WO2009090380A1

WO2009090380A1 - Apparatus for storing and dispensing a water dispersible substance

Info

Publication number: WO2009090380A1
Application number: PCT/GB2009/000094
Authority: WO
Inventors: Mark Collins
Original assignee: Concentrated Solutions Limited
Priority date: 2008-01-15
Filing date: 2009-01-15
Publication date: 2009-07-23
Also published as: GB2456523A; GB201013707D0; GB0800731D0

Abstract

The invention provides an apparatus for storing and dispensing a water dispersible substance, the apparatus comprising an outer container (2) and an inner container (10); wherein the outer container has an inlet and an outlet (8); the inner container has one or more openings through which water may pass and containing one or more dosage units comprising a water-swellable or water- soluble bioipolymer, which biopolymer has encapsulated therein a water dispersible substance; and the outer and inner containers are configured such that in use, when the inner container is disposed inside the outer container, water may be passed through the outer and inner containers to elute the water dispersible substance from the polymer thereby to provide a solution of the substance.

Description

APPARATUS FOR STORING AND DISPENSING A WATER DISPERSIBLE SUBSTANCE

This invention relates to apparatus for storing and dispensing a water dispersible substance.

Background of the Invention

Corrosive substances such as acids and alkalis generally require special precautions when being transported and cannot easily be transported using normal mail services. The fairly robust handling that they are likely to receive if transported in the normal mail means that bottles or sachets or other containers typically used for carrying liquids may be broken or ruptured thereby releasing their contents.

Summary of the Invention

The present invention provides a means of transporting concentrated forms of water dispersible substances in solid form in mailing containers rather than in bottles, drums and like containers. The water dispersible substance, which may be in a concentrated liquid form, is encapsulated in a protective biopolymer, thereby rendering it easier to package and transport using normal mailing systems. On receiving the product, the customer can form an aqueous solution of the water dispersible substance by eluting the substance from the polymer encapsulant with water using an apparatus as described herein.

Accordingly, in a first aspect, the invention provides an apparatus for storing and dispensing a water dispersible substance, the apparatus comprising an outer container and an inner container; wherein the outer container has an inlet and an outlet; the inner container has one or more openings through which water may pass and contains one or more dosage units comprising a water-swellable or water- soluble biopolymer, which biopolymer has encapsulated therein a water dispersible substance; and the outer and inner containers are configured such that in use, when the inner container is disposed inside the outer container, water may be passed through the outer and inner containers to elute the water-soluble substance from the polymer thereby to provide a solution of the water dispersible substance.

The term "water dispersible substance" as used herein encompasses substances that are soluble in water as well as substances that are insoluble or sparingly soluble in water but can be dispersed in a finely divided form in water, for example as a suspension or emulsion.

The water-swellable or water-soluble polymer has encapsulated therein a water- dispersible substance. The dosage units can take the form of capsules in which the water dispersible substance is surrounded by an outer skin of polymer or can take the form of a polymer matrix in which the water dispersible substance is distributed.

The capsules can be microcapsules (e.g. they can have diameter of less than 1 mm) or they can have a minimum dimension of greater than or equal to 1 mm.

When the dosage units are in the form of a matrix, they can have a minimum dimension of less than lmm or they can have a minimum dimension of equal to or greater than 1 mm. For example, they can have a minimum dimension of at least 1 mm (for example at least 1.5 mm or at least 2 mm or at least 2.5 mm) and a maximum dimension of at least mm (for example at least 1.5 mm or at least 2 mm or at least 2.5 mm or at least 3 mm or at least 3.5 or at least 4 mm).

In one preferred embodiment, the dosage units have a maximum dimension (e.g. diameter) of at least 10 mm, or at least 15 mm, for example in the range 15-20 mm. In this embodiment, the dosage units may have a minimum dimension (e.g. thickness) of 1 to 5 mm, e.g. 1.5 to 3 mm.

In one embodiment, the dosage units are in the form of discs or biscuits.

