Transparent film, permeable to gases and impermeable to water, particularly for applications in the medical field.

Abstract

- Transparent, gas-permeable, and water-impermeable film, particularly for medical applications. - The film (1) comprises a polyolefin base (3), to which is added a monomeric plasticizer (4) with a mass percentage between 10% and 50%, and preferably also molecular sieves (5) with a mass percentage less than or equal to 20%. This addition notably increases the gas permeability of the film (1). The film (1) thus exhibits high gas permeability, low water permeability, and high transparency, as well as various mechanical characteristics and properties, making it particularly well-suited to numerous applications, especially in the medical sector, and in particular for use on identification cards used in medical diagnosis. Figure for the abstract: Fig. 2

Description

Title of the invention: Transparent film, permeable to gases and impermeable to water, particularly for applications in the medical field. technical field

[0001] The present invention relates to a transparent, gas-permeable, and water-impermeable film, particularly for applications in the medical field. PRIOR TECHNOLOGY

[0002] Although not exclusively, the transparent, gas-permeable and water-impermeable film is applied, more particularly, to an identification card used in an identification test implemented during medical diagnoses to identify bacteria.

[0003] It is known that, in the field of medical diagnosis, the medical profession often relies on the results of bacterial identification tests and antibiograms to determine the most appropriate antibiotic treatment for a patient's condition and to monitor the evolution of antibiotic resistance in these bacteria. These identification tests make it possible to determine, quickly and reliably, the pathogen responsible for an infection.

[0004] To perform such identification tests, identification cards are required. These disposable, single-use identification cards allow for the rapid and accurate identification of a wide range of clinically relevant bacterial and yeast species. Each identification card is equipped with microwells containing identification substrates. To perform an identification test, the solution to be analyzed is injected into channels of the identification card, and the entire assembly is then placed in an incubator. The plates are subsequently analyzed using various standard methods.

[0005] In order to protect the culture medium from any external pollution, each identification card is secured by being sealed on both sides with a transparent adhesive film.

[0006] The transparent adhesive film used for this purpose must have specific and strict characteristics, including: - sufficient permeability to gases (oxygen, carbon dioxide) to allow bacterial growth and diagnosis; - low water permeability to limit evaporation of the culture medium; - high transparency to enable readings at defined wavelengths; and - special mechanical characteristics to be able to transform the films without deforming them.

[0007] Generally, polymethylpentene (PMP) films are used for such applications. These polymethylpentene films, however, have fixed given values ​​for the aforementioned characteristics.

[0008] Also, there is an interest and a need to be able to modify the values ​​of these film characteristics in order to adapt them more precisely to those actually required for the applications envisaged. Description of the invention

[0009] The present invention aims to provide a transparent film, permeable to gases and impermeable to water, suitable for use in particular in the aforementioned applications and to meet this need.

[0010] According to the invention, said film comprises a polyolefin base (matrix), to which is added at least one monomeric plasticizer with a mass percentage of the monomeric plasticizer between 10% and 50%, and preferably between 15% and 45%.

[0011] In a preferred embodiment, said film further comprises molecular sieves with a mass percentage less than or equal to 20%, and preferably less than or equal to 10%.

[0012] Thus, thanks to the invention, a film is obtained which exhibits, in particular, as specified below, high permeability to gases (oxygen, carbon dioxide), low permeability to water (liquid), and high transparency, as well as various mechanical characteristics and properties. Depending on the proportion of the elements (monomeric plasticizer, molecular sieve) added to the polyolefin base, the properties of the film can be modified and adapted to the properties required for the intended applications.

[0013] This film is particularly well suited for use on an identification card as described above. However, thanks to its surprising and advantageous characteristics, the film can also be used in many other applications, particularly in the medical field, but not exclusively.

[0014] Advantageously, the polyolefin matrix corresponds to one of the following components: a homopolymer PP (in polypropylene) or a block or statistical copolymer PP / PE (polypropylene PP and polyethylene PE).

[0015] In addition, advantageously, the monomeric plasticizer is dioctyl sebacate (DOS for "dioctyl sebacate" in English).

[0016] Furthermore, advantageously, the molecular sieves are made of at least one of the following materials: cyclodextrins (CD), zeolites, silsesquioxanes polyhedral oligomers (POSS for "polyhedral oligomeric silsesquioxane" in English), metal-organic frameworks (MOF for "metal organic frameworks" in English), covalent organic frameworks (COF for "covalent organic frameworks" in English).

