AU2007229313B2 - Absorbent article - Google Patents

Abstract

The invention provides a disposable personal care absorbent article comprising a layered structure, the layered structure comprising an absorbent structure disposed in between a body facing liquid-permeable top sheet and a liquid-impermeable back sheet, wherein the top and back sheets are biodegradable, and wherein the disposable personal care absorbent article has plant seed incorporated therein.

Description

WO 2007/106929 PCT/AU2007/000323 ABSORBENT ARTICLE Field of the invention The present invention relates to absorbent articles, and in particular to disposable personal 5 care absorbent articles. Background of the invention Disposable personal care absorbent articles are used in a diverse array of applications. For example, in the infant and childcare areas disposable diapers and training pants have generally replaced re-useable cloth absorbent products. Other examples of disposable 10 absorbent articles include panty liners, bed liners, bed pan liners, adult incontinence products, and surgeon's underwear. A typical disposable personal care absorbent article generally comprises a layered structure made up from an absorbent structure disposed in between a body facing liquid-permeable top sheet and a liquid-impermeable back sheet. Articles that are to be worn by a user 15 typically also include some type of fastening system for fitting the product onto the wearer. During use, the personal care absorbent articles are typically subjected to one or more urine and/or other body exudate insults. The body facing liquid-permeable top sheet enables body fluids to pass through into the absorbent structure. The absorbent structure functions to contain the discharged materials and to also isolate these materials from the 20 body of a user, and often from the user's garments and bedding. The liquid-impermeable back sheet serves to prevent any absorbed liquid from passing through the absorbent article and soiling adjacent articles such as clothing, bedding and the like. The back sheet also generally provides strength and handling capability to the article so that it retains its integrity during use. Durability of the absorbent article is particularly important in the 25 infant and childcare applications. To afford the requisite properties, top and back sheets have traditionally been made from polyolefins such as polyethylene or polypropylene. Conventional disposable personal care absorbent articles have to date been generally well received by consumers. However, with both government and consumers becoming more WO 2007/106929 PCT/AU2007/000323 -2 environmentally aware, there is now a growing concern over the disposal of such articles. In particular, many of the components that make up conventional absorbent articles are non-biodegradable. Accordingly, when the articles are disposed of by means such as flushing down a toilet or placement in a municipal waste stream to be buried in landfill, 5 they can remain substantially intact and persist in the environment for many years. Considering that an average family having 2 children using disposable diapers up until the children are fully toilet trained can produce up to 10 tonnes of used diapers, which as a collective occupies about 2-4 % of landfill space, the disposal of these articles within an ever growing population is clearly a mounting problem. 10 In order to reduce the environmental impact resulting from the disposal of personal care absorbent articles, one or more non-biodegradable polymer components which make up the articles may be manufactured from a biodegradable polymer. For example, US 6,569,990 discloses a biodegradable polyhydroxyalkanoate (PHA) copolymer for producing components used in the manufacture of disposable diapers. 15 However, despite the application of biodegradable polymers in the manufacture of personal care absorbent articles, the shear volume of disposed articles will continue to be a burden on conventional municipal waste stream facilities. In particular, municipal sewage treatment and landfill facilities around the world are experiencing difficulties in processing the amount of consumer waste that is currently being generated. 20 Accordingly, there remains an opportunity to develop a disposable personal care absorbent article which can promote a reduction in the negative environmental impact associated with the disposal of such articles. Summary of the invention The present invention provides a disposable personal care absorbent article comprising a 25 layered structure, the layered structure comprising an absorbent structure disposed in between a body facing liquid-permeable top sheet and a liquid-impermeable back sheet, wherein the top and back sheets are biodegradable, and wherein the disposable personal care absorbent article has plant seed incorporated therein.

