AGRICULTURAL MULCH FILM

Abstract

An agricultural mulch film including two or more layers with different capacities of light absorption and being separable from each other, e.g. by degrading at different speeds and/or having different times of degradation.

Claims

1. An agricultural mulch film comprising: a first layer having a first capacity of light absorption, and a second layer, having a second capacity of light absorption different from the first capacity of light absorption, and wherein the first layer is configured to be removed from the second layer after a period of time.

2. The agricultural mulch film according to claim 1, wherein the first layer has a first degradation time, and the second layer has a second degradation time, the second degradation time being different from the first degradation time.

3. The agricultural mulch film according to claim 2, wherein the first layer has a first rate of degradation, and the second layer has a second rate of degradation, which is different from the first rate of degradation.

4. The agricultural mulch film according to claim 1, wherein the first layer is a top layer of the film, and the second layer is a bottom layer of the film.

5. The agricultural mulch film of claim 4, wherein the top layer has a shorter degradation time than the bottom layer.

6. The agricultural mulch film of claim 4, wherein the top layer is biodegradable and the bottom layer comprises polyolefinic materials.

7. The agricultural mulch film of claim 4, wherein the top layer is configured to be removable from the film.

8. The agricultural mulch film of claim 1, wherein the first layer is of a first color and the second layer is of a second color different from the first color, one of the first and second layers being white or silver and the other of the first and second layers being black.

9. The agricultural mulch film of claim 1, further comprising a third layer.

10. The agricultural mulch film according to claim 9, wherein the film has an A/B/B structure.

11. The agricultural mulch film according to claim 1, wherein a thickness of the film is between 10-200 microns.

12. The agricultural mulch of claim 1, wherein one or the first layer and/or second layer is biodegradable and/or compostable having a degradation time between one and nine months.

13. The agricultural mulch of claim 1, wherein the first layer and/or second layer includes polyolefins.

14. The agricultural mulch film of claim 1, wherein the first layer and/or second layer comprises a plurality of sublayers.

15. The agricultural mulch of claim 1, further including one or more pockets along one or more edges of the mulch film.

16. An agricultural mulch film comprising: a first layer of a first color, and a second layer of a second color different from the first color, wherein the first layer has a degradation time shorter than a degradation time of the second layer.

17. The agricultural mulch film of claim 16, wherein the first layer is a top layer of the film.

18. The agricultural mulch film of claim 17, wherein the top layer is biodegradable.

19. The agricultural mulch film of claim 17, wherein one of the first and second layers is black when the other of the first and second layers is white or silver.

20. The agricultural mulch film of claim 16, further comprising a plurality of pockets at least along the longitudinal edges of the mulch film.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0037] Non-limiting examples of the present disclosure will be described in the following, with reference to the appended figures, in which:

[0038] FIG. 1 schematically represents a cross-section of an agricultural mulch film according to an example.

[0039] FIG. 2 schematically illustrates a degradation of an upper layer of an agricultural mulch film according to an example.

[0040] FIG. 3 schematically shows how an upper layer may be removed from an agricultural mulch film according to an example.

[0041] FIG. 4 schematically represents a cross section of an agricultural mulch film according to another example.

[0042] FIG. 5 schematically illustrates an example of an agricultural film for use with asparagus.

[0043] FIG. 6 schematically illustrates a top view of an agricultural mulch film according to an example.

[0044] FIG. 7 schematically illustrates a section of the agricultural mulch of FIG. 5.

[0045] The figures refer to example implementations and are only be used as an aid for understanding the claimed subject matter, not for limiting it in any sense.

DETAILED DESCRIPTION

[0046] FIG. 1 schematically represents a cross-section of an agricultural mulch film 100. The agricultural mulch film 100 includes a first layer 110 and a second layer 120. The first layer 110 may be a top layer, i.e. the layer of the mulch film 100 configured to be placed facing upwards, e.g. facing the sky and/or the sunlight. In this example, the second layer 120 is a bottom layer, i.e. the layer configured to be placed facing downwards, e.g. facing the soil. The first layer 110 and the second layer 120 have different capacities of light absorption, and the first layer 110 and the second layer 120 have different times or speeds of degradation.

[0047] The fact that the top 110 and bottom 120 layers of the mulch film 100 may degrade at different speeds means that the optical and/or thermal properties of the film 100 can change over time due to the difference in capacity of light absorption of each layer.

[0048] For instance, in some examples, the time and/or speed of degradation of the top layer 110 may be higher than the time and/or speed of degradation of the bottom layer 120. Therefore, the top layer 110 may degrade, as schematically illustrated in FIG. 2, and the bottom layer 120 may become exposed to sunlight after a given period of time. As the top 110 and bottom 120 layers have different capacities of light absorption, the optical and/or thermal properties of the mulch film 100 change with the degradation of the top layer 110. The light and/or heat reaching the soil may thus be adapted to the needs of the crop and/or climate conditions.

[0049] In some examples, the top layer 110 may degrade due to its composition, e.g. due to being made of biodegradable materials. Some biodegradable materials may further be compostable. In these or other examples, the top layer 110 may degrade due to the action of ultraviolet (UV) radiation. In some examples, the bottom layer 120 may be made of, or based on, polyolefinic plastic materials.

