FR3052167A1 - COMPOSITION BASED ON FLUORINE GRAFT POLYMER AND USE THEREOF FOR LIMITING BATTERY PROLIFERATION - Google Patents

Abstract

The present invention relates to a composition based on grafted fluoropolymer and its use for limiting bacterial proliferation in an aqueous medium. The invention also relates to a hollow body, in particular a pipe or a composite tube, able to contain water, in particular drinking water, whose inner layer in contact with water consists of said composition.

Description

The present invention relates to a composition based on grafted fluoropolymer and its use for limiting bacterial proliferation in an aqueous medium. The invention also relates to a hollow body, in particular a pipe or a composite tube, able to contain water, in particular drinking water, whose inner layer in contact with water consists of said composition.

Fluorinated polymers, especially PVDF, are known to be materials limiting bacterial proliferation. Thus, the document "Fluoropolymers Applications in Chemical Processing Industries - The Definitive User's Guide and Databook" (ISBN-13: 978-0815515029) indicates that a biofilm is more difficult to form on the surface of PVDF than on the surface stainless steel.

Furthermore, WO 2008/009865 discloses a fluoropolymer grafted with a particular ionic monomer and recommends the use thereof for the manufacture of a tube or container that can be used to store or transport a fluid (liquid or gas) and which one wants to avoid the bacterial contamination.

However, in the case of pipes or containers, in particular drinking water transport pipes and drinking water containers, the antibacterial action of the material forming the inner layer of the pipe or the container is not sufficient. to ensure a long lasting protective effect. Indeed, it has been found that the poor attachment of the biofilm formed on the inner surface of the pipe or container also plays an important role in the antimicrobial effect. Thus, even if the thickness of the biofilm created on the surface in contact with water is low, it can cause problems of bacterial contamination of the water if it can not be regularly and correctly removed. This is particularly true for potable water transport pipelines that are buried in the ground and for which no mechanical cleaning action can be easily implemented.

There is therefore a real need for new materials having a satisfactory and constant antibacterial activity over time and on which the bacteria have a weak grip.

An object of the present invention is to provide a composition which has antimicrobial properties, said composition being intended to form the inner layer of an object in contact with water or an aqueous medium, in order to prevent or limit the proliferation thereof of microorganisms.

Another object of the invention relates to the use of said composition for limiting the bacterial proliferation in an aqueous medium, as an inner layer in a hollow body for storing or transporting water, especially drinking water.

Another subject of the invention relates to a hollow body, such as a water storage container, a pipe or a composite tube for transporting water, in particular drinking water, whose inner layer in contact with the water has a satisfactory antibacterial activity and on which the bacteria have a weak grip.

Another object of the invention is to provide a simple manufacturing method to implement and inexpensive to manufacture the aforementioned hollow body.

Another subject of the invention relates to the use of a fluoropolymer, grafted with a particular unsaturated monomer, to limit the bacterial proliferation in an aqueous medium, for example as an inner layer in a hollow body for storing or transporting water. water, especially drinking water.

The present invention relates, in a first aspect, to a composition comprising a fluoropolymer grafted with maleic acid anhydride functional groups and at least one block copolymer comprising at least one hydrophobic block and at least one hydrophilic block. Regarding the fluoropolymer is thus denoted any polymer having in its chain at least one monomer chosen from compounds containing a vinyl group capable of opening to polymerize and which contains, directly attached to this vinyl group, at least one atom fluorine, a fluoroalkyl group or a fluoroalkoxy group. By way of example of monomer, mention may be made of vinyl fluoride; vinylidene fluoride (VDF); trifluoroethylene (VF3); chlorotrifluoroethylene (CTFE); 1,2-difluoroethylene; tetrafluoroethylene (TFE); hexafluoropropylene (HFP); perfluoro (alkyl vinyl) ethers such as perfluoro (methyl vinyl ether (PMVE), perfluoro (ethyl vinyl) ether (PEVE) and perfluoro (propyl vinyl) ether (PPVE), perfluoro (1,3-dioxole); perfluoro (2,2-dimethyl-1,3-dioxole) (PDD), the product of formula CF2 = CFOCF2CF (CF3) OCF2CF2X wherein X is SO2F, CO2H, CH20H, CH20CN or CH20PO3H, the product of formula CF2 = CFOCF 2 CF 2 SO 2 F, the product of formula F (CF 2) nCH 2 OCOF = CF 2 in which n is 1, 2, 3, 4 or 5, the product of formula R 1 CH 2 OCOF = CF 2 in which R 1 is hydrogen or F (CF 2) z and z is 1, 2, 3 or 4, the product of formula R30CF = CH2 wherein R3 is F (CF2) z- and z is 1, 2, 3 or 4; perfluorobutyl ethylene (PFBE); 3,3,3-trifluoropropene; and 2-trifluoromethyl-3,3,3-trifluoro-1-propene.

