Use of composite material derived from recycling polylaminate materials for the production of pots

Abstract

Use of a composite for the production of a nursery pot. The composite comprises polyolefin in concentration by weight between 75 and 90%; cellulose fibre in concentration by weight less than 5%; aluminium or copper in concentration by weight less than or equal to 13%; PET in concentration by weight less than 3%; water and any impurities, collectively, in concentration by weight less than 2%.

Description

[0001] “USE OF COMPOSITE MATERIAL DERIVED FROM RECYCLING POLYLAMINATE MATERIALS FOR THE PRODUCTION OF POTS” DESCRIPTION

[0002] FIELD OF INVENTION

[0003] The invention relates to the use of a composite material derived from recycling operations of polylaminate materials for the production of nursery pots, i.e. pots for floriculture and / or horticulture.

[0004] STATE OF THE ART

[0005] Nursery pots for floriculture and / or horticulture are used by amateur and professional growers to start plants and nurture them to various stages of growth. The “growing success” is contingent upon both growing techniques and the growing environment of the plants. The growing environment can vary significantly depending on the characteristics of the soil used, but also on the type of container in which the plants’ seeds are placed.

[0006] Numerous types of containers and media have been developed for growing nursery stock. In order to successfully grow nursery stocks, growers need to choose a suitable nursery pot by taking into account their shape, size and material. It is known that the floriculture / horticulture sector is constantly searching for new materials that can exhibit advantageous properties for the cultivation and growth of plants, such as, for example, air permeability, water permeation, as well as temperature control, while also possessing the necessary mechanical properties to allow for their industrial production, storage, handling and transportation, even in the final use by users, such as greenhouses and nurseries.

[0007] These materials should also ideally be recyclable or compostable to have a low environmental impact, considering the widespread global use of these products, in order to allow for their reuse at the end of their life cycle.

[0008] The materials currently available on the market fail to simultaneously meet said plurality of these needs.

[0009] For example, a commonly used material is terracotta, a material that is highly resistant to both heat and frost, does not show cracks due to thermal shock, but is very fragile and difficult to handle due to its very high weight; this material has high porosity, which facilitates the breathing of both soil and plant roots, while also, though, allowing rapid evaporation of water, especially in summer, making it less than ideal for maintaining the necessary soil moisture conditions.

[0010] Another widely used material is wood, which is an excellent material in terms of porosity, considering that air and water circulate easily and in a more controlled manner among the fibres and cracks of the slats, and the fact that the soil contained therewith never overheats excessively in the sun, allowing to maintain freshness and humidity even in the hottest months. The disadvantage of these pots is certainly their cost and poor mechanical performance; they deteriorate very quickly, so their lifespan is rather short.

[0011] Yet another commonly used material is metal; this material is easily decorable and is also very strong and durable; however, it does not allow optimal breathing of the soil and plants and tends to retain heat, overheating.

[0012] However, one of the main and most widespread materials used for making pots is certainly polyethylene, given that it has a low cost, adequate strength resulting in considerable durability, as well as appreciated lightweight, making it easy to handle. Additionally, in summer, it retains soil moisture well, due to the impermeability of its walls.

[0013] In recent years, there has been a growing use, for example, of recycled polyethylene, often mixed with virgin polyethylene, to obtain a more environmentally friendly material, still easily workable and with the necessary mechanical properties.

[0014] However, polyethylene is a material that does not offer particular advantages in terms of plant cultivation, and pots made of this material, for example, do not allow good air circulation and suffer from the problem of not providing any barrier or control against temperature fluctuations, with evident negative effects on the health of plants, especially their roots. In winter months, in fact, frost can penetrate through the walls into the soil, therefore propagating to the plant roots, while in summer months, the temperature inside the pots can reach very high values due to direct exposure to sunlight, resulting in undesired overheating of both soil and roots.

[0015] Finally, another material widely used for making pots is polypropylene, which, however, suffers from the same issues as polyethylene regarding the lack of control over temperature fluctuations, with evident negative effects on the health of plants, especially their roots, which experience significant overheating in summer.

[0016] The issue of summer overheating of pots, and therefore of soil and plants, is, among other things, a rather sensitive issue in floriculture.

[0017] To avoid this overheating, specific solutions have also been proposed, such as those described in the Italian patent IT102014902292618, which involves the use of an additional device made of thermally insulating and reflective material, with which to cover pots made with traditional materials.

[0018] It is evident, therefore, that the materials currently available do not meet the multiple needs of end-users.

[0019] There is still a need to find new materials to be used in the sector that may confer additional properties and advantages for the cultivation of plants.

