WO2007020250A1

WO2007020250A1 - Plant pots, plant and tree guards, and plant and tree wrap

Info

Publication number: WO2007020250A1
Application number: PCT/EP2006/065275
Authority: WO
Inventors: Peter Kelly; Aidan Lynch
Original assignee: Uzet Patents Limited
Priority date: 2005-08-12
Filing date: 2006-08-11
Publication date: 2007-02-22
Also published as: IES20050530A2

Abstract

A horticultural product, such as a plant pot, seed tray or plant guard, comprises a fibrous layer and at least one biodegradable polymer layer.

Description

Plant Pots, Plant and Tree Guards, and Plant and Tree Wrap

FIELD OF THE INVENTION

The present invention relates to the design and construction film and sheet products for horticultural applications more specifically tree guards and plant pots that have an acceptable service life during use but readily biodegrade in the soil with no adverse effect on plant growth.

An extension of the invention further relates to the incorporation of additive materials that enhance the protection of the plant from fungal, insect and animal attack.

BACKGROUND OF THE INVENTION

The use of thermoplastic materials to produce tree guards, plant pots and trays are well know and commercially available. Unfortunately these products are manufactured using conventional thermoplastic materials such as polypropylene, polystyrene and polyethylene which are not degradable. The product either has to be collected after its usable life for subsequent disposal by landfill or incineration with additional cost impact for the end user.

In the use of plant pots and seed trays, when the time for the plant to be repotted into the soil the pot or tray has to be removed potentially causing damage to the fragile plant use and then subsequently disposed. Because of the high level of soil contamination, potential for fungal contamination etc the plant pot or tray cannot be reused or recycled without a major cleaning process which is often more costly than the original value of the container. Further in Europe these trays and pots are now considered to be a form of packaging for the plants and susceptible to a packaging tax. There is a definite need for a container that can be placed directly into the ground and will degrade rapidly in the soil allowing the root structure of the plant to develop without inhibition.

Tree guards are much more difficult to manage since they are often used in more remote areas to help the stabilization of small plants against animal and insect attack. These are typically made of heavy durable plastic sheet, mesh, netting or non- woven blankets and held in position with stakes or the like. As the plant or tree grows then the tree guard may provide a restriction on the rate of growth unless it is removed. Hence there is a problem in managing the protection of the tree or plant and allowing maximum growth potential. In the more remove areas where the tree guards are not managed then damage from external sources eg wind, physical abuse etc can occur and the resulting broken tree guard becomes litter which is both damaging on the environment and to animals. There is a need for a tree guard which provides protection for the tree or plant during the early growth cycle but then subsequently degrades naturally with no adverse effect on the environment. The production of biodegradable trays is known and typically consisting of combining water soluble polymers with other additives to form a pulp and molding the paste to form a tray.

US patent specification 6,878,199 discloses a biodegradable container produced through the use of pregelled starch suspension. Whilst this has some very limited resistance to moisture it does not have the durability to container a seedling in a moist environment for several months during the early growth period without significant loss in mechanical strength.

US patent specification 6,490, 827 discloses a biodegradable tray comprising a suction molded dried and hot pressed tray from pulp and up to 25% biodegradable resin.

Chinese patent 1463581 describes a plant based composition for molding flower pots comprising 60-90 parts plant fiber, 1-12 parts a binder selected from starch, wheat flour, Chinese wax and/or dextrin, 1-20 parts additives, and 1-10 parts dried fermented manure.

Meanwhile, as a pulp mold having superior mechanical strength and good dimensional accuracy, there has been proposed a pulp mold produced by wet suction molding of pulp as a raw material, which comprises fine fibers having 150-500% of water retaining capacity defined in Japanese Patent Laid-open (Kokai) No. 10-311000/1998. Although use of this pulp mold is not particularly limited, it is to be mainly used as a packaging material, and use for tray for raising seedlings is not suggested.

