WO2002062567A2

WO2002062567A2 - Multilayer structure having a fluorinated polymer layer

Info

Publication number: WO2002062567A2
Application number: PCT/FR2002/000446
Authority: WO
Inventors: Manuel Hidalgo; Ludwik Leibler; François COURT; Joachim Merziger; Christelle Plaut
Original assignee: Atofina
Priority date: 2001-02-06
Filing date: 2002-02-05
Publication date: 2002-08-15
Also published as: AU2002241008A1; AU2002241008A8; WO2002062567A3

Abstract

The invention concerns in a first embodiment a structure comprising successively: a first polyolefin layer, an optional binding layer, and a second fluorinated polymer layer. The binder layer may be based on hydrogenated three-block copolymer ABC, or may comprise several layers: an optional layer (L1) comprising a fluorinated polymer and a polymer essentially consisting of alkyl (meth)acrylate units, a layer (L2) based on polyamide with amine ends and a layer (L3) consisting of a polyolefin functionalised with an unsaturated carboxylic acid anhydride, the layer (L3) being in contact with the polyolefin layer. Said structures are useful for making devices for transporting and storing fluids.

Description

ULTI-LAYERED STRUCTURES HAVING A POLYMER LAYER

FLUORINE

[Field of the invention]

The present invention relates to multilayer structures having a layer of fluoropolymer. These structures can be: [polyolefin / binder based on hydrogenated ABC triblock copolymer / fluoropolymer layer] or

[polyolefin / mixture of fluoropolymer and hydrogenated triblock ABC copolymer] in which the hydrogenated triblock ABC copolymer consists for example of a polystyrene block, a hydrogenated polybutadiene block and a PMMA block arranged in this order. In the first structure, the binder based on hydrogenated triblock ABC copolymer can be replaced by several layers of other polymers such as polyamides and functionalized polyolefins.

The fluoropolymer layer and the mixture of fluoropolymer and hydrogenated ABC triblock copolymer layer are barrier layers to many fluids and in particular to gasoline. These structures, in which the polyolefin is placed outside, are useful for making devices for transferring or storing fluids and more particularly pipes, tanks, tank spouts, that is to say the pipe which serves to fill the tank, bottles and containers. The invention is useful for a fluid such as petrol in automobiles by avoiding losses through the structure so as not to pollute the environment. It is also useful for liquids containing volatile substances by avoiding a depletion of the liquid in this volatile substance. The invention is also useful for engine coolant, for oil and for the fluid of the air conditioning system.

The invention also relates to structures in which the polyolefin is placed inside, they are useful for example for pipes distributing drinking water and which one wants to protect from pollution brought in from the outside. The structures of the invention can be manufactured according to the usual technologies of the thermoplastics industry such as coextrusion and coextrusion blow molding.

[The prior art and the technical problem]

Patent EP 731 308 describes a tube comprising an inner layer comprising a mixture of polyamide and polyolefin with a polyamide matrix and an outer layer comprising a polyamide. These polyamide-based tubes are useful for the transport of petrol and more particularly for bringing petrol from the tank of automobiles to the engine and also, but in larger diameter, for the transport of hydrocarbons in service stations. between distribution pumps and underground storage. According to another form of the invention, a layer of a polymer comprising ethylene units and vinyl alcohol (EVOH) units can be placed between the inner and outer layers. The structure is advantageously used: inner layer / EVOH / binder / outer layer.

Patent EP 558373 describes a tube for transporting petrol respectively comprising an outer polyamide layer, a binder layer and an inner layer in contact with petrol and made of fluoropolymer.

Patent WO 0077432 describes tubes very close to the previous tubes but the fluoropolymer layer contains a triblock copolymer ABC, ABC designating for example a triblock consisting of a polystyrene block, a polybutadiene block and a PMMA block arranged in this order.

Patents EP 696,301, EP 740,754 and EP 726,926 describe tubes for transporting petrol respectively comprising an outer polyamide layer, a binder layer, a PVDF (polyvinylidene fluoride) layer, a binder layer and an inner layer. made of polyamide in contact with petrol. In these prior art, the tubes (which may have an outside diameter of 8mm) have an outer polyamide layer, this layer also provides a significant part of the mechanical resistance of the tube.

Patent EP 742 236 describes fuel tanks made up of five layers which are respectively:

- high density polyethylene (HDPE);

- a binder;

- a polyamide (PA) or a copolymer having ethylene units and vinyl alcohol units (EVOH); - a binder;

- HDPE.

A sixth layer can be added between one of the binder layers and one of the HDPE layers. This sixth layer is made up of production falls following the molding of the tanks, of non-conforming tanks for a much smaller quantity. These nonconforming scraps and tanks are crushed until granules are obtained. This ground material is then remelted and extruded directly on the tank coextrusion installation. This ground material could also be melted and regranulated by an extrusion machine such as a twin screw before being reused. According to a variant, the recycled product can be mixed with the HDPE of the two extreme layers of the tank. It is for example possible to mix the granules of recycled product with the granules of virgin HDPE of these two layers. Any combination of these recycles can also be used. The rate of recycled material can represent up to 50% of the total weight of the tank. The tanks described in EP 742236 certainly have barrier properties but they are not sufficient when very low gasoline losses are sought. One cannot use, for making reservoirs, the structures described for petrol tubes having a PVDF layer indeed the external polyamide layer would be much too expensive. The prior art has proposed polyolefin / binder / PVDF structures. Thus, patent WO 9618500 describes for these structures a binder consisting of a mixture of polycaprolactone and chlorinated polyethylene. This binder is not sufficient. In these same structures, patent JP 08 336937 A1 describes a binder consisting of a polyolefin grafted with acrylic esters. As above, this binder is not sufficient.