The term "biopolymer" as used herein refers to a polymer which is derived at least in part from a renewable organic non-petroleum and non-coal source material. Thus the biopolymer may be formed entirely from monomer units ("bio- monomers") derived from a renewable organic non-petroleum and non-coal source material, or it can be formed from a mixture of bio-monomers or non-bio- monomers. The biopolymer may also consist of a mixture of one or more polymers formed entirely from bio-monomer units and one or more polymers formed from monomers derived from non-renewable (e.g. petroleum or coal) sources. Unless the context indicates otherwise, the term "biopolymer" as used herein embraces both polymers formed entirely from renewable organic sources or polymers or mixtures of polymers containing monomers derived from both renewable and non-renewable sources.

In one embodiment, at least 50% (e.g. at least 60%, or at least 70%, or at least 80%, or at least 90%, or at least 95%, or at least 99%, for example 100%) of the monomer units in the biopolymer are derived from renewable organic non- petroleum and non-coal source materials.

The organic source material is preferably an organic source that can be grown or cropped on a regular basis, for example at intervals of one day or less, or one week or less, or one month or less, or three months or less, or six months or less, or on an annual, biennial or triennial basis, or at intervals of up to ten years or up to twenty years, or up to thirty years or up to forty years or up to fifty years..

More preferably, the organic source material is derived from an organic source that can be cropped on an annual or part annual basis.

Examples of organic source materials or feedstocks are plant crops such as cereals, grasses, maize, sugar beet and sugar cane.

Examples of cereals include wheat, barley, oats and rice.

Particular examples of organic source materials include sugar, potatoes (e.g. potato skins), maize, corn stover, grasses, wheat and rice straws, and bagasse.

One preferred biopolymer is polylactide (PLA) which is a biodegradable, thermoplastic, aliphatic polyester. Polylactide can be produced from a variety of renewal feedstocks, for example by the fermentation of agricultural by-products such as corn starch or other starch-rich substances like potato skins, maize, sugar or wheat.

Polylactides are produced by a process that comprises bacterial fermentation of the feedstock to produce lactic acid. The lactic acid is then oligomerized and then catalytically dimerized to make a monomer which can then be subjected to polymerization to give the PLA.

Several forms of polylactide exist. Poly-L-lactide (PLLA) results from the polymerization of L,L-lactide (also known as L-lactide). PLLA has a crystallinity of around 37%, a glass transition temperature between 50-80° C and a melting temperature between 173-178° C.

The polymerization of a racemic mixture L- and D-lactides leads to the synthesis of poly-DL-lactide (PDLLA) which is not crystalline but amorphous.

Polylactides are available commercially from Nature Works LLC, a wholly owned subsidiary of Cargill Corporation, Toyota (Japan), Hycail (The Netherlands) and Galactic (Belgium).

Polylactides can be prepared by a variety of methods including the processes described in WO 93/15127 (Cargill) and WO 01/38284 (Cargill Dow LLC) and references cited therein.

The polylactide biopolymers may be homopolymers of copolymers with non-lactic acid monomers such as glycolic acid. Examples of copolymers include lactide glycolide copolymers, lactide caprolactone copolymers, lactide cyclic carbonate polymers and lactide derived poly(ester amides).

Other examples of biopolymers include: ■ Chitin-based biopolymers such as chitosan (see for example WO 01/68714 to Cargill, Inc.); ^■ Gelling hemicelluloses such as the oxidatively gelled hemicelluloses and arabinoxylans disclosed in WO 01/49320 (Cambridge Biopolymers);

^■ Plastarch Material (a biodegradable thermoplastic material formed from modified cornstarch); and ■ Polyhydroxyalkanoates (e.g. Biopol) such as poly-3-hydroxybutyrate, poly-

4-hydroxybutyrate (P4HB), polyhydroxyvalerate (PHV), polyhydroxyhexanoate (PHH), polyhydroxyoctanoate (PHO) and their copolymers

The biopolymer may be a water soluble biopolymer but preferably it is insoluble.

When the biopolymer is insoluble, it will typically be swellable to allow water to penetrate the matrix or capsule so as to elute the water dispersible substance.