WO 2007/106929 PCT/AU2007/000323 -3 By providing the combination of biodegradable components, an absorbent structure and plant seed, the disposable personal care absorbent article in accordance with the invention provides a particularly effective growth medium for a plant. In particular, the absorbent structure can function as a water retention aid, and body exudates can function as a 5 fertiliser to advantageously facilitate growth of the plant. Once buried, the top and back sheets are designed to readily degrade enabling the plant seed to germinate and propagate into a plant. The absorbent articles of the invention therefore become a valuable resource after use rather than just waste. Accordingly, after using the absorbent article in accordance with the invention consumers 10 will have good reason to dispose of the article by burying it, in for example a garden bed, rather than disposing of it in a municipal waste stream. Alternatively, used articles could be disposed of in a municipal waste stream and then recovered by local government as a valuable resource for revegetating denuded land. Instead of being directly buried in soil, the absorbent article in accordance with the 15 invention can also be disposed of in an environmentally friendly manner by earthworm composting (vermicomposting). During vermicomposting the worms are very active in their search for suitable food and will rapidly penetrate all parts of the absorbent article and thereby facilitate exposing the article components/body exudates to soil microbes. As part of the vermicomposting process earthworms advantageously produce castings which, 20 along with the composted article and now unconfined plant seed, can be applied to a garden within the germination period of the plant seed to promote seedling growth. To more readily distinguish the absorbent articles of the invention from conventional non seed carrying and non-biodegradable absorbent articles, they will preferably be uniquely coloured and/or labelled. 25 Detailed description of the invention As used herein, the expression "personal care absorbent article" refers to devices which absorb and contain body exudates, and more specifically to devices which are placed against or in proximity to the body of a person to absorb and contain the various exudates WO 2007/106929 PCT/AU2007/000323 -4 discharged from the body. The term "disposable" is used herein to describe personal care absorbent articles that are not intended to be laundered or otherwise restored or reused as an absorbent article (ie. they are intended to be discarded after a single use). The top and back sheets used in accordance with the invention may conveniently be 5 formed from one or more biodegradable polymers. Those skilled in the art will appreciate that the term "biodegradable" does not have a universal definition. For avoidance of any doubt, the term "biodegradable" used herein in association with the term "polymer" is intended to mean a polymer material that meets the. biodegradability criteria specified in ASTM 6400 or EN 13432. Thus, a polymer is considered to be biodegradable if, upon 10 exposure to a composting environment, 90 wt.% of it disintegrates into particles having an average size of less than 2mm within 12 weeks, and after 6 months at least 60 wt.% of it, in the case of ASTM 6400, or at least 90 wt.% of it, in the case of EN 13432, has degraded into carbon dioxide and/or water. Preferably, a biodegradable polymer used in accordance with the invention meets the more stringent biodegradability criterion set forth in EN 15 13432. Other materials that are referred to herein as being "biodegradable" are also intended to be materials that meet the biodegradability criteria specified in ASTM 6400 or EN 13432. The absorbent article of the invention can conveniently be constructed in a similar manner to conventional disposable personal care absorbent articles. In particular, the absorbent 20 structure, and the biodegradable top and back sheet components of the article can simply be substituted for the equivalent components in conventional absorbent articles. As will be discussed in more detail below, the plant seed may be readily incorporated within the absorbent article during its manufacture. The absorbent article in accordance with the invention may be readily manufactured in the 25 form of infant and childcare products such as diapers and training pants, bed liners, bed pan liners, feminine hygiene products such as panty liners, adult incontinence products, surgeon's underwear and the like. Preferably, the absorbent article is provided in the form of a diaper or training pants.

