FR2993893A1 - Urea tank manufactured from a polymer composition including an aromatic polyamide that comprises a number of final amine groups equal or higher than a number of final carboxyl groups, useful for a freight vehicle e.g. lorry - Google Patents

Abstract

Urea tank manufactured from a polymer composition including an aromatic polyamide, is claimed. The aromatic polyamide comprises a number of final amine groups equal or higher than a number of final carboxyl groups, and has an inherent viscosity of 0.90 dl/g as measured by standard ASTM D-5225.

Description

The present invention relates to the field of storage containers and injection systems for fluid reservoirs of motor vehicles and more particularly to storage containers for the filling of vehicles. a tank with a solution of urea. The invention further relates to injection systems for conveying the urea solution from the urea reservoir to the flue gas exhaust line for use in vehicle emission control systems, for vehicles equipped with diesel engines. In general, this type of transport vehicle comprises a body mounted on wheels. It is also equipped with a diesel tank, for fueling the fuel in the engine of said vehicle. Anti-pollution systems have become very widespread on motor vehicles for the purpose of reducing their polluting emissions. Such anti-pollution systems are now required for the majority of vehicles.

Nevertheless, environmental standards have lowered the maximum acceptable level of emissions of nitrogen compounds (N0x). A catalytic converter alone is insufficient to obtain such a reduction in emissions of these compounds. Selective Catalytic Reduction (SNCR) or Selective Catalytic Reduction (SCR) are proven processes for controlling nitrogen oxide (N0x) emissions from exhaust from diesel vehicles. These processes involve the injection into the catalytic converter of a solution which results from a mixture of urea or ammonia and water to generate redox reactions with the nitrogen-containing compounds, causing the decomposition of certain harmful pollutants. The most widely used process uses a solution of urea in water, called AUS32® or AdBlue®, a trademark owned by the German Association of the Automotive Industry.

However, transporting a solution of urea in a motorized vehicle is difficult because of the sensitivity of the solution to temperature: the solution decomposes above 75 ° C, giving ammonia, and freezes at -11.5 ° C, with solidification of the solution leading to the expansion of its volume. The tanks used for the transport of the solution must therefore be chemically resistant and retain their mechanical properties for a long time, ideally during the life of the vehicle.

The urea tanks according to the prior art were made of polyolefins or aliphatic polyamides. US2007246411 discloses a pollution abatement device comprising a depollution fluid reservoir connected by a pipe to an injector element for injecting the fluid into a catalyst of a flue gas exhaust pipe. The reservoir contains a depollution fluid comprising a mixture of urea and water respectively in proportions of about 30 percent and 70 percent. The pipe includes an inner tube extending coaxially inside the outer tube. The disclosed tubes are made of materials chosen from: thermoplastic materials, for example polypropylene and ethylene-propylene-diene monomer, elastomeric materials, for example based on silicone, polyethylene, polyamides, a mixture of polypropylene and ethylenepropylene-diene monomer, and polyethylene grafted with maleic anhydride. Polyphthalamides offer an improvement over aliphatic polyamides such as PA66 in continuous contact with the urea solution. This having been specified, the present invention aims to improve the solutions of the prior art by providing an improved urea reservoir and urea injection system, manufactured at from a certain class of polyamides, aromatic polyamides and, in particular, polyphthalamides. The present invention thus relates to: an improved urea reservoir for a transport vehicle, and an improved urea injection system or device used in a urea injection system, made of a composition (C) of polymers comprising an aromatic polyamide (A), the aromatic polyamide (A) having an amine terminal number equal to or greater than the number of carboxyl end groups and having an inherent viscosity of at least 0.90 dl / g as measured by ASTM D-5225.

Other aspects of the present invention relate to a unit comprising a diesel tank and the urea tank mentioned above or a device used in a urea injection system, and a transport vehicle comprising said unit. The term "urea reservoir" used herein is intended to mean any container containing an aqueous solution of urea, typically used in a selective reduction system embedded in transport vehicles. The present invention can be applied to any type of motorized vehicle and, in particular, to trucks, private cars, etc. The term "device used in a urea injection system" used herein is intended to refer to any pipe, pump, tube, fitting used to convey the urea solution from the urea reservoir into the conduit. exhaust gas burned. The urea reservoir and the urea injection system according to the present invention are made of a polymer composition (C) comprising a polyamide (A) as detailed above. Aromatic Polyamide (A) The term "polyamide" is generally understood to mean a polymer comprising repeating units derived from the polycondensation reaction of at least one diamine and at least one dicarboxylic acid and / or from minus an aminocarboxylic acid or a lactam. For the purpose of the present invention, the term "aromatic polyamide" is intended to mean a polyamide which comprises more than 35 mol% of aromatic repeating units, preferably more than 45 mol%, more preferably more than 55 mol%. mole, more preferably more than 65 mol% and most preferably more than 75 mol%. For purposes of the present invention, the term "aromatic repeating unit" is intended to mean any repeating unit which comprises at least one aromatic group. The aromatic repeating units may be formed by the polycondensation of at least one aromatic dicarboxylic acid with a diamine or by the polycondensation of at least one dicarboxylic acid with an aromatic diamine. Suitable dicarboxylic acids may be aromatic or aliphatic. For purposes of the present invention, the term "aromatic" when referring to a dicarboxylic acid or a diamine means that said acid or diamine comprises one or more aromatic groups.

Derivatives of dicarboxylic acids, such as acid halides, particularly chlorides, acid anhydrides, acid salts, acid amides and the like, can be advantageously used in the polycondensation reaction.