The biopolymer may be mixed with or form part of a copolymer with a non- biopolymer material. For example, the biopolymer may be mixed with a polymer as described in any of WO 00/06610, WO 00/06533, WO 00/06658, WO 01/40874 and WO 2007/012860.

When the biopolymer is mixed with or copolymerised with a non-biopolymer or monomer of a non-biopolymer, one particular polymer is formed by the polymerisation of a dienyl quaternary amine monomer either alone or in the presence of a co-monomer. For example, the dienyl quaternary amine monomer may be a monomer as described in WO 2007/012860 (Novel Polymer Solutions).

Where the biopolymer or biopolymer copolymer is intended to be insoluble in water, but water-swellable, it is typically a crosslinked polymer. Crosslinking can be accomplished in any of a variety of ways well known to the skilled person. For example, Crosslinking can be carried out under oxidative conditions, or thermal conditions, by means of an initiator or by means of radiation, e.g. UV radiation, or a combination thereof. The particular method of crosslinking will be selected according to the nature of the monomer being used and the mechanism by which it undergoes polymerisation. Where the biopolymer is mixed with a non-biopolymer or the biopolymer monomer is polymerised with a co-monomer which is not derived from a renewable organic source, particularly examples of non-biopolymers are those formed by the cyclopolymerisation of a dienyl quaternary amine monomer as described in WO 2007/012860. More particularly, the polymers are those formed by the cyclopolymerisation of quaternary diallylamine monomers. The diallylamine monomers can be derived from cyclic amines such as piperidine and piperidine derivatives or from acyclic amines such as long chain hydrocarbyl amines. A monomer may have a single dienyl quaternary amine group present or may have two or more dienyl quaternary amine groups present, each linked by a suitable linking chain such as a hydrocarbon chain. Where two or more such dienyl quaternary amine groups are present, they can form cross links when polymerised to form a three dimensional gel network.

When it is required that the polymer should be water soluble, the polymer will typically not be crosslinked and will usually have only a single dienyl quaternary amine group present. One example of a monomer from which a soluble polymer can be formed is N,N-diallylpiperidinium halide, e.g. N,N-diallypiperidinium bromide.

The water dispersible substance encapsulated by the polymer can be any of a variety of such substances but, in one embodiment, the water dispersible substance is a liquid, and in particular a liquid concentrate. Thus, the dosage unit comprises a matrix of water swellable or water soluble polymer within which are dispersed pockets of encapsulated water dispersible substance.

The liquid can be a corrosive substance such as an acid or alkali or bleaches as well as any of a wide ranger of other water dispersible substances.

Other examples of water dispersible substances that can be encapsulated include a wide range of commercial, domestic and retail cleaning products.

The polymer is selected such that it is compatible with the water dispersible substance that it encapsulates, i.e. it is not degraded or dissolved by the substance. The dosage units may contain a predetermined or metered amount of the water dispersible substance. Thus, for example, the dosage units may each be of a predetermined substantially uniform weight. Alternatively, the dosage units may vary in weight and content.

In one preferred embodiment, the water dispersible substance is an acid such as nitric acid or sulphuric acid or is a bleach.

The dosage units can be formed by simply mixing (e.g. shear mixing) the monomer and water dispersible substance, dividing the mixture into portions of a desired volume and then polymerising the monomer.

The mixture may be divided into portions by using a pipette to measure out predetermined volumes and deposit the predetermined volume of mixture onto an inert surface or into a mould followed by curing of the mixture.

By encapsulating the water dispersible substance to form a dry product, it can be transported with greater security and safety in ordinary mailing packaging and does not need to be contained within drums or bottle.

A customer can be supplied with a kit comprising the outer and inner containers with the encapsulated water dispersible substance present within the water soluble container. The customer can then assemble the apparatus of the invention by placing the inner container within the outer container, removing any closure means present on the inner container and then pouring a required volume of water into the outer and inner containers. The water penetrates the inner container and either dissolves or swells the biopolymer to release the water dispersible substance and form a solution (or a more dilute solution if the concentrate is already in solution form) which can then be collected in a suitable receptacle.

