POLYAMIDE-BASED COMPOSITION FOR PIPES CONTAINING OIL OR GAS

Abstract

The invention relates to the use of a composition comprising at least one polyamide, of which at least one is a semicrystalline copolyamide comprising at least one minor motif resulting from the polycondensation of: at least one diamine with at least one polymerised fatty acid, in particular a fatty acid dimer; or at least one diamine dimer with at least one carboxylic acid; or at least one amino acid dimer; or mixtures of same, as a sealing coating in a pipe containing oil or gas, said pipe being used in the operation of offshore oil or gas deposits.

Claims

1. A leaktight layer in a pipe containing oil or gas, the pipe being configured for use in the exploitation of undersea (offshore) oil or gas deposits, the leaktight layer comprising a composition comprising at least one polyamide, of which at least one of said polyamide is a semicrystalline copolyamide comprising at least one minor unit derived from the polycondensation: of at least one diamine with at least one polymerized fatty acid, or of at least one diamine dimer with at least one dicarboxylic acid, or of at least one amino acid dimer, in particular derived from the polycondensation: of at least one diamine with at least one polymerized fatty acid, or of at least one diamine dimer with at least one dicarboxylic acid, or mixtures thereof.

2. The leaktight layer as claimed in claim 1, in which said minor unit comprises at least one of the following formulae: either the residues of a fatty acid dimer of formula (I) below: ##STR00052## or the residues of a diamine dimer of formula (II) below: ##STR00053## or the residues of an amino acid dimer of formula (III) below: ##STR00054## or a mixture thereof, in which formulae, independently of each other: n is from 1 to 10, p is from 1 to 10, ##STR00055## corresponds to a structure chosen from: ##STR00056## m being from 1 to 5, in which R.sub.1 and R.sub.2 represent, independently of each other, H or a C.sub.1 to C.sub.12, and ##STR00057## in which R.sub.1 and R.sub.2 are cyclized to form a structure: i) with one ring of the type cyclohexane: ##STR00058## or phenyl: ##STR00059## ii) with two rings of the 1,2,3,4-tetrahydronaphthalene type: ##STR00060## or of the bicyclo[4.4.0]decane type: ##STR00061## R.sub.3 and R.sub.4 being, in the one-ring or two-ring structures, C1 to C10 alkyl residues, or a mixture thereof, the total number of carbon atoms in the diacid of formula (I), the diamine of formula (II) and the amino acid of formula (III) being greater than or equal to 30.

3. The leaktight layer as claimed in claim 1, in which the pipe is a hose pipe.

4. The leaktight layer as claimed in claim 1, in which the copolyamide is an aliphatic copolyamide.

5. The leaktight layer as claimed in claim 1, in which the viscosity in solution of the composition, as determined according to the standard ISO 307:2007 in m-cresol at a temperature of 20 C., is greater than 1.

6. The leaktight layer as claimed in claim 1, in which the Tm of the composition is greater than 170 C., as determined according to the standard ISO 11357-3:2013 at a rate of 20 K/min by DSC.

7. The leaktight layer as claimed in claim 1, in which at least one of the other units of said copolyamide is a unit A chosen from a unit obtained from a C.sub.6 to C.sub.12 amino acid, a unit obtained from a C.sub.6 to C.sub.12 lactam, and a unit corresponding to the formula (Ca aliphatic diamine).(Cb aliphatic diacid), with a representing the number of carbon atoms in the diamine and b representing the number of carbon atoms in the diacid, a and b each being between 4 and 22.

8. The leaktight layer as claimed in claim 1, in which the mole proportion of said at least one minor unit in the semicrystalline copolyamide is from 1% to 20% relative to the sum of all the units of said copolyamide.

9. The leaktight layer as claimed in claim 1, in which said minor unit is an X.diacid unit of formula (I), X being an aliphatic diamine.

10. The leaktight layer as claimed in claim 9, in which ##STR00062## corresponds to ##STR00063##

11. The leaktight layer as claimed in claim 9, in which the polymerized fatty acid comprises a fatty acid dimer in a proportion of at least 75% by weight.

