WO2023088611A1

WO2023088611A1 - Biodegradable woven sheet for cultivation of plant seedlings

Info

Publication number: WO2023088611A1
Application number: PCT/EP2022/078123
Authority: WO
Inventors: Lucas Everhardus Maria Langezaal
Original assignee: Everhard Consulting B.V.
Priority date: 2021-11-16
Filing date: 2022-10-10
Publication date: 2023-05-25
Also published as: NL2029774B1

Abstract

The present invention relates to a fully biodegradable cup shaped woven sheet for cultivation of plant seedlings or plants comprised of woven natural fibres and a biopolymer coating. The present invention further relates to a method for providing a biodegradable cup shaped woven sheet and use thereof for cultivation of plant seedlings or plants.

Description

BIODEGRADABLE WOVEN SHEET FOR CULTIVATION OF PLANT SEEDLINGS

Description

The market for propagating young plants or plant seedlings continuously requires improvement of the substrate system in which young plants are cultivated. For example, the propagation or cultivation substrate is continuously adapted because the market (reduce carbon footprint), government (strict environmental and health legislation, reduction of chemicals) and consumers increasingly demand alternative substrates for example in view of the peat being used as substrate. Furthermore, increased use of robotics and advanced machines are also being used to reduce labour cost, with the downside that these machines place higher demands on the delicate growing substrate as well as higher quality standards for the plants.

To meet these increasing demands, the propagation pots and plugs are continuously improved. For example, glue is added to bond the culture substrate resulting in the glue plug, a plant pot consisting of paper is developed, in which the substrate is put in a paper sleeve. Sheets of rice straw and coconut fibre with a binder were made in which the sheet can be pushed into the tray and can serve as a basket that is filled with peat substrate. A nestable cone was developed that can be easily fitted into a plant tray, the cone comprised of a thin, warm wire of hot-melt binder that is twisted in various directions around a spindle to eventually create a non-woven basket. The wires overlap each other and at the overlap fusing occurs so that a bond is formed. This basket is eventually filled with peat substrate. In the present developed products for plant plugs or plant cultivation containers, a binder, often a non-de gradable or synthetic binder, is used to bind the raw materials together. However due to the increasing and more strict government requirements there is a need to use improved and more environmentally friendly binders. Furthermore, due to the materials and binders used, the plant containers are less flexible, less durable, and prone to machine processing resulting in product losses.

Considering the above, there is a need in the art for improved and environmentally friendly plant cultivation container wherein binders are eliminated without sacrificing any other requirements of the plant plug or plant cultivation container. Such a product should preferably have an open structure to support for root growth but should be able to hold and contain the growth substrate for cultivation of plant seedlings. The product should also have a certain firmness in connection with the mechanical handling due to the increased use of machines and robots. The product should preferably be comprised of materials that are fully biodegradable that further provide sufficient cohesion and structure to the product, without the use of chemical binders.

It is an object of the present invention, amongst other objects, to address the above need in the art. The object of present invention, amongst other objects, is met by the present invention as outlined in the appended claims.

Specifically, the above object, amongst other objects, is met, according to a first aspect, by the present invention by a biodegradable cup shaped woven sheet for cultivation of plant seedlings or plants, wherein the sheet is comprised of woven natural fibres, wherein the sheet has a density of 50 to 350 g of fibres /m2, preferably 65 to 250 g of fibres /m2, more preferably 75 to 200 g of fibres /m2, most preferably 90 to 140 g of fibres /m2, and wherein at least one side of the sheet is comprised of a coating of biodegradable polymer for providing increased stiffness to the cup shaped woven sheet, wherein the sheet comprises between 5 to 40 wt%, preferably 10 to 30 wt%, more preferably 15 to 25 wt% biodegradable polymer, based on the total weight of the sheet, wherein said biodegradable polymer is one or more biodegradable polymers selected from the group consisting of colophony, starch-based biopolymers, agar, and bone meal-based biopolymers, preferably colophony. The biodegradable cup shaped woven sheet for cultivation of plant seedlings or plants of present invention can be fdled and hold plant growing substrate. The sheet comprises an open structure due to the woven fibre material providing an optimal structure root growth and development of the plant. The biodegradable cup shaped woven sheet is provided with a coating on at least one surface with a biodegradable polymer for providing increased stiffness and firmness to the cup shaped sheet in connection with the increased mechanical handling as indicated above. Finally the product is comprised of natural and biodegradable materials. The base fibres as well as the coating polymer is of natural origin (animal or plant based) and therefore complies with afore mentioned environmental legislation and fully biodegradable.

