WO2020144267A1

WO2020144267A1 - Absorbent sachet, packaging

Info

Publication number: WO2020144267A1
Application number: PCT/EP2020/050410
Authority: WO
Inventors: Pablo Julián MÚGICA ELORZA; Íñigo ALONSO ECHEVARRÍA
Original assignee: Ozeano Urdina S.L.
Priority date: 2019-01-09
Filing date: 2020-01-09
Publication date: 2020-07-16
Also published as: ES2773332B2; ES2773332A1

Abstract

A gas-absorption sachet(1) comprising a receptacle (2) housing a filtering granulate (3) in its interior for absorbing gases. The receptacle (2) is made up of a sheet that provides rigidity, said sheet being made of a gas- permeable material, joined to or integrated with a plastic material impermeable to water and permeable to harmful gases. The weight of the plastic material is less than or equal to 20 g/m². The sheet that provides rigidity, made of a gas- permeable material, is a cellulose sheet or non-woven fabric sheet. The plastic material is chosen from the following plastic materials: ethylene-vinyl-acetate (EVA), ultra low-density polyethylene, low-density polyethylene, medium-density polyethylene, high-density polyethylene, low-density linear polyethylene, polypropylene, polybutylene, ionomers, polystyrene (PS) and mixtures thereof. Packaging for packing perishable products comprising a sachet such as the one described above.

Description

ABSORBENT SACHET, PACKAGING

DESCRIPTION

FIELD OF THE INVENTION

The present invention belongs to the field of preservation of perishable products, such as vegetable or animal products. More specifically, the invention relates to a device that absorbs ethylene and other harmful gases, such as ethanol, acetaldehyde, hydrogen sulfide, inter alia, produced by vegetable products or other perishable products. The device of the invention is designed to be placed in or attached to containers or packaging that house perishable products during the transport, distribution and/or marketing thereof, to absorb the emissions of said products, that induce the maturation and deterioration thereof. BACKGROUND OF THE INVENTION

When a perishable product, such as fruit, vegetables, flowers, etc., is packaged in a packaging, such as boxes, bags, etc., a more or less confined atmosphere is created wherein various gases, typically emitted by the products that are packaged or produced as a result of the emissions from said products, induce maturation, deterioration, decay and fungal growth in the packaged products. Examples of these gases that induce maturation, deterioration, decay and fungal growth are ethylene, ethanol, acetaldehyde, inter alia.

In order to prevent or slow the deterioration, maturation, etc., of these perishable products, during packaging thereof in different packaging, such as boxes, bags, etc., various measures are usually adopted. On the one hand, filters to absorb harmful gases are used. These filters are usually placed in the interior of confined spaces, often refrigerated, wherein the perishable products are transported. And on the other, sachets that absorb the harmful gases are used, which are inserted in the packaging (bags, boxes, etc.) wherein the products have been packaged. For example, bags manufactured from Tyvek® (synthetic polyethylene fiber material) are normally used, filled with silicon gel, used to palliate the effects of the ambient humidity, or filled with clays or aluminas impregnated with permanganate to absorb ethylene. Although the Tyvek® used by bags of this type is impermeable to water in liquid state and permeable to harmful gases, this material is also permeable to water vapor, as claimed by the manufacturer of the product on http://www.dupont.com/products- and-services/construction-materials/building-pocket- systems/articles/understanding-vapor-permeability.html), last accessed 7 January 2019. This gives rise to a double problem: On the one hand, when the filling (typically clays or aluminas impregnated with permanganate) becomes saturated with water when condensations appear, it loses its effectiveness. For this reason, the manufacturers of these sachets are obliged to overdose the filling (for example, salts impregnated with permanganate), with the ensuing waste of resources and potential increase of hazardous discharges. On the other hand, condensed water, mixed with permanganate, migrates away from the Tyvek® sachet over time, giving rise to a serious food safety risk if the permanganate comes into contact with the product, such as fruit.

International patent application WO2015110682A1 discloses a sachet for absorbing gases that accelerate the maturation and deterioration of vegetable products, for application in boxes and bags for packaging said products. The sachet disclosed in this document is made up of a support sheet made of plastic material, such as low-density polyethylene (LDPE), water-impermeable, and of a resistant sheet, superimposed on the previous sheet, made of permeable material, such as cellulose, that provides strength. The thickness of plastic sheet of sachets such as that described in WO2015110682A1 and currently on the market is approximately 35 microns. A filtering granulate is housed in the interior of the sachet.