[0020] The primary object of the present invention is, therefore, to identify a new material to be used for making pots that is, at the same time, easily workable on an industrial level, has the necessary mechanical properties for its ordinary use, provides advantages in plant cultivation, avoids, in particular, soil and root overheating, and has a low environmental impact.

[0021] SUMMARY OF THE INVENTION

[0022] The above-described object has been achieved by using a composite material preferably derived from recycling operations of poly lam inate materials for the production of nursery pots, i.e. pots for floriculture / horticulture.

[0023] In particular, and surprisingly, the inventors have found that a raw material, preferably derived from recycling operations of polylaminate materials mainly comprising polyolefin, could be used successfully for the production of nursery pots.

[0024] In one aspect, the invention, thus, relates to the use of a composite for the production of a nursery pot, said composite comprising:

[0025] • polyolefin in concentration by weight between 75 and 90%;

[0026] • cellulose fibre in concentration by weight less than 5%;

[0027] • metal in concentration by weight less than or equal to 13%;

[0028] • polyethylene terephthalate (PET) in concentration by weight less than 3%; • water and any impurities, collectively, in concentration by weight less than 2%; wherein the metal is aluminium or copper.

[0029] In one embodiment, the invention relates to the use of a composite for the production of a nursery pot, said composite comprising:

[0030] • polyolefin in concentration by weight between 75 and 90%;

[0031] • cellulose fibre in concentration by weight between 1 and 4.5%;

[0032] • aluminium or copper in concentration by weight between 7 and 13%;

[0033] • PET in concentration by weight between 0.1 and 2.8%;

[0034] • water and any impurities, collectively, in concentration by weight less than 2%.

[0035] In another embodiment, the invention relates to the use of a composite for the production of a nursery pot, said composite comprising:

[0036] • polyolefin in concentration by weight between 83 and 88%;

[0037] • cellulose fibre in concentration by weight between 1 .5 and 2.5%;

[0038] • aluminium or copper in a concentration by weight between 8 and 11 %;

[0039] • polyethylene terephthalate (PET) in concentration by weight between 1.5 and 2%;

[0040] • water and any impurities, collectively, in concentration by weight less than 2%.

[0041] In yet another aspect, the invention relates to the use of a mixture of the composite according to the invention and another polymer, preferably a polyolefin, for the production of a nursery pot.

[0042] In one embodiment, said mixture comprises:

[0043] • polyolefin in concentration by weight between 75 and 90%;

[0044] • cellulose fibre in concentration by weight less than 5%;

[0045] • aluminium or copper in concentration by weight less than or equal to 13%;

[0046] • PET in concentration by weight less than 3%;

[0047] • water and any impurities, collectively, in concentration by weight less than 2%; and another polymer, preferably a polyolefin.

[0048] In another embodiment, said mixture comprises: • polyolefin in concentration by weight between 75 and 90%;

[0049] • cellulose fibre in concentration by weight between 1 and 4.5%;

[0050] • aluminium or copper in concentration by weight between 7 and 13%;

[0051] • PET in concentration by weight between 0.1 and 2.8%;

[0052] • water and any impurities, collectively, in concentration by weight less than 2%; and another polymer, preferably a polyolefin.

[0053] In yet another embodiment, said mixture comprises:

[0054] • polyolefin in concentration by weight between 83 and 88%;

[0055] • cellulose fibre in concentration by weight between 1 .5 and 2.5%;

[0056] • aluminium or copper in concentration by weight between 8 and 11 %;

[0057] • polyethylene terephthalate (PET) in concentration by weight between 1.5 and 2%;

[0058] • water and any impurities, collectively, in concentration by weight less than 2%. and another polymer, preferably a polyolefin.

[0059] Preferably, said other polymer is high-density polyethylene, low-density polyethylene, or mixtures of low-density and high-density polyethylene, and even more preferably, said polyethylene is recycled polyethylene.

[0060] In yet another preferred embodiment, said mixture comprises:

[0061] • polyolefin in concentration by weight between 85 and 86% and said polyolefin is a mixture of HDPE, LDPE and PP;

[0062] • cellulose fibre in concentration by weight of about 2.2%;

[0063] • aluminium in concentration by weight of about 9.7%;

[0064] • polyethylene terephthalate (PET) in concentration by weight of about 0.9%;

[0065] • water and any impurities, collectively, in concentration of about 1.1 %.

[0066] In another aspect, the invention also relates to a pot obtainable from the composite or the mixture according to the uses of the invention.

[0067] In fact, the inventors surprisingly found that pots made with the composite or the mixture having the above-described composition exhibited optimal control over temperature fluctuations, resulting in plants being better protected also from the consequences of their exposure to variable external temperatures.

