WO2006024715A1

WO2006024715A1 - Fluid transporting tube

Info

Publication number: WO2006024715A1
Application number: PCT/FR2005/001737
Authority: WO
Inventors: Henri-Jean Caupin; Alexander Korzhenko; Stéphane BERGERE
Original assignee: Arkema
Priority date: 2004-08-03
Filing date: 2005-07-06
Publication date: 2006-03-09

Abstract

The invention concerns a fluid transporting tube comprising at least one inner layer (3), one protective outer layer (5), and an intermediate heat-regulating device (10) connected to a voltage source and adapted to heat the transported fluid to an equilibrium or setpoint temperature using a thermistor (12) with positive temperature coefficient whereof the electrical resistance is self-controlled by the temperature and which is connected to the voltage source (V) by at least two conductive elements (14, 15) which supply the current required to heating it. The invention is characterized in that each conductive element (14, 15) is a wire which is supported by a textile web (17) wound about the tube inner layer (3), and in that said inner layer (3) is made: at least of one thermoplastic polymer, and/or, of at least one thermoplastic elastomer selected among the group consisting of thermoplastic polyurethanes, ether/ester copolymers, ether/amide copolymers and ethylene or propylene mixtures with a non-crosslinked ethylene/propylene copolymer.

Description

FLUID TRANSPORT TUBE.

The invention relates to a fluid transport tube which is equipped with a thermal control device so that the transported liquid may be freeze-free and facilitate its flow in the tube.

In general, the variation of the viscosity of a liquid with the temperature is in particular an important disadvantage that arises in the flow of liquids in the fluid transport tubes subjected to temperature variations.

An object of the invention is to overcome this drawback and, to this end, the invention proposes a fluid transport tube comprising at least one inner layer, an outer protective layer, an intermediate thermal regulation device connected to a source. voltage and adapted to heat the transported fluid to an equilibrium or setpoint temperature using a positive temperature coefficient thermistor whose resistance is self-controlled by the temperature and which is connected to the voltage source by at least two conductive elements which provide the current necessary for its heating, and which is characterized in that each conductive element is a wire which is supported by a textile web in the form of a braid wound around the inner layer of the tube, and what said inner layer is based on:

at least one thermoplastic polymer, and / or

at least one thermoplastic elastomer chosen from the group consisting of thermoplastic polyurethanes (TPU), ether / ester copolymers (COPE), ether / amide copolymers (PEBA) and mixtures of ethylene or propylene with a copolymer uncrosslinked ethylene / propylene (EPR).

Advantageously, the inner layer may be based on: at least one thermoplastic polymer of polyamide type

(PA) such as, without limitation, PA 6 and its alloys, PA 6.6, PA 11, PA 12, PAs of type 6.10, 6.12, 10.10 and beyond, PASA (amorphous semi-aromatic polyamides) and their alloys with semi-crystalline PAs, and / or

at least one thermoplastic elastomer of ether / amide copolymer type (PEBA). As polyamides that may be used according to the invention, mention may be made of condensation products:

one or more amino acids, such as aminocaproic, amino-7-heptanoic, amino-11-undecanoic and amino-12-dodecanoic acids of one or more lactams such as caprolactam, oenantholactam and lauryllactam;

one or more salts or mixtures of diamines such as hexamethylenediamine, dodecamethylenediamine, metaxylyenediamine, bis-p-aminocyclohexylmethane and trimethylhexamethylenediamine with diacids such as isophthalic, terephthalic, adipic, azelaic, suberic, sebacic and dodecane.

By way of example of polyamide, mention may be made of PA 6 and PA 6-6.

