阅读说明：本技术 对于生物汽油中的提取具有改善的抗性的多层管状结构体及其用途 (Multilayer tubular structure with improved resistance to extraction in biogasoline and use thereof ) 是由 T.蒙塔纳里 C.雷科奎尔 B.维尔鲍乌赫德 于 2017-01-12 设计创作，主要内容包括：本发明涉及用于输送流体、具体地汽油的多层管状结构体(MLT),其从最内到最外层包括至少一个内阻挡层(1)和位于所述阻挡层上方的至少一个外层(2),所述外层(2)或位于所述阻挡层上方的层(2)和任何其它层的组平均包含相对于所述层(2)的组成的总重量的0-5％的增塑剂,或位于所述阻挡层上方的外层的组平均包括0-5％的增塑剂,所述外层(2)主要包括至少一种脂族聚酰胺或由大于75％的脂族单元组成的聚酰胺,其中位于阻挡层上方的至少一个第二外层(2’)存在并且优选地位于层(2)的上方,所述层(2’)是增塑的,所述增塑剂特别地以相对于所述层的组成的总重量的1.5重量％-15重量％的比例存在,所述层(2’)的厚度优选地占管状结构体的总厚度的最高达20％、具体地最高达200μm。(The invention relates to a multilayer tubular structure (MLT) for transporting fluids, in particular gasoline, comprising, from the innermost to the outermost layer, at least one inner barrier layer (1) and at least one outer layer (2) located above said barrier layer, said outer layer (2) or group of layers (2) located above said barrier layer and any other layers comprising, on average, 0-5% of a plasticizer relative to the total weight of the composition of said layer (2) or group of outer layers located above said barrier layer comprising, on average, 0-5% of a plasticizer, said outer layer (2) comprising predominantly at least one aliphatic polyamide or a polyamide consisting of more than 75% of aliphatic units, wherein at least one second outer layer (2 ') located above the barrier layer is present and preferably located above the layer (2), said layer (2') being plasticized, said plasticizer being in particular present in a proportion of 1.5% to 15% by weight relative to the total weight of the composition of said layer The thickness of the layer (2') preferably amounts to up to 20%, in particular up to 200 μm, of the total thickness of the tubular structure.)

1. Multilayer tubular structure MLT intended for the transport of fuels, in particular gasoline, comprising, from the inside to the outside, at least one inner barrier layer (1) made of PPA and at least one outer layer (2) located above the barrier layer,

said outer layer (2) or all layers (2) and other optional layers above the barrier layer comprise on average 0-5% of a plasticizer, relative to the total weight of the composition of the layer (2), or wherein all outer layers above the barrier layer comprise on average 0-5% of a plasticizer,

the outer layer (2) essentially comprises at least one polyamide of aliphatic type or consisting of more than 75% of aliphatic units, chosen from:

-has the formula C_AThe polyamide denoted A having an average number of carbon atoms per nitrogen atom of from 4 to 8.5, advantageously from 4 to 7;

-has the formula C_BThe polyamide noted B having an average number of carbon atoms per nitrogen atom of from 7 to 10, advantageously from 7.5 to 9.5;

-has the formula C_CThe polyamide noted C having an average number of carbon atoms per nitrogen atom of from 9 to 18, advantageously from 10 to 18;

with the proviso that when the outer layer (2) comprises at least three polyamides, at least one of the polyamides A, B and C is excluded,

wherein at least one second outer layer (2 ') is present above the barrier layer and preferably above the layer (2), said layer (2 ') being plasticized, said plasticizer being present in particular in a proportion of 1.5% to 15% by weight relative to the total weight of the composition of the layer, the thickness of the layer (2 ') preferably representing up to 20%, in particular up to 200 μm, of the total thickness of the tubular structure.

2. The multilayer tubular structure (MLT) according to claim 1, wherein the outer layer (2) comprises 0-1.5% of a plasticizer, relative to the total weight of the composition of the layer (2).

3. The multilayer tubular structure (MLT) according to claim 1 or 2, wherein layer (2') is the outermost layer and is the only plasticized layer, layer (2) not comprising a plasticizer.

4. Multilayer tubular structure (MLT) according to one of claims 1-3, wherein at least one layer (3) is present, said layer (3) comprising not more than 15% by weight of plasticizer, preferably not more than 1.5% by weight of plasticizer, the stratum (3) advantageously comprising no plasticizer relative to the total weight of the ingredients of the layer (3),

said layer (3) essentially comprising at least one polyamide of aliphatic type or consisting of more than 75% of aliphatic units, said aliphatic polyamide being chosen from:

-has the formula C_AThe polyamide denoted A having an average number of carbon atoms per nitrogen atom of from 4 to 8.5, advantageously from 4 to 7;

-has the formula C_BThe polyamide noted B having an average number of carbon atoms per nitrogen atom of from 7 to 10, advantageously from 7.5 to 9.5;

-has the formula C_CThe polyamide noted C having an average number of carbon atoms per nitrogen atom of from 9 to 18, advantageously from 10 to 18;

with the proviso that when said layer (3) comprises at least three polyamides, at least one of said polyamides A, B and C is excluded,

the layer (3) is located between the outer layer (2) and the barrier layer (1);

or the layer (3) is an adhesive layer, the thickness of which is up to 15% of the structure (MLT).

5. Multilayer tubular structure (MLT) according to any one of claims 1 to 4, wherein the polyamide of the outer layer (2) is a fully aliphatic polyamide.

