NL1022511C2 - Biodegradable soil coverage. - Google Patents

Description

1 1

Brief indication: Biodegradable soil cover.

The invention relates to a biodegradable soil cover formed by a fleece, which connects to the shape of the surface of the soil, comprising a biodegradable fiber connected to each other with an organic binder, and to a method for the preparation of such a soil cover, on a dry powdered mixture for the manufacture of such a soil cover and on a method for preparing a biodegradable soil cover suspension.

A biodegradable soil cover of the type mentioned in the preamble is known from WO 00/32030. The binder mentioned in this publication is latex. The soil cover is applied in the form of an aqueous suspension in which the fibers and the latex are incorporated. The drawback of this ground covering material 15 is the fact that bonding of the fibers is only obtained by drying the latex. In humid or wet weather it is thus not possible to apply such a ground cover.

US-A-6,029,395 further discloses a biodegradable bottom covering material which is formed by an open-cell foam material, which must first be foamed before placing the ready-made mats on the bottom.

The invention provides an improved biodegradable soil cover of the type mentioned in the preamble, which can be applied to the soil under almost all weather conditions and is therefore characterized in that the organic binder comprises alginate.

Alginate already has binding properties in an aqueous suspension, as a result of which washing out of the soil cover, which can thus also be applied to the soil as a suspension, does not take place or takes place to a much lesser extent.

"Soil" includes the type of soil that is suitable for agricultural purposes, for example. The term "biodegradable" means that the material in question loses its strength ^ R and coherent character over time as a result of the action of micro-organisms and / or due to weather influences and may eventually fall apart, ^ R which causes the formed film to decay and to be incorporated in a simple manner into the soil, which time is preferably less than 1 year, more preferably less than 6 months and most preferably less than 3 months. the correct choice of the fibers, the disintegrated non-woven material can even serve as a food source II for plant growth and the non-woven material can also be processed intact after use in the soil, whereby it can serve as a food source.

For this purpose the material may already contain, for example, supplementary fertilizers. The advantage of a biodegradable soil cover H according to the invention also lies in the fact that it can be sprayed as an H liquid medium, preferably an aqueous medium, such as an aqueous H suspension, on the land on which the desired H crops have already been washed. to grow. After application, a contiguous membrane will form, thus preventing the growth of weeds and unwanted plants. Such a biodegradable soil cover is an excellent alternative to the plastic foils that have been customarily used so far and which is explained in strips over agricultural soils.

Preferably, the alginate in the ground cover is cross-linked with a cross-linking agent comprising divalent cations. It is known that alginate can be cross-linked with divalent cations; such a cross-linking forms a sturdy structure that can be sufficiently resistant to mechanical stress. The ground cover can even be strong enough to support a person without damage.

The cross-linking agent preferably comprises Ca 2+ ions. Of the divalent ions, it has been found that calcium is the most suitable and allows optimum cross-linking of the alginate.

By biodegradable fibers is meant, as already explained above, fibers which, as a result of the action of microorganisms and / or due to weather influences, lose their strength and coherent character over time. The fibers are preferably of vegetable and / or animal origin.

"Fiber of vegetable and / or animal origin" means all fibers that can be extracted and / or produced from animal or vegetable material. Suitable fibers are I 1 Π OO c * <9 - - 3 - including coconut fibers, sisal fibers, wheat straw, rice straw, maize fibers, carpok, flax, linen, cotton, hemp, jute, ramie fiber, wood fibers, paper fibers, cellulose fibers, dung fibers, animal fibers, such as wool, pet and livestock hair, collagen fibers, etc. Preferably, the fibers are selected from the group consisting of wood fibers, paper fibers, cellulose fibers, manure fibers, fibers from plants, or a combination of two or more thereof . Such fibers are inexpensive, provide the cover with sufficient strength and, after degradation of the soil covering material, form fertilizers for the soil.

Preferably the fibers have a length between 50-1000 μπί.

