EP3041898A1

EP3041898A1 - Thermoplastic fluorinated polymer composition for off-shore pipes

Info

Publication number: EP3041898A1
Application number: EP14786989.5A
Authority: EP
Inventors: Anthony Bonnet; Cyrille Mathieu; Barbara Ramfel; Alejandra REYNA-VALENCIA
Original assignee: Arkema France SA
Current assignee: Arkema France SA
Priority date: 2013-09-02
Filing date: 2014-09-01
Publication date: 2016-07-13
Also published as: US20160215134A1; FR3010089B1; CN105705576A; FR3010089A1; WO2015028761A1

Abstract

The invention relates to a composition comprising: - 60 to 80 wt % of a vinylidene polyfluoride; - 10 to 30 wt % of a copolymer of vinylidene fluoride and a comonomer; - a plasticizer; and - 3 to 20 wt % of fibers. Also disclosed is the use of said composition for the production of various items such as pipes.

Description

COMPOSITION OF THERMOPLASTIC FLUORINE POLYMERS FOR OFF-SHORE TUBES

FIELD OF THE INVENTION

The present invention relates to a thermoplastic fluoropolymer composition, processes for the manufacture thereof, as well as products that can be made from this composition, in particular the polymeric sheaths of flexible hoses used for transporting fluids from petroleum -marine, or "off-shore", and land, or "onshore") or gas.

TECHNICAL BACKGROUND

The transport of chemicals in the liquid or gaseous state in pipes has many advantages: it is more economical once the infrastructure is in place; it allows the transport of large volumes; it ensures a great security of supply, thanks to a regular flow; finally, it is safer than rail or road.

It is known to use, for the transport of liquid or gaseous products, metal or plastic tubes, or metal tubes coated with one or more polymeric layers. Depending on the fluid to be transported, these tubes must meet multiple requirements, particularly with regard to the properties of mechanical resistance (in particular to impact), elasticity, creep resistance, fatigue resistance, resistance to swelling, chemical resistance (to corrosion, oxidation, ozone, chlorinated products ...) and thermal resistance.

For example, pipes with one or more metal elements guaranteeing the mechanical rigidity but not sealed to transported fluids (for example steel or cast iron elements), as well as various layers based on polymeric compositions, are known for sealing transported fluids as well as thermal insulation. Typically, in the case of polymeric layers, the thickness / diameter ratio is of the order of 1/10. These polymeric compositions can be polyethylene-based, but this limits the temperature of use of the pipes to 60 ° C maximum. They may also be based on fluorinated polymers such as polyvinylidene fluoride also called polyvinylidene fluoride (PVDF), suitable for higher use temperatures, up to 130 ° C, and having good chemical resistance and good thermal resistance. However, PVDF is very rigid, and for this reason PVDF homopolymers are often formulated or used in admixture with vinylidene fluoride (VDF) copolymers and possibly plasticizer in order to reduce their rigidity.

Flexible hoses are also used for the transport of oil or natural gas extracted from submarine or terrestrial deposits. These pipes are formed of multilayer structures including polymeric sheaths and reinforcing layers of metal or composite materials.

Flexible hoses include, from the inside to the outside:

at least one internal sealing tube in contact with the transported fluid, consisting of a polymeric material,

one or more reinforcement layers surrounding said internal sealing tube, and

- an external protective sheath.

BE 832851 discloses fluorinated elastomers comprising a molar proportion of 50 to 85% of VDF and 15 to 25% of hexafluoropropylene (HFP), ie a mass proportion of 47 to 71% of VDF and 29 to 53% of HFP, which are used for the manufacture of PVDF molded bodies comprising from 1 to 30% by weight of fluoroelastomer. Such compositions, however, have limited extrudability, and do not allow the manufacture of tubes having a thickness / diameter ratio close to 1/10. In addition, such compositions exhibit insufficient fatigue strength for the applications described above.

EP 1342752 discloses PVDF-based compositions comprising: (A) a PVDF homopolymer or a VDF-based copolymer; (B) a fluoroelastomer; (C) optionally a plasticizer. The fluorinated elastomer (B) is present in an amount of from 0.5 to 10 parts by weight per 100 parts of homopolymer or copolymer (A) and from 0 to 10 parts by weight of a plasticizer (C) with the condition further that the sum of (B) plus (C) is from 0.5 to 10.5 parts by weight. These compositions correspond to the following mass proportions: 89.5 to 90.5% of a PVDF homopolymer or a VDF-based copolymer (A); 0.5 to 9% of a fluoroelastomer (B); 0 to 9% of a plasticizer (C). Among the examples are disclosed compositions comprising 2 to 4% VDF / HFP copolymer as a fluorinated elastomer. The level of HFP in the copolymer is 30 to 40%.

EP 0608639 discloses polymeric compositions comprising, by weight, 60 to 80% of PVDF, 20 to 40% of a thermoplastic copolymer of VDF and another fluorinated comonomer (present in amounts of 5 to 25% in the copolymer), and from 5 to 20% of a plasticizer (relative to the sum of the PVDF and the copolymer). Among the thermoplastic copolymers envisaged include VDF / HFP copolymers. The HFP contents indicated in the copolymers which are disclosed in the examples are of the order of 10%.

EP 0608940 discloses polymeric compositions comprising, by weight, 25 to 75% of PVDF and 25 to 75% of thermoplastic copolymer of VDF and of another fluorinated comonomer (present in amounts of 5 to 25% in the copolymer ). Among the thermoplastic copolymers envisaged include VDF / HFP copolymers.