[0017] Furthermore, in a particular embodiment: - the film has a thickness between 25 µm and 100 µm; and / or - it is provided on at least one of its faces with a layer of adhesive so that it can be easily glued onto a support. BRIEF DESCRIPTION OF THE FIGURES

[0018] Other advantages and features will become clearer from the following description of several embodiments, given by way of non-limiting examples, of a film according to the invention, with particular reference to the accompanying figures. In these figures, identical reference numerals designate similar elements.

[0019] Fig. 1 is a partial schematic cross-sectional view of a transparent, gas-permeable and water-impermeable film according to a first embodiment of the invention.

[0020] Fig. 2 is a partial schematic cross-sectional view of a transparent, gas-permeable and water-impermeable film according to a second preferred embodiment of the invention. DETAILED DESCRIPTION

[0021] The film 1 used to illustrate the invention and represented in two different embodiments in Figures 1 and 2 is a transparent film, permeable to gases and impermeable to water, as specified below.

[0022] In the first embodiment shown in [Fig. 1], the film 1 is formed of a material 2 comprising a polyolefin base (matrix) 3, schematically illustrated by a white background in Figures 1 and 2, and a monomeric plasticizer 4, schematically illustrated by dashed hatching, which has been added (mixed) to the polyolefin base 3. The monomeric plasticizer 4, which is distributed (mixed), preferably uniformly, in the polyolefin base 3, has a mass percentage of between 10% and 50%, and preferably between 15% and 45%, of the total mass of the material 2 of the film 1.

[0023] Furthermore, in the second embodiment (which is the preferred embodiment), the film 1 is also formed, as shown in [Fig. 2], from a material 2 comprising a polyolefin base (matrix) 3, to which a monomeric plasticizer 4 is added. The monomeric plasticizer 4, which is distributed, preferably uniformly, in the polyolefin base 3, also has a mass percentage of between 10% and 50%, and preferably between 15% and 45%, of the total mass of the material 2 of film 1.

[0024] In this second (preferred) embodiment, the material 2 of the film 1 further comprises molecular sieves 5, schematically illustrated by black dots in [Fig. 2]. These molecular sieves 5, specified below, are distributed, preferably uniformly, in the polyolefin base (matrix) 3 of the material 2. The molecular sieves 5 have a mass percentage that is less than or equal to 20% and preferably less than or equal to 10% of the total mass of the material 2 of the film 1.

[0025] The addition of the monomeric plasticizer 4 and the molecular sieves 5 produces a surprising effect, particularly in terms of (high) gas permeability, allowing advantageous characteristics to be obtained.

[0026] As specified below, the film 1 made of material 2 has the following characteristics and advantages: - high transparency, as illustrated in figures 1 and 2 by arrows H crossing film 1, with a transmittance greater than 85% at 428 nm; - a low permeability to water (H2O), less than 1.66E-12 mol.m / (m2.s.Pa) (or less than 5000 barred), as illustrated in figures 1 and 2 by arrows F stopped by film 1. In the context of the present invention, a value denoted "xEy" is equal to "x. 10'"; - high permeability to carbon dioxide (CO2), greater than 1.66E-14 mol.m / (m2.s.Pa) (or greater than 50 bar); and - a high permeability to oxygen O2, greater than 3.35E-15 mol.m / (m2.s.Pa) (or greater than 10 barred).

[0027] These high gas permeabilities are illustrated in Figures 1 and 2 by arrows G crossing film 1.

[0028] The film 1 made of material 2 also has the following characteristics: - a deformation at break of between 30% and 500%; and - a Young's modulus greater than 5.00E+07 Pa (or kg / (m.s2)).

[0029] These latter characteristics make the film 1 flexible and manipulable, and in particular sufficiently manipulable for the applications envisaged.

[0030] In each of the formulation modes, the polyolefin matrix 3 corresponds to one of the following components: - a homopolymer PP (polypropylene); - a block or statistical copolymer PP / PE (polypropylene PP and polyethylene PE).

[0031] The polyolefin matrix 3 (starting) makes it possible, in particular for film thicknesses E 1 between 25 and 100 pm, to meet the transparency criteria required for the envisaged applications and to provide sufficient hydrophobicity to guarantee low water fluxes (in the liquid state).

[0032] Furthermore, the polyolefin matrix 3 can be easily melt-processed. A melt-process is preferably used for both the various formulation steps of the material 2 and for shaping the film 1. Such a process has the particular advantage of a low environmental impact compared to a solvent-based process and is economically advantageous from an industrial perspective. Therefore, preferably, all modifications to the polymers used are carried out using a melt process.

[0033] In addition, the additives (the monomeric plasticizer 4 and the molecular sieves 5) incorporated into the polyolefin matrix 3 exhibit sufficient thermal stability for the conditions of melt processing and allow for the maintenance of low water permeability.