We have now found that structures: [polyolefin / binder based on hydrogenated ABC triblock copolymer / fluoropolymer layer] or

[polyolefin / mixture of fluoropolymer and hydrogenated triblock ABC copolymer] in which the hydrogenated triblock ABC copolymer consists for example of a polystyrene block, a hydrogenated polybutadiene block and a PMMA block arranged in this order, were of very good barrier and very good mechanical quality.

The fluoropolymer layer and the mixture of fluoropolymer and hydrogenated ABC triblock copolymer layer are barrier layers to many fluids and in particular to gasoline. In the first structure, the binder based on hydrogenated triblock ABC copolymer can be replaced by several layers of other polymers such as polyamides and functionalized polyolefins.

[Brief description of the invention]

The present invention relates in a first form to a structure successively comprising:

• a first layer of polyolefin,

• a binder layer based on hydrogenated triblock ABC copolymer, • a second fluoropolymer layer, in the ABC triblock copolymer, the three blocks A, B, and C are linked together in this order, each block being either a homopolymer either a copolymer obtained from two or more monomers, block A being linked to block B and block B to block C by means of a covalent bond or an intermediate molecule linked to one of these blocks by a covalent bond and to the other block by another covalent bond, and such that:

- block A is compatible with the fluoropolymer, block B is incompatible with the fluoropolymer and is incompatible with block A and it includes hydrogenatable double bonds,

- block C is incompatible with the fluoropolymer, block A and block B.

According to a second form of the invention, the binder layer of the first form is replaced by several layers comprising respectively: • an optional layer (L1) comprising (by weight) 50 to 95% of a fluoropolymer and 5 to 50% of a polymer (P1) consisting essentially of units

(meth) alkyl acrylate,

A layer (L2) based on amino terminated polyamide,

• a layer (L3) consisting of a polyolefin functionalized with an unsaturated carboxylic acid anhydride, the layer (L3) being in contact with the polyolefin layer.

The present invention also relates, according to a third form, to a structure successively comprising: a first layer of polyolefin,

• a second layer based on a mixture of hydrogenated triblock ABC copolymer and a fluoropolymer, the ABC triblock copolymer having the same meaning as above.

In this third form, the second layer may contain an electroconductive product.

The invention also relates to structures in which the polyolefin is placed inside, they are useful for example for pipes distributing drinking water and which one wants to protect from pollution brought in from the outside.

These devices can be manufactured by the usual techniques in the thermoplastic polymer industry such as coextrusion, extrusion blow molding, calendering. With regard to reservoirs, it is also possible to thermoform the structure of the invention by two halves of the reservoir, then these two halves are welded.

[Detailed description of the invention]

As regards the first layer, the polyolefin may for example be polyethylene or polypropylene. Advantageously, HDPE is used. High density polyethylene (HDPE) is described in the Kirk-Othmer, ^4th Edition, Vol 17, pages 704 and 724-725. According to ASTM D 1248-84, an ethylene polymer having a density at least equal to 0.940. The designation HDPE relates both to homopolymers of ethylene and to its copolymers with small proportions of α-olefin. The density is advantageously between 0.940 and 0.965. In the present invention, the HDPE MFI is advantageously between 0.1 and 50. As an example, we can cite ELTEX B 2008® with density 0.958 and MFI 0.9 (in g / 10 min at 190 ° C under 2.16 kg), Finathene® MS201 B from FINA and Lupolen® 4261 AQ from BASF.

As regards the fluoropolymer, one thus designates any polymer having in its chain at least one monomer chosen from compounds containing a vinyl group capable of opening up to polymerize and which contains, directly attached to this vinyl group, at least one fluorine atom, a fluoroalkyl group or a fluoroalkoxy group.

By way of example of a monomer, mention may be made of vinyl fluoride; vinylidene fluoride (VF2); trifluoroethylene (VF3); chlorotrifluoroethylene (CTFE); 1,2-difluoroethylene; tetrafluoroethylene (TFE); Phexafluoropropylene (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); periuoro (2,2-dimethyl-1,3 -dioxole) (PDD); the product of formula CF2 = CFOCF2CF (CF3) OCF2CF2X in which X is SO2F, CO2H, CH2OH, CH2OCN or CH20PO3H; the product of formula CF2 = CFOCF2CF2SO2F; the product of formula F (CF2) nCH20CF = CF2 in which n is 1, 2, 3, 4 or 5; the product of formula R1CH2OCF = CF2 in which R1 is hydrogen or F (CF2) 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; perfluorobutyl ethylene (PFBE); 3,3,3-trifluoropropene and 2-trifluoromethyl-3, 3, 3 -trifluoro- 1 -propene.

The fluoropolymer can be a homopolymer or a copolymer, it can also include non-fluorinated monomers such as ethylene. Advantageously, the fluoropolymer is chosen from:

-Homo- and copolymers of vinylidene fluoride (VF2) preferably containing at least 50% by weight of VF2, the copolymer being chosen from chlorotrifluoroethylene (CTFE), hexafluoropropylene (HFP), trifluoroethylene (VF3) and tetrafluoroethylene ( TFE), - Homo- and copolymers of trifluoroethylene (VF3),

- The copolymers, and in particular terpolymers, combining the residues of chlorotrifluoroethylene (CTFE), tetrafluoroethylene (TFE), hexafluoropropylene (HFP) and / or ethylene units and optionally VF2 and / or VF3 units. Preferably, the fluoropolymer is poly (vinylidene fluoride)

(PVDF) homopolymer. The fluoropolymer of the second layer can comprise (i) optionally an electroconductive product and (ii) optionally an ABC triblock copolymer. These ABC triblocks are described below

As regards the electroconductive product in the fluoropolymer, these are all the conductors of electricity. By way of example, mention may be made of metals and carbon-based products. Examples of carbon-based products that may be mentioned include graphite, carbon black and carbon fibers. It would not be departing from the scope of the invention to use several electrically conductive elements. The carbon-based products that can be used are described in Handbook of fillers 2 ^nd Edition published by Chem Tec Publishing 1999 page 62 § 2.1.22, page 92 § 2.1.33 and page 184 § 2.2.2.