Further, there has also been proposed a method for raising seedlings, wherein seedlings are raised in biodegradable cells placed in a conventionally used plastic tray (Japanese Patent Laid-open (Kokai) No. 10-225235/1998) and a product in which a thin film of non-biodegradable substance is formed on a surface of a biodegradable plastic article (Japanese Patent Laid-open (Kokai) No. 11-227110/1999). This process is very difficult to apply in a large volume production environment and does not have any commercial value.

Furthermore, there has also been proposed a plastic mold composed of a mixture of 95-60 mass % of biodegradable plastic and 5-40 mass % of coconut shell (Japanese Patent Laid- open (Kokai) No. 10-67876/1998) and a biodegradable material obtained by kneading 51- 70 mass % of biodegradable resin and 30-49 mass % of paper powder (Japanese Patent Laid-open (Kokai) No. 10-323810/1998). However this type of composition will be very difficult to mold in thin wall applications typically used in plant pot construction and hence the cost of molding and material will be prohibitive for the normal high volume markets being considered for these types of product.

There are many patents pertaining to the construction of tree guards but no mention of specific materials of construction.

US Patent specification 6,625,926 describes a tree and shrub stabilizing apparatus comprising a stake with multiple straps attached to the tree as a means to protect the tree from wind damage. This does not provide any protection from animals eating the young leaves.

The description of a tree guard comprising a flat sheet having interlocking wing shaped tabs which connect when the sheet is rolled into a cylinder is disclosed in US Patent specification 6,408,569.

US Patent specification 6,233,868 describes a conical shaped housing with tabs that act as anchoring stakes, whilst US patent specification 6,219,962 describes a tubular shape with locking fasteners and wire supports.

US patent application 5,809,609 describes a folded panel with reclosable zip-type fasteners where the fastener is connected to the panel by heat welding or adhesive bonding.

None of the disclosures make reference a composition for the tree guard or the use of biodegradable products to limit the environmental effect after the effective lifecycle for the tree guard has been completed. Further there is no mention of the use of additive materials that would act as repellants to animals and insects to provide additional protection for the plants.

Coated paper products have been extensively used in food packaging and for disposable cups for hot and cold drinks. Paper has been considered as an alternative mulch product to the more traditional polyethylene film but generally degrades too quickly, does not retain sufficient ground moisture or lacks sufficient strength to be used in commercial agricultural operations. Coating paper with various compounds such as polyethylene, polypropylene, or polyvinyl chloride, polyvinyldene chloride, styrene butadiene, carboxylated styrene butadiene, carboxylated acrylonitrile butadiene are well known.

US Patent specifications 3,810,328, 3,938,280 and 3,939,606 disclose paper-based mulches with coatings that include organic resin or plastic coatings such as polyethylene, polypropylene, polyvinyl chloride, wax-based coatings, polyvinyl acetate, Saran or similar coatings. These are generally not acceptable because they do not biodegrade and provide a more difficult disposal problem to conventional polyethylene mulch films.

US Patent specifications 4,782,626, 5,163,247, 5,672,434 and 5,866,269, disclose paper or cellulose fiber mulches with latex coatings or related methods whilst US Patent specifications 5,532,298 and 5,853,541 provide descriptions of agricultural mulches made by combining mixtures of linters, pulps and water holdout materials or pulps, polyethylene fibers and, optionally, water holdout materials.

US Patent specification 5,096,941 discloses a degradable composition comprised of polyethylene and cerium stearate which can be made into a film and used as agricultural mulch. The degradation process is predominantly due to oxidative and UV breakdown of the polyethylene rather than microbial attack; this process is very difficult to control when a specific life cycle requirement is needed. US Patent specification 5,934,011 discloses a seed mat comprised of a water soluble paper layer, water absorbing polymer film layer and seeds. This product may be adequate for very early incubation of seeds but provides not mechanical support to seedling or plants.

US Patent specification 6,033,747 discloses the use of various biodegradable polyesters comprised of poly (3-hydroxybuturate-co-3-hydroxyhexanoate) to laminate base materials to form agricultural mulches and US Patent specification 6,040,063 additionally discloses biodegradable hydroxyl functionalized polyester compounds and mulches made there from this polymer. US patent specification 6,625,923 further discloses paper coated with polymerized vegetable oils for use as biodegradable mulch.