Since the ground cover is preferably applied in the form of a liquid medium, in particular an aqueous medium, it is important that such a medium is readily pumpable without the risk of clogging of the pump installation being present. For fibers 15 above 1000 μπι, powerful, expensive and heavy pump installations are required that are difficult to handle on land. It has been found that with a fiber length between 50 and 1000 μιη the pumpability of the medium is good, even in simple spraying installations, which are used, for example, for spraying crops with agricultural pesticides. For this purpose, the fibers preferably have a length between 100-700 μπι, even more preferably between 100-500 μιη and most preferably between 100-300 μια.

In an attractive embodiment of the invention, the ground cover comprises a light-inhibiting means. By "light-inhibiting means" it is meant that when the means is included in the ground cover, less light is transmitted through the cover towards the bottom. Preventing light transmission prevents unwanted growth of, for example, weeds and other unwanted plants. Light inhibiting means are, for example, dyes and pigments, with which light of different wavelength can be selectively transmitted or retained. Examples of this are carbon, which results in a black color. With sufficient absorption of carbon, total light absorption can be obtained. The skilled person will be able to choose the desired amount of carbon for the intended effect.

Suitable carbon sources are known to those skilled in the art, such as Norit AA, CN3, SA2 (Norit, the Netherlands). Other suitable dyes and pigments are known to those skilled in the art; examples of this are tartrazine (yellow),. O o O r Λ A - Η - 4 - Η erythrosine (red), indogitine (blue), chlorophyllin (green). Combinations of pigments or dyes can also be used in H.

The ground cover can also contain dyes to give the cover material a base color, so that the material does not stand out negatively in the landscape. It is also possible to choose one or more eye-catching colors, in order, for example, to distinguish plots from each other.

The ground cover according to the invention is water-permeable, as a result of which the soil receives sufficient moisture and can have a desired inhibitory and / or selective effect with regard to the transmission of light, depending on the absorption of a light-inhibiting agent and the concentration thereof.

Depending on the choice of fibers, the air permeability of the ground cover material can also be controlled.

With large fibers, the air passage will be greater over time than with a covering material of shorter fibers. For the correct consistency of the covering material, however, one can also opt for a mixture of fibers of different sizes.

It has been found that a strong soil cover can already be obtained with a thin film of 0.5 mm. Such a layer thickness has been found to be sufficiently resistant to mechanical influences from outside (such as, for example, hail or heavy rain) and exhibits good walkability. Thicker skins are also possible, but less attractive from a cost perspective.

The invention further relates to a method for applying a biodegradable soil cover to the H surface of a soil, comprising the steps of: I a) preparing at least a first and second liquid I medium wherein the first medium is biodegradable fibers comprises I and the second medium comprises alginate, b) applying the media prepared in a) to the bottom.

As already indicated above, with such media that are preferably aqueous media, an excellent biodegradable soil cover can be formed of sufficient strength and resistance, which moreover has the desired air and water permeable properties. The media can be prepared in a manner known in the art and can be prepared in known manner on the cover to be covered. ς 1 1 - 5 - soil can be applied, such as by spraying, spraying, etc.

The first and the second medium are preferably combined during the preparation step. The combining can take place by separately preparing and subsequently combining the first and second medium, but preferably a combined first and second medium is prepared by incorporating the biodegradable fibers and the alginate in a common liquid medium. The first and the second medium, as well as the common medium, are preferably aqueous media. By taking the first and the second medium together, they can be applied in one step to the bottom to be covered by, for example, spraying, atomizing, etc. However, it is also possible to apply the first and second medium separately to the bottom, wherein it is then preferred to apply the first medium prior to or simultaneously with the second medium.

In an attractive embodiment, step a) further comprises preparing a third liquid medium comprising divalent calcium ions. As already explained above, the Ca 2+ ions act as a crosslinking agent for the alginate present in the second medium. As a result, a ground cover is obtained in which the alginate is cross-linked, whereby the load-bearing capacity of the ground cover is increased. It is noted that an attractive ground cover can already be obtained without the presence of cross-linking agent, which can be quickly broken down and easily incorporated into the soil.

