Multilayer combining both good ageing properties and resistance to bursting in hot conditions, that can be used for high-temperature motor vehicle applications

Abstract

The present invention concerns a multilayer tubular structure (MLT) intended for transporting fluids such as air, oil, water, a urea solution, a cooling liquid made from glycol, a transmission oil cooler (TOC), or an air conditioning liquid, or a fuel such as petrol, in particular bio-petrol, or diesel, in particular bio-diesel, comprising at least one layer (1) and at least one layer (2), said layer (1) comprising a composition comprising: -a) at least 50% by weight of at least one semi-aromatic polyamide of formula W/ZT, -b) at least 10% by weight, preferably at least 15%, of an impact modifier, -c) between 0 and 20% by weight of at least once plasticiser, -d) between 0 and 40% by weight of at least one additive, the sum of a) +b) +c) +d) being equal to 100%, said layer (2) comprising a composition comprising a) at least 50% by weight of at least one short-chain semi-crystalline polyamide referred to as (A), said short-chain aliphatic polyamide (A) being of formula X Y/Z, or formula V/Z, -b) between 0 and 15% of at least one impact modifier, -c) between 0 and 12% by weight of at least once plasticiser, -d) between 0 and 40% by weight of at least one additive, the sum a)+b)+c)+d) being equal to 100%.

Claims

1. A multilayer tubular (MLT) structure intended for transporting fluids including air, oil, water, a urea solution, a cooling liquid made from glycol, a transmission oil cooler (TOC), an air-conditioning liquid, or a fuel, petrol, bio-petrol, and diesel, comprising a least one layer (1) and at least one layer (2), said layer (1) comprising a composition comprising: a) at least 50% by weight of at least one semi-aromatic polyamide of formula W/ZT wherein: W is a repeating aliphatic unit selected from a unit obtained from the polycondensation of at least one C.sub.4-C.sub.36 aminocarboxylic acid, a unit obtained from the polycondensation of at least one C.sub.4-C.sub.36 lactam, and an aliphatic repeating unit X.Y obtained from the polycondensation: of at least one diamine X, said diamine being selected from a linear or branched aliphatic diamine or a mixture thereof, and at least one dicarboxylic acid Y, said diacid being an aliphatic diacid, said diamine and said diacid comprising from 4 to 36 carbon atoms, the molar proportion of W being from 0.3 to 1.1 for 1 mole of ZT, ZT is a repeating unit obtained from the polycondensation of at least one linear or branched aliphatic diamine (Z) comprising from 9 to 18 carbon atoms, with terephthalic acid (T), b) at least 10% by weight of an impact modifier, c) from 0 to 20% by weight of at least one plasticiser, d) from 0 to 40% by weight of at least one additive, the sum a)+b)+c)+d) being equal to 100%, said layer (2) comprising a composition comprising: a) at least 50% by weight of at least one short-chain semi-crystalline polyamide denoted (A) constituted of at least 70% aliphatic units and having an average number of carbon atoms per nitrogen atom denoted C.sub.A ranging from 4 to 9.5, said short-chain aliphatic polyamide (A) being: of formula X.sub.1Y.sub.1/Z.sub.1, wherein: X.sub.1Y.sub.1 is a repeating aliphatic unit obtained from the polycondensation of at least one linear or branched aliphatic diamine X.sub.1 comprising from 2 to 6 carbon atoms, with at least one aliphatic dicarboxylic acid Y.sub.1 comprising from 2 to 12 carbon atoms, Z.sub.1 is at least one optional polyamide repeating unit, Z.sub.1 being present at up to 30% by weight relative to the total weight X.sub.1Y.sub.1/Z.sub.1, or of formula V/Z.sub.1, V being a repeating unit obtained from the polycondensation of at least one lactam comprising from 2 to 8 carbon atoms, or at least one aminocarboxylic acid comprising from 2 to 8 carbon atoms, Z.sub.1 being as defined above in a), b) from 0 to 15% of at least one impact modifier, c) from 0 to 12% by weight of at least one plasticiser, d) from 0 to 40% by weight of at least one additive, the sum a)+b)+c)+d) being equal to 100%.

2. The multilayer tubular structure (MLT) according to claim 1, wherein the semi-aromatic polyamide of layer (1) has a Tm of from 230 C. to 285 C., measured according to ISO standard 11357-3:2013.