The fluoropolymer may be a homopolymer or a copolymer, it may also include non-fluorinated monomers such as ethylene. By way of example, the fluoropolymer is chosen from: homo-and copolymers of vinylidene fluoride (VDF) preferably containing at least 50% by weight of VDF, the copolymer being chosen from chlorotrifluoroethylene (CTFE), hexafluoropropylene (HFP), trifluoroethylene (VF3) and tetrafluoroethylene (TFE), homo-and copolymers of trifluoroethylene (VF3), copolymers, and especially terpolymers, combining the residues of the chlorotrifluoroethylene (CTFE), tetrafluoroethylene (TFE) units ), hexafluoropropylene (HFP) and / or ethylene and optionally VDF and / or VF3 units.

Advantageously, the fluoropolymer is polyvinylidene fluoride (PVDF) homopolymer or copolymer. Preferably the PVDF contains, by weight, at least 50% of VDF, more preferably at least 75% and more preferably at least 85%.

Advantageously, the fluoropolymer is a thermoplastic polymer (as opposed to a fluoroelastomer). Fluoropolymers containing a high proportion of units derived from the VDF monomer tend to be thermoplastic.

By "thermoplastic" is meant here a non-elastomeric polymer. An elastomeric polymer is defined as a polymer that can be stretched at room temperature to twice its original length and, after stress relief, quickly resumes its initial length to within 10% as indicated by ASTM in Special Technical Publication No. 184.

Advantageously, the PVDF has a viscosity ranging from 100 Pa.s to 2000 Pa s, the viscosity being measured at 230 ° C., at a shear rate of 100 s using a capillary rheometer. Indeed, these PVDF are well suited to extrusion and injection. Preferably, the PVDF has a viscosity ranging from 300 Pa.s to 1200 Pa.s, the viscosity being measured at 230 ° C., at a shear rate of 100s-1 using a capillary rheometer. Thus, the PVDF marketed under the trademark KYNAR® 710 or 720 are perfectly suited for this formulation.

According to one embodiment, the composition according to the invention consists of a fluoropolymer grafted with maleic acid anhydride functional groups and at least one block copolymer comprising at least one hydrophobic block and at least one hydrophilic block.

The unsaturated monomer grafted on said fluoropolymer is maleic acid anhydride. The grafting method is described by the Applicant in the document EP 1 484 346. In short, the method of grafting an unsaturated monomer onto a fluoropolymer comprises the following steps: a) mixing the fluoropolymer in the molten state with the unsaturated monomer, (b) the mixture obtained in (a) is formed into films, slabs, granules or powder; (c) the products of step (b) are subjected, in the absence of air, to at a photon (γ) or electron (β) irradiation at a dose of between 1 and 15 Mrad, d) the product obtained in c) is optionally treated to remove all or part of the unsaturated monomer which has not been grafted onto the fluorinated polymer.

The maleic anhydride content in the grafted fluoropolymer varies from 0.2 to 1.0%, and preferably from 0.4% to 0.7% by weight relative to the total weight of the fluoropolymer.

According to one embodiment, said grafted fluoropolymer is a homopolymer of vinylidene fluoride which comprises, by weight, from 0.2 to 1.0%, and preferably from 0.4% to 0.7%, of maleic acid. Such a polymer has good antibacterial properties and prevents the adhesion of bacteria to the surface of the layer that contains it. According to another aspect, the invention relates to the use of a fluoropolymer grafted with maleic anhydride functions, for limiting the bacterial proliferation on a surface in an aqueous medium, in particular as an inner layer in a hollow body used for store or transport water, especially drinking water. According to one embodiment, said use is that of a PVDF grafted with 0.2 to 1.0%, and preferably from 0.4% to 0.7%, by weight, of maleic acid.

