer by the number average molecular weight of the polymer. In general, if the polydispersity index value of the component is too high, the component may be difficult to process due to the segment of the component comprising low molecular weight polymers having a lower melt strength during spinning. Therefore, the poly (lactic acid) polymers in both the first and second components should exhibit polydispersity index values that are preferably in the range of about 1 to about 10, more preferably in the range of about 1 to about 4 and suitably in the range of about 1 to about 3. For the polymers or polymer blends useful in the present invention, the number average molecular weight can be determined by the method described below in the Test Methods section.

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It is also desired that the polymers of the poly (lactic acid) in both the first and second components exhibit a percentage of residual monomers effective to have the first and second components each exhibit the desired melt strength, mechanical fiber strength, and fiber spinning properties. As used herein, the term percent residual monomers refers to the amount of lactic acid monomer or lactide that has not yet been reacted and remains trapped within the structure of the interwoven polymers of the poly (lactic acid). In general, if the percentage of residual monomers in the polymer of the poly (lactic acid) in one of the components is too high, the component may be difficult to process due to the inconsistent processing properties due to the large amount of monomer vapors released during processing, which cause changes in extrusion pressures. However, a small amount of residual monomer in the poly (lactic acid) polymer in its component may be advantageous since such residual monomer functions as a plasticizer during the spinning process. Therefore, the polymers of the lactic acid in both the first and second components should have percent residual monomers which are preferably less than about 15 percent, more preferably less than about 10 percent and suitably less than about 7 percent.

It is also desired that the polymers of the poly (lactic acid) in the first and second components exhibit melt rheologies that are substantially similar and cause the first and second components, when combined, to exhibit the desired melt strength, mechanical fiber strength, and fiber spinning properties. The polymer melt rheology of the poly (lactic acid) can be quantified by the apparent viscosity of the polymer of the poly (lactic acid) and, as used herein, means the apparent viscosity of the component at shear rate and at the temperature at which the component is heat treated, such as which component is processed through the spinneret. It has been found that polymers having substantially different apparent viscosities are not readily processable. Although it is desired that both the first and second components exhibit apparent viscosities that are substantially similar, it is not necessary that such apparent viscosities be identical. Furthermore, it is generally not important whether the first or second component has a higher or lower apparent viscosity value.

Instead, it is desired that the difference between the apparent polymer viscosity of the poles (lactic acid) in the first component, measured at shear rate and at the temperature at which the first component will be heat treated, and the apparent polymer viscosity of the poles (lactic acid) in the second component, measured at shear rate and at the temperature at which the second component will be heat treated is preferably less than about 250 Pascal, more preferably less than about 150 Pascal, suitably less than about 100 Pascal, and more preferably less than about 50 Pascal. with.

Typical conditions of the thermal treatment the first and second components include using a shear rate which is preferably in the range from about 100 to ¹ to about 10,000 s \ more preferably in the range from about 500 s to about ^_1 • ·

5000 s ^-1 , suitably in the range of about 1000 s ^-1 to about 2000 s ^-1 and most preferably at about 1000 s ^-1 . Typical heat treatment conditions of the first and second components also include the use of a temperature that is preferably in the range of about 100 ° C to about 500 ° C, more preferably in the range of about 150 ° C to about 300 ° C and suitably in the range of about 175 ° C to about 250 ° C.

Methods for producing multicomponent fibers are well known and need not be described in detail herein. To form the multi-component fiber, at least two polymers are generally extruded separately and fed to a polymer distribution system where the polymers are introduced into a segmented spinneret plate. The polymers follow separate paths to the spinnerets and are combined in the orifices of the nozzles, which include either at least two concentric circular orifices to form a sheath / core fiber or a circular spinneret orifice divided along the projection into at least two compartments to form the one-side fiber. second. The fused polymer strands are then cooled, allowed to solidify, and generally drawn by means of a mechanical winding system, to a preliminary fiber strand diameter and wound up. Subsequently, the strand may be cold drawn at a temperature below its softening point to the desired final fiber diameter and shaped or crimped and cut to the desired fiber length. Multicomponent fibers can be cut to relatively small lengths, such as staple fibers, which generally have a length in the range of about 25 to about 50 millimeters, and short cut fibers that are even shorter and generally have lengths less than about 18. ··· ··· millimeters. See, for example, US Patent 4,789,592 to Taniguchi et al. and US Patent 5,336552 to Straek et al., both of which are incorporated by reference in their entirety.

a typical undergo

Polymer poles (dairy polyester type, thermal material)

Thermal induced acids) is which often shrinkage at the end phase of heat shrinkage treatment occurs mainly due to the thermal relaxation of the polymer segment chains in the amorphous phase and incomplete crystalline phase. To overcome this problem, it is generally desirable to maximize crystallization of the material prior to the bonding stage so that thermal changes pass directly into melting, instead of allowing chain relaxation and rearrangement of the incomplete crystalline structure. One solution to this problem is to expose the material to heat curing. In such a case, if the fibers subjected to thermal curing reach the take-up reel, the fibers will not substantially shrink, since such fibers are already fully or highly oriented.