Whilst a variety of products have been developed none possess the qualities required for the horticultural products of this in invention. There is a need for the products of this invention to provide a function comparable to existing non degradable products during the service life and then biodegrade with no residual toxicological effect to the soil.

SUMMARY OF THE INVENTION

The present invention is formed biodegradable products that can function as a plant pot, seed tray, seed guard, plant guard or tree guard that has sufficient mechanical strength for commercial operation and sufficient longevity for it to meet the required in field performance requirements before degrading with no toxic impact on the neighboring soil or vegetation. Other advantages include the ability to control the strength of the fabricated product, enhance the growing potential of the seed, plant, shrub or tree and rate of biodegradation of the fabricated product.

The preferred embodiments, when used in a horticultural application, will eventually degrade to primarily water, carbon dioxide and biomass.

In accordance with one preferred embodiment of the invention the fabricated product is formed from a coated product comprising a paper or fibrous layer and at least one biodegradable polymer layer where the biodegradable polymer layer provides a partial water barrier to help retain initial strength of the coated paper during service; the fabricated product being used to product a plant pot, seed tray, seed guard, plant guard or tree guard.

In accordance with another preferred embodiment of the invention the fabricated product is formed from a coated product comprising a paper or fibrous layer and at least one biodegradable polymer layer coated on each side of the paper; the fabricated product being used to product a plant pot, seed tray, seed guard, plant guard or tree guard.

In accordance with another preferred embodiment of the invention the fabricated product is formed into a cup comprising a side component and a base component where the side and base of the cup are sealed together using the biodegradable coating or an adhesive layer; the fabricated product being used to produce a plant pot, seed tray, seed guard, plant guard or tree guard,

In accordance with another preferred embodiment of the invention the fabricated product is formed into a cylindrical or rectangular tube from a sheet of material where the edge is sealed with mechanical fasteners, clips, adhesive of heat sealed using the biodegradable coating as the bonding layer; the fabricated product being used to produce seed guard, plant guard or tree guard.

In accordance with another preferred embodiment of the invention the fabricated product further contains additives that provide nutriment value to the seed, plant, shrub or tree contained within the fabricated product; the fabricated product being used to product a plant pot, seed tray, seed guard, plant guard or tree guard.

In accordance with another preferred embodiment of the invention the fabricated product further contains additives that provide the ability to repel insects and animals that may have a detrimental effect on the seed, plant, shrub or tree contained within the fabricated product; the fabricated product being used to product a plant pot, seed tray, seed guard, plant guard or tree guard.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

The present invention relates to the design and construction paper products for horticultural applications more specifically tree guards and plant pots that have an acceptable service life during use but readily biodegrade in the soil with no adverse effect on plant growth.

In one preferred embodiment of the invention a cup is formed which can be used as a plant pot using a conventional cup making machine. The cup comprises two pieces of paper, a side piece and a base piece of paper, which are brought together in a continuous operation either as roll or sheet fed stock. The shapes are punched out in a continuous manner and fed into a cup forming station where they are formed and crimped into position. During this operation either a heat or a secondary adhesive is applied to specific areas of the paper to form the side seam and base seams. A curled edge is formed on the upper portion of the cup lip to provided additional stiffness to the construction. Many cup making machinery suppliers are know, however one type of cup making machine particularly suitable for making plant pot grade paper cups are those supplied by Paper Machinery Corporation, Milwaukee, WI. More detailed description of several types of cup making machine can be found in US patent specifications 5,752,907 and 5, 435,804. Drainage holes are preferably formed in the base of the cup to provide drainage during the plant growing operations. These drainage holes may be formed in the base of the cup during the component cutting operation in the cup making process or as a latter operation.

The geometry of the cup/plant pot is such that the diameter of the open portion is larger than the diameter of the base. Typically the diameter of the base is from about 50% to about 98% the diameter of the open portion of the plant pot to provide better stability. The open portion of the plant pot should preferably have a diameter of at least about 50mm and not more than about 400mm. The preferably height of the plant pot should be at least about 25mm and not more than about 200mm.

