KR100696357B1 - Disposable Absorbent Products Containing Biodegradable Polylactide Nonwovens with Fluid Management Properties - Google Patents

Abstract

A biodegradable nonwoven and an disposable absorbent article having improved fluid handling properties. Such nonwovens can be prepared by using poly (lactic acid) polymers, polybutylene succinate polymers or polybutylene succinate adipate polymers or mixtures of these polymers, and unreacted mixtures of thermoplastic compositions comprising wetting agents. Thermoplastic compositions exhibit substantial biodegradable properties but are readily processed. Biodegradable nonwovens can be used in disposable absorbent articles intended for the absorption of fluids such as body fluids.

Biodegradable Nonwovens, Fluid Properties, Poly (Lactic Acid) Polymers, Polybutylene Succinate, Wetting Agents

Description

Disposable Absorbent Products Containing Biodegradable Polylactide Nonwovens with Fluid Management Properties}

The present invention relates to biodegradable nonwovens with improved fluid handling properties and disposable absorbent articles containing them. Nonwovens can be made from polymer blends. These blends may comprise multicomponent fibers. These multicomponent fibers include poly (lactic acid) polymers, polybutylene succinate polymers or polybutylene succinate adipate polymers or mixtures of these polymers, and unreacted mixtures of wetting agents. Multicomponent fibers are easily processed while exhibiting significant biodegradability. Disposable absorbent products can be used for the absorption of fluids such as body fluids.

Disposable absorbent products are now widely used in many fields. For example, in the field of infant and child hygiene, diapers and infant training pants have generally replaced reusable cloth absorbent articles. Other representative disposable absorbent products include feminine hygiene products such as sanitary napkins or tampons, adult incontinence products, and health hygiene products such as surgical drapes or wound dressings. Representative disposable absorbent articles generally include a composite structure comprising a surfacesheet, a backsheet, and an absorbent structure between the surfacesheet and the backsheet. These products usually include some type of fastening system for fitting the product to the wearer.

Disposable absorbent products typically accept one or more liquid feces, such as water, urine, menstruation or blood during use. Because of this, the outer cover material of the disposable absorbent article typically exhibits sufficient strength and processing capacity such that the liquid insoluble and liquid impermeability ensure that the disposable product retains its integrity and prevents the liquid excreted into the product during use by the wearer. Material, for example a polypropylene film.

Although current disposable baby diapers and other disposable absorbent products are generally accepted by the public, these products still have room for improvement in certain areas. For example, many disposable absorbent products can be difficult to dispose of. For example, attempts to flush many disposable absorbent products through a toilet and send them to a sewage system often clog the toilet or pipe connecting the toilet and the sewage system. In particular, the outer cover material conventionally used in disposable absorbent articles generally does not disintegrate or disperse when flushed down through the toilet so that the disposable absorbent article cannot be discarded in this way. If the outer cover material is made very thin in order to reduce the total volume of the disposable absorbent product to reduce the possibility of clogging the toilet or sewer pipe, the outer cover material is typically torn out when the outer cover material is subjected to normal use stress by the wearer or Or it does not exhibit sufficient strength to prevent it from popping.                 

In addition, there is a growing interest worldwide in the disposal of solid waste. As landfills continue to become full, waste disposal by means other than inflow into solid waste disposal facilities, such as reducing raw materials in disposable products, incorporating more recyclable and / or degradable components in disposable products, and landfills There is an increasing demand for designs that can be made.

Because of this, there is generally a need for new materials that retain their integrity and strength during use, but can be used in disposable absorbent articles where the material can be disposed of more efficiently after use. For example, disposable absorbent articles can be easily and efficiently disposed of by composting. Alternatively, the disposable absorbent product can be easily and efficiently disposed of into a liquid sewage system where the disposable absorbent product can be broken down.

Although degradable monocomponent fibers are known, problems have arisen in their use. In particular, known degradable fibers typically do not have good thermal dimensional stability such that the fibers generally cause severe heat shrinkage due to polymer chain relaxation during later processing such as thermal bonding or lamination.

For example, fibers made from poly (lactic acid) polymers are known, but problems have arisen in their use. In particular, poly (lactic acid) polymers have a relatively slow crystallization rate compared to, for example, polyolefin polymers and this is often known to result in poor processability of aliphatic polyester polymers. In addition, poly (lactic acid) polymers generally do not exhibit good thermal dimensional stability. Usually, poly (lactic acid) polymers cause severe heat shrinkage due to polymer chain relaxation during the later heat treatment processes such as thermal bonding or lamination, unless separate steps such as thermal curing are used. However, this thermal curing step generally limits the use of this fiber in in situ nonwoven forming processes where it is very difficult to achieve thermal curing such as spunbond and meltblown.

In addition, one of the important ingredients in many personal care products is the bodyside liner. The liner usually consists of a surfactant treated polyolefin spunbond. In spunbonds used as liners, it is preferred that the material is wettable to promote absorption of fluid excretion. In addition to rapid absorption, it is desirable for the composite absorbent product to keep the user's skin dry. It is also desirable for the spunbond material to have a soft feel to the skin. Spunbond diaper liners currently have many problems with this. First of all, the liner is made of polyolefin-based material and does not decompose. Due to the hydrophobic nature of these materials, the liner must be treated with a surfactant to make it wettable. Since the surfactant is not permanently fixed to the polyolefin, it tends to be washed during several excretion, increasing the absorption time of the nonwoven.

Thus, there is a need for nonwovens useful in wettable structures with improved fluid handling properties such as faster absorption times and improved skin dryness. Additionally, there is a need for biodegradable nonwovens that provide improved fluid handling properties.

Summary of the Invention

Accordingly, the present invention provides preferably nonwovens and disposable absorbent articles with improved fluid handling properties.

Also, non-woven and disposable absorbent articles are preferably provided with faster absorption times.

In addition, there is preferably provided a nonwoven and disposable absorbent article having improved skin dryness.

It also preferably provides biodegradable nonwovens and disposable absorbent articles while also providing improved fluid handling properties.

Also provided is a disposable absorbent article, preferably comprising a submerge material and a thermoplastic composition exhibiting desirable processability, liquid wettability, and thermal dimensional stability.

In addition, there is preferably provided a disposable absorbent article comprising a nonwoven and a thermoplastic composition that can be easily and efficiently formed into fibers.

In addition, there is preferably provided a disposable absorbent article comprising a thermoplastic composition suitable for use in making the nonwoven and the nonwoven structure.

It also preferably provides a disposable absorbent product that can be used for absorption of a fluid such as a body fluid but is readily degradable in the environment.

These desires are achieved by the present invention which provides a nonwoven comprising a thermoplastic composition that is substantially biodegradable but readily degradable in the environment.

One aspect of the present invention relates to a nonwoven fabric having a thermoplastic composition comprising a first component, a second component, and a third component.

One embodiment of such thermoplastic compositions include poly (lactic acid) polymers; Polybutylene succinate polymer or polybutylene succinate adipate polymer or mixtures of these polymers; And unreacted mixtures of poly (lactic acid) polymers, polybutylene succinate polymers or polybutylene succinate adipate polymers or wetting agents for these polymers.

In another aspect, the present invention relates to a multicomponent fiber that is substantially degradable but readily manufactured and easily processed into the desired final nonwoven structure.

One aspect of the invention is a poly (lactic acid) polymer; Polybutylene succinate polymer or polybutylene succinate adipate polymer or mixtures of these polymers; And unreacted mixtures of wetting agents to aliphatic polyester polymers and polybutylene succinate polymers or polybutylene succinate adipate polymers or mixtures of these polymers.

In another aspect, the present invention relates to a nonwoven structure comprising the multicomponent fibers disclosed herein.

One embodiment of such a nonwoven structure is a surfacesheet useful in disposable absorbent articles.

In another aspect, the present invention relates to a method for making the nonwovens disclosed herein.

In another aspect, the present invention relates to a disposable absorbent article comprising the multicomponent fibers disclosed herein.

The present invention relates to a disposable absorbent article comprising a biodegradable nonwoven and a thermoplastic composition comprising a first component, a second component, and a third component. As used herein, the term "thermoplastic" refers to a material that softens when exposed to heat and returns substantially to its original state when cooled to room temperature.

By using poly (lactic acid) polymers, polybutylene succinate polymers or polybutylene succinate adipate polymers or mixtures of these polymers, and unreacted mixtures of wetting agents, they can be substantially degraded, but the effective mechanical properties of the fibers It has been found that thermoplastic compositions can be prepared that can be easily processed into the fibers and nonwoven structures that are shown.