WO 2007/106929 PCT/AU2007/000323 -5 As the body facing top sheet used in the invention will generally be in contact with a person's skin, it will preferably be compliant, soft feeling and non-irritating to skin. The body facing top sheet in effect serves as a barrier between the user of the article and the absorbent structure. The top sheet is liquid-permeable to enable body fluid to pass 5 through into the absorbent structure. The top sheet is preferably adapted to minimise transfer of body fluid from the absorbent structure back through the top sheet in the direction of the users body (ie. adapted to minimise rewet). Techniques for adapting top sheets to minimise rewet are well known in the art and can be readily applied to the top sheets used in accordance with the invention. Such techniques include coating of the top 10 sheet with a hydrophobic surfactant on the upper (body facing) side and coating the adjacent side with a hydrophilic surfactant. The top sheet used in accordance with the invention can derive its liquid-permeable properties by being microperforated through needle perforation, embossing, thermoforming or through being mineral (e.g. calcium carbonate) filled and stretched 15 during manufacture to create micropores using techniques well known in the art. The top sheet may also derive its liquid-permeable properties by virtue of being made from a porous non-woven or spun bonded fabric. Preferably, the liquid-permeable properties of the top sheet are designed to maximise the acquisition and distribution of liquid through into the absorbent structure. Such a top sheet 20 is often referred to in the art as an acquisition and distribution layer (ADL). A preferred top sheet is in the form of about a 30 to 50 gsm, more preferably about a 40 gsm, non-woven or spun bonded sheet. An important feature of the invention is that the top and back sheets are biodegradable. The biodegradability of the sheets not only enables the absorbent article to degrade upon 25 being buried, but as a result of the degradation it also allows plant seed, that may be initially confined by the non-degraded top and/or back sheet, to geminate and propagate through the article to reach the surface. Degradation of the sheets also exposes the WO 2007/106929 PCT/AU2007/000323 -6 absorbent structure, and therefore any body exudates, to the plant root system and to soil borne bacteria that facilitate degradation of these components. The top and back sheets are preferably entirely (ie 100%) biodegradable. In order to impart biodegradable character to the top and back sheets, it is preferred that they are made 5 substantially from one or more biodegradable polymers. Suitable biodegradable polymers that may be used to make the top sheet include, but are not limited to, polycaprolactone (PCL) and starch blends thereof, as sold by Biograde Ltd; polylactic acid (PLA) and starch blends thereof; polybutylene succinate (PBS) and starch 10 blends thereof, as sold by Showa (Japan) and under the trade name EnPolTM by Ire Chemical Ltd (Korea), preferably the PBS is blended with 20 to 50 weight % thermoplastic starch; aromatic-aliphatic copolyesters and starch blends thereof, as sold under the trade name EcoflexTM by BASF and EnPolTM by Ire Chemical Ltd (Korea), preferably those copolyesters derived from 1,4 -butanediol, terephthalic acid and adipic acid (ie PBAT 15 type), preferably the terephthalic acid content in the copolyesters is 42-45 mol% (with regard to the dicarboxylic monomers.); a blend of thermoplastic starch (TPS), aliphatic polyester (e.g. PCL) and plasticiser(s) (e.g. glycerol and sorbitol) such as Biograde TM BF sold by Biograde Ltd (Australia); polybutylene adipate (PBA) and starch blends thereof, as sold under the trade name EnPolTM by Ire Chemical Ltd (Korea). Preferred EnPolTM 20 grades include, but are not limited to, G8060, G4260 and G4560. Preferably, the top sheet is made from PLA. PLA is biodegradable in accordance with EN13432 and ASTM 6400, and can be readily converted into non-woven sheets by dry-, air-, wet-, spunmelt-, laying systems. PLA top sheets can provide excellent resilience, excellent body fluid transport and distribution through into an absorbent structure, 25 excellent breathability, excellent wet strength, and superior handling/touch qualities compared with the performance properties of polymers used in the manufacture of conventional top sheets. Preferably, the PLA top sheet is provided in the form of a non-woven sheet. Examples of commercially available PLA non-woven sheets include those sold under the name of WO 2007/106929 PCT/AU2007/000323 -7 PiaoanTM PLA spunlace nonwoven by Henan Piaoan High-tech Stock Co (China), TerramacTM by Unitika (Japan), IngeoTM PLA non-wovens by Far Eastern Textile (FET) (Taiwan); LACTRONTM by Kanebo (Japan), LACEATM by Mitsui Toatsu (Japan), DEPOSATM by Fiberweb (France), and EcoPLATM by Cargill Dow Polymers (United 5 States of America). The absorbent article in accordance with the invention comprises a liquid-impermeable back sheet. Those skilled in the art will appreciate that the function of a back sheet in such an article is to prevent absorbed body fluid from passing through the article and soiling adjacent articles such as clothing, bedding and the like. Although back sheets are in effect 10 designed to prevent liquid such as urine passing through the absorbent article, when the articles are in a form such as a diaper, liquid and vapour-impermeable back sheets can make a wearer feel hot and uncomfortable. To improve the wearability of such articles, the back sheets are generally designed to be water-impermeable but vapour-permeable, or as it is more commonly known in the art "breathable". Back sheets are also often designed such 15 that the surface facing away from the body has a cloth-like feel to provide added comfort to the user. Preferably, the back sheet is made from a thermoplastic