Advantageously, the electroconductive product is chosen from carbon blacks: Carbon blacks can be semiconductor blacks, conductors, these carbon blacks, have a low BET surface. Among the carbon blacks which can be used, those from the company MMM Carbon are particularly satisfactory. We will particularly remember blacks whose nitrogen adsorption surface is less than 500 m ² / g. Advantageously, these carbon blacks have a nitrogen adsorption surface of less than 100 m ² / g. Among these different types the ENSACO ^® 250 is particularly suitable for the application.

As regards the ABC triblock copolymer, the ABC triblocks which can be used to modify the fluoropolymer in the second layer of the first and second forms of the invention are described below. In these triblocks, the blocks B can be hydrogenatable (for example those based on dienes) or not be hydrogenatable (for example those based on butyl acrylate). The hydrogenated ABC triblocks produced by hydrogenation of the hydrogenable triblocks and used in the first and third forms of the invention are the same as the previous ones except that they have only hydrogenable B blocks.

The block copolymer comprising at least three blocks A, B and C is such that block A is connected to block B and block B to block C by means of one or more several simple covalent bonds. In the case of several covalent bonds, between block A and block B and / or between block B and block C, there may be a single motif or a series of motifs serving to join the blocks together. In the case of a single motif, the latter can come from a so-called moderating monomer used in the synthesis of the triblock. In the case of a chain of units, this can be an oligomer resulting from a chain of monomer units of at least two different monomers in an alternating or random order. Such an oligomer can link block A to block B and the same oligomer or a different oligomer can link block B to block C. Block A of an ABC copolymer is considered to be compatible with the fluoropolymer if polymer A identical to this block (therefore without sequences B and C) is compatible with this resin in the molten state. Similarly, blocks A and B are considered to be incompatible if the polymers A and B identical to these blocks are incompatible. In general, by compatibility between two polymers is meant the ability of one to dissolve in the other in the molten state or their total miscibility. Otherwise, the polymers or blocks are said to be incompatible.

The lower the enthalpy of mixing two polymers, the greater their compatibility. In some cases, there is a favorable specific interaction between the monomers which results in a negative mixing enthalpy for the corresponding polymers. In the context of the present invention, it is preferred to use compatible polymers whose enthalpy of mixing is negative or zero. The enthalpy of mixing cannot however be conventionally measured for all polymers, and therefore compatibility can only be determined indirectly, for example by measurements of viscoelastic analysis in torsion or oscillation or by differential scanning calorimetry. For compatible polymers, 2 Tg can be detected for the mixture: at least one of the two Tg is different from the Tg of the pure compounds and lies in the temperature range between the two Tg of the pure compounds. The mixture of two completely miscible polymers has a single Tg.

Other experimental methods can be used to demonstrate the compatibility of polymers, such as turbidity measurements, light scattering measurements, infrared measurements (L. A Utracki, Polymer Alloys and Blends, pp 64-117).

Miscible or compatible polymers are listed in the literature, see for example J. Brandrup and E.H. Immergut: Polymer Handbook, 3rd Edition, Wiley & Sons 1979, New York 1989, pp. VI / 348 to VI / 364; O. Olabisi, L. M. Robeson and M. T. Shaw: Polymer Miscibility, Académie Press, New York 1979, pp. 215-276; L.A. Utracki: Polymer Alloys and Blends, Hanser Verlag, Munich 1989. The lists appearing in these references are given by way of illustration and are, of course, not exhaustive.

Advantageously, block A is chosen from homo- and copolymers of alkyl (alkyl) acrylate and, for example, methyl methacrylate (MAM) and / or methyl or ethyl acrylate and / or those derived from vinyl acetate. Advantageously, the block A is Poly (methyl methacrylate) (PMMA). Preferably, this PMMA is syndiotactic and its glass transition temperature TgtΔ), measured by differential thermal analysis, is from + 120 ° C to + 140 ° C.

Advantageously, the Tg of B is less than 0 ° C and preferably less than - 40 ° C.

The monomer used to synthesize the elastomeric block B can be a diene chosen from butadiene, isoprene, 2,3-dimethyl-1, 3-butadiene, 1, 3-pentadiene, 2-phenyl-1, 3 butadiene. B is advantageously chosen from poly (dienes), in particular poly (butadiene), poly (isoprene) and their random copolymers, or also from poly (dienes) partially or completely hydrogenated. Among the polybutadienes, those with the lowest Tg are advantageously used, for example polybutadiene-1, 4 of Tg (around -90 ° C.) lower than that of polybutadiene-1,2. (around 0 ° C). B blocks can also be hydrogenated. This hydrogenation is carried out according to the usual techniques. The monomer used to synthesize the elastomeric block B can also be an alkyl (meth) acrylate, the following Tg are obtained in parentheses according to the name of the acrylate: ethyl acrylate (-24 ° C), l butyl acrylate, (-54 ° C), 2-ethylhexyl acrylate (-85 ° C), hydroxyethyl acrylate (-15 ° C) and 2-ethylhexyl methacrylate (-10 ° C ). Advantageously, butyl acrylate is used. The acrylates are different from those of block A to respect the condition of incompatible B and A.