In view of the known proposals, it is desirable to optimize the effectiveness of the sachets so as to optimize their permeability to harmful gases and water-impermeability, while reducing the amount of materials used in the manufacture thereof, especially plastics and/or active or filtering material.

DESCRIPTION OF THE INVENTION

The present disclosure provides a gas absorption sachet, intended to be placed in containers -such as bags, boxes or packaging- of perishable products, such as vegetables, to eliminate gases, such as ethylene, which accelerate the maturation and deterioration of packaged perishable products.

In a first aspect of the present disclosure, a gas-absorption sachet is provided, comprising a receptacle which houses a filtering material in its interior for absorbing gases. The receptacle is formed by a sheet that provides rigidity, which is made of a gas-permeable material and joined to or integrated with a plastic material impermeable to water and permeable to harmful or unwanted gases. Non-limiting examples of harmful or unwanted gases to which said plastic material is permeable include: ethylene, ethanol, acetaldehyde and hydrogen sulfide. The weight (grammage) of the plastic material is less than or equal to 20 g/m² In the context of the present invention, the term "impermeable" is used, applied to water in any of its states, to indicate that there is no observable migration of water molecules through the walls of the receptacle that forms the sachet of the invention, over prolonged periods of time, i.e. of approximately between one and three months.

In embodiments of the invention, the sheet that provides rigidity, made of a material permeable to harmful gases, is a cellulose sheet or non-woven fabric sheet or of another gas-permeable material.

In embodiments of the invention, the plastic material that is impermeable to water and permeable to harmful gases is chosen from the following plastic materials: ethylene-vinyl-acetate (EVA), ultra low-density polyethylene, low- density polyethylene, medium-density polyethylene, high-density polyethylene, low-density linear polyethylene, polypropylene, polybutylene, ionomers, polystyrene (PS) and mixtures thereof.

In embodiments of the invention, the plastic material has been joined to the sheet that provides rigidity by extrusion, coextrusion, heat, molten plastic coating, spraying, pulverization or impregnation by spraying.

In embodiments of the invention, the weight of the plastic material is less than or equal to 20 g/m². such as less than or equal to 15 g/m², or between 5 and 12 g/m², or between 6 and 12 g/m², or between 6 and 1 1 g/m², or between 7 and 11 g/m², or between 7 and 10 g/m², or between 8 and 10 g/m².

In embodiments of the invention, the thickness of the plastic material is less than 25 pm, such as between 5 and 25 pm, or between 5 and 20 pm, or between 5 and 15 pm, or between 5 and 12 pm, or between 8 and 12 pm, or between 10 and 12 pm.

In embodiments of the invention, the sheet that provides rigidity, made of a gas-permeable material, has a weight ranging between 30 and 80 g/m², such as between 40 and 70 g/m² or between 40 and 60 g/m² or between 45 and 55 g/m².

In embodiments of the invention, no type of adhesive or any other material is used to join or integrate the sheet that provides rigidity and the plastic material.

In embodiments of the invention, an adhesive permeable to harmful gases is used to join or integrate the sheet that provides rigidity and the plastic material.

In embodiments of the invention, the filtering material comprises an impregnated porous substrate. The filtering material may be a granulate or powder.

In embodiments of the invention, the filtering material comprises a granulate formed by grains of a diameter ranging between 1 and 7 mm.

In embodiments of the invention, the plastic material remains in the interior of the receptacle, in contact with the filtering material, and the sheet that provides rigidity remains on the outside of the receptacle, in contact with the gases to be absorbed.

In another aspect of the present invention, a packaging (packing or package) is provided for packing perishable products comprising a sachet such as the one described in the first aspect above.

The advantages of the sachet of the invention namely include increased permeability to the gases to be eliminated, such as ethylene, without reducing the desired impermeability to water in any of its states (solid, liquid and gas). Additionally, the amount of plastic material used is reduced, with the ensuing environmental impact. Furthermore, reducing the amount of plastic used facilitates the integration of the plastic in the support sheet, to the point of avoiding the use of adhesives which, in addition to the evident advantage derived from a simplified and environmentally-friendly product, adds the advantage of facilitating the evaluation of gas permeability and water impermeability, upon eliminating the effect of the adhesives on said evaluation. Additionally, with respect to conventional sachets, such as those manufactured from Tyvek®, the sachet of the present invention is impermeable not only to water in the liquid state, but also to water vapor. Thus, a more efficient envelope is achieved from the viewpoint of the elimination of harmful gases and water saturation in the active material contained in the interior of the sachet pocket is prevented, which makes it possible to reduce the amount of active material without reducing its overall effectiveness. In other words, it was observed that permeability to water vapor, which is avoided in the pocket of the invention, reduces the effectiveness of absorption of unwanted gases, such as ethylene, due to the condensation of water in the interior of the packaging of perishable products and, therefore, to the presence of water in the interior of the sachet.

