Conductive molding compound

Abstract

The invention relates to a moulding compound containing at least 50% by weight of a semi-crystalline polyamide component and containing a filler that imparts electrical conductivity to the moulding compound, the moulding compound having no crystallite melting point (Tm) below 50 DEG C, the polyamide component containing components A and B, A) a PA homopolymer of the PA X.Y or PA Z type, where X represents a diamine residue (DA), and B represents a polyamide residue of the PA X.Y or PA Z type. Y represents a dicarboxyl residue (DC), Z represents an alpha, omega-amino acid residue; b) a PA copolymer of the PA X '. Y' type wherein X 'represents a diamine residue (DA') and Y 'represents a dicarboxyl residue (DC'); wherein a portion of the diamine residues (DA ') are substituted with a polyether having at least two amino terminals or at least two hydroxyl terminals; wherein the proportion of the polyether in the sum of components A and B is from 0.5% by weight to 15% by weight, and wherein the proportion of the filler is from 2.5% by weight to 6% by weight, based on the total mass of the polyamide component and the filler. The invention also relates to methods of making and using the moulding compounds, and to hollow profiles comprising the moulding compounds.

Description

[0001] This application is a divisional application of the patent application for invention with the international application number PCT / EP2019 / 078240, filed on October 17, 2019, the Chinese national application number 201980084153.X, and the invention title "Conductive Molding Compounds".

[0002] The present invention relates to a semi-crystalline polyamide component as a constituent of moulding compounds, wherein the polyamide component does not have a microcrystalline melting point (T m ) below 50 °C.

[0003] Flexible tubes for the conveyance of liquid or gaseous media in motor vehicles are well known. This problem has previously been satisfactorily solved by single-layer tubes made of polyamide or other thermoplastic moulding compounds. In the case of these single-layer tubes, it has been found that even within the service life of a motor vehicle, the mechanical properties present after installation, such as high elongation at break and high impact resistance, do not change significantly due to the influence of cold or heat or due to contact with the medium, so as to cause pipeline failure.

[0004] More stringent environmental regulations have led to a move away from the further development and use of single-layer tubes and single-layer fuel containers as fuel lines. In both cases, the automotive industry not only requires sufficient fuel resistance but also an improved barrier effect against fuel components to reduce their emissions. This has led to the development of multi-layer hollow bodies using barrier layer materials. Such multi-layer composites, which contain not only a barrier layer but also other layers based on aliphatic polyamides, are known, for example, from EP 1216826A2.

[0005] Since polyamides have good mechanical properties, low water absorption capacity and insensitivity to environmental influences, polyamides are useful materials for the inner and outer layers. Adhesion between adjacent layers is desirable and can be ensured with an inserted adhesion-promoting layer. In the automotive industry, the temperature in the engine compartment has been increasing for some time, so the stability of hollow bodies used at these temperatures is required. Technical solutions including an adhesion-promoting layer based on, for example, polyolefins are unsuitable due to their low heat distortion resistance. EP1216826A2 solves this problem by using an adhesion-promoting layer containing a polyamide selected from PA6, PA66 and PA6 / 66, an optionally present polyamine-polyamide copolymer, and a polyamide selected from PA11, PA12, PA612, PA1012 and PA1212.

[0006] For example, in order to reduce the energy consumption of a motor vehicle engine, the trend towards "downsizing" to reduce component size while maintaining the same performance not only results in an increase in the temperature prevailing in the engine compartment, but also leads to a reduction in the size of injection valves. These valves are nozzles that inject fuel into the intake tract or combustion chamber of an internal combustion engine. The polar components present in the fuel require that the multi-layer tubes used be resistant to the extraction of components from the materials used. US 6467508 describes the problem of such extracts precipitating in the fuel and possibly clogging the injection valves. This problem is solved by using a "low precipitation polyamide" in the inner layer. A "low precipitation polyamide" is a washed polyamide obtained by the inconvenient and expensive pre-extraction with methanol. In this way, troublesome components such as oligomers are removed.

[0007] As the size of the nozzles is gradually reduced, the automotive industry not only requires a reduction in the extracts that precipitate out of the fuel, but also a reduction in the extracts that are soluble in the fuel. This requirement has been enhanced by the introduction of hybrid vehicles, since the internal combustion engines of these vehicles are not used for long periods. Thus, soluble extracts in the fuel can also cause nozzle blockage through drying. The extracts are not only the oligomers described in US 6467508, but also additives such as plasticizers and stabilizers of the molding compounds used.

