Polyamide composition and tubular or pipe multilayer structure containing same

Abstract

The present invention relates to polyamide compositions and tubular or pipe multilayer structures comprising same.

Description

[Technical Field]

[0001] The present invention relates to a polyamide composition and a tubular or pipe multilayer structure containing the same. [Background technology]

[0002] Environmental stress cracking (ESC) is the formation of cracks in materials caused by relatively low tensile stress and environmental conditions. Environmental stress crack resistance (ESCR) is a crucial property required in plastics to extend their lifespan. It is one of the most common causes of unexpected brittle fracture in polymers, especially thermoplastics.

[0003] In particular, tubes or pipes that carry liquid fluids, such as alcohol and liquid fuels, require improved barrier properties against these fluids, as well as good flexibility and resistance to environmental conditions.

[0004] Compositions containing polyhexamethylene adipamide (PA 66) or polycaprolactam (PA 6) are known to be unsuitable for the manufacture of tubes or pipes. This is because these polymers do not exhibit resistance to saline solutions such as zinc chloride (ZnCl2) solution. Such resistance is required by automotive manufacturers and is defined by international standards such as SAE J844 for air brake tubes. Simply put, this test consists of applying bending force to determine the material's resistance to cracking or splitting when immersed in saline solution, particularly ZnCl2. Therefore, a pipe made of PA 66 or PA 6, immersed in a ZnCl2 solution and subjected to mechanical stress, will crack and even burst within minutes.

[0005] To overcome this problem, preparations have been made to use polyamides derived from monomers with a larger number of carbon atoms, i.e., 11 or 12. These polyamides exhibit improved resistance to ZnCl2 testing, but have limited impact strength at ambient temperatures and are expensive to manufacture.

[0006] Polyamide compositions for hot-melt adhesives are described in US2003 / 0232962(A1). The polyamide compositions described herein comprise the reaction product of a dimeric acid (e.g., a dimeric acid containing at least 98% by weight of dimers), caprolactam, hexamethylenediamine, sebacic acid, and an optional chain arrestor.

[0007] U.S. Patent No. 5,256,460(A) describes a thermoplastic composition comprising a mixture of a thermoplastic copolymer and a polyolefin containing grafted functional groups. The thermoplastic copolymer was obtained by copolymerizing ε-caprolactam with an amino acid monomer or lactam thereof containing at least nine carbon atoms, or by copolymerizing a mixture of hexamethylenediamine and a dicarboxylic acid monomer containing at least nine carbon atoms.

[0008] U.S. Patent No. 6,060,562(A) describes another thermoplastic composition comprising a matrix made of a thermoplastic polymer and at least one compound that improves the resilience of the thermoplastic composition. The matrix comprises a mixture of a first thermoplastic resin comprising a copolymer of ε-caprolactam and at least one of an amino acid having at least nine carbon atoms, or a lactam corresponding to an amino acid having at least nine carbon atoms, or a mixture of hexamethylenediamine and a diacid having at least nine carbon atoms, wherein the ratio of weight% of ε-caprolactam to weight% of the mixture of hexamethylenediamine and diacid is 4 to 9; and a second thermoplastic resin comprising a monomeric polyamide or copolyamide having fewer than nine carbon atoms, wherein the content of the second thermoplastic resin in the matrix is ​​40 to 80% by weight of the matrix and more than 20% by weight of the total composition.

[0009] Another U.S. Patent No. 8,153,215(B1) discloses a multilayer structure comprising two superimposed layers, namely an inner layer and an outer layer. The inner layer comprises a thermoplastic polyamide and an agent that modifies the impact resistance by a weight ratio of 10 to 50%, while the outer layer is based on a polyamide composition comprising, as a polymer matrix, a thermoplastic copolymer obtained by copolymerization of ε-caprolactam with at least one monomer selected from amino acids or corresponding lactams containing at least nine carbon atoms, and a mixture of hexamethylenediamine and diacids containing at least nine carbon atoms, wherein the weight ratio of ε-caprolactam to hexamethylenediamine and diacids and / or amino acids is 4 to 9, or a mixture of at least such thermoplastic polyamide or copolyamide obtained by polymerization of monomers containing fewer than nine carbon atoms.

[0010] Despite the above, existing polyamide compositions and the tubes or pipes obtained therefrom cannot provide acceptable ZnCl2 resistance according to SAE J844. In many cases, existing tubes or pipes compromise on mechanical properties such as flexural modulus, tensile modulus, and elongation at break when meeting the requirements of SAE J844, though not limited to these. Therefore, they are unsuitable for applications such as air brake tubes, air conditioning pipes, pneumatic pipes, and fuel pipes. Furthermore, existing compositions also lead to delamination in multilayer tube or pipe structures due to insufficient adhesion between them. This shortens the lifespan of the tube or pipe structure. In addition, the presence of long-chain polyamides in these compositions increases the overall cost of the resulting tubes or pipes, or creates supply problems due to their unavailability.

[0011] Therefore, the object of the present invention was to provide a polyamide composition and a tubular or pipe multilayer structure comprising the polyamide composition that can satisfy the requirements of stress crack resistance measured in a ZnCl2 solution according to SAE J844 for 200 hours and have acceptable mechanical properties such as, but not limited to, flexural modulus, tensile modulus, and elongation at fracture without delamination, thereby being suitable for manufacturing inexpensive air brake tubes, air conditioning tubes, pneumatic tubes, and fuel tubes. [Overview of the Initiative]

[0012] Surprisingly, we found that the above objective is achieved by providing a polyamide composition comprising a polyamide copolymer obtained by reacting (i) ε-caprolactam with (ii) a mixture of hexamethylenediamine and a diacid containing at least nine carbon atoms, wherein the weight ratio between (i) and (ii) is 1.0:1.0 to 3.0:1.0 as described below.

[0013] Therefore, in one aspect, the invention of this claim is: (a) (i) ε-Caprolactam and, (ii) a mixture of hexamethylenediamine and a diacid containing at least 9 carbon atoms, are reacted to obtain a polyamide copolymer, where the weight ratio between (i) and (ii) is 1.0:1.0 to 3.0:1.0, a polyamide copolymer, (b) at least one polyamide different from (a), (c) at least one impact modifier, (d) an additive, and relates to a polyamide composition.

[0014] In another aspect, the invention according to this claim relates to a process for preparing the above polyamide composition by mixing the polyamide copolymer (a), the polyamide (b), the impact modifier (c), and the additive (d).