Non-limiting examples of aromatic dicarboxylic acids include phthalic acids, including isophthalic acid (AI), terephthalic acid (AT) and orthophthalic acid (AO), naphthalenedicarboxylic acids (including acid 2,6-naphthalenedicarboxylic acid, 2,7-naphthalenedicarboxylic acid, 1,4-naphthalenedicarboxylic acid, 2,3-naphthalenedicarboxylic acid, 1,8-naphthalenedicarboxylic acid and 1,2-naphthalenedicarboxylic acid ), 2,5-pyridinedicarboxylic acid, 2,4-pyridinedicarboxylic acid, 3,5-pyridinedicarboxylic acid, 2,2-bis (4-carboxyphenyl) propane, bis (4-carboxyphenyl) methane 2,2-bis (4-carboxyphenyl) hexafluoropropane, 2,2-bis (4-carboxyphenyl) ketone, 4,4'-bis (4-carboxyphenyl) sulfone, 2,2-bis (3- carboxyphenyl) propane, bis (3-carboxyphenyl) methane, 2,2-bis (3-carboxyphenyl) hexafluoropropane, 2,2-bis (3-carboxyphenyl) ketone, bis (3-carboxyphenoxy) benzene. Nonlimiting examples of aliphatic dicarboxylic acids include oxalic acid (HOOC-COOH), malonic acid (HOOC-CH 2 -COOH), succinic acid [HOOC- (CH 2) 2 -COOH], glutaric acid [HOOC- (CH2) 3-COOH], 2,2-dimethylglutaric acid [HOOC-C (CH3) 2- (CH2) 2-COOHL adipic acid [HOOC- (CH2) 4-COOH] , 2,4,4-trimethyladipic acid [HOOC-CH (CH3) -CH2-C (CH3) 2 -CH2-COOHL pimelic acid [HOOC- (CH2) 5_C00H], suberic acid [HOOC- (CH2) 6-COOH], azelaic acid [HOOC- (CH2) 7-COOH], sebacic acid [HOOC- (CH2) 8-COOH], undecanedioic acid [HOOC- (CH2) 9- COOH], dodecanedioic acid [HOOC- (CH2) 10 -COOH], tetradecanedioic acid [HOOC- (CH2) 11-COOH], cis-cyclohexane-1,4-dicarboxylic acid and / or cyclohexane-1,4-dicarboxylic acid and cis-cyclohexane-1,3-dicarboxylic acid and / or trans-cyclohexane-1,3-dicarboxylic acid. According to the preferred embodiments of the present invention, the aromatic polyamide (A) advantageously comprises repeating units derived from at least one dicarboxylic acid chosen from the group consisting of phthalic acids, for example isophthalic acid (AI), terephthalic acid (AT), orthophthalic acid (AO), adipic acid, naphthalenedicarboxylic acids, sebacic acid and azelaic acid, phthalic acids being preferred. One or more of said phthalic acids may be used. Phthalic acid is preferably terephthalic acid, optionally in combination with isophthalic acid. Suitable diamines for the aromatic polyamide (A) may be aromatic or aliphatic. Suitable aliphatic diamines are typically aliphatic alkylenediamines having 2 to 18 carbon atoms. Said aliphatic alkylenediamine is advantageously selected from the group consisting of 1,2-diaminoethane, 1,2-diaminopropane, propylene-1,3-diamine, 1,3-diaminobutane, 1,4-diaminobutane, , 5-diaminopentane, 1,4-diamino-1,1-dimethylbutane, 1,4-diamino-1-ethylbutane, 1,4-diamino-1,2-dimethylbutane, 1,4-diamino-1,3 dimethylbutane, 1,4-diamino-1,4-dimethylbutane, 1,4-diamino-2,3-dimethylbutane, 1,2-diamino-1-butylethane, 1,6-diaminohexane, 1, 7-diaminoheptane, 1,8-diaminooctane, 1,6-diamino-2,5-dimethylhexane, 1,6-diamino-2,4-dimethylhexane, 1,6-diamino-3,3- dimethylhexane, 1,6-diamino-2,2-dimethylhexane, 1,9-diaminononane, 2-methylpentamethylenediamine, 1,6-diamino-2,2,4-trimethylhexane, 1,6-diamino-2 , 4,4-trimethylhexane, 1,7-diamino-2,3-dimethylheptane, 1,7-diamino-2,4-dimethylheptane, 1,7-diamino-2,5-dimethylheptane, 1,7 -diamino-2,2-dimethylheptane, 1,10-decanediamine e, 1,8-diamino-1,3-dimethyloctane, 1,8-diamino-1,4-dimethyloctane, 1,8-diamino-2,4-dimethyloctane, 1,8-diamino-3, 4-dimethyloctane, 1,8-diamino-4,5-dimethyloctane, 1,8-diamino-2,2-dimethyloctane, 1,8-diamino-3,3-dimethyloctane, 1,8-diaminoctane 4,4-dimethyloctane, 1,6-diamino-2,4-diethylhexane, 1,9-diamino-5-methylnonane, 1,11-diamino-undecane, 1,12-diaminododecane, 1,3 diaminocyclohexane, 1,4-diaminocyclohexane, 1,3-bis (aminomethyl) cyclohexane, 1,4-bis (aminomethyl) cyclohexane, bis (3-methyl-4-aminocyclohexyl) methane, 4,4 methylenebiscyclohexylamine, isophoronediamine.