The first component in the thermoplastic composition is a poly (lactic acid) polymer. Poly (lactic acid) polymers are generally prepared by the polymerization of lactic acid. However, it will be appreciated by those skilled in the art that chemically equivalent materials can also be prepared by polymerization of lactide. For this reason, the term "poly (lactic acid) polymer" as used herein is intended to denote a polymer produced by the polymerization of lactic acid or lactide.

Lactic acid and lactide are known to be asymmetric molecules having two optical isomers, referred to as left-rotating (hereinafter referred to as "L") enantiomers and right-turning (hereinafter referred to as "D") enantiomers. As a result, different polymers that are chemically similar but have different properties can be prepared by polymerizing certain enantiomers or by using a mixture of two enantiomers. In particular, by changing the stereochemistry of the poly (lactic acid) polymer, for example, the melting temperature, melt rheology and crystallinity of the polymer can be controlled. By controlling these properties, it is possible to produce thermoplastic compositions and multicomponent fibers that exhibit desirable melt strength, mechanical properties, flexibility and processability to produce delicate, thermally cured and crimped fibers.

Examples of suitable poly (lactic acid) polymers for use in the present invention are Chronopol, Inc., Golden, Colorado. Various poly (lactic acid) polymers available from Chronopol, Inc.

In general, the poly (lactic acid) polymer is preferably present in the thermoplastic composition in an amount effective to produce the thermoplastic composition exhibiting desirable properties. The poly (lactic acid) polymer is greater than 0 wt% and less than 100 wt%, advantageously from about 5 wt% to about 95 wt%, suitably about 10 wt% to about 90 wt%, and more suitably about 15 wt% Present in the thermoplastic composition in an amount from about 85% by weight, wherein all weight% are poly (lactic acid) polymers, polybutylene succinate polymers or polybutylene succinate adipate polymers or these polymers present in the thermoplastic composition And a total weight of humectant. The composition ratio of the three components in the thermoplastic composition is generally important for obtaining the desirable properties of the thermoplastic composition, for example wettability, biodegradability, thermal stability and processability.

The second component of the thermoplastic composition is a polybutylene succinate polymer, a polybutylene succinate adipate polymer, or a mixture of these polymers. Polybutylene succinate polymers are generally prepared by condensation polymerization of glycols with dicarboxylic acids or acid anhydrides thereof. The polybutylene succinate polymer can be a linear polymer or a long chain branched polymer. Long-chain branched polybutylene succinate polymers are generally prepared by using additional polyfunctional components selected from the group consisting of trifunctional or tetrafunctional polyols, oxycarboxylic acids, and polybasic carboxylic acids. Polybutylene succinate polymers are known in the art and are described in European Patent Application No. 0 569 153 A2 of Showa High Polymer Co., Ltd., Tokyo, Japan. . Polybutylene succinate adipate polymers are generally prepared by polymerization of at least one alkyl glycol with at least one aliphatic polyfunctional acid. Polybutylene succinate adipate polymers are also known in the art.

Examples of polybutylene succinate polymers and polybutylene succinate adipate polymers suitable for use in the present invention are Bionole 1903 polybutylene succinate polymer (branched long chain) or Bionole 1020 polybutylene succinate. Nate polymers (essentially linear polymers) include various polybutylene succinate polymers and polybutylene succinate adipate polymers, available from Showa High Polymer Company, Limited, Tokyo, Japan under the trade name.

It is generally preferred that the polybutylene succinate polymer, polybutylene succinate adipate polymer, or mixtures of these polymers are present in the thermoplastic composition in an amount effective to produce the thermoplastic composition exhibiting the desired properties. The polybutylene succinate polymer, the polybutylene succinate adipate polymer, or a mixture of these polymers is greater than 0 wt% and less than 100 wt%, advantageously from about 5 wt% to about 95 wt%, suitably about 10 wt% % To about 90% by weight, more suitably about 15% to about 85% by weight, wherein all weight percentages are poly (lactic acid) polymers present in the thermoplastic composition; Polybutylene succinate polymer or polybutylene succinate adipate polymer or mixtures of these polymers; And the total weight of the humectant.

It is generally preferred that the poly (lactic acid) polymer and the polybutylene succinate polymer and / or the polybutylene succinate adipate polymer exhibit a weight average molecular weight that is effective to bring about the desired melt strength, fiber mechanical strength and fiber spinning properties. Do. In general, if the weight average molecular weight of a particular polymer is too high, this indicates that the polymer chains may be severely entangled resulting in a thermoplastic composition comprising a polymer that is difficult to process. Conversely, if the weight average molecular weight of a particular polymer is too low, this indicates that the polymer chains may not be entangled sufficiently enough to result in a thermoplastic composition comprising a polymer that exhibits relatively weak melt strength, making high speed processing very difficult. Thus, poly (lactic acid) polymers, polybutylene succinate polymers and / or polybutylene succinate adipate polymers suitable for use in the present invention are each advantageously from about 10,000 to about 2,000,000, more advantageously from about 50,000 to about 50,000 Weight average molecular weight of about 400,000, and suitably about 100,0000 to about 300,000. The weight average molecular weight for the polymer or polymer blend can be obtained using the method as described in the Test Methods section of this specification.

Poly (lactic acid) polymers and polybutylene succinate polymers and / or polybutylene succinate adipate polymers exhibit polydispersity index values effective to ensure that thermoplastic compositions exhibit desirable melt strength, fiber mechanical strength and fiber spinning properties. It is also preferred. As used herein, “polydispersity index” refers to a value obtained by dividing the weight average molecular weight of a polymer by the number average molecular weight of the polymer. In general, when the polydispersity index value of a particular polymer is too high, the thermoplastic composition comprising the polymer is processed due to inconsistent processing properties caused by polymer segments comprising low molecular weight polymers having lower melt strength properties during spinning. It can be difficult to do. Thus, poly (lactic acid) polymers, polybutylene succinate polymers and / or polybutylene succinate adipate polymers are advantageously about 1 to about 15, more advantageously about 1 to about 4, suitably It is preferred to exhibit a polydispersity index value of about 1 to about 3. The number average molecular weight for the polymer or polymer blend can be obtained using the method as described in the Test Methods section of this specification.

In the present invention, it is preferred that the poly (lactic acid) polymer, polybutylene succinate polymer and polybutylene succinate adipate polymer are biodegradable. As a result, the nonwovens comprising these polymers are discarded in the surrounding environment and can be substantially decomposed when exposed to air and / or water. As used herein, "biodegradable" refers to the degradation of a material from the action of naturally occurring microorganisms such as bacteria, fungi and algae.

It is also preferred in the present invention that the poly (lactic acid) polymer, polybutylene succinate polymer and polybutylene succinate adipate polymer are compostable. As a result, the nonwovens comprising these polymers are disposed of in the environment and substantially compostable when exposed to air and / or water. As used herein, “compostable” means that the material can be biodegradable at the compost site such that the material is invisibly visible and degrades into carbon dioxide, water, inorganic compounds and biomass at a rate consistent with known compostable materials. Indicates.

As used herein, the term "hydrophobic" refers to a material whose contact angle of water in air is at least 90 degrees. In contrast, the term "hydrophilic" herein refers to a material whose contact angle of water in air is less than 90 degrees. For the purpose of the contact angle can be obtained using the method as described in the Test Methods section of this specification The general subject of contact angle and its measurement is well known in the art (eg, Robert J. Good and Robert J. Stromberg, Ed., "Surface and Colloid Science-Experimental Methods", Vol. II, (Plenum Press, 1979)].

It is generally preferred that the poly (lactic acid) polymer, polybutylene succinate polymer, polybutylene succinate adipate polymer, or a mixture of these polymers are all melt processible. The polymer can therefore be about 1 gram per 10 minutes to about 600 grams per 10 minutes, suitably about 5 grams per 10 minutes to about 200 grams per 10 minutes, more suitably about 10 grams per 10 minutes to about 150 per 10 minutes It is preferable to represent the melt flow rate in grams. Melt flow rates of the materials can be obtained according to ASTM test method D1238-E, which is incorporated herein by reference.

The term "fiber" or "fibrous" as used herein refers to a material having a length to diameter ratio of the material greater than about 10. Conversely, "non-fibrous" or "non-fibrous" material refers to a material having a length to diameter ratio of about 10 or less.

