MXPA06010679A - Wound d/ressings comprising hydrated hydrogels and enzymes - Google Patents

Abstract

An absorbent article comprising a laminated outer cover is disclosed. The laminated outer cover comprises an aliphatic-aromatic copolyester film including a filler material. The aliphatic-aromatic copolyester films have suitable breathability, vapor transfer and tensile strength properties while being substantially biodegradable.

Description

ABSORBENT ARTICLE THAT HAS A FILM OF ALIPHATIC-AROMATIC COPOLYESTER BACKGROUND OF THE INVENTION The present invention is directed to absorbent articles such as diapers containing an outer cover comprising a substantially biodegradable film material. More particularly, the present invention is directed to absorbent articles containing an outer cover made of a film material comprising an aliphatic-aromatic copolyester material showing improved biodegradable capacity after use. When filled with a filler material such as calcium carbonate, the aliphatic-aromatic copolyester film material has properties of high breathability, good barrier and tensile strength.

People rely on disposable absorbent articles, such as diapers, to make their lives easier. Commercially available diapers today are generally comfortable for the user, and provide a good barrier against diaper filtration. Despite providing good barrier properties against liquids, many commercially available diapers allow water vapor to pass through the diaper and into the environment to decrease the amount of moisture held against the skin and reduce the opportunity irritation and skin rash due to over hydration of the skin. In order to allow steam to pass through the diaper and into the environment while holding the liquid, many diapers comprise of a laminated outer covering, often referred to as an outer covering capable of breathing.

Generally, this outer cover capable of breathing is comprised of a nonwoven facing layer bonded to a layer of linear low density polyethylene facing the interior. The polyethylene layer will typically comprise calcium carbonate, which causes a series of openings to develop in the polyethylene layer when the film is stretched before use in the product, which finally allows the water vapor to pass through without allowing the liquid to pass through.

Although most commercially available diapers today comprise a suitable outer covering to achieve the objectives outlined above, a defect to date has been that the polyethylene used in the manufacture of the diaper, and specifically a layer of the outer cover, does not It is substantially biodegradable. Due to the popularity of diapers and other absorbent products and the large number of these products that are used each year, it can be beneficial to provide components of the absorbent article that exhibit improved biodegradable capacity in the waste fields after use and discarded .

SYNTHESIS OF THE INVENTION The present invention is directed to absorbent articles or products films comprising a film with improved biodegradable properties. The film, which is particularly useful as a component of an outer covering of an absorbent article, is comprised of an aliphatic-aromatic copolyester. The film also comprises calcium carbonate or other suitable fillers such that, with stretching, pores may develop around the filler material. These pores allow the passage of water vapor but not the passage of liquid. The film also possesses good properties of * high permeability and barrier and tensile strength.

In one embodiment, the film comprises filler and copolyester particles comprising three monomers: 1,4-butanediol, terephthalic acid, and adipic acid. The copolyester has an average molecular weight weight from about 90,000 to about 160,000 daltons and an average number of molecular weight from about 35,000 to about 70,000 daltons, and comprises a total of 40 mol% to about 60% by weight. mol of acid comonomers.

Therefore, the present invention is directed to an absorbent article comprising a laminated outer cover. The laminated outer cover comprises an aliphatic-aromatic copolyester film. The film comprises filler particles and a copolyester comprising from about 10 mol% to about 30 mol% aromatic dicarboxylic acid or ester thereof, from about 20 mol% to about 40 mol% acid aliphatic or ester dicarboxylic acid, and from about 30% mol to about 60% mol dhydric alcohol. The average molecular weight of the copolyester is from about 90,000 to about 160,000 daltons, and the average number of the copolyester molecular weight is from about 35,000 to about 70,000 daltons. The transition temperature of the copolyester glass is less than about 0 degrees centigrade.

The present invention is further directed to an absorbent article comprising a laminated outer cover. The laminated outer cover comprises a biodegradable stretched film of aliphatic-aromatic copolyester. The film comprises filler particles and a copolyester comprising from about 10 mol% to about 30 mol% terephthalic acid, from about 20 mol% to about 40 mol% adipic acid, and from about 30 mol% to about 60 mol% 1,4-butanediol. The copolyester has an average weight of the molecular weight from about 90,000 to about 160,000 daltons, and the average number of the molecular weight of the copolyester is from about 35,000 to about 70,000 daltons. The transition temperature of the copolyester glass is less than about 0 degrees centigrade.

BRIEF DESCRIPTION OF THE DRAWINGS Figure 1 is a plot of the geometrical mean of the tension in the direction of the magneus and in the direction transverse to the machine in data breaking against the level of calcium carbonate filler of several films.

Figure 2 is a graph of the geometrical mean of the data module in the machine direction and in the cross machine direction against the level of calcium carbonate filler of varis films.

DETAILED DESCRIPTION OF CURRENTLY PREFERRED INCORPORATIONS The present invention is generally directed to disposable absorbent products comprising an aliphatic-aromatic copolyester. The aliphatic-aromatic copolyester film, which in one embodiment can be used in combination with a spunbonded nonwoven material to form a composite outer shell, also comprises a filler material imparting several desirable characteristics including high vapor permeability properties, good barrier and tensile strength. Additionally, the aliphatic-aromatic copolyester films as described have improved biodegradable properties compared to conventional film materials, such as linear low density polyethylene.

Although it is described here primarily in connection with an outer cover of an absorbent product composite, such as a diaper, it will be recognized for one skilled in the art based on the description herein that the aliphatic-aromatic copolyester films described herein may be used in other areas of an absorbent article in addition to the outer cover. For example, fecal containment members, such as those described in U.S. Patent No. 5,676,661 (issued to Faulks et al.), May comprise the copolyester films described herein.

Additionally, even when described primarily herein in connection with a diaper, it will be recognized by one skilled in the art based on the description herein that the aliphatic-aromatic copolyester films described herein may also be used in a variety of other absorbent articles including , but not limited to, underpants for learning, and garments for adult incontinence. Also, the aliphatic-aromatic copolyester films described herein can also be used in connection with non-absorbent articles. Suitable non-absorbent articles include, for example, surgical covers, surgical gowns, and the like.

As used herein, the term "precursor film" means including films that have not been stretched before use and / or evaluation and analysis. This includes films that contain a filler material, such as calcium carbonate, that has not been stretched to create the pores around the calcium carbonate to allow water vapor to pass through the film.