starch-based polymer, more preferably from a thermoplastic starch-based aliphatic polyester. A suitable thermoplastic starch-based polymer includes, but is not limited to, a polymer composition comprising 20 starch, plasticiser and a polyester such as polycaprolactone (PCL). Back sheets made from a thermoplastic starch based polymer have been found to exhibit an advantageous silky feel and texture as well as excellent breathability compared with that of conventional back sheets made from polyolefins such as polyethylene or polypropylene. A preferred thermoplastic starch-based aliphatic polyester for use in the manufacture of the 25 back sheet is sold under the trade name BiogradeTM BF by Biograde Ltd (Australia). BiogradeTM BF is a fully biodegradable plastic based on a blend of thermoplastic starch (TPS), aliphatic polyester (PCL) and natural plasticisers (glycerol and sorbitol). Preferred physical and mechanical properties of the thermoplastic starch-based polymer for use in the manufacture of the back sheet include a melt flow index of about 2 g/10 min WO 2007/106929 PCT/AU2007/000323 -8 (2.16 kg/ 190*C) (ASTM D-1238), a density of about 1.05 g/cm3 (ASTM D4883), a tensile strength at yield of greater than about 10 MPa (ASTM D-883), a tensile strength at break of greater than about 10 MPa% ASTM D-883, and an elongation at break of greater than about 200 % (ASTM D-883). 5 A cloth like feel may also be provided to the absorbent article to afford further comfort to a user. This may be achieved by bonding an additional lightweight (ie about 15-18 gms) PLA spun-melt-spun (SMS) layer onto the outermost side of the top and/or back sheets. The absorbent structure used in accordance with the invention serves to absorb bodily fluids. The absorbent structure may be of a type used in conventional absorbent articles. 10 Typically the absorbent structure will be made from an absorbent member that is generally compressible, readily shaped, non-irritating to a user of the article and capable of absorbing and retaining bodily fluids such as urine and other body exudates. The absorbent structure may be provided in a wide variety of sizes and shapes, the detail of which will vary dependent upon the application of the absorbent article. When the 15 absorbent article is in the form of a diaper, the absorbent structure will generally be provided in a "T", rectangular, or hourglass shape. The absorbent structure may be manufactured from a diverse array of liquid absorbent materials commonly used in diapers and other absorbent articles. Suitable absorbent materials include, but are not limited to, comminuted wood pulp which is generally 20 referred to as airfelt, cotton wool, creped cellulose wadding, sphagnum moss, carboxy methyl-cellulose, meltblown polymers including coform, chemically stiffened, modified or cross-linked cellulosic fibres, tissue, including tissue wraps and tissue laminates, absorbent foams, absorbent sponges, super absorbent polymers (SAP), cellulose fluff, protein gel, wood pulp from softwood trees such as spruce and pine, sodium polyacrylate contained in 25 the fluffed wood pulp, absorbent gelling materials, or combinations thereof. The configuration and construction of the absorbent structure within the article will vary depending upon the intended application of the article. For example, the absorbent structure may have varying caliper zones, a hydrophilic gradient, a super absorbent gradient, lower average density and lower average basis weight acquisition zones, or may WO 2007/106929 PCT/AU2007/000323 -9 comprise one or more layers. Furthermore, the size and absorbent capacity of the absorbent structure may also be varied to accommodate a body fluid insult from different users such as infants through to adults. Preferably, the absorbent structure comprises a super absorbent polymer such as sodium 5 polyacrylate. Sodium polyacrylate is commonly used in conventional absorbent articles and is also used as a water-retaining gel in agricultural applications. This polymer has the unique property of being able to absorb several hundred times its weight in water, release the stored water and then reabsorb water in a cyclic fashion for several years. Accordingly, super absorbent polymers such as sodium polyacrylate can serve not only as 10 an effective absorbent medium in the article of the invention, but also as a water retention agent to facilitate the growth of a plant which germinates from the plant seed contained in the absorbent article. If desired, the absorbent structure may be made from a biodegradable material. Suitable biodegradable materials that may be used in the manufacture of the absorbent structure 15 include, but are not limited to, airfelt, carboxy-methyl-cellulose (CMC), cotton wool, sphagnum moss, cellulose fluff, protein gel, wood pulp from softwood trees such as spruce and pine. An important feature of the invention is that the absorbent article incorporates plant seed therein. In order for the plant seed to develop into a plant, the seed will of course be 20 located in the absorbent article such that plant growth would not be prevented by confinement caused by a non-biodegradable component of the article. For this reason, it is preferred that structural features of the absorbent article, other than the absorbent structure, are made from biodegradable materials. Although possibly desirable in some cases, it is not particularly important that the absorbent structure be made from a biodegradable 25 material. In particular, materials generally used to manufacture the absorbent structures are not likely to restrict seed germination or plant growth even if the plant seed were dispersed throughout the structure. To the contrary, a non-biodegradable material such as sodium polyacrylate is commonly used in agricultural applications, and by acting as a water retention aid can in fact facilitate growth of the plant.

