CZ9903735A3 - Polyamide composition for preparing products by blowing and products obtained from this composition - Google Patents

Abstract

The composition comprises a thermoplastic polymeric a polyamide thermoplastic matrix and at least one an impact-modifying agent present at a concentration of 10 to 50% by weight of the composition; the modulus of elasticity of the composition is less than 1500 MPa. Product in the form of a tube, made by a gradual technique by injection, extrusion or compression comprising 3 the adjacent parts, the other part also obtained by blowing a non-flexible polyamide composition a a central third portion (3) having expanded mold in the mold a bellows made by blowing a polyamide composition.

Description

The present invention relates to a thermoplastic composition having characteristics suitable for use in blow molding processes for components or articles.

In particular, the invention relates to a polyamide-based thermoplastic composition having a low modulus of elasticity and thus allowing the preparation of components or articles that are flexible or which comprise at least one flexible portion.

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Polyamide-based compositions have long been used as raw materials for the manufacture of components or articles which are molded by various molding techniques. Such techniques include, for example, a blow molding process allowing the manufacture of hollow articles such as bottles, pipes, tanks, hoses, and pipes. The use of polyamide compositions in these molding techniques has developed significantly.

However, in blow molding techniques, it is necessary to modify the rheological properties of the polyamide-based compositions in the molten state. Thus, many solutions have been proposed to modify and modify these rheological properties, such as increasing the polyamide molar mass by increasing the degree of polymerization or adding bifunctional extension chains.

It has also been suggested to add ionomeric elastomers or crosslinking agents as described in WO 93/04129, WO 90/07556 and WO 90/07555.

However, these compositions do not allow the preparation of articles or components of sufficient flexibility, which is particularly required for certain

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thermal machine components, such as components that are required to have some flexibility and high notch toughness.

These components are often exposed to voltage during assembly or during operation of the machine or equipment, which can cause destruction or simply prevent their installation immediately or during aging. The flexibility of the component must not be affected by temperature. Air and water pipes on heat machines are installed cold and then exposed to temperatures that may exceed 130 ° C when the machine is operating. In order to prevent destruction of these tubes, the flexibility of these components must be adequate both in cold and elevated temperatures (about 150 ° C).

Furthermore, the known means are not suitable for the preparation of pipes, hoses and pipes containing flexible parts which are connected to the rigid parts. It is therefore necessary to manufacture these components in the form of a plurality of elements, which are assembled or by means of mechanical connections such as collars or gaskets. In these systems, the flexible portions are usually made of an elastomeric material, such as thermoplastic rubbers.

One object of the present invention is to provide a polyamide-based composition whose rheological properties in the molten state allow blow molding and have increased flexibility, for example at low temperature.

It is another object of the present invention to provide compositions that allow the manufacture of components comprising flexible portions and rigid portions that are connected to each other. These components can advantageously be produced by a blow molding technique.

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SUMMARY OF THE INVENTION

For this purpose, the present invention provides a thermoplastic composition comprising a matrix based on a thermoplastic polymer polyamide and at least one notch toughener present at a concentration of 10 to 50% by weight of the composition wherein the modulus of elasticity of the composition is less than 1500 MPa.

According to a further preferred feature of the invention, the composition comprises a polyamide matrix plasticizer which is present at a concentration of 5 to 20% by weight of said polyamide matrix.

As a further component of the composition, it preferably comprises a chain extender of the polyamide matrix, which is present in a concentration of 0.05 to 5% by weight of the polyamide matrix.

The thermoplastic composition of the invention has a modulus of elasticity of less than 1000 MPa.

Thus, the composition of the present invention allows the preparation of components such as pipes, hoses and pipes, the degree of flexibility of which is sufficient to allow easy installation, for example in a heat machine, without the need for complex profile shaping.

The polyamide-based thermoplastic composition can further be used in combination with conventional thermoplastic polyamide compositions to obtain components comprising rigid portions and flexible portions that are joined to each other. In other words, the connection of these parts is achieved by means of the compatibility of the matrices constituting the components used, without external attachment or connection. Such components are prepared in particular using sequential injection molding, extrusion or compression techniques.

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The flexible parts of the components preferably have an expanded form which makes it possible to increase the additional flexibility of the tubes or pipes. The shape of the components of this kind is achieved in particular using blow molding techniques.

According to a preferred embodiment of the invention, the thermoplastic composition has a melt index of 0.5 g / 10 min to 8 g / 10 min.