[0050] In another example, shown in FIG. 3, the top layer 110 may be configured to be removable from the film 100. Detaching the top layer 110, e.g. manually, enables changing the properties of the mulch film 100 without having to wait for the top layer 110 to degrade. The examples of FIGS. 2 and 3 may be combined, i.e. a layer, e.g. the top layer 110, may be biodegradable and also detachable.

[0051] In an example, a mulch film 100 such as the mulch film 100 of the examples of FIGS. 1-3, the top layer 110 may be white or silver and the bottom layer 120 may be black. Therefore, the top layer 110 may reduce the temperature below the film 100 and reflect sunlight until it degrades or is detached. When the darker bottom layer 120 is at least partially uncovered, the bottom layer 120 instead will absorb incoming light and thereby may increase the temperature below the film 100. Accordingly, this mulch film 100 may be used for crops growing towards the winter.

[0052] The opposite may be implemented for crops growing towards the summer, i.e., the top layer 110 may be black and the bottom layer 120 may be white or silver, so that at the appropriate time, the appropriate reflectivity and light absorbance are used.

[0053] In general, the top 110 and bottom 120 layers may be of any color, they do not need to be white, silver or black. Any suitable color pigment may be added to the different layers.

[0054] For instance, in some examples the bottom layer is black, and the top layer may be green, brown, grey, transparent, or of any color different from black. Likewise, in some other examples, the top layer is black, and the bottom layer may be of any color which is not black.

[0055] FIG. 4 schematically shows another example of agricultural mulch film 100. In this example, the film 100 further comprises a third layer 130 below the second layer 120. In this example, layer 130 is the bottom layer, which in use is facing the soil.

[0056] In the example of FIG. 4, the speed and/or time of degradation and the capacity of absorption of each layer 110, 120, 130 may be configured to achieve the desired outcome.

[0057] In some examples, the speed of degradation decreases from the top layer 110 to the bottom layer 130. In this way, each of the three layers 110, 120, 130 may be exposed to sunlight with time and the properties of the mulch film 100 may be varied accordingly. In an example, the first 110 and second 120 layers are made of biodegradable materials and the third layer 130 is made mostly or exclusively of polyolefinic materials.

[0058] In some other examples, the third layer 130 has a speed and/or time of degradation substantially equal to the speed and/or time of degradation of the second layer 120. Such a mulch film 100 may then have an A/B/B structure. In an example, the first (top) layer 110 may be black, the second (middle) 120 layer may be white or silver, the third (bottom) 130 layer may be black, and the top layer 110 may degrade faster than the layers 120 and 130. Accordingly, the upper layer 110 may be configured to absorb irradiant (sun)light to increase the temperature below the film 100 first, and a bicolor film may remain when the top layer 110 is no longer present. The middle layer 120 may then reduce the temperature below the film 100 and reflect light towards the crop, and the bottom layer 130 may hamper weeds growth. Therefore, this mulch film 100 may be advantageous for crops growing towards the summer.

[0059] A mulch film 100 such as the one described in the paragraph above may provide additional advantages. This may be seen in FIG. 5. In FIG. 5, an asparagus 500 is growing below a mulch film 100 and pushing the film 100 upwards. The pressure exerted by the tip of the spear contributes to the fragmentation or breaking of the top black layer 110 weakened by degradation. Therefore, for an asparagus crop, or a crop which may affect the mulch film 100 in a similar way, the middle white or silver layer 120 becomes visible, e.g. in the form of white spots. Accordingly, which asparagus may need to be picked up may be easily seen, facilitating collection and increasing its efficiency. Additionally, the tips of the spears do not overheat.

[0060] In yet a further example, the bottom layer 130 has a speed of degradation substantially equal to the speed of degradation of the top layer 110, and the middle layer is substantially not degradable. Such a mulch film 100 may have an A/B/A structure. In an example, the top 110 and bottom 130 sections are silver or white, and the middle section 120 is black.

[0061] In summary, each of the layers may have specific characteristics and may be provided with a specific objective in mind. Thanks to being able to engineer the degradation rate and/or time of the separate layers, a mulch film may be provided that can vary its characteristics over time.

[0062] In any of the examples of FIGS. 1-5, the upper layer 110 may have a degradation time between one and nine months, and more in particular between three and six months. This range of degradation times enables to adapt the optical and/or thermal properties of a mulch film 100 to the growth times of different types of crops, and also to different climate conditions, e.g. due to season change. Other layers of the mulch film 100 may have degradations times in this range too.

[0063] A non-biodegradable layer or less biodegradable layer may have a degradation time that is longer than a degradation time of a degradable layer, e.g. more than 1 year.

[0064] Concerning (bio)degradability, a biodegradable layer, e.g. the upper layer 110, may include one or more of the following materials: polylactic acid (PLA), poly(butylene adipate-co-tereftalate) (PBAT), polyhydroxyalkanoates (PHA), polyhydroxybutyrate (PHB), polyhydroxyvaleriate (PHV), polyhydroxyhexanoate (PHH), butyrate-co-valerate (PHBV or P(3HB-co-3HV)), butyrate-co-hexanoate (PHBH or P(3HB-co-3HH)), starch and/or starch blends, poly (butylene succinate) (PBS), poly (butylene succinate-co-adipate) (PBSA) and polymers derived from proteins, e.g. milk proteins.