As used herein, the term "stretched film" means including films that have been stretched to create pores around a filler material. These stretched films are ready for use in an absorbent article as they will allow water vapor to pass through.

As used herein, the term "biodegradable" or "biodegradable polymer" refers to a polymer that can be readily decomposed by biological means, such as bacterial action, heat and / or environmental humidity. When tested in accordance with test D6340-98, from the American Society for Testing and Materials (ASTM), a biodegradable polymer is one that is at least about 80% dissolved and / or decomposed (oxidized) after 1.80 days in a controlled fertilizer environment as indicated in the procedure.

Typically, the outer covering of a diaper is a multilayer laminate or a composite structure, such as a tapered multilayer laminated structure. Such a laminated composite structure provides the desired levels of extensibility as well as liquid impermeability and vapor permeability. The laminated structure typically comprises an outward facing and an inward facing layer, or a body facing layer. The outward facing layer is generally constructed of a non-woven material permeable to vapor and to the liguid, and the inward facing layer is generally constructed of a vapor permeable and liquid impervious material. Such combination allows the transmission of steam through the diaper and into the environment along with the support of the liquid in the diaper. The two layers are generally secured together thermally or by a suitable lamination adhesive. The thermal bond includes continuous or discontinuous bonding using a heated roll. The point union is an example of such a technique. On the thermal junctions it should also be understood to include various methods of ultrasonic, microwave, and other joining where heat is generated in the nonwoven or the film.

The outward facing layer permeable to the liquid can be any suitable material and is desirably one that provides a texture generally of the fabric type. Suitable materials capable of being tapered for the outward facing layer include non-woven fabrics, woven materials, and woven materials such as those described in U.S. Patent No. 4,965,122 (issued to Morman). Nonwoven fabrics or fabrics have been formed by many processes, for example, spinning processes, carded and bonded weaving processes, meltblowing processes, and spinning linked processes with spinning. Morman describes the stretching of a material, such as a non-woven in one direction in such a way that the material reversibly narrows or "narrows" in the perpendicular direction. The non-elastic material capable of being narrowed is desirably formed of at least one member selected from fibers and filaments of inelastic polymers. Such polymers include polyester, for example, polylactic acid, polyhydroxy alkanoate, polyethylene terephthalate, polyolefins, for example, polyethylene and polypropylene, and polyamides, for example, nylon 6 and nylon 66. A preferable material is a polypropylene linked with spinning. These fibers or filaments are used alone or in a mixture of two or more thereof. Suitable fibers for forming the material capable of being tapered include natural and synthetic fibers as well as formed and bicomponent polymer fibers, or multi-component fibers.

Many polyolefins are available for the production of fiber including, for example, fiber-forming polypropylenes including Escorene PD 3445 polypropylene from the Exxon Chemical Company and PF-304 from Himont Chemical Company. Polyethylenes such as ASPUN 6811A a linear low density polyethylene from Dow Chemical is also a suitable polymer. The non-woven fabric layer can be joined to impart a discrete bonding pattern with a prescribed bonding surface area. If a large area of union is present on the material capable of narrowing, it will break before narrowing. If there is not enough bonding area, then the material capable of narrowing will separate. Typically, the percentage joining area is in the range of about 5 percent to about 40 percent of the area of material capable of being narrowed.

A particular example of a suitable material from which the outward facing layer can be constructed is a nonwoven fabric of polypropylene bonded with yarn of 0.4 ounces per square yard or 14 grams per square meter which is capable of narrowing in the range from around 35% to around 45%. Typically, a suitable nonwoven material has a basis weight of less than about 30 grams per square meter. Also, while it is not necessary for the layer facing away from the outer cover to be permeable to the liquid, it is desired that it have a fabric-like texture.

Another example of a suitable material from which the outward facing layer can be constructed is a spun-bonded polylactic acid, such as that manufactured by Unitika (of Osaka, Japan) or Kanebo (of Tokyo, Japan).

The vapor-permeable, liquid-permeable facing layer is desirably constructed of a stretched aliphatic-aromatic copolyester film as described herein. The aliphatic-aromatic copolyester films of the present invention comprise: (1) a copolyester comprising an aromatic dicarboxylic acid or ester thereof, an aliphatic dicarboxylic acid or ester thereof, and a hydrophobic alcohol; and (2) filler particles. Optionally, a branched polyfunctional agent can also be incorporated into the aliphatic-aromatic copolyester films of the present invention.

Methods for preparing polyester in general and the aliphatic-aromatic copolyester in particular are known in the art. Most commonly, a mixture of monomers, including an aromatic dicarboxylic acid (designated HOOC-Ar-COOH in the lower equation), an aliphatic dicarboxylic acid (designated as HOOC-R-COOH in the equation below), and a diol (designated H0) -R '-OH, in the equation below) are reactive in the presence of a catalyst. Water is driven out, and under suitable conditions, a copolyester results (it can be either block or random copolymers), as shown in the following equation: nHOOC-Ar-COOH + mHOOC-R-COOH + (n + m) HO-R '-OH? - (OCArCO) n- (OR'0) n- (OCRCO) m- (OR'0) m- + (m + n) H20 Alternative synthetic methods include using methyl esters instead of carboxylic acids. In these methods methanol is volatilized instead of water during the reaction. Other methods of synthesis are also known.

For purposes of this invention, when it is noted that a polyester comprises several monomers, it is assumed that the starting materials were carboxylic acids and alcohols, as provided in the generalized equation above. While it is understood that other synthetic schemes may employ other types of monomers, reference to copolyester comprising the designated carboxylic acids and alcohols are intended to define the finished polymer, not the actual starting materials. Also, the precise polymer synthesis method is not critical insofar as the desired polymer properties are achieved.