6. Multilayer tubular structure (MLT) according to one of claims 1 to 5, wherein the polyamide of the outer layer (2) is a polyamide selected from the group consisting of: b or C as defined in claim 1, in particular PA11, PA12, PA610, PA612 or PA1012, the corresponding copolyamide and the polyamide or mixture of copolyamides, the polyamide obtained from the lactam being advantageously washed.

7. Multilayer tubular structure (MLT) according to one of the claims 1 to 6, wherein the PPA of the barrier layer (1) is electrically conductive.

8. Multilayer tubular structure (MLT) according to one of claims 4-7, wherein the polyamide of layer (3) is selected from binary mixtures: PA6 and PA12, PA6 and PA612, PA6 and PA610, PA12 and PA612, PA12 and PA610, PA1010 and PA612, PA1010 and PA610, PA1012 and PA612, PA1012 and PA 610; and ternary mixtures: PA6, PA610 and PA12, PA6, PA612 and PA12, PA6, PA614 and PA 12.

9. Multilayer tubular structure (MLT) according to one of claims 4 to 8, wherein at least one of the layers (2) or (3) comprises at least one impact modifier and/or at least one additive.

10. Multilayer tubular structure (MLT) according to one of claims 1 to 9, wherein the structure comprises two layers in the following order: (2) /(1), the layer (2) comprises not more than 1.5 wt% of a plasticizer, relative to the total weight of the composition of the respective layer, in particular the formation (2) does not comprise a plasticizer.

11. Multilayer tubular structure (MLT) according to one of claims 1 to 10, wherein the structure comprises three layers in the following order: (2 ')/(2)/(1), the layer (2') being as defined in claim 2, the layer (2) comprising not more than 1.5 wt% of a plasticizer relative to the total weight of the composition of the layers, in particular the formation (2) comprising no plasticizer.

12. Multilayer tubular structure (MLT) according to one of claims 4 to 11, wherein the structure comprises three layers in the following order:

(2) /(3)/(1), layer (3) includes a plasticizer, or layer (3) does not include a plasticizer when it is different from the adhesive layer.

13. Multilayer tubular structure (MLT) according to one of claims 4 to 12, wherein the structure comprises the following layers in the following order:

(2')/(2)/(3)/(1), layer (3) includes a plasticizer, or layer (3) does not include a plasticizer.

14. Use of the multilayer tubular structure MLT as defined in one of claims 1 to 13 for the transport of fuels, in particular gasoline.

15. Use of the multilayer tubular structure MLT as defined in one of claims 1 to 13 for complying with the extractables test, in particular in that: filling said multilayer tubular structure MLT with an alcohol-containing gasoline of the FAM B type, and heating all the material at 60 ℃ for 96 hours, then emptying it into a beaker by filtration, then evaporating the filtrate of the beaker at room temperature, and finally weighing the residue, the proportion of which must be less than or equal to 6g/m²The internal surface area of the tube.

Technical Field

The present invention relates to a multilayer structure, in particular in the form of a tube, and to the use thereof for transporting fluids, in particular gasohol-type fuels, in particular gasohol, in particular for motor vehicles.

The invention relates more particularly to the presence of a tube in an engine. These pipes may be intended, for example, for conveying fuel (in particular between the tank and the engine), for cooling circuits, for hydraulic systems, or for air-conditioning circuits or for conveying urea/water mixtures.

Background

For the transport of gasoline and in particular bio-gasoline, a number of criteria must be met, in particular good barrier (insulating) properties (for environmental reasons), cold shock, pressure resistance, etc.

For safety and environmental protection reasons, in particular in the presence of new biofuels, the car manufacturers are demanding special mechanical characteristics for the above-mentioned pipes, as well as characteristics of very low permeability and good resistance to the different components of the fuel (which vary depending on the country) (hydrocarbons, additives, alcohols such as methanol and ethanol, which may in some cases be the main component), engine lubricating oils and other chemical products liable to be encountered in this environment (battery acids, brake fluids, cooling fluids, metal salts such as chlorides of zinc or calcium).

The specification characteristics generally required by automotive manufacturers for pipes, considered satisfactory, are summarized below:

-if the pipe is a multi-layer pipe, a good, continuous adhesion (adhesion) between the layers, most particularly after it has been exposed to fuel;

good integrity of the connection (pipe with joint) after circulation of the fuel, i.e. without causing any leakage;

good dimensional stability of the tube when it is used with gasoline;

good impact resistance in cold conditions (about-30 ℃ to-40 ℃) so that the tube does not break;

good heat resistance (about 150 ℃), so that the tube does not deform;

good resistance to ageing in hot oxidizing media (for example: hot air from the engine compartment at about 100 ℃. about.150 ℃);

good resistance to fuels and their degradation products and in particular with a high peroxide content;

very low permeability to fuel, and more specifically good barrier properties to biofuel (both for its polar components (e.g. ethanol) and for its non-polar components (hydrocarbons));

good flexibility of the tube, in particular of the fuel supply conduit, facilitating assembly;

good for ZnCl₂(e.g. the outside of the pipe is exposed to the environment when the road has been sanded in winter).

Moreover, the required tube must avoid the following drawbacks:

-delamination of layers, in particular of inner layers, in particular during the insertion of the joint (which may lead to leakage) if the pipe is a multilayer pipe;

excessive swelling (expansion) of the pipe after ageing in gasoline/diesel systems (including for biodiesel or bio-gasoline), which can lead to problems of leakage or of positioning under the vehicle.