[0065] A non-(bio)degradable or less (bio)degradable layer of the mulch film 100 may include one or more of the following materials: polyethylene (PE), PE copolymers, polypropylene (PP), PP copolymers, ethylene vinyl acetate (EVA), ethylene butyl acrylate (EBA), polyamide (PA), ethylene vinyl alcohol (EVOH), polyvinyl alcohol (PVOH), polyethylene terephthalate (PET).

[0066] In an example, amounts of PBAT, PLA and/or starch are used to adjust the biodegradability of a layer, e.g. a top layer 110. The proportions of these materials may affect a degradation time and/or degradation speed of a layer. For instance, by varying the proportions of these materials, a degradation time between one and three months may be obtained.

[0067] Any of the layers of the mulch films 100 according to the present disclosure, may comprise one or more of the materials mentioned in the above paragraphs. In addition, one or more adhesive polymers may be added to the mulch film 100 to guarantee adherence between layers. In an example, maleic anhydride is included with one or more of the above polyolefinic plastic materials.

[0068] Also, the first, second and third layers 110, 120, 130 (and further layers) may be monolayer or multilayer, i.e. the layers may include sublayers. The first, second, and third layers may have a same or a different number of sublayers. The thickness of the layers included in the mulch film 100 may be different or the same. In the examples of FIGS. 1-3, the thickness of the top 110 and bottom 120 layers is different. In some other examples, the thickness of the top 110 and bottom 120 layers may be substantially the same. In the example of FIGS. 4 and 5, the top 110 and bottom 130 layers have a substantially same thickness which is lower than the thickness of the middle layer 120. In some other examples, the top 110, bottom 120 and middle 130 layers may have a substantially same thickness.

[0069] The number of layers, the materials used for each layer and the thickness of each layer may be selected according to desired properties of each layer, e.g. in terms of biodegradability. Additives may also be included to obtain the desired properties of a layer. A mulch film 100 may have more than three layers.

[0070] In an example, the total thickness of the mulch film 100 may be between 10 and 200 microns. In such an example, the mulch film 100 may have the following mechanical properties.

TABLE-US-00001 EXAMPLE OF MECHANICAL PROPERTIES Magnitude Value Unit Standard Thickness  10-200 Microns ISO 4591 Tensile strength at break Longitudinal direction 14-35 MPa EN ISO 527-3 Transversal direction 14-40 MPa EN ISO 527-3 Tensile strain at break Longitudinal direction  80-800 % EN ISO 527-3 Transversal direction  100-1200 % EN ISO 527-3 Impact resistance Machine direction (MD)  50-800 g ISO 7765-1

[0071] In such an example, a biodegradable layer comprised in the mulch film 100 may have a thickness between 2 and 100 microns. For instance, in FIG. 4 layer 110 may be biodegradable and it may have a thickness of 10 microns. In this example, layers 120 and 130 may be based on polyolefinic materials and each of them may have a thickness of 35 microns. Therefore, the mulch film 100 may have a total thickness of 80 microns in this example.

[0072] In an example, the top layer may be black (or another color with low reflectance and relatively high absorbance of light), the middle layer may be white, and the bottom layer may be black. After degradation of the top layer, the remaining layer may have a top white layer, and a bottom black layer.

[0073] A mulch film 100 according to any of the examples disclosed herein may be manufactured in several ways. In an example, the mulch film 100 may be manufactured by coextruding two or more layers or sublayers including any of the materials mentioned above. For example, one or more types of polymer pellets may be melted and shaped into a layer or sublayer. Additives, such as coloring agents, may be melted with the pellets. Two or more layers or sublayers may be then coextruded to manufacture the mulch film 100. Such a coextrusion process may include blowing and/or calendaring, as well as orientation of the film. The film may be oriented in a longitudinal direction (machine direction) and/or a transversal direction. In another example, two or more layers or sublayers including any of the materials mentioned above may be stacked together by lamination, e.g. adhesive lamination or hot-roll lamination. Other manufacturing processes may be possible.

[0074] FIGS. 6 and 7 schematically illustrate a top view and a cross sectional view, respectively, of an agricultural mulch film 100 with pockets 200 along two of the edges of the mulch film 100, e.g. along a longitudinal direction of the mulch film 100. Pockets 200 may be filled with soil, land and/or moisture absorbing substances to avoid the movement of the mulch film 100 with respect to the cultivation area. In general, any number of pockets may be included to any number of edges or laterals of the mulch film 100.

[0075] In a preferred example, the pockets may be integrally formed with the film.

[0076] Although only a number of examples have been disclosed herein, other alternatives, modifications, uses and/or equivalents thereof are possible. Furthermore, all possible combinations of the described examples are also covered. Thus, the scope of the present disclosure should not be limited by particular examples, but should be determined only by a fair reading of the claims that follow.