[0015] In yet another aspect, the invention according to this claim relates to a molded article containing the above polyamide composition.

[0016] In still another aspect, the invention according to this claim relates to the use of the above polyamide composition for a molded article.

[0017] In a further aspect, the invention according to this claim relates to a tubular or pipe multilayer structure comprising an innermost layer, an intermediate layer, and an outermost layer, wherein the innermost layer and the outermost layer are, independently of each other, (a) (i) ε-Caprolactam and, (ii) a mixture of hexamethylenediamine and a diacid containing at least 9 carbon atoms, are reacted to obtain a polyamide copolymer, where the weight ratio between (i) and (ii) is 1.0:1.0 to 3.0:1.0, and contains a polyamide copolymer, The intermediate layer (b) contains at least one polyamide different from (a), and At least one impact modifier (c) and additive (d) are present in at least one of the innermost layer, the intermediate layer, and the outermost layer. [Modes for carrying out the invention]

[0018] Before describing the compositions and formulations of the present invention, it should be understood that the present invention is not limited to the specific compositions and formulations described, as such compositions and formulations can naturally vary. It should also be understood that the technical terms used herein are not intended to limit the scope of the present invention, as it is limited only by the appended claims.

[0019] As used herein, the terms “comprising,” “comprises,” and “comprised of” are synonymous with “including,” “includes,” or “containing,” and are comprehensive or open-ended and do not exclude additional, unlisted members, elements, or process steps. As used herein, the terms “comprising,” “comprises,” and “comprised of” will be understood to include the terms “consisting of,” “consists,” and “consists of.”

[0020] Furthermore, terms such as “first,” “second,” “third,” or “a,” “b,” “c,” “d,” and similar terms in the description and claims are used to distinguish between similar elements and do not necessarily describe a sequential or chronological order. It should be understood that such terms are interchangeable under appropriate circumstances, and that embodiments of the invention described herein may be implemented in any order other than those described or illustrated herein. In the case of terms such as “first,” “second,” “third,” or “(A),” “(B),” and “(C),” or “(a),” “(b),” “(c),” “(d),” “i,” “ii,” relating to a method or a step in use or analysis, there may be no consistency in time or time intervals between steps; that is, the steps may be performed simultaneously, or, unless otherwise stated in the application as described above or below herein, there may be time intervals of seconds, minutes, hours, days, weeks, months, or years between such steps.

[0021] The following sections define various aspects of the present invention in more detail. Each aspect thus defined may be combined with any other aspect or more of the invention unless otherwise explicitly stated to the contrary. In particular, any feature indicated as preferred or advantageous may be combined with any other feature or more of the invention indicated as preferred or advantageous.

[0022] Throughout this specification, any reference to “one embodiment” or “an embodiment” means that a particular feature, structure, or characteristic described in relation to an embodiment is included in at least one embodiment of the present invention. Therefore, the appearance of the phrase “a certain embodiment” or “one embodiment” in various places throughout this specification does not necessarily all refer to the same embodiment, although it may. Furthermore, in one or more embodiments, certain features, structures, or characteristics may be combined in any preferred manner, as will be apparent to those skilled in the art from this disclosure. Furthermore, some embodiments described herein include some features included in other embodiments, but not others, and combinations of features from different embodiments mean that, as those skilled in the art will understand, they form different embodiments within the scope of the present invention. For example, in the appended claims, any of the claimed embodiments may be used in any combination.

[0023] Furthermore, the range defined throughout the specification includes the final value; that is, the range 1 to 10 means that both 1 and 10 are included in the range. To avoid misunderstanding, the applicant shall have rights to any equivalent in accordance with applicable law.

[0024] Furthermore, throughout the explanation, the phrases "ZnCl2 resistance" and "ESCR resistance" refer to stress crack resistance measured in a ZnCl2 solution over a 200-hour period according to SAE J844.

[0025] One aspect of the present invention is, (a) (i) ε-caprolactam and, (ii) A polyamide copolymer obtained by reacting a mixture of hexamethylenediamine and a diacid containing at least nine carbon atoms, A polyamide copolymer in which the weight ratio between (i) and (ii) is 1.0:1.0 to 3.0:1.0, (b) At least one polyamide different from (a), (c) At least one impact modifier, (d) An additive, and relates to Embodiment 1 of a polyamide composition.

[0026] The composition of the present invention according to Embodiment 1 exhibits acceptable ZnCl2 resistance and, among others, mechanical properties such as flexural modulus, tensile modulus, and elongation at break.

[0027] Polyamide copolymer (a) In one embodiment, the diacid contains 9 to 40 carbon atoms in Embodiment 1. In this context, diacids containing 9 to 40 carbon atoms include saturated or unsaturated aliphatic and / or aromatic compounds having 7 to 38 carbon atoms and two carboxy groups (-COOH groups). Thus, the diacid containing 9 to 40 carbon atoms can be branched or unbranched or alicyclic. For example, the diacid can be selected from azelaic acid, sebacic acid, undecanedioic acid, dodecanedioic acid, tridecanedioic acid, tetradecanedioic acid, and hexadecanedioic acid.

[0028] In another embodiment, the diacid contains 32 to 40 carbon atoms in Embodiment 1. In this context, diacids containing 32 to 40 carbon atoms can also be referred to as "C 32 ~C 40 diacid" or "C 32 ~C 40 diacid" or "C 32 ~C 40 dimer fatty acid". C 32 ~C 40 Dimer acids are known to those skilled in the art and are usually prepared by dimerization of unsaturated fatty acids. This dimerization can be catalyzed, for example, by clay. Suitable unsaturated fatty acids for obtaining C 32 ~C 40 dimer acids include, for example, unsaturated C 16 fatty acid, unsaturated C 18 fatty acid, and unsaturated C 20 fatty acid.

[0029] In yet another embodiment, the diacid of Embodiment 1 containing 32 to 40 carbon atoms is unsaturated C 16 fatty acids, unsaturated C 18 fatty acids, and unsaturated C 20 From the group consisting of fatty acids, unsaturated fatty acids are selected, and particularly preferably unsaturated C 18 It is prepared from fatty acids.

[0030] In one embodiment, a suitable unsaturated C 16 The fatty acid is palmitoleic acid ((9Z)-hexadeca-9-enoic acid).

[0031] In one embodiment, a suitable unsaturated C 20 The fatty acids are selected from gadoleic acid ((9Z)-eicosa-9-enoic acid), eicosenoic acid ((11Z)-eicosa-11-enoic acid), arachidonic acid ((5Z,8Z,11Z,14Z)-eicosa-5,8,11,14-tetraenoic acid), and thymnodonic acid ((5Z,8Z,11Z,14Z,17Z)-eicosa-5,8,11,14,17-pentaenoic acid).

