ES2382791T3 - Biodegradable Copolyester Nonwoven Fabric - Google Patents

Abstract

A nonwoven fabric produced using an aliphatic copolyester as the filament material in a meltspinning process and apparatus including a filament extruder, spinneret and drawing unit having the capability of high velocity filament production. The fabric produced is biodegradable, soft, highly drapeable and has elastic properties. The degree of elasticity may be adjusted by varying filament production conditions and bonding parameters.

Description

Biodegradable Copolyester Nonwoven Fabric

Background of the invention

one.

 Field of the Invention

This invention relates to an improved fabric and a nonwoven web such as an adhesion spun web having a unique combination of properties hitherto unattainable with nonwoven fabrics made of nylon, polyester and polypropylene polymers or other polymers. The invention includes fabrics produced by the method of extrusion and stretching of filaments in an adhesion spinning process to produce nonwoven fabrics comprising an aliphatic-aromatic copolyester material. The fabrics produced have an exceptional draping capacity, resist wrinkling, are elastic, can be sterilized by gamma rays and are biodegradable in the right conditions.

2.

 Description of the state of the art

US Patent No. 5,545,371 issued to Fumin Lu, August 13, 1996, and US Patent No. 6,183,684 issued to Fumin Lu, February 6, 2001, describe a method and apparatus for producing nonwoven webs.

or cloth bands. The apparatus includes a polymer extruder and a spinning device in a molten state with a row having multiple spaced openings to provide a plurality of continuous filaments, a drawing unit that includes a longitudinally elongated groove strategically located at a predetermined distance below the row, a nozzle for providing an air supply within the stretching unit to create a stretching force on the filaments in the stretching unit and a mobile filament collection platform located below the groove of the stretching unit which collects the filaments forming them in a fabric or band or non-woven sheet.

The most common synthetic textile fibers used in nonwoven webs are made of nylon, polyester or polypropylene polymer and their copolymers. These polymers are all spinnable in the molten state and can be shaped into nonwoven fabrics using the apparatus described in US Patent 5,545,371 above. The polymers can be spun by adhesion, blown in the molten state, deposited in air, punched by needles, hydro-entangled or carded. While these procedures each have certain advantages in the production of fabrics with particular properties, fabrics often share certain limitations that restrict the applications of the fabric.

Brief Summary of the Invention

The purpose of the present invention is to provide a fabric that overcomes these limitations of the polymeric fabric of the prior art. Applicants have determined that using, for example, the apparatus and method described in US Patent 5,545,371 and a copolymer produced by Eastman Chemical Company of Kingsport, Tennessee described in US Patent 5,599,858 (which is incorporated into this application for reference purposes only) to produce the filaments, a non-woven fabric can be achieved that has an exceptional draping capacity, is elastic and can be stretched and relaxed in repeated cycles without failure or breakage. The new fabric can be bonded to various components including films, cellulosic material such as cotton, lyocell, polylactide polymers, wood pulp, wood fiber and paper and other natural fibers such as wool. The new fabric is totally biodegradable leaving only carbon dioxide and water when it decomposes completely. The finished fabric can be sterilized by gamma rays or electron beam. Various bonding technologies can be used in combination with the fabric including, but not limited to, point thermo bonding, resin bonding, needle punching, hydroentangling, air or ultrasonic bonding, radiofrequency, microwave or dielectric bonding.

The new fabric can also be formed using the apparatus and method described in US Patent No. 5,545,371 and an aliphatic-aromatic copolyester (hereinafter referred to as "AAEP") described in US Patent Nos. 5,446,079, 5,599 .858 and 6,020,393 (which are incorporated herein for reference purposes only and referred to herein as the AAPE Patents) to produce the filaments.

The new fabric is usually biodegradable in temperate coastal saltwater environments of shallow depth over a 15-20 week time interval. Similarly, similar results are seen in fresh water. Biodegradability in seawater is a highly desirable attribute for ecological reasons. It is well known that marine animals, such as sea turtles, ingest discarded plastic objects such as bags and packaging materials (confusing them with gelatinous fish) frequently resulting in the death of such animals.