Preferably, the blocks B consist mainly of polybutadiene-1, 4. Preferably, block C has a glass transition temperature Tgtc) or a melting temperature Tf (Q) higher than the Tg (B) of block B- This characteristic gives the possibility that block C is in the glassy state or either in a partially crystalline state and the block B in the elastomeric state, for the same temperature of use Tp. According to the present invention, it is possible to choose the nature of the blocks B to have a certain determined Tg (β) and thus, at the temperature of use Tp of the material or of the object formed from the mixture, d '' have an elastomeric or flexible state of these block polymers B. On the other hand, block polymers C can have a Tgtc) or a Tf greater than Tg), they can be in a glassy state relatively rigid at the same temperature of use .

As blocks C are incompatible with the fluoropolymer, blocks A and blocks B, they form a rigid discrete phase inside the material by forming nanodomains included in the material and serving as anchors in the area of a of the ends of each block B. The other end of each block B is connected to a block A which has a strong affinity with the fluoropolymer. This strong affinity provides a second anchoring in the area of the second end of block B.

Advantageously, the block C is chosen from homopolymers or copolymers of styrene or of α-methylstyrene. The triblocks which contain sequences derived from alkyl (alkyl) acrylate can in particular be prepared by anionic polymerization, for example according to the methods described in patent applications EP 524,054 and EP 749,987. Preferably, the ABC triblock is Poly (methyl methacrylate-b-butadiene-> styrene).

The ABC triblock copolymer may contain, as secondary products of its synthesis, a diblock copolymer BC and optionally homopolymer C. The ABC triblock copolymer may also contain, as secondary products of its synthesis, a diblock copolymer AB and optionally homopolymer A.

In fact, the synthesis of a triblock copolymer is preferably done by successively combining block A with block B then with block C or conversely block C with block B then with block A according to the nature of the three blocks A, B and C. Block A is by definition the one which is compatible with the fluoropolymer. The ABC triblock copolymer can also contain symmetrical linear or star block copolymers of the ABA or CBC type.

Advantageously, the total amount by weight of the secondary synthesis products, that is to say of these homopolymers A, C or block copolymers AB, BC, ABA and CBC is less than 2 times the amount of triblock ABC. Preferably this amount is less than once and better still 0.5 times the amount of ABC triblock. More precisely, the secondary products are essentially the BC diblock, the amount of BC can be between 25 and 35 parts by weight for respectively 75 to 65 parts of ABC and is advantageously around 30 parts for 70 parts of ABC.

The number-average molecular mass (M _n ) of the triblock copolymer, including the secondary synthesis products, is greater than or equal to 20,000 g.moM, and preferably between 50,000 and 200,000 g.mol ^"1. Advantageously, the triblock copolymer ABC, including secondary products, consists of:

- 20 to 93 and preferably 30 to 70 parts by weight of sequences A,

- 5 to 68 and preferably 10 to 40 parts by weight of B sequences, - 2 to 65 and preferably 5 to 40 parts by weight of C sequences.

The Applicant has found that in the case of triblocks, the secondary products resulting from the synthesis, such as diblocks or homopolymers, were not detrimental to the mechanical properties of the mixture. By way of example, the second layer of the first and second forms contains by weight (the total being 100%):

65 to 97% of fluoropolymer,

0 to 25% of electroconductive product,

3 to 15% of ABC triloc copolymer. As a conductive layer, its composition by weight can be, the total being 100%:

65 to 92% and advantageously 70 to 85% of fluoropolymer,

5 to 25% and advantageously 10 to 20% of electroconductive product,

3 to 15% and advantageously 5 to 10% of ABC triloc copolymer.

As regards the hydrogenated ABC triblocks, these are the copolymers mentioned above, the block B of which is hydrogenated, obviously in this case the blocks B to be hydrogenated consist of dienes and not of (meth) acrylates. The hydrogenation rate can be between 40 and 100% and preferably between 90 and 100%. A rate of 70% means that 70% of the remaining double bonds of block B which did not participate in the formation of this block B have been hydrogenated. This hydrogenation can be carried out by the usual techniques such as by bringing the triblock into contact with hydrogen in the presence of Wilkinson type catalysts or by bringing the triblock into contact with hydrazine in the presence of a little water. oxygenated. The higher the hydrogenation rate, the better the quality of the binder, that is to say its ability to adhere the first and the second layer in the first and third form. In the first form of the invention, advantageously these hydrogenated triblocks are diluted in a polyolefin, examples of polyolefins are given in the description of the layer (L3) below. Hydrogenated triblocks are often viscous and therefore can be difficult to use, which is why they are diluted. The dilution rate depends on the viscosity desired in order to be able to form the structures of the invention. In this mixture of polyolefins and hydrogenated triblocks, it is also possible to add a fluoropolymer, an optionally functionalized PMMA (for example copolymers of MMA and acrylic acid which may comprise up to 15% by weight of acid), cores acrylic shell (or core-shell copolymer). In the third form of the invention, the mixture is advantageously such that either the fluoropolymer and the hydrogenated triblock form cocontinuous phases (for example the fluoropolymer is in proportion from 40 to 60% by volume for respectively 60 to 40% of triblock hydrogenated) or the fluoropolymer forms the matrix (for example the fluoropolymer is in volume proportion from 45 to 75% for respectively 25 to 55% of hydrogenated triblock).