Additional advantages and features of the invention will be evident from the detailed description below and will be indicated in particular in the attached claims.

BRIEF DESCRIPTION OF THE FIGURES

To complement the description and for the purpose of helping to better understand the features of the invention, according to a practical exemplary embodiment thereof, a set of drawings is attached as an integral part of the description, wherein the following has been depicted, in an illustrative and non limiting manner:

Figure 1 shows a gas-absorption sachet in accordance with a possible embodiment of the invention. One of the ends of the sachet is open to show the filtering granulate material housed inside the sachet.

DESCRIPTION OF AN EMBODIMENT OF THE INVENTION

The following description should not be considered in a limiting sense, but rather is provided with the sole intention of describing broad principles of the invention. The following embodiments of the invention will be described by way of example, referring to the above-mentioned figures, which show devices and results in accordance with the invention.

The sachet of the present invention optimizes its permeability to harmful gases and impermeability to water in any of its states towards the interior of the sachet, reducing the amount of plastic used, ensuring that the sachet is much more environmentally friendly upon reducing the amount of plastic used in its manufacture. Additionally, by increasing its effectiveness, resulting from the optimized permeability to harmful gases and impermeability to water, it is possible to reduce the amount of active material in its interior.

Figure 1 shows a gas-absorption sachet or pocket 1 according to a possible embodiment of the invention. The sachet 1 is formed by a receptacle 2 housing a filtering material, product or composition 3 in its interior. The receptacle 2 is formed from two sheets, walls or flat surfaces, of the same size, made of the same material, joined or sealed along its edges, so as to configure a cavity or closed interior volume. That is to say, the receptacle is multilayered, specifically bilayered. In figure 1 , the shape of the sachet 1 , imposed by the shape of the receptacle 2, is square or rectangular. However, the sachet 1 may adopt any other shape, such as circular or oval, or any other. In figure 1 , one of the edges of the receptacle 2 is shown open so as to observe the filtering material 3 in its interior.

The receptacle 2 of the sachet 1 , i.e. the delimiting walls or surfaces of the sachet 1 , is made of a first sheet of a gas-permeable material, whereto a plastic material impermeable to water in any of its states (solid, liquid or gas), and permeable to harmful or unwanted gases, such as ethylene, ethanol, acetaldehyde and hydrogen sulfide, has been added, applied, joined or integrated. The first sheet provides rigidity to the assembly and, in order to allow the filtering material 3 to absorb the harmful gases, it must be permeable to these gases. The plastic material provides, inter alia, the functionality of impermeability to water, including water vapor. Therefore, the gases to be absorbed by the filtering material 3 are capable of entering the interior of the sachet 1 , but water does not. Note that water is usually condensed in the interior of containers of perishable products. Other functions of the plastic material are tear resistance, abrasion resistance or sealing capacity, for example by applying heat. Thus, the assembly is permeable to harmful gases and impermeable to water, to which end the gases to be filtered access the interior of the sachet 1 but water does not. The plastic material remains in the interior of the receptacle 2, in contact with the filtering material 3, and the sheet that provides rigidity remains on the outside of the receptacle 2, in contact with the gases to be absorbed. Note that, although the outer sheet can be humidified with water, water does not pass through the plastic material of the inner surface of the receptacle 2.

The plastic material is applied, joined, added or integrated in the form of a sheet or layer or of a treatment or deposit applied to the first sheet. In embodiments of the invention, the two materials (first sheet of gas-permeable material and second sheet or deposit of plastic material), are adhered, coupled or integrated without using any adhesive that alters the properties of the assembly. Non-limiting examples of types of coupling are extrusion, coextrusion, heat, molten plastic coating, spraying, pulverization or impregnation by spraying, inter alia. The possible elimination or reduction of adhesives simplifies the final product and makes it more environmentally friendly. Additionally, the elimination or reduction of adhesives facilitates the evaluation of the gas-permeability and water-impermeability of the sachet, upon eliminating the effect of the adhesives on said evaluation. In the case that the plastic material is added, integrated or coupled to the sheet that provides rigidity, by means of an adhesive, an adhesive permeable to harmful gases is chosen.