When mixed separately or together, poly (lactic acid) polymers, and polybutylene succinate polymers and / or polybutylene succinate adipate polymers are generally hydrophobic. Since it is desirable to make the biodegradable nonwovens of the present invention into thermoplastic compositions that are generally hydrophilic, it has been found that it is necessary to use another component in the thermoplastic compositions of the present invention to achieve the desired properties. In addition, poly (lactic acid) polymers, and polybutylene succinate polymers and / or polybutylene succinate adipate polymers are not chemically identical and thus are somewhat immiscible with one another, adversely affecting the processing of mixtures of the polymers. Because of its ease, it has been found to improve the processability of such polymers. For example, poly (lactic acid) polymers, polybutylene succinate polymers and / or polybutylene succinate adipate polymers are sometimes difficult to mix effectively by themselves and difficult to prepare as essentially homogeneous mixtures. As such, the present invention generally relates to the use of humectants to assist in the efficient preparation of poly (lactic acid) polymers, polybutylene succinate polymers and / or polybutylene succinate adipate polymers and processing into a single thermoplastic composition. need.                 

Thus, the third component in the thermoplastic composition is a wetting agent for poly (lactic acid) polymers, and polybutylene succinate polymers and / or polybutylene succinate adipate polymers. Wetting agents suitable for use in the present invention are generally poly (lactic acid) polymers, and hydrophilic moieties that become miscible with the hydrophilic moieties of polybutylene succinate polymers or polybutylene succinate adipate polymers, and polybutylene succinate polymers. Or hydrophobic moieties that are miscible with the hydrophobic moieties of the polybutylene succinate adipate polymer. These hydrophilic and hydrophobic portions of the humectant are generally present in separate blocks so that the overall humectant structure can be diblock or random block. In general, the humectant preferably acts as a medicament to initially strengthen the bond between the plasticizer and the different polymers in order to improve the manufacture and processing of the thermoplastic composition. Next, in the nonwovens of the present invention, which are generally materials processed from thermoplastic compositions, it is preferred that the humectant acts as a surfactant by varying the contact angle of water in the air of the processed material. The hydrophobic portion of the humectant may be, but is not limited to, a polyolefin such as polyethylene or polypropylene. The hydrophilic portion of the humectant may contain ethylene oxide, ethoxylate, glycols, alcohols or any mixture thereof. Examples of suitable wetting agents are all available from petroleum light Corporation of America Oklahoma Tulsa material (Petrolite Corporation), uni-Tox ^{(UNITHOX (R))} 480 and a uni-Tox 750 ethoxylated alcohols, or uni-oxide ^{(UNICID (R))} Acid amide ethoxylates.

In general, the wetting agent preferably exhibits a weight average molecular weight that is effective for causing the thermoplastic composition to exhibit desirable melt strength, fiber mechanical strength, and fiber spinning properties. In general, when the weight average molecular weight of the humectant is too high, the humectant may not blend well with other components in the thermoplastic composition because the viscosity of the humectant becomes too high to lack the mobility required for blending. Conversely, if the weight average molecular weight of the humectant is too low, it indicates that the humectant generally cannot blend well with other components and has a viscosity low enough to cause processing problems. Accordingly, wetting agents suitable for use in the present invention advantageously exhibit a weight average molecular weight of about 1,000 to about 100,000, suitably about 1,000 to about 50,000, more suitably about 1,000 to about 10,000. The weight average molecular weight for poly (lactic acid) can be obtained using the method as described in the Test Methods section of this specification.

It is generally preferred that the wetting agent exhibits an effective hydrophilic-hodgephile balance ratio (HLB ratio). The HLB ratio of the material accounts for the relative ratio of the hydrophilicity of the material. The HLB ratio is calculated as the weight average molecular weight of the hydrophilic portion divided by the total weight average molecular weight of the material and then multiplied by 20. If the HLB ratio value is too low, the material will generally not be able to provide the desired improvement in hydrophilicity. Conversely, when the HLB ratio value is too high, the material generally cannot be blended into the thermoplastic composition due to chemical incompatibility and viscosity differences with other components. Accordingly, wetting agents useful in the present invention advantageously exhibit HLB values of about 10 to about 40, suitably about 10 to about 20, more suitably about 12 to about 16.

It is generally preferred that the humectant is present in the thermoplastic composition in an amount effective to produce the thermoplastic composition exhibiting desirable properties such as desirable heat shrinkage and preferred contact angle values. Generally, minimal amounts of humectant will be required to achieve effective blending and processing with other components in the thermoplastic composition. Generally, too much humectant will result in processing problems of the thermoplastic composition or result in a final thermoplastic composition that does not exhibit desirable properties such as advancing and retracting contact angles. Wetting agent is about 0% to about 15% by weight, advantageously about 0.5% to about 15% by weight, more advantageously about 1% to about 13% by weight, suitably about 1% to about 10% by weight %, More suitably in an amount from about 1% to about 5% by weight, wherein all weight percents are poly (lactic acid) polymers present in the thermoplastic composition; Polybutylene succinate polymers, polybutylene succinate adipate polymers or mixtures of these polymers; And the total weight of the humectant.

Although the main components of the thermoplastic composition used in the present invention have been described above, the thermoplastic composition may include other components that are not limited to these and which do not adversely affect the desirable properties of the thermoplastic composition. Examples of materials that can be used as additional components include pigments, antioxidants, stabilizers, surfactants, waxes, flow promoters, solid solvents, plasticizers, nucleating agents, particulates, and other added to improve processability of thermoplastic compositions. Includes but is not limited to materials. When the additional components are included in the thermoplastic composition, the additional components are advantageously used in an amount of less than about 10 weight percent, more advantageously less than about 5 weight percent, suitably less than about 1 weight percent. Generally preferred, wherein all weight percents are poly (lactic acid) polymers present in the thermoplastic composition; Polybutylene succinate polymers, polybutylene succinate adipate polymers or mixtures of these polymers; And the total weight of the humectant.

Thermoplastic compositions used in the present invention are generally poly (lactic acid) polymers; Polybutylene succinate polymers, polybutylene succinate adipate polymers or mixtures of these polymers; And humectants, and optionally from a mixture of any additional ingredients. In order to achieve the desired properties for the thermoplastic composition, poly (lactic acid) polymers; Polybutylene succinate polymers, polybutylene succinate adipate polymers or mixtures of these polymers; And the humectant is preferably kept substantially unreacted with each other. For this reason, poly (lactic acid) polymer; Polybutylene succinate polymers, polybutylene succinate adipate polymers or mixtures of these polymers; And each of the humectant is kept as separate components of the thermoplastic composition.

Each poly (lactic acid) polymer, and polybutylene succinate polymer, polybutylene succinate adipate polymer, or mixtures of these polymers will generally form separate regions or domains within the mixture prepared to form the thermoplastic composition. . However, depending on the relative amounts used of each of the poly (lactic acid) polymers, and polybutylene succinate polymers, polybutylene succinate adipate polymers, or mixtures of these polymers, essentially the continuous phase is present in the thermoplastic composition in relatively large amounts. It can be formed from a polymer. In contrast, polymers present in relatively small amounts in the thermoplastic composition form distinct regions or domains within the continuous phase of the more dominant polymer that substantially surrounds the less dominant polymer in the structure, thereby essentially creating a discontinuous phase. Will form. As used herein, the term "enclosed" and related terms are intended to mean that the more predominant polymer continuous phase substantially surrounds the less predominant polymer or surrounds a separate region or domain of the less predominant polymer.

In one embodiment of the thermoplastic composition or multicomponent fiber used in the present invention, the poly (lactic acid) polymer essentially forms a continuous phase, the polybutylene succinate polymer, polybutylene succinate adipate polymer, or It is preferred that the mixture forms a substantially discontinuous phase, wherein the poly (lactic acid) polymer substantially surrounds the region or domain of the polybutylene succinate polymer, polybutylene succinate adipate polymer, or mixtures of these polymers. . In such embodiments, the poly (lactic acid) polymer is present in the thermoplastic composition or the multicomponent fiber in an amount of about 75% to about 90% by weight, the polybutylene succinate polymer, the polybutylene succinate adipate polymer, or It is preferred that a mixture of these polymers is present in the thermoplastic composition or multicomponent fiber in an amount of about 5% to about 20% by weight, wherein all weight percent are present in the thermoplastic composition or multicomponent fiber in the poly (lactic acid) It is based on the total weight of the polymer, polybutylene succinate polymer or polybutylene succinate adipate polymer or mixtures of these polymers, and wetting agent.

In one embodiment of the invention, a poly (lactic acid) polymer; Polybutylene succinate polymers, polybutylene succinate adipate polymers or mixtures of these polymers; And dry mixing the humectant together to form the thermoplastic composition dry mixture, and then the thermoplastic composition dry mixture is advantageously stirred, agitated or otherwise blended to form a poly (lactic acid) polymer; Polybutylene succinate polymers, polybutylene succinate adipate polymers or mixtures of these polymers; And effectively and uniformly mixing the humectant to form an essentially homogeneous dry mixture. The dry mixture is then melt blended, for example in an extruder, to form a poly (lactic acid) polymer; Polybutylene succinate polymers, polybutylene succinate adipate polymers or mixtures of these polymers; And effectively and uniformly mixing the humectant to form an essentially homogeneous melt mixture. The essentially homogeneous melt mixture is then cooled and pelletized. Alternatively, the essentially homogeneous melt mixture can be sent directly to a spin pack or other device for forming a fiber or nonwoven structure.