Any aromatic dicarboxylic acid known in the art can be used as the aromatic dicarboxylic acid monomer of the copolyester of the films described herein. Useful aromatic dicarboxylic acids include unsubstituted or substituted aromatic dicarboxylic acids and lower alkyl (C? -C6) aromatic dicarboxylic acid esters. Examples of useful di-acid moieties include those derived from terephthalates, isophthalates, naphthalates, and bibenzoates. Specific examples of useful aromatic dicarboxylic acid components include terephthalic acid, dimethyl terephthalate, isophthalic acid, dimethyl isophthalate, 2,6-naphthalene dicarboxylic acid, dimethyl-2,6-naphthalate, 2,7-naphthalenedicarboxylic acid, dimethyl-2, 7-naphthalate, 3,4'-diphenyl ether dicarboxylic acid, dimethyl-3,4'-diphenyl ether dicarboxylate, 4,4'-diphenyl ether dicarboxylic acid, dimethyl-4,4'-diphenyl ether dicarboxylate, 3,4 '- diphenyl sulfide dicarboxylic acid, dimethyl-3,4'-diphenyl sulfonate dicarboxylate, 4,4 '-diphenyl sulfide dicarboxylic acid, dimethyl-4,4'-diphenyl sulfonate dicarboxylate, 3,4' -diphenyl sulfonate dicarboxylic acid, dimethyl-3 , 4'-diphenyl sulfone dicarboxylate, 4,4'-diphenyl sulfone dicarboxylic acid, dimethyl-4,4'-diphenyl sulfone dicarboxylate, 3,4'-benzophenonedicarboxylic acid, dimethyl-3,4'-benzophenonedicarboxylate, 4,4 ' -benzofenonedicarboxylic acid, dimethyl -4,4'-benzophenonedicarboxylated, 1,4-dicarboxylic acid naphthalene, dimethyl-1,4-naphthalate, 4,4'-methylene bis (benzoic acid), dimethyl-4,4'-methylenebis (benzoate), and the like and mixtures of two or more thereof. Preferably, the aromatic dicarboxylic acid component is derived from terephthalic acid, dimethyl terephthalate, isophthalic acid, dimethyl isophthalate, 2,6-naphthalene dicarboxylic acid, dimethyl-2,6-naphthalate, or mixtures of two or more thereof. The carboxylic acid chlorides or anhydrides of these monomers may also be suitable.

The aromatic dicarboxylic acid is present in the aliphatic-aromatic copolyester in an amount from about 10 mol% to about 30 mol%, optionally from about 15 mol% to about 25 mol%, and optionally from about from 17.5 mol% to about 22.5 mol%.

Any aliphatic dicarboxylic acid known in the art can be used as the component of the aliphatic dicarboxylic acid monomer of the copolyester of the films described herein. Useful aliphatic dicarboxylic acid components include cyclic, or branched, linear, substituted aliphatic dicarboxylic acids, and the lower alkyl esters thereof, preferably having 2-36 carbon atoms. Examples of useful components of the aliphatic dicarboxylic acid include oxalic acid, dimethyl oxalate, malonic acid, dimethyl malonate, succinic acid, dimethyl succinate, methylsuccinic acid, glutaric acid, dimethyl glutarate, 2-methyl glutaric acid, 3-methyl glutaric acid, adipic acid, dimethyl adipate, 3-methyladipic acid, 2, 2, 5, 5-tetramethylhexanedioic acid, pimelic acid, suberic acid, azelaic acid, dimethyl azelate, sebacic acid, 1,11-undecanedicarboxylic acid, 1,10-decanedicarboxylic acid, undecanedioic acid , 1,12-dodecanedicarboxylic acid, hexadecanedioic acid, docosanedioic acid, tetracosanedioic acid, dimer acid, 1,4-cyclohexanedicarboxylic acid, dimethyl-1,4-cyclohexanedicarboxylate, 1,3-cyclohexanedicarboxylic acid, dimethyl-1,3-cyclohexanedicarboxylate, 1,1-cyclohexanediacetic acid, and the like and mixtures of two or more thereof. Carboxylic acid chlorides or anhydrides may also be suitable. Preferred aliphatic acids or esters include succinic acid, dimethyl succinate, glutaric acid, dimethyl glutarate, adipic acid, dimethyl adipate, and dimer acid.

The aliphatic dicarboxylic acid is present in the aliphatic-aromatic copolyester in an amount from about 20 mol% to about 40 mol%, optionally from about 25 mol% to about 35 mol%, and optionally from about from 27.5% mol to around 32.5% mol.

Any dihydric alcohol, glycol, or diol known in the art can be used as the dihydric alcohol component of the aliphatic-aromatic copolyester of the film of the present invention. Examples include substituted or unsubstituted; straight, branched, cyclic aliphatic, aromatic aliphatic, or aromatic diols having, for example, from 2 carbon atoms to 36 carbon atoms and poly (alkylene ether) diols with molecular weights preferably from about 250 to about 4,000 . Specific examples of the useful diol component include ethylene glycol, 1,3-propanediol, 1,4-butanediol, 1,6-hexanediol, 1,8-octanediol, 1,10-decanediol, 1, 12-dodecanediol, 1,14 - tetradecanediol, 1,16-hexanedecanediol, 4,48-bis (hydroxymethyl) -tricyclo [5. .1.0 / 2.6] decane, 1,4-cyclohexanedimethanol, di (ethylene glycol), tri (ethylene glycol), poly (ethylene oxide) glycols, poly (butylene ether) glycols, isosorbide, and the like and mixtures of two or more. Preferred dihydric alcohols include ethylene glycol, 1,3-propanediol, 1,4-butanediol, 1,6-hexanediol, and poly (ethylene oxide) glycols.

The dihydric alcohol is present in the aliphatic-aromatic copolyester in an amount of from about 30 mol% to about 60 mol%, optionally from about 45 mol% to about 55 mol%, and optionally from about 47.5 mol% to about 52.5 mol%.

The aliphatic-aromatic copolyester component of the films described herein can be formed by including an optional polyfunctional branched agent, such as any material with three or more carboxylic acid functions, hydroxy functions, or a mixture thereof. Specific example of useful polyfunctional branched agent component includes 1, 2,4-benzenetricarboxylic acid (trimellitic acid), trimethyl-1,2,4-benzenetricarboxylate, 1,2,4-benzenetricarboxylic anhydride (trimethyl anhydride), 1,3,5-benzenetricarboxylic acid, 1,2,4,5-benzenetetracarboxylic acid (pyromellitic acid), 1, 2,4,4-benzenetetracarboxylic dianhydride (pyromellitic anhydride), 3,3 ', 4,4'-benzophenotetracarboxylic acid di-anhydride, 1,4,5,8-naphthalenetetra-anthrahydric di-anhydride, citric acid, tetrahydrofuran-2, 3- , 4, 5-tetracarboxylic acid, 1,3,5-cyclohexanetricarboxylic acid, pentaerythritol, 2- (hydroxymethyl) -1, 3-propanediol, 2,2-bis (hydroxymethyl) propionic acid, and the like and mixtures of two or more thereof. The branched polyfunctional agent may be included when a higher resin melt viscosity is desired for specific end uses. Excessive fractions of the polyfunctional groups (eg, more than two functional groups) can lead to the formation of a gel fraction or insoluble cross-linked material. The total amount of polyfunctional branched agent may be less than about 10% of the total composition of the monomer. Alternatively, the polyfunctional branched agent may be less than about 3%, or less than about 1%.