WO 2007/106929 PCT/AU2007/000323 - 10 The plant seed may be incorporated within the absorbent article by any suitable means. For example, the plant seed may be contained within the absorbent structure, or held in place by means used to fix the components of the article together such as stitching and/or the use of an adhesive. 5 As a result of the top and back sheets of the absorbent article being biodegradable, these components can readily degrade upon being buried underground. By virtue of this degradation, a plant derived from the plant seed incorporated within the absorbent article can readily propagate from the buried article to reach the surface. Advantageously, soiled absorbent articles will generally comprise bodily exudates that 10 facilitate growth of the plant. In particular, bodily exudates such as urine provide a rich source of nitrogen and ions such as calcium and magnesium for the initial stages of plant growth, and faecal matter can function as a source of manure to assist with the longer term growth of the plant. Microflora/bacteria present in faecal matter have also been found to facilitate biodegradation of the article. 15 The absorbent article in accordance with the invention will generally comprise a number of plant seeds. The plant seed is preferably selected such that its typical germination period is equal to or greater than the time taken for the top and/or back sheets to degrade sufficiently after being buried underground to enable a plant to propagate from the article and reach the surface. The time taken for the top and back sheets to degrade after being buried 20 underground will vary depending upon factors such as the composition of the sheets, and the temperature, type and hydration level of the soil, but will typically be in the order of about 4 to 6 weeks. Those skilled in the art will appreciate that numerous varieties of plant seed may be used in accordance with the invention. Suitable plant seed includes, but is not limited to, turf or 25 grass seed and Australian native plant seed such as Heath Banksia (Banksia ericifolia), Weeping Red Bottlebrush (Callistemon viminallis), Red and Green Kangaroo Paw (Anigosanthos manglesii), New South Wales Waratah (Tlopea speciosissima), Stuart's Desert Pea (Clianthus formosus), Lemon Scented Eucalyptus (Eucalyptus citriodora), and WO 2007/106929 PCT/AU2007/000323 -11 Honey Myrtle Paperbark (Melaleuca armillaris) seed. A combination of plant seed varieties may be incorporated within the personal care absorbent article. The components of the absorbent article may be held together using techniques known in the art such as by stitching and/or by using adhesive materials such as hot melt glue 5 (adhesive). Preferably, any material used in fixing components of the absorbent article to each other are biodegradable. For example, biodegradable stitching threads made from PLA, cotton, Rayon and combinations thereof, and/or biodegradable adhesives such as a hot melt glue based on polycaprolactone may be used. Polycaprolactone based hot melt glues are particularly suited for use in fixing components 10 of the absorbent article to each other as they are generally effective at adhering to biodegradable polymers that may be used in accordance with the invention. Such hot melt glues are also generally characterised by a low melting temperature and a low melt viscosity which allows the glues to be readily applied and penetrate into the components being fixed to promote a strong bond. The polycaprolactone based hot melt glues are 15 particularly suited for use with temperature sensitive substrates such as polylactic acid non-woven top sheets that may be used in accordance with the invention. Suitable polycaprolactone based hot melt glues include, but are not limited to, those sold under the tradename CAPATm 6000 Series by Solvay. The absorbent article in accordance with the invention is preferably constructed in the form 20 of a diaper. In this case, the article will also be constructed with other features that are common to conventional diapers. For example, the absorbent article may comprise elasticised components in the waist and leg regions to improve both comfort and fit of the diaper to the user. Where an elastic component is used in the absorbent article of the invention, it is preferably biodegradable. Suitable biodegradable elastic materials include, 25 but are not limited to, polyurethane polyester foam and natural rubber. The absorbent article may also comprise barrier leg cuffs which, in conjunction with the elasticised leg regions, serve to prevent leakage of body exudates from the article when in use. One or more leg cuffs may be provided for each leg region of the article. The leg cuffs will WO 2007/106929 PCT/AU2007/000323 - 12 generally be liquid impermeable and vapour permeable, and preferably made from the same materials as the back sheet referred to above. In the form of a diaper, the absorbent article may also comprise fixation tabs or tapes that are used to hold the back facing section to the stomach facing section of the article when in 5 use. Those tabs or tapes used in conventional diapers may also be used with the absorbent article of the invention. However, it is preferred that the tabs or tapes are biodegradable. In this case, the tabs or tapes will preferably be made from PLA. Where an adhesive material is used on the tabs or tapes to facilitate fixing the back facing section to the stomach facing section, the adhesive material is also preferably biodegradable, for example 10 an adhesive