WO 2006/045753 describes polymeric compositions based on PVDF and a thermoplastic fluorinated copolymer having an apparent melt viscosity of less than or equal to 60,000 Pa.s at a speed gradient of 1 sec ^-1 . The thermoplastic fluorinated copolymer may be, for example, a copolymer of VDF and another fluorinated comonomer, which may be present in a content of 5 to 25%. A mixture of PVDF homopolymer and fluorinated copolymer has an average intrinsic viscosity of less than 2 dl / g.

However, the polymeric compositions proposed in the state of the art are not completely satisfactory. In particular, the resistance to fatigue and / or temperature resistance and creep resistance of the pipes made from the polymeric compositions of the state of the art are considered insufficient for the intended applications, and particularly for the manufacture of pipes for the transport of fluids for submarine and ground oil exploitation, as well as for the transport of liquid or gaseous synthesis products (for example for the transport of hydrogen).

There is still a need to provide fluorinated thermoplastic polymer compositions having reduced creep at high temperature associated with good cold fatigue performance. There is also still a need to provide fluorinated thermoplastic polymer compositions having improved properties for the manufacture of umbilicals and flexible tubes used in particular off-shore.

SUMMARY OF THE INVENTION

The invention firstly relates to a composition comprising:

from 60 to 80% by weight of a polyvinylidene fluoride;

from 10 to 30% by weight of a copolymer of vinylidene fluoride and a comonomer;

a plasticizer, and

from 3 to 20% by weight of fibers.

Advantageously, the intrinsic viscosity of the PVDF homopolymer and fluorinated copolymer mixture is greater than 2 dl / g.

According to one embodiment, the plasticizer is chosen from dibutyl sebacate, dioctyl phthalate, N-n-butylsulfonamide, polymeric polyesters and combinations thereof, and is preferably dibutyl sebacate.

According to one embodiment, the plasticizer is present in the composition in a mass proportion of 1 to 5%, preferably of 1.5 to 3.5%, advantageously of 1.5 to 2.5%.

According to one embodiment:

the mass proportion of polyvinylidene fluoride is from 65 to 75%; and or

the mass proportion of the copolymer is from 10 to 30%, preferably from 15 to 25%; and or

- The mass proportion of fibers is 5 to 15%.

According to one embodiment, the mass proportion of (co) monomer (s) other than vinylidene fluoride in the copolymer is in the range 15 to 24%, preferably 19 to 24% inclusive.

The intrinsic viscosity of the blend of the polyvinylidene fluoride homopolymer and said vinylidene fluoride copolymer, in the absence of plasticizer, was found to be greater than 2dl / g, when measured in DMF (dimethylformamide) stabilized with 0.1M LiBr at 25 ° C and 4 g / l.

According to one embodiment, the melt apparent viscosity of the composition according to the invention is greater than 60000 Pa.s at a rate gradient of 1 sec ^-1 . Surprisingly it has been found that the composition according to the invention the invention is particularly suitable for being implemented by extrusion or coextrusion, and this contrary to what was found in the document WO 2006/045753 raised (page 4, 1. 5-8).

According to one embodiment, the fluorinated comonomer is chosen from vinyl fluoride, trifluoroethylene, chlorotrifluoroethylene (CTFE), 1,2-difluoroethylene, tetrafluoroethylene (TFE), hexafluoropropylene (HFP) and perfluoro (vinyl alkyl). ethers such as perfluoro (methylvinyl) ether (PMVE), perfluoro (ethylvinyl) ether (PEVE), perfluoro (propylvinyl) ether (PPVE), perfluoro (1,3-dioxozole); perfluoro (2,2-dimethyl-1,310xioxole) (PDD), the product of formula CF2 = CFOCF2CF (CF3) OCF2CF2X wherein X is SO ₂ F, CO ₂ H, CH ₂ OH; CH ₂ OCN or CH ₂ OPO ₃ H, the product of formula CF 2 = CFOCF 2 CF 2 SO 2 F; the product of formula F (CF 2) nCH 2 OCF = CF 2 in which n is 1, 2,3,4 or 5, the product of formula R 1 CH 2 OCF = 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 R3OCF = CH2 in which R3 is F (CF2) z and z is 1, 2, 3, or 4 or alternatively perfluorobutylethylene (PFBE), fluoroethylenepropylene (FEP), 3,3,3-trifluoropropene, 2-trifluoromethyl-3,3,3-trifluoro-1-propene, 2,3,3,3-tetrafluoropropene or HFO-1234yf, E-1, 3,3,3-tetrafluoropropene or HFO-1234zeE, Z 1, 3,3,3-tetrafluoropropene or HFO-1234zeZ, 1,1,2,3-tetrafluoropropene or HFO-1234yc, Ie, 2,3,3-tetrafluoropropene or HFO-1234ye, 1, 1, 3 , 3-tetrafluoropropene or HFO-1234zc and chlorotetrafluoropropene or HCFO-1224.

According to a preferred embodiment, the comonomer is hexafluoropropylene

According to one embodiment, the copolymer is a terpolymer. According to one embodiment, the fibers are chosen from carbon fibers, glass fibers, carbon nanotubes, carbon nanofibers, synthetic fibers and combinations thereof.

According to one embodiment, the fibers are crosslinked polyvinylidene fluoride fibers.

According to one embodiment, the above composition consists of the homopolymer of polyvinylidene fluoride, the copolymer of vinylidene fluoride and at least one other fluorinated comonomer copolymerizable with the VDF, the plasticizer and the fibers.