It is also possible to use copolyamides advantageously. Copolyamides resulting from the condensation of at least two alpha omega aminocarboxylic acids or two lactams or a lactam and an alpha omega aminocarboxylic acid may be mentioned. Mention may also be made of the copolyamides resulting from the condensation of at least one alpha omega aminocarboxylic acid (or a lactam), at least one diamine and at least one dicarboxylic acid. By way of example of lactams, mention may be made of those having from 3 to

12 carbon atoms on the main ring and can be substituted. Examples that may be mentioned include β, β-dimethylpropriolactam, α, α-dimethylpropriolactam, amylolactam, caprolactam, capryllactam and lauryllactam. As an example of alpha omega aminocarboxylic acid, there may be mentioned amino-undecanoic acid and aminododecanoic acid. As examples of dicarboxylic acid that may be mentioned are adipic acid, sebacic acid, isophthalic acid, butanedioic acid, 1,4-cyclohexyldicarboxylic acid, terephthalic acid, sodium or lithium salt. sulphoisophthalic acid, dimerized fatty acids (these dimerized fatty acids have a dimer content of at least 98% and are preferably hydrogenated) and dodecanedioic acid HOOC- (CH 2) 1 OC-OOH.

The diamine may be an aliphatic diamine having 6 to 12 carbon atoms, it may be aryl and / or saturated cyclic. By way of examples, mention may be made of hexamethylenediamine, piperazine, tetramethylenediamine, octamethylene diamine, decamethylene diamine, dodecamethylenediamine, 1,5 diaminohexane and 2,2,4-trimethyl-1,6-trimethylamine. diamino-hexane, diamine polyols, isophorone diamine (IPD), methyl pentamethylenediamine (MPDM), bis (aminocyclohexyl) methane (BACM), bis (3-methyl-4-aminocyclohexyl) methane (BMACM). By way of examples of copolyamides, mention may be made of copolymers of caprolactam and lauryl lactam (PA 6/12), copolymers of caprolactam, adipic acid and hexamethylenediamine (PA 6 / 6-6), copolymers of caprolactam, lauryl lactam, adipic acid and hexamethylenediamine (PA 6/12 / 6-6), copolymers of caprolactam, lauryl lactam, amino undecanoic acid, azelaic acid and hexamethylene diamine (PA 6 / 6-9 / 11/12), copolymers of caprolactam, lauryl lactam, amino undecanoic acid, adipic acid and hexamethylenediamine (PA 6 / 6-6 / 11 / 12), copolymers of lauryl lactam, azelaic acid and hexamethylenediamine (PA 6-9 / 12). Advantageously, the copolyamide is chosen from PA 6 /

12 and PA 6 / 6-6.

Mixtures of polyamides can be used. Advantageously, the relative viscosity of the polyamides, measured in a 1% solution in sulfuric acid at 20 ^° C., is between 1, 5 and 6. It is not beyond the scope of the invention to replace part of the polyamide ( A) by a polyamide block block copolymer polyether, that is to say using a mixture comprising at least one of the foregoing polyamides and at least one polyamide block copolymer and polyether blocks.

The polyamide block and polyether block copolymers result from the copolycondensation of polyamide sequences with reactive ends with polyether sequences with reactive ends, such as, inter alia:

1) Polyamide sequences with diamine chain ends with polyoxyalkylene sequences with dicarboxylic chain ends. 2) Polyamide sequences having dicarboxylic chain ends with polyoxyalkylene sequences having diamine chain ends obtained by cyanoethylation and hydrogenation of aliphatic alpha-omega dihydroxylated polyoxyalkylene sequences known as polyetherdiols. 3) Polyamide sequences with dicarboxylic chain ends with polyetherdiols, the products obtained being, in this particular case, polyetheresteramides. These copolymers are advantageously used.

The polyamide sequences with dicarboxylic chain ends come, for example, from the condensation of alpha-omega-aminocarboxylic acids, lactams or dicarboxylic and diamine diacids in the presence of a dicarboxylic acid chain-limiting agent.

The polyether may be for example a polyethylene glycol (PEG), a polypropylene glycol (PPG) or a polytetraethylene glycol (PTMG). The latter is also called polytetrahydrofuran (PTHF).

The molar mass in number Mn of the polyamide sequences is between 300 and 15,000 and preferably between 600 and 5,000. The mass Mn of the polyether blocks is between 100 and 6,000 and preferably between 200 and 3,000. Polyamide blocks and polyether blocks may also comprise patterns distributed randomly. These The polymers can be prepared by the simultaneous reaction of the polyether and the precursors of the polyamide blocks.