Regarding the layer (L1) of the binder of the second form of the invention, the fluoropolymer can be chosen from those mentioned for the second layer. They can be identical or different, advantageously it is PVDF homopolymer.

The polymer (P1) essentially consisting of alkyl (meth) acrylate units can also comprise acid, acid chloride, alcohol and anhydride functions. By way of example of polymer (P1), mention may be made of homopolymers of an alkyl (meth) acrylate. Alkyl (meth) acrylates are described in KIRK-OTHMER, Encyclopedia of chemical technology, 4th edition in Vol 1 pages 292-293 and in Vol 16 pages 475-478. Mention may also be made of copolymers of at least two of these (meth) acrylates and copolymers of at least one (meth) acrylate with at least one monomer chosen from acrylonitrile, butadiene, styrene, isoprene provided that the proportion of (meth) acrylate is at least 50 mol%. (P1) is advantageously PMMA. These polymers (P1) either consist of the monomers and optionally the comonomers mentioned above and do not contain an impact modifier or they additionally contain an acrylic impact modifier. The acrylic impact modifiers are, for example, random or block copolymers of at least one monomer chosen from styrene, butadiene, isoprene and at least one monomer chosen from acrylonitrile and (meth) alkyl acrylate, they can be of the core-shell type. These acrylic impact modifiers can be mixed with the polymer (P1) once prepared or be introduced during the polymerization of (P1) or prepared simultaneously during the polymerization of (P1). The amount of acrylic impact modifier may for example be from 0 to 30 parts per 100 to 70 parts of (P1) and advantageously from 5 to 20 parts per 95 to 20 parts of (P1). It would not be departing from the scope of the invention if (P1) were a mixture of two or more of the preceding polymers.

Advantageously, this layer (L1) comprises 60 to 80 parts (by weight) of fluoropolymer for 40 to 20 parts of (P1). Suitable polymers for (P1) are SUMIPEX TR ^® from Sumitomo ^® and OROGLASS HT121 ^® from Atoglass and for the fluoropolymer KYNAR 720 ^® from ATOFINA.

This layer (L1) can also comprise an impact modifier which can be chosen from modifiers of the core-shell type (core-shell), acrylic polymers other than (P1) and their mixtures. The amount of these impact modifiers can be from 2 to 60 parts by weight per 100 parts of the whole of the fluoropolymer and of (P1). As regards the core-shell copolymer (AA) it is in the form of fine particles having an elastomer core and at least one thermoplastic shell, the particle size is generally less than μm and advantageously between 200 and 500 nm . Examples of cores that may be mentioned are homopolymers of isoprene or butadiene, copolymers of isoprene with at most 30 mol% of a vinyl monomer and copolymers of butadiene with at most 30 mol% of a vinyl monomer. The vinyl monomer can be styrene, an alkylstyrene, acrylonitrile or an alkyl (meth) acrylate. Another core family is made up of homopolymers of an alkyl (meth) acrylate and copolymers of an alkyl (meth) acrylate with at most 30 mol% of a vinyl monomer. The alkyl (meth) acrylate is advantageously butyl acrylate. The vinyl monomer can be styrene, an alkylstyrene, acrylonitrile, butadiene or isoprene. The core of the copolymer (AA) can be crosslinked in whole or in part. It suffices to add at least difunctional monomers during the preparation of the core, these monomers can be chosen from poly (meth) acrylic esters of polyols such as butylene di (meth) acrylate and trimethylol propane trimethaciγlate. Other difunctional monomers are for example divinylbenzene, trivinylbenzene, vinyl acrylate and vinyl methacrylate. The heart can also be crosslinked by introducing therein, by grafting or as a comonomer during the polymerization, unsaturated functional monomers such as anhydrides of unsaturated carboxylic acids, unsaturated carboxylic acids and unsaturated epoxides. By way of example, mention may be made of maleic anhydride, (meth) acrylic acid and glycidyl methacrylate. The bark or barks are homopolymers of styrene, of an alkylstyrene or of methyl methacrylate or of copolymers comprising at least 70 mol% of one of these preceding monomers and at least one comonomer chosen from the other preceding monomers , vinyl acetate and acrylonitrile. The bark can be functionalized by introducing, by grafting or as a comonomer during the polymerization, unsaturated functional monomers such as anhydrides of unsaturated carboxylic acids, unsaturated carboxylic acids and unsaturated epoxides. By way of example, mention may be made of maleic anhydride, (meth) acrylic acid and glycidyl methacrylate. By way of example, mention may be made of core-shell copolymers (AA) having a polystyrene shell and core-shell copolymers (AA) having a PMMA shell. There are also core-shell copolymers (AA) having two shells, one made of polystyrene and the other outside of PMMA. Examples of copolymer (AA) and their preparation process are described in the following patents: US 4,180,494, US 3,808,180, US 4,096,202, US 4,260,693, US 3,287,443, US 3,657,391, US 4,299,928, US 3,985,704.

Advantageously, the heart represents, by weight, 70 to 90% of (AA) and the bark 30 to 10%.

As an example of copolymer (AA), mention may be made of that consisting of (i) from 75 to 80 parts of a core comprising at least 93% of butadiene, 5% of styrene and 0.5 to 1% of divinylbenzene and (ii) 25 to 20 parts of two bark of essentially the same weight, one inside made of polystyrene and the other outside made of PMMA.