Therefore, in one embodiment of the present invention, it is desired that the multicomponent fibers of the present invention undergo thermal curing. It is desirable that such heat curing occur when the fibers are subjected to a constant stress of at least 5 percent at a temperature that is preferably greater than about 50 ° C, more preferably greater than about 70 ° C and suitably greater than about 90 ° C. In general, it is recommended that the highest possible thermal curing temperatures be used at which fiber workability is not sacrificed. However, heat curing temperatures that are too high, such as •

a temperature close to the melting point of the first component of the multicomponent fiber may reduce the fiber strength and may make the fiber difficult to process due to stickiness.

In one embodiment of the present invention, the multicomponent fiber is required to have a shrinkage size at about 70 ° C, which is preferably less than about 10 percent, more preferably less than about 5 percent, suitably less than about 2 percent, and more preferably less than about 1 percent wherein the shrinkage size refers to the difference between the initial and final length divided by the initial length and multiplied by 100. The method by which the shrinkage size exhibited by the fiber can be determined is given in the test methods section below.

The multicomponent fibers of the present invention are suitable for use in disposable products, including disposable absorbent products such as diapers, non-fluidized adult products, and bed pads; in menstrual products such as sanitary napkins and tampons; and in other absorbent products such as wipes, bibs, wound dressings and surgical gowns or drapes. Accordingly, in one aspect, the present invention relates to a disposable absorbent product comprising the multi-component fibers of the present invention.

In one embodiment of the present invention, the multi-component fibers are processed to form a fibrous matrix for insertion into a disposable absorbent product. The fibrous matrix may take the form of, for example, a fibrous nonwoven. The fibrous nonwoven fabrics may be made fully of the multi-component fibers of the present invention or may be blended with other fibers. The length of the fibers used may depend on the particular intended end user. If the fibers are to be degradable in water, such as in a toilet, it is preferred that the fiber lengths be maintained at or below about 15 millimeters.

In one embodiment of the present invention, a disposable absorbent product is administered, and the disposable absorbent product comprises a liquid pervious topsheet and a bottom layer affixed to the liquid pervious topsheet and an absorbent structure positioned between the liquid pervious topsheet and the backsheet. a layer, wherein the liquid-permeable topsheet comprises multicomponent fibers of the present invention.

Examples of disposable absorbent products are generally described in US-A-4,710,187; US-A-4,762,521; U5-A-4,770,656; and US-A-4,798,603; these references are incorporated herein by reference.

Absorbent products and structures according to all aspects of the present invention are generally exposed to multiple surges of body fluid during use. Accordingly, it is desirable that the absorbent products and structures be

capable of absorbing multiple flushes of body fluid in amounts to which absorbent products and structures are exposed during use. Flushing is generally separated from one another by a time interval.

DETAILED DESCRIPTION OF THE INVENTION

Testing procedures

Melting point

The melting point of the material was determined using differential scanning calorimetry. A differential scanning calorimeter supplied by T.A. was used to determine the melting points. Instruments lne. from New Castle, Delaware, under the name Thermal Analyst 2910 Differential Scanning Calorimeter (DSC), which was equipped with liquid nitrogen cooling and used with the Thermal Analyst 2200 analysis program.

The material samples tested were either in the form of fibers or resin tablets. It is preferable not to process the material samples directly, but rather to use kneading ticks and other tools so that nothing that could give erroneous results is added. Material samples were sheared in the case of fibers or, in the case of a resin tablet, placed in an aluminum pan and weighed to an accuracy of 0.01 mg on an analytical balance. If necessary, a lid was formed over a sample material in a pan.

The differential scanning calorimeter was calibrated using an indium metal standard and baseline compensation was performed as described in the differential scanning calorimeter manual. A sample of material was placed in the test chamber of the differential scanning calorimeter for testing and the empty pan was used as a reference. All tests were carried out under a stream of nitrogen (industrial grade) of 55 cubic centimeters per minute passing through the test chamber. The warm-up and cool-down program is a two-cycle test that begins with equilibrating in the chamber at -75 ° C, followed by a warming cycle of 20 ° C / minute to 220 ° C, followed by a cooling cycle of 20 ° C / minute to -75 ° C. an additional heating cycle of 20 ° C / minute to 220 ° C.

The results were evaluated using analysis software programs in which the glass transition temperature (Tg) of the inflexion, endothermic and exothermic peaks was determined and quantified. The glass transition temperature was identified as an area on a straight line where significant slope of the curve occurs, and the melting point is then determined using an automated inflexion calculation.

Obvious viscosity

The capillary rheometer supplied by Gottfert, Rock Hill, South Carolina, under the name Gottfert Rheograph 2003 capillary rheometer, which was used in combination with VanRHEO (version 2.31) analysis software, was used to evaluate rheological properties regarding the apparent viscosity of material samples. The capillary rheometer equipment included a 2000 bar pressure transducer and a 30/1: 0/180 circular capillary nozzle.

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If the sample of the material being tested shows or is known to be water sensitive, the material sample is dried in a vacuum oven above the glass transition temperature, i.e., above 55 or 60 ° C for the materials from the lactic acid, under reduced a pressure 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.