The sheet comprised of woven natural fibres can be obtained by weaving threads into a thin open weave. This sheet can be cut into a patch that is exactly the size of the inner surface of a plant tray, wherein the sheet can be pushed into the inner perimeter of a tray cub. The sheet fits into the tray as a basket or net that can be filled with plant growth substrate.

According to a preferred embodiment, the present invention relates to the biodegradable cup shaped woven sheet, wherein the biodegradable polymer coating is at least provided on the inner surface of the biodegradable cup shaped woven sheet. The sheet of natural fibres is reinforced for stiffness using a biodegradable polymer. In this case the bond is still made by the fabric but the stiffness comes from an added product. Smaller amounts of stiffer fibres can be added to the woven fibres or a biodegradable polymer such as starch is provided onto one side of the sheet of natural fibre. Preferably the biodegradable coating is provided on the inner side/surface of the biodegradable cup shaped woven sheet. Because the polymer is present on the inside/inner surface of the sheet and this sheet is positioned or pushed into the tray, the polymer coating does not come into contact with the plant tray inner surface which in turn may prevent that the woven sheet become more attached to the plant tray due to the biodegradable coating when on the outside surface of the woven sheet (i.e. the sheet will stick to the inside wall of the plant tray). In case the biopolymer coating is on the outside of the woven sheet, a release agent or additional water is needed to loosen the sheet comprising the plant seedling from the plant tray. Therefore, in case only the inner surface of the biodegradable cup shaped woven sheet is comprised of the biodegradable coating, the above issue when removing the plant seedling (including cup shaped woven sheet) from the plant tray is avoided. The biodegradable polymer coating is 100% natural origin, fully biodegradable and chemically stable and does not react with the natural fibre.

According to a preferred embodiment, the present invention relates to the biodegradable cup shaped woven sheet, wherein the natural fibres are of plant- or animal origin and one or more selected from the group consisting of jute, coconut, bamboo, viscose, cotton, cellulose, sisal, flax, hemp, wood, hoofed animal hair, animal hair, intestines, preferably jute, coconut or cotton. The stiffness of the fibre and the density of the weave determines the strength of the sheet. For example jute is a stiff fibre in contrast to viscose. If the tray type, cultivation and handling requires higher demands on firmness, a higher weight of the fabric can be used, whereby the mesh size becomes smaller and/or the fibre thickness increases. The firmness of the sheet of woven fibres of present invention can be adjusted by using thicker or thinner fibre and varying the mesh size, within the claimed ranges. However when outside these ranges, adverse affects on plant growth and plant /root development is observed. For example decreasing the mesh size too much will have negative effects on the growth of the roots and the bio-degradation rate of the natural fibre.

According to another preferred embodiment, the present invention relates to the biodegradable cup shaped woven sheet, wherein the sheet comprises a mesh size of between 2 to 8 mm, preferably 3 to 7 mm, more preferably 4 to 6 mm. The mesh size should be large enough to support proper plant root development and at the same time should provide sufficient base for holding the growth substrate and plant seedlings in the cup shaped sheet. Below 2 mm would affect the root development, and above 9 mm would result in a loss in structure and firmness of the cup shaped sheet and a loss of growth substrate going through the mesh of the woven sheet.

According to yet another preferred embodiment, the present invention relates to the biodegradable cup shaped woven sheet, wherein the sheet is fully biodegradable.