The uses of the new fabric produced in the invention described herein include surgical clothes, sterile gowns and surgical packages, disposable hygienic components, durable products such as woven fabric substitutes, synthetic leather, cleaning products capable of being stretchable and elastic elements for such products. as disposable diapers and incontinent products where a good fit and shape are important aspects.

Detailed description of the invention

This invention relates to a product of a process and specifically to nonwoven fabrics prepared from a specific copolyester produced by Eastman Chemical Company of Kingsport, Tennessee which includes an aliphatic-aromatic copolyester described in US Patent 5,59,858 issued 4 from February 1997 to Charles Buchanan et al., entitled Aliphatic-Aromatic Copolyesters and Cellular Ester / polymer ”and specifically to the use of the aliphatic copolyester as the polymeric material used in a process and apparatus as described in US Patent 5,545. 371 (which is incorporated here for reference purposes only). In production according to the preferred embodiment, the adhesion spinning process using the apparatus described in Patent ‘371 above is carried out at a high speed of the filaments.

In addition, nonwoven fabrics can be produced from the aliphatic-aromatic copolyesters described in the AAPE patents as the polymer used in the process and apparatus described in the ‘371 patent.

The invention uses a polyester described in the AAPE patents. In a preferred embodiment, the AAPE is prepared and produced by Eastman Chemical Company of Kingsport, Tennessee and is marketed under the trademark EASTAR BIO ™ GP CoPolyester family. More specifically, AAPEs are essentially linear random copolyesters or branched and / or extended chain copolyesters thereof having recurring units of:

Y

where

R1 is chosen from one or more of the groups consisting of C2-C8 alkylene or oxyalkylene and the molar percentage of R1 is about 80 to 100; R3 is selected from one or more of the groups consisting of C2-C8 alkylene or oxyalkylene; C2-C8 alkylene or oxyalkylene substituted by one to four substituents independently selected from the group consisting of halo, C6-C10 aryl and C1-C4 alkoxy; C5-C12 cycloalkylene (for example, 1,4-cyclohexanedimethanol); C5-C12 cycloalkylene substituted with one to four substituents independently selected from the group consisting of halo, C6-C10 aryl and C1-C4 alkoxy; and the molar percentage of R3 is about 0 to 20; R2 is selected from one or more of the groups consisting of C2-C12 alkylene or oxyalkylene; C2-C12 alkylene or oxyalkylene substituted with one to four substituents independently selected from the group consisting of halo, C6-C10 aryl and C1-C4 alkoxy; C5-C10 cycloalkylene; C5-C10 cycloalkylene substituted with one to four substituents independently selected from the group consisting of halo, C6-C10 aryl and C1-C4 alkoxy; and the molar percentage of R2 is about 35 to 95; R4 is chosen from one or more of the groups consisting of C6-C10 aryl; C6-C10 aryl substituted with one to four substituents independently selected from the group consisting of halo, C6-C10 aryl and C1-C4 alkoxy; C5-C10 cycloalkylene; C5-C10 cycloalkylene substituted with one to four substituents independently selected from the group consisting of halo, C6-C10 aryl and C1-C4 alkoxy; and the molar percentage of R4 is about 5 to 65.

Preferred AAPEs are those wherein R1 is selected from C2-C8 alkylene and is present in an amount of approximately 90 to 100 mol%; R3 is present in an amount of about 0 to 10 mol%; R2 se

Choose from one or more of the groups consisting of C2-C8 alkylene or oxyalkylene and is present in an amount of about 35 to 95 mol%; and R4 is chosen from one or more of the groups consisting of C6-C10 aryl and is present in an amount of about 5 to 65 mol%. The most preferred AAPEs are those wherein R1 is selected from C2-C4 alkylene and is present in an amount of about 95 to 100 mol%; R3 is present in an amount of about 0 to 5 mol%; R2 is selected from one or more of the groups consisting of C2-C6 alkylene and is present in an amount of about 35 to 65 mol%; R4 is 1,4-disubstituted C6 aryl and is present in an amount of about 35 to 65 mol%.