The pressure transducer is gradually added to the column with the resin

Once the device is heated and calibrated, the sample material is a column, adding to the ram each time to ensure consistent melting during testing. After loading the material sample, the 2-minute melting preceding each test will allow the material sample to fully melt at the test temperature. The capillary rheometer reads the data automatically and determines the apparent viscosity (in Pascal.s) at 7 apparent shear rates (s ^_1 ): 50, 100, 200,

500, 1000, 2000 and 5000. When examining the resulting curve, it is important that the curve is relatively smooth. If there are significant deviations from the general curve from one point to the other, probably due to column air, the test should be repeated to confirm the results. The resulting rheological curve of the apparent shear rate and apparent viscosity gives an indication of how the material sample will behave at a given temperature in the stretching process. Values of apparent viscosity at a shear rate of at least 1000 s ^-1 are of particular interest since these are typical conditions occurring in commercial fiber extruders.

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Molecular weight

Gas permeation chromatography (GPC) is a method that is used to determine the molecular weight distribution of poly (lactic acid) samples, whose weight average molecular weight (Mw) is between 800 and 400,000.

The GPC is composed of two analytical columns PLgel Mixed K linear 5 microns, 7.5 x 300 millimeters in series. The column and detector temperatures are 30 ° C. The mobile phase is tetrahydrofuran (THF) in HPLC grade. The pump performance is 0.8 milliliters per minute with an injection volume of 25 microliters. The total processing time is 30 minutes. It is important to note that every 4 months new analytical columns, a new protective column every month and a new in-line filter must be installed.

Polystyrene polymer standards, obtained from Aldrich Chemical Co., should be mixed into a solvent consisting of dichloromethane (DCM): THF (10:90), both in HPLC purity, to obtain a 1 mg / ml concentration. Multiple polystyrene standards can be combined in one standard solution, provided that their peaks do not overlap in chromatography. A range of standards of molecular weight between about 587 to 400,000 should be prepared. Examples of standard compositions using Aldrich polystyrenes of different weight average molecular weights include: Standard 1 (401 340;

650; 2,727), Standard 2 (45,730; 4,075;

Standard 3 (95,800; 12,860) and Standard 4 (184,200; 24,150; 687).

·

A stock control standard is then prepared. Dissolve 10 g of a 200,000 molecular weight (lactic acid) standard, catalog number 19245, obtained from Polysciences Inc, in 100 ml of DCM grade HPLC in a glass jar with lid using an orbital shaker (at least 30 minutes). The mixture is poured onto a clean, dry glass plate and first allowed to evaporate the solvent, then placed in a vacuum oven preheated to 35 ° C and dried for about 14 hours under 25mm mercury pressure. Then the poles (lactic acid) are removed from the oven and the film is cut into small strips. The samples are immediately crushed using a grinding mill (with a 10 mesh sieve), taking care not to freeze the crusher by adding too much sample. Several grams of the crushed sample is stored in a dry glass container in a desiccator, while the remainder of the sample can be stored in a freezer in a container of a similar type.

It is important to prepare a new control standard before starting any new sequence of experiments and, since molecular weight is strongly influenced by sample contamination, great care should be taken in weighing and preparing. To prepare the control standard, weigh 0,0800 g ± 0,0025 g of the reference standard (lactic acid), weight average molecular weight 200 000, into a clean dry scintillation vial. Then, using a volumetric pipette or dedicated repipette, add 2 mL of DCM to the vial and tighten the cap. Allow the sample to dissolve completely. The sample is swirled in an orbital shaker such as Thermolyne Roto Mix (Type 51300) or similar device,

if necessary. To assess whether it has dissolved, the container is held at 45 at light. It is rotated slowly to see if the liquid is running down the glass. If the bottom of the container does not appear smooth, the sample is not completely dissolved. It may take several hours for the sample to dissolve. Once the sample is dissolved, 18 ml of THF is added using a volumetric pipette or dedicated repipette, the cap is tightly capped and the contents are mixed.

Sample preparation begins by weighing 0,0800 g ± 0,0025 g of sample into a clean, dry scintillation vial (great care is also required when weighing and preparing). Add 2 ml DCM with a volumetric pipette or dedicated repipette to the vial and tightly screw the vial cap. The sample is allowed to dissolve completely using the same technique as described above for the preparation of the control standard. Then 18 ml of THF is added using a volumetric pipette or dedicated repipette, the cap of the vial is tightly capped and the contents are mixed.

The evaluation is started by injecting a standard system balance control preparation. As soon as the system balance is ruptured, the standard specimen is injected. After completion of these runs, a control standard preparation and then sample preparations are injected. A control standard preparation is injected after every 7 injections of the sample and at the end of testing. Care should be taken that no more than two injections are made from one vial, and the two injections must be made 4.5 hours apart from each other.

• 9 9 9 • 9 9

There are 4 quality control parameters when evaluating the result. First, the fourth order regression correlation coefficient, calculated for each standard, should not be less than 0,950 and not more than 1,050. Second, the relative standard deviation of all weight-average molecular weights of the control standard preparations should not be greater than 5.0 percent. Third, the mean weight average molecular weight of the injections of the control standard preparations should be within 10 percent of the weight average molecular weight of the first injection of the control standard preparations. Finally, the lactide response to 200 micrograms per milliliter (gg / ml) of the standard injection is recorded on an SQC data plot. Using the graph control lines, the response must be within the defined SQC parameters.