3. The multilayer tubular structure (MLT) according to claim 1, wherein the semi-aromatic polyamide of layer (1) is selected from the group consisting of PA 11/10T, PA 12/10T, PA 1010/10T, PA 1012/10T, PA 1212/10T, PA 610/10T, PA612/10T, PA 11/12T, PA 12/12T, PA 1010/12T, PA 1012/12T, PA 1212/12T, PA 610/12T and PA612/12T.

4. The multilayer tubular structure (MLT) according to claim 1, wherein the short-chain semi-crystalline aliphatic polyamide of layer (2) is a short-chain polyamide having a Tm 200 C.

5. The multilayer tubular structure (MLT) according to claim 1, wherein the short-chain semi-crystalline aliphatic polyamide of layer (2) has a crystallization enthalpy 25 J/g, measured according to ISO standard 11357-3:2013.

6. The multilayer tubular structure (MLT) according to claim 1, wherein the short-chain semi-crystalline aliphatic polyamide of layer (2) is selected from the group consisting of PA610, PA 66, PA 6, PA 46, PA 510, PA 410, PA 612, PA 66/6 and PA 6/12 with less than 20% of co-monomer 6 and 12 respectively.

7. The multilayer tubular structure (MLT) according to claim 1, wherein the composition of said layer (2) comprises at least one PA6, PA66 or one PA6/66 or a mixture thereof and at least one PA 6Y, Y being an aliphatic dicarboxylic acid comprising from 9 to 14 carbon atoms, the mean of the average number of carbon atoms per nitrogen atom being from 4 to 9.5.

8. The multilayer tubular structure (MLT) according to claim 1, wherein layer(s) (2) has/have a thickness greater than or equal to 2 times the thickness of layer(s) (1).

9. The multilayer tubular structure (MLT) according to claim 1, wherein the proportion of impact modifier b) of layer (1) is greater than or equal to 1.5 times the proportion of impact modifier b) of layer (2).

10. The multilayer tubular structure (MLT) according to claim 9, wherein the proportion of impact modifier b) of layer (2) is less than 12% by weight.

11. The multilayer tubular structure (MLT) according to claim 1, wherein the proportion of Z.sub.1 is equal to 0.

12. The multilayer tubular structure (MLT) according to claim 1, wherein said structure comprises from the exterior to the interior at least one layer (1) and at least one layer (2).

13. The multilayer tubular structure (MLT) according to claim 12, wherein a layer of binder is present between layer (1) and layer (2).

14. The multilayer tubular structure (MLT) according to claim 12, wherein layer (1) and layer (2) are directly in contact with each other.

15. The multilayer tubular structure (MLT) according to claim 1, wherein a layer (1) is present below layer (2), layer (1) being as defined for layer (1).

16. The multilayer tubular structure (MLT) according to claim 15, wherein layer (1) and layer (1) are identical.

17. The multilayer tubular structure (MLT) according to claim 1, wherein said composition of said layer (2) further comprises at least one aliphatic polyamide selected from among: one polyamide denoted A and an average number of carbon atoms per nitrogen atom denoted C.sub.A ranging from 4 to 9.5, one polyamide denoted B and an average number of carbon atoms per nitrogen atom denoted C.sub.B of between 7 to 10, one polyamide denoted C having an average number of carbon atoms per nitrogen atom denoted C.sub.C of between 9 to 18; on condition that when said interior layer (2) comprises at least three polyamides, at least one of said polyamides B or C is excluded.

18. The multilayer tubular structure (MLT) according to claim 17, wherein the short-chain semi-crystalline aliphatic polyamide of layer (2) is in proportion by weight greater than 70%, relative to the sum of the polyamides present in the composition of layer (2).

19. The multilayer tubular structure (MLT) according to claim 1, wherein said composition of said layer (2) mainly comprises: at least said short-chain semi-crystalline aliphatic polyamide denoted (A) constituted by at least 70% of aliphatic units having an average number of carbon atoms per nitrogen atom denoted C.sub.A ranging from 4 to 8.5, and the remainder to 100% of aliphatic units constituted of at least one unit denoted B having an average number of carbon atoms per nitrogen atom denoted C.sub.B ranging from 7 to 10, and of at least one unit denoted C having an average number of carbon atoms per nitrogen atom denoted C.sub.C ranging from 9 to 18; the average number of carbon atoms per nitrogen atom in units A, B and C further satisfying the following strict inequation: C.sub.A<C.sub.B<C.sub.C, and the mean of the average number of carbon atoms per nitrogen atom in units A, B and C being 4 to 8.5, the enthalpy of fusion of the short-chain polyamide or the mass-weighted average of the enthalpies of fusion of the mixture of short-chain semi-crystalline aliphatic polyamides within said composition being greater than 25 J/g (DSC), the melting temperature of the polyamide or of each of the polyamides being greater than or equal to 200 C.