As regards the layer (L2) of the second form of the invention, it is a homopolymer or copolymer polyamide with amino endings or a mixture of polyamides, at least one being with amino endings. Polyamide means condensation products:

- one or more amino acids, such as aminocaproic, amino-7-heptanoic, amino-11-undecanoic and amino-12-dodecanoic acids of one or more lactams such as caprolactam, oenantholactam and lauryllactam;

- one or more diamine salts or mixtures such as hexamethylenediamine, dodecamethylenediamine, metaxylyenediamine, bis-p aminocyclohexylmethane and trimethylhexamethylene diamine with diacids such as isophthalic, terphthalic, adipic, azelaic, azelaic, dodecane.

By way of example of a polyamide, mention may be made of PA 6, PA 6-6, PA 11 and PA 12.

Copolyamides can also be advantageously used. Mention may be made of the copolyamides resulting from the condensation of at least two alpha omega aminocarboxylic acids or of two lactams or of a lactam and of an alpha omega aminocarboxylic acid. Mention may also be made of the copolyamides resulting from the condensation of at least one alpha omega aminocarboxylic acid (or a lactam), at least one diamine and at least one dicarboxylic acid.

By way of example of lactams, mention may be made of those having 3 to 12 carbon atoms on the main ring and which can be substituted. Examples that may be mentioned include β.β-dimethylpropriolactam, α, α-dimethylpropriolactam, amylolactam, caprolactam, capryllactam and lauryllactam. By way of example of alpha omega aminocarboxylic acid, mention may be made of amino undecanoic acid and aminododecanoic acid. By way of example of dicarboxylic acid, mention may be made of adipic acid, sebacic acid, acid isophthalic, butanedioic acid, 1,4 cyclohexyldicarboxylic acid, terephthalic acid, sodium or lithium salt of sulphoisophthalic acid, dimerized fatty acids (these dimerized fatty acids have a dimer content of at least less 98% and are preferably hydrogenated) and the dodecanedioic acid HOOC- (CH ₂ ) 10-COOH.

The diamine can be an aliphatic diamine having from 6 to 12 atoms, it can be arylic and / or cyclic saturated. Examples include hexamethylenediamine, piperazine, tetramethylene diamine, octamethylene diamine, decamethylene diamine, dodecamethylene diamine, 1,5 diaminohexane, 2,2,4-trimethyl-1,6 -diamino-hexane, polyols diamine, isophorone diamine (IPD), methyl pentamethylenediamine (MPDM), bis (aminocyclohexyl) methane (BACM), bis (3-methyl-4 aminocyclohexyl) methane (BMACM).

Examples of copolyamides that may be mentioned are copolymers of caprolactam and lauryl lactam (PA 6/12), copolymers of caprolactam, adipic acid and hexamethylene diamine (PA 6 / 6-6), copolymers of caprolactam, lauryl lactam, adipic acid and hexamethylene diamine (PA 6/12 / 6-6), copolymers of caprolactam, lauryl lactam, 11 undecanoic amino acid, azelaic acid and hexamethylene diamine (PA 6 / 6-9 / 11/12), copolymers of caprolactam, lauryl lactam, amino 11 undecanoic acid, adipic acid and hexamethylene diamine (PA 6 / 6-6 / 11 / 12), copolymers of lauryl lactam, azelaic acid and hexamethylene diamine (PA 6-9 / 12). Advantageously, the copolyamide is chosen from PA 6/12 and PA 6 / 6-6. The advantage of these copolyamides is their lower melting temperature than that of PA 6.

To obtain amino terminations, it suffices to carry out the synthesis in the presence of an excess of diamine or for polyamides (and copolyamides) which are produced from lactam or alpha omega aminocarboxylic acid to use a diamine or a monoamine as chain limiter.

By way of example, mention may be made of (1) mixtures of miscible polyamides and (2) single-phase mixtures resulting from the transamidation of polyamide and semi aromatic amorphous polyamide. Advantageous mixtures are those which are still crystalline and transparent, that is to say microcrystalline, for example mixtures comprising by weight 70% of PA 12 and 30% of PA 12 / BMACM-1 / BMACM-T, "I" and " T "denoting iso and terphthalic acids respectively. Mention may also be made of PA BMACM-12 and PA PACM-12 (PACM represents para amino dicyclohexylmethane).

It would not be departing from the scope of the invention to use mixtures of polyamides with a polyolefin. Advantageously, these mixtures have a polyamide matrix, that is to say that they contain (by weight) 55 to 100 parts of polyamide for 0 to 45 parts of polyolefin, the polyolefin can be functionalized or be a mixture of a functionalized polyolefin and d '' a non-functionalized polyolefin. By way of example, it is possible to use the functionalized and non-functionalized polyolefins described in layer (L3). A particularly suitable polyamide is PA 12 AESNO TL ^® of

Elf Atochem®, which allows, if the polymer (P1) of the possible layer (L1) contains functions, to achieve via a chemical reaction a covalent bond stable over time with the anhydride, acid, acid chloride or alcohol functions of the polymer (P1).

As regards the layer (L3) of the second form of the invention, it consists of a polyolefin functionalized with an unsaturated carboxylic acid anhydride. The presence of the anhydride function allows an imidation reaction with the amino functions of the layer (L2) allowing the formation of a stable bond over time. This functionalized polyolefin is often described in the prior art under the qualifier of coextrusion binder.

A polyolefin is conventionally a homopolymer or copolymer of alpha olefins or of diolefins, such as for example, ethylene, propylene, butene-1, octene-1, butadiene. By way of example, there may be mentioned: - homopolymers and copolymers of polyethylene, in particular LDPE, HDPE, LLDPE (linear low density polyethylene, or low density polyethylene linear), VLDPE (very low density polyethylene, or metallocene polyethylene.