[0068] Furthermore, the inventors surprisingly found that the composite or the mixture according to the invention, despite the presence of appreciable amounts of aluminium in the material, could be used in the production of pots intended for the cultivation and growth of plants without them showing any suffering during their growth, indeed even resulting in them being more vigorous, as will be clearer from the examples in the experimental part that follows.

[0069] FIGURES

[0070] Fig. 1 is a graph showing the trend of aluminium release from a VASinv pot made with the composite according to the invention, after 1 , 7, and 30 days of extraction with a 0.5% citric acid solution, having a pH of 2.5 (line with values represented by circles), or with distilled water having a pH of 7.5 (line with values represented by squares). On the y-axis, the values of aluminium micrograms detected in the solution are reported, expressed with respect to the weight unit of the pot (pg of Al / g of pot).

[0071] Fig. 2 is a graph showing the trend of aluminium transfer from a pot made with recycled polyethylene material from two different batches (pot VASpel and pot VASpe2), after 1 , 7, and 30 days of extraction with a 0.5% citric acid solution, having a pH of 2.5. On the y-axis, the values of aluminium micrograms detected in the solution are reported, expressed with respect to the weight unit of the pot (pg of Al / g of pot).

[0072] Fig. 3 is a graph showing the trend of the average concentration of aluminium in the drained liquid of bean plants grown in VASinv and VASpe pots. The error bars represent the standard deviation of the measurement (n=3). For each data point, the average pH value of the drained liquid is also provided. The graph also indicates the maximum limit of recommended aluminium in aqueous extracts of substrates, equal to 215.84 pg Al / L according to the International Substrate Manual, published by Elsevier.

[0073] DETAILED DESCRIPTION OF THE INVENTION

[0074] The invention therefore relates to the use of a composite for the production of a nursey pot, said composite comprising: • polyolefin in concentration by weight between 75 and 90%;

[0075] • cellulose fibres in concentration by weight less than 5%;

[0076] • metal in concentration by weight less than or equal to 13%;

[0077] • PET in concentration by weight less than 3%;

[0078] • water and any impurities, collectively, in concentration by weight less than 2% wherein the metal is aluminium or copper.

[0079] In the present invention, when using the term:

[0080] • “pot” it is meant more generally any container used preferably in the floriculture / horticulture sector and intended to house seeds or plants, such as, for example, pots and seed trays, and therefore to come into contact with the soil in which they are planted.

[0081] • “impurities” it is meant additional materials not expressly defined and present along with water in the composite according to the invention in quantities less than or equal to 2%.

[0082] In one embodiment, the composite according to the present invention comprises:

[0083] • polyolefin in concentration by weight between 75 and 90%;

[0084] • cellulose fibres in concentration by weight between 1 and 4.5%;

[0085] • aluminium or copper in concentration by weight between 7 and 13%;

[0086] • PET in concentration by weight between 0.1 and 2.8%;

[0087] • water and any impurities, collectively, in concentration by weight less than 2%.

[0088] As known, the term polyolefin refers to a polymeric material obtained from the polymerization of olefins.

[0089] Said polyolefin is high-density polyethylene (HDPE), low-density polyethylene (LDPE), polypropylene, or mixtures thereof.

[0090] Said composite preferably derives from recovery / recycling processes of polylaminate materials, i.e. those materials commonly referred with the term tetrapak, generally used, for example, in the food industry for the production of various containers suitable for the storage of both fresh foods, therefore intended for refrigeration, and long-life foods.

[0091] Preferably, when said polymeric material derives from the recycling process of polylam inate materials, it consists of a polyolefin selected from the group comprising polypropylene, high-density polyethylene, low-density polyethylene, and mixtures thereof.

[0092] A particularly preferred composite is the commercial composite called Grandplast, produced and distributed by Lucart Spa, and better described in Example 1 of the following experimental part.

[0093] Thus, in yet another preferred embodiment, said composite comprises:

[0094] • polyolefin in concentration by weight between 85 and 86% and said polyolefin is a mixture of HDPE, LDPE and PP;

[0095] • cellulose fibre in concentration by weight of about 2.2%;

[0096] • aluminium in concentration by weight of about 9.7%;

[0097] • polyethylene terephthalate (PET) in concentration by weight of about 0.9%;

[0098] • water and any impurities, collectively, in concentration of about 1.1 %.

[0099] More preferably, said polyolefin comprises from 25 to 35% by weight of high- density polyethylene (HDPE) and from 60 to 70% by weight of low-density polyethylene (LDPE).