According to a preferred embodiment, the present invention relates to the biodegradable cup shaped woven sheet, wherein the coating of biodegradable polymer is water miscible. During harvesting of the grown plant from the plant tray, upon being removed from the tray, the roots or plants itself are often being damaged. Furthermore, the adhesive material that is being used to form the plant plug will also make contact to the (plastic) walls of the tray and is often also glued to the wall of the tray. The sheet of present invention used within such a plant tray prevents such difficulties and damages since the biodegradable polymer coating is preferably at the inside of the woven sheet and not in contact with the inside wall of the plant tray, and the biodegradable coating is water miscible, thereby when watering the plant seedling, the plant can be easily released from the tray without damaging the roots of the plant or risk of decomposing of the plant plug during release from the tray. The biopolymer coating is preferably at least provided on the inner surface of the biodegradable cup shaped woven sheet.

According to another preferred embodiment, the present invention relates to the biodegradable cup shaped woven sheet, wherein the biodegradable polymer is a mixture of at least 80 wt% colophony and at most 20 wt% vegetable-based wax based on the weight of the biodegradable polymer. Mixing the colophony with the vegetable-based wax results in lowering of the melting point and an improved water miscibility of the colophony. Colophony is a resin that is produced by conifers and pine trees with high adhesive strength. At room temperature colophony is very brittle and has a melting point of around 80 - 90 ° Celsius. We have found that when combined with a saturated fatty acid (for example stearic acid), that has bi-functional properties with a polar and a non-polar part, such a mixture becomes increased water miscible. Above 20 wt% of vegetable-based wax, although beneficiary for the water miscibility, the melting point of the coating becomes too low such that the composition becomes too flexible and adversely affects the stiffening properties of the biopolymer coating of the cup shaped sheet. A further surprisingly effect is that the biodegradation of the cup shaped woven sheet is even further improved. The biodegradation is greatly shortened compared to the degradation time of 100% colophony. This is important for the bioaccumulation of the polymer in the soil if several crops take place on the same plot within a year. By means of the ratio of this mixture, we are able to control the degradation rate of the system depending on the cultivation used.

According to a preferred embodiment, the present invention relates to the biodegradable cup shaped woven sheet, wherein the vegetable based wax is selected from the group consisting of soy wax, palm wax, preferably soy wax. The saturated fatty acids are added to the colophony in the form of vegetable wax, preferably soy wax. Soy wax is made from hydrogenated soybean oil and is a 100% renewable product, produced from fast-growing crops and does not comprise further toxic chemicals or by products.

According to yet another preferred embodiment, the present invention relates to the biodegradable cup shaped woven sheet, wherein the natural fibres are approximately 0.5 to 1.5 mm thick, preferably 0.8 to 1.2 mm thick

The present invention, according to a second aspect, relates to a method for providing a biodegradable cup shaped woven sheet as described above into a plant tray or plant cup, wherein at least one side of the biodegradable woven sheet is being coated with a biodegradable polymer providing a coated biodegradable woven sheet for providing increased stiffness to the cup shaped woven sheet, wherein the sheet comprises between 5 to 40 wt% biodegradable polymer, based on the total weight of the sheet, wherein said biodegradable polymer is one or more biodegradable polymers selected from the group consisting of colophony, starch-based biopolymers, and bone meal -based biopolymers, preferably colophony.

According to a preferred embodiment, the present invention relates to the method wherein the biodegradable polymer is provided as a hotmelt sprayed under pressure on one surface of the biodegradable woven sheet, preferably the biodegradable polymer coating is provided on the inner surface of the biodegradable woven sheet when said biodegradable woven sheet is provided in a plant tray for cultivation of plants.

According to another preferred embodiment, the present invention relates to the method wherein the coated biodegradable woven sheet is heated at 30 to 80 °C, preferably 40 to 60 °C, for example by means of infrared or warm air, for at most 10 seconds, preferably at most 5 seconds, directly followed by cutting the coated biodegradable cup shaped woven sheet into a size corresponding with the dimensions of said plant tray for substantially covering the inside surface of the plant tray and providing the coated biodegradable cup shaped woven sheet into a plant tray or plant cup, thereby providing the biodegradable cup shaped woven sheet having the shape of said plant tray of plant cup.