Recently, a new problem has arisen, namely the excess of extractables from the multilayer tube after prolonged contact with alcohol-containing gasoline. The extractable material tends to clog or clog the nozzles of the vehicle engine. Therefore, automobile manufacturers, in particular the public (Volkswagen), have established new standards for selecting pipes capable of delivering gasoline, in particular alcohol-containing gasoline, in motor vehicles which are more stringent than they have been. A new test developed by different manufacturers, in particular by the public, therefore consists in determining the proportion of extractables of a gasoline delivery pipe after bringing the inside of said pipe into contact with hot alcohol-containing gasoline for several hours and weighing the evaporation residue of the gasoline contained in said pipe (corresponding to the extractables). If the proportion of extractables is as low as possible, in particular less than or equal to 6g/m²(internal surface area of the tube), the tube tested may therefore be most suitable for transporting gasoline.

Currently, there are two types of tubes: single-layer pipes and multi-layer pipes, i.e. consisting of one or more polymer layers. In particular, for the transport of gasoline, the use of multilayer pipes comprising a barrier layer is tending to become widespread for ecological reasons.

Conventionally, according to the conventional technique for deforming thermoplastics, the tube used is made as follows: by single extrusion if it is a single-layer tube or by co-extrusion of the different layers if it is a multi-layer tube.

Structures for transporting gasoline (MLT) are typically composed of: a barrier layer such as PPA, which has a PA layer (at least one layer) on top, and optionally includes an adhesive layer if adhesion between the other layers proves insufficient.

Thus, patent EP 2098580 describes in particular a tube with a PPA barrier and at least one layer of plasticized or unplasticized polyamide above the barrier layer.

Nevertheless, this type of structure, as well as other MLTs known to those skilled in the art, is no longer suitable for the above-described new tests for extractables.

Disclosure of Invention

The present invention aims to solve this new problem by means of a specific arrangement and composition of the layers of the multilayer structure.

The invention relates to a multilayer tubular structure MLT intended for transporting fluids, in particular gasoline, comprising, from the inside to the outside: at least one inner barrier layer (1) and at least one outer layer (2) located above the barrier layer,

the outer layer (2), or all layers (2) and other optional layers above the barrier layer, comprise on average 0-5% of a plasticizer, relative to the total weight of the composition of the layer (2), or wherein all outer layers above the barrier layer comprise on average 0-5% of a plasticizer,

the outer layer (2) essentially comprises at least one polyamide of aliphatic type or consisting of more than 75% of aliphatic units, chosen from:

-has the formula C_AThe polyamide denoted A having an average number of carbon atoms per nitrogen atom of from 4 to 8.5, advantageously from 4 to 7;

-has the formula C_BThe polyamide noted B having an average number of carbon atoms per nitrogen atom of from 7 to 10, advantageously from 7.5 to 9.5;

-has the formula C_CThe polyamide noted C having an average number of carbon atoms per nitrogen atom of from 9 to 18, advantageously from 10 to 18;

with the proviso that when the outer layer (2) comprises at least three polyamides, at least one of the polyamides A, B and C is excluded (excluding at least one of the polyamides A, B and C).

If the subject matter intended for the delivery of fluids is also used for the storage of fluids, it will not depart from the scope of the present invention.

The term "fluid" means a gas or liquid, in particular a liquid, and in particular an oil, a brake fluid, a urea solution, a glycol-based coolant, a fuel, in particular a light fuel liable to contamination, advantageously a fuel other than diesel, in particular gasoline or LPG, in particular gasoline, and more particularly gasohol, used in motor vehicles.

Advantageously, said fluid refers to a fuel, in particular a gasoline and more particularly a gasohol.

Air, nitrogen and oxygen are excluded from the definition of the gas.

The term "gasoline" refers to a mixture of hydrocarbons resulting from the distillation of petroleum to which additives or alcohols such as methanol or ethanol, which may be the major component in some cases, may be added.

The expression "alcohol-containing gasoline" refers to gasoline to which methanol or ethanol has been added. It also refers to a gasoline of type E95, which does not contain any petroleum distillation products.

The expression "barrier layer" refers to a layer having the characteristics of low permeability and good resistance to various constituents of a fluid, in particular a fuel, i.e. it slows down the passage of a fluid, in particular a fuel (both in terms of its polar components (e.g. ethanol) and its non-polar components (hydrocarbons)) to other layers of the structure or even to the outside of the structure. Thus, the barrier layer is a layer that: it must above all not allow too much gasoline to be lost to the atmosphere by diffusion, so that atmospheric pollution can be avoided.

According to the gravimetric method with CE 10: isooctane/toluene/ethanol-45/45/10 vol% permeability to gasoline was measured at 60 ℃.

The transient permeability is zero during the induction period (lead-in period), then it gradually increases under continuous operating conditions up to an equilibrium value, which corresponds to the permeability value. This value obtained under continuous operating conditions is taken as the permeability of the material.

These barrier materials may be polyphthalamides (polyphthalamides) and/or functionalized fluorine-containing materials, such as functionalized copolymers of Ethylene and Tetrafluoroethylene (ETFE), functionalized copolymers of ethylene, tetrafluoroethylene and hexafluoropropylene (EFEP), copolymers of tetrafluoroethylene-perfluoro (alkyl vinyl ether) -Chlorotrifluoroethylene (CPT). If these polymers are not functionalized, an intermediate adhesive layer may be added to ensure good adhesion within the MLT structure.

Among PPAs, coPA6T, PA9T and copolymers thereof, PA10T and copolymers thereof, MXD6 and copolymers thereof are particularly advantageous.