[0100] Even more preferably, said polyolefin comprises polypropylene in a maximum amount of 5% by weight, preferably about 3% by weight.

[0101] When the polyolefin is a mixture of HDPE, LDPE and PP, more preferably, it comprises HDPE in a concentration by weight between 26 and 27%, LDPE in a concentration by weight between 55 and 57% and PP in a concentration by weight between 2 and 3%.

[0102] Cellulose fibres are fibres made up of polysaccharides.

[0103] The metal is preferably aluminium.

[0104] PET is the polymer polyethylene terephthalate.

[0105] The composition may also include variable amounts of impurities, as well as water, typically in modest amounts.

[0106] In a particularly preferred embodiment, the invention relates to the use of a composite for the production of a nursery pot, the composite comprising:

[0107] - polyolefin in concentration by weight between 83 and 88%;

[0108] - cellulose fibre in concentration by weight between 1 .5 and 2.5%;

[0109] - aluminium or copper in concentration by weight between 8 and 11 %; - polyethylene terephthalate (PET) in concentration by weight between 1.5 and 2%;

[0110] - water and any impurities, collectively, in concentration by weight less than 2%.

[0111] The inventors of the present invention, therefore, surprisingly found that the composite according to the invention allowed optimal control of temperature fluctuations, resulting in plants being better protected even from the consequences of their exposure to variable external temperatures.

[0112] In particular, the composite according to the invention exhibited a mitigating effect on the rise in internal temperature of the pots subjected to strong heat sources, as happens, for example, during the summer months of intense exposure to sunlight, thus managing to mitigate the microclimate of the plant growth environment, making it more tolerable.

[0113] Therefore, in a preferred aspect of the invention, the pot made with the composite of the invention is preferably used to grow plants intended to be placed in outdoor environments, under direct exposure to climatic agents.

[0114] Furthermore, the inventors of the present invention surprisingly found that said composite could be used successfully in the production of pots intended for the cultivation and growth of plants without these showing any suffering during their growth, despite the presence of considerable concentrations of aluminium in the material, a notoriously phytotoxic element, indeed appearing even more vigorous than plants cultivated in pots made of traditional materials, commonly used, as will be evident from the following description.

[0115] Without being bound by any theory, the inventors hypothesized that the particular composite according to the invention, which is made of many polymeric matrices, would generate a sort of controlled release effect on the metal contained therein, letting small concentrations of it to be made available, which would favour plant stimulation rather than causing damage to them. As will be evident from the experimental part that follows, plants grown in pots made with the material according to the invention were indeed even more developed and healthier than plants grown in traditional pots characterized by very low metal release values, especially aluminium. The experiments conducted also demonstrated that this unexpected phytostimulant effect on plants was greater when the pH of the soil was particularly acidic.

[0116] Therefore, in a further preferred aspect of the invention, the pot made with the composite of the invention is preferably used to grow plants in acidic soils with a pH below 5.5, preferably below 4, even more preferably below 3.5.

[0117] Significant results were obtained in particular on bean plants, plants notoriously very sensitive to the presence of aluminium in soils, as will be evident from the experimental part that follows.

[0118] The pots made with the composite according to the invention are also pots with exceptionally low environmental impact, since the material they are made of is preferably derived from the recycling of polylaminate materials.

[0119] In yet another aspect, the invention relates to the use of a mixture of the composite according to the invention and another polymer, preferably a polyolefin for the production of a nursery pot.

[0120] In one embodiment, said mixture comprises:

[0121] - polyolefins in concentration by weight between 75 and 90%;

[0122] - cellulose fibre in concentration by weight less than 5%;

[0123] - aluminium or copper in concentration by weight ess than or equal to 13%;

[0124] - PET in concentration by weight ess than 3%;

[0125] - Water and any impurities, collectively, in concentration by weight less than 2%; and another polymer, preferably a polyolefin.

[0126] In another embodiment, said mixture comprises:

[0127] • polyolefin in concentration by weight between 75 and 90%;

[0128] • cellulose fibre in concentration by weight between 1 and 4.5%;

[0129] • aluminium or copper in concentration by weight between 7 and 13%;

[0130] • PET in concentration by weight between 0.1 and 2.8%;

[0131] • water and any impurities, collectively, in concentration by weight less than 2%; and another polymer, preferably a polyolefin.

[0132] In yet another embodiment, said mixture comprises: • polyolefin in concentration by weight between 83 and 88%;

[0133] • cellulose fibre in concentration by weight between 1 .5 and 2.5%;

[0134] • aluminium or copper in concentration by weight between 8 and 11 %;

[0135] • polyethylene terephthalate (PET) in concentration by weight between 1.5 and 2%;

[0136] • water and any impurities, collectively, in concentration by weight less than 2%. and another polymer, preferably a polyolefin.