Advantageously, said grafted fluoropolymer according to the invention having an antibacterial activity can be shaped with the thermoplastic transformation tools usually used in the plastics industry; it does not release an antibacterial agent in the medium to be protected and preserves over time its antibacterial activity. As regards the block copolymer used in the antibacterial composition according to the invention, it comprises at least one hydrophilic block capable of being obtained from monomers of n-butyl acrylate and of hydroxyethyl methacrylate, and at least a hydrophobic block obtainable from a methyl methacrylate monomer.

By "hydrophilic block" is meant a copolymer soluble in water, dispersible in water, or which generally has the capacity to absorb and / or release water. The hydrophilic block can be a random copolymer containing at least said hydrophilic monomers of n-butyl acrylate and hydroxyethyl methacrylate, and optionally other hydrophilic monomers, or a random copolymer containing at least said hydrophilic monomers, and optionally one or more other hydrophilic monomers, with one or more hydrophobic monomers.

By "hydrophobic block" is meant here a (co) polymer insoluble or non-dispersible in water. The hydrophobic block may be a hydrophobic homopolymer, a random copolymer containing at least said methyl methacrylate monomer and one or more other hydrophobic monomers, or a random copolymer containing at least said methyl methacrylate monomer, and optionally one or more hydrophobic monomers, with one or more hydrophilic monomers.

Preferred block copolymers of the invention are of the type in which at least: the hydrophilic block is composed of a random copolymer substantially containing monomers of n-butyl acrylate and hydroxyethyl methacrylate; preferably, the proportion by weight of n-butyl acrylate monomers in the first hydrophilic block is between 99 and 50%, preferably between 95 and 70%, and the proportion by weight of hydroxyethyl methacrylate monomers is between 1 and 50%, preferably between 5 and 30% (inclusive); the hydrophilic block preferably has a number-average molecular weight Mn of between 5 and 200 kg / mol and a weight-average molecular weight of between 10 and 400 kg / mol; and / or the hydrophobic block is composed of at least 50% of polymethyl methacrylate (PMMA), the remainder being formed of a mixture of methacrylate or acrylate monomers, preferably monomers of n-butyl acrylate and of hydroxyethyl methacrylate.

The block copolymer of the invention may have a weight average molecular weight of between 10 kg / mol and 400 kg / mol, preferably between 15 and 100 kg / mol, and a number-average molecular mass of between 7 and 50 kg. / mol. Its polydispersity index is preferably between 1.5 and 5. Block synthesis of the block copolymer of the invention can be carried out by any type of controlled radical polymerization.

Said composition contains, according to one embodiment, a mass proportion of said block copolymer of between 1.5 and 6%, preferably equal to between 2 and 5% (inclusive). According to another aspect, the invention relates to the use of said composition comprising a fluoropolymer grafted with maleic acid anhydride functional groups and at least one block copolymer comprising at least one hydrophobic block and at least one hydrophilic block, for to limit the bacterial proliferation on a surface in an aqueous medium. It is the merit of the Applicant that having demonstrated that the presence of a block copolymer comprising at least one hydrophobic block and at least one hydrophilic block, in addition to that of a fluoropolymer grafted with functions maleic acid anhydride, further reduces the adhesion of the biofilm to a surface thus covered, which makes it easier to clean. Its duration of use is thus increased. According to another aspect, the invention relates to a hollow body capable of allowing the storage or transport of water, especially drinking water, comprising at least one inner layer and a second layer which surrounds said inner layer and which is integral with the latter. said inner layer being adapted to come into contact with water. Typically, according to the invention, the inner layer consists of the composition having antibacterial properties described above. This inner layer which strongly limits the formation of a biofilm when it comes into contact with drinking water, is resistant to chlorinated water and does not allow the formed biofilm to attach itself permanently to its surface.