In an embodiment of the present invention, the total amount of the comonomer acid present in the component • of the aliphatic-aromatic copolyester of the films described herein is from about 40 mol% to about 60 mol%, that is, the amount molar of the aromatic dicarboxylic acid in addition to the molar amount of the aliphatic dicarboxylic acid present in the aliphatic-aromatic copolyester is from about 40 mol% to about 60 mol%. Desirably, the total amount of the comonomer acid present in the aliphatic-aromatic copolyester is from about 45 mol% to about 55 mol%, and even more desirably from about 47.5 mol% to about 52.5 mol%.

The total amount of the comonomer acid present in the aliphatic-aromatic copolyester component of the films described herein affects the adhesion properties between the aliphatic-aromatic copolyester and the filler component of the film, which is described below. In order for the films to be suitable for use in absorbent products, generally low adhesion between the filler material and the copolyester is desired. If much comonomer acid is present in the c-polyester, the adhesion to the filler material is very high. And the filler material can not act properly to effect the creation of pores around the filler material when the film is stretched. This results in the film having insufficient vapor permeability.

The aliphatic-aromatic copolyester component of the films described herein has an average molecular weight and an average molecular weight number such that the copolyester has an adequate tensile strength.

If the molecular weight numbers are very small, the copolyester will be sticky and will have very low tensile strength. If the molecular weight numbers are very high, several processing problems will be faced, such as a need for increased temperature to cope with increased viscosity. Suitable average molecular weight weights for copolyesters are from about 90,000 to about 160,000 daltons, desirably from about 100,000 to about 130,000 daltons, and more desirably from about 105,000 to about 120,000 daltons. Suitable number of average molecular weights for copolyesters are from about 35,000 to about 70,000 daltons, more desirably from about 40,000 to about 60,000 daltons, and more desirably from about 42,000 to about 50,000 daltons.

The aliphatic-aromatic copolyester films of the present invention generally have a thickness suitable for use in an absorbent article, such as a diaper. Typically, the films will have a thickness of less than about 250 microns, and desirably from about 2.5 microns to about 130 microns. A useful standard film in a diaper can have a thickness from about 10 microns to about 25 microns, for example. In some embodiments, it may be desirable to use a film having a thickness of about 50 microns.

The copolyesters described herein for use in the films of the present invention have a glass transition temperature such that the copolyester has desirable flexibility characteristics for use in a film. As used herein, "glass transition temperature" means that temperature at which a polymer becomes hard and brittle, such as glass. For the copolyesters described herein, it is desirable that they have a glass transition temperature of less than about 0 degrees centigrade, and optionally less than about -10 degrees centigrade. With glass transition temperatures of less than these values, the copolyesters have suitable properties for use in the absorbent articles described herein.

The aliphatic-aromatic copolyester films of the present invention have an adequate water vapor transmission rate such that the film allows a substantial amount of water vapor to pass through, such that the probability of over-hydration of the skin is reduced. . The films of the present invention can be made substantially vapor permeable through the addition of a particle or filler material during the manufacture of the films. During fabrication, the filler material is added and mixed with the polymers before casting the polymers in a film. Once emptied, the films are stretched to create tiny pores to form in the film around the filler particles. These pores allow the transmission of steam, but do not allow a substantial amount of liquid to pass through.

The filler particles can include any suitable inorganic or organic filler. The filler particles are preferably small, in order to maximize the transmission of steam through the voids. Generally, the filler particles should have a mean particle diameter of about 0.1-10.0 microns, optionally about 0.5-5.0 microns, and optionally about 1.5-3.0 microns. Examples of organic fillers include starches, such as thermoplastic starches or pre-gelled starches, micro-crystalline cellulose, and polymeric drops. Other suitable fillers include, without limitation, calcium carbonate, clays not capable of swelling, silicon, alumina, barium sulfate, sodium carbonate, talc, magnesium sulfate, titanium dioxide, zeolites, aluminum sulfate, diatomaceous earth, sulfate of magnesium, magnesium carbonate, barium carbonate, kaolin, mica, carbon, calcium oxide, magnesium oxide, aluminum hydroxide, and polymer particles. Calcium carbonate is a presently preferable filler material.

The filler particles can optionally be coated with a smaller amount (eg, up to 2% by weight) of a fatty acid or other material to facilitate their dispersion in the polymer matrix prior to emptying.

Suitable fatty acids include without limitation stearic acid, or a longer chain fatty acid such as a behenic acid. The amount of filler particles in the film should be in the range from about 30% to about 80% (by weight of film and filler particles), optionally from about 40% to about 70% (by weight of film and filler particles), optionally from about 50% to about 65% (by weight of film and filler particles), and optionally from about 50% to about 55% (by weight of film and of filler particles).

The filler particles can be micro-porous or not. Micro-porous refers to a material that has pores, generally in the range from about 2 angstroms to about 50 angstroms, which form a continuously interconnected hollow space or network. The shape of the filler particle can be generally spherical or round. Other additions include plate type, needle type, or irregular shapes, tips, or sharp edges.

In some embodiments of the present invention, the stretched films described herein have a water vapor transmission rate of at least about 2000 grams per square meter per day, optionally of at least about 5000 grams per square meter per day, optionally of at least about 10,000 grams per square meter per day, and optionally 25,000 grams per square meter per day. At these levels, the films allow a sufficient amount of water vapor to pass through to protect the skin from over-hydration.