In a preferred embodiment, the first sheet is made of cellulose. Alternatively, the first sheet may be of any other gas-permeable material and that provides rigidity, such as for example non-woven fabric or Tyvek®.

The plastic material comprised in the receptacle 2 -added to, or integrated with, the support sheet- can be chosen from the following plastic materials: ethylene-vinyl-acetate (EVA), ultra low-density polyethylene, low- density polyethylene, medium-density polyethylene, high-density polyethylene, low-density linear polyethylene, polypropylene, polybutylene, ionomers, polystyrene (PS) and mixtures thereof, or any other plastic material impermeable to water in any of its states and permeable to harmful gases.

The plastic material added to or integrated with the sheet may consist of one of the foregoing materials. In a preferred embodiment, the material is a low- density polyethylene (LDPE).

The inventors observed that reducing the amount of plastic material applied or added to the sheet of gas-permeable material, such as cellulose, increases permeability to harmful gases, thereby facilitating the entrance of these gases to the interior of the sachet for absorption by the granulate 3, while maintaining impermeability to water in any of its states. This makes it possible to improve the permeability of the receptacle 2 while reducing the amount of plastic used, with respect to conventional receptacles, formed from two superimposed sheets (a sheet of gas-permeable material, such as cellulose, and another sheet of plastic material, such as LDPE, of at least 35 microns), typically joined by means of an adhesive. Thus, the plastic material layer or deposit of the present invention has a weight or surface density (grammage) less than or equal to 20 g/m² (grams per square meter), such as less than 15 g/m², or between 5 and 12 g/m², or between 6 and 12 g/m², or between 6 and 11 g/m², or between 7 and 1 1 g/m², or between 7 and 10 g/m², or between 8 and 10 g/m², inclusive. It was observed that choosing a plastic sheet with a weight lower than or equal to 20 g/m², increased the gas-permeability of the receptacle 2, without affecting impermeability to water in any of its states.

In embodiments of the invention, the thickness of the plastic sheet or deposit is chosen less than 25 pm (microns, 10⁶ m). In embodiments of the invention, this thickness is chosen between 5 and 25 pm, such as between 5 and 20 pm, or between 5 and 15 pm, or between 5 and 12 pm, or between 8 and 12 pm, or between 10 and 12 pm, inclusive.

The thickness of the plastic sheet or deposit may be constant or irregular. In the event of being irregular, the foregoing thickness value ranges are average values of the plastic sheet of irregular thickness.

In embodiments of the invention, the first sheet, i.e. the sheet that provides rigidity to the receptacle 2, while being gas-permeable, has a weight or surface density between 30 and 80 g/m², such as between 40 and 70 g/m², or between 40 and 60 g/m², or between 45 and 55 g/m².

In a possible embodiment, wherein the sheet of gas-permeable material is made of cellulose and the plastic added is LDPE, the receptacle 2 has an amount of 50 g/m² of cellulose and 10 g/m² of LDPE.

The interior of the sachet 1 is filled with a filtering material 3 formed by an impregnated porous substrate. In embodiments of the invention, no type of adhesive or of any other material is used to join the sheet, for example cellulose, and the plastic material, for example polyethylene.

Returning to figure 1 , a plurality of grains or granules or, in other words, a granulate 3, has been introduced in the interior of the sachet 1. Alternatively, the filtering material 3 housed in the receptacle 2 is powder of said material. The granulate or plurality of grains or granules 3, or powder, provide the filtering capacity of the sachet 1 , i.e. they absorb the unwanted gases. Therefore, said gases must penetrate through the walls 2 of the sachet 1 , i.e. of the cellulose sheet with polyethylene in the event that the walls 2 are made of those materials, with the highest possible permeability.

As mentioned earlier, the granulate or plurality of grains or granules 3 comprise a porous substrate and an impregnation of the porous substrate. The porous substrate used to form the granulate can be made of the following materials: diatomaceous earth; natural or synthetic zeolites of any type; molecular sieve; xylitol; perlite; aluminas and active aluminas; mica; magnesium aluminate; aluminosilicate; magnesium silicate; activated carbon; absorbent clays, such as bentonite, sepiolite, attapulgite, vermiculite, etc., kaolin; activated bauxite; silica gel; or mixtures of the foregoing materials. The percentage of impregnation applied to the filtering granulate may vary. The impregnation may be of the following types: potassium permanganate; sodium permanganate; lithium permanganate; magnesium permanganate; calcium permanganate; barium permanganate; or any purple-color permanganate. Alternatively, the granules 3 may be obtained by combining substrates impregnated with non- impregnated substrates, from the aforementioned substrates; adding other chemical compounds as impregnating agents (for example, bicarbonate), provided that a permanganate is added; combining substrates impregnated with permanganate (and adding one or no chemical compound) with substrates with other impregnations (such as KOH, NaOH or others); or combining the different previously described possibilities (for example, mixing together three or more types of granulate).