[0032] In another embodiment, the diacid in Embodiment 1 contains 36 carbon atoms. In particular, the diacid in Embodiment 1 contains C 36 Contains dimeric acids. C 36 Dimeric acids are unsaturated C 18 It is prepared starting from fatty acids. Such unsaturated C 18The fatty acids are petrosillanic acid ((6Z)-octadecenoic acid), oleic acid ((9Z)-octadec-9-enoic acid), elaidic acid ((E)-octadec-9-enoic acid), vaccenic acid ((11E)-octadec-11-enoic acid), linoleic acid ((9Z,12Z)-octadec-9,12-dienoic acid), alpha-linolenic acid ((9Z,12Z,15Z)-octadec-9,12,15-trienoic acid), and gamma-linolenic acid ((6Z,9Z,12Z)- Selected from octadeca-6,9,12-trienoic acid, calendic acid ((8E,10E,12Z)-octadeca-8,10,12-trienoic acid), punic acid (9Z,11E,13Z-octadeca-9,11,13-trienoic acid), α-eleostearic acid ((9Z,11E,13E)-octadeca-9,11,13-trienoic acid), and β-eleostearic acid ((9E,11E,13E)-octadeca-9,11,13-trienoic acid).

[0033] In one embodiment, the preparation of diacids from unsaturated fatty acids and trimer acids can be further formed, and unreacted residues of unsaturated fatty acids may remain. The formation of trimer acids is known to those skilled in the art.

[0034] In one embodiment, unsaturated C 18 The fatty acids are selected from petrosillanic acid ((6Z)-octadecenoic acid), oleic acid ((9Z)-octadec-9-enoic acid), elaidic acid ((E)-octadec-9-enoic acid), vaccenic acid ((11E)-octadec-11-enoic acid), and linoleic acid ((9Z,12Z)-octadec-9,12-dienoic acid).

[0035] In another embodiment, the diacid in Embodiment 1 refers to a mixture prepared by oligomerization of unsaturated fatty acids. These are prepared, for example, by catalytic dimerization of unsaturated fatty acids from plant sources, in which case the starting material used is particularly unsaturated C 16 ~C 20The addition is primarily of the Diels-Alder type, and the result is a mixture of mainly dimeric products, which are alicyclic, linear aliphatic, branched aliphatic, and also have C6-aromatic hydrocarbon groups between the carboxyl groups, depending on the number and position of double bonds in the fatty acid used for the preparation of the dimeric acid. Depending on the mechanism and / or subsequent hydrogenation, the aliphatic radical can be saturated or unsaturated, and the proportion of aromatic groups can also vary. In that case, the radical between the carboxylic acid groups contains, for example, 32 to 40 carbon atoms. It is preferable to use a fatty acid with 18 carbon atoms for preparation so that the dimeric product has 36 carbon atoms. In one embodiment, the radical connecting the carboxyl groups of the diacid does not have an unsaturated bond or an aromatic hydrocarbyl radical.

[0036] In one embodiment, C is selected from linolenic acid, linoleic acid, and / or oleic acid. 18 The diacid in Embodiment 1 is prepared using a fatty acid.

[0037] In one embodiment, depending on the reaction regime, the above oligomerization yields a mixture containing not only dimeric molecules but also trimer molecules, monomer molecules, and other by-products. Purification is typically performed by distillation. Commercially available dimeric acids generally contain at least 80% by weight of dimeric molecules, up to 19% by weight of trimer molecules, and 1% by weight or less of monomer molecules, as well as other by-products.

[0038] In one embodiment, the dimeric acid consists of at least 90% by weight, preferably at least 95% by weight, and more preferably at least 98% by weight of dimeric fatty acid molecules. The proportions of monomer, dimer, and trimer molecules, as well as other by-products, in the dimeric acid can be determined, for example, by gas chromatography (GC). Here, the dimeric acid is converted to the corresponding methyl ester via the boron trifluoride method (see DIN EN ISO 5509) before GC analysis and then analyzed by GC.

[0039] In one embodiment, the preparation of the diacid in Embodiment 1 involves oligomerization of an unsaturated fatty acid. This oligomerization primarily produces a dimer product in a quantity of at least 80% by weight, or about 90% by weight, or 95% by weight, or about 98% by weight. Thus, the fact that oligomerization overwhelmingly produces a dimer product containing exactly two fatty acid molecules justifies the name oligomerization, which is used in any case as it is commonly used.

[0040] In another embodiment, dimeric acids are also available as commercial products. Examples of these include Oleon's Radiacid®, Croda's Pripol®, BASF SE's Empol®, and Arizona Chemical's Unidyme®.

[0041] In another embodiment, polyamide copolymer (a) is obtained by reacting (i) ε-caprolactam with (ii) a mixture of hexamethylenediamine and a diacid containing 36 carbon atoms, with a weight ratio of (i) to (ii) being 1:1 to 3:1.

[0042] In one embodiment, the weight ratio between (i) and (ii) in Embodiment 1 described herein is 1.1:1.0 to 3.0:1.0, or 1.2:1.0 to 3.0:1.0, or 1.3:1.0 to 3.0:1.0, or 1.4:1.0 to 3.0:1.0, or 1.5:1.0 to 3.0:1.0. In other embodiments, the weight ratio is 1.6:1.0 to 3.0:1.0, or 1.7:1.0 to 3.0:1.0, or 1.8:1.0 to 3.0:1.0, or 1.9:1.0 to 3.0:1.0, or 2.0:1.0 to 3.0:1.0. In another embodiment, the weight ratio is 2.0:1.0 to 2.9:1.0, or 2.0:1.0 to 2.8:1.0, or 2.0:1.0 to 2.7:1.0, or 2.0:1.0 to 2.6:1.0, or 2.0:1.0 to 2.5:1.0. In yet another embodiment, the weight ratio is 2.1:1.0 to 2.5:1.0, or 2.2:1.0 to 2.5:1.0, or 2.2:1.0 to 2.4:1.0. In yet another embodiment, the weight ratio is 2.25:1.0 to 2.4:1.0, or 2.25:1.0 to 2.35:1.0.

[0043] In further embodiments, the weight ratio between (i) and (ii) in Embodiment 1 described herein is 2.3:1.0. The ratio of 2.3:1.0 corresponds to 30% by weight of (ii) and 70% by weight of (i) in Embodiment 1 described herein.