In addition to an adequate water vapor transmission rate, it is also desirable that the stretched films described herein resist a hydrostatic pressure such that the films do not allow a substantial amount of liquid water to pass through with the application of pressure. Usually, it is desirable that the films withstand a hydrostatic pressure of at least about 60 millibars, optionally of at least about 80 millibars, optionally of at least about 120 millibars, and optionally of at least about 180 millibars without allowing to liquid water to pass.

In addition to an adequate water vapor transmission rate and an adequate resistance to hydrostatic pressure, it is also desirable that the films described herein have an adequate modulus of elasticity. The tensile properties of the films described herein can be determined by one skilled in the art using the Standard Test Method for the Traction Properties of Plastics, D 938-99 of the American Society for Testing and Materials, published by the American Society for Testing and Materials, West Conshohocken, Pennsylvania. The procedure indicates that the breaking stress is the tensile stress at the breaking elongation (for example, the elongation at which the sample breaks); the production tension is the tensile stress at the first point on the voltage-tension curve at which an increase in tension occurs without an increase in tension; and the modulus of elasticity is the ratio of voltage (nominal) to corresponding voltage below the proportional limit of a material.

The precursor films desirably have a modulus of elasticity that is suitable for characterizing a desirable adhesion between the filler particles and the film. As used herein, the term "modulus ratio" means the modulus of elasticity of a filled precursor film divided by the modulus of elasticity of an unfilled film. The precursor films comprise about 50% filler material, a modulus ratio is desirably from about 0.5 to about 3.5, optionally from about 0.75 to about 3.25; and optionally from around 1.0 to around 3.0. The precursor films comprise about 55% filler material, the modulus ratio is from about 0.45 to about 4.25, optionally from about 0.75 to about 3.75, and optionally from about 1.0 to about 3.5. Within these proportions, a film has the desired modulus of elasticity to provide a desired adhesion rate between the film and the filler particles.

Additionally, the precursor films desirably have adequate elongation characteristics; that is, the precursor film can be lengthened by a sufficient amount to achieve the desired thickness of the film and the level of ability to breathe before the break. The measurements of the elongation of a film include% tension at the breaking point, breaking stress (mPa) and production tension (MPa). The precursor films comprise about 50% filler material, it is desirable that the film be stretched in the machine direction and have from about 50% strain to about 1000% strain, optionally from about 300% tension at about 1000% tension, and optionally from about 450% tension to about 1000% tension before breaking. As used herein, "tension" means the ratio of the length of the film stretched to the length of the precursor film minus one, which is typically reported as a percentage.

For precursor films comprising about 55% filler material, it is undesirable for the film to be stretched in the machine direction and have from about 50% tension to about 1000% strain, optionally from about 75% voltage at about 1000% voltage, and optionally from about 250% voltage to about 1000% voltage before breaking.

It is also beneficial for precursor films to have an adequate proportion of output in the direction of the machine. As used herein, "take-out ratio" means the length of a stretched film divided by the length of an unstretched film. In one embodiment, the output ratio of the precursor films described herein is at least about 2.5 to about 10, optionally from about 3.5 to about 10, and optionally from about 4.5 to about 10.

For precursor films comprising about 50% filler material, it is desirable that the film be stretched in the transverse direction and not break up to about 50% tension at about 1000% strain, optionally from about 300 % voltage at about 1000% voltage, and optionally from about 450% voltage to about 1000% voltage before breaking. For precursor films comprising about 55% filler material, it is desirable that the film be stretched in the transverse direction and not break up to about 50% tension at about 1000% strain, optionally from about 250% voltage at about 1000% voltage, and optionally from about 350% voltage to about 1000% voltage before breaking.

For precursor films comprising about 50-55% filler material, it is desirable that the 'film can be stretched in the direction to the machine and have a breaking voltage from about 4 to about MPa, optionally from around 6 to around 20 MPa, and optionally from about 8 to about 15 MPa. For precursor films comprising from about 50 to about 55% filler material, it is also desirable that the film be stretched in the machine direction and have a production tension from about 4 to about 16 MPa , optionally from about 6 to about 14 MPa, and optionally from about 8 to about 10 MPa. As one skilled in the art will understand based on the current description, the films described herein can be stretched by any known methods, in the art. For example, the films may be blown, using tempting hooks, or by the use of differential speeds on the rollers.

For stretched films, it is preferable that the film has a modulus of elasticity of less than about 300 MPa. In some embodiments, the modulus of elasticity can be from about 50 to about 250 MPa, optionally from about 70 to about 150 MPa, and optionally from about 80 to about 100 MPa. Regarding elongation, it is generally preferable that the stretched films are capable of being elongated in the machine direction by at least about 70% without breaking. In some embodiments, adequate elongation in the machine direction is from about 15 to about 100% tension, optionally from about 20 to about 60%, and optionally from about 30 to about 50% tension before of the break. Stretched films are also desirably capable of being stretched in the transverse direction from about 150 to about 500% tension, optionally from about 175 to about 400% tension, and optionally from about 200 to about 300% of tension before breaking. Also, when being stretched in the machine direction, the stretched films desirably have a breaking stress of from about 10 to about 50 MPa, optionally from about 15 to about 40 MPa, and optionally from about 25 to around 35 MPa.

As noted above, the aliphatic-aromatic copolyesters described herein can be prepared from the aliphatic dicarboxylic acid, aromatic dicarboxylic acid, and dihydric acid monomers using any conventional process known to those skilled in the art. For example, the copolyesters can be prepared using a conventional technique, or a conventional melt polymerization method. Additionally, the aliphatic-aromatic copolyester can be obtained commercially from BASF (of Mount Olive, New Jersey), IRe Chemical (of Seoul, Korea), and of Eastman Chemical (of Kingsport, Tennessee).

The films comprise the copolyester and filler particles described herein and suitable for use in the absorbent articles described herein can be prepared using any conventional film-forming technique including extrusion casting and meltblowing. An extrusion casting technique can be used in combination with film tempering, film stretching, and / or heat setting after drawing operations.