An alternative method of mixing the components together is to first mix the poly (lactic acid) polymer, and the polybutylene succinate polymer, the polybutylene succinate adipate polymer, or a mixture of these polymers, and then, for example, the components together. Among the extruders used include the addition of a humectant to this mixture. It is also possible to melt mix all the components together at the same time first. Other methods of mixing the components of the invention together are also possible and will be readily apparent to those of ordinary skill in the art.

The invention also utilizes multicomponent fibers made from the thermoplastic compositions of the invention. For purposes of illustration only, the present invention is generally described in terms of multicomponent fibers comprising only three components. However, it should be understood that the scope of the present invention includes fibers having three or more components.

If the thermoplastic composition forms a multicomponent component, the exposed surface on at least a portion of the multifiber will typically be formed from the more predominant polymer present in the multicomponent fiber. Surfaces exposed on at least a portion of such multicomponent fibers generally allow for thermal bonding of the multicomponent fibers to other fibers, which may generally be the same or different from the multicomponent fibers of the present invention. As a result, multicomponent fibers can be used to form thermally bonded fibrous nonwoven structures such as nonwoven webs.

Typical conditions for thermally processing the various components are advantageously from about 100 seconds ^-1 to about 50000 seconds ^-1 , more advantageously from about 500 seconds ^-1 to about 5000 seconds ^-1 , suitably about 1000 seconds ^-1 To a shear rate of from about 3000 seconds ⁻¹ , most suitably about 1000 seconds ⁻¹ . Typical conditions for the thermal processing of the components are also advantageously using temperatures of about 100 ° C. to about 500 ° C., more advantageously about 125 ° C. to about 300 ° C., and suitably about 150 ° C. to about 250 ° C. It includes.

Methods of making multicomponent fibers are well known and need not be described in detail herein. Melt spinning of polymers involves the production of structures of continuous filaments, such as spunbond or meltblown, and discontinuous filaments, such as staples and short-cut fibers. To produce spunbond or meltblown fibers, the thermoplastic composition is generally extruded and fed to a dispensing system, where the thermoplastic composition is introduced into the spinneret plate. The spun fibers are then cooled, solidified and drawn into an aerodynamic system to form conventional nonwovens. On the other hand, rather than forming directly into a nonwoven structure, in order to produce shot or staple fibers, the spun fibers are cooled, solidified, drawn and collected to intermediate filament diameters, generally with a mechanical roll system. The fibers are then "cold stretched" to the desired final fiber diameter at temperatures below their softening temperature, crimped or shaped and cut to the desired fiber diameter.

The cooling process to the ambient temperature of the extruded thermoplastic composition is usually accomplished by blowing air below ambient temperature or below ambient temperature over the extruded thermoplastic composition. The temperature change can be referred to as quenching or subcooling because it is generally greater than 100 ° C. and most commonly greater than 150 ° C. over a relatively short time frame, for example a few seconds.

Multicomponent fibers may be cut into staple fibers having a relatively short length, for example, generally in the range of about 25 to about 50 millimeters, and shot fibers having a shorter length and generally less than about 18 millimeters. See, for example, US Pat. No. 4,789,592 to Tanigchi et al. And US Pat. No. 5,336,552 to Strack et al., Which are incorporated herein by reference.

It is preferable that the obtained multicomponent fiber exhibits an improvement in hydrophilicity which is evident by a decrease in the contact angle of water in the air. The contact angle of water in the air of the fiber sample can be measured as a forward or backward contact angle value because of the nature of the test method. Advancing contact angles generally measure the initial response of a material to a liquid, such as water. The receding contact angle generally provides a measure of how the material will perform over the period of first excretion or exposure to the liquid, as well as during subsequent excretion. Lower retracting contact angles mean that the material becomes more hydrophilic during liquid exposure, and then generally becomes able to transport the liquid more consistently. Forward and receding contact angle data can be used to confirm the very hydrophilic nature of the multicomponent fiber.

Thus, in one embodiment of the present invention, the multicomponent fiber is advantageously less than about 80 degrees, more advantageously less than about 75 degrees, suitably less than about 70 degrees, more suitably less than about 60 degrees, most suitable Preferably it represents a forward contact angle value of less than about 50 degrees, wherein the forward contact angle is measured by the method described in the Test Methods section of this specification.

In another embodiment of the present invention, the multicomponent fiber is advantageously less than about 60 degrees, more advantageously less than about 55 degrees, suitably less than about 50 degrees, more suitably less than about 45 degrees, most suitably Preferably represents a retracted contact angle value of less than 40 degrees, wherein the retracted contact angle is measured by the method described in the Test Methods section of this specification.

In another embodiment of the present invention, it is desirable that the difference be small so as to be the difference between the advancing contact angle value and the receding contact angle commonly known as contact angle hysteresis. As such, the multicomponent fiber advantageously determines the difference between the advancing contact angle value and the receding contact angle of less than about 30 degrees, more advantageously less than about 25 degrees, suitably less than about 20 degrees, more suitably less than about 10 degrees. It is preferable to indicate.

Typical poly (lactic acid) polymer materials are often heat shrinked during thermal processing later in the process. Heat shrinkage occurs mainly due to the heat induced chain relaxation of the polymer segments in the amorphous and incomplete crystalline phases. In order to overcome this problem, it is generally desirable to maximize the crystallization of the poly (lactic acid) polymer material prior to the bonding step so that the thermal energy directly melts, rather than enabling chain relaxation and reordering of the incomplete crystalline structure. A typical solution to this problem is to apply a heat cure treatment to the material. Because of this, when the produced material, for example the fiber, reaches the bonding roll and is heat cured, the fiber is substantially oriented completely or very much so that it does not substantially shrink. The present invention eliminates the need for this additional processing step because of the morphology of the multicomponent fiber. In general, the addition of polybutylene succinate polymers, polybutylene succinate adipate polymers, or mixtures of these polymers, and wetting agents reduces the thermal shrinkage of multicomponent fibers compared to fibers made only of poly (lactic acid) polymers. .

In one embodiment of the invention, the nonwoven fabric is advantageously less than about 15%, more advantageously less than about 10%, suitably less than about 5% when quantified by a heat shrink value at a temperature of about 90 ° C. It is preferred to use a thermoplastic composition or multicomponent fiber, wherein the amount of shrinkage is based on the difference between the initial and final lengths of the fiber divided by the initial length and then multiplied by 100. The method for obtaining the heat shrinkage amount indicated by the fiber is included in the test method part of the present specification.

In one embodiment of the present invention, since the shrinkage of the multicomponent fibers causes the nonwoven structure to exhibit three-dimensional topography, the multicomponent fibers exhibit a shrinkage of less than about 5% suitably at a temperature of about 90 ° C. It is desirable to result in nonwoven structures formed from multicomponent components that exhibit a quilting or waviness effect of increasing surface area. This quilted or wavy effect of the nonwoven structure has been found to improve the flexibility and z-direction transport of the liquid in the nonwoven structure.

It is also generally desirable for the multicomponent fiber to exhibit desirable mechanical strength properties such as breaking stress and modulus values to maintain its integrity when using nonwovens. In one embodiment of the present invention, it is preferred that multicomponent fibers made from the thermoplastic compositions described above have improved modulus values as well as improved break stress values as compared to fibers made from poly (lactic acid) polymers alone. In one embodiment of the invention, it is preferred that the multicomponent fiber also exhibits a break stress value that is at least two times the break stress value exhibited by other identical fibers made alone from the poly (lactic acid) polymer used to make the multicomponent fiber. Do.

In one embodiment of the invention, it is preferred that the multicomponent fiber exhibits a breaking stress value of greater than about 10 MPa, advantageously greater than about 15 MPa, suitably greater than about 20 MPa, and less than or equal to about 100 MPa.

In another embodiment of the present invention, it is preferred that the multicomponent fibers exhibit a coefficient value of less than about 150 MPa, advantageously less than about 125 MPa, suitably less than about 100 MPa.

The biodegradable nonwovens of the present invention may be used in disposable absorbent articles such as diapers, adult incontinence products and bed pads; Menstrual devices such as sanitary napkins and tampons; And other absorbent products, such as wipes, bibs, wound dressings and disposable products including surgical capes or drapes. Thus, in another aspect, the present invention relates to a disposable absorbent article comprising the multicomponent fiber described above.