A variety of paper grades including mutiwall, super calendared kraft, extensible kraft, unbleached kraft, bleached grade paper or any paper material providing the appropriate attributes are used. The paper layer may also contain suitable wet strength additives and /or synthetic or natural fibers. More preferably the paper may also contain a portion recycled paper pulp obtained for a variety of industrial and post consumer sources. It is preferred that the base weight of the paper should be in the range of about 100 gsm (gram per square meter) and about 450gsm_; more preferably from about 180 gsm to about 400gsm and most preferably from about 250 gsm and about 360 gsm.

In one embodiment of the plant pot invention the paper is surface treated during the paper forming process to a barrier layer impervious to liquid water but not affecting the ultimate biodegradability of the paper.

In another embodiment of the plant pot invention the paper is coated with a polymeric biodegradable coating to enhance the resistance and durability of the paper to water during the growing period of the plant. Preferably the biodegradable coating is applied to the external surfaces of the plant pot to protect the paper from watering, rain and erosion from the elements. In the most preferred embodiment of the invention the biodegradable coating is applied to both surfaces of the paper, the mass of the coating on each side of the paper may vary from about 10% to about 90%, more preferably 25% to about 75% and most preferably from about 40% to about 60% of the total amount of polymer coated onto the paper.

The polymeric coating is applied to the paper in the form of a continuous or discontinuous film having a weight from about 5gsm to about lOOgsm per coat application. More preferably the coating thickness of the polymeric coating should be from about 10 gsm to about 50 gsm on either side of the paper. Preferably the polymeric coating should be less than 60% the total mass of the total mass of the paper plus the coating, more preferably less than 40% of the total mass and most preferably less than 20% the total mass of the paper plus the coating.

In another preferred embodiment of the invention a tree or plant guard is formed from a sheet of paper with a polymeric coating applied to both sides of the paper by forming a cone shaped device with a bonded side seam where the diameter of the lower end section is from about 40% to about 99% the diameter of the upper end section and more preferably where the diameter of the lower end section is from about 60% to about 90% and most preferably where the diameter of the lower end is from about 65% to about 85% the diameter of the upper end section and more preferably where the diameter of the lower end section diameter. The diameter of the smaller section is preferably from about 50mm to about 300mm. In another preferred embodiment of the invention a tree or plant guard is formed from a sheet of coated paper with a polymeric coating applied to both sides of the paper by forming a tube shaped device with a bonded side seam where the diameter is preferably from about 50mm to about 300mm.

In another embodiment of the invention the tree or plant guard the external coating of the fabricated product may constructed from any type of degradable coatings such as oxo- degradable or biodegradable whilst the inner coating is constructed from a biodegradable polymeric composition.

In another embodiment of the invention the plant or tree guard is a rectangular shape by taking a flat sheet of coated paper and applying crimping lines along the length of the paper sheet as shown in Figure 1 to provide five sections, this facilitates easy folding the paper. The dimensions AB and CD are identical as are dimensions BC and DE. Dimensions AB and BC may be the same or different. Dimension EF is smaller than AB with EF being from about 25% to about 99%, more preferably about 35% to about 85% and most preferably from about 40% to 70% the dimension of AB. For use, the tree guard is folded in to a rectangular shape and held together by fastener device holding section AB to section EF. The fastener device may be a mechanical clip or pin constructed from a biodegradable plastic or an adhesive device. The adhesive device is preferably a pressure sensitive tape which has been applied to the vertical portion of EF and protected with a barrier layer, the barrier layer being removed just prior to assembly of the tree guard. In another embodiment of the invention a liquid adhesive is applied during final construction of the tree guard where the adhesive is preferably a hot melt adhesive, moisture curing polyurethane adhesive or solvent based adhesive with high wet strength characteristics.

For tree guard devices the preferred base weight of the paper is from about 250 gsm to about 700 gsm, more preferable from about 280 gsm to about 600 gsm and most preferably from about 300 gsm to about 500 gsm.