The expression "the outer layer (2) mainly comprises at least one aliphatic polyamide" means that the aliphatic polyamide is present in the layer (2) in a proportion of more than 50% by weight. Aliphatic polyamides are linear and not cycloaliphatic.

Advantageously, the predominantly aliphatic polyamide of the layer (2) also predominantly comprises aliphatic units, i.e. more than 50% of aliphatic units.

Advantageously, the predominantly aliphatic polyamide of the layer (2) comprises more than 75% of aliphatic units; preferably, the predominantly aliphatic polyamide of the layer (2) is completely aliphatic.

The inventors have thus found that the absence or at least (at least) small proportion of plasticizer in the outer layer (i.e. the layer located above the barrier layer) makes it possible to greatly reduce the proportion of extractables as determined by the test as defined above, and in particular by the test consisting in: the tubular structure is filled with an alcohol-containing gasoline of the FAM B type and all the material is heated at 60 ℃ for 96 hours, then emptied into a beaker by filtering it, the filtrate of the beaker is then evaporated at room temperature, and finally the residue is weighed, the proportion of which must be less than or equal to about 6g/m2 of the internal surface area of the tube.

Gasoline containing alcohols FAM B is described in standard DIN 51604-1: 1982. DIN 51604-2: 1984 and DIN 51604-3: 1984.

Briefly, gasoline-containing FAM a was first prepared as a mixture of 50% toluene, 30% isooctane, 15% diisobutylene, and 5% ethanol, and FAM B was then prepared by mixing 84.5% FAM a with 15% methanol and 0.5% water.

FAM B consisted of 42.3% toluene, 25.4% isooctane, 12.7% diisobutylene, 4.2% ethanol, 15% methanol, and 0.5% water in total.

According to the present application, the term "polyamide", also called "PA", covers:

-a homopolymer,

copolymers or copolyamides based on a plurality of amide units, for example copolyamide 6/12 having amide units derived from lactam 6 and lactam 12,

alloys of polyamides, as long as the polyamide is the main component.

In a broad sense, there is also a class of copolyamides which, although not preferred, form part of the scope of the present invention. They are copolyamides comprising not only amide units (which will be predominant and therefore in fact they are to be considered as copolyamides in a broad sense) but also units which are not amides in nature, for example ether units. The most well known examples are PEBA or polyether-block-amides, and copolyamide-ester-ether, copolyamide-ether and copolyamide-ester variants thereof. Among these, reference will be made to PEBA-12 in which the polyamide units are identical to those of PA12 and to PEBA-6.12 in which the polyamide units are identical to those of PA 6.12.

In the case of the recognition that there are as many nitrogen atoms as there are amide groups (-CO-NH-), homopolyamides, copolyamides and alloys are also distinguished from each other by the number of carbon atoms per nitrogen atom.

The polyamide having a high carbon content is a polyamide having a high carbon atom (C) content relative to a nitrogen atom (N). These are polyamides having about at least 9 carbon atoms per nitrogen atom, such as polyamide-9, polyamide-12, polyamide-11, polyamide-10.10 (PA10.10), copolyamide 12/10.T, copolyamide 11/10.T, polyamide-12. T and polyamide-6.12 (PA 6.12). T represents terephthalic acid.

The nomenclature used to define polyamides is described in standard ISO 1874-1: 1992 "Plastics-Polyamides (PA) molding and extrusion materials-Part 1: designation ", in particular on page 3 (tables 1 and 2), and is well known to the person skilled in the art.

The polyamide having a low carbon content is a polyamide having a low carbon atom (C) content relative to a nitrogen atom (N). These are polyamides having about less than 9 atoms per nitrogen atom, such as polyamide-6, polyamide-6.6, polyamide-4.6, copolyamide-6. T/6.6, copolyamide 6.I/6.6, copolyamide 6.T/6.I/6.6 and polyamide 9. T. I represents isophthalic acid.

In the case of homopolyamides of the PA-X.Y type (where X denotes a unit derived from a diamine and Y denotes a unit derived from a diacid), the number of carbon atoms per nitrogen atom is the average of the number of carbon atoms present in the unit X derived from a diamine and in the unit Y derived from a diacid. Thus, PA6.12 is a PA with 9 carbon atoms per nitrogen atom, i.e., C9 PA. PA6.13 is C9.5.

In the case of copolyamides, the number of carbon atoms per nitrogen atom is calculated according to the same rule. The calculation is carried out on the basis of the molar proportions of the various amide units. In the case of copolyamides having non-amide-type units, the calculation is carried out only on the portion of the amide units. Thus, for example, for PEBA-12, which is a block copolymer of 12 amide units and ether units, the average number of carbon atoms per nitrogen atom will be 12, as for PA 12; for PEBA-6.12, it will be 9, as for PA 6.12.

Thus, polyamides with high carbon content, such as polyamide PA12 or 11, adhere with difficulty to (co) PAXT with low carbon content, such as coPA6T, polyamides with low carbon content, such as polyamide PA6, or alloys of polyamide PA6 and polyolefins (such as those sold by Arkema)

)。

Nevertheless, it was observed that the tubular structures proposed so far are not satisfactory for applications intended for biofuels, since the requirements of the automotive manufacturer specifications recalled above cannot be met all at the same time.

Biofuels are not derived solely from petroleum and include a (certain) proportion of polar products such as at least 3% of plant-derived alcohols, e.g. ethanol or methanol. This content may be as high as 85% or even 95%.

