SINGLE-LAYER STRUCTURE BASED ON RECYCLED POLYAMIDE

Abstract

A single-layer tubular structure intended to convey fluids for a motor vehicle, formed by a layer formed by a composition predominantly including at least one catalyzed semi-crystalline aliphatic polyamide, the composition being formed by at least 30% by weight, in particular at least 50% by weight, of recycled material originating from at least one single-layer and/or multi-layer tube that was intended to convey fluids for a motor vehicle, the at least one single-layer and/or multi-layer tube being formed by a composition that predominantly includes at least one catalyzed or non-catalyzed polyamide, said at least one single-layer and/or multi-layer tube having been crushed, then at least recompounding with or without the addition of at least one catalyst to be able to be recycled, a simple one-off crushing being excluded.

Claims

1. A single-layer tubular structure intended to convey fluids for a motor vehicle, formed by a layer formed by a composition comprising at least one catalyzed semi-crystalline aliphatic polyamide, said composition being formed by at least 30% by weight of recycled material originating from at least one single-layer and/or multi-layer tube that was intended to convey fluids for a motor vehicle, said at least one single-layer and/or multi-layer tube being formed by a composition that predominantly comprises at least one catalyzed or non-catalyzed polyamide, said at least one single-layer and/or multi-layer tube having been crushed and then at least recompounded with or without the addition of at least one catalyst in order to be able to be recycled, a simple one-off crushing being excluded.

2. The single-layer tubular structure according to claim 1, wherein said composition is formed by at least 50% of recycled material originating from a single-layer and/or multi-layer tube that was intended to convey fluids for a motor vehicle.

3. The single-layer tubular structure according to claim 1, wherein said at least one single-layer and/or multi-layer tube is formed by a composition that predominantly comprises at least one catalyzed polyamide, said at least one single-layer and/or multi-layer tube having been crushed and then at least recompounded without the addition of a catalyst in order to be able to be recycled.

4. The single-layer tubular structure according to claim 1, wherein said at least one single-layer and/or multi-layer tube is formed by a composition that predominantly comprises at least one catalyzed polyamide, said at least one single-layer and/or multi-layer tube having been crushed and then at least recompounded with the addition of a catalyst in order to be able to be recycled.

5. The single-layer tubular structure according to claim 1, wherein said composition of the layer 44-lacks plasticizer and/or impact modifier.

6. The single-layer tubular structure according to claim 1, wherein said composition of the layer comprises at least one compound selected from plasticizer, an impact modifier and an additive.

7. The single-layer tubular structure according to claim 1, wherein the fluid conveyed by said at least one single-layer and/or multi-layer tube is the same as that of said single-layer tubular structure.

8. The single-layer tubular structure according to claim 1, wherein the fluid conveyed by said single-layer and/or multi-layer tube is different from that of said single-layer tubular structure.

9. The single-layer tubular structure according to claim 1, wherein said at least one tube is a single-layer tube.

10. The single-layer tubular structure according to claim 1, wherein said at least one tube is a multi-layer tube

11. The single-layer tubular structure according to claim 1, wherein the Tm of the predominant semi-crystalline aliphatic polyamide of the layer is ≤225° C. as determined by DSC according to ISO standard 11357-3:2013, at a heating rate of 20K/min.

12. The single-layer tubular structure according to claim 1, wherein the predominant semi-crystalline aliphatic polyamide of the layer has a crystallization enthalpy ≥25 J/g, as determined by DSC according to ISO standard 11357-3:2013, at a heating rate of 20K/min.

13. A method for manufacturing a single-layer tubular structure as defined in claim 1, comprising a step of crushing and at least one step of recompounding at least one single-layer and/or multi-layer tube that was intended to convey fluids for a motor vehicle defined in claim 1.

14. The method according to claim 13, wherein at least one recompounding step is carried out with the addition of a catalyst.

15. The method according to claim 14, wherein said at least one single-layer and/or multi-layer tube is non-catalyzed.

16. The method according to claim 14, wherein said at least one single-layer and/or multi-layer tube is a mixture formed by more than 50% of non-catalyzed tube and less than 50% of catalyzed tube.

17. The method according to claim 13, wherein said recompounding step(s) is/are carried out without the addition of a catalyst.

18. The method according to claim 17, wherein said at least one single-layer and/or multi-layer tube is catalyzed.

19. The method according to claim 13, wherein at least one recompounding step is carried out under strong degassing.

20. The method according to claim 13, wherein a step of extruding the crushed and recompounded tube is carried out in order to obtain the tubular structure.