In one embodiment of the invention, the multicomponent fibers are molded into a fibrous matrix for incorporation into a disposable absorbent article. The fibrous matrix may take the form of a fibrous nonwoven web, for example. Fibrous nonwoven webs can be made entirely from multicomponent fibers, or they can be blended with other fibers. The length of the fibers used may depend on the particular end use intended. If the fiber is to be degraded in water, for example in a toilet, it is advantageous to keep the length below about 15 millimeters.

In one embodiment of the present invention, a liquid permeable surface sheet, a fluid absorbent layer, an absorbent structure, and a liquid impermeable backsheet generally comprise at least one of the liquid permeable surface sheet, fluid absorbent layer, or liquid impermeable backsheet. Disposable absorbent articles are provided that include a composite structure comprising a secondary fabric of the invention. In some cases, it may be advantageous for all three of the surfacesheets, fluid absorbent layer and backsheet to comprise the nonwovens of the present invention.

In another embodiment, the disposable absorbent article generally includes a liquid permeable surface sheet, an absorbent structure, and a liquid impermeable backsheet, wherein at least one of the liquid permeable surface sheet or the liquid impermeable backsheet is formed from the nonwoven fabric of the present invention. It includes a composite structure containing.

In another embodiment of the invention, the nonwoven can be made on a spunbond line. Resin pellets comprising the thermoplastic material described above are prepared and predried. Then they are fed to a single extruder. The fibers can be stretched and thermally bonded onto the forming wires through a fiber drawing device (FDU) or an air drawing device. However, other methods and manufacturing techniques can also be used.

Exemplary disposable absorbent articles are described in US-A-4,710,187, which is incorporated herein by reference; US-A-4,762,521; US-A-4,770,656; And US-A-4,798,603.

Absorbent articles and structures according to all aspects of the present invention generally experience multiple body fluid excretion during use. Thus, the absorbent article and the structure can preferably absorb multiple feces of body fluid in an amount such that the absorbent article and the structure will be exposed during use. Excretion is generally spaced apart from one another over a period of time.                 

<Test method>

Melting temperature

The melting temperature of the material was measured using a differential scanning calorimeter. All located in New Castle, Delaware, USA. Named Thermal Analyst 2910 Differential Scanning, equipped with a Liquid Nitrogen Cooling Accessory, available from TA Instruments Inc., and used with the Thermal Analyst 2200 Analysis Software (version 8.10) program. Differential scanning calorimeter under calorimeter was used for the measurement of melting temperature.

The material samples tested were in the form of fiber or resin pellets. It is desirable not to handle the material sample directly, but rather to use tweezers and other tools to ensure that nothing is included that could be misleading. Material samples were cut for fibers or placed in aluminum pans for resin pellets and weighed with 0.01 mg accuracy on an analytical balance. If necessary, the lid was crimped over a sample of material on the pan.

Differential scanning calorimetry was calibrated using an indium metal reference, as described in the manual for differential scanning calorimetry, and baseline calibration was performed. To test the material samples, they were placed in the test chamber of a differential scanning calorimeter and an empty pan was used for reference. All tests were conducted with 55 cm ³ / min nitrogen (industrial) purge to the laboratory. The heating and cooling program begins when the laboratory equilibrates to -40 ° C, followed by a heating cycle of up to 200 ° C at 20 ° C / min, followed by a cooling cycle to -40 ° C at 20 ° C / min, and then 20 ° C / min. This is a two cycle test followed by another heating cycle up to 220 ° C. in minutes.

The results were evaluated using an analytical software program that identifies and quantifies the glass transition temperature (Tg), endothermic and exothermic peaks at the inflection point. The glass transition temperature was identified as the area on the straight line where the distinct change in slope occurred, and then the melting temperature was determined using an automatic inflection point calculation.

Apparent viscosity

All used with the WinRHEO (version 2.31) analysis software, available from the Gottfert Company, Rock Hill, SC, USA Gottfert Rheograph 2003 capillary rheometer The parent viscometer flow system was used to evaluate the apparent viscosity rheological properties of the material samples. The capillary flowmeter setup included a 2000 bar pressure transducer and a round hole capillary die of 30 mm length / 3 mm working length / 1 mm diameter / 0 mm height / 180 ° each rotation.

If the material sample being tested has been proven or known to have susceptibility, the material sample is at least 15 inches (38.1 cm) of mercury in a vacuum oven at or above its glass transition temperature, i. Dry for at least 16 hours with 30 standard cubic feet / hour nitrogen gas purge under vacuum.

Once the apparatus was warmed up and the pressure transducer was calibrated, the material samples were incrementally loaded into the column by packing the resin into the column with a ramrod every hour to allow for constant melting during the test. After the material sample load, a melt time of 2 minutes was run for each test to allow the material sample to melt completely at the test temperature. The capillary flowmeter automatically takes the data points and obtains the apparent viscosity (in Pascals per second) at seven apparent shear rates (in ^-1 units), that is, 50, 100, 200, 500, 1000, 2000, and 5000. When looking at the generated curve, it is important that the curve is relatively gentle. If there is a significant deviation from the general curve from one point to another, possibly due to air in the column, the test shall be repeated until the results are reconfirmed.

The resulting rheological curves of apparent shear rate versus apparent viscosity show how the material sample flows at that temperature during the extrusion process. Apparent viscosity values at shear rates above 1000 sec ⁻¹ are of particular interest because they are representative conditions found in commercial fiber spinning extruders.

Molecular Weight

Gas permeation chromatography (GPC) methods are used to determine the molecular weight distribution of a sample, such as, for example, poly (lactic acid) having a weight average molecular weight (M _w ) of about 800 to about 400,000.

GPC was set up in series with two PL gel mixed K linear 5 micron, 7.5 × 300 mm analysis columns. Column and detector temperatures are 30 ° C. The mobile phase is high performance liquid chromatography (HPLC) grade tetrahydrofuran (THF). The pump speed is 0.8 milliliters per minute at an injection volume of 25 microliters. The total driving time is 30 minutes. It is important to note that new analysis columns should be installed approximately every four months, new guide columns approximately monthly, and new inline filters approximately monthly.

Standards of polystyrene polymers obtained from Aldrich Chemical Co. must be mixed into a solvent of all HPLC grade dichloromethane (DCM): THF (10:90) to obtain a 1 mg / mL concentration. Multiple polystyrene standards can be mixed in one standard solution provided so that their peaks do not overlap when chromatographed. Standards in the range of about 687 to 400,000 molecular weight should be prepared. Examples of Aldrich polystyrene and standard mixtures of various weight average molecular weights are 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). It includes.

A check standard mother liquor is then prepared. 10 g of a 200,000 molecular weight poly (lactic acid) standard, Catalog # 19245, obtained from Polysciences, Inc., was dissolved in 100 ml of HPLC grade DCM and lined with an orbital shaker (more than 30 minutes) Placed into a glass container. The mixture was poured onto a clear, dry glass plate, first allowing the solvent to evaporate and then placed in a preheated vacuum oven at 35 ° C. and dried under vacuum of 25 mm mercury for 14 hours. The poly (lactic acid) was then removed from the oven and the film was cut into small strips. The sample was immediately milled using a grinding mill (with a 10 mesh screen), taking care not to add too much sample to stop the mill. Several grams of the ground sample can be stored in a dry glass container in a desiccator, while the remaining samples can be stored in a freezer in a similar type of container.

It is important to prepare a new check standard before the start of each new sequence, and pay close attention to its weighing and preparation because the molecular weight is greatly influenced by the sample concentration. To prepare a check standard, 0.0800 g ± 0.0025 g of a poly (lactic acid) reference standard of 200,000 weight average molecular weight was weighed into a clear dry scintillation vial. Then, using a volumetric pipette or dedicated pipette, 2 ml of DCM was added to the vial and the cap was screwed tight. The sample was allowed to dissolve completely. If necessary, the samples were swirled on an orbital shaker, such as Thermomolyne Roto Mix (type 51300) or similar mixer. To see if it was dissolved, the vial was held up towards the bulb at a 45 ° angle. It was slowly rotated to observe the liquid as it flowed down the glass. If the bottom of the vial did not appear smooth, the sample did not dissolve completely. It may take several hours for the sample to dissolve. Once dissolved, 18 ml of THF was added using a volumetric pipette or dedicated pipette and the vial was tightly capped and mixed.