-propylene homopolymers or copolymers.

- ethylene / alpha-olefin copolymers such as ethylene / propylene, EPR (abbreviation of ethylene-propylene-rubber) and ethylene / propylene / diene

(EPDM).

- the styrene / ethylene-butene / styrene block copolymers (SEBS), styrene / butadiene / styrene (SBS), styrene / isoprene / styrene (SIS), styrene / ethylene-propylene / styrene (SEPS). - copolymers of ethylene with at least one product chosen from salts or esters of unsaturated carboxylic acids such as alkyl (meth) acrylate (for example methyl acrylate), or vinyl esters of carboxylic acids saturated such as vinyl acetate, the proportion of comonomer up to 40% by weight. The functionalized polyolefin of the layer (L3) can be a polymer of alpha olefins having unsaturated carboxylic acid anhydride units. By way of example, mention may be made of the preceding polyolefins grafted or copolymerized with anhydrides of unsaturated carboxylic acids. The grafting methods are known to those skilled in the art. It would not go beyond the scope of the invention to use unsaturated carboxylic acids as well as the derivatives of these acids and anhydrides. By way of example, mention may be made of acrylic acid, methacrylic acid, maleic acid, fumaric acid, itaconic acid, crotonic acid, itaconic anhydride, nadic anhydride, maleic anhydride and substituted maleic anhydrides such as for example dimethyl maleic anhydride. Examples of derivatives that may be mentioned include salts, amides, imides and esters such as sodium mono and dimaleate, acrylamide, maleimide and dimethyl fumarate. (meth) acrylic acid can be totally or partially neutralized by metals such as Zn, Ca, Li. A functionalized polyolefin is for example a PE / EPR mixture, the weight ratio of which can vary within wide limits, for example between 40/60 and 90/10, said mixture being co-grafted with an anhydride, in particular maleic anhydride, according to a grafting rate for example of 0.01 to 5% by weight. Various examples of constituents of (L3) are cited below.

As a first example, mention may be made of the mixture which comprises (i) a high density polyethylene (HDPE) and (ii) a mixture of a polyethylene (C1) and of a polymer (C2) chosen from elastomers, polyethylenes very low density and ethylene copolymers, the mixture (C1) + (C2) being co-grafted with an unsaturated carboxylic acid.

As a second example, mention may be made of mixtures comprising:

- 5 to 30 parts of a polymer (D) itself comprising a mixture of a polyethylene (D1) of density between 0.910 and 0.940 and of a polymer (D2) chosen from elastomers, very low polyethylenes density and metallocene polyethylenes, the mixture (D1) + (D2) being co-grafted with an unsaturated carboxylic acid,

- 95 to 70 parts of a polyethylene (E) with a density between 0.910 and 0.930,

- the mixture of (D) and (E) being such that:

^• its density is between 0.910 and 0.930, - the content of grafted unsaturated carboxylic acid is between 30 and 10,000 ppm, - the MFI (ASTM D 1238 - 190 ° C - 2.16 kg) is between 0.1 and

3 g / 10 min The MFI designates the melt flow index.

The density of the binder is advantageously between 0.915 and 0.920. Advantageously (D1) and (E) are LLDPE, preferably they have the same comonomer. This comonomer can be chosen from is 1-hexene, 1-octene and 1-butene.

As a third example, mention may be made of mixtures comprising:

- 5 to 30 parts of a polymer (F) itself comprising a mixture of a polyethylene (F1) of density between 0.935 and 0.980 and of a polymer (F2) chosen from elastomers, very low polyethylenes density and ethylene copolymers, the mixture (F1) + (F2) being co-grafted with an unsaturated carboxylic acid, - 95 to 70 parts of a polyethylene (G) with a density between 0.930 and 0.950,

- the mixture of (F) and (G) being such that:

its density is between 0.930 and 0.950 and advantageously between 0.930 and 0.940,

the content of grafted unsaturated carboxylic acid is between 30 and 10,000 ppm,

- the MFI (melt flow index) measured according to

ASTM D 1238 at 190 ° C - 21.6 kg is between 5 and 100. As a fourth example, mention may be made of polyethylene grafted with maleic anhydride having an MFI 0.1 to 3, with a density between 0.920 and

0.930 and which contains 2 to 40% by weight of insoluble in n-decane at 90 ° C.

To determine the insolubles in n-decane, the grafted polyethylene is dissolved in n-decane at 140 ° C., it is cooled to 90 ° C., products precipitate; then it is filtered and the rate of insolubles is the percentage by weight which precipitates and is collected by filtration at 90 ° C. If the rate is between 2 and

40% the binder has good resistance to petrol.

Advantageously, the grafted polyethylene is diluted in an ungrafted polyethylene and such that the binder is a mixture of 2 to 30 parts of a grafted polyethylene of density between 0.930 and 0.980 and from 70 to 98 parts of an ungrafted polyethylene of density preferably between 0.910 and 0.940

0.915 and 0.935.

As a fifth example, mention may be made of mixtures comprising:

50 to 100 parts of a homo or copolymer polyethylene (J) with a density greater than or equal to 0.9,

0 to 50 parts of a polymer (K) chosen from (K1) polypropylene homo or copolymer, (K2) poly (1 -butene) homo or copolymer and (K3) polystyrene homo or copolymer,

"the quantity of (J) + (K) being 100 parts," the mixture of (J) and (K) being grafted with at least 0.5% by weight of a functional monomer, This grafted mixture itself being diluted in at least one homo polyethylene or copolymer (L) or in at least one polymer of elastomeric nature (M) or in a mixture of (L) and (M),

According to one form of the invention (J) is an LLDPE of density 0.91 to 0.930, the comonomer having from 4 to 8 carbon atoms. According to another form of the invention (K) is a HDPE, advantageously of density at least 0.945 and preferably 0.950 to 0.980.