21. A method comprising using at least one single-layer and/or multi-layer tube that was intended to convey fluids for a motor vehicle as defined in claim 1, for the preparation of a single-layer tubular structure intended to convey fluids for a motor vehicle.

Description

EXAMPLES

[0264] The following resins were used in the various compositions of the invention:

[0265] Catalyzed PA11: Polyamide 11 of Mn (number-average molecular mass) 29000. The melting temperature is 190° C.; its melting enthalpy is 56 kJ/m2. The composition of this PA11 comprises 0.25% (+/−0.05%) of H3PO4.

[0266] Non-catalyzed PA12: Polyamide 12 of Mn (number-average molecular mass) 35000. The melting temperature is 178° C.; its melting enthalpy is 54 kJ/m2

[0267] The melting temperature and the melting enthalpy were determined according to ISO standard 11357-3:2013.

[0268] The following additives, plasticizers and impact modifiers were used in the compositions of the invention: [0269] stabilizer: stabilizer consisting of 80% of phenol Lowinox 44625 from Great Lakes, 20% of phosphite Irgafos 168 from Ciba [0270] BBSA: BBSA (butyl benzene sulfonamide) plasticizer, [0271] Imod=generically refers to a polyolefin type impact modifier or the like, such as among others PEBAs (polyether block amide), core-shells, silicons . . . [0272] Imod1: refers to an EPR functionalized by a reactive group with anhydride function (at 0.5-1% by mass), of MFI 9 (at 230° C., below) 10 kg, of Exxellor VA1801 type from Exxon.

[0273] The following compositions were used to produce the tubes according to the invention:

[0274] In the entire description, all the percentages are given in weight.

[0275] In the case of the compositions named “recy”, and “recy2” used for the layer (1) of the tubes of the invention or counterexample tubes, protocols to simulate an aged tube have been used:

The inherent viscosity according to ISO 307:2007 in m-cresol at 20° C. was determined initially on the tubes before use

[0276] The tube is aged according to a standard general protocol that is easily reproducible, which consists in immersing said single-layer tubular structure in FAM-B alcohol-based gasoline and in heating the assembly to 60° C. for 500 h, 1000 h, 1500 h, 2000 h and 5000 hours, then in recovering the tube and analyzing it.

[0277] This standard aging is representative of what the gasoline conveying tubes undergo in 10 years of service in a vehicle in a hot engine.

[0278] The FAM-B alcohol-based gasoline is disclosed in standard DIN 51604-1:1982, DIN 51604-2:1984 and DIN 51604-3:1984.

[0279] In short, FAM-A alcohol-based gasoline is first prepared with a mixture of 50% toluene, 30% isooctane, 15% di-isobutylene and 5% ethanol then FAM-B is prepared by mixing 84.5% FAM A with 15% methanol and 0.5% water.

[0280] In total, FAM-B consists of 42.3% toluene, 25.4% isooctane, 12.7% di-isobutylene, 4.2% ethanol, 15% methanol and 0.5% water.

[0281] After each aging, the inherent viscosity of the tube is determined then the tube is crushed and treated according to two protocols:

[0282] Protocol A: After aging, the crushed tube is recompounded on a Coperion/Werner 40-mm twin-screw extruder with a setpoint of 70 kg/h, 300 rpm, 270° C., with or without the addition of catalyst.

[0283] The inherent viscosity of the tube is then determined.

[0284] Protocol B: After aging, the crushed tube is recompounded on a Coperion/Werner 40-mm twin-screw extruder, with a set-point of 70 kg/h, 300 rpm, 270° C., with or without the addition of catalyst and with a strong degassing of −660 mmHg.

[0285] The inherent viscosity of the tube is then determined.

[0286] The various compositions used for the preparation of the tubes of the invention are as follows: [0287] PA11PL cat=catalyzed PA11+7% BBSA+1% stabilizer [0288] PA12PL=non-catalyzed PA12+12% BBSA+1% stabilizer [0289] PA12PL cat=catalyzed PA12+12% BBSA+1% stabilizer [0290] PA11PL cat-recy=PA11PL cat tube aged according to general protocol, recrushed only. [0291] PA11PL-recy2=PA11PL cat tube aged according to general protocol, recrushed, recompounded according to protocol A, without the addition of catalyst during this recompounding. [0292] PA12PL-recy2=PA12PL tube aged according to general protocol, recrushed, recompounded according to protocol A, without the addition of catalyst during this recompounding. [0293] PA12PL-recy2bis=PA12PL tube aged according to general protocol, recrushed, recompounded according to protocol A, with the addition of catalyst during this recompounding.