[0034] A polyolefin matrix 3 such as that used in the context of the present invention thus has, in particular, the following characteristics and advantages: - high transparency; - water impermeability; - mechanical properties: flexible and non-extensible; and - an ability to be shaped by melting.

[0035] Furthermore, regardless of the embodiment considered, the monomeric plasticizer 4 (comprising low molecular weight organic molecules) which is added to the polyolefin matrix 3 is preferably dioctyl sebacate (DOS for "dioctyl sebacate" in English).

[0036] The addition of the monomeric plasticizer 4 to the polyolefin matrix 3, without degrading the optical properties of the polyolefin matrix 3, makes it possible to increase its gas permeability through the plasticization of the polymer chains of the polyolefin matrix 3.

[0037] To improve the gas permeability of the polyolefin matrix 3, low molecular weight organic molecules are added, which notably increase the mobility of the polymer chains. An increase in the mobility of these chains, or more generally of the permeation medium, leads to an increase in permeability.

[0038] Furthermore, in said second (preferred) embodiment, the molecular sieves 5 that are added correspond to at least one of the following materials: - cyclodextrins (CD); - zeolites; - polyhedral oligomeric silsesquioxanes (POSS for "polyhedral oligomeric silsesquioxane" in English); - metal-organic networks (MOFs for "metal organic frameworks" in English); - covalent organic frameworks (COF for "covalent organic frameworks") in English).

[0039] In particular, the use of molecular sieves and more particularly of zeolites (which have little influence on mechanical properties except for deformation at break) is very advantageous.

[0040] In the second embodiment, the gas permeability of the film 1 is greatly increased by the addition of both the monomeric plasticizer 4 and the molecular sieves 5, while retaining sufficient mechanical and optical properties for the intended applications.

[0041] In a first embodiment, the molecular sieves 5 are all made of one and the same material, among the aforementioned materials.

[0042] Furthermore, in a second embodiment, the material 2 comprises at least two different types of molecular sieves 5, of which a first type is made in a first material (among the aforementioned materials) and of which a second type is made in a second material (among the aforementioned materials) different from said first material.

[0043] In the context of the present invention, the molecular sieves 5 have a mass percentage which is between 0% (first embodiment) and 20%, and preferably between 0% and 10%, of the total mass of the material 2 of the film 1.

[0044] The table below highlights the main characteristics of film 1 for four different formulations Fl, F2, F3 and F4 of material 2. Formulation Elastic Modulus Elastic Stress Tensile Strength Elastic Deformation Deformation at Break O2 Permeability CO2 Permeability Liquid H2O Permeability Transmittance at 428 nm (MPa) (MPa) (MPa) (%) (%) (57) (57) (57) (%) Fl 146 12 12 32 271 4.45E- 15 1.74E- 14 7.76E- 13 90 F2 73 12 12 30 260 8.63E- 15 2.26E- 14 8.88E- 13 88 F3 186 32 16 27 256 3.52E- 15 1.809E -14 l.07E- 12 89 F4 179 10 13 30 286 4.32E- 15 2.881E -14 6.56E- 13 90

[0045] This table presents the values ​​of at least some of the parameters considered for the different formulations Fl, F2, F3 and F4.

[0046] In this table, the formulations Fl and F2 relate to the first mode of rea The formulation ([Fig. 1]) comprises a mixture of polyolefin base 3 and monomeric plasticizer 4, and formulations F3 and F4 relate to the second embodiment ([Fig. 2]) comprising a mixture of polyolefin base 3, monomeric plasticizer 4 and molecular sieves 5. Furthermore, in this case: - the polyolefin base 3 is a PP / PE copolymer of MFI 1 to 8; - Monomeric plasticizer 4 is from DOS; and - molecular sieves 5 are either NaY zeolite or NaX zeolite.

[0047] More specifically: - Fl concerns a mixture of PP / PE copolymer and 25% DOS; - F2 relates to a mixture of PP / PE copolymer and 35% DOS; - F3 concerns a mixture of PP / PE copolymer, 18% DOS and 6% NaY; and - F4 relates to a mixture of PP / PE copolymer, 21% DOS and 8% NaX.

[0048] This table highlights the following advantageous characteristics of the different formulations: - high permeability to gases (oxygen O2, carbon dioxide CO2), expressed in the International System SI, namely in mol.m / (m2.s.Pa); - low permeability to water H2O in the liquid state, also expressed in mol.m / (m2.s.Pa); - high transparency, namely a transmittance for a wavelength of 428 nm, expressed as a percentage; and - specific mechanical characteristics, namely the elastic modulus, elastic stress and breaking stress expressed in MPa, as well as the elastic deformation and breaking deformation expressed in %.