When a third medium comprising divalent calcium ions is used, in an attractive embodiment of the method according to the invention, step b) comprises the steps: b1) applying the first medium and the second medium to the bottom to be covered, and b2) applying the third medium to the bottom obtained in step b1).

Although the media used can be applied separately or in combination to the bottom, it is advantageous to apply the third, calcium-containing medium to the bottom separately from and after the first and second medium. The first and second medium are applied to the bottom, whether or not combined, after which the 1022511 H third medium is applied to it separately. As a result, the calcium cross-linking agent is only brought into contact with the alginate when the alginate has already been applied to the bottom, so that premature cross-linking which could take place prior to the application of the medium to the bottom is prevented. However, it is also possible to combine the second alginate-containing medium and the third calcium-containing medium prior to step b), optionally also with the first fibrous medium, in which case H must be ensured that cross-linking is essentially not effected prior to application to the bottom because a medium containing cross-linked alginate can become difficult to process due to increased viscosity.

In another preferred embodiment, at least the first and the third medium are combined. In this embodiment the fibers and the calcium ions are jointly applied to the bottom to be covered, after which the alginate-containing medium can be applied to it. Accordingly, step b) of a further attractive embodiment of the method comprises the steps of: b1) applying the first medium and the third medium to the bottom to be covered, b2) to the bottom obtained in step b1) applying the second medium.

In this embodiment the fibers and the calcium ions are applied to the bottom and thus no cross-linking is possible yet.

Subsequently, the alginate-containing medium is applied to this, after which cross-linking can take place to obtain the ground cover according to the invention.

When the media are applied separately to the bottom, it is preferable to apply the fibrous first medium prior to the remaining media.

The first medium, or the first medium, combined with the second and / or third medium preferably contains 60/100 g of dry substance / 1 medium. With a higher dry matter content, the medium to be applied becomes thick, making it less pumpable. Below a content of 60 g / l a medium of lower viscosity is obtained, as a result of which deformation of a homogeneous contiguous membrane can be problematic. The medium preferably contains 70-85 and most preferably 75-80 g of dry matter per liter of medium.

I 1 0? ? ς 1 I - - 7 -

The second medium, or the second medium, at least combined with the first medium preferably comprises 2-40 w / w%, most preferably 5-15 w / w% alginate. The alginate preferably comprises a mixture of alginate with a high "G-block" content and alginate with a high "M-block" content. "G block" and "M block" are terms known in the art; "G block" refers to a portion from the alginate molecule that comprises polyguluronic acid and forms solid gels. "M block" refers to a portion in the alginate that comprises polymanuronic acid and forms elastic gels. Such alginates are known to those skilled in the art, such as Manugel DMB (with an M block: G block content of 30:70) and Manucol DM (with an M block: G block content of 60:40). Manugel and Manucol are trade names of Kelco Ine, USA. The ratio of these alginates also determines the firmness and flexibility of the non-woven fabric. With a view to the intended firmness and flexibility of the soil covering fleece, the correct ratio can be determined and / or determined in a simple manner by choosing the correct combination of the G block content and the M block content in the alginate.

The third medium, or the third medium, at least combined with the first medium preferably comprises 0.1-0.4 w / w%, most preferably 0.15-0.25 w / w% Ca 2+ ions to crosslink the alginate.

In particular when the calcium ion-containing third medium is combined with the second alginate-containing medium prior to step b), the alginate present above 0.4 w / w% of Ca 2+ ions will be rapidly crosslinked, thereby forming a homogeneous membrane becomes more difficult and can even cause clogging of spraying installations. However, when the Ca 2+ ion content is below 0.1 w / w%, the cross-linking leads only to a lesser extent to reinforcement of the ground cover material.

The first, second or third medium, or a combination thereof, can also comprise additional means, such as buffer substances for buffering any pH differences in the soil or the pH of different soils. The pH of the suspension is preferably 5-6 and the suspension is preferably buffered in this pH range. The skilled person will know suitable buffer substances, such as K 2 HPO 4, NaH 2 PO 4. For example, fillers can also be included in the suspension 102251 1 H such as kaollne. The suspension preferably contains 60-100 g of dry matter per liter of suspension.