[0044] In one embodiment, the reaction between (i) and (ii) in Embodiment 1 is carried out at a temperature of 250°C to 350°C. The reaction can be carried out using a suitable mixing method known to those skilled in the art. The polyamide copolymer (a) thus obtained has a viscosity number between 150 and 350 mL / g. The viscosity number is determined from a 0.5 wt% solution of polyamide copolymer (a) in 96 wt% sulfuric acid at 25°C according to ISO 307.

[0045] The amount of polyamide copolymer (a) described herein is 40% to 90% by weight, based on the total weight of the polyamide composition described herein.

[0046] Polyamide (b) In one embodiment, polyamide (b) is different from polyamide copolymer (a). In other embodiments, polyamide (b) in Embodiment 1 has a viscosity number of 90 mL / g to 350 mL / g. In this context, the viscosity number is determined from a 0.5 wt% solution of polyamide (b) in 96 wt% sulfuric acid at 25°C, according to ISO 307.

[0047] A preferred polyamide (b) in Embodiment 1 is, for example, derived from a lactam having 7 to 13 ring members, or obtained by the reaction of a dicarboxylic acid with a diamine. Examples of polyamides derived from lactams include polycaprolactam, polycapryloractam, and / or polylaurolactam.

[0048] In other embodiments, suitable polyamides include, but are not limited to, those obtained from ω-aminoalkyl nitriles, such as aminocapronitrile, which yields nylon-6. In addition, dinitriles can react with diamines. For example, adiponitrile can react with hexamethylenediamine to obtain nylon-6,6. Nitrile polymerization is carried out in the presence of water and is also known as direct polymerization.

[0049] When polyamides obtained from dicarboxylic acids and diamines are used, dicarboxylalkanes (aliphatic dicarboxylic acids) having 6 to 36 carbon atoms, 6 to 12 carbon atoms, or 6 to 10 carbon atoms may be used. Aromatic dicarboxylic acids are also preferred. Examples of dicarboxylic acids include adipic acid, azelaic acid, sebacic acid, dodecanediic acid, and terephthalic acid and / or isophthalic acid.

[0050] Suitable diamines include, for example, alkanediamines having 4 to 36 carbon atoms, or 6 to 12 carbon atoms, particularly 6 to 8 carbon atoms, and aromatic diamines, such as m-xylylenediamine, di(4-aminophenyl)methane, di(4-aminocyclohexyl)methane, 2,2-di(4-aminophenyl)propane, 2,2-di(4-aminocyclohexyl)propane, and 1,5-diamino-2-methylpentane.

[0051] In other embodiments, the polyamide (b) in Embodiment 1 includes polyhexamethylene dipamide, polyhexamethylene sebakamid, and polycaprolactam, and also, in particular, nylon-6 / 6,6 having a caprolactam unit proportion of 5% to 95% by weight.

[0052] The following non-exclusive list includes the aforementioned polyamide(b) in Embodiment 1. [Table 1] [Table 2]

[0053] In one embodiment, the polyamide (b) in Embodiment 1 is selected from PA6, PA11, PA12, PA6.6, PA6.9, PA6.10, PA6.12, and mixtures thereof.

[0054] In other embodiments, the polyamide (b) in Embodiment 1 is selected from PA6, PA12, PA6.6, PA6.10, and PA6.12.

[0055] In yet another embodiment, the polyamide (b) in Embodiment 1 is selected from PA12, PA6.6, PA6.10, and PA6.12.

[0056] In another embodiment, polyamide(b) in Embodiment 1 is a mixture of polyamides described herein.

[0057] In another embodiment, the polyamide (b) in Embodiment 1 further comprises a reinforcing agent. Suitable reinforcing agents are selected from metal fibers, metallized inorganic fibers, metallized synthetic fibers, glass fibers, polyester fibers, polyamide fibers, polyvinyl alcohol fibers, aramid fibers, graphite fibers, carbon fibers, ceramic fibers, mineral fibers, basalt fibers, inorganic fibers, aramid fibers, kenaf fibers, jute fibers, flax fibers, hemp fibers, cellulose fibers, sisal fibers, and coir fibers.

[0058] For the purposes of the present invention, the reinforcing agent can be obtained in any shape and size. Furthermore, the reinforcing agent can be subjected to a suitable surface treatment agent or sizing. For example, the reinforcing agent can be surface-treated using a coupling agent, for example, but not limited to urethane coupling agents and epoxy coupling agents. For this purpose, any suitable surface treatment technique can be used. For example, any suitable coating process can be used, such as but not limited to dip coating and spray coating.

[0059] In one embodiment, the urethane coupling agent comprises at least one urethane group. Urethane coupling agents suitable for use with reinforcing agents are known to those skilled in the art and are described, for example, in U.S. Patent Application Publication No. 2018 / 0282496. In one embodiment, the urethane coupling agent comprises a reaction product of an isocyanate, such as, for example, m-xylylene diisocyanate (XDI), 4,4'-methylenebis(cyclohexyl isocyanate) (HMDI), or isophorone diisocyanate (IPDI), and a polyester polyol or polyether polyol.

[0060] In other embodiments, the epoxy coupling agent comprises at least one epoxy group. Epoxy coupling agents suitable for use with reinforcing agents are known to those skilled in the art and are described, for example, in U.S. Patent Application Publication 2015 / 0247025, which is incorporated herein by reference. In one embodiment, the epoxy coupling agent is selected from aliphatic epoxy coupling agents, aromatic epoxy coupling agents, or mixtures thereof. Non-limiting examples of aliphatic coupling agents include polyether polyepoxy compounds having two or more epoxy groups in the molecule, and / or polyol polyepoxy compounds having two or more epoxy groups in the molecule. Bisphenol A epoxy compounds or bisphenol F epoxy compounds may be used as aromatic coupling agents.

[0061] The preferred amounts of these coupling agents described herein are well known to those skilled in the art. However, in one embodiment, the coupling agent may be present in an amount of 0.1 to 10.0 parts by mass per 100 parts by mass of the reinforcing agent.

[0062] The amount of polyamide(b) in Embodiment 1 described herein is 1.0% to 50% by weight, based on the total weight of the polyamide composition. In one embodiment, the amount is 1.0% to 48% by weight, or 1.5% to 48% by weight, or 1.5% to 46% by weight, or 2.0% to 46% by weight, or 2.0% to 44% by weight. In other embodiments, the amount is 2.5% to 44% by weight, or 2.5% to 42% by weight, or 3.0% to 42% by weight, or 3.5% to 42% by weight, or 4.0% to 42% by weight. In yet another embodiment, the amount is 4.0% to 40% by weight, or 4.5% to 40% by weight, or 5.0% to 40% by weight.