[0008] In DE 3 724 997 C2 and DE 2 716 004 C3 as well as EP 0 566 755 B1, polyether-block-amides based on laurolactam are used for the polyamide block. Modified mixtures corresponding to nylon-12 are also mentioned in the Polyamid-Kunststoffhandbuch [Plastics Handbook - Polyamide], 3 / 4, 1998, Carl Hanser Verlag, page 872, paragraph 8.3.3. These blends show partial compatibility based on the co-crystallization of nylon-12 blocks with homopolyamides.

[0009] EP1884356 discloses blends of polyamide / polyamide elastomers (TPE-A); the addition of conductive additives is also mentioned in the list of possible additives. The blends disclosed contain both a large amount of polyether amide and a large amount of an impact modifier based on polyolefins.

[0010] The preparation of polyether amides is described, for example, in EP0459862B1 and CH642982. Here, polyether amides are prepared from polyamide sequences having carboxyl groups at both chain ends and polyoxyalkylene sequences having amino groups at both chain ends.

[0011] WO 2017 / 121961 A1 and WO 2017 / 121962 A1 claim protection for multi-layer tubes, where the inner layer has at least three different polyamides with different chain lengths. These layers can also include polyether-block-amides; they can also be conductive.

[0012] Typical thermoplastics have a specific surface resistance in the range of 10 16 -10 14 ohms (Ω), so that voltages of up to 15,000 volts can be built up. Effective antistatic agents can reduce the specific surface resistance of the plastic to 10 10 -10 9 ohms. In contrast, if the plastic is used in the electronic components of large devices, for example in the field of transformer or electrical switchgear manufacturing, or for various applications in automotive and aircraft structures, much higher levels of static charge dissipation must be achieved. In this case, conductive molding compounds must be used, which must have a specific surface resistance of less than 10 9 ohms. Additionally crucial is that in such plastic applications, not only the surface resistance, but also the volume resistance through plastic components with a thickness of at most a few millimeters must be in very much the same range, and in the case of components produced by injection molding, it is usually difficult to prevent the development of anisotropic effects.

[0013] Therefore, for the manufacture of conductive plastic components, only already conductive plastics, such as especially polyaniline, can be used, or plastics that can be characterized as electrical insulators above can be made conductive by using carbon black, especially conductive carbon black, carbon fibers, graphite, graphene, and / or carbon nanotubes (CNT).

[0014] Carbon nanotubes, together with graphite, diamond, amorphous carbon, and fullerenes, are another polymorph of elemental carbon. The carbon atoms are arranged in hexagons here. This structure corresponds to a single-atom or multi-atom layer of rolled-up graphite in order to form hollow cylinders with a diameter usually of a few nanometers and a length of up to a few millimeters. The basic difference between multi-wall and single-wall carbon nanotubes is also usually abbreviated as MWNT and SWNT in the literature. Due to van der Waals forces, carbon nanotubes have a strong tendency to bind into bundles, so it is necessary to untangle / disperse them by strong shear forces during the extrusion process without significant shortening. Typical commercial products are available from various manufacturers, and the following products are mentioned here by way of example: Bayer, Cyclics (previously called Electrovac), Nancycol, and Arkema and their C150P (trademark of Bayer AG, Germany), Baytubes C 150HP, Baytubes C 70P, Electrovac HTF 110FF, NC 7000 (trademark of Nanocyl SA, Belgium) and Graphistrength grade C100. Other manufacturers provide CMT in the form of masterbatches, such as Hyperion and C-Polymers.

[0015] Accordingly, the problem to be solved by the present invention is to provide a conductive molding compound which does not require any low molecular weight plasticizer or other extractables to improve mechanical properties and improve anti-aging properties.

[0016] This problem is solved by a semi-crystalline polyamide component as a component of the molding compound, wherein the polyamide component does not have a microcrystalline melting point (T m ) below 50 °C, as described in detail below and in the claims.