[0049] All four formulations Fl to F4 thus exhibit good gas permeability properties. In addition, formulations F3 and F4 exhibit improved mechanical properties.

[0050] An example of a manufacturing process for a film 1 such as that described above is presented below.

[0051] During the implementation of this manufacturing process, a first melting of the polyolefin matrix 3 is carried out.

[0052] Then, the components corresponding to the embodiment concerned are added to the molten polyolefin matrix 3, and the whole is mixed in a conventional mixer.

[0053] Thus, to manufacture the material 2 according to the first embodiment, the monomeric plasticizer 4 is added to the polyolefin matrix 3, and the whole is mixed.

[0054] Furthermore, to manufacture the material 2 according to the second embodiment, both the monomeric plasticizer 4 and the molecular sieves 5 are added to the polyolefin matrix 3, and the whole is mixed.

[0055] In this case, the monomeric plasticizer 4 and the molecular sieves 5 can be added simultaneously to the polyolefin matrix 3. The monomeric plasticizer 4 and the molecular sieves 5 can also be added successively to the polyolefin matrix 3, starting with the monomeric plasticizer 4 or with the molecular sieves 5, depending on the manufacturing method envisaged.

[0056] The different stages (melting, mixing) of the manufacturing process are implemented in the usual way.

[0057] When the mixture is homogeneous, the material 2 obtained is transformed and shaped in the usual way, in the molten state, for example by means of an extrusion operation, to obtain the film 1 having the desired characteristics, in particular in terms of thickness.

[0058] By way of illustration, for use on an identification card, the thickness E (figures 1 and 2) of the film 1 can be between 25 µm and 100 µm.

[0059] As indicated above, such a melt manufacturing process (for the manufacture of material 2 and the shaping of film 1) has the particular advantage of having a low environmental impact compared to a solvent-phase process and is economically attractive from an industrial point of view.

[0060] In a particular embodiment, an adhesive layer (not shown) is applied, in a conventional manner, to at least one of the faces IA and IB of the film 1. The adhesive film 1 thus obtained can then be easily bonded to a substrate for the intended application.

[0061] Film 1, as described above, is particularly well suited for use on an identification card, thanks to its following characteristics: - a permeability to gases (oxygen, carbon dioxide) which is sufficient to allow bacterial growth and diagnosis; - a permeability to water (liquid) which is sufficiently low to limit the evaporation of the culture medium; - a transparency that is high enough to allow readings to be taken at defined wavelengths; and - mechanical characteristics that allow the film to be transformed without deforming it.

[0062] The film 1, as described above, can also be used in many other applications, particularly (but not exclusively) in the medical sector and especially in the field of diagnostics. More generally, the film 1 can be used in all applications where its advantageous characteristics, and in particular its high gas permeability (allowing gas exchange while exhibiting water barrier properties), are desired.

[0063] It is quite clear that the examples presented above are only illustrations specific, but in no way limiting, features of the present invention. Furthermore, features of some of these different examples may be combined, if appropriate, without departing from the scope of the present invention.

Claims

Demands

1. Transparent, water-impermeable and gas-permeable film, characterized in that it comprises a material (2) having a polyolefin base (3), to which is added at least one monomeric plasticizer (4) with a mass percentage of the monomeric plasticizer (4) between 10% and 50% of the total mass of the material (2) of the film (1), in that the polyolefin base (3) corresponds to one of the following components: a PP homopolymer or a PP / PE block or statistical copolymer, and in that the film (1) has a transmittance greater than 85% at 428 nm.

2. Film according to claim 1, characterized in that the mass percentage of the monomeric plasticizer (4) is between 15% and 45% of the total mass of the material (2) of the film (1).

3. Film according to any one of claims 1 and 2, characterized in that the material (2) of the film (1) further comprises molecular sieves (5) with a mass percentage less than or equal to 20% of the total mass of said material (2).

4. Film according to claim 3, characterized in that the mass percentage of the molecular sieves (5) is less than or equal to 10% of the total mass of the material (2) of the film (1).

5. Film according to any one of the preceding claims, characterized in that the monomeric plasticizer (4) is dioctyl sebacate.

6. Film according to any one of claims 3 to 5, characterized in that the molecular sieves (5) are made of at least one of the following materials: cyclodextrins, zeolites, polyhedral oligomeric silsesquioxanes, metal-organic networks, covalent organic frameworks.

7. Film according to any one of the preceding claims, characterized in that it has a thickness (E) between 25 µm and 100 µm.

8. Film according to any one of the preceding claims, characterized in that it is provided on at least one of its faces (IA, IB) with a layer of adhesive.

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