In another embodiment of the plant and tree guard invention the paper is coated with a polymeric biodegradable coating to enhance the resistance and durability of the paper to water during the growing period of the plant. Preferably the biodegradable coating is applied to the external surfaces of the plant pot to protect the paper from watering, rain and erosion from the elements. In the most preferred embodiment of the invention the biodegradable coating is applied to both surfaces of the paper, the mass of the coating on each side of the paper may vary from about 10% to about 90%, more preferably 25% to about 75% and most preferably from about 40% to about 60% of the total amount of polymer coated onto the paper. The polymeric coating is applied to the paper in the form of a continuous or discontinuous film having a weight from about 5gsm to about lOOgsm per coat application. More preferably the coating thickness of the polymeric coating should be from about 10 gsm to about 50 gsm on either side of the paper. Preferably the polymeric coating should be less than 60% the total mass of the total mass of the paper plus the coating, more preferably less than 40% of the total mass and most preferably less than 20% the total mass of the paper plus the coating.

The articles can be formed from a variety of paper grades including mutiwall, fluted, corrugated, super calendared kraft, extensible kraft, unbleached kraft, bleached grade paper or any paper material providing the appropriate attributes are used. The paper layer may also contain suitable wet strength additives and /or synthetic or natural fibers. More preferably the paper may also contain a portion recycled paper pulp obtained for a variety of industrial and post consumer sources. The paper may also be constructed having a layer of the paper constructed from bleached pulp and a portion of the paper from unbleached pulp.

The polymeric composition used to coat the paper may be applied either to one side or to both sides of the paper and further may be applied as a single coating or multiple coatings to either side of the paper. More preferably the coating is applied to the inside of the pot construction to provide additional protection against moisture in the soil during the plant growing process. Most preferably a coating is applied to both the inner and outer surfaces of the sidewalls of the pot.

The polymeric coating is applied to the paper in the form of a continuous or discontinuous film having a weight from about 5gsm to about lOOgsm per coat application. More preferably the coating thickness of the polymeric coating should be from about 10 gsm to about 50 gsm on either side of the paper. Preferably the polymeric coating should be less than 75% the total mass of the total mass of the paper plus coating, more preferably less than 50% of the total mass and most preferably less than 25% the total mass.

The polymeric coating may be applied to the paper either as a 100% liquid system, a solution of the polymer in a carrier liquid or as dispersion in an aqueous medium. More preferably the polymeric coating is applied as a 100% liquid system or as an aqueous dispersion. Most preferably the coating is applied from a molten form.

The polymeric composition used to coat the paper or board should preferably be degradable where the degradation can take place over a period of several weeks to several years depending on the nature of the specific application and the required service life. The degradation may be via attack of microrganisms, hydrolysis, thermal oxidative degradation from solar sources, UV degradation for solar sources or a combination of several mechanisms. More preferably is that at least part the degradation process is through a biodegradation mechanism and most preferably that the polymeric coating will degrade according to ASTM D6400 or DIN 15700. Many different biodegradable polymers and blends may used to form the polymer coating. Whilst not being exclusive these can include polylactic acid, polyglycolic acid, polycaprolactone, polyalkylene carbonates, polyhydroxyalkanoates,tpolyvinyl alcohol, natural or chemically modified starches, soy proteins, tall oil and/or wood rosins, tall oil and/or wood esters, tall oil and/or wood rosin derivatives, urea formaldehyde resins, melamine formaldehyde resins, alkyd resins, polymerized vegetable oils, polyurethanes derived from soy and other vegetable based polyols, polyurethanes derived from castor oil based derivatives, synthetic aliphatic and aromatic copolyesters comprising monomers selected from 1, 4 butane diol, 1, 3 propane diol, ethylene glycol, adipic acid, succinic acid, succinic anhydride, terephthalic acid, lactic acid, colophony, natural rubber, gum arabic, cellulose acetate, cellulose butyrate, cellulose proprionate.