For example, polyetherdiol, a lactam (or an alpha-omega amino acid) and a chain-limiting diacid can be reacted in the presence of a little water. A polymer having essentially polyether blocks, polyamide blocks of very variable length, but also the various reagents reacted randomly are obtained which are distributed statistically along the polymer chain.

These polymers with polyamide blocks and polyether blocks, whether they come from the copolycondensation of previously prepared polyamide and polyether blocks or from a one-step reaction, have, for example, Shore D hardnesses which can be between 20 and 75 and advantageously between 30 and 70 and an inherent viscosity between 0.8 and 2.5 measured in metacresol at 250 ° C for an initial concentration of 0.8 g / 100 ml. The MFI can be between 5 and 50 (235 ° C under a load of 1 kg).

The polyetherdiol blocks are either used as such and copolycondensed with polyamide blocks having carboxylic ends, or they are aminated to be converted into polyether diamines and condensed with polyamide blocks having carboxylic ends. They can also be mixed with polyamide precursors and a chain limiter to make the polyamide block and polyether block polymers having statistically distributed patterns.

Polymers with polyamide blocks and polyethers are described in US Pat. Nos. 4,331,786, 4,155,415, 4,195,155, 4,839,441, 4,884,014, 4,230,838 and 4,332,920.

The ratio of the amount of polyamide block copolymer and polyether block to the amount of polyamide is, by weight, advantageously between 10/90 and 60 / 40. For example, the mixtures of (i) PA 6 and (ii ) PA 6 block copolymer and PTMG blocks and mixtures of (i) PA 6 and (ii) PA 12 block copolymer and PTMG blocks. PA 6, IePA 6-6 and PA 6 / 6-6 are advantageously used. Other polyamides that may be used include polyamide of formula X / Y, Ar in which:

Y represents the residues of an aliphatic diamine having from 8 to 20 carbon atoms,

Ar refers to the residues of an aromatic dicarboxylic acid,

X denotes either the residues of the aminoundecanoic acid NH 2 - (CH 2) 10 COOH, lactam 12 or the corresponding amino acid or the unit Y, x remains of the condensation of the diamine with an aliphatic diacid (x) having between 8 and 20 carbon atoms is still the unit Y ₁ I remains of the condensation of the diamine with isophthalic acid,

Advantageously, the inherent viscosity of the copolyamide is between 0.5 and 2 and preferably between 0.8 and 1.8. The advantage of these polyamides is the low water uptake which does not exceed 3.5% and advantageously 3% by weight. Preferably XJ Y ₁ Ar designates:

- 11/10, T which results from the condensation of aminoundecanoic acid, 1,10-decanediamine and terephthalic acid, - 12 / 12.T which results from the condensation of lactam 12, the 1, 12-dodecanediamine and terephthalic acid,

10,10 / 10, which results from the condensation of sebacic acid, 1,10-decanediamine and terephthalic acid,

- 10, 1/10, T which results from the condensation of isophthalic acid, 1, 10-decanediamine and terephthalic acid.

Other polyamides which can be used include, for example, polyamides A1 of formula X.Y / Z or 6.Y2 / Z, in which:

X represents the residues of an aliphatic diamine having from 6 to 10 carbon atoms, Y denotes the residues of an aliphatic dicarboxylic acid having from 10 to 14 carbon atoms, Y2 denotes the residues of an aliphatic dicarboxylic acid having from 15 to 20 carbon atoms,

Z denotes at least one unit chosen from the residues of a lactam, the residues of an alpha-omega amino carboxylic acid, the X1.Y1 unit in which X1 denotes the residues of an aliphatic diamine and Y1 denotes the remains of a aliphatic dicarboxylic acid, the weight ratios Z / (X + Y + Z) and Z / (6 + Y2 + Z) being between 0 and 15%.