12. The leaktight layer as claimed in claim 9, in which the number of carbons in the diamine X is greater than 8.

13. The leaktight layer as claimed in claim 6, in which the unit A is a unit obtained from the polycondensation of a lactam or an amino acid.

14. The leaktight layer as claimed in claim 6, in which the unit A is a unit obtained from the polycondensation of a Ca aliphatic diamine and a Cb aliphatic dicarboxylic acid.

15. The leaktight layer as claimed in claim 14, in which the unit A is chosen from PA614, PA618, PA1010, PA1012, PA1014, PA1018, PA1210, PA1212, PA1214 and PA1218.

16. The leaktight layer as claimed in claim 1, in which the composition comprises a polyamide chosen from an aliphatic, cycloaliphatic or aromatic polyamide, and said at least one semicrystalline polyamide.

17. The leaktight layer as claimed in claim 16, in which said polyamide is an aliphatic or cycloaliphatic polyamide that is identical to the unit A of said semicrystalline polyamide.

18. The leaktight layer as claimed in claim 1, in which the composition also comprises at least one polyolefin.

19. The leaktight layer as claimed in claim 1, in which the composition also comprises at least one plasticizer.

20. The leaktight layer as claimed in claim 1, in which the composition also comprises at least one additive.

21. The leaktight layer as claimed in claim 1, in which the composition comprises, on a weight basis: 70% to 96% of said semicrystalline copolyamide optionally comprising from 0 to 70% by weight of another polyamide, 0 to 25% by weight, advantageously from 0 to 15%, by weight, of a polyolefin comprising an epoxy, anhydride or acid function, introduced by grafting or by copolymerization, and 3% to 20% by weight of a plasticizer, 0 to 10% by weight of an additive.

22. A pipe, in particular a hose pipe, intended to be used in the exploitation of undersea (offshore) oil or gas deposits, comprising at least one leaktight layer obtained from a composition as defined according to claim 1.

23. The pipe as claimed in claim 22, wherein it also comprises at least one second layer, which is not leaktight, formed from one or more metal elements, the second layer being in contact with the oil or gas conveyed, the layer being placed around the second layer so as to ensure the leaktightness.

24. The pipe as claimed in claim 22, wherein it also comprises at least one third layer of metal or a composite material, the third layer being placed around the layer so as to compensate for the internal pressure of the oil or gas conveyed.

25. The hose pipe as claimed in claim 22, wherein it also comprises at least one fourth protective layer placed around the layer or, where appropriate, the third layer.

26. A composition comprising, on a weight basis: 70% to 96% of a semicrystalline copolyamide as defined in claim 1, optionally comprising from 0 to 70% by weight of another polyamide, from 2% to 10% by weight of a polyolefin comprising an epoxy, anhydride or acid function, introduced by grafting or by copolymerization, from 3% to 20% by weight of a plasticizer, and from 0 to 10% by weight of an additive.

27. The composition as claimed in claim 26, in which said other polyamide is an aliphatic polyamide.

28. The composition as claimed in claim 26, in which said minor unit comprises at least one of the following formulae: either the residues of a fatty acid dimer of formula (I) below: ##STR00064## or the residues of a diamine dimer of formula (II) below: ##STR00065## or the residues of an amino acid dimer of formula (III) below: ##STR00066## or a mixture thereof, in which formulae, independently of each other: n is from 1 to 10, p is from 1 to 10, ##STR00067## corresponds to a structure chosen from: ##STR00068## m being from 1 to 5, in which R.sub.1 and R.sub.2 represent, independently of each other, H or a C.sub.1 to C.sub.12, and ##STR00069## in which R.sub.1 and R.sub.2 are cyclized to form a structure: i) with one ring of the type cyclohexane: ##STR00070## or phenyl: ##STR00071## ii) with two rings df the 1,2,3,4-tetrahydronaphthalene type: ##STR00072## or of the bicyclo[4.4.0]decane type: ##STR00073## R.sub.3 and R.sub.4 being, in the one-ring or two-ring structures, C1 to C10 alkyl residues, or a mixture thereof, the total number of carbon atoms in the diacid of formula (I), the diamine of formula (II) and the amino acid of formula (III) being greater than or equal to 30.