Molecular statistics are calculated based on a calibration curve generated from polystyrene standard preparations and polystyrene THF and polystyrene THF constants at 30 ° C. These constants are: polystyrene (K = 14.1, 10 ⁵ , alpha = 0.700) and poles (lactic acid) (K = 54.9, 10 ⁵ , alpha = 0.639).

Percentage of residual lactic acid monomer

The gas chromatography (GC) method is used to analyze the lactide monomer in solid samples by poly (lactic acid). The samples must be of sufficient molecular weight to precipitate the poles (lactic acid) from a solution of methylene chloride and isopropanol.

Features include a HP5890A flame gas chromatograph with a 444 ionization detector (FID), an HP 7673A autosampler, and an HP3393A integrator. The analytical column used is Restek Tnx-5, 30 meters, 0.32 mm ID, 1.0 micron film thickness. The compressed carrier gas should have the following composition: helium, grade 4.5, hydrogen, grade zero, air, grade zero. Helium is set to 8 psig, with a linear velocity of> 20 cm per second at 100 ° C, purified by molecular sieve and OM-1 nanochrome resin trap. Injector B is set at 300 ° C, the glass liner has a cap distribution shape, deactivated with dimethyldichlorosilane, a baffle flow of 4 mL / minute and a flow rate of 70 mL / minute. Detector B (FID) is set at 305 ° C, with a hydrogen flow of 30 ml / minute, no purifier, air flow of 400 ml / minute with molecular sieve S and helium treated gas (purified from source) 25 m / minute. The test method for the furnace is as follows: The initial temperature is 100 ° C at time = 0 minutes. The first heating rate is 3 ° C / minute to 135 ° C at a final time = 3 minutes. The following section is 50 ° C / minute to 300 ° C at a final time = 5 minutes. The total run time is 22.97 minutes with 0.5 minute equilibration time. The integrator is set to a graph speed of 1.0 cm / minute, attenuation (ATTN) is 2 ³ AR rejection is set to 50. The threshold (THRSH) is -4 and the WD peak is 0.04.

Autosampler setting: INET control setting is „Yes; Inj / Bottle = 1; number of sample washes = 5; number of pumps = 5: viscosity = 1: volume = 1; number of washes with solvent A = 2: number of washes with solvent B = 2; Priority sample = 0; capillary on-column = 0

New standard solutions should be prepared weekly and stored in containers with small headroom, cooled to 4 ° C. Begin by carefully weighing 0,200 g ± 0,0100 g of the lactide reference standard on weighing paper. Transfer quantitatively to a 100 ml volumetric flask, add approximately 10 ml acetonitrile and stir. Fill the flask half with isopropanol (must have more than 150 ppm water and be in GC or other high degree of purity) and allow the solution to warm to ambient temperature to keep the inner surfaces of the flask dry.

Then

Using standards, it is diluted to a given volume of the table below with isopropanol and blended to prepare working

Concentration (gg / ml) Aliquot (ml)

1

2

100 5

200 5

400 5

1000 5

100 ml volumetric flask

100 ALIGN!

Accurately pipet a specified aliquot of the lactide stock standard into the designated volumetric flask, dilute to volume with isopropanol and mix. The gas chromatography snap-cap containers are filled up to one half and closed with a silicone rubber lid.

• · • ·

- 32 Sample preparation begins with weighing 1,000 g ± 0,0050 g of the sample with poles (lactic acid) into tared scintillation vials. Pipette 7 ml of methylene chloride into the vial and seal the cap tightly, then allow the poles (lactic acid) to dissolve completely. 14.00 mL of isopropanol is pipetted into the vial by slow addition to the vial walls. A cap is applied and the poles (lactic acid) are precipitated by vigorously shaking the vial. The vial was allowed to stand for 10 minutes to allow complete precipitation of the lactic acid, and the precipitate was allowed to sit. Next, using a syringe and a 0.45 micron GHP AcroDisc syringe filter, several ml of the supernatant is filtered into a clean scintillation vial. 2.00 ml of the filtered supernatant is pipetted into a clean and dry 10 ml volumetric flask. Dilute to volume with isopropanol and mix. Finally, using a syringe (with a 0.45 micron GHP AcroDisc syringe filter), approximately 1 mL of the diluted supernatant is filtered into a clean gas-capped snap-cap vial so that the vial is only half-filled and capped with a silicone rubber lid.

Testing is started by injecting an isopropanol empty sample. Standard preparations are then injected, using the 20 μρ / ml standard first and ending with the 2000 μρ / ml standard. Sample preparations are injected (at least 10 percent are injected in duplicate). 400 μρ / ml standards should be injected from the test vial as a control standard after injection of each duplicate sample preparation and at the end of the sequence.

• · · · · · · · · · · · · ·

Quality control parameters include:

(1) the lactide result for each injection of the control standard should be within ± 10 per cent of the true value;

(2) the correlation coefficient of linear regression, calculated for the concentration-area relationship for standard preparations, shall not be less than 0,990;

3) lactide results in duplicate injections of at least 10 percent of all sample preparations tested should be within 10 percent of each other;

4) record the lactide response to 200 micrograms per milliliter (gg / ml) of standard injection on the SQC data plot. Using the graph control lines, the response must be within the defined SQC parameters.

constructing a calibration curve to perform linear regression of the response area. Calculate the pg of the area plotted for the linear regression equation and the sample preparation using the following equation: pg of sample by poles (lactic acid) = divided by sample weight (g), ml and divided by 2 ml.