As used herein, the terms "alkyl" and "alkylene" refer to straight or branched chain halves such as -CH2-CH2-CH2-CH2- and -CH2CH (x) -CH2-. The term "oxyalkylene" refers to alkylene chains containing 1 to 4 oxygen ether groups. The term "cycloalkylene" refers to any alkyl group containing a cycloalkyl moiety.

Other preferred compositions for these AAPE are those prepared from the following diols and diacids (or their polyester-forming derivatives) in the following molar percentage, based on 100 mol% of a diacid component and 100 mol% of a diol component:

(one)

 glutaric acid (approximately 30 to 75%); terephthalic acid (approximately 25 to 70%); 1,4-butanediol (approximately 90 to 100%); and diol modifier (approximately 0 to 10%).

(2)

 succinic acid (approximately 30 to 95%); terephthalic acid (approximately 5 to 70%); 1,4-butanediol (approximately 90 to 100%); and diol modifier (approximately 0 to 10%).

(3)

 adipic acid (approximately 30 to 75%); terephthalic acid (approximately 25 to 70%); 1,4-butanediol (approximately 90 to 100%); and diol modifier (approximately 0 to 10%).

The modifying diol is preferably chosen from 1,4-cyclohexanedimethanol, triethylene glycol, polyethylene glycol and neopentyl glycol. The most preferred AAPEs are linear, branched or extended chain copolyesters comprising about 50 to 60 moles% of adipic acid, about 40 to 50 moles% of terephthalic acid and at least 95 moles% of 1,4-butanediol. Even more preferably, adipic acid is present in an amount of about 55 to 60 mol%, terephthalic acid is present in an amount of about 40 to 45 mol% and at least 95 mol% of 1,4-butanediol. Such compositions are commercially supplied by Eastman Chemical Company of Kingsport, TN.

Specific examples of preferred AAPE include a tetramethylene poly (glutarate-co-terephthalate) containing (a) 50% glutaric acid / 50% terephthalic acid / 100% 1,4-butanediol, (b) 60% acid glutaric acid / 40% terephthalic acid / 100% 1,4-butanediol or (c) 40% glutaric acid / 60% terephthalic acid / 100% 1,4-butanediol; a poly (tetramethylene succinate-co-terephthalate) containing (a) 85% succinic acid / 15% terephthalic acid / 100% 1,4-butanediol or (b) 70% succinic acid / 30% acid terephthalic / 100% 1,4-butanediol; a poly (ethylene succinate-co-terephthalate) containing 70% succinic acid / 30% terephthalic acid / 100% ethylene glycol; and a poly (tetramethylene adipate-co-terephthalate) containing 85% adipic acid / 15% terephthalic acid / 100% 1,4-butanediol.

Conveniently, the AAPE has approximately 10 to 1000 recurring units and preferably approximately 15 to 600 recurring units. Preferably, the AAPE has an inherent viscosity of about 0.4 to 2.0 dl / g, more preferably about 0.7 to 1.4, measured at a temperature of 25 ° C for a sample of 0.5 g in 100 ml of a 60/40 solution by weight of phenol / tetrachloroethane.

The AAPE of the present invention may also contain a branching agent. The weight percentage for the branching agent is about 0.01 to 10%, preferably 0.1 to 1.0% by weight, based on the total weight percentage of the AAPE.

The branching agent preferably has a weight average molecular weight of about 50 to 5,000, more specifically about 92 to 3,000, and a functionality of about 3 to 6. The branching agent may be a polyol having 3 to 6 hydroxyl groups, a polycarboxylic acid having 3 or 4 carboxyl groups or a hydroxy acid having a total of 3 to 6 hydroxyl and carboxyl groups.