The present invention, according to a further aspect, relates to the use of a biodegradable cup shaped woven sheet for cultivation of plant seedlings or plants. Preferably the biodegradable cup shaped woven sheet is provided in a plant tray for cultivation of plants and the sheet corresponds with the dimensions of said plant tray covering the inside surface of the plant tray. The woven sheet of fibers covers the bottom and inner circumference of the plant tray cube. The woven sheet is like a net, that is open at the top and that can be fdled with a growth substrate mixture for plant cultivation. The firmness of the sheet material and the counter pressure of the tray wall ensure that the net remains in position and is not pressed by the fdling pressure of the substrate filling machine.

The present invention will be further detailed in the following examples and figures wherein:

Figure 1: Left upper picture (A) shows a biodegradable woven sheet of woven natural fibers, more specifically jute, that has not been coated with a biopolymer according to present invention. The right upper picture (B) shows this woven sheet after being applied into a plant tray or cup, to provide a cup shape, but loses the shape quickly after removal from the cup. The lower left picture (C) shows the biodegradable woven sheet of woven natural fibers, more specifically jute, that has been coated with a biopolymer, more specifically rosin (colophony), according to present invention, after being applied into a plant tray or cup, to provide a cup shape, and retaining this cup shape after removal from the cup or tray.

Figure 2: The upper picture (A) shows plant trays being filled with the biodegradable woven sheet of woven natural fibers coated with a biopolymer according to present invention. After applying the cup shaped sheet, the plant trays are being filled with growth substrate and plant seedlings for cultivation and plant growth. The lower left picture (B) shows the cup shaped biodegradable woven sheet of woven natural fibers coated with a biopolymer according to present invention that has been filled with growth substrate and has been removed from a plant tray or cup using a wooden pin to simulate the mechanical removal of the biodegradable cup shaped woven sheet for cultivation of plants according to present invention. The cup shaped structure remains fully intact and in cup shape after removal. On the lower right picture (C) a biodegradable woven sheet of identical biodegradable fibre material and filled with growth substrate as in picture 2B, however not being coated with colophony. After mechanical removal by a wooden pin, the cup shaped structure is less stable or even lost, and the growth substrate including biodegradable woven sheet falls out of shape and apart after removal from the plant tray.

Figure 3: Shows a plant seedling that has been cultivated using the biodegradable woven sheet of woven natural fibers coated with a biopolymer according to present invention. The growth substrate remains intact after being removed from the plant trays. Plant root development is unaffected by the biodegradable woven sheet of present invention. Furthermore, first signs of biodegradation are visible in the upper regions of the biodegradable woven sheet of present invention; green spots appear of fungal growth on the outside of the sheet, indicating the degradation of the colophony coating on the outside of the woven sheet of present invention.

Examples

Example 1 - Production of the biodegradable cup shaped woven sheet and use thereof in plant trays

A fabric jute sheet is provided comprised of woven jute fibres (about 120 g/m2) having a mesh size of about 5 mm. The fabric sheet is sprayed on one side with a warm hot melt comprising colophony (rosin), to provide the sheet with a coating of biodegradable polymer 20 wt% based on the total weight of the sheet. This produces a fluffy thin layer on the fabric only. The hotmelt is sprayed under pressure on one side of the fabric (preferably being the inside surface of the cup shaped woven sheet), wherein the biodegradable polymer is cooled down the moment the mist comes into contact with the fabric providing a hot melt layer on the fabric.

The coated woven fabric sheet is now cut to size using a cutting machine to create a ribbon of tailor-made patches that match the inner dimensions of the plant tray or plant cup. This ribbon of coated patches is rolled out over the plant tray such that each of the plant tray apertures are covered with a patch of coated woven fabric sheet. The ribbon of patches is then heated by means of infrared or warm air for a short time (i.e. a few seconds depending on the supply temperature). The pieces are then separated from each other by means of a knife and pushed directly into the tray by a pusher having the same shape as the plant tray aperture. The coated fabric now takes the shape of the tray and due to the rapid cooling it stiffens into a sturdy cup shape “basket”, wherein the coating provides the increased stiffness to the cup shaped woven sheet. Heating , cutting and pushing is achieved within 10 to 12 seconds, preferably in 5 to 8 seconds. If the plant tray is fdled with the.biodegradable cup shaped woven sheets of present invention, they can be filled with growth substrate for plant seedlings.