If a customer has previously been supplied with a kit comprising both the inner and outer containers, then he or she may subsequently only be provided with the inner container containing the dispensing units. Once used, the inner containers may be sent back to the manufacturer for recharging or recycling.

It will be appreciated from the foregoing that the inner container functions as a cartridge which may be refilled or recycled after use. For convenience, the inner container may be referred to in this application as a cartridge.

The outer container can be of solid construction, i.e. the outer container holds its shape without the need for support, or it can take the form of a bag-like structure.

When the outer container is of solid construction, it is preferably formed from a plastics material, and most preferably is moulded (e.g. injection moulded) from a plastics material. The outer container may be substantially rigid, or the plastics material may have a degree of flexibility or resilience.

The outer container may take any of a wide variety of shapes provided that it can accommodate the inner container.

In one embodiment, the outer container is of substantially tubular construction having an inlet opening at one end (which in use is the upper end) into which water can be poured and an outlet opening at the opposing end (which in use is the lower end) through which water or eluted water-soluble substrate can pass out of the container. The tubular construction may be of circular or non-circular (e.g. rectangular) cross section.

In one embodiment, the outer container is of flattened rectangular cross section, a shape which is particularly suitable for transporting in mailing containers.

In one embodiment, the outer container is in the form of a funnel and the inner container is configured to sit within the funnel.

The funnel may have a substantially tubular upper region and a tapering lower portion. The inner container may be configured so that it can be seated in the tapering portion of the funnel. The tubular upper region may have substantially parallel side walls and may be, for example, of circular cross section or rectangular cross section (e.g. flattened rectangular cross section).

The tapering portion of the funnel may terminate in a pipe or spout to enable a solution of eluted water-soluble substance to be dispensed from the container in a controlled manner.

The outlet (e.g. the outlet of the tapering portion of the funnel, or the pipe or spout) may be provided with a valve or tap to control the flow of liquid therethrough.

In another embodiment, the outer container takes the form of a bag. The bag has an opening through which water can be produced. The opening is preferably arranged to be closable, for example by means of folding or by means of a drawstring around the neck of the bag.

The bag is typically provided with an outlet in addition to the inlet. The outlet can take the form of perforations (e.g. micro-perforations) in the bag wall. Thus, for example, the bag can be formed from a permeable material, e.g. a permeable plastics material.

The inner container may have an opening into which water can be poured and at least one other opening through which water or a solution of the eluted substrate may exit the inner container. Preferably the inner container has a plurality of openings through which the water or solution of eluted substance may exit the container.

In one embodiment, the plurality of openings takes the form of a plurality of perforations in the container wall.

In another embodiment, the plurality of opening takes the form of gaps between the fibres or strands in a mesh, for example a woven mesh.

The inner container can be of solid construction, i.e. the container holds its shape without the need for support, or it can take the form of a bag-like structure. When the inner container is of solid construction, it is preferably formed from a plasties material, and most preferably is mounded (e.g. injection moulded) from a plastics material. The inner container may be substantially rigid, or the plastics material may have a degree of flexibility or resilience.

The inner container may take any of a wide variety of shapes provided that it can be seated within the outer container.

In one embodiment, the inner container is of substantially tubular construction having an inlet opening at one end (in use the upper end) into which water can be poured and a plurality of exit openings through which water or a solution of eluted substance can exit the container. The exit openings can be present at the end (which in use is the lower end) opposed to the inlet opening. For example, the lower end of the inner container can be provided with a filter which retains water swellable polymer but allows the passage therethrough of the eluted water dispersible substance. The filter can be of the filter frit type or can be a filter of the fibrous type or can simply comprise an array of holes that are sufficiently large to permit water or eluted water-soluble substance to flow freely therethrough whilst preventing the passage of any particulate matter with a minimum dimension (e.g. diameter) of, for example, 0.1 mm, or 0.5 mm or lmm or 5 mm or 10 mm.

In addition to the filter, the inner container may be provided a plurality of perforations on a side wall thereof. When the inner container is of substantially tubular form, the side walls may have an array of perforations extending around its circumference. The perforations are preferably evenly spaced.