Degradable coatings may be selected from polyolefin homopolymer or copolymer compositions which do not contain any stabilizer packages or those containing prodegradant additives that enhance the rate of oxidative attack on the polymer backbone. Whilst not being exclusive preferable prodegradant are those that have no impact on soil toxicity and more preferably are based on ferric complexes and most preferable is ferric stearate.

A further embodiment of the invention is incorporating an insect or animal repellent on the surface of the fabricated product, in the paper or in the polymeric coating. A preferred embodiment is where the insect or animal repellant is compounded within the biodegradable polymer prior to coating onto the paper.

A further embodiment is where the additive also has fungicidal and bacterial properties to further enhance the growth of the plant.

A further embodiment of the invention is where the additive is neem seed oil, orange oil or citronella oil.

Claims

1. A horticultural product comprising a fibrous layer and at least one biodegradable polymer layer.

2. A horticultural product according to claim 1 comprising two biodegradable polymer layers, the fibrous layer residing between said two polymer layers.

3. A horticultural product according to any preceding claim wherein the fibrous layer is paper.

4. A horticultural product according to any preceding claim wherein the fibrous layer has an approximate base weight within any one of the following ranges : 100 gnrϊ² to 450 gm^"2 , 180 gnrϊ² and 400 gnϊ², 250 grrT² and 360 gm^"2, 250 gm^"2 and 700 gm^"2, 280 gm^"2 and 600 gm^"2, 300 gm^"2 and 500 gm^"2.

5. A horticultural product according to any preceding claim wherein an external polymer layer comprises an oxo-biodegradable composition.

6. A horticultural product according to any preceding claim comprising one, or combination, of the following additives: fungicide, bactericide, insect repellent, animal repellent.

7. A horticultural product according to claim 6 wherein the additive comprises any one, or combination, of the following: neem seed oil, orange oil, citronella oil.

8. A horticultural product according to any preceding claim wherein the at least one biodegradable polymer layer comprises either, or both, of the following: a polyolefin homopolymer, a copolymer.

9. A horticultural product according to any preceding claim wherein the at least one biodegradable polymer layer comprises a prodegradant.

10. A horticultural product according to claim 9 wherein the prodegradant comprises a ferric compound.

11. A horticultural product according to claim 10 wherein the ferric compound comprises ferric stearate.

12. A horticultural product according to any preceding claim wherein the at least one biodegradable polymer layer comprises any one, or combination of the following: poiylactic acid, polyglycolic acid, polycaprolactone, a polyakylene carbonate, a polyhydroxyalkanoate, polyvinyl alcohol, natural starch, chemically modified starch, soy protein, tall oil, wood rosin, wood ester, tall oil derivative, wood rosin derivative, urea formaldehyde resin, melamine formaldehyde resin, alkyd resin, polymerised vegetable oil, polyurethane derived from soy or other vegetable based polyol or derived from castor oil based derivatives, synthetic aliphatic copolyester, synthetic aromatic copolyester, colophony, natural rubber, gum Arabic, cellulose acetate, cellulose butyrate, cellulose propionate.

13. A horticultural product according to claim 12 wherein the at least one biodegradable polymer layer comprises either, or both, of a synthetic aliphatic copolyester or/and a synthetic aromatic copolyester wherein said copolyester comprises any one, or combination, of monomers selected from the following: 1 ,4, butane diol, 1 ,3 propane dioi, ethylene glycol, adipic acid, succinic acid, succinic anhydride, tetraphthalic acid, lactic acid.

14. A horticultural product according to any preceding claim wherein the at least one biodegradable polymer layer is degradable via any one, or combination, of the following mechanisms: microorganism attack, hydrolysis, thermal oxidation from solar sources, UV from solar sources.

15. A horticultural product according to any preceding claim wherein the at least one biodegradable polymer layer comprises less than any one of the following percentages of the total mass of the product: 75%, 50%, 25%.

16. A horticultural product according to any preceding claim wherein the fibrous layer comprises recycled paper.

17. A horticultural product according to any one of the preceding claims comprising any one, or combination, of the following: plant pot, seed tray, seed guard, plant guard, tree guard.