Representative low molecular weight polyols that function as branching agents include glycerol, trimethylolpropane, 1,2,4-butanedriol, pentaerythrilol, 1,2,6-hexanotriol, sorbitol, 1,1,4,4 tetrakyl (hydroxymethyl) cyclohexane, tris (2-hydroxyethyl) isocyanurate and dipentaerythritol. Particular examples of branching agents of the higher molecular weight polyols (MW 400-3000) are the triols derived by condensation of alkylene oxide having 2 to 3 carbon atoms, such as ethylene oxide and propylene oxide, with polyol initiators.

Representative polycarboxylic acids that can be used as branching agents include glycerol, trimethylolpropane, 1,2,4-butanethriol, pentaerythrilol, 1,2,6-hexanotriol, sorbitol, 1,1,4,4

tetrakis (hydroxymethyl) cyclohexane, tris (2-hydroxyethyl) isocyanurate and dipentaerythritol. Particular examples of branching agents of the higher molecular weight polyols (MW 400-3000) are the triols derived by condensation of alkylene oxide having 2 to 3 carbon atoms, such as ethylene oxide and propylene oxide, with polyol initiators.

Representative hydroxy acids such as branching agents include malic acid, citric acid, tartaric acid, 3-hydroxyglutaric acid, muric acid, trihydroxyglutaric acid and 4- (beta-hydroxyethyl) phthalic acid. Said hydroxy acids contain a combination of 3 or more hydroxyl and carboxyl groups.

Especially preferred branching agents include trimellitic acid, trimesic acid, pentaerythritol, trimethylolpropane and 1,2,4-butanethriol.

An example of branched AAPE of the present invention is poly (tetramethylene adipate-co-terephthalate) containing 100 mol% 1,4-butanediol, 43 mol% terephthalic acid and 57 mol% adipic acid and being branched with 0 , 5% by weight of pentaerythritol. This copolymer is produced when dimethyl adipate, dimethyl terephthalate, pentaerythritol and 1,4-butanediol are heated at 190 ° C for 1 hour, at 200 ° C for 2 hours, at 210 ° C for 1 hour and then at 250 ° C for 1, 5 hours under vacuum in the presence of 100 ppm of Ti initially present as Ti (OiPr) 4. The copolyester is usually pelletized after its formation for use in extrusion foaming.

Another branched AAPE of the present invention is poly (tetramethylene adipate-co-terephthalate) containing 100 mol% 1,4-butanediol, 43 mol% terephthalic acid and 57 mol% adipic acid and being branched with 0.3 % by weight of pyromellitic dianhydride. This copolymer is produced by reactive extrusion of poly (tetramethylene adipate-co-terephthalate) with pyromellitic dianhydride using an extruder.

The AAPE of the present invention may also contain a chain extender. Examples of chain extenders are divinyl ethers as described in US Patent No. 5,817,721 and incorporated herein for reference purposes only. Preferred divinyl ethers are 1,4-butanediol divinyl ether, 1,5-hexanediol divinyl ether and 1,4-cyclohexanedimethanol divinyl ether. The weight percentage ranges for the chain extender are 0.01 to 5%, preferably 0.3 to 2.5% by weight, based on the total weight percentage of the AAPE.

The preparation of polyesters and copolyesters is well known in the art (US Patent No. 2,012,267). Such reactions are normally carried out at temperatures of 150 ° C to 300 ° C in the presence of polycondensation catalysts such as titanium tetrachloride, manganese diacetate, antimony oxide, dibutyltin diacetate, zinc chloride or combinations thereof. The catalysts are generally used in amounts between 10 and 1000 ppm, based on the total weight of the reactants. For the purposes of the present invention, a representative aliphatic polyester is the condensation product of dimethyl glutarate and 1,6-hexanediol. This polyester, poly (hexamethylene glutarate), is produced when dimethyl glutarate and 1,6-hexanediol are heated at approximately 210 ° C for 4 hours and then at 260 ° C for 1.5 hours under vacuum in the presence of 100 ppm of Ti . A representative aliphatic-aromatic copolyester is poly (tetramethylene glutarate-co-terephthalate) containing 30 mol% terephthalate. This polyester is produced when dimethyl glutarate, dimethyl terephthalate and 1,4-butanediol are heated at 200 ° C for 1 hour and then at 245 ° C for 0.9 hours under vacuum in the presence of 100 ppm of Ti initially present as Ti ( OiPr) 4.

