The invention refers to a plastic film used for covering linearly cultivated plantations (asparagus, strawberries etc) and for plantations cultivated under small tunnels. Its main characteristic is that it has along its sides a super absorbing material, which can absorb water thus increasing its weight considerably. The plastic film can be applied on the field and it can be sprayed with water either by natural or artificial rain or by any other means. The spayed water is absorbed by the super absorbing material hence increasing the weight along the sides of the plastic film, which is consequently fixed on the line of cultivation.

Up to now several solutions for plastic films that can incorporate weight have been proposed. In most cases weight is simply in the form of soil. All these proposals aimed at presenting a plastic film in which soil can be incorporated so that it can be fixed on the cultivation line. At the same time the cultivation line should be easily uncovered so that the cultivation processes can be easily performed.

This technique has resolved several complications of the existing mulching and low tunnel cultivation methods however both these methods have considerable drawbacks. Despite the fact that soil is probably the cheapest material that can be used as fixing weight it requires high labour cost to fill the plastic film with it.

Furthermore the prevailing bad weather conditions during the time of the year that the film is applied on the field make labour a scarce resource. Hence despite the success of this method there is an ardent demand of the market to replace it with an easier and cheaper method.

An alternative solution proposed by the same inventor in patent GR 1002872, comprised a plastic film that had water tubes at both its edges. However using the current material technology it was rather difficult for this patent to materialise since there was a relatively high risk of the film being damaged in such an aggressive environment as a field, thus causing unwanted water leakages. Therefore research

headed towards a totally different solution, avoiding the use of soil or water, and taking advantage of a stable viscous material that combines the attributes of both soil and a flowing medium such as water.

The result of these research efforts is the current invention. According to the invention there can be a super absorbing material incorporated in a plastic film of width (A) up to 4m and of thickness up to SOON, m and any length (L). The super absorbing material can absorb considerable amounts of water relative to its weight (super absorbing material weight to absorbed material weight 1: 5 to 1: 1000) thus forming a viscous agglomerate of water and super absorbing material.

These super absorbing materials are known as superabsorbers and are commonly polymeric and more specifically polyacrylates or polyacrylate amides. If this super absorbing material is sprayed with water either by natural or artificial rain or by artificial water insertion means, it absorbs water and increases its weight and its volume according to the aforementioned ratio. Hence the average weight per metre square of the film can be increased and the film can be fixed on the cultivation line.

These materials have the ability to keep the water for a large period of time when the ambient temperature does not exceed 50 °C which is actually true for a normal field.

Moreover they are able to absorb water for more than just one time thus they can be continuously used for several years.

The advantages of this invention can be summarised in the following points: a) Applying the film on the linear cultivation becomes a very easy task. The film can be applied either using a conventional machine or even manually. Thanks to its design the rain water or water coming from any source can be led to the super absorbing material which immediately absorbs it and it swells creating the water-superabsorber agglomerate which increases the weight of the film.

Experience shows that 200-500 gr of weight per meter of film have proved to be sufficient for fixing the film on the cultivation line. The super-absorbing material increases its weight on average by 100 times (varies from 5 to 1000 times depending on the type of super absorbing material). Less than 3gr of super absorbing material per meter of film is more than enough to fix the film

on the cultivation line. These materials have the ability to keep the water for a large period of time when the ambient temperature does not exceed 50 °C.

The rain that would periodically fall will be reabsorbed by the super absorbing material thus the film's weight would not be changed b) The labour cost is minimised since there is no need to put any soil in or on the film as it is being applied on the field. c) The period of the year at which the film is applied on the field does not depend on the availability of labour. d) Weight is uniformly distributed hence no air can go underneath the film. This proves to be beneficial for two reasons. Firstly the film is more securely fixed on the cultivation line. Secondly in plantations such as the asparagus fresh air can lead to the deterioration of the quality of the harvested spears. In other words the uniform distribution of the weight blocks fresh air from reaching the asparagus spears hence high quality asparagus is harvested.

The invention is described in the following paragraphs referring to the Figures that illustrate it schematically: Figure 1 The plastic film (1) according to the first possible way to materialise the invention, in which the super absorbing material (2a) is placed on both its edges using an adhesive medium or an adhesive tape. A cross- section of the film and a cross-section of the water-superabsorber agglomerate (2al) are to be seen.

Figure 2 The plastic film (1) according to a second way to materialise the invention, where the super absorbing material (2b) is incorporated into a water permeable stripe (3) that is welded along the sides of the plastic film. A cross-section of the film and a cross-section of the water- superabsorber agglomerate (2bl) at its use with a simultaneous swelling of the water permeable stripes (3) are to be seen.

Figure 3 The plastic film (I) according to a third way to materialise the invention where the superabsorber (2c) is encapsulated in plastic, water

permeable vaults (4) along its sides. In addition a cross-section of the film and a cross-section of the water-superabsorber agglomerate (2c 1) are to be seen.

Figure 4 The plastic film (1) according to an improved version of the third way to materialise the invention, where the water permeable vault (4) is non- continuous and is separated by a transverse continuous or non continuous weld (5) forming confined water permeable vaults (4i) so that the super absorbing material (2c) cannot move freely along the length of the film (L). Similarly a cross-section of the film and a cross- section of the water-superabsorber agglomerate (2cl) is to be seen Figure 5 The plastic film (1) according to a fourth way to materialise the invention where above each water-permeable vault (4i) that encapsulates the super absorbing material (2d) there is a second vault guiding the water (8i) to the water-permeable vault (4i) that encapsulates the super absorbing material (4i). Furthermore it functions as a entrapment device for the water vapour that forms and allows the vapour to condense (4) and again to be absorbed by that super absorbing material.