[0063] Impact modifier (c) Impact modifiers for use in the present invention, often also referred to as rubber or elastomer polymers, are described, for example, in US2014 / 0323631(A1) and US2008 / 0070023(A1). Impact modifier (c) comprises a functional group that can react with a polyamide. The polar functional group is selected from acid, anhydride, acrylic, methacrylic, or epoxy functional groups. Preferred impact modifiers (c) in Embodiment 1 are selected from (i) ethylene polymers and copolymers grafted with carboxylic acids, their anhydrides, maleimides, or epoxy compounds, and (ii) olefin or acrylic acid or anhydride terpolymers and ionomers.

[0064] In ethylene polymers and copolymers grafted with carboxylic acids, their anhydrides, maleimides, or epoxy compounds, the carboxylic acid or its anhydride is selected from maleic acid, fumaric acid, itaconic acid, acrylic acid, crotonic acid, C1-C4 alkyl half-esters of maleic acid, and their anhydrides or derivatives, including maleic anhydride. Olefin rubbers can also be used as suitable impact modifiers (c).

[0065] In one embodiment, the impact modifier (c) is an ethylene copolymer grafted with a carboxylic acid or any anhydride, for example, an ethylene copolymer grafted with maleic anhydride. In other embodiments, the impact modifier (c) may be maleic anhydride-grafted ethylene propylene dienterpolymer (EPDM) (maleic anhydride 2.0% to 6.0% by weight), maleic anhydride-grafted ethylene propylene (maleic anhydride 0.5% to 6% by weight), maleic anhydride-grafted low-density polyethylene (maleic anhydride 0.2% to 6% by weight), and maleic anhydride-grafted ethylene butyl acrylate (maleic anhydride 0.2% to 6% by weight).

[0066] Olefin, acrylic, or anhydride terpolymers and ionomer impact modifiers are polymerized from chain units derived from monomers, including (a) ethylene, butylene, propylene, and combinations thereof; (b) 2% to 25% by weight of an acid selected from acrylic acid, methacrylic acid, and mixtures thereof; and (c) 0.1% to 15% by weight of a dicarboxylic acid monomer selected from maleic acid, fumaric acid, itaconic acid, maleic anhydride, itaconic anhydride, C1-C4 alkyl half-esters of maleic acid, and mixtures of these dicarboxylic acid monomers. In one embodiment, the terpolymer is an ethylene / methacrylic acid / maleic anhydride ionomer (with maleic anhydride at 0.5% to 12% by weight). The ionomer can be formed by neutralizing the carboxylic acid units in the terpolymer using a metal ion selected from zinc, magnesium, manganese, and mixtures thereof, either alone or in combination with sodium or lithium ions. The terpolymer may further contain up to 40% by weight of C1-C8 alkyl acrylate monomer units.

[0067] In Embodiment 1 described herein, the impact modifier (c) is present in an amount of 0.01% to 15% by weight, based on the total weight of the polyamide composition.

[0068] In one embodiment, the amount of impact modifier (c) in Embodiment 1 is 0.01% to 15% by weight, or 0.1% to 15% by weight, 1.0% to 15% by weight, or 2.0% to 15% by weight. In other embodiments, the amount is 2.0% to 14% by weight, 3.0% to 14% by weight, or 4.0% to 14% by weight, or 5.0% to 14% by weight, or 5.0% to 13% by weight. In yet another embodiment, the amount is 6.0% to 13% by weight, or 7.0% to 13% by weight, or 8.0% to 13% by weight, or 8.0% to 12% by weight, or 9.0% to 11% by weight.

[0069] In one embodiment, the impact modifier (c) in Embodiment 1 has a glass transition temperature of less than 0°C or less than -20°C.

[0070] Additives (d) A suitable additive (d) in Embodiment 1 is selected from plasticizers, antioxidants, stabilizers, nucleating agents, dyes, pigments, flame retardants, lubricants, UV absorbers, antistatic agents, fungicides, bactericides, IR absorbers, surfactants, hydrolysis regulators, curing agents, and cell modifiers. A mixture of these additives (d) can also be used to obtain the polyamide composition of Embodiment 1.

[0071] In one embodiment, additive (d) in Embodiment 1 is selected from plasticizers, antioxidants, stabilizers, nucleating agents, dyes, pigments, flame retardants, lubricants, UV absorbers, antistatic agents, fungicides, bactericides, and IR absorbing materials.

[0072] These additives (d) are well known in the prior art and have been described in many applications. Furthermore, preferred amounts of these additives (d) are well known to those skilled in the art. In one embodiment, the amount of additive (d) in Embodiment 1 is 0.01% to 10% by weight, based on the total weight of the polyamide composition.

[0073] In other embodiments, the amount of additive (d) in Embodiment 1 is 0.01% to 15% by weight, or 0.1% to 15% by weight, 1.0% to 15% by weight, or 2.0% to 15% by weight. In other embodiments, the amount is 2.0% to 14% by weight, 3.0% to 14% by weight, or 4.0% to 14% by weight, or 5.0% to 14% by weight, or 5.0% to 13% by weight. In yet another embodiment, the amount is 6.0% to 13% by weight, or 7.0% to 13% by weight, or 8.0% to 13% by weight, or 8.0% to 12% by weight, or 9.0% to 11% by weight.

[0074] process Another aspect of the present invention is Embodiment 2, which relates to a process for preparing the polyamide composition of Embodiment 1 described herein.

[0075] In one embodiment, the mixing of the polyamide copolymer (a), polyamide (b), impact modifier (c), and additive (d) is carried out in Embodiment 2. Suitable techniques for mixing are well known to those skilled in the art. For example, the polyamide composition of Embodiment 1 described herein can be mixed in a molten state in a single-screw or twin-screw extruder. In other embodiments, the components (a), (b), (c), and (d) in Embodiment 2 can be mixed in any order.

[0076] Modeled product Another aspect of the present invention is Embodiment 3, relating to a molded article comprising the polyamide composition of Embodiment 1 or a polyamide composition obtained according to Embodiment 2 as described herein.

[0077] In one embodiment, the molded product in Embodiment 3 can be obtained by molding the polyamide composition of Embodiment 1 or the polyamide composition obtained according to Embodiment 2, as described herein. Suitable molding techniques include, but are not limited to, molding, extrusion molding, and extrusion blow molding.