In one embodiment, during the operation of the film casting, the casting rolls are optionally fixed at a temperature on the surface of the roll from about 20 degrees centigrade to about 70 degrees centigrade, optionally from about 30 degrees centigrade to about of 60 degrees Celsius, and optionally from around 45 degrees Celsius to around 55 degrees Celsius. After the film is emptied onto a casting roller, the film can be cooled and tempered at temperatures in the range from about 40 degrees centigrade to about 60 degrees centigrade. This cooling and tempering occurs as the film is transported (on a series of rollers, on a conveyor belt, or on an air conveyor, etc.) under low tension. In this context, the "low voltage" indicates that the film is stretched less than 100%, optionally less than 25%, or less than 10% as transported. This section of the film making apparatus extends from the emptying roller to the drawing operation and is referred to as the emptying line.

The length of the emptying line is from around 5 meters to around 50 meters, optionally from around 10 meters to around 30 meters. A longer line length can provide longer residence time to fix the film and temper it before the film enters the stretch operation. Longer residence time will improve the tensile properties of the film such as strength, pull-out ability, and other properties useful for stretching operations.

In the stretching operation, the film is preferably drawn at temperatures of from about 15 ° C to about 50 ° C, optionally from about 25 ° C to about 40 ° C, and optionally from about 30 ° C. C at around 40 ° C. Cold stretching may improve the hollow formation around the filler particles, but may limit the film stretch. Optionally, the film is stretched in two zones with optional heating at a range of from about 30 ° C to about 50 ° C between the stretching zones. Either a single stretch or a zone or multiple zones can be employed. The films can be stretched uniaxially, and axially or both uniaxially and biaxially (at different times). The uniaxial stretch can be in the machine direction, in the transverse direction or on a deviation.

The pulling or pulling ratio during the stretching operation is from about 2.5 to about 10; for example, the linear speed of the film exiting the stretching operation is 2.5 to 10 times the speed of the precursor film entering the stretching operation. Optionally, the stretch or pull ratio is from around 3.5 to around 7.

After stretching, the film is optionally seated with heat to stabilize the stretched film. Settling with heat can be achieved at temperatures from about 40 ° C to about 80 ° C, and optionally from about 50 ° C to about 70 ° C. The settling operation with heat can reduce the shrinkage of the stretched film and improve film properties and ability to breathe. Any device in the art of seating with heat can be used including heated rollers and furnace settling. Additional treatments can be applied to improve the properties of stretch film such as surface treatments, ultraviolet treatments, ultrasonic treatments and plasma treatments.

EXAMPLE 1 In this example, the aliphatic-aromatic copolyester films were prepared using two aliphatic-aromatic copolyester resins as starting materials. A group of films was prepared without any filler material and a second group of films was prepared using calcium carbonate filler materials at various levels (% by weight of filler based on the total weight of the film and filler). A group of filled and unfilled films was prepared using the aliphatic-aromatic copolyester Ecoflex F BX 7011 (from BASF), and a group of films was prepared using EnPol G8060M (IRe Chemical) aliphatic-aromatic copolyester.

Prior to extrusion of the films from the aliphatic-aromatic copolyesters, a group of Ecoflex copolyesters and a group of EnPol copolyesters were mixed separately with Omya (from Proctor, Vermont) a calcium filler material of 2sst of 2 microns using a twin screw combination extruder ZSK-30 from Werner & Pfleiderer (from Ramsey, New Jersey). The mixtures of the calcium carbonate filler material and each resin (in melted form) were made at filler levels equal to 40% by weight (based on the total weight of the film and the filler), 50% by weight, 55% by weight, 60% by weight and 65% by weight.

After all the resins were mixed with the filler, the films of each mixture were extruded. The films were extruded using the Rheocord 90 upper bench twin screw extruder HAAKE (from Thermo Electron Corporation, Woburn, Massachusetts) having an eight inch die. The extruder had three temperature zones, a melt pump with controlled temperature, and a matrix with a controlled temperature. Unfilled films comprising each copolyester were also extruded.

The temperature profile used for setting Ecoflex copolyester in a film was as follows: 160 ° C, 170 ° C, 170 ° C (extruder temperatures), 170 ° C (melt pump temperature), and 160 ° C (matrix temperature). The temperature profile used for the setting of the copolyester EnPol in a film was as follows: 170 ° C, 180 ° C, 180 ° C (extruder temperatures), 180 ° C (melt pump temperature) and 180 ° C (die temperature). The temperature profiles were selected to achieve the proper viscosity for handling the melt polymer. Both filled and unfilled films having a thickness ranging from about 15 micrometers to about 50 micrometers were extruded.

EXAMPLE 2 In this example, the tensile strength test was carried out on several aliphatic-aromatic copolyester precursor films prepared in example 1. Each film that was tested was cut into a film strip 3 millimeters wide by 50 millimeters long for the test. The testing was done according to ADTM D-638 using a dog bone configuration, a measurement length of 18 millimeters, and a crosshead speed of 127 millimeters per minute. The films were stretched under these conditions until they broke.

The following films based on Exoflex and InPol were stretched and tested in the machine direction and in the transverse direction: (1) 0% calcium carbonate at 25 micrometers; (2) 40% calcium carbonate at 50 microns; (3) 50% calcium carbonate at 50 microns; (4) 55% calcium carbonate at 50 microns; (5) 60% calcium carbonate at 50 microns. Also, linear low density polyethylene was tested for comparison purposes. The results are set out in Tables 1-5.

Table 1: Stress Resistance Properties of Linear Low Density Polyethylene Films Table 2: Stress Properties in the Address of the Copolyester Precursor Film Machine Table 3: Stress Properties in the Cross Direction to the Machine of the Precursor Films Table 4: Stress Properties in the Direction of the Copolyester Precursor Film Machine Table 5: Tension Properties in the Cross Direction to the Precursor Film Machine Figures 1 and 2 are derived from the data of Tables 2-5. Figure 1 draws the geometrical mean of the stress data at the break in the machine direction and i in the transverse direction against the fill level of calcium carbonate. Figure 2 draws the geometrical mean of the module data in the machine direction and in the transverse direction j against the filling level of: calcium carbonate. The geometric mean is calculated by taking the square root of the product of the address data of the machine times the address data transverse to the machine.

