NZ286994A

NZ286994A - Use of hydrogel material in or as a plant growing medium, as a cold brick for packaging and medical dressings, in air freshner compositions and for plant transportation support

Info

Publication number: NZ286994A
Application number: NZ286994A
Authority: NZ
Inventors: George Wilfred Tucker
Original assignee: George Wilfred Tucker
Priority date: 1995-07-12
Filing date: 1996-07-12
Publication date: 1997-01-29
Also published as: GB9614492D0; GB2303125B; GB2303125A; GB9514240D0

Description

<div class="application article clearfix" id="description"> New Zealand Paient Spedficaiion for Paient Number £86994 Prlority Date(s): Oor-.p«of« Specification Filed: | - &> F iibii cation Dato:.2»9-JAty~&97. P.O. Journal No: ^1^.13;. • «•••<»*••••••••••< '' 6w * *"* 4 1? - \ ^22JUL 1996 \ Patents Form No. 5 P21121/ES NEW ZEALAND PATENTS ACT 1953 COMPLETE SPECIFICATION HYDROGEL POLYMER PRODUCTS I, George Wilfred Tucker, a British citizen, c/o Step by Step (UK) Ltd, Unit 1, Mari House, Old Websters Ropery, Deptford, Sunderland SR4 6DD, England, United Kingdom, do hereby declare the invention for which we pray that a patent may be granted to^us, and the method by which it is performed, to be particularly described in and by the following statement: -1- (followed by page la) 28 6 9 9 4 - la - HYDROGEL POLYMER PRODUCTS This invention relates to products including hydrogel polymeric materials. The invention also relates to methods of use of hydrogel polymeric materials, particularly but not exclusively to methods of recycling surplus or waste materials such as off cuts from manufacture of absorbent fillings for diapers, sanitary napkins and other absorbent pads. A variety of polymers form hydrogels, that is they absorb large amounts of water or aqueous solutions. Examples of such polymers are disclosed in GB-A-2156370, GB-A-2083417, GB-A-2048292 and GB-A-0278601. Polymers which may be employed in accordance with this invention are referred to hereafter simply as "hydrogels". According to a first aspect of the present invention a horticultural medium including a particulate hydrogel having a dimension up to 25 microns. Preferred media have particles with a dimension less than 10 microns. The absence of a substantial proportion of particles having a dimension greater than 25 microns, preferably 10 microns is preferred as such large particles have been found to be prone to degradation in use. A medium in accordance with the present invention may be used alone or mixed with soil or other conventional compost or growing medium. Media in accordance with this aspect of the present invention may be hydrated with a solution containing one or more fertilizers, biocides, plant growth regulators or other horticultural or agricultural compounds. These compounds have been found to be released slowly from the hydrated polymer particles, allowing long term treatment following a single application. Media in accordance with this aspect of the invention may be used as an integral component of compost for potting or may be applied as a top dressing. Media in accordance with this aspect of the present (followed by page 2) 28 6 9 9 4 -2- invention may be dyed to produce a decorative effect or to indicate the nature or amount of a fertiliser or other composition added to the gel. A particulate hydrogel material for use in accordance with this invention is advantageously provided by use of off-cuts, surplus or waste absorbent fillings from diapers. The absorbent portions of diapers often comprise particulate hydrogel material admixed with wood pulp or other cellulosic or fibrous absorbent materials. The presence of wood pulp confers an unexpected advantage in that the resultant horticultural medium reduces any tendency for the medium and any soil into which it is mixed, to be washed out for example by heavy rain or frequent watering. The medium of this invention may be used for ground stabilisation, preventing or reducing erosion by the elements or by passage of humans or animals. The horticultural medium of the first aspect of this invention may serve as a part replacement for peat in a conventional peat based compost, for example a compost formulated for ericaceous or other plants which prefer an acidic soil. According to a second aspect of the present invention packaging for cold storage of articles comprises a hydrated particulate hydrogel enclosed in an impermeable container. The container may be a flexible polymeric film sachet. Freezing or chilling of the hydrogel within the container affords a convenient means of storage of perishable articles such as food, eg fish or horticultural products. The packaging may be arranged in thin layers interspersed with the products. Melting of the frozen hydrogel does not release water, reducing any hygiene problem associated with transportation of fish or similarly degradable products. In accordance with a third aspect of the present invention an air freshener comprises a container containing a particulate hydrogel polymer hydrated with an aqueous solution of an airborne fragrance or air freshening or deodorising compound. The container may comprise a permeable sachet or other envelope. Alternatively a receptacle having one or more 28 6 99 4 -3- apertures communication with the atmosphere may be employed. An air freshener in accordance with this aspect of the invention may find application in relation to a room heater, for example a domestic of office central heating system. The container may be placed adjacent a radiator or other source of heated air. Drying of the hydrogel in use releases the fragrance or air freshener, allowing dispersion over a long period. The hydrogel may be rehydrated with an aqueous solution of the fragrance or other compound for repeated use. According to a fourth aspect of the present invention a medical or veterinary dressing comprises a hydrated particulate hydrogel enclosed within an impermeable container. The container may be a flexible polymeric film sachet. Such an embodiment of the invention may be used as a cold compress. Use of a permeable container may facilitate application of liniment or other lipophilic medicament which has been previously absorbed into the hydrogel. Such a dressing may be used for example as a veterinary bandage for horses legs. According to a fifth aspect of the present invention a plant transportation support comprises a body of hydrated hydrogel disposed in a permeable wrapping for example of polymeric or textile material, dimensioned to facilitate wrapping around the base of a tree or other plant during transportation. The product serves to support the stem or trunk of the plant and also provides a source of moisture which can drain onto the roots during transportation and storage. According to a sixth aspect of the present invention a process for recycling hydrogel polymeric materials used for manufacture of diapers comprises use of such materials to manufacture a product according to any preceding aspect of this invention. The invention is further described by means of example but not in any limitative sense. A horticultural medium is prepared by adding a quantity of water to scrap polymeric hydrogel material left over from manufacture of diapers. This method may advantageously incorporate wood pulp or other fibrous matter. The quantity of </div>