[0078] In another embodiment, the fabricated part in Embodiment 3 could be, for example, an air brake pipe, an air conditioning pipe, a pneumatic pipe, and a fuel pipe. These examples of fabricated parts are merely illustrative but correspond to components requiring good ZnCl2 resistance, low fuel permeability, fuel resistance, and high mechanical and flexible properties.

[0079] use Another aspect of the present invention is Embodiment 4, relating to the use of the polyamide composition of Embodiment 1 or a polyamide composition obtained according to Embodiment 2, as described herein, for a molded article. The molded article in Embodiment 4 is the molded article of Embodiment 3 as described herein.

[0080] Tubular or multi-layered pipe structure A further aspect of the present invention is Embodiment 5 relating to a tubular or pipe multilayer structure comprising an innermost layer, an intermediate layer, and an outermost layer, wherein the innermost and outermost layers independently comprise a polyamide copolymer (a), and the intermediate layer comprises a polyamide (b). Impact modifiers (c) and additives (d) are present in at least one of the innermost, intermediate, and outermost layers. The layers of the tubular or pipe multilayer structure in Embodiment 5 consist of a polyamide composition comprising (a), (b), (c), and (d) of Embodiment 1, as described herein.

[0081] In this context, the term “multilayer” refers to the presence of at least three layers in Embodiment 5. In one embodiment, a tubular or pipe multilayer structure may include more than three layers, e.g., four, five, six, or seven layers. Such layers may be referred to as intermediate layers. Some of these intermediate layers are advantageously formed from the same composition as those forming the outermost layer. These layers are referred to as external intermediate layers. Other intermediate layers are formed from the same composition as those forming the innermost layer. Such layers are referred to as internal intermediate layers.

[0082] In one embodiment, the internal and external intermediate layers are arranged alternately in the lateral direction of the tubular or pipe multilayer structure in Embodiment 5.

[0083] Furthermore, without departing from the scope of the present invention, the tubular or pipe multilayer structure in Embodiment 5 may include an intermediate layer made from a composition other than the polyamide composition of Embodiment 1, as described herein.

[0084] Another aspect of the present invention is Embodiment 6 relating to a tubular or pipe multilayer structure comprising an innermost layer, an intermediate layer, and an outermost layer, wherein the innermost and outermost layers independently comprise a polyamide copolymer (a), and the intermediate layer comprises a polyamide (b). Impact modifiers (c) and additives (d) are present in at least one of the innermost, intermediate, and outermost layers. The layers of the tubular or pipe multilayer structure in Embodiment 5 comprise a polyamide composition comprising (a), (b), (c), and (d) of Embodiment 1, as described herein.

[0085] In another embodiment, the tubular or pipe multilayer structure in Embodiment 5 or 6 has an opening at each end. The preferred diameter of the opening depends on the specific use of these tubular or pipe multilayer structures and is therefore well known to those skilled in the art.

[0086] In other embodiments, the innermost layer in Embodiment 5 or 6 is in direct contact with the intermediate layer. In other words, the innermost layer described herein has good adhesion to the intermediate layer described herein. In this context, “good adhesion” means that there is no delamination between layers.

[0087] In yet another embodiment, the intermediate layer in embodiment 5 or 6 is in direct contact with the outermost layer. In other words, the intermediate layer is located between the innermost and outermost layers and has good adhesion to both layers.

[0088] In one embodiment, the thickness of the innermost layer in embodiment 5 or 6 is 0.05 mm to 5.0 mm, or 0.05 mm to 4.5 mm, or 0.06 mm to 4.5 mm, or 0.06 mm to 4.0 mm, or 0.07 mm to 4.0 mm, or 0.07 mm to 3.5 mm. In other embodiments, the thickness is 0.08 mm to 3.5 mm, or 0.08 mm to 3.0 mm, or 0.1 mm to 3.0 mm, or 0.1 mm to 2.0 mm. In other embodiments, the thickness is 0.12 mm to 2.0 mm, 0.12 mm to 1.5 mm, or 0.15 mm to 2.0 mm, or 0.15 mm to 1.5 mm, or 0.15 mm to 1.0 mm. In other embodiments, the thickness is 0.2 mm to 1.0 mm, or 0.2 mm to 0.5 mm.

[0089] In other embodiments, the thickness of the intermediate layer in embodiment 5 or 6 is 1 mm to 20 mm, or 2 mm to 20 mm, or 2 mm to 18 mm, or 5 mm to 18 mm, or 5 mm to 15 mm. In other embodiments, the thickness is 6 mm to 15 mm, or 6 mm to 13 mm, or 7 mm to 13 mm, or 7 mm to 12 mm, or 8 mm to 12 mm.

[0090] In another embodiment, the thickness of the outermost layer in embodiment 5 or 6 is 0.05 mm to 5.0 mm, or 0.05 mm to 4.5 mm, or 0.06 mm to 4.5 mm, or 0.06 mm to 4.0 mm, or 0.07 mm to 4.0 mm, or 0.07 mm to 3.5 mm. In yet another embodiment, the thickness is 0.08 mm to 3.5 mm, or 0.08 mm to 3.0 mm, or 0.1 mm to 3.0 mm, or 0.1 mm to 2.0 mm. In yet another embodiment, the thickness is 0.12 mm to 2.0 mm, 0.12 mm to 1.5 mm, or 0.15 mm to 2.0 mm, or 0.15 mm to 1.5 mm, or 0.15 mm to 1.0 mm. In yet another embodiment, the thickness is 0.2 mm to 1.0 mm, or 0.2 mm to 0.5 mm.

[0091] In yet another embodiment, the tubular or pipe multilayer structure in Embodiment 5 or 6 has a cylindrical or non-cylindrical shape. These shapes are generally produced by using techniques such as co-extrusion of the polyamide composition of Embodiment 1, as described herein, but are not limited thereto. One such technique is described, for example, in European Patent No. 0 436 923(B2).

[0092] Advantageously, the tubular or pipe multilayer structures in Embodiment 5 or 6 exhibit acceptable ZnCl2 resistance over 200 hours and have acceptable mechanical properties such as, but are not limited to, flexural modulus, tensile modulus, and elongation at break without delamination.

[0093] In one embodiment, the tubular or pipe multilayer structure in Embodiment 5 or 6 has a tensile modulus of at least 90 MPa measured at 23°C according to ISO 527-1. In other embodiments, the tensile modulus is 200 MPa to 1200 MPa, or 400 MPa to 1000 MPa, or 600 MPa to 900 MPa.