In addition, the circulation temperature of the fuel tends to rise due to new engines (more closed, running at higher temperatures).

Advantageously, the invention relates to a multilayer tubular structure (MLT) as defined above, wherein said outer layer (2) comprises from 0 to 1.5% of a plasticizer, relative to the total weight of the composition of said layer (2).

In the case of the presence of several (several) layers (2), it is possible for one of the outer layers to have a greater proportion of plasticizer, for example 15% by weight, but in this case the proportion of plasticizer is compensated by the thickness of the layer, which is then much thinner, so that the average of the plasticizer present in all outer layers does not exceed 5%. The proportion of plasticizer in this layer can then be up to 15%, but its thickness does not exceed 20% of the total thickness of the tube; preferably, it does not exceed 200 μm.

Advantageously, the invention relates to a multilayer tubular structure (MLT) comprising a layer (2) as defined above, wherein there is at least one second outer layer (2 ') located above the barrier layer and which is preferably located above said layer (2), said layer (2 ') being plasticized, said plasticizer being in particular present in a proportion of 1.5% to 15% by weight relative to the total weight of the composition of said layer, the thickness of said layer (2 ') preferably representing up to 20%, in particular up to 200 μm, of the total thickness of said tubular structure.

As with layer (2), layer (2 ') comprises predominantly aliphatic polyamide, i.e. the aliphatic polyamide is present in layer (2') in a proportion of more than 50% by weight. The aliphatic polyamide is linear and not cycloaliphatic.

Advantageously, the predominantly aliphatic polyamide of the layer (2') also comprises predominantly aliphatic units, i.e. more than 50% of aliphatic units.

Advantageously, the predominantly aliphatic polyamide of the layer (2') comprises more than 75% of aliphatic units; preferably, the predominantly aliphatic polyamide of the layer (2') is completely aliphatic.

In another embodiment, the invention relates to a multilayer tubular structure (MLT), wherein one or more layers (2) comprise up to 1.5% by weight of plasticizer, relative to the total weight of the composition of said one layer or all the compositions of the layers (2).

Advantageously, the multilayer tubular structure (MLT) comprises a single layer (2) and does not comprise a plasticizer.

In another embodiment, the invention relates to a multilayer tubular structure (MLT), wherein the plasticizer content of all layers located above the barrier layer is at most 5% by weight, relative to the total weight of the composition of all layers located above the barrier layer.

In another embodiment, the invention relates to a multilayer tubular structure (MLT) wherein layer (2') is the outermost and the only plasticized layer, layer (2) not comprising a plasticizer.

The proportion of plasticizer may represent up to 15% by weight of the total weight of the composition of the layer (2'). The larger the proportion of plasticizer, the thinner the layer (2 ') will be, wherein the thickness of the layer (2') preferably amounts to up to 20%, in particular up to 200 μm, of the total thickness of the tubular structure.

Advantageously, the multilayer tubular structure (MLT) consists of three layers (2')/(2)/(1) from the outside to the inside: the layer (2') is the only plasticized layer, the layer (2) not containing a plasticizer in the proportions defined above.

The multilayer tubular structure (MLT) consisting of three layers (2')/(2)/(1) from the outside to the inside has the following advantages: the elongation at break at very low humidity at t ═ 0 and at relative humidity between 0 and 30% when the structure is very dry is very good and in particular better than for structures in which the layers (2') and (2) do not contain a plasticizer.

Advantageously, in the latter embodiment, said layer (2') is the outermost layer and the polyamide of the latter is a long-chain polyamide, i.e. the average number of carbon atoms per nitrogen atom, denoted Cc, is from 9.5 to 18; the layer (2) is located between the barrier layer and the layer (2') and the polyamide of the layer (2) is a short chain polyamide, i.e. the average number of carbon atoms per nitrogen atom, noted Ca, is 4-9.

Advantageously, in the latter embodiment, in the case of a thickness of said layer (2') of 100-.

Advantageously, in the latter embodiment, said layer (2') is the outermost layer and the polyamide of the latter is a long-chain polyamide, i.e. the average number of carbon atoms per nitrogen atom, denoted Cc, is from 9.5 to 18; the layer (2) is located between the barrier layer and the layer (2 ') and the polyamide of the layer (2) is a short-chain polyamide, i.e. the average number of carbon atoms per nitrogen atom, denoted Ca, is 4-9, in the case of a thickness of the layer (2') of 100-200 μm, the layer (2) has a thickness of at least 200-400 μm and the layer (1) has a thickness of 100-300 μm.

Regardless of the number of layers, a preferred tubular structure is one that contains as little plasticizer as possible in the outer layer, i.e., the layer furthest from the fluid. These structures may be the following:

-a multilayer tubular structure (MLT) comprising not more than 1.5% of plasticizer in the first 50% of its thickness, starting from the barrier layer in contact with the fluid.

-a multilayer tubular structure (MLT) comprising not more than 1.5% plasticizer in the first 75% of its thickness starting from the barrier layer in contact with the fluid.

-a multilayer tubular structure (MLT) comprising not more than 1.5% plasticizer in the first 85% of its thickness starting from the barrier layer in contact with the fluid.

-a multilayer tubular structure (MLT) comprising no plasticizer in the first 50% of its thickness starting from the barrier layer in contact with the fluid.

-a multilayer tubular structure (MLT) comprising no plasticizer in the first 75% of its thickness starting from the barrier layer in contact with the fluid.