based on a rubber latex. A common practice with the use of conventional diapers is that once the diaper has been soiled it is sealed in a small plastic bag, that may be optionally scented, which is then disposed of. Where such a plastic bag is to be used in conjunction an absorbent article in accordance with the invention, the plastic bag should also be biodegradable. There are 15 numerous biodegradable plastic bags that are commercially available that would be suitable for use for this purpose. Preferred biodegradable plastic bags are those sold under the name BiogradeTM by Biograde Ltd, Australia. The depth at which a soiled absorbent article should be buried will in part be determined by the type of seed contained within the article. Other factors such as hygiene will also 20 generally need to be considered. Brief description of the drawing A preferred embodiment of the invention will now be illustrated by way of example only with reference to the accompanying drawing in which Figure 1 shows an absorbent article in accordance with the invention in the form of a diaper. 25 Detailed description of the drawing Figure 1 shows a disposable personal care absorbent article in accordance with the invention in the form of a diaper (10). The diaper (10) comprises an absorbent structure WO 2007/106929 PCT/AU2007/000323 - 13 (20) disposed in between a body facing liquid-permeable top sheet (not labelled) and a liquid-impermeable back sheet (not labelled). The top sheet is made from spun-bonded 40 gsm polylactic acid sheet, and the back sheet is made from a plasticised thermoplastic starch-polycaprolactone polymer (BiogradeTM BF). Optionally, an additional lightweight 5 17 gsm PLA SMS layer (not shown) can be bonded to the outermost surface of the top and/or back sheets to afford a cloth like feel to the diaper. The absorbent structure (20) comprises cellulose fibre and sodium polyacrylate in about a 50:50 weight percent ratio. The absorbent structure (20) comprises plant seeds (30) distributed there through. The diaper has back facing ear panels (40a) and stomach facing ear panels (40b). The fixing 10 tabs (50) can be used to fix the diaper around the waist of a user by connecting to regions on or around the stomach facing ear panels (40b). The tabs (50) are made from PLA film. A biodegradable rubber latex adhesive (not shown) is used to promote connection of the tabs (50) to a region on or near the stomach facing ear panels (40b). The diaper comprises waist elasticised regions (60a), and leg elasticised regions (60b). The elastic material used 15 in these regions is Lycra or natural rubber. The diaper (10) also comprises one or more barrier leg cuffs (70). The barrier leg cuffs (70) are made from a plasticised thermoplastic starch-polycaprolactone polymer (BiogradeTM BF). A polycaprolactone based hot melt adhesive was used for fixing the components of the diaper (10) together. The invention will now be described with reference to the following example which 20 illustrates a preferred embodiment of the invention. However, it is to be understood that the particularity of the following description is not to supersede the generality of the preceding description of the invention. Example A diaper was assembled using a polycaprolactone based hot melt adhesive to bond together 25 an absorbent structure comprising sodium polyacrylate/cellulose fibre (50:50 weight percent) disposed in between a spun-bonded 40 gsm polylactic acid body facing top sheet and a thermoplastic starch-polycaprolactone back sheet (BiogradeTM BF). An additional lightweight 17 gsm PLA SMS layer was bonded to the outermost surface of the top and back sheets to afford a cloth like feel to the diaper. Plant seed (Red Bottlebrush) was WO 2007/106929 PCT/AU2007/000323 - 14 incorporated within the absorbent structure of the diaper during construction. The diaper was also constructed with a Lycra waistband, natural rubber elasticised leg region, natural rubber elasticised barrier leg cuffs made from a plasticised thermoplastic starch polycaprolactone polymer (BiogradeTM BF), and PLA fixing tabs having a biodegradable 5 rubber latex adhesive disposed thereon. The diaper was constructed in a size suitable to fit a 2 year old toddler. In use, the diaper was found to perform satisfactorily in terms of urine retention, leak resistance, comfort and breathability. After being soiled, the diaper was buried for 12 weeks in standard garden soil and watered nightly. After 12 weeks the site was inspected and the majority of the 10 diaper had disintegrated into barely recognisable fragments. However, the absorbent structure was still discernible as a swollen gel. The seeds contained within the diaper were found to germinate and propagate into seedlings after about 4 to 6 weeks. Throughout this specification and the claims which follow, unless the context requires otherwise, the word "comprise", and variations such as "comprises" and "comprising", will 15 be understood to imply the inclusion of a stated integer or step or group of integers or steps but not the exclusion of any other integer or step or group of integers or steps. The reference in this specification to any prior publication (or information derived from it), or to any matter which is known, is not, and should not be taken as an acknowledgment or admission or any form of suggestion that that prior publication (or information derived 20 from it) or known matter forms part of the common general knowledge in the field of endeavour to which this specification relates.