Non-limiting examples of suitable aromatic diamines include the diamines selected from the group consisting of meta-phenylenediamine, meta-xylylenediamine and para-xylylenediamine. According to preferred embodiments of the present invention, the aromatic polyamide (A) advantageously comprises repeating units derived from at least one diamine selected from the group consisting of diamines comprising between 4 and 12 carbon atoms. More preferably, the diamine is selected from the group consisting of 1,6-diaminohexane, 1,8-diaminooctane, 1,9-diaminononane, 1,10-decanediamine, 1,11-diamino-undecane 1,12-diaminododecane, meta-xylylenediamine. Even more preferably, the diamine is selected from the group consisting of 1,6-diaminohexane, 1,9-diaminononane, 1,10-decanediamine, metaxylylenediamine. In a preferred embodiment, the aromatic polyamide (A) according to the present invention is formed by reacting a mixture comprising less than 20 mol% of adipic acid, based on the total amount of dicarboxylic acid. Preferably, it is formed by reaction of a mixture comprising less than 18 mol%, more preferably less than 15 mol%, even more preferably less than 13 mol% of adipic acid based on the total amount of dicarboxylic acid. In a particular embodiment, it is preferably formed by reaction of a mixture essentially free or even completely free of adipic acid. Excellent results were obtained when the aromatic polyamide (A) was a polyphthalamide consisting essentially of repeating units formed by the polycondensation reaction between terephthalic acid, hexamethylenediamine, adipic acid and isophthalic acid, also called PA 6T / 6I / 66. Good results were obtained with the same polymer comprising the recurring units 6T / 6I / 66 in the following range: 55 to 75 mol% 6T, 15 to 35 mol% of 61 and 5 to 15 mol% of Recurring units 66. Most preferably, PA 6T / 6I / 66 has the following proportion: 65/25/10. Similarly, very good results have been obtained when the aromatic polyamide (A) was a polyphthalamide consisting essentially of repeating units formed by the polycondensation reaction between terephthalic acid, hexamethylenediamine and isophthalic acid, also called PA 6T / 6I, especially when PA 6T / 6I comprised 60 to 80 mol% of 6T, 20 to 40 mol% of recurring units 61. Most preferably PA 6T / 6I has the following proportion: 70 / 30. The aromatic polyamide (A) of the present invention may be selected from the copolymer of terephthalic acid and isophthalic acid with hexamethylenediamine (PA 6T / 6I), the copolymer of terephthalic acid with hexamethylenediamine and 2-methyl-1,5-pentadiamine (PA 6T / DT); the copolymer of terephthalic acid with hexamethylenediamine and decamethylenediamine (PA 6T / 10T); the copolymer of terephthalic acid and isophthalic acid with hexamethylenediamine and decamethylenediamine (PA 6T / 61 / 10T / 101); the copolymer of terephthalic acid with hexamethylenediamine and 11-aminoundecanoic acid (PA 6T / 11); the copolymer of terephthalic acid with decamethylenediamine and 11-amino-undecanoic acid (PA 10T / 11); the copolymer of hexamethylenediamine with terephthalic acid and 2,6-napthalenedicarboxylic acid (PA 6T / 6NDA); the copolymer of hexamethylenediamine with terephthalic acid and sebacic acid (PA6T / 6,10); the copolymer of hexamethylenediamine with terephthalic acid and 1,12-diaminododecanoic acid (PA 6T / 12T); the copolymer of hexamethylenediamine with terephthalic acid, isophthalic acid and adipic acid (PA 6T / 6I / 66); the copolymer of nonamethylenediamine with terephthalic acid (PA 9T); the copolymer of decamethylenediamine with terephthalic acid (PA 10T); the copolymer of undecamethylenediamine with terephthalic acid (PA 11T) and the copolymer of dodecamethylenediamine with terephthalic acid (PA 12T). The aromatic polyamide (A) according to the present invention may also be terminally blocked by any terminal blocking agent.

The term "terminal blocking agent" denotes one or more compounds that react with the ends of a polycondensation product, blocking the ends and limiting the molecular weight of the polymer. The terminal blocking agent is typically selected from the group consisting of an acid comprising a single reactive carboxylic acid group [acid (MA)] and an amine comprising a single reactive amine group [amine (MN)] and their mixtures. The term "acid / amine comprising a single carboxylic acid / reactive amine group" is intended to encompass not only monocarboxylic acids or monoamines but also acids comprising more than one carboxylic group or derivative thereof and amines comprising more than one amine or a derivative thereof but, but in which only one of said carboxylic acid / amine groups has a reactivity with respect to the polycondensation product obtained by the polycondensation of the diamine (s) and diacid (s) mentioned above. The term 'derivative thereof' used in combination with the term 'carboxylic acid' or 'amine' is intended to mean any derivative which is capable of reacting under conditions of polycondensation to give an amide bond.

Among the suitable [acid (MA)], mention may be made especially of acetic acid, propionic acid, butyric acid, valeric acid, caproic acid, caprylic acid, lauric acid, lactic acid and the like. stearic acid, cyclohexanecarboxylic acid and benzoic acid. The acid (MA)] is preferably selected from acetic acid, benzoic acid and mixtures thereof. Among the suitable [amines (MN)], mention may be made especially of methylamine, ethylamine, butylamine, octylamine, aniline, toluidine, propylamine, hexylamine, dimethylamine and cyclohexylamine. The endblocking agent is generally used in an amount of more than 0.1 mol%, preferably more than 0.5 mol%, even more preferably greater than 0.8 mol%, based on the total number of moles of dicarboxylic acids, if [acid (MA)] is used as a terminal blocking agent or on the basis of the total number of diamines, if [amines (MN)] are used as the endblocking agent. The endblocking agent is generally used in an amount of less than 6.0 mol%, preferably less than 5.5 mol%, even more preferably less than 5.0 mol%, more preferably less than 4.5 mol%, based on the total number of moles of the dicarboxylic acids, if [acid (MA)] is used as a terminal blocking agent or on the basis of the total number of diamines, if [amines ( MN)] are used as a terminal blocking agent. The aromatic polyamide (A) of the present invention has at least one melting temperature as measured by DSC (Differential Scanning Calorimetry - Differential Scanning Calorimetry) according to IS0-11357-3, of more than 250 ° C, more preferably more than 270 ° C, still more preferably greater than 280 ° C, most preferably more than 290 ° C. The melting temperature of the aromatic polyamide (A) of the present invention is preferably less than 340 ° C, more preferably less than 330 ° C, most preferably less than 335 ° C. The aromatic polyamide (A) has an inherent viscosity of at least 0.90 dl / g, preferably at least 0.91, more preferably at least 0.92 dl / g as measured according to ASTM D-5225. The aromatic polyamide (A) of the present invention has an amine terminal number equal to or greater than the number of carboxyl end groups, in other words, the aromatic polyamide (A) is "amine rich".