[0094] In another embodiment, the tubular or pipe multilayer structure in Embodiment 5 or 6 has a load of at least 40 kJ / m³ measured according to ISO 180 / A. 2 It has notched Izod shock resistance at 23°C.

[0095] Considering the above advantages, the tubular or pipe multilayer structures in Embodiment 5 or 6 are suitable for manufacturing inexpensive air brake tubes, air conditioning tubes, pneumatic tubes, and fuel tubes.

[0096] The present invention is illustrated in more detail by the following embodiments and combinations of embodiments arising from the corresponding dependency references and links. I. (a) (i) ε-caprolactam and, (ii) A polyamide copolymer obtained by reacting a mixture of hexamethylenediamine and a diacid containing at least nine carbon atoms, A polyamide copolymer in which the weight ratio between (i) and (ii) is 1.0:1.0 to 3.0:1.0, (b) at least one polyamide different from (a), (c) at least one impact modifier, (d) A polyamide composition comprising an additive. II. The polyamide composition according to Embodiment I, wherein the amount of polyamide copolymer (a) is 40% to 90% by weight, based on the total weight of the polyamide composition. III. A polyamide composition according to Embodiment I or II, wherein the diacid contains 9 to 40 carbon atoms. IV. A polyamide composition according to one or more embodiments I to III, wherein the diacid contains 36 carbon atoms. A polyamide composition according to one or more of Embodiments I to IV, wherein the weight ratio of V.(i) to (ii) is 2.0:1.0 to 3.0:1.0. A polyamide composition according to one or more of Embodiments I to V, wherein the weight ratio of VI.V.(i) to (ii) is 2.0:1.0 to 2.5:1.0. VII. A polyamide composition according to one or more embodiments I to VI, wherein the amount of polyamide(b) is 1.0% to 50% by weight, based on the total weight of the polyamide composition. VIII. A polyamide composition according to one or more embodiments I to VII, wherein the amount of polyamide(b) is 5.0% to 40% by weight, based on the total weight of the polyamide composition. IX. A polyamide composition according to one or more of Embodiments I to VIII, wherein at least one impact modifier is selected from (i) ethylene polymers and copolymers grafted with carboxylic acids, their anhydrides, maleimides, or epoxy compounds, and (ii) terpolymers and ionomers of olefins or acrylic acids or anhydrides. X. A polyamide composition according to one or more embodiments I to IX, wherein the amount of impact modifier (c) is 0.01% to 15% by weight, based on the total weight of the polyamide composition. XI. A polyamide composition according to one or more embodiments I to X, wherein the amount of impact modifier (c) is 7% to 13% by weight, based on the total weight of the polyamide composition. XII. A polyamide composition according to one or more embodiments I to XI, wherein additive (d) is selected from plasticizers, antioxidants, stabilizers, nucleating agents, dyes, pigments, flame retardants, lubricants, UV absorbers, antistatic agents, fungicides, bactericides, and IR absorbing materials. XIII. A polyamide composition according to one or more embodiments I to XII, wherein the amount of additive (d) is 0.01% to 15% by weight, based on the total weight of the polyamide composition. XIV. A process for preparing a polyamide composition according to one or more embodiments I to XIII by mixing a polyamide copolymer (a), a polyamide (b), an impact modifier (c), and an additive (d). XV. A molded article comprising a polyamide composition according to one or more embodiments I to XIII or a polyamide composition obtained by the process according to embodiment 14. XVI. Use of a polyamide composition obtained by one or more embodiments I to XIII or by a process according to embodiment XIV for a molded product. XVII. Use according to Embodiment XVI, in which the molded product is obtained by molding, extrusion, and blow molding. XVIII. A tubular or pipe multilayer structure comprising an innermost layer, an intermediate layer, and an outermost layer, wherein the innermost layer and the outermost layer are independent of each other. (a) (i) ε-caprolactam and, (ii) A polyamide copolymer obtained by reacting a mixture of hexamethylenediamine and a diacid containing at least nine carbon atoms, wherein the weight ratio between (i) and (ii) is 1.0:1.0 to 3.0:1.0, The middle class is, (b) comprising at least one polyamide different from (a), and A tubular or pipe multilayer structure in which at least one impact modifier (c) and additive (d) are present in at least one of the innermost layer, the intermediate layer, and the outermost layer. XIX. The structure according to Embodiment XVIII, wherein the tubular or pipe multilayer structure has an opening at each end thereof. XX. The structure according to Embodiment XVIII or XVIX, wherein the innermost layer is in direct contact with the intermediate layer. XXI. A structure according to one or more embodiments XVIII to XX, wherein the intermediate layer is in direct contact with the outermost layer. A structure according to one or more of Embodiments XVIII to XXI, wherein the weight ratio of XXII.(i) to (ii) is 2.0:1.0 to 3.0:1.0. A structure according to one or more of Embodiments XVIII to XXII, wherein the weight ratio of XXIII.(i) to (ii) is 2.0:1.0 to 2.5:1.0. XXIV. A structure according to one or more of Embodiments XVIII to XXIII, wherein the thickness of the innermost layer is 0.05 mm to 5.0 mm. XXV. A structure according to one or more embodiments XVIII to XXIV, wherein the thickness of the intermediate layer is 1 mm to 20 mm. XXVI. A structure according to one or more embodiments XVIII to XXV, wherein the thickness of the outermost layer is 0.05 mm to 5.0 mm. XXVII. Tensile modulus of at least 90 MPa measured at 23°C according to ISO 527-1 and at least 40 kJ / m² measured according to ISO 180 / A. 2 A structure according to one or more embodiments XVIII to XXVI having notched Izod shock resistance at 23°C. XXVIII. A structure according to one or more embodiments XVIII to XXVII that can satisfy the requirements for stress crack resistance measured in a ZnCl2 solution according to SAE J844 over 200 hours. XXIX. The structure according to one or more embodiments XVIII to XXVIII, wherein the structure is selected from an air brake tube, an air conditioning pipe, and a fuel pipe. [Examples]

[0097] The invention according to this claim is illustrated by the following non-limiting embodiments. [Table 3] [Table 4]

[0098] ZnCl2 resistance The stress crack resistance in ZnCl2 solution was measured using the procedure described in the international standard SAE J844, published in June 1963 and revised on June 12, 1990. This test involved obtaining tubes with an inner diameter of 6 mm and an outer diameter of 8 mm extruded with a specific radius of curvature using the composition under test, and immersing these curved tubes in a cold solution containing 50% by weight of ZnCl2 at 24°C for 200 hours. If no cracks were observed on the outer surface of the tubes when they were removed from the solution, the tubes were considered to have passed the test.