Advantageously, the functional monomer is maleic anhydride and its content is from 1 to 5% by weight of (J) + (K). Advantageously (L) is an LLDPE whose comonomer has from 4 to 8 carbon atoms and preferably its density is at least 0.9 and preferably 0.910 to 0.930.

Advantageously, the quantity of (L) or (M) or (L) + (M) is 97 to 75 parts for 3 to 25 parts of (J) + (K), the quantity of (J) + (K) + (L) + (M) being 100 parts.

As a sixth example, mention may be made of mixtures consisting of a polyethylene of the HDPE, LLDPE, VLDPE or LDPE type, 5 to 35% of a grafted metallocene polyethylene and 0 to 35% of an elastomer, the total being 100% . As a seventh example, mention may be made of mixtures comprising:

- at least one polyethylene or one copolymer of ethylene,

at least one polymer chosen from polypropylene or a propylene copolymer, homo or copolymer poly (1 -butene), homo or copolymer polystyrene and preferably polypropylene, this mixture being grafted with a functional monomer, this grafted mixture being itself optionally diluted in at least one polyolefin or in at least one polymer of elastomeric nature or in their mixture. In the preceding mixture which is grafted, the polyethylene advantageously represents at least 50% of this mixture and preferably 60 to 90% by weight.

Advantageously, the functional monomer is chosen from carboxylic acids and their derivatives, acid chlorides, isocyanates, oxazolines, epoxides, amines or hydroxides and preferably anhydrides of unsaturated dicarboxylic acids.

As an eighth example, mention may be made of mixtures comprising: at least one polyethylene LLDPE or VLDPE - at least one elastomer based on ethylene chosen from ethylene-propylene copolymers and ethylene-butene copolymers, this mixture of polyethylene and elastomer being grafted with an unsaturated carboxylic acid or a functional derivative of this acid, this cografted mixture being optionally diluted in a polymer chosen from homo or copolymeric polyethylenes and block copolymers of styrene, the binder having

(a) an ethylene content of not less than 70 mol%

(b) a content of carboxylic acid or its derivative, of 0.01 to 10% by weight of the binder and

(c) an MFI- ^ Q / MF ^ ratio of 5 to 20, where MFI ₂ is the melt flow index at 190 ° C under a load of 2.16 kg, measured according to ASTM D1238, MF110 is the melt flow index at 190 ° C under a load of 10 kg according to ASTM D1238.

The first layer may consist of a layer of virgin HDPE and a layer of recycled polymers originating from scrap during the manufacture of the transfer or storage devices or of these non-conforming devices as explained in the prior art already cited. This recycled layer is located on the side of the binder layer.

The thickness of the first layer can be between 2 and 10 mm, that of the second between 30 μm and 2 mm and that of binder (according to the first form of the invention) between 20 μm and 100 μm and between 40 μm and 1 mm (according to the second form). With regard to tanks, the total thickness is usually between 3 and 10 mm.

The compositions of the various layers are produced by mixing in the molten state the various constituents according to the usual techniques of thermoplastics. Optionally, the various solid additives (carbon black) are added to this mixture in the molten state.

The different layers of the structure of the invention, including the binder layers, can also contain at least one additive chosen from: - fillers (mineral, fire-resistant, etc.), fibers, dyes; pigments; brighteners; - antioxidants; UV stabilizers.

Claims

1 Structure successively comprising:

• a first layer of polyolefin,

A layer of binder based on hydrogenated ABC triblock copolymer,

• a second layer of fluoropolymer, in the triblock ABC copolymer, the three blocks A, B, and C are linked together in this order, each block being either a homopolymer or a copolymer obtained from two or more monomers, the block A being linked to block B and block B to block C by means of a covalent bond or an intermediate molecule linked to one of these blocks by a covalent bond and to the other block by another covalent bond , and such that:

- block A is compatible with the fluoropolymer, - block B is incompatible with the fluoropolymer and is incompatible with block A and it comprises hydrogenable double bonds,

- block C is incompatible with the fluoropolymer, block A and block B.

2 Structure according to claim 1 in which the binder layer is replaced by several layers comprising respectively:

An optional layer (L1) comprising (by weight) 50 to 95% of a fluoropolymer and 5 to 50% of a polymer (P1) essentially consisting of (meth) alkyl acrylate units,

A layer (L2) based on amino terminated polyamide,

3 Structure successively comprising: a first layer of polyolefin, • a second layer based on a mixture of hydrogenated triblock ABC copolymer and a fluoropolymer, in the ABC triblock copolymer, the three blocks A, B, and C are interconnected in this order, each block being either a homopolymer is a copolymer obtained from two or more monomers, block A being linked to block B and block B to block C by means of a covalent bond or an intermediate molecule linked to one of these blocks by a covalent bond and to the other block by another covalent bond, and such that:

- block C is incompatible with the fluoropolymer, block A and block B.

4 Structure according to any one of the preceding claims wherein the fluoropolymer is PVDF homopolymer.

5 devices for transferring or storing fluids made up of the structure according to any one of the preceding claims and in which the polyolefin is disposed outside.

6 devices for transferring or storing fluids consisting of the structure according to any one of claims 1 to 4 and in which the polyolefin is disposed inside.