The adhesion spun web produced with the Eastman EASTAR BIO GP CoPolyester material for the filaments produces a fabric that has exceptional draping capability along with an inherent resistance to wrinkle formation at room temperature. The fabric achieves smoothness without smoothing or grating and is very comfortable to use. Additives and pigments can be incorporated into the fabrics so produced. Finishing treatments can also modify the aesthetics to the touch.

The fabric produced provides a sheet that is elastic since it can be stretched and then relaxed and stretched again from repeated cycles without defects. The fleeces produced from this material exhibit high elasticity without any breakage. After changing the conditions of the spinning process, the degree of elasticity can be adapted to specific applications of the fabric. Similarly, proper selection of process conditions may vary the characteristic of surface friction from a chewy touch to a soft cotton texture. In addition, the selection of the process conditions may also vary the surface characteristics from a bundle appearance of sticky filaments to a bundle free appearance of sticky filaments.

The fabric produced by this invention can be bonded to many components and substrates including, but not limited to, films, fabrics, nonwovens, sheets or metallic layers and papers. The fabric can be coated by extrusion with various polymers and formulations, including itself. The fabric is suitable for binding to cellulosic fibers and other natural fibers and biodegradable polymers such as polylactides. Other spunbond fibrous structures can also be prepared by mixing in pellets or in the molten state of the copolyester of

this invention with other polymers, including other biodegradable or compostable polymers.

Very importantly, the fabric produced by the invention in the adhesion spinning process will degrade in an environment of garbage leaving only carbon dioxide and water when it decomposes completely. When kept away from garbage environments, durable nonwoven fabrics are possible.

The copolyester described herein can be joined by adhesion to other fibrous materials in the production line, to prepare multilayer products.

Fabrics and composite materials that are produced with this family of materials can be sterilized by gamma rays.

Various bonding techniques can be used in conjunction with this fabric. The joining of the fabric can be, for example, by calendering point bonding, resin bonding, needle punching, air or ultrasonic bonding, radiofrequency, microwave or dielectrically bonded. Binding of the finished fabric to other materials may include hot melt adhesive bonding, ultrasonic bonding, radiofrequency bonding, microwave bonding and dielectric bonding, hot air bonding or radiant bonding and other lamination techniques. The low crystalline melting point of this polymer (approximately 108 °) improves high speed bonding in manufacturing processes.

The fabric can be thermally contracted around an object or shape to produce an elastic fabric that adapts to the shape while retaining elastic properties, strength and toughness.

The fabric produced by this invention can be derived from filamentous forms of multiple components including, but not limited to, one or more of the components constituted by Eastman's biodegradable copolyester. Multi-component filament styles such as side-by-side, sheath / core, island-in-the-sea can be employed, regardless of the cross-sectional shape of the filaments (eg, round, tape, hollow, trilobal and other high surface geometries).

This invention can be further illustrated by the following examples of preferred embodiments thereof, although it is to be understood that these examples are included for illustrative purposes only and should not be considered as limiting the scope of the invention, unless it is specified in another way.

In accordance with these and other objects that will become apparent below, the present invention will now be described with particular reference to the accompanying drawings.

Preferred mode of the invention

Fabrics were produced by the process and the adhesion spinning machine described in US Patent No.

