BLOW MOLDING COMPOSITIONS BASED ON BRANCHED POLYAMIDES AND USES THEREOF

Abstract

The present invention relates to a composition for blow-molding or extrusion, in particular blow-molding, comprising by weight: a) from 88 to 99.95%, more particularly from 89 to 99.9%, in particular from 93 to 99.9%, of at least one semicrystalline aliphatic polyamide having a carbon number per nitrogen atom of greater than or equal to 7, more particularly greater than or equal to 8, b) from 0.05% to 10%, more particularly from 0.1% to 9%, in particular from 0.1% to 5% by weight of at least one branching agent chosen from polyepoxides, polyanhydrides, more particularly polymaleic anhydrides and polyepoxides, c) from 0 to 2% of at least one additive, more particularly from 0.1 to 2%, the composition having, after compounding, a melt viscosity of from 10 000 to 300 000 Pa.Math.s, preferably from 15 000 to 220 000 Pa.Math.s, as measured in plane-plane geometry according to standard 6721-10:2015 at a temperature of 250? C., a frequency of 0.292 rad/s and a deformation of 2%, the sum of the constituents a)+b)+c) making 100% by weight.

Claims

1. A composition for blow-molding or extrusion comprising by weight: a) from 88 to 99.95% of at least one semicrystalline aliphatic polyamide having a carbon number per nitrogen atom of greater than or equal to 7, b) from 0.05% to 10% by weight of at least one branching agent chosen from polyepoxides, polyanhydrides and polyisocyanates, c) from 0 to 2% of at least one additive, the composition having, after compounding, a melt viscosity of from 10,000 to 300,000 Pa.Math.s, as measured in plane-plane geometry according to ISO standard 6721-10:2015 at a temperature of 250? C., a frequency of 0.292 rad/s and a deformation of 2%, the sum of the constituents a)+b)+c) making 100% by weight.

2. The composition for blow-molding or extrusion as claimed in claim 1, wherein said compounding is carried out at a temperature of the molten polymer of greater than 280? C., with an average residence time of from 20 seconds to 10 minutes.

3. The composition for blow-molding or extrusion as claimed in claim 1, wherein the impact modifiers are excluded from said composition.

4. The composition for blow-molding or extrusion as claimed in claim 1, wherein the ratio of the viscosities as measured in plane-plane geometry in the melt state at 0.292 rad.Math.s.sup.?1/292 rad.Math.s.sup.?1 is from 10 to 200.

5. The composition for blow-molding or extrusion as claimed in one claim 1, wherein said branching agent has an average functionality in terms of epoxy, anhydride or isocyanate functions of from 1.8 to 200.

6. The composition for blow-molding or extrusion as claimed in one claim 1, wherein said branching agent has an average equivalent weight in terms of epoxy, anhydride or isocyanate functions of from 100 to 10,000 g/mol.

7. The composition for blow-molding as claimed in claim 1, wherein the Rheotens force of the composition after compounding is from 22 mN to 200 mN.

8. The composition for blow-molding or extrusion as claimed in claim 1, wherein said semicrystalline aliphatic polyamide is chosen from PA610, PA612, PA 614, PA 10, PA11 and PA12.

9. A monolayer or multilayer tubular structure configured for the transport, distribution or storage of gasoline, comprising at least one sealing layer comprising a composition as defined in claim 1.

10. The monolayer or multilayer tubular structure as claimed in claim 9, wherein said sealing layer, on first storage of gasoline, has at most 1 g/m2 of insoluble extract and also at most 15 g/m2 of soluble extract being removed by washing of the single-layer or multilayer tubular structure as an overall system, determined for a 20?4?4 cm3 tank having a wall thickness of 2 mm.

11. The monolayer or multilayer tubular structure as claimed in claim 9, wherein said structure is a monolayer structure.

12. The monolayer or multilayer tubular structure as claimed in claim 9, wherein said structure is a multilayer structure and comprises a barrier layer.

13. The monolayer or multilayer tubular structure as claimed in claim 12, wherein said barrier layer is made of EVOH.

14. A method of using 0.05% to 10% by weight of at least one branching agent chosen from polyepoxides, polyanhydrides, with 88% to 99.95% of at least one semicrystalline aliphatic polyamide having a carbon number per nitrogen atom of greater than or equal to 7, and optionally an additive for the constitution of a composition for blow-molding, as defined in claim 1, the melt viscosity of which after compounding is from 10,000 to 300,000 Pa.Math.s, as measured in plane-plane geometry at a temperature of 250? C., a frequency of 0.292 rad/s and a deformation of 2%.

15. A process for preparing a composition for blow-molding or extrusion as defined in claim 1, comprising a step of compounding said composition.

16. A process for preparing a monolayer or multilayer tubular structure as defined in claim 9, comprising a step of blow-molding or extrusion of the composition.

17. A process for preparing a monolayer or multilayer tubular structure as claimed in claim 16, comprising a preliminary step of compounding the composition.