According to a preferred embodiment, which will be described in more detail below, the above composition consists of polyvinylidene fluoride homopolymer, VDF / HFP copolymer, plasticizer and carbon fibers.

The invention also relates to a method for producing a composition as described above, comprising the mixture of polyvinylidene fluoride, copolymer, fibers and plasticizer.

More particularly, the composition according to the invention is prepared by melt blending all the constituents, on a compounding tool such as a twin-screw extruder, a co-kneader or an internal or cylinder mixer.

According to one embodiment, the homopolymer and the copolymer are in dry form during mixing, preferably in the form of powders, and preferably the mixture with the plasticizer and the fibers is carried out in the molten state on a compounding tool as a twin-screw extruder, co-kneader or internal or cylinder mixer.

According to one embodiment, the above method comprises mixing the homopolymer and the latex copolymer, drying the homopolymer and copolymer mixture, and combining the dried blend with the plasticizer and the fibers, is carried out in the molten state on a compounding tool such as a twin-screw extruder, a comalizer or an internal or cylinder mixer.

The composition according to the invention obtained by the manufacturing method described above can then be transformed for use. in the form of pipes, cables, especially using tools such as an extruder provided with a suitable die or for use as binders of conductive particles.

The subject of the invention is also, in general, a tube comprising at least one layer consisting of the composition according to the invention.

According to one embodiment, said tube is intended to be used as a polymeric sheath of flexible hoses used for transporting fluids from oil and gas operations. In this form, it can be used, in combination with at least one reinforcing layer and an outer protective sheath, as a flexible hose for transporting fluids from oil or gas operations.

According to one embodiment, said tube is a land transport pipe of products in the gaseous state.

According to one embodiment, the aforementioned pipe is for the transport of synthetic products, in particular for the transport of hydrogen, oxygen, water vapor, carbon monoxide, ammonia, hydrogen fluoride , hydrochloric acid, hydrogen sulfide, any gas from the cracking of hydrocarbons, or mixtures thereof.

According to one embodiment, said tube is intended for the terrestrial transport of products in the liquid state, for example the transport of water, solvents or mixtures thereof.

According to one embodiment, the aforementioned pipe is a service station underground pipe or a vehicle fuel supply pipe.

The invention also relates to an electric cable made from the above-mentioned composition.

The invention also relates to a binder of conductive particles for a rechargeable battery, manufactured from the aforementioned composition.

The invention also relates to the use of the composition described above, for the manufacture of pipes, electrical cables or conductive particles binders mentioned above. The present invention overcomes the disadvantages of the state of the art. It provides more particularly fluorinated thermoplastic polymer compositions having reduced creep at high temperature and / or better resistance to cold fatigue.

It also provides fluorinated thermoplastic polymer compositions having improved properties for the manufacture of umbilicals and flexible tubes used in particular off-shore.

This is accomplished through the combination of a polyvinylidene fluoride, polyvinylidene fluoride copolymer, fibers and plasticizer in specific ranges.

In particular, the presence of fibers makes it possible to improve creep resistance at temperatures of up to 160 or 165 ° C combined with good resistance to cold fatigue (fatigue at a temperature below 0 ° C.), which is provided mainly by the copolymer.

DESCRIPTION OF EMBODIMENTS OF THE INVENTION

The invention is now described in more detail and without limitation in the description which follows.

Unless otherwise stated, all the percentages indicated correspond to mass proportions.

The PVDF polymer used in the context of the invention preferably has a melt flow index of less than or equal to 15 g / 10 min, advantageously less than or equal to 10 g / 10 min, and ideally less than or equal to 5 g / 10 min, according to ISO 1133 (230 ° C, 12.5 kg), to ensure good mechanical strength properties.

The mass proportion of this PVDF present in the composition may be for example 60 to 62%; or from 62 to 64%; or from 64 to 66%; or from 66 to 68%; or from 68 to 70%; or from 70 to 72%; or from 72 to 74%; or 74 to 76%; or from 76 to 78%; or 78 to 80%.

The copolymer used in the context of the invention is a copolymer of vinylidene fluoride and a comonomer. Preferably it is a fluorinated monomer.

Combinations of several comonomers can be used. For example, if two different comonomers are used, the copolymer is actually a terpolymer (the mass proportion of comonomer mentioned in the demand then understood as representing the mass proportion of the sum of the comonomers).

Preferably only one comonomer is present in the copolymer. Moreover, it is also possible to use a mixture of two or more of the above copolymers, for example a mixture of

P (VDF-HFP) and P (VDF-CTFE). In such a case, all the indications relating to the proportion of copolymer in the composition are read as referring to the proportion of all the copolymers in the composition.

It is however preferred that only one copolymer be present.

According to one embodiment, the comonomer is chosen from HFP, CTFE, CFE, TFE and TrFE.

Preferably this is the HFP: it is this example which is retained for the following description, it being understood that it is analogous when the HFP is replaced by another comonomer.

The copolymer P (VDF-HFP) is obtained by copolymerization of VDF monomers and HFP monomers.

In the context of the invention, the level or mass proportion of fluorinated (co) monomers is less than 25%. According to some embodiments, this mass proportion of fluorinated (co) monomer is between 15 and 24% by weight, preferably between 19 and 24%.