5,545,371 and in US Patent No. 6,183,684 in the following examples:

EXAMPLE ONE

The Eastar BIO ™ GP copolyester pellets were dried at 45 ° C for 6 hours to achieve the moisture content of the resin of approximately 300 ppm before being fed to the extruder. The temperature of the extruder and the rotary press brake was set at 195º C. The width of the wetted area of the row was 500 mm with holes of 0.35 mm in diameter. The total number of holes was 2,016. The extruded filaments were dragged down by a dragging device that has a longitudinal groove 100 mm longer than the wetted area of the row. Compressed air was supplied at 35 psi to the groove and the extracted filaments exiting the groove were deposited on a moving belt with a suction box below the wire. The melt production was dosed by a pair of metering pumps at a speed of 0.5 g per hole per minute (ghm). The band formed on the belt was moved at 15 m per minute and thermally bonded at a temperature of 85 ° C by means of a calender. The fabric thus produced was rolled into a roller. The filament before calendering had a denier of 1.3 and the fabric had a basis weight of 130 g per m2. Adhesion spun fabric exhibited good appearance, elastic properties and good handling capacity without cracking or handling noise.

From the DSC test results, certain qualities of the fabric can be observed. The first DSC curve (which reflects the properties of the fabric) showed a bimodal characteristic with the main endothermic melting point at 120º C. The second scan (which erases the characteristics of the fabric and reflects the properties of the polymer) showed a point of Endothermic fusion in a relatively broad but simple way at 108º C. The first DSC scan estimated a crystallinity of 29%. Cloth spun adhesion fabrics were also successfully produced with higher production and with both higher and lower spinning speeds.

EXAMPLE TWO

The same machine and the same procedure as were used in example one were adapted for Eastar BIO ™ GP resin, except that the melting temperature used was 205 ° C and the compressed air pressure was increased to 45 psig. The filaments produced at 0.5 ghm had a denier of 1.0 and the fabrics were obtained at 30 m / min with a basis weight of 70 g / m2. Fabrics with a base weight of 40 g / m2 were also produced at a linear speed of 40 m / min.

By changing the conditions, adhesion spun fabrics were produced that have a basis weight of 10-17 g / m2, also significantly higher yields. All these bands exhibited good structural integrity.

Some of the advantages of this fabric composition include:

a) The fabrics produced have an exceptional draping capacity along with an inherent resistance to the formation of wrinkles at room temperature. The fabric achieves softness without luster or shine and is of comfortable use. b) The sheet is elastic since it can be stretched and then relaxed and stretched again in repeated cycles without any failure. The fleeces produced from this material exhibit high elasticity without breakage. Through the modification of the spinning process conditions, the degree of elasticity can be adapted to specific applications of the fabric. Similarly, a suitable selection of the process conditions can vary the frictional characteristics on the surface from a chewy touch to a soft cotton texture and from a viscous appearance to a viscosity free one. c) The fabric can be attached to many component substrates made of, but not limited to, wool, cotton, lyocell, wood pulp, polylactide polymers, polycaprolactone, paper and other compostable / biodegradable polymers. The fabric can also be laminated to films and other polyesters. d) The material will degrade in an environment of compost or garbage leaving only carbon dioxide, water and trace minerals when it decomposes completely but durable or long life outside such environments or environments. e) Fabrics and composite materials that are produced with this family of materials can be sterilized by electronic beam or gamma rays. f) It can be joined by means of most of the available technologies itself or to other materials in single or multiple layers. Various connection technologies can be used in connection with this fabric. The joining of the fabric can be, for example, by heat, by calendering by points, with resin, by air, by hot melt adhesive, by hydro-entangling, by needle punching, by ultrasound, by radiofrequency, by microwave and by dielectric means, as well as by binding fibers and by molding. The low crystalline melting point of this polymer improves high speed bonding in manufacturing processes. The products are usually comfortable when handled or used. g) The fabric can be heat contracted around an object or shape to produce an elastic fabric that adapts to the shape while retaining elastic properties, strength and toughness.