As a variant, said inner layer may be based on at least one thermoplastic polymer chosen from the group consisting of fluorinated polymers, such as homopolymers and copolymers of vinylidene fluoride (PVDF), polyketones, polymethylmethacrylates of methyl

(PMMA), phenylene polysulfides (PPS), polyphenylene oxides

(PPO), ethylene / vinyl alcohol copolymers (EVOH), polyvinyl chlorides (PVC), polyethylenes and polypropylenes.

As examples of fluoropolymer, a polymer chosen from:

the homo- and copolymers of vinylidene fluoride (VDF) preferably containing at least 50% by weight of VDF, the copolymer being chosen from chlorotrifluoroethylene (CTFE), hexafluoropropylene (HFP), trifluoroethylene (VF3) and the tetrafluoroethylene (TFE), homo- and copolymers of trifluoroethylene (VF3), copolymers, and especially terpolymers, combining the residues of the chlorotrifluoroethylene (CTFE), tetrafluoroethylene (TFE), hexafluoropropylene (HFP) and / or ethylene units and, if appropriate, VDF and / or VF3.

Mention may also be made of copolymers of ethylene and tetrafluoroethylene (ETFE).

Advantageously, the fluoropolymer is polyvinylidene fluoride (PVDF), homopolymer or copolymer. Preferably, the PVDF contains, by weight, at least 50% of VDF, more preferably at least 75% and better still at least 85%. The comonomer is advantageously ¹ HFP.

Advantageously, the thermistor can be connected to the voltage source by a plurality of conductive elements which are selectively connected to the voltage source to affect the response time of the thermistor.

In general, the textile web may be textured and made of a material such as polyamide or polyester for example, and each conductive element may be arranged spirally, longitudinally or transversely in the textile web.

According to one embodiment of the invention, the material forming the thermistor can be coated on the textile web in the form of a paint layer and on a small thickness of less than 1 mm, this material being a conductive polymeric composite material. A fluid transport tube according to the invention can be used in many fields of industry, particularly in the automotive field for injecting a fluid such as urea to act on the nitrogen monoxides present in the gases of the invention. exhaust of a motor vehicle, in the aerial area to freeze a fluid such as water in the hold of an aircraft, or in the field of swimming pools to freeze the water of a pool, for example .

Other advantages, characteristics and details of the invention will emerge from the additional description which follows with reference to the accompanying drawings, given solely by way of example and in which: - Figure 1 is a partial cutaway view of a fragment of a fluid transport tube according to the invention and comprising an intermediate device for thermal regulation;

FIG. 2 is a partial schematic view of the intermediate thermal regulation device of FIG. 1; FIG. 3 is a schematic view of an alternative embodiment of the thermal regulation device of FIG. 1; and FIG. 4 is a simplified view of a method of using a fluid transport tube according to the invention in an application for treating the exhaust gases of a motor vehicle.

According to one embodiment of the invention, the tube 1 for transporting a fluid comprises at least one inner layer 3 which is in contact or not with the transported fluid and an outer protective layer 5. The inner layer 3 is generally made of a non-electrically conductive material and compatible with any aggression of the transported fluid. The outer layer 5 of protection tube 1 must be able to withstand the possible aggressiveness of the surrounding environment and be made of a material having good thermal insulation properties, this material may be EPDM based for example.

The tube 1 also comprises an intermediate thermal regulation device 10 which is connected to a voltage source not shown in FIG. 1. This thermal regulation device 10 comprises a thermistor 12 with a positive temperature coefficient whose electrical resistance is self-controlled. by temperature (PTC effect). Specifically, the thermistor 12 is characterized by a variable resistance that increases significantly from a critical temperature or threshold. If a voltage is applied across the thermistor at a temperature of the order of 0 ^° C for example, the current flowing through it will heat the thermistor by Joule effect. When the temperature reaches a threshold value T ₀ , the resistance of the thermistor will increase strongly so that any increase in temperature above T ₀ will cause a decrease in the current flowing through the thermistor and therefore a decrease in the power consumed. by Joule effect. On the other hand, any decrease in the temperature below T ₀ will result in an increase in the current flowing through the thermistor and therefore an increase in power consumed by the Joule effect. In other words, a self-control of the power dissipated by the thermistor in the vicinity of its threshold temperature T ₀ is thus obtained. The thermistor 12 is connected to the voltage source by at least two conductive elements 14 and 15 which provide the current necessary for heating the thermistor. Each conductive element