The proportion by weight of fluorinated comonomer in the copolymer is preferably determined by nuclear magnetic resonance. In particular, the following ¹⁹ F NMR method developed for a VDF / HFP copolymer can be used. The copolymer samples are dissolved in a 5 mm diameter NMR tube. Copolymer samples containing more than 10% by weight of HFP are dissolved in d6 acetone at 55 ° C. An amount of copolymer (about 10 mg) is placed in a tube and solvent is added to fill 5.5 cm of tube (about 0.75 ml of solvent). A heating block is used to bring the samples to the desired temperature. The samples are heated for at least one hour until dissolution of the solid and disappearance of the gel. The tubes are returned to check for frost. The spectra are acquired on a Bruker DMX or Varian Mercury 300 spectrometer operated at 55 ° C in the case of the solvent acetone-d6 and are analyzed according to the method described in "Composition and sequence distribution of vinylidene fluoride copolymer and terpolymer fluoroelastomers. Determination by 19F NMR spectroscopy and correlation with some properties ". M. Pianca et al, Polymer, 1987, vol.28, 224-230. Accuracy of measurements is verified by measuring the integrals of CF ₃ and CF and comparing them to see if they are in a 3: 1 ratio.

Preferably, the copolymer used for the preparation of the composition according to the invention is essentially free of homopolymer.

The copolymer can be manufactured by the method described in the publication by M. Pianca et al supra.

Plasticizers within the meaning of the invention are the compounds defined in the Encyclopedia of Polymer Science and Engineering, edited by Wiley & Sons (1989), p.568-569 and p.588-593. They can be monomeric or polymeric. Mention may in particular be made of dibutyl sebacate, dioctyl phthalate, N-n-butylsulfonamide, polymeric polyesters and combinations thereof. Suitable polymeric polyesters include those derived from adipic, azelaic or sebacic acids and diols, and combinations thereof, the molecular weight being preferably greater than or equal to 1500, more preferably greater than or equal to 1800, and preferably less than or equal to 5000, and more particularly less than or equal to 2500. Plasticizers of excessive molecular mass would result in a composition having an impact resistance too low.

Dibutyl sebacate is a particularly advantageous plasticizer.

The presence of the plasticizer facilitates the manufacture of the composition according to the invention or its transformation to produce products or various objects. It also improves the impact resistance of the composition according to the invention.

Preferably, the copolymer used for the preparation of the composition according to the invention is essentially free of homopolymer. The copolymer may in particular be manufactured according to the method described in patent EP 1 144469 B1.

The mass proportion of the above copolymer (and especially P (VDF-HFP)) in the composition may be, for example, from 10 to 12%; or from 12 to 14%; or from 14 to 16%; or from 16 to 18%; or 18 to 20%; or 20 to 22%; or 22 to 24%; or 24 to 26%; or from 26 to 28%; or 28 to 30%.

As a plasticizer, it is also possible to use PVDF or a copolymer derived from PVDF (for example P (VDF-HFP)) having a viscosity lower than the PVDF and P (VDF-HFP) described above, which represent the two main constituents of the composition. This PVDF or plasticizer copolymer may thus have a viscosity under 100 s ^-1 and at a temperature of 230 ° C. which is lower than the viscosity of the majority PVDF by a factor of at least 5, or at least equal to 10, or at least equal to 20, or at least equal to 30. For example, this PVDF or plasticizer copolymer may have a viscosity of 50 to 300 Pa.s at 100 s ^-1 and at a temperature of 230 ° C.

The composition according to the invention also comprises fibers.

The term "fibers" refers to structures of elongated shape, or filamentary type. The fibers have a length in a longitudinal direction (corresponding to the maximum dimension of the structure) and a diameter (defined as the maximum dimension of the structure perpendicular to the longitudinal direction), the length being greater than the diameter of at least one factor. 10, preferably at least 50 or at least 100.

In particular, it is possible to use polymeric fibers, for example stretched polymer fibers. It is thus possible to use polyamide fibers such as polyamide 6 (PA-6), polyamide 11 (PA-11), polyamide 12 (PA-12), polyamide 6.6 (PA-6.6), polyamide 4.6 (PA-4.6), polyamide 6.10 (PA-6.10) or polyamide 6.12 (PA-6.12), polyamide / polyether block copolymer (marketed under the name Pebax®), high-density polyethylene, polypropylene or polyester for example polyhydroxyalkanoates and polyesters (marketed by DuPont under the trade name Hytrel®.

Other possible polymeric fibers are crosslinked PVDF fibers. These can be obtained by extrusion of PVDF and then irradiation to cause the crosslinking. We can add an agent crosslinking to facilitate crosslinking, such as aromatic or non-aromatic bisimide or else triallyl cyanurate or triallyl isocyanurate.

The use of crosslinked PVDF fibers has the advantage of good compatibility between the fibers and the polymer matrix. In this way, a good adhesion of the fibers in the matrix is obtained, a degradation of the matrix by the fibers is avoided, and a weight gain is realized with respect to glass fibers for example.

Carbon fibers can also be used.

It is also possible to use glass fibers, in particular of the E, R or S2 type.

It is also possible to use aramid fibers (trade name Kevlar®).

It is also possible to use boron fibers.

It is also possible to use silica fibers.

Natural fibers such as flax, hemp or sisal can also be used.

For all of the fibers above, the average diameter is advantageously from 2 to 100 μm, preferably from 10 to 20 μm, and the average length is advantageously from 0.5 to 10 mm, preferably from 2 to 4 mm. . These are averages in number, on all the fibers.

It is also possible to use carbon nanotubes as fibers.