Calculations of results begin with lactide standards and concentrations relative to the analyte per ml using a straight line obtained from a steepness. Then calculate the lactide in the linear regression of residual lactide per gram μg lactide / ml in the formulation multiplied by 21 ml multiplied by 10

L: D The ratio of stereoisomers

High pressure liquid chromatography (HPLC) is used to determine the concentrations of the D-enantiomers and the L-enantiomers of lactic acid in solid poles (lactic acid), with an accuracy of · · · ·

- 34 to 0.1 percent of the D-enantiomer of lactic acid. HPLC is composed of a Chiral penicillamine analytical column and a diode array or variable wavelength detector set at 238 nanometers (nm). Water with HPLC grade grade is used in the sample preparations.

The system suitability standard is prepared by dissolving 0.2000 g (± 0.1000 g) of L-lactic acid syrup (85% aqueous solution containing approximately equal amounts of each isomer) in 100 ml of water. Further, a quality control standard is produced by dissolving 2.2000 g (± 0.1000 g) of L-lactic acid crystals supplied by Fluka Inc, over 99 percent crystalline and 0.0600 g (± 0.1000 g) of DL syrup. Lactic acid (85% aqueous solution) in a 100 ml volumetric flask.

Test samples are prepared by combining a 2.20 g (± 0.05 g) solids resin sample with 1.40 g (± 0.02 g) sodium hydroxide reagent grade (NaOH) and 5070 mL of water in a reflux flask and heating to the reflux temperature until the polymer is consumed, which usually takes about 3 hours. After completion of the reflux, the condenser was rinsed, separated and the flask allowed to cool to ambient temperature. Check the pH of the solution and adjust the pH to 4-7 with sulfuric acid (H2SO4). Transfer the treated solution to a 100 ml volumetric flask, washing the flask carefully with water and diluting with 100 ml with water and mixing.

If the sample preparation is cloudy, a portion of it is filtered through a syringe filter such as Gelman Acrodisk CR (0.45 micron PTFE) or equivalent.

The experimental procedure begins by injecting a system suitability standard to check system equilibration. The quality control standard should be injected at the beginning and end of each sequence and every five injections of the sample preparation. Once the initial phase is complete, sample preparations are injected. The system suitability standard at the end of the sequence is then injected. After analysis of all the samples, the column is washed with 0.2 to 0.5 milliliters per minute of the purification mobile phase for several hours.

Final calculations are based on peak area obtained from HPLC. Approximate retention times are: 20-24 minutes for the D isomer and 24-30 minutes for the L isomer. The resolution (R) is twice [(Rt _{L (+)} - Rt _{D (} -)) / [(Wq _{D (} _) / W _{L (+))} ], where W is the corrected peak width at baseline in minutes and Rt is retention time in minutes The number of theoretical plates (N) is 16 times (Rt / W) ^{2. The} percentage of lactic acid D is calculated as the area of the lactic acid peak D divided by the total area of the lactic acid and lactic acid peaks D then multiplied by 100.

Fiber shrinkage

The necessary thermal shrinkage equipment includes: convection oven (Thelco model 160DM laboratory oven), 0.59 (+/- 0.06 g) weight, 1/2 inch attachment clips, masking tape, graphic paper with at least 1/4 inch square, foam plate (11 by 14 inches) or equivalent substrate to attach graphical paper and samples.

• · · · · · · · · · ·

The convection oven must be capable of heating to 100 ° C.

The fiber samples are drawn from the melt under their respective processing conditions, the sliver bundle is preferred, and the samples are mechanically elongated to obtain fibers having a draw of 224 or greater. Only fibers of the same elongation can be compared to each other in appearance. The fiber throughput is the ratio of the stretching winding divided by the linear extension (distance / time) ratio of the molten polymer exiting the spinneret. The wound fiber is usually collected on the spool by means of a reel. The obtained fiber bundle is divided into 30 strands if the 30 strand bundle has not already been obtained and cut to a length of 9 inches.

The graphic paper is glued to the plate, with one edge of the paper aligned with the edge of the plate. A tape is adhered to one end of the fiber bundle, no more than beyond the 1 inch end. The stapled end is clipped to the board to the edge where the graphic paper is aligned so that the edge of the staple is in one horizontal line on the graphic paper, while keeping the fiber bundle in place (the stapled end should hardly be seen captured under the clip) . The other end of the stack is stretched and aligned parallel to the vertical lines on the graphics paper. Next, 0.5 inches of weights around the fiber bundle are fixed 7 inches below the fiber holding point. The attachment process is repeated for all samples. Usually 3 samples are attached simultaneously. Markings may be made on the graphical paper to indicate the initial positions of the weight. The samples are placed in an oven heated to 100 ° C so that they hang vertically and do not touch the plates. In time •

- At intervals of 5, 10 and 15 minutes, the new weights of the graph paper are quickly marked and the samples returned to the furnace.