When the inner container is of tubular construction, it may have a circular or non- circular cross section. For example, it may have an elliptical cross section or a polygonal (e.g. regular polygonal) cross section. In one embodiment, the inner container is of tubular construction and has a circular cross section. In another embodiment the inner container is of tubular construction and has a rectangular cross section, for example a flattened rectangular cross section. A flattened rectangular cross section is particularly suited for transporting in a mailing container. In another embodiment, the inner container can take the form of a bag, for example a bag resembling a teabag and formed from a porous material or mesh. The dosage units containing the encapsulated water dispersible substance are contained within the bag. In this embodiment, water and eluted water-soluble substance may flow freely in and out of perforations in the bag.

The inner container preferably has means for closing the container when the container is not is use or is in transit. For example, when inner container is of solid construction, the means for closing the container can comprise a lid, plug or a sliding closure.

In one embodiment, the means for closing the container is a lid. The lid may be fully or partially detachable from the container. For example, the lid can be hingedly attached to the container. In an alternative, the lid may be fully detachable. The lid may be secured in place by means of a snap fit or "pop off/pop on" arrangement.

The means for closing the container serves to retain the portions of encapsulated water-soluble substance in place when in transit.

As indicated above, the outer and inner containers may be provided to a customer in the form of a kit for assembly to for the apparatus of the invention.

In one embodiment therefore, the invention provides the apparatus in kit form.

In another embodiment, the invention provides the apparatus in assembled form.

In a further aspect, the invention provides a product containing a mailing container within which is disposed the apparatus of the invention in kit form or assembled form, and more preferably in kit form. The mailing container may take the form of a box, e.g. a box formed from cardboard or plastics or a combination thereof.

In a still further aspect, the invention provides a mailing container within which is disposed an inner container as hereinbefore defined, the inner container containing a plurality of dosage units as hereinbefore defined. In another aspect, the invention provides a method for preparing an aqueous solution of a water dispersible substance, which method comprises passing water through an apparatus as hereinbefore defined so as to swell or dissolve the encapsulating polymer and elute the water dispersible substance.

The invention will now be illustrated in more detail (but not limited) by reference to the specific embodiment shown in the drawings

Brief Description of the Drawings

Figure 1 is a schematic partial side sectional elevation of an apparatus according to one embodiment of the invention.

Figure 2 is a schematic side sectional view of the outer container of the apparatus of Figure 1.

Figure 3 is a schematic side view of the inner container or cartridge of the apparatus of Figure 1, but with a lid in place.

Figure 4 is a side sectional elevation through an inner container of slightly differing shape to the inner container of Figure 1.

Figure 5 illustrates a mailing box containing a used and unused cartridge from the apparatus of Figures 1 to 4.

Figure 6 illustrates an apparatus according to a second embodiment of the invention.

Detailed Description of the Invention

As shown in Figures 1 to 3, an apparatus according to one embodiment of the invention comprises an outer container 2 in the form of a funnel formed from a plastics material. The funnel has a generally cylindrical upper portion 4 which is open at its upper end, and a lower tapering portion 6 leading to an outlet or spout 8.

Seated inside the outer container 2 is an inner container or cartridge 10 which is of generally cylindrical form and is formed from a moulded plastics material. The cartridge 10 has a filter 12 at its lower end and an array of perforations 14 around the circumference of its side wall. As shown in Figure 3, the cartridge has a snap fit lid 16 which is left in place during transit and is removed when the apparatus is used.

Contained within the cartridge is a plurality of discs or "biscuits" 18 which may stacked one on top of another (as shown in Figure 4) or stacked loosely within the container (as shown in Figures 1 and 3). The biscuits are formed from a water swellable biopolymer and in particular a polylactide polymer of the type described above.

Encapsulated within the biopolymer is a water dispersible liquid substance or a concentrated solution of a water dispersible substance (for example EDTA or a salt thereof). The biscuits are formed by shear mixing a monomer with the liquid substance or concentrate to form a liquid mass which is then is divided into portions, for example by means of a pipette or by pouring into a mould. The individual portions are then irradiated with UV light to bring about polymerisation of the monomer. By way of example, the resulting biscuits or discs can be approximately 2 mm in depth and about 19 mm in diameter.