Carbon nanotubes are hollow tubular structures having a graphitic plane disposed about a longitudinal axis or several graphitic planes (or sheets) arranged concentrically about a longitudinal axis.

The carbon nanotubes may be of the single-walled, double-walled or multi-walled type. The double-walled nanotubes may in particular be prepared as described by Flahaut et al in Chem. Corn. (2003), p.1442. The multi-walled nanotubes may be prepared as described in WO 03/02456.

The carbon nanotubes generally have a mean diameter (perpendicular to the longitudinal axis, the average value being a linear average along the longitudinal and statistical axis on a set of nanotubes) ranging from 0.4 to 100 nm, preferably from 1 to 50 nm and better still from 2 to 30 nm, indeed from 10 to 15 nm, and advantageously from 0.1 to 10 μm. The length / diameter ratio is preferably greater than 10 and most often greater than 100. Their specific surface area is, for example, from 100 to 300 m ² / g, advantageously from 200 to 300 m ² / g, and their density. Apparent may in particular be from 0.05 to 0.5 g / cm ³ and more preferably from 0.1 to 0.2 g / cm ³ . The multiwall nanotubes may for example comprise from 5 to 15 sheets (or walls) and more preferably from 7 to 10 sheets. These nanotubes can be treated or not.

The dimensions and in particular the average diameter of the carbon nanotubes can be determined by transmission electron microscopy.

An example of raw carbon nanotubes is in particular marketed by Arkema under the trade name Graphistrength® ^® C100.

These carbon nanotubes may be purified and / or treated (for example oxidized) and / or milled and / or functionalized before being used in the context of the invention.

The grinding of the carbon nanotubes may in particular be carried out cold or hot and be carried out according to the known techniques used in devices such as ball mills, hammers, grinders, knives, jet gasses or any other grinding system capable of reducing the size of the entangled network of nanotubes. It is preferred that this grinding step is performed according to a gas jet grinding technique and in particular in an air jet mill.

The purification of the raw or milled carbon nanotubes can be carried out by washing with a sulfuric acid solution, so as to rid them of any residual mineral and metal impurities, such as iron, originating from their process of preparation. The weight ratio of nanotubes to sulfuric acid may in particular be from 1: 2 to 1: 3. The purification operation may also be carried out at a temperature ranging from 90 to 120 ° C, for example for a period of 5 to 10 hours. This operation can advantageously be followed by steps of rinsing with water and drying of the purified carbon nanotubes. Carbon nanotubes may alternatively be purified by high temperature heat treatment, typically above 1000 ° C.

The oxidation of the carbon nanotubes is advantageously carried out by putting them in contact with a solution of sodium hypochlorite containing from 0.5 to 15% by weight of NaOCI and preferably from 1 to 10% by weight of NaOCI, for example in a weight ratio of carbon nanotubes to sodium hypochlorite ranging from 1: 0.1 to 1: 1. The oxidation is advantageously carried out at a temperature below 60 ° C. and preferably at room temperature, for a duration ranging from a few minutes to 24 hours. This oxidation operation may advantageously be followed by filtration and / or centrifugation, washing and drying steps of the oxidized nanotubes.

The operation of carbon nanotubes can be carried out by grafting reactive units such as vinyl monomers on their surface. The material constituting the carbon nanotubes is used as a radical polymerization initiator after having been subjected to a heat treatment at more than 900 ° C., in an anhydrous and oxygen-free medium, which is intended to eliminate the oxygenated groups from its surface. It is thus possible to polymerize methyl methacrylate or hydroxyethyl methacrylate on the surface of carbon nanotubes in order to facilitate in particular their dispersion in the polyamides.

In the present invention, it is preferable to use optionally milled raw carbon nanotubes, ie carbon nanotubes which are neither oxidized nor purified nor functionalized and have undergone no other chemical and / or thermal treatment.

It is also possible to use carbon nanofibers as fibers. Carbon nanofibers are filament-shaped objects. Unlike carbon nanotubes, these are not hollow objects. By way of example, the carbon nanofibers may have a so-called "herringbone" structure (stack of graphene layers oriented symmetrically on either side of the longitudinal axis); or a platelet or lamellar structure (graphene sheets piled perpendicular to the axis); or a conical structure, still called "stacked cup" (continuous sheet of graphene wound on itself); or a so-called bamboo structure (fiber having periodic variations in diameter, formed of compartments separated by a graphitic sheet); or a ribbon structure (graphene sheets oriented parallel to the longitudinal axis without being wound); or a tubular structure (similar to the structure of multiwall carbon nanotubes).

The carbon nanofibers may have a mean diameter (perpendicular to the longitudinal axis, the mean value being a linear average along the longitudinal and statistical axis over a set of nanofibers) ranging from 0.4 to 100 nm, preferably from 1 to 50 nm and better still from 2 to 30 nm, indeed from 10 to 15 nm, and advantageously from 0.1 to 10 μm. The length / diameter ratio is preferably greater than 10 and most often greater than 100. The dimensions and in particular the average diameter of the carbon nanofibers can be determined by scanning electron microscopy.

Mixtures of two or more of the above two types of fibers may also be used.

The proportion of fibers in the composition may be for example 3 to 4%; or 4 to 5%; or from 5 to 6%; or 6-7%; or 7 to 8%; or from 8 to 9%; or from 9 to 10%; or from 10 to 1 1%; or from 1 to 12%; or from 12 to 13%; or from 13 to 14%; or 14 to 15%; or 15 to 16%; or from 16 to 17%; or from 17 to 18%; or from 18 to 19%; or 19 to 20%.