[0137] Preferably, said other polymer is high-density polyethylene, low-density polyethylene, or mixtures of low and high-density polyethylene, and even more preferably, said polyethylene is recycled polyethylene.

[0138] The use of the composite according to the invention in combination with said other polymer in the mixture confers several advantages.

[0139] One of the main advantages of using such combination is the resulting workability of the material. In fact, the composite according to the present invention helps to reshape the mechanical properties of the copolymer, making it more ductile and elastic, thus more easily workable.

[0140] In a particularly advantageous aspect of the invention, said other polymer, preferably low-density polyethylene LDPE, even more preferably recycled low- density polyethylene LDPE, is present in the final mixture at a concentration ranging from 20 to 50% by weight.

[0141] Preferably, said metal is copper or aluminium, more preferably aluminium.

[0142] Finally, in a further aspect, the invention relates to a pot that can be obtained from the composite or the mixture according to the uses of the invention.

[0143] The advantageous properties of the use according to the invention are also supported by the experimental part that follows.

[0144] EXPERIMENTAL PART

[0145] Example 1 - Preparation of pots using the composite according to the invention.

[0146] For the preparation of the pots, a composite derived from recovery and recycling operations of aluminium polyamminate materials was used, in particular the commercial composite called Grandplast, produced and marketed by Lucart SpA, having the following composition (where each value is affected by a determination error which can reach up to 5%):

[0147] • polyolefin in concentration by weight overall equal to approximately 85.4%, comprising: o HDPE in concentration by weight approximately equal to 26.8%; o LDPE in concentration by weight approximately equal to 56.0%; o PP in concentration by weight approximately equal to 2.6%;

[0148] • cellulose fibre in concentration by weight approximately equal to 2.2%;

[0149] • aluminium in concentration by weight approximately equal to 9.7%;

[0150] • PET in concentration by weight approximately equal to 0.9%;

[0151] • water in concentration by weight approximately equal to 0.3%;

[0152] • other low molecular weight impurities in concentration by weight approximately equal to 0.8%;

[0153] Pots, each having a diameter of 15 cm, height of 14 cm, and weight of approximately 180 grams, were made using this composite.

[0154] These pots made with the composite according to the invention, hereinafter referred to as VASinv, were used to carry out the tests detailed below.

[0155] Example 2 - Heating tests

[0156] Some pots prepared according to Example 1 (VASinv) and some commercial pots made of recycled polyethylene (VASpe), of identical dimensions, filled with blonde peat, were subjected to heating tests by exposing them to direct sunlight for a period of 5 consecutive days falling within the first week of July.

[0157] The heating experienced by the pots was determined by placing a temperature meter (FT-BT05 Bluetooth Econorma, Treviso) in close contact with the inner wall of the pot facing south and acquiring temperature data at different times of the day. During the central and hottest hours of the day (from 1 :00 pm to 3:00 pm), the recycled polyethylene pot VASpe consistently showed higher average temperatures than those reached by the pot according to the invention VASinv, with peaks of about 10°C, as evident in the following table 1 :

[0158] Table 1 - Temperature values measured near the inner wall of the pots in the 3-5 pm time slot on 5 consecutive days.

[0159] The surprising outcome of these tests, also considering the presence of aluminium in the VASinv pots, an excellent heat conductor, demonstrated the possibility of using the composite according to the invention for the production of nursery pots exhibiting, in addition to the necessary mechanical properties, also excellent thermal properties, which allowed to reduce the overheating, during summer, of the soil contained in them, thus also reducing the overheating of the roots and, in general, of the plant, and thereby decreasing significantly the amount of stress normally experienced by the same .

[0160] Therefore, the composite according to the invention allowed to produce pots significantly more suitable for the plant's growth needs and general health compared to widespread polyethylene pots already on the market.

[0161] Example 3 - Aluminium release tests in the laboratory.

[0162] Given the excellent performance of the pots made according to the invention, a test was carried out to verify, given the presence of aluminium in the composite, that the pot did not release significant amounts of aluminium into the soil that could harm the health of the plants, thus rendering null the beneficial effects obtainable from a thermal perspective.

[0163] Therefore, release tests were conducted, first in the laboratory, then in the field. The release tests conducted in the laboratory aimed to ascertain whether or not the pot according to the invention, VASinv, in contact with the water present in the soil, would release significant amounts of aluminium.