-a multilayer tubular structure (MLT) comprising no plasticizer in the first 85% of its thickness starting from the barrier layer in contact with the fluid.

In another embodiment, the invention relates to a multilayer tubular structure (MLT) as defined above, wherein at least one layer (3) is present, said layer (3) comprising not more than 15% by weight of plasticizer, preferably not more than 1.5% by weight of plasticizer, relative to the total weight of the constituents of said layer (3); advantageously, said layer (3) does not comprise a plasticizer, said layer (3) comprising essentially at least one polyamide of aliphatic type or consisting of more than 75% of aliphatic units, said aliphatic polyamide being chosen from:

-a polyamide denoted a having an average number of carbon atoms per nitrogen atom denoted CA from 4 to 8.5, advantageously from 4 to 7;

polyamides noted B having an average number of carbon atoms per nitrogen atom noted CB of from 7 to 10, advantageously from 7.5 to 9.5;

-a polyamide denoted C having an average number of carbon atoms per nitrogen atom denoted CC ranging from 9 to 18, advantageously from 10 to 18;

with the proviso that when said layer (3) comprises at least three polyamides, at least one of said polyamides A, B and C is excluded,

said layer (3) being located between said outer layer (2) and said barrier layer (1);

or the layer (3) is an adhesive layer whose thickness represents up to 15% of the structure (MLT).

Said layer (3), when it is not an adhesive layer, is an aliphatic polyamide as defined for said layers (2) and (2').

Advantageously, the tubular structure of the invention is a three-layer structure consisting of the following layers from the outside to the inside: (2) /(3)/(1), the layer (2) is plasticized up to 5% as described above and is thin, and the layer (3) does not contain a plasticizer when it is different from the adhesive layer as defined above.

Nevertheless, the layer (2) plasticized up to 5% by weight must not be too thin, otherwise the barrier layer is not sufficiently central and the MLT structure risks not being good enough in terms of impact. On the other hand, if there is an additional thick (non-plasticized) layer between the layer (2) and the layer (1) such that the layer (1) is not too off-center, it can be very thin.

Additional layers (2') may also be present in the three-layer structure.

The layer (3) may also be an adhesive, as described in particular in patents EP 1452307 and EP1162061, EP1216826 and EP 0428833.

Implicitly (inherently) the layers (2) and (1) adhere to each other. The adhesive layer is intended to be interposed between two layers that do not stick or adhere with difficulty to each other.

The adhesive may be, for example, but not limited to, a composition based on 50% Mn 16000 copolyamide 6/12(70/30 wt%) and 50% Mn 16000 copolyamide 6/12(30/70 wt%), a composition based on PP (polypropylene) grafted with maleic anhydride known under the name Admer QF551A of Mitsui, a composition based on PA610(Mn 30000, and as defined elsewhere) and 36% PA6(Mn 28000) and 1.2% organic stabilizers (consisting of 0.8% of phenol Lowinox44B25 from Great Lakes, 0.2% of phosphite Irgafos 168 from Ciba, 0.2% of UV stabilizer Tinuvin 312 from Ciba), a composition based on PA612(Mn 00, and as defined elsewhere) and 36% PA6(Mn 28000, and as defined elsewhere) and 1.2% of stabilizer Tinuvin 312 from Ciba 2900.8% of phenol from large Lakes 2900.8% of organic stabilizers 3644B 3644 from Great Lakes, 25 0.2% of a composition of the UV stabilizer Tinuvin 312 from Ciba) based on PA610(Mn 30000, and as defined elsewhere) and 36% of PA12(Mn 35000, and as defined elsewhere) and 1.2% of an organic stabilizer (consisting of 0.8% of phenol lowino 44B25 from Great Lakes, 0.2% of Irgafos 168 from Ciba, 0.2% of UV stabilizer Tinuvin 312 from Ciba), 40% of PA6(Mn 28000, and as defined elsewhere), 40% of PA12(Mn 28000, and as defined elsewhere) and 20% of a functionalized EPR Exxelor VA1801(Exxon) and 1.2% of an organic stabilizer (consisting of 0.8% of phenol lowino 44B from Great Lakes, 0.2% of irv2) based on PA 632% of a composition of Tinuvin 312, and 1.2% of an organic stabilizer (consisting of 0.8% of phenol lowino 25 from Ciba, irgavin 2) and 83% of a composition of Tinuvin 2% of a phosphite, and 2% of a stabilizer (Mn 3002) based on PA610, and 36% of a composition of phenol lowino 3, A composition of 40% PA6(Mn 28000, and as defined elsewhere) and 20% impact modifier of ethylene/ethyl acrylate/anhydride type (MFI 6 at 190 ℃ under 2.16 kg) in a weight ratio of 68.5/30/1.5 and 1.2% organic stabilizer (consisting of 0.8% of phenol Lowinox44B25 from Great Lakes, 0.2% of phosphite Irgafos 168 from Ciba, 0.2% of UV stabilizer Tinuvin 312 from Ciba).

In an advantageous embodiment, the invention relates to a multilayer tubular structure (MLT) as defined above, wherein the barrier layer (1) is a layer made of polyphthalamide (PPA) or fluoropolymer, in particular ETFE, EFEP or CPT type fluoropolymer.

The term PPA means the following ingredients: they are based predominantly on polyamides comprising a majority (majority) of units comprising at least one aromatic monomer, in particular polyphthalamides of the copolyamide type 6.T/x (where x refers to one or more comonomers), for example Zytel HTN from Dupont, for example Grivory HT from Ems, for example Amodels from Solvay, for example Genestars from Kuraray, said components being for example PPA components based on coPA6T/6I, coPA6T/66, coPA6T/6, coPA6T/6I/66, PPA9T, coPA 9T/x, PPA10T or coPA PPA 10T/x.