20. The multilayer tubular structure (MLT) according to claim 1, wherein said composition of said layer (2) mainly comprises: at least said short-chain semi-crystalline aliphatic polyamide denoted (A) constituted by at least 70% of aliphatic units having an average number of carbon atoms per nitrogen atom denoted C.sub.A ranging from 4 to 8.5, and the remainder to 100% of aliphatic units constituted of at least one unit denoted B having an average number of carbon atoms per nitrogen atom denoted C.sub.B ranging from 7 to 10, and at least said short-chain semi-crystalline aliphatic polyamide denoted (A) constituted by at least 70% of aliphatic units having an average number of carbon atoms per nitrogen atom denoted C.sub.A ranging from 4 to 8.5, and the remainder to 100% of aliphatic units constituted of at least one unit denoted C having an average number of carbon atoms per nitrogen atom denoted C.sub.C ranging from 9 to 18, the average number of carbon atoms per nitrogen atom in units A, B and C further satisfying the following strict inequation: C.sub.A<C.sub.B<C.sub.C, and the mean of the average number of carbon atoms per nitrogen atom in units A, B and C being 4 to 8.5, the enthalpy of fusion of the short-chain polyamide or the mass-weighted average of the enthalpies of fusion of the mixture of short-chain semi-crystalline aliphatic polyamides within said composition being greater than 25 J/g (DSC), the melting temperature of the polyamide or of each of the polyamides being greater than or equal to 200 C.

21. The multi-layer tubular structure (MLT) according to claim 19, wherein said aliphatic unit represents from 80% to 97% by weight relative to the sum of the units present in the polyamides of the composition of layer (2).

22. The multilayer tubular structure (MLT) according to claim 1, further comprising an EVOH barrier layer.

23. The multilayer tubular structure (MLT) according to claim 22, wherein said structure comprises from the exterior to the interior:
layer (1)//layer (2)// EVOH//layer (2)//layer (1) (V), layer (1) being as defined for layer (1), layer (2) being as defined for layer (2).

24. The multilayer tubular structure (MLT) according to claim 23, wherein layer (1) and layer (1) are identical and layer (2) and layer (2) are identical.

25. The multilayer tubular structure (MLT) according to claim 1, wherein a semi-aromatic polyamide (PPA) barrier layer is present.

26. The multilayer tubular structure (MLT) according to claim 25, wherein the semi-aromatic polyamide is selected from a polyamide MXD6, PXD6, MXD10, PXD10, or a copolyamide X.sub.2T/X.sub.2Ar, X.sub.2 and X.sub.2 each representing, independently of each other, a linear or branched C.sub.6-C.sub.13 aliphatic diamine, notably PA 9T, PA 9T/9T, PA10T/6T, PA6T/6I, PA6T/66.

27. The multilayer tubular structure (MLT) according to claim 25, wherein said structure comprises from the exterior to the interior: layer (1)//layer (2)//PPA// layer (2)//layer (1), layer (1) being as defined for layer (1), layer (2) being as defined for layer (2).

Description

EXAMPLES

(1) Compositions of the Invention Used to Manufacture the Tubes:

(2) HT=coPA 11/10T 0.7/1.1 molar (Tm 260 C., MFI 300-5=2)+30% EPR1+0.4% stab CuI/KI at .

(3) HTX=coPA 11/10T 0.7/1.1 molar (Tm 260 C., MFI 300-5=2)+18% EPR1+0.4% stab CuI/KI at +5% PA6 (MFI 235-5=6) +5% PA12 (MFI 235-5=6).

(4) HT3=coPA 11/10.T 0.7/1.1 molar (Tm 260 C., MFI 300-5=2)+36% EPR1+0.4% stab CuI/KI at +10% BBSA plasticiser.

(5) P11=PA11 (MFI 235-5=8) +6% EPR1+6% BBSA plasticiser+0.4% stab CuI/KI at .

(6) P610-A=PA610 (MFI 235-5=4)+10% BBSA plasticiser+6% EPR1+0.4% stab CuI/KI at +5% PA6 (MFI 235-5=6)+5% PA12 (MFI 235-5=6).