[0164] Extraction tests were therefore conducted using a simulation fluid consisting of an aqueous solution of 0.5% by weight of citric acid, having a pH of 2.5.

[0165] A particularly acidic extracting environment was chosen to simulate the pH of the soils used in plant cultivation, as, for example, peat, one of the most commonly used, has a pH that can vary from 5.5 to a value even lower than 3. The test was then replicated on commercial pots made from recycled polyethylene from two different batches (VASpel and VASpe2) already used in example 2. Materials and methods.

[0166] Pots from example 1 (VASinv) were cut and reduced into small pieces of approximately 4 cm2.

[0167] After standardizing the sample, about 50 grams of these fragments were placed in a Pyrex® glass bottle with a screw cap containing 400 ml of an extraction solution of 0.5% by weight of citric acid or only osmotized water.

[0168] Each sample was placed on an orbital shaker and heated to 50°C for 1 hour, stirred for 8 hours, and then stored in the dark at room temperature.

[0169] The extraction, under the two different conditions, was repeated three times on three different samples taken from different pots.

[0170] Subsequently, samples of the solution in contact with the sample were taken, respectively, after 1 day, after 1 week (7 days), and after 1 month (30 days) from the start of the extraction, by taking a portion of 40 ml from the starting volume after placing the sample on an orbital shaker for 4 hours.

[0171] The concentration measurement of the extracted sample was performed using Inductively Coupled Plasma (ICP) instrumentation coupled with mass spectrometry (ICP-MS). All measured data were corrected by subtracting the value of aluminium concentration present in the extracting solution (blank) from the sample reading and were expressed as micrograms of aluminium released per gram of unit weight of the pot.

[0172] Results.

[0173] As shown in Fig. 1 , the pot according to the invention, VASinv, released significant amounts of aluminium, and this release occurred in significantly different amounts depending on the pH of the extraction medium.

[0174] Indeed, deionized water, having a pH between 7.5 and 7.8, showed a low value (mean value ± standard deviation) of aluminium released, and this value was practically not statistically different between the three sampling periods (1 , 7, or 30 days) and amounted to 1 .1 ± 0.19 pg of Al / g of pot weight.

[0175] Extraction with citric acid, occurring at a pH of about 2.5, instead, greatly increased the value of aluminium released from the pot to the extracting solution, increasing with the extraction period ranging from a minimum value of 0.6 ± 0.1 , to 10.2 ± 1 .4, and to 135.8 ± 3.1 pg of Al / g of pot weight respectively after 1 , 7, or 30 days from the start of extraction.

[0176] The test conducted on commercial pots made of recycled polyethylene (VASpel and VASpe2), as shown in Fig. 2, confirmed that even the pot with recycled polyethylene released increasing amounts of aluminium over time in the presence of a strongly acidic solution, varying also with the batch of recycled material used (the high variability in aluminium release observed in recycled polyethylene material was attributed to the variability in the composition of the plastic collection material). However, the final value of aluminium release after 30 days of extraction ranged from a minimum of 4.1 ± 0.6 to 11.3 ± 2.0 pg of Al / g of pot weight, therefore the aluminium release from the pot according to the invention, VASinv, was 12 to 32 times higher than that observed on traditional pots made of recycled polyethylene, VASpel and VASpe2.

[0177] Considering that the laboratory test had shown a significant release of aluminium from the pot according to the invention, VASinv, it was deemed appropriate to carry out further tests to verify that these aluminium concentrations did not induce acute or chronic phytotoxicity during plant cultivation.

[0178] Example 4 - Cultivation tests of bean plants.

[0179] For these cultivation tests, bean plants were used, a species known to be particularly sensitive to aluminium phytotoxicity, in order to better highlight any effects due to the release of this element from the pot according to the invention (VASinv). Comparison tests were carried out with commercial pots made of recycled polyethylene (VASpe).

[0180] A cultivation test of bean plants was then carried out at the experimental greenhouse of DiSAAA-a with the aim of highlighting any cases of phytotoxicity and quantifying the accumulation of aluminium in the various organs of the plant and verifying whether this could be compatible with the maximum tolerable weekly intake (TWI) recommended by EFSA (1 mg / kg b.w. per week).

[0181] Materials and Methods.