Sample preparation is initiated by weighing 0.0800 g ± 0.0025 g of sample into a transparent dry scintillation vial (a great deal of attention must also be paid to weighing and preparation). 2 ml of DCM was added to the vial by a volume pipette or dedicated pipette and the cap was screwed tight. Samples were allowed to dissolve completely using the same techniques as described for the check standard preparation described above. 18 ml THF was then added using a volumetric pipette or dedicated pipette and the vial was tightly capped and mixed.

The evaluation was started by equilibrating the test injection of the standard formulation into the test system. Once equilibrium was confirmed, standard formulations were injected. After running them, the check standard preparation was first injected followed by the sample preparation. Check standard formulations were injected after every 7 sample injections and at the end of the test. No more than two injections from any one vial should be made, and these two injections should be made within 4.5 hours of each other.

There are four quality control parameters to evaluate the results. First, the correlation coefficient of the fourth order regression calculated for each standard should be at least 0.950 and at most 1.050. Second, the relative standard deviation of all weight average molecular weights of the check standard formulation should be 5.0% or less. Third, the average of the weight average molecular weight of the check standard formulation injection should be within 10% of the weight average molecular weight for the first check standard formulation injection. Finally, the lactide response for 200 micrograms (μg / mL) per microliter of standard injection was recorded on the SQC data chart. Using the control line of the chart, the response should be within the defined SQC parameters.

Molecular statics were calculated based on calibration curves generated from polystyrene standard formulations and constants for polystyrene and poly (lactic acid) at 30 ° C. in THF. These are polystyrene (K = 14.1 * 10 ⁵ , alpha = 0.700) and poly (lactic acid) (K = 54.9 * 10 ⁵ , alpha = 0.639).

Heat shrink of fiber

The apparatus required for the measurement of heat shrinkage is a convection oven [Precision & Scientific Inc., Chicago, Illinois. Thelco Model 160DM Laboratory Oven, available from Precision and Scientific Inc., 0.5 g (+/- 0.06 g) sinker weight, 1/2 inch (1.27 cm) mating clip, masking tape , Graph paper having at least 1/4 inch ² (1.61 cm ² ), foamed posterboard (11 × 14 inches (27.94 × 35.56 cm), or equivalent support for attaching the graph paper to the sample. The convection oven should be able to reach temperatures of about 100 ° C.

Fiber samples were melt spun at their respective spinning conditions. In general, 30 filament bundles are preferred, and mechanically stretched to yield fibers having a jetstretch ratio advantageously of 224 or more. Only fibers having the same jet draw ratio can be compared with each other in terms of their heat shrink. The jet draw ratio of the fiber is the ratio of the speed of the draw roll divided by the linear extrusion rate (distance / time) of the molten polymer exiting the spinneret. The spun fibers were generally collected onto bobbins using a winder. The collected fiber bundles were separated into 30 filaments if 30 filament bundles were not already obtained and cut into 9 inch (22.86 cm) lengths.

The graph paper was taped onto the posterboard so that one edge of the graph paper coincided with the edge of the posterboard. One end of the fiber bundle was taped so that the end was not 1 inch (2.54 cm). The taped end was clipped to the posterboard at the edge where the graph paper was aligned so that the fiber bundle was held in place while the end of the clip was on one of the horizontal lines on the graph paper (when the taped end was held under the clip). Hardly visible). The other end of the bundle was pulled and aligned in parallel with the vertical line on the graph paper. A 0.5 g sinker was then inserted around the fiber bundle, 7 inches (17.78 cm) below the point where the clip was binding the fibers. The attachment process was repeated for each repeated test piece. In general, three replicate specimens may be attached at one time. Markers indicating the initial position of the sinker were displayed on the graph paper. The sample was placed in an oven at a temperature of about 100 ° C. to prevent the samples from hanging vertically and in contact with the posterboard. At time intervals of 5, 10 and 15 minutes, the new position of the sinker was quickly marked on the graph paper and the sample was returned to the oven.

After the test was completed, the posterboard was removed, and the distance between the circle (where the clip held the fiber) and the marker at 5, 10 and 15 minutes was measured with 1/16 inch (0.15875 cm). Measured. Three replicate specimens per sample are recommended. Mean, standard deviation and shrinkage were calculated. Contraction was calculated by dividing (initial length-measured length) by the initial length and multiplying by 100. As reported in the Examples herein and used throughout the claims, the heat shrink value is the amount of heat shrink that the fiber sample exhibits for about 15 minutes at a temperature of about 90 ° C., as measured according to the test method described above. Indicates.

Contact angle

All devices are Arti-Kan Instruments, Inc., Madison, WI. DCA-322 dynamic contact angle analyzer and WinDCA (version 1.02) software available from ATI-CAHN Instruments, Inc. The test was performed on an "A" loop with a balance stirrup attached. Calibration should be done monthly for the motor and daily for the scale (100 mg weight used) as indicated in the manual.

The thermoplastic composition was spun into fibers and the contact angle was measured using a free drop sample (jet stretch 0). Care should be taken during fiber manufacture to minimize the fiber exposed to handling to keep contamination to a minimum. The fiber sample was attached to a wire hanger with Scotch tape to allow 2-3 cm of the fiber to extend past the end of the hanger. The fiber sample was then cut with a razor blade so that 1.5 cm extended past the end of the hanger. The average diameter (measured three to four times) was measured along the fiber using an optical microscope.

The sample on the wire hanger was suspended from the balance reinforcement rod on the loop "A". The immersion liquid was distilled water and exchanged for each test sample. The test was started with test sample parameters (ie fiber diameter). The step was run at 151.75 microns / second until zero immersion depth was detected when the fiber was in contact with the distilled water surface. From the immersion depth of zero, the fibers were advanced into water by 1 cm, allowed to stay for 0 seconds and then immediately retracted 1 cm. Automatic analysis of the contact angles performed by the software measures the advancing and retracting contact angles of the fiber samples based on the standard calculation methods presented in the manual. A contact angle of zero or <0 means that the sample is fully wettable. Five replicate specimens were tested for each sample to calculate statistical analysis of mean, standard deviation, and coefficient of change. As reported in the Examples herein and used throughout the claims, the forward contact angle value represents the forward contact angle of distilled water on a fiber sample as measured according to the test method described above. Similarly, as reported in the Examples herein and used throughout the claims, the receding contact angle value represents the receding contact angle of distilled water on a fiber sample as measured according to the test method described above.

Fluid Absorption and Backflow Assessment (FIFE)

The fluid uptake and backflow assessment (FIFE) test was used to measure the uptake time and backflow of the personal care product. The Master-Flex Digi-Staltic automatic metering system is supplied with a small amount of saline, colored with a small amount of FD & C blue dye, and set to provide 80 mL droppings to remove any air bubbles. Discharged. A product sample, an infant hygiene diaper, was prepared without elasticity so that the diaper could easily be laid flat. Two 3.5 inch (8.89 cm) x 12 inch (30.48 cm) blotterage samples were weighed. These papers were placed on a FIFE plate, a simple plate with a 3 inch (7.62 cm) x 6 inch (15.24 cm) raised platform in the center. The blotters were aligned so that they were longitudinal along one side of the raised platform. The diaper is then aligned so that the carefully wetted area is centered on the raised platform, with the surface sheet facing up so that there is no visible wrinkle on the nonwoven surface sheet. The second FIFE plate was then placed on top of the article. The device consists of a flat plate intersecting a hollow cylinder which projects only from the top surface of the plate. The circular area created where the cylinder crossed the flat side of the plate was hollow. The inner diameter of the cylinder was 5.1 centimeters. A funnel with an internal diameter of 7 millimeters at the short end was placed in the cylinder. The pump was then placed directly in the funnel to drain the fluid. Absorption time was recorded as a stopwatch from the time the fluid hits the funnel to the moment when no fluid is visible on the test specimen surface. The blotter paper was checked for product leakage, and if the leak occurred, the weight of the blotter paper was measured to determine the amount of the leaked fluid. In the above test, no leakage occurred. After approximately one minute elapsed, the second excretion was applied in the same manner. Again in the same way the third excretion was applied at the same time interval. If necessary, one method was then used to determine the amount of fluid that flowed back when the product was under pressure. In this case only the rate of absorption was recorded.

Water loss through the epidermis (TEWL)

Changes in skin hydration as a result of product use were measured using a TEWL armband test through the epidermis. As measured by a Servo Med Evaporimeter, lower evaporation values refer to products that promote dry skin. This test actually records the change in evaporation value. The moisture evaporation rate was measured before and immediately after the test. The difference in these values gives the TEWL value as reported in the results. Lower TEWL values suggest that the product provides better breathability to the skin.