In the aromatic polyamide (A), the number of amine terminal groups is generally at least 40 μg / g, preferably at least 50 μg / g, more preferably at least 60 μg / g. and more preferably at least 70 μg / g, still more preferably at least 80 μg / g and most preferably at least 90 μg / g. In the aromatic polyamide (A), the number of carboxyl end groups is generally at most 80 μg / g, preferably at most 75 μg / g, more preferably at most 70 μg / g. g, more preferably still not more than 65 i.teq / g, still more preferably not more than 60 i.teq / g and most preferably not more than 55 i.téq / g. The aromatic polyamide (A) advantageously comprises a total number of carboxyl and amine end groups equal to or less than 180 μg / g, more preferably less than 175 μg / g, even more preferably less than 170 μg / g. more preferably still less than 165 i.teq / g, still more preferably less than 160 i.teq / g, still more preferably less than 158 i.téq / g and most preferably less than 155 i.téq / g. The Applicant has surprisingly found that the polyamide (A) having a number of amine terminal groups equal to or greater than the number of carboxyl end groups, as indicated above, has a high chemical and thermal resistance with respect to aggressive basic environments. Once the polyamide (A) is suitably mixed in a composition (C), as mentioned below, this particular number of amine end groups, as indicated above, is particularly advantageous for the obtaining a composition (C) having the properties required for use in the manufacture of urea reservoirs or urea injection systems. According to the present invention, the number of amine terminal groups is advantageously greater than the number of carboxyl end groups in an amount of at least 5 μg / g, of at least 7 μg / g, of at least 9 i.teq / g, of not less than 10 i.teq / g, of not less than 15 i.teq / g, of not less than 20 i.teq / g, not less than 25 i.téq / g at least 30 μg / g, of not less than 35 μg / g, of not less than 40 μg / g, of not less than 45 μg / g, of not less than 50 i.téq / g. According to the present invention, the polyamide (A) advantageously comprises 0 to 80 μg / g of carboxyl end groups, preferably 5 to 55 μg / g of carboxyl end groups. The total number of carboxyl and amine end groups in the polyamide (A) of the present invention is suitably determined by a titration method, preferably a potentiometric titration method. The polyamide (A) is generally dissolved in a suitable solvent for the titration. Non-limiting examples of suitable solvents and solvent mixtures for use in the titration of the polyamides (A) of the present invention for the determination of the total number of carboxyl end groups are, for example, o-cresol and o-cresol / chloroform. Formaldehyde is generally added to react with the amine end groups to appropriately remove salt formation between the carboxyl and amine end groups. Nonlimiting examples of solvents and solvent mixtures suitable for use in the titration of the polyamides (A) of the present invention for the determination of the total number of amine end groups are, for example, phenol / methanol, phenol / ethanol and hexafluoroisopropanol. For the determination of the total number of carboxyl end groups, a base is suitably used as the titrant. Suitable bases are generally those having a Kb value equal to, or at least 1000 times more than the Kb value of the deprotonated carboxyl terminal group. Non-limiting examples of suitable bases include alkali metal hydroxides such as sodium hydroxide, potassium hydroxide, lithium hydroxide, cesium hydroxide, alkaline earth metal hydroxides such as calcium hydroxide, barium hydroxide, magnesium hydroxide, strontium hydroxide and basic alkali metal salts such as sodium carbonate, sodium hydrogencarbonate, potassium carbonate and hydrogencarbonate of potassium. Preferred bases are sodium hydroxide and potassium hydroxide. The most preferred base is potassium hydroxide.

The base is generally present as an aqueous solution or a solution of the base in an organic solvent. The organic solvent to be used may, for example, be dimethylformamide, dimethylacetamide, dimethylsulfoxide, sulfolane, tetrahydrofuran, acetonitrile, dioxane, methanol, ethanol. Of these, methanol is particularly preferred.