According to one embodiment, the composition according to the invention consists of PVDF, P (VDF-HFP), plasticizer and fibers.

Alternatively, provision may be made to add one or more additives, in particular a manufacturing aid, such as a lubricant. Mention may in particular be made of stearates, such as calcium or zinc stearate, natural waxes and polytetrafluoroethylene and its derivatives. When a manufacturing adjuvant is present, it is typically included in a weight ratio of 0.01 to 0.3%, preferably 0.02 to 0.1%.

According to one embodiment, the composition according to the invention consists of PVDF, P (VDF-HFP), plasticizer, fibers and a manufacturing adjuvant.

Examples of formulations for the composition according to the invention are given in the table below (the amount of plasticizer and additives not being specified):

Proportion Proportion Proportion

Formulation N °

of PVDF P (VDF-HFP) of Fibers

1 60 to 64% 10 to 14% 3 to 5%

2 60 to 64% 10 to 14% 5 to 8%

3 60 to 64% 10 to 14% 8 to 12%

4 60 to 64% 10 to 14% 12 to 15%

5 60 to 64% 10 to 14% 15 to 20%

6 60 to 64% 14 to 18% 3 to 5%

7 60 to 64% 14 to 18% 5 to 8%

8 60 to 64% 14 to 18% 8 to 12%

9 60 to 64% 14 to 18% 12 to 15%

10 60 to 64% 14 to 18% 15 to 20%

1 1 60 to 64% 18 to 22% 3 to 5% Proportion Proportion Proportion

Formulation N °

of PVDF P (VDF-HFP) of Fibers

12 60 to 64% 18 to 22% 5 to 8%

13 60 to 64% 18 to 22% 8 to 12%

14 60 to 64% 18 to 22% 12 to 15%

15 60 to 64% 18 to 22% 15 to 20%

16 60 to 64% 22 to 26% 3 to 5%

17 60 to 64% 22 to 26% 5 to 8%

18 60 to 64% 22 to 26% 8 to 12%

19 60 to 64% 22 to 26% 12 to 15%

20 60 to 64% 26 to 30% 3 to 5%

21 60 to 64% 26 to 30% 5 to 8%

22 60 to 64% 26 to 30% 8 to 12%

23 64 to 68% 10 to 14% 3 to 5%

24 64 to 68% 10 to 14% 5 to 8%

25 64 to 68% 10 to 14% 8 to 12%

26 64 to 68% 10 to 14% 12 to 15%

27 64 to 68% 10 to 14% 15 to 20%

28 64 to 68% 14 to 18% 3 to 5%

29 64 to 68% 14 to 18% 5 to 8%

30 64 to 68% 14 to 18% 8 to 12%

31 64 to 68% 14 to 18% 12 to 15%

32 64 to 68% 14 to 18% 15 to 20%

33 64 to 68% 18 to 22% 3 to 5%

34 64 to 68% 18 to 22% 5 to 8%

35 64 to 68% 18 to 22% 8 to 12%

36 64 to 68% 18 to 22% 12 to 15%

37 64 to 68% 22 to 26% 3 to 5%

38 64 to 68% 22 to 26% 5 to 8%

39 64 to 68% 22 to 26% 8 to 12%

40 64 to 68% 26 to 30% 3 to 5%

41 64 to 68% 26 to 30% 5 to 8%

42 68 to 72% 10 to 14% 3 to 5%

43 68 to 72% 10 to 14% 5 to 8%

44 68 to 72% 10 to 14% 8 to 12%

45 68 to 72% 10 to 14% 12 to 15%

46 68 to 72% 10 to 14% 15 to 20% Proportion Proportion Proportion

Formulation N °

of PVDF P (VDF-HFP) of Fibers

47 68 to 72% 14 to 18% 3 to 5%

48 68 to 72% 14 to 18% 5 to 8%

49 68 to 72% 14 to 18% 8 to 12%

50 68 to 72% 14 to 18% 12 to 15%

51 68 to 72% 18 to 22% 3 to 5%

52 68 to 72% 18 to 22% 5 to 8%

53 68 to 72% 18 to 22% 8 to 12%

54 68 to 72% 22 to 26% 3 to 5%

55 68 to 72% 22 to 26% 5 to 8%

56 72 to 76% 10 to 14% 3 to 5%

57 72 to 76% 10 to 14% 5 to 8%

58 72 to 76% 10 to 14% 8 to 12%

59 72 to 76% 10 to 14% 12 to 15%

60 72 to 76% 14 to 18% 3 to 5%

61 72 to 76% 14 to 18% 5 to 8%

62 72 to 76% 14 to 18% 8 to 12%

63 72 to 76% 18 to 22% 3 to 5%

64 72 to 76% 18 to 22% 5 to 8%

65 76 to 80% 10 to 14% 3 to 5%

66 76 to 80% 10 to 14% 5 to 8%

67 76 to 80% 10 to 14% 8 to 12%

68 76 to 80% 14 to 18% 3 to 5%

69 76 to 80% 14 to 18% 5 to 8%

According to one embodiment, for each of the formulations 1 to 69 above, the mass proportion of HFP comonomer in the copolymer is 20 to 22%.

According to one embodiment, for each of the formulations 1 to 69 above, the mass proportion of HFP comonomer in the copolymer is 22 to 24%.

According to one embodiment, for each of the formulations 1 to 69 above, the mass proportion of HFP comonomer in the copolymer is 24 to 26%. According to one embodiment, for each of the formulations 1 to 69 above, the mass proportion of HFP comonomer in the copolymer is from 26 to 28%.