According to the invention, the inner layer can be covered directly or via a layer of binder by the second layer. Other layers may also space the inner layer of the second layer while solidifying them to one another. One or more layers may also cover the second layer to form the outer surface of the hollow body. The second layer may also form the outer surface of the hollow body.

Preferably, said second layer comprises at least one thermoplastic polymer selected from the list: a polyamide (for example PA 6, 11, 12, 6, 6, ...); An acrylic polymer, in particular a homo- or copolymeric PMMA comprising more than 50% by weight of methyl methacrylate (MMA); • a polyolefin (PE, PP, EPDM); • polyvinyl chloride (PVC); • chlorinated PVC (C-PVC); • polyethylene terephthalate (PET); • EVOH (ethylene-ethylene-vinyl alcohol copolymer); • polyetherketone (PEEK); • polyoxymethylene (acetal); • polyethersulfone; • polyurethane; A fluorinated polymer such as, for example, a PVDF, a polyvinyl fluoride, a TFE-ethylene copolymer (ETFE), a TFE-HFP copolymer (FEP), a TFE-ethylene-HFP copolymer (EFEP), a TFE-HFP copolymer -VDF (THV) or PTFE.

The shape and size of the hollow body of the invention are limited. It can be chosen from the pipes; composite tubes comprising a metal tube, in particular made of cast iron, covered with at least said inner layer and the second polymer layer; the pipes comprising the tubes and / or pipes and tanks, such as cans, barrels or water bottles, for example.

Thus, the hollow body of the present invention may be a cast iron tube whose inner surface is covered with the aforementioned inner layer. The outside of the cast tube can also be covered with another layer of polymeric material, applied for example, by dusting.

The present invention also relates to a method of manufacturing a hollow body such as that described above, able to contain water, especially potable water, according to which coextrudes an inner layer coming into contact with water, and at least one second outer layer which is disposed around said inner layer and integral with said inner layer, said inner layer consisting of the composition according to the invention comprising a fluoropolymer grafted with maleic anhydride functions and at least one block copolymer comprising at least one hydrophobic block and at least one hydrophilic block.

DEFINITIONS

Throughout this application, the term "pipe" refers to a substantially tubular member having one or two open ends along its longitudinal dimension which comprises one or more polymeric materials forming successive layers and no metal layer. The hose can be flexible or rigid. The section of the pipe is not limited according to the invention.

The term "composite tube" refers to a metal tube including cast iron whose inner surface is covered with an inner layer and whose outer surface may also be covered with a layer of polymeric material.

The term "pipe" refers to an assembly of several composite tubes and / or pipes.

The term "polymer" refers to homopolymers, copolymers, grafted or not, and block polymers.

The term "polymeric material" denotes a mixture containing at least one polymer and in particular a mixture of at least two polymers.

The term "cleansed" and all associated terms refers to the removal of the bacterial film that may form over a period of time on the inner surface of the hollow body. For the purposes of the present invention, "cleaning" comprises a step of chlorination with a chlorinated aqueous solution which is preceded by a hydromechanical takeoff step of the biofilm obtained at 5 weeks. Cleaning more or less easy is linked to the attachment of the biofilm on the inner surface of the hollow body.

By "antibacterial activity" is meant the property which consists in limiting the adhesion and / or the bacterial proliferation on a support, or even more generally the attachment and / or the proliferation of microorganisms such as, for example, fungi, yeast or viruses.

FIGURES

The present invention, its characteristics and the various advantages it affords will become more apparent on reading the examples which follow and which refer to the appended drawings in which: FIG. 1 represents the number of bacterial cells per cm 2 of area on the surface of different films which have been maintained for 24 hours in drinking water at 20 ° C; FIG. 2 represents the number of bacterial cells per cm 2 surface area on the surface of different films which have been maintained for 72 hours in drinking water at 20 ° C; and - FIG. 3 represents the number of bacterial cells per cm 2 surface area on the surface of different films which have been maintained for 5 weeks in drinking water at 20 ° C. and then cleaned according to the protocol described below.

EXAMPLES

Two 300 μm thick films were made by Haake® 1 contra-rotating twin-screw extrusion from the following compositions:

Composition 1: Vinylidene fluoride homopolymer grafted by irradiation with maleic acid anhydride groups, comprising 0.6% by weight of maleic anhydride.