For purposes of the present invention, the term "aqueous solution" refers to solutions of water-soluble compounds, for example, salt water or any other aqueous solution of mineral salt. For amine terminal groups, an acid is suitably used as a titrant. Suitable acids are generally those having a Ka value equal to or at least 1000 times higher than the Ka value of the protonated amino terminal group. Non-limiting examples of acids include hydrochloric acid. In addition, some other analytical methods can be used to determine the number of carboxyl and amine end groups in said polyamide (A), including in particular spectrometric measurements such as IR and NMR or radioactive measurements such as for polymers having labeled end groups. Suitable aromatic polyamides (A) are especially available under the names AMODEL® PPA from Solvay Specialty Polymers United States, LLC. The aromatic polyamide (A) of the present invention can advantageously be prepared by standard techniques in which the monomers react together. in a polycondensation process where the intrinsic viscosity of the melt of the synthesized polymer is controlled by methods known in the art (such as setting reaction time, using specific proportions of monomers, using terminal blocking , etc.). Composition (C) The composition (C) of the present invention may comprise in addition to the aromatic polyamide (A) at least one reinforcing filler. The reinforcing fillers are well known to those skilled in the art and can be added to the composition (A) according to the present invention. They are preferably chosen from fibrous and particulate fillers. More preferably, the reinforcing filler is selected from mineral fillers (such as talc, mica, kaolin, calcium carbonate, calcium silicate, magnesium carbonate), a glass fiber, a carbon fiber , a synthetic polymer fiber, an aramid fiber, an aluminum fiber, a titanium fiber, a magnesium fiber, a boron carbide fiber, a rock wool fiber, a steel fiber, wollastonite etc. Even more preferably, it is selected from mica, kaolin, calcium silicate, magnesium carbonate, fiberglass and wollastonite. More preferably, the reinforcing filler is selected from glass fiber, carbon fiber and wollastonite. A particular class of fibrous fillers is whiskers, i.e. monocrystalline fibers of various raw materials such as Al 2 O 3, SiC, BC, Fe and Ni. Of the fibrous fillers, glass fibers are preferred; they include cut glass fibers A, E, C, D, S and R, as described in chapter 5.2.3, pages 43-48 in Additives for Plastics Handbook, 2nd edition, John Murphy. Preferably, the filler is selected from fibrous fillers. In a preferred embodiment of the present invention, the reinforcing filler is selected from wollastonite and fiberglass. Excellent results have been obtained when using wollastonite and / or glass fibers. The glass fibers may have a round cross section or a non-circular cross section. The weight percentage of the reinforcing filler in the total weight of the composition (C) according to the present invention is generally at least 5% by weight, preferably at least 10% by weight, more preferably at least 15% by weight and the more preferably at least 20% by weight. In addition, the weight percentage of the reinforcing filler in the total weight of the composition (C) is generally at most 80% by weight, preferably at most 70% by weight and most preferably at most 65% by weight. Depending on the nature of the object to be used in the injection system, the amount of reinforcing filler may range from 50 to 65% by weight or from 25 to 45% by weight or from 0 to 10% by weight. weight, based on the total weight of the composition (C). When the object is a urea container, high strength is required and therefore the reinforcing filler could be used in an amount as high as 65% by weight, based on the total weight of the composition (C). In other applications, such as flexible conveying conduits used to transport urea from the urea container to the flue gas exhaust line, very small amounts of reinforcing filler are tolerated in the composition (C) in order to maintain the flexibility of the finished object. The weight percentage of the aromatic polyamide (A) in the total weight of the composition (C) is generally at least 30% by weight, preferably at least 40% by weight and more preferably at least 50% by weight. weight. In addition, the weight percentage of the aromatic polyamide (A) in the total weight of the composition (C) is generally at most 95% by weight, preferably at most 80% by weight and most preferably not more than 60% by weight. The composition (C) of the present invention may comprise other polyamides, in addition to the aromatic polyamide (A). The composition (C) of the present invention may comprise at least two aromatic polyamides (A) or it may comprise other polyamides such as aliphatic polyamides such as PA6, PA66, PA12, etc. The composition (C) of the invention may optionally comprise additional components such as stabilizing additives, especially demoulding agents, impact modifiers, plasticizers, lubricants, heat stabilizers, light stabilizers and the like. antioxidants, etc. The compositions (C) in another preferred embodiment further comprises at least one stabilizing additive. The stabilizing additive may be present in an amount of 0.1 to 5% by weight. The levels of these additional optional additives will have to be determined for the particular use envisaged in the urea injection system or in the urea reservoir, generally levels up to 30% by weight, preferably up to 10% by weight. % by weight, more preferably up to 5% by weight and even more preferably up to 2% by weight (based on the total weight of the polymer composition) of such additional additives being considered to be within the range of practice ordinary in the extrusion technique. The composition (C) may further contain one or more UV absorbers selected from the group consisting of s-triazines, oxanilides, hydroxybenzophenones, benzoates and α-cyanoacrylates. Thermal stabilizers may also be included in the compositions (C). Thermal stabilizers commonly used in polyamide compositions are well known in the art. They can typically be one or more of 3,9-bis [1,1-dimethyl-2 - [(3-tert-butyl-4-hydroxy-5-methylphenyl) propionyloxy] ethyl] 2,4,8, 10-tetraoxaspiro [5.5] undecane, pentaerythritol tetrakis (3- (3,5-di-tert-butyl-4-hydroxyphenyl) propionate), 3,3'-bis (3,5-di-tert-butyl) 4-hydroxyphenyl) -N, N'-hexamethylenedipropionamide, 1,3,5-tris (3,5-di- (tert) butyl-4-hydroxybenzyl) -1,3,5-triazine-2,4 , 6 (1H, 3H, 5H) -trione, 1,3,5-tris [[4- (1,1-dimethylethyl) -3-hydroxy-2,6-dimethylphenyl] methyl-1,3,5-tris triazine- - 14 - 2,4,6 (1H, 3H, 5H) -trione, 3- (1,1-dimethylethyl) -beta (1,1-dimethylethyl) -beta (1,1-ethanediyl) ester - [3- (1,1-dimethylethyl) -4-hydroxyphenyl] -4-hydroxy-b-methylpropanoic acid, bis [(3,5-bis (1,1-dimethylethyl) -4-hydroxyphenyl] methyl] butylmalonate; 2,2,6,6-pentamethyl-4-piperidyl), 2- (4,6-diphenyl-1,3,5-triazin-2-yl) -5 - ((hexyl) oxylphenol, 3 9- [2,6-bis-1,1-dimethylethyl] -4-methylphenoxy] -2,4,8,10-t traoxa-3,9-diphosphaspiro [5.5] undecane, 2,4,8,10-tetrakis (1,1-dimethylethyl) -6 - [(2-ethylhexyl) oxy] -12H-dibenzo [d, g] ] [1,3,2] dioxaphosphocine, 3,9-bis [2,4-bis (1-methyl-1-phenylethyl) phenoxy] -2,4,8,10-tetraoxa-3,9-diphosphaspiro [ 5.5] undecane, tris (2,4-di- (tert) -butylphenyl) phosphate, bis-2,4-di-tert-butylphenyl) pentaerythritol diphosphite, 3,9-bis (octadecyloxy) -2, 4,8,10-tetraoxa-3,9-diphosphaspiro [5.5] undecane, 3,9-bis [2,4-bis (1-methyl-1-phenylethyl) phenoxy] -2,4,8,10- tetraoxa-3,9-diphosphaspiro [5.5] undecane, 2- (tert-butyl) -6-methyl-4- (3 - ((2,4,8,10-tetrakis (tert-butyl) dibenzo [df] [1,3,2] dioxaphosphepin-6-yl) oxy) propyl) phenol and bis [4- (2-phenyl-2-propyl) phenyl] amine. In another particular embodiment, the composition (C) comprises a modifier of the impact resistance. Impact modifiers per se are known and are rubber-like polymers which not only contain apolar monomers such as olefins, but also polar or reactive monomers such as, among others, monomers containing functionalities. acrylate and epoxide, acid or anhydride. Examples include a copolymer of ethylene and (meth) acrylic acid or an ethylene / propylene copolymer functionalized with anhydride groups. The advantage of the impact modifiers is that they not only improve the impact resistance of the polymer composition, but they also contribute to an increase in viscosity. The rubbery polymers which can be used as impact modifiers may alternatively or additionally be defined as having a tensile modulus according to ASTM D-638 of less than about 40,000 MPa, generally less than 25,000, and preferably, less than 20,000. They may consist of random or block copolymers. Useful rubbery polymers may be prepared from reactive monomers which may be part of the polymer chains or branches, or which may be grafted onto the polymer. These reactive monomers may be dienes or carboxylic acids or their derivatives, such as esters or anhydrides. Among these rubbery polymers mention may be made of butadiene polymers, butadiene / styrene copolymers, isoprene copolymers, chloroprene copolymers, acrylonitrile / butadiene copolymers, isobutylene copolymers, isobutylene-butadiene copolymers or ethylene copolymers. propylene (EPR) and ethylene / propylene / diene copolymers (EPDM). Useful rubbery polymers include vinyl aromatic monomers, olefins, acrylic acid, methacrylic acid and their derivatives, ethylene-propylene-diene monomers and their metal salts. Some useful rubbery polymers are described in U.S. Patents 4,315,086 and 4,174,358. Suitable impact modifiers may be selected from the group consisting of ethylene / 1-octene copolymers, propylene copolymers, and the like. 1-octene, ethylene / propylene / 1-octene terpolymers, ethylene / 1-butene / 1-octene terpolymers, propylene / 1-butene / 1-octene terpolymers, ethylene / 1 terpolymers -octene / acrylonitrile, ethylene / 1-octene / methyl acrylate terpolymers, ethylene / 1-octene / vinyl acetate terpolymers, ethylene / 1-octene / methyl methacrylate terpolymers, terpolymers of ethylene / 1-octene / methyl acrylate, terpolymers of ethylene / 1-octene / vinyl acetate, terpolymers of propylene / 1-octene / acrylonitrile, propylene / 1-octene / methyl acrylate terpolymers, propylene / 1-octene / vinyl acetate terpolymers, terpolymers of propylene / 1-octene / methyl methacrylate, terpolymers of ethylene / 1-octene / 1,4-hexadiene, propylene / 1-octene / 1,4-hexadiene terpolymers, ethylene / 1-octene / ethylidene norbornene terpolymers, propylene / 1-octene / ethylidene norbornene terpolymers, copolymers ethylene-propylene copolymers, ethylene / 1-butene and ethylene / 1-hexene copolymers, ethylene / propylene / 1-butene terpolymers, ethylene / propylene / 1-hexene terpolymers, terpolymers of ethylene / propylene / 1,4-hexadiene, terpolymers of ethylene / propylene / ethylidene norbornene (EPDM), butadiene rubbers (cis-1,4-polybutadiene), butyl rubbers (TIR, rubber). isobutylene-isoprene), nitrile-butadiene rubbers (NBR, butadiene-acrylonitrile copolymers), styrene-butadiene rubbers (SBR), styrene-butadiene-styrene rubbers (SBS), styrene-ethylene rubbers butadiene-styrene (SEBS), ethylene-acrylic crosslinked rubbers (copol ymers of ethylene and methyl methacrylate), natural rubber, (cis-1,4-polyisoprene). Preferred impact modifiers are those that have been functionalized with a carboxylic acid and / or its derivative. As the carboxylic acid and / or its derivative to be used for the modification, a carboxylic acid group, a carboxylic anhydride group, a carboxylic acid ester group, a carboxylic acid metal salt group, a carboxylic acid imide group, a carboxylic acid amide group or an epoxy group may, for example, be mentioned. Examples for a compound containing such a functional group include acrylic acid, methacrylic acid, maleic acid, fumaric acid, itaconic acid, crotonic acid, methylmaleic acid, methylfumaric acid, and the like. , metaconic acid, citraconic acid, glutaconic acid, cis-4-cyclohexene-1,2-dicarboxylic acid, endocis-bicyclo [2,2,1] hepto-5-ene 2,3-dicarboxylic acid and the metal salts of these carboxylic acids, monomethyl maleate, monomethyl itaconate, methyl acrylate, ethyl acrylate, butyl acrylate, acrylate ethylhexyl, hydroxyethyl acrylate, methyl methacrylate, 2-ethylhexyl methacrylate, hydroxyethyl methacrylate, aminoethyl methacrylate, dimethyl maleate, dimethyl itaconate, maleic anhydride, itaconic anhydride, citraconic anhydride, endobicyclo [2,2,1] -5-heptene-2,3-dicarboxylic acid anhydride, maleimide, N-ethylmaleimide, N-butylmaleimide, N-phenylmaleimide, acrylamide, methacrylamide, glycidyl acrylate, glycidyl methacrylate, glycidyl ethacrylate, glycidyl itaconate and citraconate of glycidyl. The modifier of the impact strength of the composition (C) is preferably selected from the group consisting of styrene-butadiene rubbers (SBR), styrene-butadiene-styrene rubbers (SBS), styrene-ethylene rubbers -butadiene-styrene (SEBS), terpolymers of ethylene / propylene / ethylidene norbornene (EPDM) and linear low density polyethylene (LLDPE).