The use of the fabric may include, but not limited to, the following:

a) surgical clothing, plus other barrier fabrics such as for protection against pesticides, etc; b) sterile gowns and components of surgical packages; c) disposable hygienic components including, but not limited to, diapers, compresses and incontinence clothing, tampons, feminine sanitary napkins, disposable underwear and bedding, and other body fluid containment vehicles, disposable bath clothes or other limited life products, etc; d) non-woven substitutes for knitted and knitted fabrics without compromising their biodegradability in their use, such as pillowcases, upholstery, insulation, curtains, clothing, gloves and some industrial items; e) agricultural, horticultural and geotextile fabrics and meshes for various applications, including weed and erosion control, planting mats and containers, thermoformed flower pots, tree and shrub covers, plant treatment supply systems, etc. ; f) comfortable and extensible substrates for synthetic leathers, vinyl, suede and other luxurious fabrics of high value; g) cleaning products that require a durable and tear-resistant fabric that is able to stretch substantially before breaking but still absorbs and retains dust or other particulate matter; in other embodiments, adhesion spun fabrics can be used for the supply of chemicals and cleaning and disinfectants, medical / cosmetic skin treatments, furniture waxes and the like; h) any of the above together with support or coating of film or other layers to form unique structures; i) combinations of the above products with a film of the same family of resins, formed or laminated to a non-woven fabric; j) combinations of the above products with a film formed or laminated to a nonwoven fabric; k) fabrics produced from filamentous forms of multiple components that include one or more of the components constituted by this biodegradable CoPET. Such multi-component filamentous styles may include, but not limited to, side-to-side, sheath / core, island-in-the-sea styles regardless of the cross-sectional shape of the filaments (eg, round, ribbons, trilovals,

gaps); l) fabrics produced from these multi-filament forms. This fabric construction is a mixture of two or more different types of filaments and where at least one of these filamentous constituents is constituted by this biodegradable coPET. Such multi-filament styles can be combined with the multi-component shapes of the previous k point; and m) elastic elements for products such as disposable diapers, adult incontinence products, as well as durable items where elastic properties are needed.

The cloth produced exhibits a shrinking property after exposure to heat. The resulting contracted fabric retains the elastic characteristics of the fabric before contraction without becoming fragile. The material contracts to conform to the shape of the surface of the object around which it is wrapped. The shrinkage can be as high as 90% of the original dimensions of the sheet, while the total available shrinkage can be predetermined through the selection of the processing conditions under which the base sheet is produced. The main determinants of contraction in the adhesion spinning process are the speed of the filaments and the conditions of heat bonding. Also effective are effective rapid cooling and temperature control in the threading line.

As the fabric sheet is contracted, the fibrous structure resembles the contraction of the sheet with the dimensions, so that the porosity of the sheet decreases, the barrier properties of the sheet increase together with the base weight, but it is preserved the elastic nature. Conventional polyester fabrics that contract under the influence of heat usually become fragile and rigid; The novelty of this invention lies in the retention of flexibility and elasticity. In addition, the limitation of the contraction allows the production of elastic articles in predetermined dimensions and with extension / recovery characteristics. By means of a controllable thermal contraction, the pore size can be controlled and a disposable filter can be produced.

These properties are of a particular application in the manufacture of articles that are initially manufactured in one dimension and then dimensionally altered through the use of heat to a final product form. Such application is not only useful in the production of disposable diapers and training briefs, adult incontinence products, clothing, feminine shaped sanitary napkins, but also applicable to packaging materials that require insulation, barrier protection with ability to breathe or adapt to shape such as, but not limited to, gowns and surgical clothing sterilizable by electronic beam, bandages, support fabrics, gloves, car covers, mattress beds and beds, food contact material, labels for packaging and adaptable wine containers pro contraction.

Normally, the fabric of the present invention is biodegradable in shallow warm coastal salt water environments within a 15-20 week time frame. The trial consisted of suspending a sample of the fabric of a fixed rope tied to a breakwater in Lighthouse Point, Florida, so that the sample remained below the medium level at low tide, verifying that after 15 weeks the sample had degraded to a thin very thin veil that broke after being recovered from the water.