Composition 2: homopolymer of vinylidene fluoride of the composition 1 mixed with 2% by weight of a block copolymer comprising a hydrophilic block (25% by weight) formed of a BA / HEMA copolymer (mass ratio 80/20), molar mass by number: Mn = 9000 g / mol and a hydrophobic block (75% by weight) formed of a terpolymer MMA / BA / HEMA, (68% / 25.5% / 6.5% by weight); molar mass in number of the block copolymer: Mn = 23000 g / mol.

Composition 3: the same as for composition 2 except that it comprises 5% by weight of the block copolymer.

The antibacterial performance of these films was then evaluated.

Evaluation of the antibacterial performances The evaluation of the bacterial performances is carried out according to the following protocol: Step 1: cleaning of the materials thanks to a solution of sodium dodecyl sulphate (SDS) at 40 ° C (0.1% by weight) then washing by immersion in an aqueous solution of 0.1M HCl at 40 ° C.

Step 2: colonization of the materials in a reactor in which drinking water circulates at a flow rate of 69 ml / h at 20 ° C. The residence time of the water in the reactor is 12 hours. The samples are exposed to light.

Step 3: Labeling of the bacteria with a dye (SYBR® green II RNA gel stain 10,000X concentrated in DMSO and marketed by the company Thermo Fisher

Scientific), then counting by a fluorescence microscope. For each material, a reading of 100 × 100 μm fields is carried out.

The results after 24 hours of colonization are visible in FIG. 1 while the results after 72 hours of colonization are visible in FIG. 2.

In Figs. 1, 2 and 3, With reference to a polyethylene film, PU refers to a polyurethane film, G3-1 refers to a film corresponding to the first composition, G3-2 corresponds to a film of composition 2 and G3 -3 to a composition film 3.

It can be seen from Figs. 1 and 2, that the amount of bacteria that was deposited after immersion of the film in drinking water at 20 ° C for 24 hours or 72 hours is less in the case of G3-1 to G3-3 films. Indeed, for the material DU after 24H, the number of bacteria cells per cm2 is 6000 and 18300 after 72 hours. For the films of composition 1 to 3, it is less than 170 cells of bacteria per cm 2 whatever the formulation after 72 hours. With regard to the grafted PVDF, its antibacterial properties are clearly noted because the number of bacterial cells per cm 2 is equal to 298 after 24 hours and <170 after 72 hours.

The compositions with reference to the invention thus avoid bacterial colonization; this antibacterial effect is more marked when the film contains a block copolymer as defined with reference to compositions 2 and 3 after 24 hours of colonization. After 72h, the values are below the detection limit (<1.7x102 cells / cm2)

Evaluation of the ease of cleaning The evaluation of the cleaning facility is implemented according to the following protocol:

Samples that have been colonized for 5 weeks in drinking water are used. Step 1: Hydrodynamic cleaning by increasing shear stress from 1 Pa to 5 Pa for 30 min.

Water temperature: 20 ° C ± 1 ° C.

Step 2: Hydrodynamic cleaning with a chlorinated aqueous solution containing 50 mg Ch / L at a shear stress of 1 Pa.

Step 3: stalling of the bacteria on the surface of the material by ultrasound then counting of the remaining bacteria by optical microscopy with labeling of the bacteria with a dye (SYBR® green II RNA gel stain 10,000X concentrated in DMSO and marketed by the company Thermo Fisher Scientific ).

For each material, a reading of 100 x 100 μm fields is performed.

The results are visible in FIG. 3. It is found that the bacterial film has been completely removed on the composition film 3. On the film DU, there remains 53000 bacteria / cm 2 whereas for the film of composition 1, the number of bacteria / cm 2 is 1000. For the film of composition 2, the film has been virtually eliminated and in any case, eliminated more effectively than on the film of polyethylene material. Again, the presence of the block copolymer improves the results.