In this case, the product, an infant hygiene diaper, was made by hand without any elastic material or ear. The basic structure of the diaper was the same, but one control diaper consisted entirely of standard material, the rest all had standard material except the surface sheet, wherein the surface sheet was made of biodegradable nonwoven fabric. Target areas for excretion were absorbed in permanent markers outside the product. All tests were conducted in a controlled environment of 72 ± 4F with a relative humidity of 40 ± 5%. Subjects were adult women carefully chosen to have no conditions that could potentially change the test results.

The subjects were allowed to rest in a controlled environment until a stable reference reading of less than 10 g ² / m / hour was obtained with a servo med evaporator. These measurements were performed inside the upper arm of the subject. A Masterflex Digi-Static Batch / Dispensing Pump was used with the silicone tube in the pump head, which was connected to the neoprene discharge line for evacuation by barb fitting. The end of the neoprene discharge tube was placed on the upper arm of the test subject and the product was attached to the upper arm so that the target excretion area was directly on top of the tube opening. The product was secured with tape that wraps around the diaper but does not come in contact with the skin. The diaper was then loaded with excrement of 60 mL of saline three times at 45 second intervals and the tube removed. The product was further secured with an elastic net and the subject was allowed to sit for 1 hour. After 60 minutes of wearing, the product was removed and second readings were taken for 2 minutes in the same upper arm region where the reference reading was obtained using an evaporator. The result recorded is the difference between the reference reading and one hour.

Thermoplastic compositions and multicomponent fibers were prepared in the following examples using various materials as ingredients. The trade names and various properties of these materials are listed in Table 1 below.

Heplon A10005 poly (lactic acid) (PLA) polymer was obtained from Chronopol Inc., Golden, Colorado.

Polybutylene succinate (PBS), available under the trade name Bionole 1202 polybutylene succinate, was obtained from Showa High Polymer Company, Limited, Tokyo, Japan.

Polybutylene succinate with branched long chains (PBS), available under the trade name Bionole 1903 Polybutylene Succinate from Showa High Polymer Company, Limited, Tokyo, Japan.

The wetting agents used in the examples obtained under the trade name Unitox 480 ethoxylated alcohol from Petrolite Corporation, Tulsa, Oklahoma, exhibiting a number average molecular weight of about 2250, an ethoxylate percentage of about 80 weight percent, and an HLB value of about 16.

Trade name of the material L: D ratio Melting point (℃) Weight average molecular weight Number average molecular weight Polydispersity index Residual Lactic Acid Monomer PLA sample 1 100: 0 175 187,000 118,000 1.58 <1% PLA sample 2 95: 5 140-145 190,000 108,000 1.76 <3% Bionole 1020 N / A 95 40,000 to 1,000,000 20,000 to 300,000 ~ 2 to ~ 3.3 N / A Bionole 1903 N / A 120 40,000 to 1,000,000 20,000 to 300,000 ~ 2 to ~ 3.3 N / A

<Examples 1 to 5>

Thermoplastic compositions were prepared using various amounts of poly (lactic acid) polymer, polybutylene succinate and wetting agents. To prepare the particular thermoplastic composition, the various components were first dry mixed and then melt blended in oppositely rotating biaxial screws to mix the components vigorously. Melt mixing involves partial or complete melting of the components combined with the shear effect of rotating mixing screws. These conditions contribute to the optimal blending and even dispersion of the components of the thermoplastic composition. Twin-screw extruders, for example, Haake Rheocord 90 available from Haake GmbH, Kaalsauthe, Germany, or Vaven Instruments, South Haecken, NJ, USA. Barbender twin screw mixers (cat no 05-96-000) or other comparable twin screw extruders available from Barbender Instruments are well suited for this task. After extrusion from the melt mixer, the molten composition was cooled by a forced atmosphere on a liquid cooled roll or surface and / or through an extrudate. The cooled composition was then pelletized for conversion to fibers.

The conversion of these resins into fibers was carried out on an extruder by running on a 0.7: 1 inch (1.905 cm) diameter in-hause extruder with a 24: 1 L: D (length: diameter) non-screw and three heating zones. Koch ^(R ) SMX type of 0.62 inch (approximately 1.6 cm) diameter constructing a fourth heating zone and available from Koch Engineering Company, Inc., New York, NY Feed through a conduit to a spin pack containing a static mixer device and then through a spin plate, a simple plate with numerous small holes through which a spinning head (fifth heating zone) is fed and the molten polymer is extruded through it. Let's do it. As used herein, the spin plate has 15 to 30 holes, with each hole having a diameter of about 20 mils. The fibers are quenched with air in the temperature range of 13 ° C. to 22 ° C., drawn down by a mechanical draw roll, passed through a winder device for collection or with a fiber drawing device for spunbond formation and bonding. It may be passed through an auxiliary device for thermal curing or other treatment prior to movement or collection.

The polymer was converted to spunbond nonwoven materials using 14 "and 20" fiber spinning lines. Single component fibers were prepared from a single extruder and the fibers were drawn and passed through a fiber drawing unit (FDU). The web was then thermally inline bonded in a wire-weave bonding pattern.

The wettability of nonwoven examples was quantified using contact angle measurements, suggesting that the lower the contact angle, the more wettable the material. Contact angle measurements were performed on a Kahn DCA-322 dynamic contact angle analyzer using WinDCA (version 1.02) analysis software. The resin was stretched into free-fall fibers for use in this measurement. Further care was taken to avoid handling the sample badly to help prevent contamination in the samples. A single fiber of about 3 cm length was attached to the thin wire hanger with a tape extending 1.5 cm past the end of the hanger. Fiber diameters were measured using an optical microscope and recorded on a computer. Other parameters such as fiber shape and surface tension of the liquid to be used were also recorded in the software. In this example, distilled water was used as the liquid.

The fibers were hung on an "A" loop balance and a small beaker with water was placed underneath so that the ends of the fibers were almost in contact with the surface of the liquid. The step was maintained by advancing the fiber at 151.75 microns / second until the fiber found zero immersion depth (ZDOI) when it contacted the surface of distilled water. From ZDOI, the fibers were advanced 1 cm, allowed to stay for 0 seconds and immediately retracted 1 cm. Data analysis was performed automatically by analysis software. Each sample was tested five times and the mean value was calculated for both the forward and backward contact angles.

The results for the forward and backward contact angles are shown in Table 2 below. The forward contact angle is a measure of how the material interacts with the fluid when it first contacts the liquid. The receding contact angle indicates how the material will behave during moist liquid excretion and also in damp and high humidity environments. Blends included in the present invention produced highly wettable fibers.

Contact angle data material Advancing contact angle Retraction contact angle PLA: PBS: Unitox (78: 9: 13) 71 44 PLA: PBS: Unitox (86: 9: 5) 73 44 PLA: PBS: Unitox (87: 10: 3) 77 49 PLA: PBS: Unitox (89: 10: 1) 79 55 Polypropylene 128 94

Table 3 shows the results for the fluid treatment properties of the nonwovens of the present invention. As demonstrated in the table, the nonwovens of the present invention have a much faster absorption time than the control treated polypropylene spunbond liner. Upon subsequent excretion, the deactivation agent began to wash off the treated diaper liner with a significant increase in absorption time. The permanent hydrophilic surfaces of the nonwovens of the present invention remain permanently wettable, thus increasing the absorption time but having a much lower absorption time than polypropylene liners. In addition, liners made using the nonwovens of the present invention also exhibit lower backflow than control liners. This low backflow is significant because it indicates that there is little fluid flowing back to the user side of the liner under pressure, keeping the skin more dry.

One of the most significant tests for skin drying is how the materials behave in the TEWL test, which measures the dryness of skin covered with a saline-drained diaper. Low TEWL values indicate that the nonwovens of the present invention improve skin dryness.

Fluid handling characteristics Control-0.5 osy polypropylene spunbond 0.8 osy PLA / PP / Unitox blend FIFE-1st excretion time (seconds) 28.03 22.68 FIFE-2nd excretion time (seconds) 83.03 54.08 FIFE-3rd excretion time (seconds) 94.98 55.95 Reflux (grams) 3.40 1.99 Dry skin-TEWL (g / m ² ) 22.1 19.1

Those skilled in the art will appreciate that many modifications and variations can be made in the present invention without departing from its scope. Accordingly, the foregoing detailed description and examples are illustrative only and are not intended to limit the scope of the invention as described in the appended claims in any way.