An object of this invention is to provide an improved fabric that is nonwoven and has a unique combination of unreachable properties in other nonwoven fabrics using a special copolyester currently produced and supplied by Eastman Chemical Company under the trademark EASTAR BIO GP CoPOLYESTER in a method and apparatus for the production of nonwoven fabric, spun by adhesion.

Another object of this invention is to provide a nonwoven fabric that can be spun by adhesion and that provides elastic qualities, thermal bonding qualities, that is biodegradable and that can be sterilized by gamma rays.

The present invention has been shown and described here in what is considered to be the most practical and preferred embodiment. However, it should be understood that modifications thereof may be made within the scope of the invention and that the person skilled in the art may deduce obvious modifications.

Claims (8)

one.

Method for the production of a biodegradable nonwoven fabric comprising the steps of:

extrude a plurality of continuous filaments from a row; stretching said filaments by a stretching unit located at a predetermined distance below the row to provide a force on said filaments by application of air to the stretching unit; depositing said filaments on a collection surface to form a nonwoven fabric; use an aliphatic-aromatic copolyester in said extruder as the material for the filaments.

2.

Method according to claim 1, wherein the aliphatic-aromatic copolyester has recurring units of:

Y where R1 is chosen from one or more of the groups consisting of C2-C8 alkylene or oxyalkylene and the molar percentage of R1 is about 80 to 100; R3 is selected from one or more of the groups consisting of C2-C8 alkylene or oxyalkylene; C2-C8 alkylene or oxyalkylene substituted by one to four substituents independently selected from the group consisting of halo, C6-C10 aryl and C1-C4 alkoxy; C5-C12 cycloalkylene (for example, 1,4-cyclohexanedimethanol); C5-C12 cycloalkylene substituted with one to four substituents independently selected from the group consisting of halo, C6-C10 aryl and C1-C4 alkoxy; and the molar percentage of R3 is about 0 to 20; R2 is selected from one or more of the groups consisting of C2-C12 alkylene or oxyalkylene; C2-C12 alkylene or oxyalkylene substituted with one to four substituents independently selected from the group consisting of halo, C6-C10 aryl and C1-C4 alkoxy; C5-C10 cycloalkylene; C5-C10 cycloalkylene substituted with one to four substituents independently selected from the group consisting of halo, C6-C10 aryl and C1-C4 alkoxy; and the molar percentage of R2 is about 35 to 95; R4 is chosen from one or more of the groups consisting of C6-C10 aryl; C6-C10 aryl substituted with one to four substituents independently selected from the group consisting of halo, C6-C10 aryl and C1-C4 alkoxy; C5-C10 cycloalkylene; C5-C10 cycloalkylene substituted with one to four substituents independently selected from the group consisting of halo, C6-C10 aryl and C1-C4 alkoxy; and the molar percentage of R4 is about 5 to 65.

3.

Method according to claim 1 or 2, comprising the steps of:

use two or more rows or dies of molten spinning; introduce one or more layers of other fibrous materials on the surface; deposit said filaments from one or more rows, stratified on the surface to create a fabric non woven; Y use the aliphatic copolyester as at least one of the materials that are extruded for the filament.

Four.

Method according to claim 1, 2 or 3, wherein a high speed of said filaments is established.

5.

Method according to claim 1, 2 or 3, wherein additives or pigments are added to the extruder.

6.

Method according to claim 1, 2 or 3, wherein the thermal contraction is controlled.

7.

A nonwoven fabric produced by a method according to any one of claims 1 to 6.

8.

Use of a non-woven fabric according to claim 7 for the production of clothing, diapers, training briefs, incontinence products in adults, feminine sanitary napkins, surgical clothes, bandage packaging materials, food contact products , support fabrics, mattress covers, sanitary napkins.