Claims (15)

1. Composition comprising a fluoropolymer grafted with maleic acid anhydride functional groups and at least one block copolymer comprising at least one hydrophobic block and at least one hydrophilic block. 2. Composition according to claim 1, in which the said fluoropolymer is chosen from: homo-and copolymers of vinylidene fluoride (VDF) preferably containing at least 50% by weight of VDF, the copolymer being chosen from chlorotrifluoroethylene ( CTFE), hexafluoropropylene (HFP), trifluoroethylene (VF3) and tetrafluoroethylene (TFE), homo-and copolymers of trifluoroethylene (VF3), copolymers, and especially terpolymers, combining the residues of chlorotrifluoroethylene units (CTFE ), tetrafluoroethylene (TFE), hexafluoropropylene (HFP) and / or ethylene and optionally VDF and / or VF3 units. 3. Composition according to one of claims 1 or 2, wherein said fluoropolymer is a polyvinylidene fluoride (PVDF) homopolymer or copolymer containing by weight, at least 50% of VDF, more preferably at least 75% and better still at least 85%. 4. A composition according to any one of the preceding claims, wherein the content of maleic anhydride in the grafted fluoropolymer ranges from 0.2 to 1.0%, and preferably from 0.4 to 0.7%. % by weight relative to the total weight of the fluoropolymer. 5. A composition according to any one of the preceding claims, wherein the block copolymer comprises at least one hydrophilic block obtainable from monomers of n-butyl acrylate and hydroxyethyl methacrylate, and at least a hydrophobic block obtainable from a methyl methacrylate monomer. 6. Composition according to claim 5, wherein the hydrophilic block is composed of a random copolymer containing, by weight, between 99 and 50%, preferably between 95 and 70% of n-butyl acrylate monomers and between 1 and 50%, preferably between 5 and 30%, of hydroxyethyl methacrylate monomers. 7. Composition according to one of claims 5 or 6, wherein the hydrophobic block is composed of at least 50% of polymethyl methacrylate, the remainder being formed of a mixture of methacrylate monomers or acrylates, preferably monomers of n-butyl acrylate and hydroxyethyl methacrylate. 8. Composition according to one of the preceding claims, which contains a mass proportion of said block copolymer between 1.5 and 6%, preferably equal to between 2 and 5%. 9. Use of a composition according to any one of claims 1 to 8 for limiting the bacterial proliferation on a surface in an aqueous medium. Hollow body for storing or transporting water, especially drinking water, comprising at least one inner layer in contact with water and a second layer which surrounds and is integral with said inner layer, said inner layer being composed of the composition according to one of claims 1 to 8. 11. hollow body according to claim 10 wherein said second layer comprises at least one thermoplastic polymer selected from the list: a polyamide (for example PA 6, 11, 12, 6,6, ...); An acrylic polymer, in particular a homo- or copolymeric PMMA comprising more than 50% by weight of methyl methacrylate (MMA); • a polyolefin (PE, PP, EPDM); • polyvinyl chloride (PVC); • chlorinated PVC (C-PVC); • polyethylene terephthalate (PET); • EVOH (ethylene-ethylene-vinyl alcohol copolymer); • polyetherketone (PEEK); • polyoxymethylene (acetal); • polyethersulfone; • polyurethane; A fluorinated polymer such as, for example, a PVDF, a polyvinyl fluoride, a TFE-ethylene copolymer (ETFE), a TFE-HFP copolymer (FEP), a TFE-ethylene-HFP copolymer (EFEP), a TFE-HFP copolymer -VDF (THV) or PTFE. 12. hollow body according to one of claims 10 or 11 selected from the pipes; composite tubes comprising a metal tube, in particular made of cast iron, covered with at least said inner layer and the second polymer layer; pipes comprising the aforesaid tubes and / or pipes and tanks, such as cans, barrels or flasks. 13. The method of manufacturing the hollow body according to one of claims 10 to 12, wherein said inner layer is coextruded and at least a second outer layer which is disposed around said inner layer and secured to said inner layer. 14. Use of a fluoropolymer grafted with maleic anhydride functions, to limit bacterial adhesion and / or proliferation on a surface in an aqueous medium. 15. The use according to claim 14, wherein said grafted fluoropolymer is a homopolymer of vinylidene fluoride which comprises, by weight, from 0.2 to 1.0%, and preferably from 0.4% to 0.7%, of maleic anhydride.