According to one embodiment, for each of the formulations 1 to 69 above, the proportion by weight of HFP comonomer in the copolymer is 28 to 30%.

According to one embodiment, for each of the formulations 1 to 69 above, the mass proportion of HFP comonomer in the copolymer is 30 to 35%.

According to one embodiment, for each of the formulations 1 to 69 above, the mass proportion of HFP comonomer in the copolymer is 35 to 40%.

According to one embodiment, for each of the formulations 1 to 69 above, the HFP comonomer can be replaced by the CTFE comonomer.

According to one embodiment, for each of the formulations 1 to 69 above, the HFP comonomer can be replaced by the TFE comonomer.

According to one embodiment, for each of the formulations 1 to 69 above, the HFP comonomer can be replaced by the TrFE comonomer.

According to one embodiment, for each of the formulations 1 to 69 above, the HFP comonomer may be replaced by the CFE comonomer.

The composition according to the invention can be manufactured by mixing PVDF and P (VDF-HFP) in the molten state (from powders or granules), in an extruder, a roller mixer or any other type of appropriate device.

The plasticizer, the fibers as well as any additives may be incorporated into the compositions during the mixing of PVDF and P (VDF-HFP), or else they may be mixed with one or other of these constituents prior to mixing them, or alternatively after the mixture of PVDF and P (VDF-HFP), or else be provided in the form of a masterbatch supplying part of one of the two constituents (PVDF or P (VDF-HFP)), according to the mixing techniques stated above.

Preferably, the fibers have a preferred orientation in the composition. This is accomplished for example by aligning the fibers in an extrusion step.

The composition according to the invention makes it possible to manufacture umbilicals and flexible tubes used on-shore and off-shore (in marine environment) for containing and / or transporting crude oil, natural gas, water and other gases. used for drilling, as defined in API 17J, API 16C and API 15RS.

The composition according to the invention also makes it possible to manufacture all types of pipes for the transport of gaseous or liquid products, in particular intended to transport gaseous products for the synthesis of chemicals or intended to transport individual consumer products, industrial or public.

The composition according to the invention also makes it possible to manufacture, alone or in combination with other products, cables, hollow bodies, binders for rechargeable batteries.

The composition according to the invention can be implemented as a layer in a multilayer structure, or it can be used to form a part integrally.

The manufacture of the above objects is preferably carried out by extrusion, the composition being directly formed during the extrusion. Alternatively, the composition can first be prepared in the form of granules, then be melted and extruded to shape the objects.

The composition according to the invention can be tested by means of the fatigue test, which is described in document WO 2010/026356. It consists in determining, for a given sample of polymer composition, the number of cycles to failure (noted NCR), that is to say the number of cycles at the end of which occurs the rupture of the sample. The higher the value of NCR, the better the result of the fatigue test.

In order to carry out a fatigue test, axisymmetric specimens are cut into the thickness of an extruded tube, with a notch curvature radius of 4 mm and a minimum radius of 2 mm. These specimens are considered to be representative of the local geometry of the tube. The cutting is performed by means of a servohydraulic dynamometer, for example of the MTS 810 type. The distance between jaws is 10 mm. The specimen is subjected to a maximum elongation of 1.4 mm and a ratio between the minimum elongation and the maximum elongation of 0.21, which corresponds to a minimum elongation of 0.3 mm, with a sinusoidal signal having a frequency of 1 Hz. The result of the test (NCR) is the average of the results obtained on 10 test pieces.

In order to carry out a hot creep test, a tensile test according to ISO 527 (type 1A test specimens at a speed of 50 mm / min) is carried out on unaged samples of the polymeric composition, with a packaging of these compounds. test pieces at a test temperature (which can be for example 130 ° C, or 150 ° C, or 165 ° C), 20 minutes before the test. The stress at the threshold of these specimens corresponds to the maximum nominal stress supported by the specimens during traction. The higher the stress, the better the creep resistance of the polymer composition at the test temperature under consideration.

EXAMPLES

The following examples illustrate the invention without limiting it. Example 1

A composition according to the invention of the following formulation is prepared:

69% of Kynar® 401 polymer (PVDF homopolymer, origin:

Arkema);

18% of Kynar Ultraflex® copolymer (VDF-HFP copolymer containing between 23 and 24% by weight of HFP, origin: Arkema);

- 3% dibutyl sebacate (plasticizer);

- 10% carbon fiber.

The composition is obtained by melt blending of powders or granules comprising the two polymeric compounds, as well as the plasticizer and the fibers, on a Buss-brand PR 46 co-kneader with a diameter of 46 millimeters, 15 times greater in length. at its diameter, equipped with a recovery extruder, at a flow rate of 10 kg / h. The rotational speed of the screw of the co-kneader is 150 rpm and that of the re-extruder is about 15 rpm. The temperature profile is set so as to obtain a material temperature between 200 ° C and 230 ° C.

The granules obtained are then extruded into a strip or tube with a thickness between 6 and 10 mm using a single-screw extruder equipped with a suitable die. The temperature profile is set so as to obtain a material temperature of between 210 ° C. and 250 ° C.

Example 2

Another composition according to the invention is prepared with the same formulation as in the preceding example, except that the 10% of carbon fibers are replaced by 10% of crosslinked PVDF fibers.

The first step is the production of the crosslinked PVDF fibers.