The data in Tables 2-5 and in Figures 1 and 2 show that the tension to the break for the Exoflex and! InPol (for example 0% calcium carbonate) 'is very close, j Also unfilled films have similar modules. But as the fill level increases, the values for the Ecoflex and EnPol films diverge. Considering films that contain 40% or more filler, EnPol-based films are stiffer than Ecoflex-based films as shown by the upper module and the lower stress at the break for films based on EnPol in relation to Ecoflex-based films. These differences indicate that the filler particles adhere to the EnPol-based films more strongly than the filler films adhere to: the Ecoflex-based films. i It is desirable that the filler particles do not adhere very strongly to the copolyesters. The weaker adhesion allows more stretch of the film without breaking. Also, the weaker adhesion results in a separation (separation) of the polymer filler particles when | the movie is stretched. Such separation provides gaps in the film, which improve vapor permeability. These gaps also tend to result in a lower density film.

EXAMPLE 3 In this example, several Ecoflex-based and EnPol-based precursor films extruded in Example 1 were stretched to produce the stretched films to create pores around said calcium carbonate filler material so that the films can be further evaluated for Hydrohead pressure, water vapor transmission rate and tensile strength. The films were stretched to create the pores before further analysis in order to test films like these would be used in a commercial incorporation; that is, the filled films extruded in Example 1 would first be stretched according to the procedure in this example before being used in the absorbent article since this stretch creates the pores in the film that allow vapor transmission.

Each, film was cut into sheets measuring 'about 18.0 centimeters wide by about 10.0 centimeters long. Each film was then stretched to around 470% (tension) of its original length at a rate of 840 millimeters per minute, which resulted in a stretch of 2, 200% / minute in a pull of 350%. All Ecoflex films were successfully conditioned to a concentration of 60% calcium carbonate. The movies EnPol may not be successfully stretched to the same extent with more than a 40% concentration of calcium carbonate because the film broke at higher calcium carbonate loading levels. The theory is that excessive adhesion of the copolyester to the filler particles resulted in a lower tolerance of the EnPol film for stretching than the Ecoflex films.

To account for the difference in adhesion between the two films, the analytical work (gel permeation chromatography for determination of molecular weight) was carried out on the copolyesters Ecoflex and EnPol. It was determined that EnPol resins had a higher average weight molecular weight (119,300 daltons) compared to Ecoflex resins (109,850 daltons). The EnPol resin also had a lower number average molecular weight (43,800 daltons) compared to the Ecoflex resin (46,700 daltons). It was also determined that the EnPol resin had a higher total amount of acid monomer content (57 mol%) compared to Ecoflex (51 mol%). It appears that the combination of differences in molecular weight and difference in total acid monomer content caused by the EnPol films to have an increased amount of tackiness that does not allow as much debanking compared to Ecoflex films.

EXAMPLE 4 In this example, the resistance to hydrostatic pressure of several films stretched according to example 3 was evaluated. The resistance of a material to the penetration of liquid is measured by the hydrostatic pressure. The hydrostatic pressure resistance of the various films was determined using the ASTM standard test method for coated fabrics, designation D751, "Hydrostatic Resistance Procedure Type A-Mullen Tester" with the exception that in paragraph 40.1.1, The reading of the marker is taken when the third drop of water is observed, rather than when the first drop is observed. All the films were stretched in the direction of the machine.

Films comprising Ecoflex stretched according to Example 3 below were evaluated: Exoflex with 55% calcium carbonate (25 micrometers); Exoflex with 50% calcium carbonate (25 micrometers); and Ecoflex with 40% calcium carbonate (20 microns). The next film comprising EnPol, also stretched according to example 3 was evaluated: EnPol with 40% calcium carbonate (23 micrometers). The results of the hydrostatic pressure analysis are shown in Table 6.

Table 6: Hydrohead pressure As indicated by the data in Table 6, all films tested had high head pressure resistance values, which indicates that all films were resistant to allowing water droplets to pass through them during use. Notably, the Ecoflex comprising 40% calcium carbonate (20 micrometers) had a value of 148.00, which indicates that it would be highly resistant to the passage of the liquid through them.

EXAMPLE 5 In this example, the water vapor transmission rates of several stretched films according to example 3 were evaluated. The water vapor transmission rate measures the ability of water vapor to penetrate through a film. The water vapor transmission rate of several films was determined using the ASTM F-1249 standard using a Permatran 100 K analyzer available from MOCON (from Minneapolis, Minnesota). The films were either stretched in the direction of the machine or in the transverse direction as noted below.

The following films comprising Ecoflex were evaluated: Exoflex with 55% calcium carbonate (19 micrometers in the machine direction); Exoflex with 55% calcium carbonate (25 micrometers in the machine direction); Ecoflex with 55% calcium carbonate (25 micrometers in the transverse direction); Ecoflex with 50% calcium carbonate (23 micrometers in the machine direction); Ecoflex with 50% calcium carbonate (19 micrometers in the machine direction); Ecoflex with 40% calcium carbonate (17 micrometers in the machine direction); and Ecoflex with 40% calcium carbonate (22 micrometers in the machine direction). Films comprising the following EnPol were evaluated: EnPol with 40% calcium carbonate (18 micrometers in the machine direction); EnPol with 40% calcium carbonate (20 micrometers in the transverse direction); EnPol with 40% calcium carbonate (15 micrometers in the transverse direction); EnPol with 40% calcium carbonate (25 micrometers in the machine direction); and EnPol with 40% calcium carbonate (20 micrometers in the machine direction). The results of the analysis of the water vapor transmission rate are shown in Table 7.

All Ecoflex films were prepared from resins having a temperature when leaving the matrix during setting of around 175 ° C. The EnPol tested at 40% calcium carbonate was melted at around 160 ° C.

Table 7: Water Vapor Transmission Rate The data in Table 7 demonstrate that films with higher fill filler levels tend to have higher water vapor transmission rates than films with a lower filler load.

EXAMPLE 6 In this example, the tensile strengths of the various stretched films prepared according to the example 3 were evaluated for the module,% of breaking stress ,. peak effort, and peak load using the same test procedure as set forth in example 2. The films were drawn in the machine direction (Table 8) and in the cross machine direction (Table 9). The results are established in Tables 8 and 9.

Table 8: Stress Properties of Stretch Breathable Films; Stretched Movies e? Machine Direction and Tested in the Machine Direction Table 9: Stress Properties of Stretch Breathable Films; Films Stretched in the Direction of the Machine and Tested in the Cross Direction As the data in these Tables indicates, both films based on EnPol and Ecoflex had properties similar to the LLPDE once stretched.