In an advantageous embodiment, the invention relates to a multilayer tubular structure (MLT) as defined above, wherein the barrier layer (1) is a layer made of polyphthalamide (PPA).

Advantageously, in the multilayer tubular structure (MLT) as defined above, the polyamide of the outer layer (2) is a polyamide chosen from: b or C as defined above, in particular PA11, PA12, PA610, PA612 or PA1012, the corresponding copolyamide and the polyamide or mixture of copolyamides, the polyamide obtained from the lactam being advantageously washed.

In another embodiment, the invention relates to a multilayer tubular structure (MLT) as defined below, wherein the PPA or fluoropolymer of the barrier layer (1) is electrically conductive.

Advantageously, in the multilayer tubular structure (MLT) as defined above, the polyamide of the layer (3) is a mixture of a polyamide having an average number of carbon atoms per nitrogen atom of 10 or more and a polyamide having an average number of carbon atoms per nitrogen atom of 6 or less, such as PA12 and PA6 and anhydride-functionalized (co) polyolefins.

Advantageously, in the multilayer tubular structure (MLT) as defined above, the polyamide of the layer (3) is chosen from binary mixtures: PA6 and PA12, PA6 and PA612, PA6 and PA610, PA12 and PA612, PA12 and PA610, PA1010 and PA612, PA1010 and PA610, PA1012 and PA612, PA1012 and PA 610; and ternary mixtures: PA6, PA610 and PA12, PA6, PA612 and PA12, PA6, PA614 and PA 12.

In another embodiment, the invention relates to a multilayer tubular structure (MLT) as defined above, wherein at least one of said layers (2), (2 ') and (3') comprises at least one impact modifier and/or at least one additive.

Of course, the impact modifier or the additive is not a plasticizer.

Advantageously, the layers (2) and (2') comprise at least one impact modifier and/or at least one additive.

Advantageously, the layers (2) and (3) comprise at least one impact modifier and/or at least one additive.

Advantageously, the layers (2), (2') and (3) comprise at least one impact modifier and/or at least one additive.

In another embodiment, the invention relates to a multilayer tubular structure (MLT) as defined above, wherein said structure comprises two layers in the following order: (2) /(1), said layer (2) comprising not more than 1.5 wt% of a plasticizer, relative to the total weight of the composition of the respective layer, in particular said layer (2) does not comprise a plasticizer.

In another embodiment, the invention relates to a multilayer tubular structure (MLT) as defined above, wherein said structure comprises three layers in the following order: (2 ')/(2)/(1), said layer (2') being as defined above, said layer (2) comprising not more than 1.5 wt% of plasticizer relative to the total weight of the composition of the respective layer, in particular said layer (2) comprising no plasticizer.

According to another embodiment, the invention relates to a multilayer tubular structure (MLT) as defined above, wherein said structure comprises, in the following order:

(2 ')/(2)/(3)/(1), wherein the layers (2) and (2') are as defined above, the layer (3) comprises not more than 1.5 wt. -% of a plasticizer relative to the total weight of the composition of the respective layer, the layer (3) comprises a plasticizer, or the layer (3) does not comprise a plasticizer.

In particular, the layer (2 ') of the above four-layer structure is plasticized, in particular present in a proportion of 1.5% to 15% by weight relative to the total weight of the composition of the layer, the thickness of the layer (2 ') preferably representing up to 20%, in particular up to 200 μm, of the total thickness of the tubular structure, in particular the layer (2 ') being the outermost and the only plasticized layer, the layer (2) not comprising a plasticizer.

According to another aspect, the invention relates to the use of a multilayer tubular structure MLT as defined above for transporting fuel, in particular gasoline.

According to another aspect, the invention relates to the use of a multilayer tubular structure MLT as defined above for complying with the extractables test, in particular in that: the multilayer tubular structure MLT is filled with an alcohol-containing gasoline of the FAM B type and all the material is heated at 60 ℃ for 96 hours, then emptied into a beaker by filtration, the filtrate of the beaker is then evaporated at room temperature and finally the residue is weighed, the proportion of which must be less than or equal to 6g/m2 of the internal surface area of the tube.

All variants described for the multilayer tubular structure MLT apply herein to the use of the multilayer tubular structure MLT for complying with the extractables test.

Extractable values of less than or equal to about 6g/m2 tube internal surface area indicate that the proportion of extractable is very low and thus clogging of the nozzle will be avoided.

The invention also relates to the following:

item 1. multilayer tubular structure MLT intended for the transport of fuels, in particular gasoline, comprising, from the inside to the outside, at least one inner barrier layer (1) made of PPA and at least one outer layer (2) located above the barrier layer,

said outer layer (2) or all layers (2) and other optional layers above the barrier layer comprise on average 0-5% of a plasticizer, relative to the total weight of the composition of the layer (2), or wherein all outer layers above the barrier layer comprise on average 0-5% of a plasticizer,

the outer layer (2) essentially comprises at least one polyamide of aliphatic type or consisting of more than 75% of aliphatic units, chosen from:

-has the formula C_AThe polyamide denoted A having an average number of carbon atoms per nitrogen atom of from 4 to 8.5, advantageously from 4 to 7;

-has the formula C_BEach nitrogen atom ofA polyamide noted B having a mean number of moles ranging from 7 to 10, advantageously from 7.5 to 9.5;

-has the formula C_CThe polyamide noted C having an average number of carbon atoms per nitrogen atom of from 9 to 18, advantageously from 10 to 18;

with the proviso that when the outer layer (2) comprises at least three polyamides, at least one of the polyamides A, B and C is excluded.