These are made by extrusion of Kynar® 705 polymer (PVDF homopolymer having a viscosity at 230 ° C under 100 s ^-1 of 250 Pa.s, marketed by Arkema). The diameter of the fibers is between 10 and 20 μιτι and their length is between 2 and 4 mm.

These fibers are irradiated under 50 kgray by a source of cobalt 60, causing their crosslinking. These fibers are then introduced at a level of 10% into the formulation, according to the following protocol.

The composition is obtained by melt blending of powders or granules comprising the two polymeric compounds, as well as the plasticizer and the fibers, on a Buss-brand PR 46 co-kneader with a diameter of 46 millimeters, 15 times greater in length. at its diameter and equipped with a recovery extruder, at a flow rate of 10 kg / h. The speed of rotation of the screw of the co-kneader is 150 rpm and that of the re-extruder is about 15 rpm and the temperature profile is set so as to obtain a material temperature of between 200 ° C. C and 230 ° C.

Claims

Composition comprising:

from 60 to 80% by weight of a polyvinylidene fluoride;

from 10 to 30% by weight of a copolymer of vinylidene fluoride and a comonomer;

a plasticizer present in the composition in a mass proportion of 1 to 5%, and

from 3 to 20% by weight of fibers.

The composition of claim 1, wherein the plasticizer is selected from dibutyl sebacate, dioctyl phthalate, N-n-butylsulfonamide, polymeric polyesters and combinations thereof, and preferably is dibutyl sebacate.

Composition according to one of Claims 1 or 2, in which the plasticizer is present in a mass proportion of 1.5 to 3.5%, preferably of 1.5 to 2.5%.

Composition according to one of claims 1 to 3, wherein the fibers are selected from carbon fibers, glass fibers, carbon nanotubes, carbon nanofibers, synthetic fibers and combinations thereof.

Composition according to one of claims 1 to 4, wherein the fibers are crosslinked polyvinylidene fluoride fibers.

Composition according to one of claims 1 to 5, wherein the copolymer is present in a mass proportion of 15 to 25%.

7. Composition according to one of claims 1 to 6, wherein the mass proportion of (co) monomer (s) other than vinylidene fluoride in the copolymer is included in the range 15 to 24%, preferably 19 to 24% inclusive.

Composition according to one of Claims 1 to 7, in which the fluorinated comonomer is chosen from vinyl fluoride, trifluoroethylene, chlorotrifluoroethylene (CTFE), 1,2-difluoroethylene, tetrafluoroethylene (TFE) and hexafluoropropylene (HFP). ), perfluoro (alkyl vinyl) ethers such as perfluoro (methylvinyl) ether (PMVE), perfluoro (ethylvinyl) ether (PEVE), perfluoro (propylvinyl) ether (PPVE), perfluoro (1,3-dioxozole) ; perfluoro (2,2-dimethyl-1,3-dioxol) (PDD), the product of formula CF2 = CFOCF2CF (CF3) OCF2CF2X wherein X is SO ₂ F, CO ₂ H, CH ₂ OH; CH ₂ OCN or CH ₂ OPO ₃ H, the product of formula CF 2 = CFOCF 2 CF 2 SO 2 F; the product of formula F (CF 2) nCH 2 OCF = CF 2 in which n is 1, 2,3,4 or 5, the product of formula R 1 CH 2 OCF = 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 R3OCF = CH2 in which R3 is F (CF2) z and z is 1, 2, 3, or 4 or alternatively perfluorobutylethylene (PFBE), fluoroethylenepropylene (FEP), 3,3,3-trifluoropropene, 2-trifluoromethyl-3,3,3-trifluoro-1-propene, 2,3,3,3-tetrafluoropropene or HFO-1234yf, E-1, 3,3,3-tetrafluoropropene or HFO-1234zeE, Z -1,3,3,3-tetrafluoropropene or HFO-1234zeZ, 1,1,2,3-tetrafluoropropene or HFO-1234yc, Ie, 2,3,3-tetrafluoropropene or HFO-1234ye, 1, 1, 3 , 3-tetrafluoropropene or HFO-1234zc and chlorotetrafluoropropene or HCFO-1224.

Composition according to one of Claims 1 to 8, in which the comonomer is hexafluoropropylene.

10. Composition according to one of claims 1 to 9, wherein the intrinsic viscosity of the mixture of PVDF homopolymer and fluorinated copolymer is greater than 2 dl / g.

11. Composition according to one of claims 1 to 10 having a melt apparent viscosity greater than 60000 Pa.s at a speed gradient of 1 sec ^-1 .

12. Composition according to one of claims 1 to 1 1, consisting of homopolymer of polyvinylidene fluoride, the copolymer of vinylidene fluoride and hexafluoropropylene, carbon fibers and plasticizer.

13. A method of manufacturing a composition according to one of claims 1 to 12, comprising the mixture of polyvinylidene fluoride, copolymer, fibers and plasticizer. The method of claim 13, wherein the rhomopolymer and the copolymer are in dry form when mixed with the plasticizer, preferably in the form of powders, and preferably the mixture is made in the molten state. The method according to one of claims 13 to 14, comprising mixing the homopolymer and the latex copolymer, drying the homopolymer and copolymer mixture, and combining the dried mixture with the plasticizer and the co-polymers. fibers, preferably in the molten state.

16. Pipe comprising at least one layer consisting of a composition according to one of claims 1 to 12.

17. Polymeric sheath of flexible hoses used for transporting fluids from oil and gas operations, said sheath consisting of a composition according to one of claims 1 to 12.