14 and 15, in the form of a wire for example, is supported by a textile web 17 in the form of a braid advantageously textured to give it a certain volume. The textile web 17 may be made of polyamide or polyester, for example, and is wound on the inner layer 3 of the tube. According to the embodiment of FIG. 1, the conducting elements 14 and

15 are arranged spirally in the textile web 17 but, alternatively, these conductive elements could extend either longitudinally in a direction parallel to the axis of the tube, or transversely in a direction perpendicular to the axis of the tube.

The thermistor 12 is made of a conductive polymeric composite material, such a material 19 being described in particular in the European patent application published under the number EP-1 205 514. By way of example, this material 19 may comprise by weight of 40 to 90% of PVDF homopolymer or crystallized copolymer in β-form, from 10 to 60% of a conductive filler, carbon black or graphite, for example, from 0 to 40% of a crystalline or semi-crystalline polymer, and from 0 to 40% of a charge different from the previous one, the aforementioned β-shaped crystals being nucleated on the surface of the particles of the conductive filler. This conductive polymeric composite material 19 is coated on the textile web 17 in the form of a paint layer with a small thickness of less than 1 mm and preferably of the order of a few tenths of a millimeter. This thickness corresponds globally to 100g of the coated material on one square meter.

As illustrated in FIG. 2, the two conductive elements 14 and 15 are spirally arranged in the textile ply 17 and connected to the two terminals of a voltage source V, and the current passages are made in the material 19 according to FIGS. transverse directions materialized by the arrows F between the two conducting elements 14 and 15 separated from each other by a distance D, assuming that the two conductive elements are wound in the braid 12 with a constant pitch P (P = D x 2) and spaced from each other by a constant distance.

Thus, when a voltage V is applied between the two conductors 14 and 15, a current I flows in the material 19 and an electric power P will propagate in this material 19 by Joule effect P = Rl ² (R being the electrical resistance of the material), and in particular to dissipate towards the inner layer 3 of the tube for heating the fluid transported by the tube 1. If the tube 1 is in an environment at a low temperature T ₁ below 0 ⁰ C for example, the electrical resistance R of the material 19 will be low which has the effect of increasing the current I and thus the power P dissipated, with a consequent rise in the temperature of the transported fluid to put it off frost. When the temperature of the material 19 exceeds the threshold value T ₀ from which its electrical resistance R increases, the current I decreases and thus the power dissipated, so that we obtain a self-control of the power dissipated by the material 19 around the threshold value T ₀ . If, on the other hand, the tube 1 is in an environment at a temperature T _{2 that is} significantly greater than the threshold value T ₀ of the material 19, the dissipated power will be low and will have no effect on the value of the temperature T ₂ . However, in the context of the invention, it is the first hypothesis or setting frost that is preferred, namely a tube 1 placed in a low temperature environment to increase the temperature of the fluid to ensure that its viscosity is sufficient to obtain a good flow of the fluid in the tube 1. However, as shown in Figure 3, it is advantageous to provide a plurality of conductive elements 14 and conductive elements 15 to reduce the response time 19. Increasing the number of conductive elements 14 and 15 decreases the distance Di between two conductors 14 and 15, and this results in greater heat dissipation to heat the fluid faster. Thus, it can be expected to connect more conductive elements 14 to the terminal + and more elements conductors 15 to the terminal - of the voltage source V, in particular to increase the power dissipated by the material 19 and reach more quickly the value of its threshold temperature T ₀ .

For example, a tube 1 according to the invention carrying urea may be used to treat the nitrogen oxides of the exhaust gases of a motor vehicle, as is schematically illustrated in FIG. containing urea is connected to an injection pump 22 which communicates with the exhaust pipe 24 by a tube 1 according to the invention. At the cold start of the engine, the voltage source that will supply power to the two conductor elements 14 and 15 of the tube is the battery 26 of the vehicle, and it will result in a power dissipation by the material 19 which may be more or less important depending on the temperature of the urea at the start of the engine.