The weight percentage of the impact modifier in the total weight of the composition (C) is generally at least 1% by weight, preferably at least 5% by weight, more preferably at least 10% by weight, more preferably at least 15% by weight, still more preferably at least 20% by weight and most preferably at least 30% by weight. In addition, the weight percentage of the impact modifier in the total weight of the polymeric composition is generally at most 60% by weight, preferably at most 50% by weight and most preferably at least 50% by weight. at most 40% by weight. Excellent results were obtained when the impact modifier was used in an amount of 10-40% by weight, preferably 15-35% by weight, based on the total weight of the composition (C). The composition (C) can be prepared by any conventional method of preparing polyamide compositions known in the art, for example, melt mixing. Conventional melt mixing devices, such as co-rotating and counter-rotating extruders, single screw extruders, co-kneaders, disk-type transformers and various other types of extrusion equipment can be used. Preferably, extruders, more preferably, twin screw extruders may be used. Extruders designed for this purpose, known to those skilled in the art can be used for melting, mixing, extruding and pelletizing the composition (C). Another object of the present invention is a method of manufacturing a urea reservoir or device used in a urea injection system comprising the step of molding or extruding a composition ( VS).

The molding process generally consists of an injection molding process, the composition (C) being injected into a mold at a temperature above the melting point of the aromatic polyamide (A). Various injection molding techniques can be used. Generally, in all these techniques, the mold will be equipped with multiple injection units. Critical variables such as draft and mold temperature must be considered when using any of these methods. Those skilled in the art will recognize the factors influencing the injection molding ability including the stress relaxation properties of the material and the temperature dependence of the melt viscosity and the exact conditions can be determined by trial and error. when molding small samples. Tubes and hoses are generally manufactured using an extrusion process, the composition (C) being extruded through a die at a temperature above the melting point of the aromatic polyamide (A). Powders, pellets, beads, petals, regrinded material or other forms of the composition (C) may be used, with or without liquid or other additives, premixed or fed separately. The design and size of the urea reservoir or device used in a urea injection system will depend on the particular application envisaged and the specific requirements from the vehicle itself. It has been found that the use of the composition (C) allows the preparation of a urea tank or a device used in a urea injection system which have excellent chemical resistance and excellent thermal resistance which are required in this specific application. Blend The following commercially available materials are used: Fiberglass: OCV® 983 glass fiber from Owens Corning Polyphthalamide AMODEL® 6T / 6I: AMODEL® A-1007 commercially available from SOLVAY SPECIALTY POLYMERS. Polyphthalamide AMODEL® 6T / 6I / 66: AMODEL® A-1004 commercially available from SOLVAY SPECIALTY POLYMERS. Polyphthalamide PA 10T: Vicnyl 700, commercially available from Kingfa Sci. and Tech, Co Ltd.

LLDPE: LLDPE GRSN-9820 NT 7 commercially available from DOW. Polymist® F5A PTFE: Polytetrafluoroethylene powder commercially available from Solvay Specialty Polymers. Magnesium stearate commercially available from Norac, Inc. Impact modifier 1: FUSABOND® E-226 impact modifier commercially available from DuPont. Impact modifier 2: impact modifier ROYALTUF® 498 commercially available from Chemtura.