In the following paragraphs several processes to materialise the invention are described.

According to the first way of materialising the invention (Figure 1) the super absorbing material is placed at a width less than 1 Ocm (2a), along both sides of a film of any length (L), width (A) smaller than 4m and thickness less than 500um produced employing any polyolefin or any combination of polyolefins (either virgin or recycled materials). It is placed either by employing some adhesive medium or by using an adhesive tape on which the super absorbing material is glued. In this case the super absorbing material is exposed to adverse weather conditions and heavy use thus it is of great importance to have it securely attached to the film so that it is not separated from the film during its lifetime. The plastic film, which has the super absorbing material along its sides, is wound into rolls that due to the existence of the super

absorbing material are bone shaped. Namely its two sides are considerably thicker than its middle part.

According to a second way of materialising the invention (Figure2) the super absorbing material (2b) is glued, wrapped or encapsulated into a water permeable tape (3) of small width so that it cannot escape from it. Such a tape can be manufactured using for example non woven materials in which the super absorbing material is uniformly distributed during the production of the tape, glued on their surface or wound into the non woven materials. The water permeable tape (3) is then glued onto the plastic film (1) in a similar manner to the one used in the first way of materialising the invention. Its main advantage is that the water can easily permeate through the tape and a water-superabsorber agglomerate (2bl) forms relatively easily thus fixing the film on the cultivation line.

According to the third way of materialising the invention (Figure 3) the super absorbing material (2c) is encapsulated into a water permeable vault (4) formed by a folding along each side of the plastic film (1) which is manufactured in exactly the same manner as the film in the first way of materialising the invention. The folding and the welding is formed in such a manner that: a) Water is guided towards the water permeable vault (4) where the super absorbing material is encapsulated (2c) passing through small openings (7) of the non continuous welding (6) ofthe film edge with the main part of the film. b) These small openings (7) of the non continuous welding (6) do not allow both the super absorbing material (2c) and the water-superabsorber agglomerate to escape outside the water permeable vault (4).

Additionally the super absorbing material (2c) as well as the formed agglomerate can be entrapped if in the above mentioned solution the water permeable vault (4) is not continuous along the whole length of the film (1) but segmented to smaller vaults at a distance of 2m for example. The segmentation can be made by transverse welds (5) at the vault forming small water permeable vaults (4.1, 4.2, etc generally 4. i) that entrap the super absorbing material (2c) (Figure 4). In this fashion the super absorbing material (2c) is entrapped hence it is ensured that a specific amount of

material per meter of plastic film exists and that it is uniformly distributed in the plastic film.

According to a fourth way of materialising the invention (Figure 5), that is an improved version of the last solution, a guiding vault (8.1, 8.2,..., 8i) is formed above each water permeable vault (4i) by means of a folding along the edge of the film and linear or non linear welds (9) of any shape guiding the water under the action of gravity towards the vaults where the super absorbing material is encapsulated (4.1, 4.2,..., 4i). Moreover this formation of vaults inhibits the loss of water vapour since it condenses and is absorbed again by the super absorbing material. The flow of water is assisted through gravity towards the respective vault that contains the super absorbing material (2d) while the water vapour is forced to condense and again-due to gravity-to be fed continuously to the water- superabsorber agglomerate (2dl) There are infinite such constructions since they are formed by a combination of welds of different shapes so that water permeable vaults are formed (4.1, 4.2,..., 4. i) that entrap the super absorbing material (2d) or the water - superabsorber agglomerate (2dl) and respective guiding vaults (8.1, 8.2,..., 8. i) that also entrap the water vapour. To avoid the excess water concentration in the two successive vaults (namely the water that cannot be absorbed by the super absorbing material) there can be small openings at the guiding vaults (8i) for example a small hole through which the excess water can escape. In this manner the weight ofthe film can be absolutely controlled.

In all previous manufacturing solutions the super absorbing material could be free to move inside the vaults. It could be glued on small patches preferably a self adhesive plastic patch of any shape for example circular, which can be glued onto the film during the manufacturing process. Is uniform distribution can be closely controlled and winding the film during production becomes an easier task.

During the use of a plastic film with the super absorbing material, used for covering linear plantations, it is enough to be wetted on its surface using natural, or artificial rain. The super absorbing material absorbs the water and by gaining weight the film is fixed upon the cultivation line.

The plastic film used for covering linear plantations having a super absorbing material along its sides that provides the necessary weight to fix the film on the cultivation line, is an innovative solution. With this method, for the first time applying a horticulture (mulching) film does not require the use of soil to be put in any kind of pockets or to cover the sides of the film with soil. Water in most cases is naturally fed to the film and the overall weight of the film can be accurately controlled by adding the required amount of super absorbing material along the sides of the film.

Furthermore it is an environmentally friendly solution since the superabsorber being a polymeric material can be recycled and reused either with the film or after it is separated from it.

The plastic film used for covering linear plantations having a super absorbing material along its sides can have any colour in each surface. Moreover by using several additives such as stabilisers and/or infrared radiation absorbers it can have specific and tailored properties. When the objective is to use the film for more than just one season the film can be collected from the field with the water-superabsorber agglomerate being in or on it, carefully packaged and stored away for the next season.