By encapsulating the liquid substance or concentrate in a biopolymer matrix, the substance or concentrate is converted into a dry form that can readily be transported using a suitable mailing container.

The customer may be presented with a kit consisting of the outer container and cartridge, wherein the cartridge contains the dosage units. The customer may then assemble the apparatus by placing the cartridge inside the outer container so that the lower end of the cartridge is seated just above the tapering portion of the funnel. The lid 16 is then removed and a desired amount of water is poured into the open topped cartridge container. Where the biscuits are formed from a water soluble material, the action of the water is to dissolve the biscuits, thereby forming a solution of polymer and water dispersible substance which then passes through the filter 12 and out through the spout 8 where it can be collected in a suitable receptacle. Alternatively, if the polymer is a water-insoluble but water-swellable biopolymer, the biopolymer will swell to allow penetration of the water, thereby allowing the water dispersible substance to be eluted through the filter and out through the spout 8. In this case, any polymer residue is retained by the filter as shown in Figure 1. Once used, the cartridge may be sent back to the manufacturer for refilling or recycling.

Figure 5 shows a typical transport box or mailer that can be used to mail new cartridges to the customer. The new cartridge is wrapped, for example, in cellophane or a similar waterproof material. The box also has space for accommodating spent cartridges for return to the manufacturer.

An advantage of the apparatus shown in Figures 1 to 5 is that it allows corrosive substances such as acids and alkalis to be packaged and transported by post or courier in a safe manner without the need for containment within bottles or drums or more complex packaging.

The apparatus shown in Figures 1 to 5 is of a solid construction, i.e. the outer container and cartridge are both self supporting. In an alternative arrangement, as shown in Figure 6, the outer container can take the form of a permeable bag 102 having a draw string 104 around its neck and a locking toggle 106 to allow the bag to be sealed in a closed condition. Within the outer bag 102 is an inner diffuser bag 108 within which are contained the biscuits 110 of polymer encapsulated water dispersible substance. In this embodiment, the draw string is released and water is poured into the open mouth of the outer bag. The water penetrates the inner diffuser bag 108 eluting the water dispersible substance, with the result that a more diluted solution of the substance can then pass through the walls of the outer permeable bag and into a suitable receptacle.

The embodiments illustrated in the Figures represent merely several ways of putting the invention into effect and it will readily be apparent that numerous modifications and alterations may be made to the specific embodiment shown without departing from the principles underlying the invention. All such modifications and alterations are intended to be embraced by this application.

Claims

1. Apparatus for storing and dispensing a water dispersible substance, the apparatus comprising an outer container and an inner container; wherein the outer container has an inlet and an outlet; the inner container has one or more openings through which water may pass and containing one or more dosage units comprising a water- swellable or water-soluble biopolymer, the biopolymer being a polymer which is derived at least in part from a renewable organic non-petroleum and non-coal source material which polymer has encapsulated therein a water-dispersible substance; and the outer and inner containers are configured such that in use, when the inner container is disposed inside the outer container, water may be passed through the outer and inner containers to elute the water-soluble substance from the polymer thereby to provide a solution of the water dispersible substance.

2. Apparatus according to claim 1 wherein the dosage units are in the form of capsules in which the water dispersible substance is surrounded by an outer skin of biopolymer.

3. Apparatus according to claim 1 wherein the dosage units take the form of a polymer matrix in which the water dispersible substance is dispersed.

4. Apparatus according to claim 1 wherein the dosage units are in the form of discs or biscuits.

5. Apparatus according to any one of the preceding claims wherein the biopolymer is substantially insoluble in water but is swellable to allow water to penetrate the matrix or capsule so as to elute the water dispersible substance.

6. Apparatus according to any one of the preceding claims wherein the water dispersible substance is a liquid concentrate.

7. Apparatus according to claim 6 wherein the liquid concentrate is a corrosive substance such as an acid or alkali or bleaches.