[0017] The present invention provides a molding compound comprising at least 50 wt%, preferably 60 wt%, more preferably 70 wt%, particularly preferably 80 wt%, especially preferably at least 90 wt% of a semi-crystalline polyamide component, and a filler conferring conductivity to the molding compound, characterized in that the molding compound does not have a microcrystalline melting point below 50 °C,

[0018] wherein the polyamide component comprises components A and B,

[0019] PA homopolymers of the APA X.Y or PAZ type, where X represents a diamine residue (DA), Y represents a dicarboxylic acid residue (DC), and Z represents an α,ω-amino acid residue;

[0020] B PA copolymers of PAX'.Y', where X' represents a diamine residue (DA') and Y' represents a dicarboxylic acid residue (DC');

[0021] wherein some of the diamine residues (DA') are replaced by a polyether having at least two amino terminals or at least two hydroxyl terminals;

[0022] wherein the proportion of the polyether in the sum of components A and B is 0.5 wt% - 15 wt%,

[0023] and wherein the proportion of the filler is 2.5 wt% - 6 wt%, based on the total mass of the polyamide component and the filler,

[0024] wherein at most 10 mol% of the PA homopolymer can be formed by other amide forming units,

[0025] wherein at most 10 mol% of the diamine residues (DA') can be replaced by a polyether having only one amino terminal or only one hydroxyl terminal.

[0026] The present invention also provides the use of the molding compound according to the present invention for the production of hollow profiles.

[0027] The present invention also provides single-layer or multi-layer hollow profiles which have at least one layer consisting of the moulding compound according to the present invention.

[0028] The moulding compounds according to the present invention, shaped articles (such as hollow profiles) comprising the moulding compounds according to the present invention, and the use of the present invention are described below by way of examples, but the present invention is not limited to these exemplary embodiments. When ranges, general formulae or classes of compounds are mentioned below, these include not only the corresponding ranges or groups of the explicitly mentioned compounds, but also all sub-ranges and subgroups of compounds which can be obtained by extracting individual values (ranges) or compounds. Where documents are cited in the context of the present specification, their entire contents are intended to form part of the disclosure of the present invention. Where percentages are given below, these are weight percentages unless otherwise stated. In the case of compositions, percentage figures are based on the entire composition unless otherwise stated. Where average values are given below, these are mass average values (weight average values) unless otherwise stated. Where measured values are given below, these are determined at a pressure of 101 325 Pa and a temperature of 25 °C unless otherwise stated.

[0029] The scope of protection includes commercially customary finished products and packaging forms of the products according to the present invention, including their own and any reduced-size forms, to the extent not defined in the claims.

[0030] The different units of the polyether are in a statistical distribution. The statistical distribution is a block structure having any desired number of blocks and any desired sequence, or they have a random distribution; they can also have an alternating structure or form a gradient on the polymer chain; more particularly, they can also form any mixed form in which groups having different distributions can optionally follow one another. As a result of the embodiments, a particular embodiment may lead to a limitation of the statistical distribution. For all regions not affected by the limitation, the statistical distribution remains unchanged.

[0031] One advantage of the moulding compound according to the present invention is that single-layer or multi-layer hollow bodies having an inner layer consisting of the moulding compound according to the present invention have high washout resistance. This is shown by testing on the tubes described in the examples using a test fuel according to ASTM D471-15 "Reference Fuel I". The test fuel is characterized in that it contains 15% by volume of methanol. Other methods for determining washout resistance may be known in the art; the preferred method according to the present invention is detailed in the examples. Soluble components as well as insoluble components can be extracted here. Preferably, less than 6 g of soluble components per square metre of the inner surface of the test specimen are extracted from the test specimen, preferably less than 5.5 g / m 2 。

[0032] Another advantage of the moulding compound according to the invention is that the crystallinity of the polyamide component consisting of components A, B and C is lower than that of a mixture comprising the same components A and C in the same amounts.

[0033] An advantage of the multi-layer hollow body according to the invention having an inner layer formed from the moulding compound according to the invention and a barrier layer is low fuel permeability. This is demonstrated by testing on the tubes described in the examples using a test fuel according to ASTM D471-15 “Reference Fuel I”. The test fuel is characterised in that it contains 15% by volume of methanol. Other methods of determining erosion resistance may be known in the art; the preferred method according to the invention is described in detail in the examples.

[0034] During a test duration of one day, when stored at 60 °C, preferably no more than 6 g / m 2 diffuses out from the test specimen, preferably less than 5.5 g / m 2 , more preferably less than 5.0 g / m 2 , particularly preferably less than 4.5 g / m 2 .