After testing, the plate is removed and the distances between the origin (where the clamp retains the fibers) and the 5, 10, and 15 minute marks are measured with a scale marked 1/16 inch. Three replicates per sample are recommended. Averages, standard deviations and percent shrinkage are calculated. The shrinkage percentage is calculated as (initial length - measured length) divided by the initial length and multiplied by 100.

Examples

Various materials have been used as components for forming multi-component fibers in the following examples. The designation and various properties of these materials are given in Table 1. The apparent viscosity for many of these materials is clearly shown in Table 2.

Samples 1-6 are polymers of poly (lactic acid) obtained from Chronopol Inc, Golden, Colorado.

Polymer (lactic acid) polymer was obtained from Cargill Inc, Wayzala, Minnesota, under the designation Cargill6902 Polylactide.

Polymer (lactic acid) polymer was obtained from Aldrich Chemical Company Inc. of Milwaukee, Wisconsin, under the designation Polylaktide, catalog number 43,232-6.

Polybutylene succinate was obtained from Showa Highpolymer Co., Ltd., Tokyo, Japan under the designation Bionolle 1020.

• · • ·

39 Polybutylene succinate-co-adipate was obtained from Showa Highpolymer Co., Ltd., Tokyo, Japan under the designation Bionolle 3020.

Polyhydroxybutyrate-co-valerate Zeneca Bio-Products Inc., designated Biopol 600G.

was obtained by Wilmington, from Delaware, et al

- 40 Table 1

Designation material Ratio L: D Temperature thaw (° C) Weight medium molecular mass Numerically medium molecular mass Index polydis- persity Residual monomer acid dairy Sample 1 100: 0 175 211 000 127 000 1, 66 5, 5% Sample 2 95: 5 ~ 140 188 000 108 000 1.74 4.8% Sample 3 100: 0 175 184 000 95 000 1.94 1.5% Sample 4 95: 5 Ί40 140 000 73 000 1, 92 3.4% Sample 5 100: 0 175 181 000 115 000 1.57 2.3% Sample 6 95: 5 Ί40 166 000 102 000 1, 63 2.3% Cargill 6902 94: 5 Ί40 151 000 - - Aldrich PLA 43,232-6 94: 6 Ί40 144 000 60 000 2.4 Bionolle 1020 ON 114 - - - ON Bionolle 3020 ON 95 - - ON Biopol 600G ON 149, 161 ON

• · • ·

• · ·

Table 2

Viscosity (Pa.s) at 180 ° C

shear Sample Sample speed 6 2 (1 / sec) 50 342 114 100 ALIGN! 252.4 81 .4 200 232.1 81.4 500 153.1 70 1000 119.7 65.1 2000 87.5 52.5 5000 51.5 34.2

Viscosity (Pa.s) at 190 ° C

shear speed (1 / s) Sample 5 Sample 6 Sample 2 50 863.1 293.1 130.3 100 ALIGN! 594.4 195.4 146, 6 200 415.3 166.9 126.2 500 333, 9 127 81.4 1000 223.1 105 67.6 2000 141.1 79.8 52.9 5000 71.2 47.1 34.5

· * * * * * * * * * * * * · · · · · ·

8 · * · ··

Viscosity (Pa.s) at 195 ° C

shear speed (1 / sec) Aldrich PLA Sample 5 Sample 6 Sample 2 Cargill 6902 50 81.4 374.6 407.1 48.9 276, 9 100 ALIGN! 57 293.1 309.4 44.8 195, 4 200 48.9 256.5 276, 9 52.9 162.9 500 40.7 198.7 229, 6 51.3 123, 8 1000 36, 6 153.9 155.3 46 96.1 2000 37.8 107.9 116.4 39.3 70.8 5000 23.8 59, 9 61.2 28.8 43.2

Viscosity (Pa.s) at 200 ° C

shear speed (1 / s) Sample 5 Sample 1 Cargill 6902 50 228 1091.1 162.9 100 ALIGN! 203.6 912 122.1 200 158.8 659.5 105.9 500 136.8 400, 6 86, 3 1000 111.5 268.7 72.5 2000 87.5 153.9 56, 6 5000 51 79, 6 35.7

* «· ··« »

Table 2 (continued)

Viscosity (Pa.s)

shear rate (1 / sec) Bionolle 1020 (218 ° F) Cargill 6902 (222 ° C) 50 65, 1 16.3 100 ALIGN! 89, 6 24.4 200 97.7 24.4 500 101 27.7 1000 97.7 25.2 2000 74.9 22.8 5000 51.1 18.2

Examples 1-10

The extruders used had 3/4 inches diameter, 24: 1 (length: diameter) screws and had three heated areas. A transfer pump was used from the extruder to the extrusion section, which represented the fourth heated area. Finally, the fifth region is an extrusion section using an 18 hole spinneret (0.6 mm hole diameter) to form fibers. Temperatures in these 5 regions are listed sequentially in Table 3 under the heading "Extruder Temperatures." No finishing agent was used to prepare these multicomponent fibers. The resulting fibers were collected through a pneumatic drawing unit to form nonwoven materials. The materials used in each example, the processing conditions used and the quality of the nonwoven obtained, if any, are summarized in Table 3.