Claims

286 994 -4- water is chosen to achieve maximum absorbency. Colouring, fertiliser and any other horticultural compounds are dissolved in the water prior to addition to the polymeric material. The mixture is then allowed to stand for 20 minutes to equilibrate prior to mixing with compost. In an alternative process a reduced amount of water is added to produce a partially saturated gel. This gel may be softer and may be more easily sieved. Water may be subsequently added as desired. A vibrating screen may be employed to separate differently sized particles of the material. The present invention allows re use of the absorbent components of a diaper or surplus or waste absorbent materials resultant from diaper manufacture. In this method a lower seam of a used diaper is released allowing the gel to be discharged. The discharged gel may be used in a product as disclosed above. A replacement pad containing dry hydrogel may be inserted into the diaper. Such a diaper, intended for repeated use may have a more substantial construction, for example with towelling panels or outer cover. In a preferred embodiment of the invention off-cuts from manufacture of absorbent fillings for diapers may be employed. These absorbent fillings can incorporate wood pulp or other cellulosic fibres. These do not require separation from the hydrogel prior to use in accordance with the invention. The presence of cellulosic material is beneficial and enhances the stability of the horticultural medium in use. The tendency of the horticultural medium to be washed out by heavy rain or by mechanical erosion is reduced. The horticultural medium may be used as a partial or complete replacement for peat. The waste material from diaper manufacture may also be used for packaging of thermally sensitive products such as fresh fish or horticultural produce. The hydrogel, optionally together with pulp or other cellulosic material may be provided in a hydrated state packaged in polymeric film containers. The packages may be frozen or chilled before use in transportation of fish or other thermally degradable products. -5- 28 6 99 4 What we if"

1. A horticultural medium including a particulate hydrogel having a dimension up to 25 microns.

2. A medium as claimed in claim 1, wherein the hydrogel has a dimension up to 10 microns.

3. A medium as claimed in claim 1 or 2, wherein the hydrogel is hydrated with a solution of one or more of: a fertiliser, a biocide, a plant growth regulator, or other horticultural or other agricultural compound.

4. A medium as claimed in any preceding claim, wherein the hydrogel is admixed with a cellulosic material.

5. A medium as claimed in claim 4, wherein the cellulosic material is wood pulp.

6. A medium as claimed in any preceding claim, wherein the hydrogel is derived from a surplus or waste product from diaper manufacture.

7. A soil composition, wherein a medium as claimed in any preceding claim is used as a partial or entire replacement for peat.

8. Packaging for cold storage of articles comprising a hydrated particulate hydrogel enclosed in an impermeable container.

9. Packaging as claimed in claim 8, wherein the container is a flexible polymeric film sachet.

10. An air freshener comprising a container containing a particulate hydrogel polymer hydrated with an aqueous 28 6 9 9 4 -6- solution of an airborne fragrance or air freshening or deodorising compound.

11. A medical or veterinary dressing comprising a hydrated particulate hydrogel enclosed within an impermeable container.

12. A dressing as claimed in claim 11, wherein the container is a flexible polymeric film sachet.

13. A plant transportation support comprising a body of hydrated hydrogel disposed in a permeable wrapping dimensioned to facilitate wrapping around the base of a tree or other plant during transportation.

14. A process for recycling hydrogel polymeric materials used for manufacture of diapers, comprising use of such materials to manufacture a product according to any preceding claim.

15. A horticultural medium substantially as hereinbefore described.

16. Packaging for cold storage of articles substantially as hereinbefore described.

17. An air freshener substantially as hereinbefore described.

18. A medical or veterinary dressing substantially as hereinbefore described.

19. A plant transportation support substantially as hereinbefore described. McCABE AND COMPANY By ^ ATTORNEYS FOR THE APPLICANT