[0035] The amide-forming units are combinations of α,ω-amino acid residues or diamine residues with dicarboxyl residues. Preferred α,ω-amino acid residues are free amino acids or their lactams, more preferably ε-caprolactam, 11-aminoundecanoic acid, 12-aminododecanoic acid or the corresponding laurolactam.

[0036] The diamine residues are residues of hydrocarbons having an amino group at each end, where the amino groups can form the ends of the polymer but generally contribute to the formation of a chain with a valency.

[0037] Preferred hydrocarbons are aliphatic hydrocarbons, more preferably having 2-18 carbon atoms, particularly preferably 3-14 carbon atoms, especially preferably 4-12 carbon atoms. If the hydrocarbon has more than 3 carbon atoms, these are straight-chain, branched or cyclic, preferably straight-chain, more preferably straight-chain with up to 6 carbon atoms.

[0038] Particularly preferred diamine residues are ethylenediamine, 1,4-diaminobutane, 1,6-diaminohexane, 1,10-diaminodecane, 1,12-diaminododecane; particularly preferably 1,6-diaminohexane.

[0039] The dicarboxyl residues (DC) are residues of hydrocarbons having a carboxyl group at each end, where the carboxyl groups can form the ends of the polymer but generally contribute to the formation of a chain as a carbonyl group with a valency.

[0040] Preferred hydrocarbons are aliphatic hydrocarbons, more preferably having 3 - 18 carbon atoms, particularly preferably having 6 - 14 carbon atoms, and especially preferably having 8 - 12 carbon atoms. The hydrocarbons are further preferably straight-chain, branched-chain or cyclic, and more preferably straight-chain.

[0041] Preferred dicarboxylic acid residues are residues of succinic acid, glutaric acid, adipic acid, pimelic acid, suberic acid, azelaic acid, sebacic acid, dodecanedioic acid, and particularly preferably the residue of dodecanedioic acid.

[0042] The PA homopolymers include polyamides (PA) for Component A; preferred polyamides are PA 6, PA 11, PA 12, PA 4.6, PA 6.6, PA 6.9, PA 6.10, PA 6.12, PA 9.10, PA 9.12, PA 10.10, PA 10.12, PA 12.12; more preferably PA 6.6, PA 6.10, PA 6.12, PA 10.10; particularly preferably PA 6.10, PA 6.12, PA 10.10, and especially preferably PA 6.12.

[0043] Based on the total mass of the PA copolymer, the polyether content of the PA copolymer of Component B is preferably 8 wt% - 30 wt%, more preferably 9 wt% - 25 wt%, particularly preferably 10 wt% - 20 wt%, and especially preferably 12 wt% - 18 wt%.

[0044] The polyether preferably has 3 to 50 repeating units, more preferably 4 to 40, particularly preferably 5 to 30, and especially preferably 6 to 20, where the repeating units are connected to each other by oxygen atoms.

[0045] The polyether preferably does not contain nitrogen atoms without any hydrogen atoms, and further preferably does not contain amino groups of the formula -NH-, =NH in the polymer chain.

[0046] More preferably, the polyether only has alkyleneoxy units; preferably, if there are alkyleneoxy units having 3 - 18 carbon atoms, the polymer has stereoregularity, i.e., isotactic, syndiotactic, heterotactic, hemiisotactic, atactic.

[0047] Particularly preferred polyethers are composed of ethyleneoxy, propyleneoxy, and butyleneoxy units or mixtures thereof, where the mixture is random. Especially preferred polyethers are composed of ethyleneoxy and propyleneoxy units, or composed of n-butyleneoxy units, or composed of propyleneoxy units.

[0048] The polyether preferably has a number-average molecular weight M nNot exceeding 5000 g / mol, particularly preferably not exceeding 2000 g / mol, and especially preferably not exceeding 1000 g / mol, wherein the lower limit is at least 200 g / mol, preferably 300 g / mol, and more preferably 400 g / mol.

[0049] The polyether preferably does not have more than two amino terminals or two hydroxyl terminals, and more preferably has exactly two amino terminals or two hydroxyl terminals.

[0050] Based on the total mass of components A and B, the polyamide component of the molding compound according to the invention preferably has a polyether content of 1% by weight - 12% by weight, preferably 1.5% by weight - 9% by weight, particularly preferably 2.0% by weight - 8% by weight, and especially preferably 2.5% by weight - 7% by weight.