[0099] Polyamide copolymer (PC) ((i):(ii) ratio 2.3:1) Copolyamides of PA 6 and PA 6.36 were prepared by the following method: 932 kg of ε-caprolactam, 323.2 kg of hydrogenated C from Croda 36Dimeric acid, 77.84 kg of 85 wt% hexamethylenediamine aqueous solution, and 153 kg of water were mixed in a 1930 L tank and blanketed with nitrogen. The tank was heated to an external temperature of 290°C, and the mixture was stirred at this temperature for 11 hours. The mixture was stirred under high pressure for the first 7 hours, and under reduced pressure for the next 4 hours, during which time the water formed was removed by distillation. The resulting copolyamide was discharged from the tank, extruded, and pelletized. The resulting copolyamide pellets were extracted with water at 95°C for 4-6 hours, and then dried in a nitrogen stream at 90°C-140°C for 10 hours. The resulting copolyamide had a viscosity number of 259 mL / g, a glass transition temperature of 38°C, and a melting temperature of 188°C. Based on the total weight of the copolyamide, the proportion of polyamide 6.36 in the copolyamide was 30 wt%, and the density was 1.076 g / mL. [Table 5]

[0100] General synthesis of multilayer pipe structures A single-screw extruder was used for the tube extrusion process. For multilayer tubes, two or more extruders were combined to feed the polymer of each layer into the multilayer tube die. The extruded tubes were then drawn into a cooling bath after exiting the die. The bath allowed the tubes to solidify, enabling dimensional control. Once solidified, a cutting machine was used to cut the tubes to the desired length.

[0101] Several three-layer pipe structures were obtained, and their mechanical properties were tested. The results are summarized in Table 2 below. [Table 6]

[0102] As is clear from the above, the multilayer pipe structure according to the present invention does not exhibit any ZnCl2 resistance (200 hours). In fact, compositions with a low amount of polyamide (b), i.e., IE 1, exhibit similar properties to those of IE 2 and IE 3. Furthermore, no delamination is observed in any of the compositions of the present invention.

[0103] A polyamide copolymer (comparative) similar to U.S. Patent No. 6,060,562(A) was prepared as described above, with (i):(ii) ratios of 4.0:1.0 (CE 1) and 9.0:1.0 (CE 2). ZnCl2 resistance (200 hours) was tested for CE 1 and CE 2 as described above. The results are summarized in Table 3 below. [Table 7]

[0104] As is clear from the above, the three-layer pipe structure obtained using IE 1 had ZnCl2 resistance for 200 hours, while those obtained using CE 1 and CE 2 failed the test. Therefore, it is considered that the compositions of the present invention can be used to obtain inexpensive air brake tubes, air conditioning tubes, pneumatic tubes, and fuel tubes that have ZnCl2 resistance (200 hours) and acceptable mechanical properties, as shown above.

Claims

1. A polyamide composition comprising: (a) (i) ε-caprolactam and (ii) a mixture of hexamethylenediamine and a diacid containing at least 9 carbon atoms, a polyamide copolymer obtained by reacting them, wherein the weight ratio between (i) and (ii) is 1.0:1.0 to 3.0:1.0, the polyamide copolymer, (b) at least one polyamide different from (a), (c) at least one impact modifier, (d) an additive, and wherein the impact modifier is selected from (i) an ethylene methacrylic acid copolymer and (ii) an ethylene polymer and copolymer grafted with an epoxy compound, the polyamide composition.

2. The polyamide composition according to claim 1, wherein the diacid contains 9 to 40 carbon atoms.

3. The polyamide composition according to claim 1, wherein the diacid contains 36 carbon atoms.

4. The polyamide composition according to claim 1, wherein the weight ratio between (i) and (ii) is 2.0:1.0 to 3.0:1.

0.

5. The polyamide composition according to claim 1, wherein the additive (d) is selected from a plasticizer, an antioxidant, a stabilizer, a nucleating agent, a dye, a pigment, a flame retardant, a lubricant, a UV absorber, an antistatic agent, an antifungal agent, a bactericide, and an IR absorbing material.

6. A process for preparing the polyamide composition according to any one of claims 1 to 5 by mixing the polyamide copolymer (a), the polyamide (b), the impact modifier (c), and the additive (d).

7. A molded article comprising the polyamide composition according to any one of claims 1 to 5 or the polyamide composition obtained by the process according to claim 6.

8. Use of the polyamide composition according to any one of claims 1 to 5 or the polyamide composition obtained by the process according to claim 6 for a molded article.

9. The use according to claim 8, wherein the molded article is obtained by molding, extrusion molding, and blow molding.

10. A tubular or pipe multilayer structure comprising an innermost layer, an intermediate layer, and an outermost layer, wherein the innermost layer, the intermediate layer, and the outermost layer are each independently (a) (i) ε-caprolactam and (ii) a mixture of hexamethylenediamine and a diacid containing at least 9 carbon atoms, A polyamide copolymer obtained by reacting (i) and (ii) with a weight ratio between (i) and (ii) of 1.0:1.0 to 3.0:1.0, and a polyamide copolymer, (b) at least one polyamide different from (a), (c) at least one impact modifier, (d) an additive, A tubular or pipe multilayer structure comprising.

11. The structure according to claim 10, wherein the tubular or pipe multilayer structure has openings at each of its ends.

12. A tensile modulus of at least 90 MPa measured according to ISO 527-1 at 23°C and a notched Izod impact resistance of at least 40 kJ / m measured according to ISO 180 / A at 23°C ２ The structure according to claim 10 or 11, having a notched Izod impact resistance at 23°C of

13. The structure according to claim 10 or 11, which can meet the requirements of stress corrosion cracking resistance measured in a ZnCl solution according to SAE J844 over 200 hours ２ solution.

14. The structure according to claim 10 or 11, wherein the structure is selected from an air brake tube, an air conditioning pipe, and a fuel pipe.

15. The structure according to any one of claims 10 to 14, wherein the at least one impact modifier is selected from (i) ethylene polymers and copolymers grafted with carboxylic acids, their anhydrides, maleimides, or epoxy compounds, and (ii) terpolymers and ionomers of olefins or acrylic acids or anhydrides.