29. The composition as claimed in claim 26, in which said minor unit is an X.diacid unit of formula (I), X being an aliphatic diamine.

Description

DESCRIPTION OF THE FIGURES

[0309] FIG. 1 represents the hydrolysis at 140 C. and pH 4 of extruded pieces obtained from various formulated compositions of table III and measured according to ASTM D638 type IV chopped into 6 mm strips.

[0310] The residual elongation is about twice as long for equivalent aging. The service life to reach an elongation at break of 50% (usual criterion) is markedly longer.

[0311] The extruded piece obtained with the formulated composition of the invention with Pripol 1009 thus has a resistance to hydrolysis that is very markedly improved relative to a piece obtained with a formulation based on PA11 or PA11/10T.

[0312] x axis: service life in hours

[0313] y axis: Elongation at break (%)

[0314] FIG. 2 shows the change in inherent viscosity as a function of the aging time measured during the hydrolysis test performed for FIG. 1.

[0315] Measurement of the inherent viscosity is performed in m-cresol according to the method well known to those skilled in the art. The standard ISO 307:2007 is followed, but changing the solvent (use of m-cresol instead of sulfuric acid), the temperature (20 C.) and the concentration (0.5% by mass).

[0316] FIG. 2 shows that the drop in viscosity is not a deciding factor for the mechanical properties of the various formulations, since the viscosities of said formulations all reach a plateau whose value is on the whole neither good nor poor (except for the formulation FC4). However, this criterion is not sufficiently revealing as regards the resistance to hydrolysis, since only the composition of the invention has these resistance properties, whereas the viscosity values at the plateau are substantially identical, with the exception of FC4.

[0317] In other words, it does not suffice to introduce a monomer which renders flexible in order to obtain good mechanical properties of a formulation.

[0318] x axis: aging time in hours

[0319] y axis: Inherent viscosity (dl/g)

[0320] FIG. 3 represents the hydrolysis at 140 C. and pH 4 of extruded pieces obtained from various formulated compositions of table III and measured according to ASTM D638 type IV chopped into 6 mm strips.

[0321] x axis: aging time in hours

[0322] y axis: Elongation at break (%)

[0323] FIG. 4 shows the service life (hydrolysis at pH 4, ASTM D638 type IV) of the composition of the invention (FI1) compared with that of a prior art composition (FC6).

[0324] x axis: 1/T in K

[0325] y axis: Number of hours

[0326] This figure shows that the improvement in the service life temperature at 20 years is +20 C. for the composition of the invention compared with a PA11 of the prior art.

EXAMPLES

[0327] 1. Preparation of a Polymer of the Composition of the Invention

[0328] The following compositions were prepared:

TABLE-US-00001 TABLE I Weighings I1 C1 C3 PA11/10.Pripol C4 Polyamide and PA11/10T C2 11/BHMTA.10 1009 PA11/NHAU Molar composition 19/1 PA11 200/1 19/1 6/1 Unit Terephthalic acid 1.31 kg 11- 30.32 33 32.66 27.62 26.4 kg Aminoundecanoic acid Decanediamine 1.37 1.26 kg Sebacic acid 0.25 kg Pripol 1009 4.12 kg BisHMTA 0.17 kg N-Heptyl-11- 6.6 kg aminoundecanoic acid Deionized water 4 4 4 4 4 kg 85% H.sub.3PO.sub.4 23.3 23.3 23.3 23.3 g

[0329] BisHMTA: Bis(Hexamethylene)Triamine

[0330] The Pripol 1009 used has a hydroxyl number IOH=196 mg KOH/g, which gives an equivalent molar mass equal to 572.6 g/mol.

[0331] The Pripol 1009 is formed from: 98.5% of dimer, 1% of trimer, 1% of 1.5-mer and 0.1% of monomer.