Claims (10)

1. A disposable personal care absorbent article comprising a layered structure, the layered structure comprising an absorbent structure disposed in between a body 5 facing liquid-permeable top sheet and a liquid-impermeable back sheet, wherein the top and back sheets are biodegradable, and wherein the disposable personal care absorbent article has plant seed incorporated therein.

2. The disposable personal care absorbent article according to claim 1, wherein the top sheet is a porous non-woven or spun bonded fabric. 10

3. The disposable personal care absorbent article according to claim 2, wherein the porous non-woven or spun bonded fabric has a weight of about 30 to 50 gsm.

4. The disposable personal care absorbent article according to any one of claims 1 to 3, wherein the top sheet is manufactured from polycaprolactone, polylactic acid, polybutylene succinate, aromatic-aliphatic copolyesters, polybutylene adipate, or 15 starch blends thereof.

5. The disposable personal care absorbent article according to any one of claims 1 to 4, wherein the back sheet is manufactured from a thermoplastic polymer composition comprising starch, plasticiser and a polyester.

6. The disposable personal care absorbent article according to any one of claims 1 to 20 5, wherein the absorbent structure is manufactured from comminuted wood pulp, cotton wool, creped cellulose wadding, sphagnum moss, carboxy-methyl-cellulose, meltblown polymers, absorbent foams, absorbent sponges, protein gel, sodium polyacrylate, or combinations thereof.

7. The disposable personal care absorbent article according to any one of claims 1 to 25 6, wherein the plant seed is incorporated within the absorbent structure. WO 2007/106929 PCT/AU2007/000323 - 16

8. The disposable personal care absorbent article according to any one of claims 1 to 7, wherein components of the article are fixed to each other with a polycaprolactone based hot melt adhesive.

9. The disposable personal care absorbent article according to any one of claims 1 to 8 5 which is in the form of a diaper, training pants, bed liner, bed pan liner, panty liner, adult incontinence product, or surgeon's underwear.

10. The disposable personal care absorbent article according to any one of claims 1 to 9, wherein the top sheet and back sheet meet the biodegradability criteria specified in EN 13432. 10