In a preferred embodiment, at least the first, second or third medium or a combination thereof comprises a cross-linking agent. By incorporating such an agent it is ensured that the alginate can be properly mixed with the divalent ions, without the crosslinking occurring so rapidly that processing is no longer possible. This is particularly important when the second and third, and possibly also the first, medium 10 are combined prior to step b). A cross-linking agent makes a longer processing time possible. Cross-linking agents are known in the art. Preferably these agents are selected from the group selected from EDTA (ethylene diamine tetraacetic acid), phosphates such as sodium tripolyphosphate, sodium hexametaphosphate, citrates such as trisodium citrate.

As already stated above, a layer thickness of 0.5-5 mm, even more preferably of 0.5-2 mm, is applied.

In order to obtain the desired layer thickness, the media is preferably applied in an amount of 8-15 m3 per hectare of soil in step b).

Preferably, step b) comprises spraying the media on the bottom to be covered.

As explained above, the first, second and third medium may be applied separately to the bottom, or may be combined with each other prior to step b) as desired. When applying at least two of the first, second and third medium separately, it is advantageous to use a spraying installation with two or more spray heads, wherein, for example, the first medium combined with the second medium is sprayed from one spray head 30, and wherein the third medium is sprayed simultaneously or sequentially from the other spray head. It is thus also possible to combine the first medium with the third medium and spray it from a first spray head, while the second medium is sprayed from a second spray head. The first, second and third medium can also be applied to the bottom from three separate spray nozzles.

1 η ?? ς 1 1 - 9 -

The invention further relates to a dry powdered mixture for the manufacture of a ground cover comprising alginate and biodegradable fibers, for example for the production of a ground cover according to the invention. Such a dry powdered mixture is easy to handle and to put on the market. The user only needs to add water to obtain a desired suspension for the production of the soil cover.

In another embodiment, the invention provides a dry powdered mixture for manufacturing a ground cover, which mixture comprises a divalent calcium salt and biodegradable fibers. Only an alginate-containing liquid medium, preferably an aqueous medium, must be added to this mixture, as a result of which a cross-linkable bottom cover according to the invention can be formed. It is also possible to add powdered alginate and an aqueous medium, such as water, to this powdered mixture to obtain a suspension that can be applied to the bottom to be covered.

Preferably the mixture according to the invention comprises 60-98 w / w%, preferably 85-95 w / w% biodegradable fibers. Furthermore, the mixture preferably comprises 20-40 w / w% alginate, most preferably 5-15 w / w% alginate.

In another attractive embodiment the mixture comprises 0.4-1.5 w / w%, preferably 0.6-1.0 w / w% calcium salt, preferably an inorganic calcium salt, and even more preferably calcium hydrogen phosphate, preferably CaHPO 4 .H 2 O. It is preferable to opt for a calcium salt that is less soluble, whereby Ca 2+ is slowly released into the suspension, so that the alginate is cross-linked less quickly and the suspension can thus be processed for longer. CaHPO 4 .H 2 O is an example of this.

The dry powdered mixture according to the invention preferably comprises both biodegradable fibers, and alginate and a divalent calcium salt.

In a further embodiment, the mixture comprises a cross-linking retardant, as already discussed above.

The mixture can also comprise a light-inhibiting agent, for example in the form of a dye.

The invention also relates to the preparation of a biodegradable soil cover suspension, comprising the incorporation of a mixture according to the invention in an aqueous medium.

Preferably, 60-80 g of mixture per liter of aqueous medium is taken up, more preferably 70-85 g of mixture per liter of aqueous medium, and most preferably 75-80 g of mixture per liter of aqueous medium.

The invention will be explained in more detail below with reference to examples which are not intended to limit the invention.

10 Examples

Example 1 a) preparation of dry basic mixture 15 cotton fiber 25% wood fiber 45% I kaolin 15% alginate mixture 10% I phosphate buffer 5% The components were mixed to a homogeneous mass.

b) preparation of suspension

925 liters of water were pumped into a tank (1500 liters) equipped with a stirrer. With good stirring, 75 kg. dry base mixture suspended.