Description

EXAMPLES

[0321] The comparative (CE1 to CE4) and inventive (C11 to C16) compositions of Table 2 below were prepared by compounding under the following conditions:

[0322] The alloys were manufactured using a ZSK 40 mm twin-screw extruder (Coperion). The temperature of the barrels was set to 280? C. and the screw speed was 300 rpm with a throughput of 60 kg/h.

[0323] The PA6 used is a polyamide 6 having an acid chain end concentration of 25 ?eq/g and an amine chain end concentration of 22 ?eq/g.

[0324] The PA610 used is a polyamide 610 having an acid chain end concentration of 27 ?eq/g and an amine chain end concentration of 19 ?eq/g.

[0325] The PA612 used is a polyamide 612 having an acid chain end concentration of 22 ?eq/g and an amine chain end concentration of 20 ?eq/g.

[0326] The PA11 used is a phosphoric acid-catalyzed polyamide 11 having an acid chain end concentration of 30 ?eq/g and an amine chain end concentration of 33 ?eq/g.

[0327] Joncryl ADR 4400 is from BASF.

[0328] Xibond 125 is from Polyscope.

[0329] Lotader 3410 is from SK functional polymer.

[0330] The stabilizer Anox NBD TL 89 is from SI group.

[0331] The melt viscosity was measured using an Ares G2 rotational rheometer equipped with a 25 mm plane-plane geometry at a temperature of 250? C., at 0.292 rad/s (residence time before launch 5 min under nitrogen, deformation of 2%, sweep of 628 rad/s at 0.062 rad/s and 3 points per decade, taking of a point on 3 cycles, gap of 1.5 mm).

[0332] The Rheotens force is determined using a Rheotens 71.97 instrument from Gottfert. A Rheotens instrument is a device equipped with notched wheels capable of pulling on a ring at the outlet of a Rheotester 2000 capillary rheometer from Gottfert, shear at the capillary 100 s.sup.?1, die of L/D=30 and D=1 mm, temperature 250? C., distance between the outlet of the ring and the axle of the notched wheels 105 mm, acceleration of the wheels 2.4 mm/s.sup.?2. The water uptake is determined either in an oven under a controlled atmosphere at 100% RH or in water, in all cases after saturation at 70? C., and the measurement of this water uptake is made by weighing the sample at 23? C., for regular sampling times, spaced several days apart, until an equilibrium state is observed, which is reached when the mass of the sample becomes constant (to within the measurement uncertainty) for three consecutive sampling times. In the case of conditioning in water, the equilibrium reached corresponds to the water saturation of the polymer, at a temperature of 70? C.

[0333] The resistance to ZnCl2/CaCl2 stress cracking was determined according to the protocol below:

[0334] Test specimens 1A having a thickness of 4 mm were clamped onto a mandrel with a radius of 32.5 mm and were then immersed for 300 h at 23? C. in a 50% ZnCl2 solution. The test specimen is then dried at 23? C. for 72 h. The specimens are subsequently analyzed by observation for the presence of stress cracking, and a stress cracking resistance score was awarded to each sample. 0: very low resistance, sample greatly cracked. 5: very good resistance, sample intact.

[0335] The CE1C permeability measurement involves measuring 30 ml of CE10 into a dish and then covering it with the 3 mm plate under evaluation. The assembly is placed in a temperature-controlled chamber. It is weighed periodically to determine the amount of solvent vapor which diffuses through the plate.

[0336] The flow, normalized with the surface area of the sample, is obtained by virtue of the slope of the curve for the change in weight (solvent) as a function of time.

[0337] The compositions of the invention and the comparative compositions were tested on several parameters.

[0338] The MFI, abbreviation for melt flow index, was measured according to ISO standard 1133:2011.

[0339] The results are detailed in Table 1.

TABLE-US-00001 TABLE 1 CE 1 CE 2 CE 3 CE 4 CI 1 CI 2 CI 3 CI 4 CI 5 CI 6 PA 6 76 PA 612 91 PA 610 91 PA 11 99 84 84 98 98.5 94 91 JONCRYL ADR 0.5 4400 Xibond 125 15 1 Lotader 3410 23 15 4 8 8 8 Anox NBD TL 89 1 1 1 1 1 1 1 1 1 1 total 100 100 100 100 100 100 100 100 100 100 viscosity at 0.292 9840 5819 7127 87302 191179 143026 23645 31047 30 267 28940 rad/s Stream of CE 10 9 17 16 25 16 17 18 20 17 15 at 60? C. on 100*100*3 mm injected plates (g. 3 mm/m2. 24 h) Resistance to 0 5 5 5 5 5 5 5 3.5 3 ZnCl2/CaCl2 stress cracking, 0-5 (0 = poor, 5 = very good resistance) MFI 0 6 6 0 0 0 0 0 0 0

[0340] The results show that the use of a branching agent in a particular range and of a polyamide with an average number of carbon atoms per nitrogen atom of greater than or equal to 7 makes it possible to obtain compositions exhibiting the best compromise on the various characteristics such as the viscosity at 250? C., permeability to gasolines and resistance to zinc chloride.

[0341] All the compositions according to the invention have an MFI equal to 0, which means that nothing flows into the machine.