8. Apparatus according to claim 7 wherein the corrosive substance is an acid.

9. Apparatus according to any one of the preceding claims wherein the outer container is of substantially tubular construction having an inlet opening at one end (which in use is the upper end) into which water can be poured and an outlet opening at the opposing end (which in use is the lower end) through which water or eluted water dispersible substrate can pass out of the container.

10. Apparatus according to claim 9 wherein the outer container is in the form of a funnel and the inner container is configured to sit within the funnel.

11. Apparatus according to claim 10 wherein the funnel has a substantially tubular upper region and a tapering lower portion.

12. Apparatus according to claim 11 wherein the tapering portion of the funnel terminates in a pipe or spout to enable a solution of eluted water dispersible substance to be dispensed from the container in a controlled manner.

13. Apparatus according to claim 12 wherein the outlet (e.g. the outlet of the tapering portion of the funnel, or the pipe or spout) is provided with a valve or tap to control the flow of liquid therethrough.

14. Apparatus according to any one of claims 1 to 8 wherein the outer container takes the form of a bag.

15. Apparatus according to claim 14 wherein the bag is closable by means of a drawstring around the neck of the bag.

16. Apparatus according to claim 14 or 15 wherein the bag is formed from a permeable material, e.g. a permeable plastics material.

17. Apparatus according to any one of the preceding claims wherein the inner container has an opening into which water can be poured and at least one other opening through which water or a solution of the eluted substrate may exit the inner container.

18. Apparatus according to claim 17 wherein the inner container has a plurality of openings through which the water or solution of eluted substance may exit the container.

19. Apparatus according to claim 18 wherein the plurality of openings takes the form of a plurality of perforations in the container wall.

20. Apparatus according to any one of the preceding claims wherein the inner container is of substantially tubular construction having an inlet opening at one end (in use the upper end) into which water can be poured and a plurality of exit openings through which water or a solution of eluted substance can exit the container.

21. Apparatus according to claim 20 wherein the lower end of the inner container is provided with a filter which retains water swellable polymer but allows the passage therethrough of the eluted water dispersible substance.

22. Apparatus according to claim 21 wherein the inner container is provided a plurality of perforations on a side wall thereof.

23. Apparatus according to any one of claims 1 to 8 wherein the inner container is in the form of a bag.

24. Apparatus according to any one of the preceding claims wherein the inner container has means for closing the container when the container is not is use or is in transit.

25. Apparatus according to claim 24 wherein the means for closing the container is a lid.

26. Apparatus according to any one of the preceding claims wherein the biopolymer is one in which at least 50% (e.g. at least 60%, or at least 70%, or at least 80%, or at least 90%, or at least 95%, or at least 99%, for example

100%) of monomer units in the biopolymer are derived from renewable organic non-petroleum and non-coal source materials.

27. Apparatus according to any one of the preceding claims wherein the organic source material is an organic source that can be grown or cropped at intervals of one day or less, or one week or less, or one month or less, or three months or less, or six months or less, or on an annual, biennial or triennial basis, or at intervals of up to ten years or up to twenty years, or up to thirty years or up to forty years or up to fifty years.

28. Apparatus according to claim 27 wherein the organic source material is derived from an organic source that can be cropped on an annual or part annual basis.

29. Apparatus to any one of the preceding claims wherein the organic source material is selected from plant crops such as cereals, grasses, maize, potatoes, sugar beet and sugar.

30. Apparatus according to any one of the preceding claims wherein the biopolymer is polylactide (PLA) or a copolymer thereof.

31. Apparatus according to claim 30 wherein the biopolymer is polylactide homopolymer.

32. Apparatus according to any one of the preceding claims in kit form.

33. Apparatus according to any one of claims 1 to 31 in assembled form.

34. A product containing a mailing container within which is disposed an apparatus in kit form or assembled form as defined in claim 32 or claim 33.

35. A mailing container within which is disposed an inner container containing a plurality of dosage units as defined in any one of claims 1 to 31.

36. A method for preparing an aqueous solution of a water dispersible substance, which method comprises passing water through an apparatus as defined in anyone of claims 1 to 33 so as to swell or dissolve the encapsulating polymer and elute the water dispersible substance.