This index is determined by using a 5 kg batch at 275 ° C. In particular, this flow index range permits the use of these compositions in blow molding techniques.

The compositions of the present invention further have an IZOD notch toughness measured at 23 ° C of greater than 800 J / m.

Thermoplastic polyamide matrices useful in the present invention include, in particular, semi-crystalline polyamides.

The term semi-crystalline polyamide suitable according to the present invention means polymers obtained by polycondensation of saturated aliphatic dicarboxylic acids such as adipic acid, azelaic acid, sebacic acid, dodecanedioic acid, fatty acids such as fatty acid dimers or mixtures thereof with primary diamines, preferably linear or branched saturated aliphatic primary diamines having 4 to 12 carbon atoms, such as hexamethylenediamine, trimethylhexamethylenediamine, tetramethylenediamine, m-xylenediamine or mixtures thereof; polyamides obtained either by direct homopolycondensation of ω-aminoalkanoic acid containing a hydrocarbon chain containing 4 to 12 carbon atoms or by hydrolytic opening and polymerization of lactams derived from these acids; copolyamides obtained from starting monomers of the above polyamides or other monomers such as terephthalic acid and / or isophthalic acid; diamines containing polyethylene glycol or polypropylene as the organic residue

·· · • ·· ·· «4 • • • · • 4 4 4 4 • 4 4 • · 4 4 444 444 • • • · ♦ 4 4 • 444 r ·· ··· • 4 44 44

a glycoiic chain; and mixtures of these polyamides or copolymers thereof.

To illustrate polyamides obtained by polycondensation of diacids and diamines, the following examples may be given:

- Nylon 4,6 (polymer of tetramethylenediamine and adipic acid),

- Nylon 6,6 (polymer of hexamethylenediamine and adipic acid),

- Nylon 6,9 (polymer of hexamethylenediamine and azelaic acid),

- Nylon 6,10 (polymer of hexamethylenediamine and sebacic acid),

Nylon 6.12 (polymer of hexamethylenediamine and dodecanedioic acid) a

- Nylon 12,12 (polymer of dodecanediamine and dodecanedioic acid).

To illustrate suitable polyamides obtained by homopolycondensation of lactams or α, ω-amino acids, the following examples may be given:

- Nylon 4 (4-aminobutyric acid or γ-butyrolactam polymer),

- Nylon 5 (polymer of 5-aminopentanoic acid or δ-amylolactam),

- Nylon 6 (ε-caprolactam polymer), '

- Nylon 7 (7-aminoheptanoic acid polymer),

- Nylon 8 (caprylactam polymer),

- Nylon '9 (9-aminononanoic acid polymer),

- Nylon 10 (polymer of 10-aminodecanoic acid),

- Nylon 11 (polymer of 11-aminoundecanoic acid),

Nylon 12 (polymer of 12-aminododecanoic acid or lauryllactam). .

The following examples can be used to illustrate the copolyamides:

- Nylon 6,6 / 6,10 (copolymer of hexamethylenediamine, adipic acid and sebacic acid); φφ φφ

- Nylon 6,6 / 6 (copolymer of hexamethylenediamine, adipic acid and caprolactam),

- Nylon 6/12

- Nylon 6/11

- Nylon 6 / 6.36.

Preferred polymers are Nylon 6,6, Nylon 6 or copolymers thereof or mixtures of these polyamides with other polyamides such as PA 6 / 6,36.

The polyamides are present in the composition at a preferred concentration of 55 to 70% by weight.

The notch toughening agent of the composition is preferably a compound having a Tg of less than 0 ° C and preferably less than -20 ° C. Further, for the preparation of compositions having a very low modulus of elasticity, for example less than 1000 MPa, the compound preferably has a modulus of less than 200 MPa.

The notch toughening agents of the present invention are polyolefins that have or are not elastomeric in nature.

According to a preferred embodiment of the invention, at least some of the flexibility modifying compounds of the composition comprise polar functional groups capable of reacting with the polyamide. These polar groups may be, for example, acid, anhydride, acrylic, methacrylic or epoxy functional groups.

These functional groups are usually grafted onto the macromolecular chains of the compounds.

Polyolefins suitable in accordance with the invention include polyethylenes, polypropylenes, polybutylenes or copolymers of ethylene and α-olefins such as ethylene / propylene dienes and ethylene-propylene copolymers.