When the filtering material is a granulate, the grains or granules 3 may adopt any shape, such as spherical, cylindrical, in pellet form or an irregular shape. When the grains are spherical, their diameter may range between 1 and 7 mm (millimeters, 10^-3 meters), such as between 3 and 5 mm.

The sachet 1 filled with a filtering material 3, and the walls 2 of which are formed from a sheet of a material permeable to harmful gases, such as cellulose, whereto a plastic material impermeable to water in any of its states and permeable to harmful gases, such as low density polyethylene, has been joined, added, integrated or impregnated, for example by means of extrusion or coextrusion, provides greater permeability to gases, particularly to ethylene, without affecting impermeability to water in any of its states, with respect to sachets formed by the adhesion of a cellulose sheet and a at leasta 35 pm thick -polyethylene sheet.

The following experiment was conducted: Various sachets formed by a 50 g/m² cellulose sheet joined to or integrated with a 10 g/m² LDPE sheet, and various conventional sachets, i.e. formed by a 40 g/m² cellulose sheet adhered to a 35 pm thick LDPE sheet, were introduced in an airtight receptacle with an ethylene emission source (high-emitting fruit). All the sachets had an identical batch and quantity of filtering granulate in their interior. It is known that the small difference between the amount of cellulose of the two sachet types does not affect the permeability of the sachets to harmful gases and impermeability to water. The degree of saturation of the granulate housed in the interior of the sachets, expressed through a change in color, was observed over a certain time period (48 hours). Thus, the sachets with a 10 g/m² plastic sheet exhibited higher saturation of the granulate compared to conventional sachets. In this manner, the measurement of permeability of the sachets of the invention compared to conventional sachets was obtained. Note that all the sachets were housed in the same recipient, due to which the different variables, such as gas pressure or concentrations, were identical for all of them. A significant increase in permeability to ethylene was observed in the sachets of the invention. It follows that permeability to ethylene, and therefore the effectiveness of the sachet, is derived both from the thickness of its layers, and from its permeability to water, including permeability to water vapor.

The following experiment was also conducted to evaluate the migration of water molecules towards the interior of the sachet in contact with water: Various sachets formed from a 50 g/m² cellulose sheet joined to or integrated with a LDPE sheet of different weights ranging between 10 g/m² and 6 g/m² were immersed in receptacles with water. All the sachets had an identical batch and quantity of filtering granulate in their interior. More than one month was allowed to elapse to observe whether the water turned purple from the migration of the water with permanganate. In all cases it was observed that the water did not turn purple, i.e. it was concluded that there was no migration of water towards the interior of the sachet. Indeed, it was observed that the water molecules seemed to migrate through the sachet only when it was broken, regardless of the weight of the LDPE.

Lastly, the migration of water molecules towards the interior of Tyvek® sachets in contact with water was evaluated through the following experiment: Various conventional Tyvek® sachets containing a filtering granulate comprising permanganate were immersed in receptacles with water. More than one month was allowed to elapse and a slow migration of water molecules through the Tyvek® was observed, observing that the granulate became wet, losing its effectiveness, and that water with permanganate migrated towards the exterior of the sachet.

The described sachet for absorbing harmful gases 1 is intended for being inserted in the interior of a packaging or packing (bags, boxes, etc.) wherein perishable products have been stored or packaged. In this text, the term "comprises" and its derivations (such as "comprising", etc.) should not be understood in an excluding sense, i.e. these terms should not be interpreted as excluding the possibility that what is described and defined may include elements, additional stages, etc.

In the context of the present invention, the term "approximately" and terms of its family (such as "approximate", etc.) must be interpreted as indicating values very near those that accompany said term. That is, a deviation within reasonable limits with respect to an exact value should be accepted, because a person skilled in the art will understand that such deviation may be inevitable with respect to the indicated values due to inaccurate measurements, etc. The same applies to the terms "some", "around" and "substantially".

The invention is obviously not limited to the described specific embodiment(s), but rather encompasses any variation that may be considered by any person skilled in the art (for example, in relation to the choice of materials, dimensions, components, configuration, etc.), within the general scope of the invention as defined in the claims.