It will be appreciated that the details of the above embodiments, given for purposes of illustration, should not be considered as limiting the scope of this invention. Although only a few example embodiments of this invention have been described in detail above, those skilled in the art will appreciate that many modifications to example embodiments are possible in materially departing from the teachings and novel advantages of this invention. Therefore, all such modifications are intended to be included within the scope of this invention which is defined in the following claims and all equivalents thereof. Furthermore, it is recognized that many incorporations can be conceived which do not achieve all the advantages of some incorporations, particularly of the preferred embodiments, but that the absence of a particular advantage should not be considered as necessarily signifying that such incorporation is beyond the scope of the present invention.

Claims (20)

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

1. An absorbent article comprising a laminated outer cover, the laminated outer cover comprises a biodegradable stretched aliphatic-aromatic copolyester film, the film comprises filler particles and a copolyester comprising from about 10 mol% to about 30 mol% of aromatic dicarboxylic acid or ester thereof, of from about 20 mol% to about 40 mol% of aliphatic dicarboxylic acid or ester thereof, from about 30 mol% to about 60 mol% of dihydric alcohol, and wherein The weight average molecular weight of the copolyester is from about 90,000 to about 160,000 daltons, and wherein the number average molecular weight of the copolyester is from about 35,000 to about 70,000 daltons, and wherein the transition temperature The copolyester glass is less than around 0 ° C.

2. The absorbent article as claimed in clause 1, characterized in that the filler particles are present in the film in an amount of from about 30% (by weight of the film and filler particles) to about 80% ( by weight of the film and filler particles).

3. The absorbent article as claimed in clause 1, characterized in that the filler particles are selected from the group consisting of calcium carbonate, non-swelling clays, silica, alumina, barium sulfate, sodium carbonate, talc, sulfate magnesium, titanium dioxide, zeolites, aluminum sulfate, diatomaceous earth, magnesium sulfate, magnesium carbonate, barium carbonate, kaolin, mica, carbon, calcium oxide, magnesium oxide, aluminum hydroxide, and polymer particles.

4. The absorbent article as claimed in clause 1, characterized in that the aromatic dicarboxylic acid or the ester thereof is selected from the group consisting of substituted and unsubstituted aromatic, dicarboxylic acids and C? -C6 esters of the aromatic dicarboxylic acids .

5. The absorbent article as claimed in clause 1, characterized in that the aliphatic dicarboxylic acid or ester thereof is selected from the group consisting of oxalic acid, dimethyl oxalate, malonic acid, dimethyl malonate, succinic acid, dimethyl succinate, methylsuccinic acid , glutaric acid, dimethyl glutarate, 2-methylglutaric acid, 3-methylglutaric acid, adipic acid, dimethyl adipate, 3-methyladipic acid, 2, 2, 5, 5-tetramethylhexanedioic acid, pimelic acid, suberic acid, azelaic acid, dimethyl azelate , sebacic acid, 1,11-undecanedicarboxylic acid, 1,10-decanedicarboxylic acid, undecanedioic acid, 1,12-dodecanedicarboxylic acid, hexadecanedioic acid, docosanedioic acid, tetracosanedioic acid, 5-dimer acid, 1,4-cyclohexanedicarboxylic acid, dimethyl- 1, 4-cyclohexanedicarboxylate, 1,3-cyclohexanedicarboxylic acid, dimethyl-1,3-cyclohexanedicarboxylate, 1,1-cyclohexaned acid iacético, and mixtures of two or more of them.

6. The absorbent article as claimed in clause 1, characterized in that the dihydric alcohol is selected from the group consisting of unsubstituted or substituted, straight-chain, branched or cyclic aliphatic, aliphatic-aromatic, or aromatic diols 5 having from 2 carbon atoms to 36 carbon atoms and poly (alkylene ether) glycols with molecular weights of from about 250 to about 4,000.

7. The absorbent article as claimed in clause 1, characterized in that the film additionally comprises a polyfunctional branching agent.

8. The absorbent article as claimed in clause 7, characterized in that the polyfunctional branching agent is selected from the group consisting of a material with three or more carboxylic acid functions, three or more hydroxyl functions and mixtures thereof .

9. The absorbent article as claimed in clause 1, characterized in that the aromatic dicarboxylic acid is terephthalic acid, the aliphatic dicarboxylic acid is adipic acid and the dihydric alcohol is 1,4 butanediol.

10. The absorbent article as claimed in clause 9, characterized in that the filler material is calcium carbonate.

11. The absorbent article as claimed in clause 1, characterized in that the film has a thickness of less than about 250 microns.

12. The absorbent article as claimed in clause 1, characterized in that the laminated outer cover further comprises a non-woven material.

13. The absorbent article as claimed in clause 12, characterized in that the non-woven material is a non-woven material bonded with spinning.

14. The absorbent article as claimed in clause 12, characterized in that the non-woven material has a basis weight of less than about 30 grams per square meter.

15. The absorbent article as claimed in clause 12, characterized in that the film and the non-woven material are bonded together with an adhesive.

16. The absorbent article as claimed in clause 12, characterized in that the film and the non-woven material are thermally bonded together.

17. The absorbent article as claimed in clause 12, characterized in that the film and the non-woven material are ultrasonically joined together.

.18. The absorbent article as claimed in clause 1, characterized in that the laminated outer cover further comprises a carded and bonded fabric.

19. The absorbent article as claimed in clause 1, characterized in that the absorbent article is selected from the group consisting of diapers, training pants, and garments for adult incontinence.

20. An absorbent article comprising a laminated outer cover, the laminated outer cover comprises a biodegradable stretched aliphatic-aromatic copolyester film, the film comprises filler particles and a copolyester comprising from about 10 mol% to about 30 mol% of terephthalic acid, from about 20 mol% to about 40 mol% adipic acid, from about 30 mol% to about 60 mol% 1,4-butanediol, and wherein the copolyester has an average molecular weight of weight from about 90,000 to about 160,000 daltons, and a number average molecular weight of from about 35,000 to about 70,000 daltons, and wherein the transition temperature of the copolyester glass is less than about 0 ° C. R E S U E An absorbent article comprising a laminated outer cover is described. The laminated outer shell comprises an aliphatic-aromatic copolyester film that includes a filler material. The aliphatic-aromatic copolyester films have a vapor transfer with adequate breathability and tensile strength properties while being essentially biodegradable.