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Very preferred polymers are very low density polyethylenes known as UDPE. These compounds are copolymers of ethylene and α-olefins containing 4 to 10 carbon atoms having a melt flow index (index measured at a batch of 2.16 kg at 190 ° C according to ASTM D 1238) of 0.5 to 7 g / 10 min, preferably less than 1 g / min and a density less than 0.9 g / m ³ , preferably 0.86 to 0.90 g / cm ³ .

The ULDPE polyethylene preferably comprises graft polar functional groups such as acid or anhydride functional groups, for example maleic anhydride functional groups. The mass concentration of these polar functional groups in the ULDPE poles, ethylene can vary within a wide range. This concentration may be, for example, 0.01 to 0.8% by weight based on the weight of the polyethylene. These ULDPE copolymers, as well as the process for their preparation, have been known for many years. It is mainly sold by the ENICHEM Company under the name Clearflex CH GO ^@ .

Copolymers grafted with polar functional groups, for example maleic anhydride, are known and are described in particular in European Patent Application No. 0581360 and 0646247.

The concentration of the notch toughness agent (or flexibility agent) in the composition depends in particular on the desired notch toughness. Preferably, this concentration is between 10 and 50% by weight relative to the polyamide matrix, preferably 20 to 40%.

According to another embodiment of the invention, the thermoplastic composition may comprise a polyamide matrix plasticizer. The plasticizer is preferably present in a concentration of 5 to 20% by weight based on the weight of the polyamide matrix.

Examples of suitable plasticizers are, for example, sulfonamides, such as o, p-toluenesulfonamide, N-ethyl-o, p-toluenesulfohamide, N-bu999. 9bolylbenzenesulfonamide, alkyl parahydroxybenzoates containing 1 to 20 carbon atoms, polyethylene glycols and polypropylene glycols.

In another embodiment, which is more preferred when the thermoplastic composition is blow molded, a chain extender is present in the polyamide matrix at a concentration of 0.05 to 5% by weight relative to the polyamide matrix.

The polymer chain extending agent allows the molar mass of the polyamide matrix to be increased to achieve the rheological properties of the composition in the molten state which are compatible with the blow molding process while maintaining a certain flexibility in the resulting product, i.e., reducing the modulus of elasticity of the composition.

Chain extender compounds include at least two functional groups capable of reacting with the terminal amino or polyamide functional groups. Preferred functional groups according to the invention are epoxy, anhydride or. isocyanate functionality.

Compounds of this type are described in many documents, such as US Patent Nos. 4,433,116, 4,417,031 and 4,417,032, and EP 0 295 905.

Thus, preferred difunctional compounds of the present invention are epoxy compounds. Examples of epoxy compounds are diepoxypolyglycols, diepoxybisphenols A, triglycidyl ethers, diglycidyl ethers and diepoxybisphenol F. These epoxy compounds preferably have a molar mass greater than 1000 g.

The compositions of the present invention may also contain one or more additional ingredients. These components are additives which do not modify the essential characteristics of the composition but improve, for example, its thermal or light stability or its tendency to lose shape. .of

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In this connection, mention may be made, for example, of heat stabilizers such as alkali metal halides, light stabilizers such as amines and hindered phenols, lubricants such as waxes and nucleating agents.

Of course, the composition of the present invention may contain pigments and dyes and other commonly used additives.

The compositions of the present invention can be prepared by mixing the individual components. This mixing operation is preferably and usually carried out, for example, in a single or twin screw extruder. The mixture is usually extruded into strands which are chopped into granules.

The granules so obtained are filled into molding units by compression, injection, extrusion or the like.

The compositions of the present invention are more particularly suitable for implementing blow molding techniques such as sequential blow molding of 2D or 3D blow molding.

The compositions of the present invention have physical and rheological properties which allow them to be used for the manufacture of components such as hollow components such as air tubes, fuel tubes or cooling systems for thermal machines.

The details, advantages and objects of the invention will be more clearly elucidated by means of the examples below, which are only illustrative of the invention and from one figure, which is a schematic view of a component comprising a rigid portion and a flexible portion.

Unless otherwise indicated, the percentages given in the examples below are expressed by weight relative to the total weight of the composition.

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The properties of the compositions are determined according to the standards mentioned above.

The melt viscosity index (MFI) is determined at 275 ° C at a batch of 5000 g.

The relative viscosity (rjrei) of polyamide 6 is determined according to a standard procedure (ISO 307, 1984) with a 1% by weight solution of polyamide in 95.7% by weight sulfuric acid.