In addition, two different 6T / 6I polyamides are prepared according to the methods detailed below: The acid-rich polyphthalamide 6T / 6I (70/30) was obtained as follows: A batch stirred vessel is loaded with the ingredients herein. below in the following quantities: 31.2% by weight of hexamethylenediamine, 28.6% by weight of terephthalic acid, 12.3% by weight of isophthalic acid, 0.84% of acetic acid, 0.082% by weight of sodium hypophosphite and 27% by weight of distilled water. A salt solution is obtained by heating the mixture described above to 145 ° C. The contents are pumped continuously into a reactor zone maintained at about 180 psig and 216 ° C and then maintained at about 298 ° C and 1800 psig and then through a 100 psig tubular reactor and heated on a hot water bath. oil at 349 ° C and in a ZSK-30® ventilated twin-screw extruder from Werner and Pfleiderer Corporation equipped with a forward vacuum vent. The temperature of the die is set at 336 ° C. The finished polymer was extruded through a strand die into a water bath at an output rate of about 5.5-6.5 kg / h and then cut into pellets. The melting temperature of the polyamide obtained as measured by DSC was 319 ° C. The polyphthalamide 6T / 61 (70/30) rich in amines is produced according to the process described above but with the aid of the ingredients in the following quantities: 31.5% by weight of hexamethylenediamine, 28.4% by weight of terephthalic acid, 12.2% by weight of isophthalic acid, 0.83% of acetic acid, 0.082% by weight of sodium hypophosphite and 27% by weight of distilled water. The resin produced shows a melting temperature of 319 ° C. General Process for the Preparation of the Compositions The polyamide resins described above are fed to the first cylinder of a ZSK-26 twin-screw extruder comprising 12 zones via a weight loss feeder. The cylinder settings were in the range of 280-330 ° C and the resins were melted prior to zone 5. The other ingredients were fed to zone 5 through a side feed hatch via a control device. diet with weight loss. The speed of the screw was 250 rpm. The extruded products were cooled and pelletized using conventional equipment. The results are summarized in Table 1, indicating each of the resins used and the amount of each ingredient given in percent by weight. Table 1: List of Ingredients of Prepared Compositions El E2 E3 E4 E5 E6 E7 GLASS FIBER 34.5 34.5 34.5 34.5 34.5 PA 10T 65 PA 6T / 61/66 65/25 / 10 65 74.65 84.18 PA 6T / 6I 70/30 65 PA 6T / 6I (70/30) rich in acid 65 PA 6T / 6I (70/30) rich in amine 65 LLDPE 0.5 0.97 0 0.5 0.5 0.5 PTFE 0.25 0.25 Magnesium stearate 0.1 Impact modifier 1 14.6 Impact modifier 2 25 VI of the base resin (dl g) 1.14 0.92 0.92 / 0.96 0.92 0.85 amine end groups (p.eq / g) 94 105.5 105.5 / 35.6 58.6 acid end groups (p.eq / g) 14.8 50 50 / 81.5 52.6 9.1 Tests Glass-filled polyphthalamide samples with various viscosities and stoichiometries are evaluated on the mechanical properties before and after conditioning in the fluid. ADBLUE® Diesel Exhaust (FED) - an aqueous solution of 32.5% high purity urea and 67.5% deionized water - commercially available or in water, both at 80 ° C for 42 days. The aggressive basic conditions are intended to mimic the conditions to which the materials could be exposed during the lifetime of the urea reservoir made from these polyamide compositions. The tensile strength and elongation at break in tension are measured according to ISO 527-2 and the Charpy impact strength on untagged specimen is measured according to ISO 179 before and after the various treatments.

The inherent viscosity (VI) of the base resins is measured according to ASTM D-5225. - 21 - Results Table 2: Mechanical properties results Mechanical properties El unit E2 E3 E4 E5 E6 E7 1. Intial Tensile strength Mpa 226 62 87 20 212 193 210 3 Tensile elongation% 2.5 5,76 5.70 2.8 2.05 1.73 1.97 1 complete failure Charpy impact on untagged specimen kJ / m2 71 pitch of 83 57 49 52 rupture rupture 2. after 42 days of conditioning at 80 ° C. in FED ADBLUE® Tensile strength Mpa 162 50 69 12 137 136 135 0 Tensile elongation% 1.9 3,77 4,17 1,3 1,36 '1,26 1,25 6 6 Rupture complete with Charpy impact on uncut test piece kJ / m2 48, / / 25 25.8 23.1 23.6 1 3. After 42 days conditioning at 80 ° C in water Tensile strength Mpa 150 47 64 11 140 135 123 7 Elongation at break by tensile% 2,5 4,54 4,49 1,2 1,47 '1,42 1,19 6 4 Complete fracture with Charpy impact on uncut test piece kJ / m2 60, / / 23 25.0 24.1 21.5 O As we can see from the results presented in Table 2, compositions El, E2 and E3 retain their mechanical properties after long-term conditioning in ADBLUE® FED. These compositions are therefore candidates of choice for the manufacture of urea reservoirs and other objects used in urea injection systems. With 34.5% by weight of fiberglass in the composition, El achieves the highest mechanical properties in terms of strength and impact resistance. It can also be used for the manufacture of urea tanks where these properties are required. On the other hand, the modified impact resistance compositions E2 and E3 - free from any reinforcing filler - achieve a very high tensile break elongation, making them ideal candidates for flexible transport used for transporting urea from the urea container to the exhaust gas exhaust pipe. Moreover, the data summarized in Table 2 clearly demonstrate the importance of both the nature of terminal chains and viscosity.

Claims (6)

REVENDICATIONS1. A urea reservoir for a carrier vehicle made of a polymer composition (C) comprising an aromatic polyamide (A), the aromatic polyamide (A) having an amine terminal number equal to or greater than the number of carboxyl end groups and the aromatic polyamide (A) having an inherent viscosity of at least 0.90 dl / g as measured by ASTM D-5225. Urea reservoir according to claim 1, wherein the number of amine terminal groups is at least 70 kteq / g. Urea reservoir according to any one of the preceding claims, wherein the number of amine terminal groups is at least 90% by g / g. Urea reservoir according to any one of the preceding claims, the aromatic polyamide (A) being a polyphthalamide. Urea reservoir according to claim 4, the polyphthalamide being a PA6T / 6I / 66. A urea reservoir according to any one of the preceding claims, wherein the polymer composition (C) comprises, in addition to the aromatic polyamide (A), at least 20% by weight of a reinforcing filler, based on the weight total of the composition (C), preferably glass fibers.