C) applying the soil cover the suspension tank was placed on an agricultural tractor and the suspension was driven at a constant speed via a tube with nozzles (4 mm. Flat radius) the width of the area to be covered, with a pressure of approx. 4-6 bar applied to the bottom H.

The desired layer thickness could be set with the tractor speed and nozzle pressure.

Via a second spray system, parallel to the first, a 5% CaCl 2 solution was sprayed onto the first layer, whereby direct fixation (cross-linking) of the first layer takes place.

I 1 '1 Ί - 11 -

The layer thus formed follows the contours of the bottom surface and thus ensures effective coverage.

The layer is water-permeable and selectively light-permeable depending on the pigment used.

The layer is stable during the growing time of the crop and resistant to a certain mechanical load. After the growing time, the layer can be mixed with the soil, after which micro-organism degradation occurs. Example 2 a) preparation of the dry basic mixture cotton fiber 25% wood fiber 45% kaolin 4.75% alginate mixture 10% phosphate buffer 5%

CaHPO 4 .H 2 O 10%

Sodium hexametaphosphate 0.25%

The components were mixed to a homogeneous mass.

B) preparation of suspension

The suspension was prepared according to Example 1.

c) application See example 1, but without after treatment with CaCl 2

The first layer was applied according to Example 1, no Ca 2 * -containing solution was sprayed. In contrast to Example 1, where direct gelation took place, a gradual gelation occurred, which was completed after about 1 hour.

This gradual gelation provides an improved adhesion of the cover layer to the bottom. The quality and strength of the layer is comparable to that of example 1.

1022511 Η Η Example 3 Η a) preparation of dry basic blend H cotton fiber 25% Η wood fiber 45% Η kaolin 15% Η CaS04.2Η20 10% Η 10 phosphate buffer 5% I b) preparation «suspension Η 75 kg. dry basic mixture was partitioned H in 925 kg with good stirring. water c) preparation alginate mix alginate mixture 10% wood fiber (maximum length 500 μσι) 90% I 20 d) preparation alginate suspension 10 kg. mixture under c) was stirred in 200 kg with good stirring.

water divided.

stirring was continued for an additional 10 minutes for optimum distribution.

E) application in the same manner as in example 1) the suspension according to b) was applied to the bottom.

The suspension according to d) was sprayed on this layer, so that a thin gelled film was formed which adhered well to the underlying bottom, was water-permeable and, after drying, formed a firm, closed covering layer, which had sufficient elasticity and was tear-resistant.

I 1 Λ r <Ί1.

Claims (39)