DETAILED DESCRIPTION OF THE INVENTION

Example 1

The compositions of the present invention are prepared by mixing the various ingredients listed below in a W&P ZSK 40 twin screw extruder at a feed rate of 30 kg / hour and a screw rotation speed of 270 rpm at 270 ° C:

Polyamide 6 (η _Γβ ι = 4,8) 58,0% Notch modifier. toughness (PRIMEFLEX® AFG4W) 40.0%

S.l. chain extension (ARALDITE® GT7071) 0.80% Pigments (carbon black) 0.90% Lubricant (calcium stearate) 0.30%

This composition has the following characteristics: Melt Viscosity Index (MFI)

Modulus of elasticity

IZOD notch toughness

0.9 g / 10 min 1300 MPa 900 J / m

Notch toughness agent is ULDPE polyethylene sold by ENICHEM under the trade name PRIMEFLEX® AFG4W. This compound has a density of 0.885 g / cm ³ , viscosity index. melt 0.7-0.8 g / 10 min measured at 190 ° C at a batch of 2.16 kg and Tg -45 ° C,

A compound containing epoxy functional groups (equivalent number of epoxy11) was used as a chain extender (equivalent number of epoxy groups). 1.90 to 2.0 eq / kg), which is sold under the trade name ARALDITE® GT7071.

Either mineral carbon black or a mixture of mineral carbon black and nigrosine are used as black pigments.

Example 2

The novel composition is prepared according to the procedure described in Example 1, wherein the mixing takes place at 250 ° C.

The composition of this composition is as follows:

Polyamide 6 (η _Γθ ι = 3.8) 33.60%

Copolyamide 6 / 6-36 (NYCOA® 2012) 30.0%

Notch Modifier. toughness (PRIMEFLEX® AFG4W) 35.0% Sl. chain extension (ARALDITE® GT7071) 0.80%

Antioxidant. '0,30%

Lubricant (calcium stearate) ... . 0,30%

This composition has the following Melt Viscosity Index (MFI) Modulus of Elasticity

IZOD notch toughness characteristics:

1.2 g / 10 min 1300 MPa 1000 J / m

Example 3

The composition of the present invention is prepared according to the procedure of Example 2 and has the following composition:

Polyamide 6 (rj _re i = 3.8) 20.1 Copolyamide 6 / 6-36 (NYCOA® 2012) 48.5 Notch modifier. toughness (PRIMEFLEX® AFG4W) 30,0 Sl. chain extension (ARALDITE® GT7071) 0.80 Antioxidant 0.30 Lubricant (calcium stearate) 0.30

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This resource has the following characteristics:

Melt Viscosity Index (MFI) 1.9 g / 10 min

Modulus of elasticity 1300 MPa

IZOD notched toughness 1000 J / m

Example 4

The composition of the present invention is prepared according to the procedure of Example 2 and has the following composition:

Polyamide 6 (η _Γε ι = 3.8) 18.6% Copolyamide 6 / 6-36 (NYCOA® 2012) 45.0% Notch Modifier. toughness (PRIMEFLEX® AFG4W) 35.0% Sl. chain extension (ARALDITE® GT7071) 0.80% Antioxidant 0.30% Lubricant (calcium stearate) 0.30%

This composition has the following characteristics: Melt Viscosity Index (MFI)

Modulus of elasticity

IZOD notch toughness

1.5 g / 10 min 1200 MPa 1000 J / m

Example 5

The composition of the present invention was prepared as described in Example 2 and had the following composition:

Polyamide 6 (η _Γβ ι = 3.8)

Copolyamide 6 / 6-36 (NYCOA® 2012)

Notch Modifier. of toughness (PRIMEFLEX® AFG4W). Sl. chain extension (ARALDITE® GT7071) Antioxidant

Lubricant (calcium stearate) according to pos17,1%

41.5%

40.0%

0.80% 0.30% 0.30%

This composition has the following characteristics: Melt Viscosity Index (MFI)

Modulus of elasticity

IZOD notch toughness

1.2 g / 10 min 900 MPa 1100 J / m @ 2;

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Example 6

The composition of the present invention is prepared by the blend of Example 2 and has the following composition: Copolyamide 6 / 6-36 (NYCOA® 2012)

Notch Modifier. toughness (PRIMEFLEX® AFG4W)

Sl. chain extension (ARALDITE® GT7071) Antioxidant

Lubricant (calcium stearate) according to pos63,6%

35.0%

0.80% 0.30% 0.30%

This resource has the following characteristics:

Melt Viscosity Index (MFI) 2.2 g / 10 min

Modulus of elasticity 1000 MPa

IZOD notched toughness 1100 J / m

Example 7

The compositions of the present invention are prepared according to the procedure of Example 2, wherein the mixing is performed at 260 ° C and has the following composition:

Polyamide 6 (η '^ βΐ = 4.8) 64.4%

Notch Modifier. toughness (PRIMEFLEX® AFG4W) 28.0%

Plasticizer (N-BBSA or N-butylbenzenesulfonamide) 7.0%

Antioxidant 0,30%

Lubricant (calcium stearate) 0,30%

This resource has the following characteristics:

Melt Viscosity Index (MFI) 2.2 g / 10 min

Modulus of elasticity 800 MPa

IZOD notched toughness 1200 J / m

Example 8

The compositions of the present invention are prepared according to the procedure of Example 2, wherein the mixing is performed at 260 ° C and has the following composition:

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Polyamide 6 (η _Γβ ι = 4.8)

Notch Modifier. 'toughness (PRIMEFLEX® AFG4W)

Plasticizer (polyethylene glycol MW 200)

Antioxidant

Lubricant (calcium stearate)

64.7%

28.0% 7.0% 0.30% 0.30%

This resource has the following characteristics:

Melt Viscosity Index (MFI) 6.0 g / 10 min

Modulus of elasticity 500 MPa

IZOD notched toughness 1100 J / m

Example 9

The composition of the present invention was prepared as described in Example 2 and had the following composition:

Polyamide 6 (η _Γβ ι = 3.8)

Copolyamide 6 / 6,6 (NYCOA® 2062)

Notch Modifier. toughness (PRIMEFLEX® AFG4W) Plasticizer (N-BBSA or N-butylbenzenesulfonamide) Pigments (carbon black)

Antioxidant

Lubricant (calcium stearate) according to pos22,1%

5.0%

30.0% 10.0% 0.9% 2.0%

0,30%

This resource has the following characteristics:

Melt Viscosity Index (MFI) 4.2 g / 10 min

Flexibility modulus 300 MPa

IZOD notched toughness 1200 J / m

Example 10

The composition of the present invention is prepared according to the procedure of Example 2 and has the following composition:

Polyamide 6 (η _Γβ ι = 3,8) 21.1% Copolyamide 6 / 6.6 (NYCOA® 2062) 35.0% Notch Modifier. toughness (PRIMEFLEX® AFG4W) 30.0% Sl. chain extension (ARALDITE® GT7071) 1.0% • · ··· ···

Plasticizer (N-BBSA or N-butylbenzenesulfonamide) 10.0%

Pigments (carbon black) 0,9%

Antioxidant 2,0%

Lubricant (calcium stearate) 0,30%

This composition has the following characteristics: Melt Viscosity Index (MFI)

Modulus of elasticity

IZOD notch toughness

1.0 g / 10 min 300 MPa 1200 J / m

Example 11

The composition of the present invention is prepared according to the procedure of Example 2 and has the following composition:

Polyamide 6 (η _Γ βΐ = 5.2) '61, 8 % Copolyamide 6 / 6-36 (NyCOA® 2012) 30.0 'Q. 0 Notch Modifier. toughness (EXXELOR® VA 1801) 28.0 O. Plasticizer (N-BBSA or N-butylbenzenesulfonamide) 7.0 % Pigments (carbon black) 0.9 % Antioxidant 2,0 % Lubricant (calcium stearate) 0.30 % This resource has the following characteristics: Melt Viscosity Index (MFI) 5.0 g / 10 min Modulus of elasticity 700 MPa IZOD notch toughness 1200 J / m

Example 12

The composition of the present invention is prepared according to the procedure of Example 2 and has the following composition:

Polyamide 6 (η _Γε ι = 5,2) 39,8%

Copolyamide PA 6 / 6-9 (NYCOA® 2047) 30.0%

Notch Modifier. toughness (EXXELOR® VA 1801) 20.0%

Plasticizer (o, p-toluenesulfonamide) 7.0%

Pigments (carbon black) 0,9%

Φ Φ φ φ · φ φ φ φ φ φ φ φ φ φ φ φ φ φ φ φ φ φ φ φ φ φ φ φ φ φ φ φ φ

Antioxidant 2,0%

Lubricant (calcium stearate) 0,30%

This resource has the following characteristics:

Melt Viscosity Index (MFI) 7.0 g / 10 min

Modulus of elasticity 1400 MPa

IZOD notched toughness 1000 J / m

Example 13

The product, the shape of which is shown in the attached figure, is prepared by blow molding with gradual extrusion.