NHAU: N-Heptyl-11-Aminoundecanoic Acid

[0332] The synthetic conditions were as follows:

[0333] After loading, the 100-liter autoclave reactor is deoxygenated by sequences of placing under nitrogen pressure followed by pressure release. The reactor contents are heated to 240 C. under the autogenous pressure and with stirring and then maintained for 1 hour under these conditions. The reactor is then depressurized to a pressure of 0.2 bar relative over 2 hours and then maintained for 30 minutes under these conditions (*). The polymer obtained is then discharged from the reactor in the form of rods and then in the form of granules. (*) In the case of example C4, a step of polymerization at an absolute pressure of 250 mbar for 60 minutes is added.

[0334] In a similar manner to I1, I2 (PA11/10.Pripol 1009 9/1), 13 (PA11/10.Pripol 1009 25/1), 14 (PA11/10.Pripol 1009 30/1) and I5 (PA11/10.Pripol 1013 19/1) were synthesized.

[0335] The Pripol 1013 used has a hydroxyl number IOH=196 mg KOH/g.

[0336] The Pripol 1013 is formed from: 96% of dimer, 2.5% of trimer, 1.5% of 1.5-mer and 0.1% of monomer. The polymers have the following characteristics:

TABLE-US-00002 TABLE II I1 C1 C3 PA11/10.Pripol C4 PA11/10T C2 11/BHMTA.10 1009 PA11/NHAU Composition 19/1 PA11 200/1 19/1 6/1 Acidity (meq/g) 0.056 0.057 0.069 0.056 0.066 Basicity (meq/g) 0.054 0.053 0.05 0.04 0.059 Inherent 1.54 1.53 1.55 1.41 1.41 viscosity m- cresol (dl/g) Tm ( C.) 176 191 190 174 166 Tc ( C.) 124 152 151 145 136 Enthalpy of 45 63 61 48 50 crystallization (J/g) Tg ( C.) 45 44 46 31 11 I2 I3 I4 I5 PA11/ PA11/ PA11/ PA11/ 10.Pripol 10.Pripol 10.Pripol 10.Pripol 1009 1009 1009 1013 Composition 9/1 25/1 30/1 19/1 Acidity 0.049 0.055 0.059 0.059 (meq/g) Basicity 0.051 0.051 0.041 0.038 (meq/g) Inherent 1.37 1.45 1.41 1.42 viscosity m- cresol (dl/g) Tm ( C.) 168 181 181 178 Tc ( C.) 145 136 150 134 Enthalpy of 51 52 58 55 crystallization (J/g) Tg ( C.) 27 33 34 32

[0337] Measurement of the inherent viscosity is performed in m-cresol according to the standard ISO 307:2007, but with the solvent being changed (use of m-cresol instead of sulfuric acid) and the temperature being 20 C.

[0338] The enthalpy of crystallization of said matrix polymer is measured by differential scanning calorimetry (DSC) according to the standard ISO 11357-3:2013. The heating and cooling rate is 20 C./min.

[0339] The Tm and the Tc are measured by differential scanning calorimetry (DSC) according to the standard ISO 11357-3:2013. The heating and cooling rate is 20 C./min.

[0340] The Tg is measured by differential scanning calorimetry (DSC) according to the standard ISO 11357-2:2013. The heating and cooling rate is 20 C./min.

[0341] The Mn of the thermoplastic polymer is determined by titration (assay) of the end functions according to a potentiometric method (direct assay of the acids or bases).

[0342] 2. Preparation of the Formulated Compositions

[0343] The following formulations were prepared (Table III):

TABLE-US-00003 TABLE III Formulation Invention Reference FC1 FI1 FC3 FC2 FC4 FC5 FC6 C1 82.8 I1 82.8 C2 82.8 88.8 87 C3 82.8 C4 98.8 Exxelor VA 1801 10 10 10 10 10 ANOX NDB TL89 1.2 1.2 1.2 1.2 1.2 1.2 BBSA 6 6 6 6 13 Formulation Formulation Formulation Formulation Invention Invention Invention Invention Reference FI2 FI3 FI4 FI5 I2 82.8 I3 82.8 I4 82.8 I5 82.8 Exxelor VA 1801 10 10 10 10 ANOX NDB TL89 1.2 1.2 1.2 1.2 BBSA 6 6 6 6 AnoxNDB TL89: organic stabilizer of phenol phosphite type, sold by Chemtura.