[0294] These compositions are manufactured by conventional compounding in a co-rotating twin screw extruder of Coperion 40 type, at 300 rpm, at 270° C. (or at 300° C. when the ingredients have a melting point higher than 260° C.).

[0295] Single-Layer Tubes of the Invention:

the tubes have a dimension of 8*1 mm

[0296] Preparation of Single-Layer Structures (Tubes):

[0297] The single-layer structures are produced by extrusion. An industrial Maillefer multilayer extrusion line is used, equipped with 5 extruders, connected to a multilayer extrusion head with spiral mandrels.

[0298] The screws used are extrusion monoscrews having screw profiles adapted to polyamides. In addition to the 5 extruders and the extrusion head, the extrusion line comprises: [0299] a die-punch assembly, located at the end of the extrusion head; the interior diameter of the die and the exterior diameter of the punch are selected according to the structure to be produced and the materials of which it is composed, as well as the dimensions of the tube and the line speed; [0300] a vacuum tank with an adjustable vacuum level. In this tank water circulates generally maintained at 20° C., in which a gauge is submerged making it possible to shape the tube to its final dimensions. The diameter of the gauge is adapted to the dimensions of the tube to be produced, typically from 8.5 to 10 mm for a tube with an external diameter of 8 mm and a thickness of 1 mm; [0301] a succession of cooling tanks in which water is maintained at around 20° C., allowing the tube to be cooled along the path from the head to the drawing bench; [0302] a diameter meter; [0303] a drawing bench.

[0304] The configuration with 5 extruders is used to produce the tubes ranging from 2 layers to 5 layers, as well as for single-layer tubes.

[0305] Before the tests, in order to ensure the best properties for the tube and good extrusion quality, it is verified that the extruded materials have a residual moisture content before extrusion of less than 0.08%. Otherwise, an additional step of drying the material before the tests, generally in a vacuum dryer, is carried out overnight at 80° C.

[0306] The tubes, which satisfy the features described in the present patent application, were removed, after stabilization of the extrusion parameters, the dimensions of the tubes in question no longer changing over time. The diameter is controlled by a laser diameter meter installed at the end of the line.

[0307] The line speed is typically 20 m/min. It generally ranges from 5 to 100 m/min.

[0308] The screw speed of the extruders depends on the thickness of the layer and on the diameter of the screw as is known to those skilled in the art.

[0309] In general, the temperatures of the extruders and of the tools (head and connector) must be adjusted so as to be sufficiently higher than the melting temperature of the compositions in question, so that they remain in the molten state, thus preventing them from solidifying and jamming the machine.

[0310] The single-layer tubes manufactured by extrusion hereinbefore were then assessed according to several criteria:

[0311] The results are given in Table 1.

TABLE-US-00001 TABLE 1 Inherent viscosity in dl/g after Inherent viscosity in dl/g at t (h) recycling Example Structure 0 500 1000 1500 2000 5000 — Ex1 Single-layer PA11PL cat 1.4 1.5 1.7 1.75 1.6 1.2 — Ex2 Single-layer PA11PL-recy 1.4 1.5 1.7 1.75 1.6 1.2 1.2 Ex3 Single-layer PA11PL-recy2 1.4 1.5 1.7 1.75 1.6 1.2 1.4 Ex4 Monolayer PA12PL 1.48 1.48 1.48 1.4 1.3 1.1 — Ex5 Single-layer PA12PL-recy2  1.15 Ex6 Single-layer PA12PL-recy2bis  1.45 Ex7 Single-layer PA12PL-cat 1.45 1.53 1.75 1.8 1.6 1.15 Ex8 Single-layer PA12PL-cat-recy2 1.4

[0312] The inherent viscosity was determined according to ISO 307:2007 in m-cresol at 20° C. over 10 tubes for each example.

[0313] Table 1 shows that the crushing followed by recompounding without the addition of catalyst fora catalyzed and aged polyamide (PA11PI-cat and PA12-PL-cat) makes it possible to regain the original inherent viscosity and thus the qualities of the original tube while a simple crushing does not make it possible to regain the original inherent viscosity.

[0314] It also shows that crushing followed by recompounding without the addition of catalyst for a non-catalyzed and aged polyamide (PA11PI-cat) does not make it possible to regain the original inherent viscosity and thus the qualities of the original tube.