A tube 1 according to the invention carrying water, for example, can also be used to maintain this water frost in an aircraft hold or in a swimming pool.

The tube 1 according to the invention could also have another structure than that illustrated in Figure 1, that is to say include additional layers without departing from the scope of the invention, depending on the intended applications.

By way of example, the inner layer 3 of the tube 1 may have a thickness of between 1 and 10 mm, the outer layer 5 a thickness of between 1 and 50 mm and the inside diameter of the tube 1 may be between 5 and 500 mm, depending on the applications envisaged.

Claims

A fluid transport tube comprising at least one inner layer (3), an outer protective layer (5), and an intermediate thermal regulation device (10) connected to a voltage source and adapted to heat the fluid transported to an equilibrium or setpoint temperature using a thermistor (12) with a positive temperature coefficient whose electrical resistance is self-controlled by the temperature and which is connected to the voltage source (V) by at least two conductive elements ( 14, 15) which provide the current necessary for its heating, characterized in that each conductive element (14, 15) is a wire which is supported by a textile web (17) wound around the inner layer (3) of the tube and in that said inner layer (3) is based on: at least one thermoplastic polymer, and / or at least one thermoplastic elastomer selected from the group consisting of thermoplastic polyurethanes asics, ether / ester copolymers, ether / amide copolymers and mixtures of ethylene or propylene with an uncrosslinked ethylene / propylene copolymer.

The fluid transport tube according to claim 1, wherein the thermistor (12) is connected to the voltage source (V) by a plurality of conductive elements (14, 15) which are selectively connected to the voltage source (V). to play on the response time of the thermistor (12).

3. Fluid transport tube according to claim 1 or 2, wherein the textile web (17) is a braid made of a material such as polyamide or polyester for example.

The fluid transport tube according to claim 2 or 3, wherein each conductive member (14, 15) is spirally disposed in the textile web (17).

The fluid transport tube according to claim 2 or 3, wherein each conductive element (14, 15) is longitudinally disposed in the textile web (17).

The fluid transport tube according to claim 2 or 3, wherein each conductive element (14, 15) is transversely disposed in the textile web (17).

7. Fluid transport tube according to one of the preceding claims, wherein the material forming the thermistor (12) is deposited on the textile web (17) in the form of a paint layer.

8. fluid transport tube according to claim 7, wherein the material (19) forming the thermistor (12) is deposited on a thin less than 1mm.

The fluid transport tube according to claim 7 or 8, wherein the material (19) forming the thermistor (12) is a conductive polymeric composite material.

10. Fluid transport tube according to one of the preceding claims, wherein the outer protective layer (5) has good thermal insulation properties, and the intermediate device (10) thermal control is realized in the form of a conductive polymeric composite material (19) coated on a textile web (17) wound around the tube inner layer (3) and supporting at least two conductive elements (14, 15) connected to the voltage source (V) for supply the current required for heating the composite material (19).

11. Fluid transport tube according to claim 10, characterized in that said inner layer (3) is based on at least one thermoplastic polymer of the polyamide type and / or at least one thermoplastic elastomer of the ether / copolymer type. amide.

12. Transport tube according to claim 10, characterized in that said inner layer (3) is based on at least one thermoplastic polymer selected from the group consisting of fluorinated polymers, such as homopolymers and copolymers of vinylidene fluoride polycetones, polymethyl methacrylates, phenylene polysulfides, polyphenylene oxides, ethylene / vinyl alcohol copolymers, polyvinyl chlorides, polyethylenes and polypropylenes.

13. Use of a fluid transport tube as defined by one of the preceding claims, characterized in that it is used to inject urea into an engine exhaust pipe to act on the monoxides of nitrogen present in the exhaust gas.

14. Use of a fluid transport tube as defined by one of claims 1 to 13, characterized in that it is used to de-gel a fluid such as water in an aircraft hold or in a pool.