• · • ·

Table 3

Sample Polymers % train cross-section on Extrusion temperatures device (° C) Comment ♦ Example 1 Core Cargill 6902 50 177/216/221/211/207 Produces fibers, but strength Plastic # 3020 50 149/204/216/211/210 melt too low for pulling on fiber unit ♦ Example 2 Core Cargill 6902 50 149/204/216/211/207 The fibers cannot be Plastic 1020 Bionolle 50 177/216/211/211/209 attenuated as a result poor melt strength ♦ Example 3 Core Cargill 6902 / 50 182/204/216/221/217 Unable to create threads, 1020 Bionolle the melt drips from the nozzle (50:50) 50 Plastic 1020 Bionolle 149/210/216/2161214 ♦ Example 4 Core Cargill 6902 50 182/204/216/221/221 Weak melt strength a Plastic 1020 Bionolle 50 149/210/216/216/218 the fibers stick together ♦ Example 5 Core Biopol 600G 70 182/199/207/212/200 Weak melt strength. Plastic 1020 Bionolle 30 149/210/221/217/216 It generates high pressure in the extruder ♦ Example 6 Core Cargill 6902 / 50 181/208/213/219/204 Weak melt strength. Biopol 600G It generates high pressure in the (50:50) 50 extruder Plastic 1020 Bionolle 149/210/221/217/215 Example 7 Core Sample 1 60 154/199/199/199/199 Fibers based on PLA p Plastic Sample 2 40 149/185/188/188/188 achieved rheology Example 8 Core Sample 1 70 171/1991202/201/201 “A cake based on PLA p Plastic Sample 2 30 149/188/188/188/188 achieved rheology Example 9 Core Sample 1 50 170/193/193/193/199 Fibers based on PLA p Plastic Cargill 6902 50 182/195/182/182/193 achieved rheology Example 10 Core Sample 1 50 171/193/193/193/199 Fibers based on PLA p Plastic Aldrich PLA (4, 232-6) 50 182/195/182/182/193 achieved rheology

Example 11

The extruder assembly is similar to the assembly used in Examples 1-10. In this experiment, spinning nozzles 621H and a 0.6 percent aqueous solution of Chisso P finishing agent were used. The bicomponent fibers of approximately 4 denier per strand, consisting of Sample 3 as core and Sample 4 as sheath, were coiled, heat cured at 60 ° C and at 90 ° C in a dryer, shaped and then cut to staple and short cut fibers. The drawn fibers had a fiber toughness of 1.98 grams / denier and an elongation of 80 percent.

The materials used in each example, the processing conditions, the quality of the fibers obtained are summarized in Table 4.

Example 12

Bicomponent fibers with core / sheath structure were prepared with Sample 3 as the core and Sample 4 as the sheath. The extruder assembly is similar to that used in Examples 1-10 except that no transfer pump was used. Instead, the extruder was filled directly into the extrusion section. A spinneret with 288 holes (0.35 mm diameter) was used. A 12 weight percent aqueous solution of Lurol PS-6004 (Goulston Technology) was used as a finishing agent. The broaching roller was operated at a speed of 1070 meters / min and the finishing roller speed was 130 meters / minute. The resulting fiber had an elongation of 84 percent and a toughness

1.5 grams per denier for a 2.7 denier fiber. The filament was wound on a spool and then cut into short filaments 1.5 and 0.25 inches long. These fibers were then converted to a bonded carded nonwoven fabric. Materials used, processing conditions quality of obtained fibers are summarized in Table 4.

• · • ·

- 46 Table 4

Example 11 Core Plastic Sample 3 50 50 185/215/215/200/200 160/200/200/200/200 Fibers based on PLA p achieved by rheology p by temperature curing Sample 4 Example 12 Core Sample 3 50 155/200/200/200 Fibers based on PLA p achieved rheology without temperature curing Plastic Sample 4 50 115/176/185/190

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

Represented by:

Dr. Otakar Švorčik

JUDr. Otakar Švorčik attorney 120 00 Praha 2, Hálkova 2

Claims (29)