CLAIMS 1. Biodegradable soil cover, formed by a nonwoven, which conforms to the shape of the surface of the soil, comprising biodegradable fibers connected with an organic binder, characterized in that the organic binder comprises alginate. A soil cover according to claim 1, characterized in that the alginate is cross-linked with a cross-linking agent comprising divalent cations. 3. Ground cover according to claim 2, characterized in that the crosslinking agent comprises Ca 2+ ions. 4. Ground cover as claimed in any of the foregoing claims, characterized in that the fibers are of vegetable and / or animal origin, preferably selected from the group consisting of wood fibers, paper fibers, cellulose fibers, manure fibers, fibers from plant residues or a combination of two or more thereof. 5. Ground cover as claimed in any of the foregoing claims, characterized in that the fibers have a length between 50-1000 μία. 25 6. Ground cover as claimed in claim 5, characterized in that the fibers have a length between 100-700 μία. 7. Ground cover as claimed in claim 6, characterized in that the fibers have a length between 100-500 μία. 8. Ground cover as claimed in claim 7, characterized in that the fibers have a length between 100-300 μια. A ground cover according to any one of the preceding claims, characterized in that it comprises a light-inhibiting means. 1 022 s 1 1 Η 10. Ground cover according to one of the preceding claims, characterized in that the fleece has a thickness of 0.5-5 mm. 11. Ground cover as claimed in claim 10, characterized in that the fleece has a thickness of 0.5-2 mm. 12. Method for applying a biodegradable soil cover to the surface of a soil, comprising the steps of: a) preparing at least a first and second liquid H medium wherein the first medium comprises biodegradable fibers and the second medium comprises alginate , b) applying the media prepared in a) to the soil. 13. Method as claimed in claim 12, wherein during step a) at least H at least the first and the second medium are combined. The method of claim 12 or 13, wherein step a) further comprises preparing a third medium comprising divalent calcium ions. 15. Method as claimed in claim 14, wherein step b) comprises the steps of: b1) applying the first medium and the second medium to the bottom to be covered, and b2) applying to the bottom obtained in step b1) the third medium. The method of claim 14, wherein during step a) at least the first and the third medium are combined. 17. Method as claimed in claim 14 or 16, wherein step b) comprises the steps of: b1) applying the first medium and the third medium to the bottom to be covered, b2) on the bottom, obtained in step b1), applying the second medium. 1 0225 1 1 - 15 - A method according to any one of claims 12-15, characterized in that the first medium, or the first medium combined with the second and / or third medium, contains 60-100 g of dry matter / 1 medium. A method according to claim 18, characterized in that the first medium or the first medium combined with the second and / or third medium contains 70-85 g, preferably 75-80 g of dry matter / 1 medium. 20. A method according to claim 16, characterized in that the second medium or the second medium, at least combined with the first medium, comprises 2-40 w / w%, preferably 5-15 w / w% alginate. 21. Method as claimed in any of the claims 12-20, characterized in that the third medium or the third medium is at least combined with the first medium 0.1-0.4 w / w%, preferably 0.15-0 25 w / w% Ca 2+ ions. 22. A method according to any one of claims 18-21, characterized in that at least one of the first, second or third medium comprises a cross-linking agent. The method according to claim 22, characterized in that the cross-linking agent is selected from the group consisting of EDTA, phosphate, citrate. 25 The method according to any of claims 12 to 23, characterized in that a layer thickness of 0.5-2 mm is applied in step b). 25. A method according to any one of claims 12-24, characterized in that the media is applied in step b) in an amount of 8-15 m3 per hectare of soil. 26. Method as claimed in any of the claims 12-25, characterized in that step b) comprises spraying at least one of the media on the bottom to be covered. 27. Dry powdered mixture for the manufacture of a ground cover comprising alginate and biodegradable fibers. 1 02251 1- I - 16 - A dry powdered mixture for producing a soil cover comprising a divalent calcium salt and biodegradable fibers. A blend according to claim 27 or 28, characterized in that the blend comprises 60-98 w / w%, preferably 85-95 w / w% biodegradable fibers. The mixture according to any of claims 27 to 29, characterized in that the mixture comprises 2-40 w / w%, preferably 5-15 w / w% alginate. The mixture according to any of claims 27 to 30, characterized in that the mixture comprises 0.4-1.5 w / w% of a divalent calcium salt. The mixture according to claim 31, characterized in that the mixture I comprises 0.6-1.0 w / w% of a calcium salt. 33. A mixture according to claim 31 or 32, characterized in that the calcium salt comprises calcium hydrogen phosphate. The mixture according to any of claims 27 to 33, characterized in that the mixture comprises a cross-linking retardant selected from the group EDTA, phosphates, citrates or a combination thereof. 25 The mixture according to any of claims 27 to 34, characterized in that the mixture comprises a light-inhibiting agent. 36. A method for the preparation of a biodegradable soil cover suspension, comprising incorporating a mixture B according to any of claims 27-35 in an aqueous medium. A method according to claim 36, characterized in that 60-100 g of mixture is taken up per 1 B of aqueous medium. B The method according to claim 37, characterized in that 70-85 g of mixture is taken up per 1 B of aqueous medium. I 1 Π 9 9 c 1 <- Λ * - 17 - A method according to claim 38, characterized in that 75-80 g of mixture is taken up per 1 aqueous medium. 1 Ω? ? ς 1 t -