[0182] The test was conducted in a heated iron and glass greenhouse (coordinates: lat. 43.704033, long.: 10.427475), using VASinv and VASpe pots with a diameter of 15 cm. Twelve pots were prepared for each type, filled with non-neutralized blonde peat (Lithuanium Peat) to create a root environment as acidic as possible (substrate pH, determined with 1 :2 V / V aqueous extract, equal to 3.3), with the aim of promoting as much as possible the release of aluminium ions from the pot walls. 5 seeds of borlotti bean (Phaseolus vulgaris L.) nano cv "Lingua di fuoco" (Gargini Sementi, Lucca) per pot were then sown. After seed germination, thinning was performed to leave only 4 plants per pot, resulting in a crop density of 28 plants / m2During the first 25 days after sowing, manual irrigation was carried out to avoid excessive drainage from the pots and to maintain as much as possible the acidity and the released aluminium ions inside the substrate, subsequently, following the increase in the evapotranspiration of the crop, an irrigation system with capillary tubing was installed, which allowed for the plants to be irrigated automatically. The average leaching percentage during the first 25 days was approximately 3-5%, while after the installation of the irrigation system, it was 35%. During cultivation, four fertigations with a "Hoagland Universale" type nutrient solution were carried out. During the cultivation, on days 13, 43, and 83 after sowing, leachates were collected from the pots to determine the aluminium content using the ICP-MS technique. The Al content in the irrigation water was below the instrument's detection limit (<37 micrograms / L). After 25 days from the germination (10 / 05 / 2023) and at the moment of seed maturation, a growth analysis was conducted by quantifying the fresh and dry matter in various organs (roots, stems, leaves, pods, and seeds) of four pots for each of the two types of pots on comparison. The dry weight of the various organs was determined after being dried in a ventilated oven at 70°C until reaching a constant weight. Subsequently, the dry matter was ground with a suitable mill, and aluminium in the dry matter of various organs was determined before and after perchloric-nitric digestion using ICP-MS.

[0183] Results.

[0184] The concentration of aluminium in the leachates collected from the pots at 13, 43, and 83 days after sowing clearly showed a significant release of aluminium ions from the VASinv pot, which, as evident in Fig. 3, reached up to values 12 times higher than the maximum recommended value (215.84 pg of Al / L) by the International Substrate Manual. The concentration of aluminium determined in the leachate from VASinv was approximately twice that found in the leachate obtained from VASpe pots, and even the latter was well above the maximum recommended limit. Subsequently, with the increase in pot leaching following the installation of the irrigation system, the concentration of aluminium ions in the leachate naturally decreased, and after 43 days from germination, it was 201 and 83 pg of Al / L for VASinv and VASpe, respectively, dropping below the instrument's detection limit in the last measurement taken after 83 days. The progressive reduction of aluminium ions in the pot leachate was attributed to the increased leaching from the pots starting from day 25 after sowing and the progressive increase in the pH of the substrate due to the replacement of H+ions with Ca2+and Mg2+ions and the sequestration of H+ions by bicarbonates (HCOs-) present in the irrigation water. Despite this significant release of aluminium, and surprisingly, the growth analysis conducted after 43 days from sowing did not show any symptoms of aluminium phytotoxicity in the plants of the two compared treatments and it highlighted, instead, a significantly greater growth of bean plants cultivated in VASinv compared to those cultivated in VASpe, with an increase in the total dry weight of the aboveground part by approximately 30%, as evident from the data reported in table 2. The mean and standard deviation values, with n=4, refer to the biomass of a whole pot containing 4 bean plants; Table 2 also shows the index value of the parameter observed in the VASinv pot compared to that observed in VASpe, set equal to 100. For each parameter, different letters correspond to a significant difference between the means, according to the Least Significant Difference test (P< 5%).

[0185] Tab. 2. Growth analysis of bean plants 43 days after sowing grown in VASinv or VASpe.

[0186] This effect naturally tended to flatten over time; for example, after 83 days, once almost all the aluminium had been leached out and almost comparable growth conditions had been obtained for the two pots.

[0187] The results obtained thus highlighted that the VASinv pot according to the invention had induced a stimulating effect on plant growth, probably due to the fact that the initially very low pH value of the substrate (pH 3.3 of the aqueous extract 1 :1 V:V), had promoted the greater release of aluminium ions from the pot, which exerted a protective action against the negative effects of acidity and allowed an increase in plant growth compared to the control pot VASpe.

[0188] Evidently, this positive effect of aluminium on the pH surprisingly prevailed over its potential phytotoxicity, creating a more favourable environment for plant development, with a clearly evident phytostimulation effect.

[0189] The VASinv pot could therefore be safely used for the cultivation of any other plant, considering that no phytotoxic effects were observed on the tested bean plants, plants notoriously more sensitive than others to the presence of aluminium.

[0190] Example 5. Cultivation trials of lettuce, blueberry, and raspberry.