PATENT CLAIMS 1. A multicomponent fiber comprising: a. a first component having a given melting point and comprising a first polymer of poly (lactic acid) having a given L: D ratio, wherein the first component forms an exposed surface on at least a portion of the multi-component fiber; and b. a second component having a melting point that is at least about 10 ° C greater than the melting point exhibited by the first component and comprising a second polymer of poly (lactic acid) having an L: D ratio greater than the L: D ratio reported; first polymer poles (lactic acid). The multicomponent fiber of claim 1, wherein the first poly (lactic acid) polymer has an L: D ratio that is less than about 96: 4. The multicomponent fiber of claim 1, wherein the second poly (lactic acid) polymer has an L: D ratio of at least about 96: 4. The multicomponent fiber of claim 1, wherein the second poly (lactic acid) polymer has an L: D ratio that is at least about 98: 2. Multicomponent fiber according to claim 2, characterized in that the second polymer of the poly (lactic acid) has an L: D ratio which is at least about 98: 2. « 6. The multicomponent fiber of claim 1 wherein the first poly (lactic acid) polymer is present in the first component in an amount greater than about 90% by weight. 7. The multicomponent fiber of claim 1 wherein the second poly (lactic acid) polymer is present in the second component in an amount greater than about 90% by weight. The multicomponent fiber of claim 1, wherein the second component has a melting point that is at least about 20 ° C greater than the melting point exhibited by the first component. The multi-component fiber of claim 1, wherein the second component has a melting point that is at least about 25 ° C greater than the melting point exhibited by the first. component. Multicomponent fiber according to claim 1, characterized in that the first polymer of the poly (lactic acid) has a weight. a mean molecular weight ranging from about 10,000 to about 500,000. Multicomponent fiber according to claim 1, characterized in that the second polymer of the poly (lactic acid) has a weight average molecular weight that is in the range of About 10,000 to about 500,000. 12. The multi-component fiber of claim 1 wherein the first poly (lactic acid) polymer has a polydispersity index value that is in the range of about 1 to about 10. The multicomponent fiber of claim 1, wherein the second poly (lactic acid) polymer has a polydispersity index value ranging from about 1 to about 10. 14. The multicomponent fiber of claim 1 wherein the first poly (lactic acid) polymer has an L: D ratio that is less than about 96: 4, the first poly (lactic acid) polymer has a weight average molecular weight that is in the range of about 10,000 to about 500,000, the first polymer (lactic acid) polymer has a polydispersity index value that is in the range of about 1 to about 10, the first polymer (lactic acid) polymer is present in the first component in an amount that is greater than about 90% by weight, the second poly (lactic acid) polymer has an L: D ratio of at least about 98: 2, the second poly (lactic acid) polymer has a weight average molecular weight ranging from about 10 000 to about 500,000, the second poly (lactic acid) polymer has a polydispersity index value ranging from about 1 to about 10, d the polymers of lactic acid (lactic acid) are present in the second component in an amount that is greater than about 90%. · ···· ··· ··· ·· ·· ·· wt. and the second component has a melting point that is at least about 25 ° C greater than the melting point exhibited by the first component. 15. A method of manufacture and a multicomponent fiber comprising: exposing the first component to a first temperature and a first shear rate, the first component having a given first melting point, exhibiting an apparent viscosity at the first temperature and a first shear rate, and comprising a first polymer of poly (lactic acid) having a given L: D ratio; b. exposing the second component to a second temperature and a second shear rate, the second component having a melting point that is at least about 10 ° C greater than the melting point exhibited by the first component, the second component exhibiting an apparent viscosity at the second temperature and second shear rate; between the apparent viscosity of the first component and the apparent viscosity of the second component is less than about 150 Pascal, and the second component comprises a second polymer of poly (lactic acid) having an L: D ratio that is greater than the ratio of L: D exhibited by the first polymer of poly acids) and c. gluing the first component to the second component to form a multi-component fiber. The method of claim 15, wherein the first poly (lactic acid) polymer has an L: D ratio that is less than about 96: 4. 17. The method of claim 15, wherein the second poly (lactic acid) polymer has an L: D ratio of at least about 96: 4. ί The method of claim 15, wherein the second poly (lactic acid) polymer has an L: D ratio that is at least about 98: 2. 19. The method of claim 16, wherein the second poly (lactic acid) polymer has an L: D ratio of at least about 98: 2. 20. The method of claim 15, wherein the first poly (lactic acid) polymer is present in the first component in an amount greater than about 90% by weight. 21. The method of claim 15, wherein the second poly (lactic acid) polymer is present in the second component in an amount greater than about 90% by weight. The method of claim 15, wherein the second component has a melting point that is at least about 20 ° C greater than the melting point exhibited by the first component. The method of claim 15, wherein the second component has a melting point that is at least about 25 ° C greater than the melting point exhibited by the first component. 24. The method of claim 15, wherein the first 4 Polymer (lactic acid) polymer molecular weight which is 10,000 to about 500,000. has a weight median in the range of about The method of claim 15, wherein the second poly (lactic acid) polymer has a weight average molecular weight ranging from about 10,000 to about 500,000. 26. The method of claim 15, wherein the first poly (lactic acid) polymer has a polydispersity index value ranging from about 1 to about 10. The method of claim 15, wherein the second poly (lactic acid) polymer has a polydispersity index that is in the range of about 1 to about 10. 28. The method of claim 1, wherein the first poly (lactic acid) polymer has an L: D ratio that is less than about 96: 4, the first poly (lactic acid) polymer has a weight average molecular weight of ranging from about 10,000 to about 500,000, the first polymer of the (lactic acid) having a polydispersity index that is in the range of about 1 to about 10, the first polymer of the (lactic acid) present in the first component in an amount that is greater than about 90% by weight, the second polymer of the poly (lactic acid) has an L: D ratio of at least about 98: 2, the second polymer of the poly (lactic acid) has a weight average »44 4 · 4 molecular weight from about 10,000 to about 500,000, the second polymer of the poly (lactic acid) has a polydispersity index value which is in the range of from about 1 to about 10; The poly (lactic acid) polymer is present in the second component in an amount greater than about 90% by weight. and the second component has a melting point that is at least about 25 ° C greater than the melting point exhibited by the first component. The method of claim 15, wherein the difference between the apparent viscosity of the first polymer of the poly (lactic acid) and the apparent viscosity of the second polymer of the poly (lactic acid) is less than about 100 Pascal.