Item 2. the multilayer tubular structure (MLT) according to item 1, wherein the outer layer (2) comprises 0-1.5% of a plasticizer, relative to the total weight of the composition of the layer (2).

Item 3. the multilayer tubular structure (MLT) according to item 1 or 2, wherein at least one second outer layer (2 ') located above the barrier layer is present and preferably located above the layer (2), said layer (2 ') being plasticized, said plasticizer being in particular present in a proportion of 1.5% to 15% by weight relative to the total weight of the composition of said layer, the thickness of said layer (2 ') preferably representing up to 20%, in particular up to 200 μ ι η, of the total thickness of the tubular structure.

Item 4. the multilayer tubular structure (MLT) according to item 3, wherein layer (2') is the outermost layer and is the only plasticized layer, layer (2) not comprising a plasticizer.

Item 5. the multilayer tubular structure (MLT) according to one of items 1 to 4, wherein at least one layer (3) is present, said layer (3) comprising not more than 15 wt% of plasticizer, preferably not more than 1.5 wt% of plasticizer, the stratum (3) advantageously comprising no plasticizer relative to the total weight of the ingredients of the layer (3),

said layer (3) essentially comprising at least one polyamide of aliphatic type or consisting of more than 75% of aliphatic units, said aliphatic polyamide being chosen from:

-has the formula C_AThe polyamide denoted A having an average number of carbon atoms per nitrogen atom of from 4 to 8.5, advantageously from 4 to 7;

-has the formula C_BThe polyamide noted B having an average number of carbon atoms per nitrogen atom of from 7 to 10, advantageously from 7.5 to 9.5;

-has the formula C_CHas an average number of carbon atoms per nitrogen atom of 9 to 18Advantageously 10 to 18 of the polyamide noted C;

with the proviso that when said layer (3) comprises at least three polyamides, at least one of said polyamides A, B and C is excluded,

the layer (3) is located between the outer layer (2) and the barrier layer (1);

or the layer (3) is an adhesive layer, the thickness of which is up to 15% of the structure (MLT).

Item 6. the multilayer tubular structure (MLT) according to any of items 1 to 5, wherein the polyamide of the outer layer (2) is a fully aliphatic polyamide.

Item 7. the multilayer tubular structure (MLT) according to one of items 1 to 6, wherein the polyamide of the outer layer (2) is a polyamide selected from the group consisting of: b or C as defined in item 1, in particular PA11, PA12, PA610, PA612 or PA1012, the corresponding copolyamides and the polyamide or mixture of copolyamides, the polyamide obtained from the lactam being advantageously washed.

Item 8. the multilayer tubular structure (MLT) according to one of items 1 to 7, wherein the PPA of the barrier layer (1) is electrically conductive.

Item 9. the multilayer tubular structure (MLT) according to one of items 5 to 8, wherein the polyamide of layer (3) is selected from binary mixtures: PA6 and PA12, PA6 and PA612, PA6 and PA610, PA12 and PA612, PA12 and PA610, PA1010 and PA612, PA1010 and PA610, PA1012 and PA612, PA1012 and PA 610; and ternary mixtures: PA6, PA610 and PA12, PA6, PA612 and PA12, PA6, PA614 and PA 12.

Item 10. the multilayer tubular structure (MLT) according to one of items 5 to 9, wherein at least one of the layers (2) or (3) comprises at least one impact modifier and/or at least one additive.

Item 11. the multilayer tubular structure (MLT) according to one of items 1 to 10, wherein the structure comprises two layers in the following order: (2) /(1), the layer (2) comprises not more than 1.5 wt% of a plasticizer, relative to the total weight of the composition of the respective layer, in particular the formation (2) does not comprise a plasticizer.

Item 12. the multilayer tubular structure (MLT) according to one of items 3 to 11, wherein the structure comprises three layers in the following order: (2 ')/(2)/(1), the layer (2') being as defined in item 2, the layer (2) comprising not more than 1.5 wt% of a plasticizer relative to the total weight of the composition of the layers, in particular the formation (2) comprising no plasticizer.

Item 13. the multilayer tubular structure (MLT) according to one of items 5 to 12, wherein the structure comprises three layers in the following order:

(2) /(3)/(1), layer (3) includes a plasticizer, or layer (3) does not include a plasticizer when it is different from the adhesive layer.

Item 14. the multilayer tubular structure (MLT) according to one of items 5 to 13, wherein the structure comprises the following layers in the following order:

(2')/(2)/(3)/(1), layer (3) includes a plasticizer, or layer (3) does not include a plasticizer.

Item 15 use of the multilayer tubular structure MLT as defined in one of items 1 to 14 for transporting fuel, in particular gasoline.

Item 16 use of the multilayer tubular structure MLT as defined in one of items 1 to 14 for complying with the extractables test, in particular in that: filling said multilayer tubular structure MLT with an alcohol-containing gasoline of the FAM B type, and heating all the material at 60 ℃ for 96 hours, then emptying it into a beaker by filtration, then evaporating the filtrate of the beaker at room temperature, and finally weighing the residue, the proportion of which must be less than or equal to 6g/m²The internal surface area of the tube.

Detailed Description