[0191] The inventors finally tested the VASinv and VASpe pots also in the cultivation of lettuce, blueberry, and raspberry, using the same methodology and procedure as described in Example 3.

[0192] The results are evident from the data reported in the following tab. 3, 4, and 5, which show growth increases of up to about 70% for plants cultivated in VASinv compared to those cultivated in VASpe.

[0193] The tables show the index value of the parameter observed in the VASinv compared to that observed in the VASpe made equal to 100. For each parameter, a different letter corresponds to a significant difference between the means, according to the Least Significant Difference test (P < 5%).

[0194] Tab.3. Growth analysis of LETTUCE plants grown in VASinv or VASpe. The mean and standard deviation data, with n=6, refer to the biomass of an entire pot.

[0195] Tab.4. Growth analysis of BLUEBERRY plants grown in VASinv or VASpe. The mean and standard deviation data, with n=5, refer to the biomass of an entire pot.

[0196] Tab.5. Growth analysis of RASPBERRY plants grown in VASinv or VASpe. The mean and standard deviation data, with n=5, refer to the biomass of an entire pot.

[0197] This test demonstrated the enormous versatility of the pots according to the invention, which could be used with surprisingly significant results for any plant. Example 6. Production of pots with mixtures of composite and polyolefin. To improve the workability of the pots during production and their resistance to use during deployment, the inventors also made some pots using a mixture of composite and polyolefin.

[0198] In particular, pots consisting of a mixture comprising: - 70% of the composite from Example 1 ;

[0199] - 30% of low-density recycled polyethylene LDPE.

[0200] The pots thus obtained proved to be perfectly workable and suitable for the purpose.

Claims

CLAIMS1. Use of a composite for the production of a nursery pot, said composite comprising:- polyolefin in concentration by weight between 75 and 90%;- cellulose fibre in concentration by weight less than 5%;- metal in concentration by weight less than or equal to 13%;- PET in concentration by weight less than 3%;- water and any impurities, collectively, in concentration by weight less than 2%; wherein the metal is aluminium or copper.

2. The use of the composite according to claim 1 wherein said composite comprises:- polyolefin in concentration by weight between 83 and 88%;- cellulose fibre in concentration by weight between 1 .5 and 2.5%;- aluminium or copper in concentration by weight between 8 and 11 %;- PET in concentration by weight between 1 .5 and 2%;- water and any impurities, collectively, in concentration by weight less than 2%;3. The use of the composite according to claim 1 or 2, wherein said composite is a composite derived from the recycling of polyamminate materials, preferably the commercial composite called Grandplast.

4. The use of the composite according to any one of claims 1 to 3, wherein said polyolefin is high-density polyethylene (HDPE), low-density polyethylene (LDPE), polypropylene, or mixtures thereof.

5. The use of the composite according to claim 4, wherein said polyolefin comprises from 25 to 35% by weight of high-density polyethylene (HDPE) and from 60 to 70% by weight of low-density polyethylene (LDPE).

6. The use of the composite according to claim 4 or 5, wherein said polyolefin comprises polypropylene in a maximum amount of 5% by weight, preferably comprises polypropylene in an amount of about 3% by weight.

7. The use of the composite according to any one of claims 1 to 6, wherein the metal is aluminium.

8. The use of the composite according to claim 4, wherein:- polyolefin is in concentration by weight between 85 and 86% and said polyolefin is a mixture of HDPE, LDPE and PP;- cellulose fibre is in concentration by weight of about 2.2%;- aluminium is in concentration by weight of about 9.7%;- polyethylene terephthalate (PET) is in concentration by weight of about 0.9%;- water and any impurities, collectively, are in concentration of about 1.1 %.

9. Use of a mixture comprising the composite according to any one of claims 1 to 8, and a polyolefin for the production of a nursery pot.

10. The use of the mixture according to claim 9, wherein said composite is present in an amount ranging from 50 to 80% by weight and the polyolefin is present in an amount ranging from 20 to 50% by weight.11 . The use of the mixture according to claim 9 or 10, wherein said polyolefin is high-density polyethylene (HDPE), low-density polyethylene (LDPE), polypropylene, or mixtures thereof, preferably is low or high-density polyethylene, even more preferably is low or high-density polyethylene derived from recycling.

12. A pot obtainable from the composite of claims 1 to 8 or from the mixture of claims 9 to 11 .

13. The use of a pot according to claim 12 for cultivating plants intended to be placed in outdoor environments, under direct exposure to climatic elements.

14. The use of a pot according to claim 12 or 13 for cultivating plants in acidic soils with a pH lower than 5.5, preferably lower than 4, even more preferably lower than 3.5.

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