Claims

8 Claims

1. A biodegradable cup shaped woven sheet for cultivation of plant seedlings or plants, wherein the sheet is comprised of woven natural fibres, wherein the sheet has a density of 50 to 350 g of fibres /m2, and wherein at least one side of the sheet is comprised of a coating of biodegradable polymer for providing increased stiffness to the cup shaped woven sheet, wherein the sheet comprises between 5 to 40 wt% biodegradable polymer, based on the total weight of the sheet, wherein said biodegradable polymer is one or more biodegradable polymers selected from the group consisting of colophony, starch-based biopolymers, agar, and bone meal-based biopolymers, preferably colophony.

2. Biodegradable cup shaped woven sheet according to claim 1, wherein the natural fibres are of plant- or animal origin and one or more selected from the group consisting of jute, coconut, bamboo, viscose, cotton, cellulose, sisal, flax, hemp, wood, hoofed animal hair, animal hair, intestines, preferably jute, coconut or cotton.

3. Biodegradable cup shaped woven sheet according to claim 1 or 2, wherein the biodegradable polymer coating is at least provided on the inner surface of the biodegradable cup shaped woven sheet.

4. Biodegradable cup shaped woven sheet according to any one of the claims 1 to 3, wherein the sheet comprises a mesh size of between 2 to 8 mm, preferably 3 to 7 mm, more preferably 4 to 6 mm.

5. Biodegradable cup shaped woven sheet according to any one of the claims 1 to 4, wherein the container is fully biodegradable.

6. Biodegradable cup shaped woven sheet according to any one of the claims 1 to 5, wherein the coating of biodegradable polymer is water miscible.

7. Biodegradable cup shaped woven sheet according to any one of the claims 1 to 6, wherein the biodegradable polymer is a mixture of at least 80 wt% colophony and at most 20 wt% vegetablebased wax based on the weight of the biodegradable polymer.

8. Biodegradable cup shaped woven sheet according to claim 7, wherein the vegetable-based wax is selected from the group consisting of soy wax, palm wax, preferably soy wax. 9

9. Biodegradable cup shaped woven sheet according to any one of the claims 1 to 8, wherein the natural fibres are approximately 0.5 to 1.5 mm thick, preferably 0.8 to 1.2 mm thick

10. Method for providing a biodegradable cup shaped woven sheet according to any one of the claims 1 to 9 into a plant tray or plant cup, wherein at least one side of the biodegradable woven sheet is being coated with a biodegradable polymer providing a coated biodegradable woven sheet for providing increased stiffness to the cup shaped woven sheet, wherein the sheet comprises between 5 to 40 wt% biodegradable polymer, based on the total weight of the sheet, wherein said biodegradable polymer is one or more biodegradable polymers selected from the group consisting of colophony, starch-based biopolymers, and bone meal-based biopolymers, preferably colophony.

11. Method according to claim 10, wherein the biodegradable polymer is provided as a hotmelt sprayed under pressure on one surface of the biodegradable woven sheet, preferably the biodegradable polymer coating is provided on the inner surface of the biodegradable woven sheet when said biodegradable woven sheet is provided in a plant tray for cultivation of plants.

12. Method according to claim 10 or 11, wherein the coated biodegradable woven sheet is heated at 30 to 80 °C, for example by means of infrared or warm air, for at most 10 seconds, directly followed by cutting the coated biodegradable cup shaped woven sheet into a size corresponding with the dimensions of said plant tray for substantially covering the inside surface of the plant tray and providing the coated biodegradable cup shaped woven sheet into a plant tray or plant cup, thereby providing the biodegradable cup shaped woven sheet having the shape of said plant tray of plant cup.

13. Use of a biodegradable cup shaped woven sheet according to any one of the claims 1 to 9 for cultivation of plant seedlings or plants.

14. Use according to claim 13, wherein the biodegradable cup shaped woven sheet is provided in a plant tray for cultivation of plants and the sheet corresponds with the dimensions of said plant tray substantially covering the inside surface of the plant tray.