Claims

1. A gas-absorption sachet (1 ) comprising a receptacle (2) that houses a filtering material (3) in its interior for absorbing harmful gases,

characterized in that the receptacle (2) is formed from a sheet that provides rigidity, said sheet being made of a material permeable to harmful gases, joined to or integrated with a plastic material impermeable to water and permeable to harmful gases, the weight of the plastic material being less than or equal to 20 g/m²

2. The sachet (1 ) of claim 1 , wherein said sheet that provides rigidity, made of a material permeable to harmful gases, is a cellulose sheet or non-woven fabric sheet.

3. The sachet (1 ), of any one of claims 1 or 2, wherein the plastic material impermeable to water and permeable to harmful gases is chosen from the following plastic materials: ethylene-vinyl-acetate (EVA), ultra low-density polyethylene, low-density polyethylene, medium-density polyethylene, high- density polyethylene, low-density linear polyethylene, polypropylene, polybutylene, ionomers, polystyrene (PS) and mixtures thereof.

4. The sachet (1 ) of any one of the preceding claims, wherein the plastic material has been joined to the sheet that provides rigidity by extrusion, coextrusion, heat, molten plastic coating, spraying, pulverization or impregnation by spraying.

5. The sachet (1 ) of any one of the preceding claims, wherein the weight of the plastic material is less than or equal to 20 g/m².

6. The sachet (1 ) of claim 5, wherein the weight of the plastic material is less than or equal to 15 g/m².

7. The sachet (1 ) of claim 6, wherein the weight of the plastic material is between 5 and 12 g/m².

8. The sachet (1 ) of claim 7, wherein the weight of the plastic material is between 6 and 12 g/m²

9. The sachet (1 ) of claim 8, wherein the weight of the plastic material is between 6 and 11 g/m².

10. The sachet (1 ) of claim 9, wherein the weight of the plastic material is between 7 and 11 g/m².

11. The sachet (1 ) of claim 10, wherein the weight of the plastic material is between 7 and 10 g/m².

12. The sachet (1 ) of claim 11 , wherein the weight of the plastic material is between 8 and 10 g/m².

13. The sachet (1 ) of any one of claims 1 to 5, wherein the thickness of the plastic material is less than 25 pm.

14. The sachet (1 ) of claim 13, wherein the thickness of the plastic material is between 5 and 25 pm.

15. The sachet (1 ) of claim 14, wherein the thickness of the plastic material is between 5 and 20 pm.

16. The sachet (1 ) of claim 15, wherein the thickness of the plastic material is between 5 and 15 pm.

17. The sachet (1 ) of claim 16, wherein the thickness of the plastic material is between 5 and 12 pm.

18. The sachet (1 ) of claim 17, wherein the thickness of the plastic material is between 8 and 12 pm.

19. The sachet (1 ) of claim 18, wherein the thickness of the plastic material is between 10 and 12 pm.

20. The sachet (1 ) of any one of the preceding claims, wherein the weight of the sheet that provides rigidity, made of a gas-permeable material, is between 30 and 80 g/m²

21. The sachet (1 ) of claim 20, wherein said weight is between 40 and 70 g/m².

22. The sachet (1 ) of claim 21 , wherein said weight is between 40 and 60 g/m²

23. The sachet (1 ) of claim 22, wherein said weight is between 45 and 55 g/m².

24. The sachet (1 ) of any one of the preceding claims, wherein no type of adhesive or of any other material is used to join or integrate the sheet that provides rigidity and the plastic material.

25. The sachet (1 ) of any one of claims 1 to 23, wherein an adhesive permeable to harmful gases is used to join or integrate the sheet that provides rigidity and the plastic material.

26. The sachet (1 ) of any one of the preceding claims, wherein the filtering material (3) comprises an impregnated porous substrate.

27. The sachet (1 ) of any one of the preceding claims, wherein the filtering material (3) is a granulate or powder.

28. The sachet (1 ) of any one of the preceding claims, wherein the filtering material (3) comprises a granulate formed from grains whose diameter is between 1 and 7 mm.

29. The sachet (1 ) of any one of the preceding claims, wherein the plastic material remains in the interior of the receptacle (2), in contact with the filtering material (3), and the sheet that provides rigidity remains on the outside of the receptacle (2), in contact with the gases to be absorbed.

30. A packaging for packing perishable products comprising a sachet (1 ) according to any one of the preceding claims.