(7) PA610-B=PA610 (MFI 235-5=4)+12% BBSA plasticiser+6% EPR1+0.4% stab CuI/KI at .

(8) P66-A=PA66 (MFI 275-5=11)+10% BBSA plasticiser+6% EPR1+0.4% stab CuI/KI at +5% PA610 (MFI 235-5=4)+5% PA12 (MFI 235-5=6).

(9) P66-B=PA66 (MFI 275-5=11)+12% BBSA plasticiser+6% EPR1+0.4% stab CuI/KI at .

(10) Binder (Tie)=PA610 (MFI 235-5=4)+10% BBSA plasticiser+6% EPR1+30% PA6 (MFI 235-5=6) +0.4% stab CuI/KI at

(11) With:

(12) EPR1 designating a copolymer of ethylene and propylene with elastomeric nature functionalized by a reactive group with anhydride function (at 0.5-1% by mass), with MFI 9 (at 230 C., below) 10 kg, of Exxellor VA1801 type from the company Exxon used as impact modifier. Its flexural modulus is about 10 MPa according to ISO standard 178:2010 (same conditions as above).

(13) The MFI (Melt Flow Index or index of warm fluidity) is measured according to ASTM D1238.

(14) Stab Cu designating a mixture of mineral stabilizers based on copper and potassium iodide such as

(15) Iodide P201 (BASF company), CuI and KI are in a proportion of 1 to 8.

(16) BBSA butylbenzenesulfonamide plasticiser.

(17) Tm meaning melting temperature (second heating of a DSC according to ISO standard 11357-3:2013).

(18) These compositions are manufactured by conventional compounding in a co-rotating twin screw extruder of Coperion 40 type, at 300 tr/min, at 270 C. or at 300 C. when the ingredients have a melting point higher than 260 C.).

(19) Multi-Layer Tubes of the Invention: The multi-layer tubes are manufactured by co-extrusion. The MLT tubes are manufactured on a conventional multi-layer tube extrusion line as described in EP2098580 or on a conventional Maillefer 60 single-layer line when they are single-layer. The multi-layer tubes manufactured by extrusion above were then assessed according to several criteria: flexibility; VW impact 40 C.; bursting in cold and heat 150 C.; air/air thermal aging (150 C.); Tm is the criterion chosen to characterize the suitability for being used at peak temperatures (up to about 20 C. below the Tm).

(20) The measurement results and methods are indicated in Table I.

(21) TABLE-US-00001 TABLE I structure Flexibility Impact 40 C. Bursting. 23 C. Bursting. 150 C. (1) (2) (3) (4) (4) Examples of the invention ex. 1 HT//P610-A//HT 635 3% 28 8.1 ex. 2 HT//P66-A//HT 640 3% 26.5 9.5 ex. 3 HTX//P66-B//HTX 670 10% 28.5 10.8 ex. 4 HT (300)//P66-A 650 25% 26.7 9.4 ex. 5 HT//P610-B//HT 655 7% 29.2 9.4 Counter-examples cx. 1 P610-A 460 20% 28.5 9.8 cx. 2 P66-A 475 100% 28 nd cx. 3 P66-B 500 100% 29.5 nd cx. 4 HT 1110 10% 29 5.0 cx. 5 HT3 555 10% 17 3.3 cx. 6 HTX 1275 0% 40 6.2 cx. t1 P11//P610-A//P11 440 0% 27.5 8.3 cx. t2 HTX//P11//HTX nd 0% 32 6.9 nd: not determined (1) Single-layer 8*1 mm and multi-layer 8*1 mm tube, the layers of the tri-layers are distributed as follows: 0.15 mm//0.70 mm//0.15 mm (2) Flexural modulus according to ISO 178: 2010 determined at 23 C. with relative humidity: RH50%, expressed in MPa. (3) Impact at 40 C. according to standard VW TL-52435 6.5, PV 3905, in breakage %. (4) Burst at 23 C. and 150 C. according to DIN 53758, in MPa. (5) Resistance to aging at 150 C. in air, half-life in h (corresponds to the doubt in which a breakage rate of 50% is obtained, using as criterion the DIN53758 impact at 40 C. Aging in air is sufficiently representative of aging in air (exterior of the tube)/fluid (interior of the tube) (6) Melting temperature (according to DSC ISO standard 11357-3: 2013) in C. of the composition of the layer (single-layer) or of the composition of each layer (MLT). In the case of MLT tubes, the lowest among them prohibits use beyond this temperature.