Claims (37)

A biodegradable nonwoven comprising a liquid permeable surfacesheet, a fluid absorbent layer, an absorbent structure and a liquid impermeable backsheet, and at least one of the liquid permeable surfacesheet, fluid absorbent layer, or liquid impermeable backsheet comprises a thermoplastic composition of a plurality of fibers. To include, the thermoplastic composition is a. Poly (lactic acid) polymer in an amount greater than 0 and less than 100% by weight, b. A polymer selected from the group consisting of polybutylene succinate polymers, polybutylene succinate adipate polymers, and mixtures of these polymers in an amount greater than 0 and less than 100% by weight, and c. A wetting agent exhibiting a hydrophilic-hodgephilic balance ratio of 10-40, in an amount greater than 0 to 15% by weight, All of these weight percents are poly (lactic acid) polymers present in the thermoplastic composition; A polymer selected from the group consisting of polybutylene succinate polymers, polybutylene succinate adipate polymers, and mixtures of these polymers; And based on the total weight of the humectant. The poly (lactic acid) polymer of claim 1, wherein the poly (lactic acid) polymer is present in an amount from 5% to 95% by weight and is selected from the group consisting of polybutylene succinate polymer, polybutylene succinate adipate polymer, and mixtures of these polymers. Wherein the selected polymer is present in an amount of 5% to 95% by weight and the humectant is present in an amount of 0.5% to 15% by weight. 3. The poly (lactic acid) polymer according to claim 2, wherein the poly (lactic acid) polymer is present in an amount of 10% to 90% by weight and is selected from the group consisting of polybutylene succinate polymer, polybutylene succinate adipate polymer, and mixtures of these polymers. Wherein the selected polymer is present in an amount of 10% to 90% by weight and the humectant is present in an amount of 1% to 13% by weight. The disposable absorbent article of claim 1 wherein the humectant exhibits a hydrophilic-hodgephile balance ratio of 10-20. The disposable absorbent article of claim 1 wherein the humectant is an ethoxylated alcohol. The poly (lactic acid) polymer of claim 1, wherein the poly (lactic acid) polymer is present in an amount of 75% to 90% by weight and is selected from the group consisting of polybutylene succinate polymer, polybutylene succinate adipate polymer, and mixtures of these polymers. Disposable absorbent article wherein the selected polymer is present in an amount from 5% to 20% by weight and the humectant is an ethoxylated alcohol. A liquid permeable surfacesheet, a fluid absorbent layer, an absorbent structure, and a liquid impermeable backsheet, wherein at least one of the liquid permeable surfacesheet, fluid absorbent layer, or liquid impermeable backsheet is made from a thermoplastic composition and has a forward contact angle value of 0 to 80 degrees and Wherein the thermoplastic composition comprises a biodegradable nonwoven comprising a plurality of multicomponent fibers exhibiting a retracting contact angle value of 0 to 60 degrees. a. Poly (lactic acid) polymer in an amount greater than 0 and less than 100% by weight, b. A polymer selected from the group consisting of polybutylene succinate polymers, polybutylene succinate adipate polymers, and mixtures of these polymers in an amount greater than 0 and less than 100% by weight, and c. A wetting agent exhibiting a hydrophilic-hodgephilic balance ratio of 10-40, in an amount greater than 0 to 15% by weight, All of these weight percents are poly (lactic acid) polymers present in the thermoplastic composition; A polymer selected from the group consisting of polybutylene succinate polymers, polybutylene succinate adipate polymers, and mixtures of these polymers; And based on the total weight of the humectant. 8. The poly (lactic acid) polymer of claim 7, wherein the poly (lactic acid) polymer is present in an amount from 5% to 95% by weight and is selected from the group consisting of polybutylene succinate polymer, polybutylene succinate adipate polymer, and mixtures of these polymers. Wherein the selected polymer is present in an amount of 5% to 95% by weight and the humectant is present in an amount of 0.5% to 15% by weight. The disposable absorbent article of claim 7 wherein the humectant exhibits a hydrophilic-hodgeotic balance ratio of 10-20. The disposable absorbent article of claim 7 wherein the humectant is an ethoxylated alcohol. 8. The disposable absorbent article of claim 7 wherein the multicomponent fiber exhibits a forward contact angle value of 0 to 75 degrees and a retracted contact angle value of 0 to 55 degrees. 12. The disposable absorbent article of claim 11 wherein the difference between the forward and backward contact angle values is between 0 and 30 degrees. 8. The disposable absorbent article of claim 7 wherein the multicomponent fiber exhibits a heat shrinkage value of 0-15%. The poly (lactic acid) polymer of claim 7, wherein the poly (lactic acid) polymer is present in an amount of 75% to 90% by weight and is selected from the group consisting of polybutylene succinate polymer, polybutylene succinate adipate polymer, and mixtures of these polymers. The selected polymer is present in an amount of 5% to 20% by weight, the humectant is an ethoxylated alcohol, the difference between the advance contact angle value and the retracted contact angle value of the multicomponent fiber is 0 to 30 degrees, and the multicomponent fiber is 0 to 15%. Disposable absorbent product which indicates the heat shrink value of. A plurality of multicomponent fibers comprising a liquid permeable surface sheet, a fluid absorbent layer, an absorbent structure and a liquid impermeable backsheet, wherein at least one of the liquid permeable surface sheet, the fluid absorbent layer or the liquid impermeable backsheet is made from a plurality of components. Biodegradable nonwovens, wherein one of the components a. Poly (lactic acid) polymer in an amount greater than 0 and less than 100% by weight, b. A polymer selected from the group consisting of polybutylene succinate polymers, polybutylene succinate adipate polymers, and mixtures of these polymers in an amount greater than 0 and less than 100% by weight, and c. An unreacted thermoplastic mixture comprising a humectant exhibiting a hydrophilic-hodgephilic balance ratio of 10-40 in an amount greater than 0 to 15% by weight, All of these weight percents are poly (lactic acid) polymers present in the thermoplastic composition; A polymer selected from the group consisting of polybutylene succinate polymers, polybutylene succinate adipate polymers, and mixtures of these polymers; And based on the total weight of the humectant, And wherein the plurality of multicomponent fibers are arranged in such a manner that the unreacted thermoplastic component is positioned on the surface of the multicomponent fiber. 16. The poly (lactic acid) polymer of claim 15, wherein the poly (lactic acid) polymer is present in an amount from 5% to 95% by weight and is selected from the group consisting of polybutylene succinate polymer, polybutylene succinate adipate polymer, and mixtures of these polymers. Wherein the selected polymer is present in an amount of 5% to 95% by weight and the humectant is present in an amount of 0.5% to 15% by weight. 16. The disposable absorbent article of claim 15 wherein the humectant exhibits a hydrophilic-hodgeotic balance ratio of 10-20. The disposable absorbent article of claim 15 wherein the humectant is an ethoxylated alcohol. 16. The disposable absorbent article of claim 15 wherein the multicomponent fiber exhibits a forward contact angle value of 0 to 75 degrees and a retracted contact angle value of 0 to 55 degrees. 20. The disposable absorbent article of claim 19 wherein the difference between the forward and backward contact angle values is between 0 and 30 degrees. 16. The disposable absorbent article of claim 15 wherein the multicomponent fiber exhibits a heat shrinkage value of 0-15%. 16. The poly (lactic acid) polymer of claim 15, wherein the poly (lactic acid) polymer is present in an amount of 75% to 90% by weight and is selected from the group consisting of polybutylene succinate polymer, polybutylene succinate adipate polymer, and mixtures of these polymers. The selected polymer is present in an amount of 5% to 20% by weight, the humectant is an ethoxylated alcohol, the difference between the advance contact angle value and the retracted contact angle value of the multicomponent fiber is 0 to 30 degrees, and the multicomponent fiber is 0 to 15%. Disposable absorbent product which indicates the heat shrink value of.  16. The disposable absorbent article of Claim 15 comprising a plurality of multicomponent fibers exhibiting a forward contact angle value of 0 to 80 degrees and a receding contact angle value of 0 to 60 degrees. delete The disposable absorbent article of claim 1 wherein the liquid permeable surfacesheet and the liquid impermeable backsheet comprise biodegradable nonwovens. delete The disposable absorbent article of claim 1, wherein the liquid permeable surface sheet, fluid absorbent layer, and liquid impermeable backsheet comprise biodegradable nonwovens. delete delete 8. The disposable absorbent article of Claim 7 wherein the liquid permeable surfacesheet and the liquid impermeable backsheet comprise biodegradable nonwovens. delete 8. The disposable absorbent article of Claim 7 wherein the liquid permeable surfacesheet, the fluid absorbent layer, and the liquid impermeable backsheet comprise biodegradable nonwovens. delete 16. The disposable absorbent article of Claim 15 wherein the liquid permeable surfacesheet and the liquid impermeable backsheet comprise biodegradable nonwovens. delete delete 16. The disposable absorbent article of Claim 15 wherein the liquid permeable surfacesheet, the fluid absorbent layer, and the liquid impermeable backsheet comprise biodegradable nonwovens.