This product is manufactured on a sequential coextrusion machine having the trade name BATTENFELD 2D, consisting of two single screw extrusion units and a coextrusion die. Each extrusion unit includes a container.

The diameter of the extrusion units is 60 mm, the length / diameter ratio being 20 for the first unit and 24 for the second unit. The cartridge capacity is 0.7 L for the first unit and 1 L for the second unit.

The extrusion die has a diameter of 32 mm and a compression pressure of 25 tons.

The product shown in the figure is a tube comprising a first part 1 obtained by blowing the rigid polyamide, a second part 2 also obtained by blowing the rigid polyamide composition and a third middle portion 2 in expanded form prepared by blowing the polyamide composition according to Example 1.

Claims (17)

What is claimed is: 1. A thermoplastic composition comprising a matrix based on a thermoplastic polymer polyamide and at least one notch impact modifier present in a concentration of 10 to 50% by weight of the composition, the modulus of elasticity of said composition being less than 1500 MPa. and the IZOD notch toughness at 23 ° C is greater than 800 J / m. 2. A composition according to claim 1 comprising a polymeric matrix plasticizer present in a concentration of 5 to 20% by weight of the polymeric matrix. A composition according to any one of claims 1 or 2, characterized in that it comprises a polymer matrix extender compound that is present in a concentration of 0.05 to 5% by weight of the polymer matrix. A composition according to any one of claims 1 to 3, characterized by. by having a melt index of 0.5 g / 10 min to 8 g / 10 min, measured at a batch of 5 kg and a temperature of 275 ° C. Composition according to any one of claims 1 to 4, characterized in that it has a modulus of elasticity of less than 1000 MPa. The composition of any one of claims 1 to 5, wherein the notch toughness modifying agent is selected from the group consisting of compounds having a Tg of less than 0 ° C and a modulus of elasticity of less than 200 MPa. The composition of claim 6, wherein the notch toughness modifying agent is a compound selected from the group of polyolefins. ΦΦ · · Φ φ φ φ φ «« «« φ φ φ φ φ φ φ φ φ φ φ φ φ φ φ φ φ φ φ φ φ φ φ φ 8. The composition of claim 7 wherein at least some of the impact modifying agent comprises polar functional groups capable of reacting with the polyamide matrix. 9. The composition of claim 8 wherein the polar functional groups are selected from the group consisting of acid, anhydride, acrylic, methacrylic and epoxy functional groups. The composition of any one of claims 6 to 9, wherein the notch toughness modifying agent is polyethylene. (ULDPE) of very low density having a density of less than 0.9 and a melt index of 0.5 to 7 g / 10 min measured at 190 ° C at a batch of 2.16 kg, preferably 1 g / 10 min. The composition of any one of claims 2 to 10, wherein the plasticizer is selected from the group consisting of sulfonamides such as o, p-toluenesulfonamide, N-ethyl-o, p-toluenesulfonamide, N-butylbenzenesulfonamide, al. C1-C20 parahydroxybenzoates, polyethylene glycols and polypropylene glycols. A composition according to any one of claims 3 to 11, wherein the chain extending compound is an organic diepoxy, dianhydride or diisocyanate compound. Composition according to any one of claims 1 to 12, characterized in that the polyamide resin is selected from the group consisting of PA 6, PA 6,6, a copolymer thereof, PA 6 / 6.36, PA 6 / 6-9, PA 6.10, PA 6.12, PA 6.36, PA 6.11 / 6.12 or mixtures thereof. An article characterized in that it is obtained by molding a composition according to any one of claims 1 to 13. 99 · 9 99 99 9 · 9 99 9999 9999 9 · 999,999 · 9 9 · 9 · 9 · 999 999 - _Q 9 9 99 9 9 9 1 1b 9 · 9 9 9 · 9 999 99 99 99 An article comprising at least one phobic portion obtained by molding a composition according to any one of claims 1 to 14 and at least one rigid portion in association with said flexible portion, wherein the rigid portion is obtained by molding a matrix-based composition of thermoplastic material which is compatible with the polyamide of the flexible composition. 16. The article of claim 15 wherein the thermoplastic matrix of the rigid portion of the composition is a polyamide resin. 17. The article of any one of claims 15 and 16 wherein the flexible portion is in expanded form.