[0051] For the number of carbon atoms in the amide-forming units, the chain lengths of the PA copolymer and PA homopolymer of the polyamide component preferably differ from each other by an average of not more than 10%, wherein the difference is based on the higher value of the chain length. In the case of using PA copolymer PA10.12 and PA homopolymer such as PA10.10, the average value of PA 10.12 is 11, so the difference is 9.1%.

[0052] In the molding compound according to the invention, based on the total mass of the polyamide component and the filler for improving conductivity, i.e., the total mass of components A, B, and C, the proportion of the filler for improving conductivity (component C) is 2.5% by weight - 6% by weight. The lower limit of 2.5% by weight has the advantage of a sufficiently high conductivity and a sufficiently low resistance so that it can be used in electronic components of large equipment and in automotive and aircraft structures. A filler concentration greater than 6% by weight further results in a small notch impact resistance, indicating embrittlement of the material at too high a filler concentration.

[0053] The preferred filler for increasing conductivity does not form aggregates; thus, they are dispersible when shear force is introduced.

[0054] Further preferably, the crystallinity of the molding compound according to the invention is lower than the crystallinity of a mixture comprising equal amounts of the same components A and C (filler for increasing conductivity), wherein any other components of the molding compound are the same in type and amount.

[0055] The crystallinity is determined by methods of the prior art; the crystallinity is preferably calculated by equation (1)

[0056]

[0057] Parameter T within the scope of the present invention m 、T g and ΔH mIt is determined by means of DSC, preferably in accordance with EN ISO 11354-1:2016D, more preferably as described in the examples.

[0058] For calculating the crystallinity X C The value of ΔH m 0 Is taken from a table, such as van Krevelen "Properties of Polymers", 4th edition, 2009. Preferably, the following values are assumed:

[0059]

[0060] The moulding compound of the present invention preferably does not contain any ionic liquids to improve conductivity, as described, for example, in EP2635638A1 (US20130299750A1). Further preferably, the moulding compound according to the present invention does not contain any metal in elemental form.

[0061] Preferably, the moulding compound according to the present invention does not contain a plasticizer, preferably does not contain a low molecular weight plasticizer. Plasticizers herein are listed in DIN EN ISO 1043-3:2017, as well as esters of p-hydroxybenzoic acid having 2-20 carbon atoms in the alcohol component or amides of arylsulfonic acids having 2-12 carbon atoms in the amine component, preferably amides of benzenesulfonic acid; ethyl p-hydroxybenzoate, octyl p-hydroxybenzoate, isocetyl p-hydroxybenzoate, N-n-octyltoluenesulfonamide, N-n-butylbenzenesulfonamide or N-2-ethylhexylbenzenesulfonamide.

[0062] The moulding compound of the present invention is preferably prepared by melt mixing in a kneading unit, i.e., by means of shear forces from the respective components.

[0063] Therefore, the present invention also provides a method for preparing the moulding compound of the present invention, wherein the respective components are mixed by melt mixing.

[0064] The respective components of the moulding compound of the present invention can be added simultaneously or sequentially. Although in a preferred embodiment, in the case of masterbatch preparation, the filler can first be dispersed in component A or B (especially in component B), in which case the prepared masterbatch is subsequently diluted with the corresponding component B or A not present in the masterbatch, a method for preparing the moulding compound of the present invention in which components A and B and the filler are very particularly preferably mixed simultaneously by melt mixing is highly preferred. Any other components of the moulding compound of the present invention can be added simultaneously with or after components A and B and the filler.

[0065] Preferred carbon nanotubes are usually in the form of tubes formed from graphite layers. The graphite laminae are arranged concentrically around the axis of a cylinder. Carbon nanotubes are also referred to as carbon nanofibers. Their aspect ratio is at least 5, preferably at least 100, more preferably at least 1000. The diameter of the nanofibers is typically in the range from 0.003 to 0.5 μm, preferably in the range from 0.005 to 0.08 μm, more preferably in the range from 0.006 to 0.05 μm. The length of the carbon nanofibers is typically from 0.5 to 1000 μm, preferably from 0.8 to 100 μm, more preferably from 1 to 10 μm. The carbon nanofibers have a hollow, cylindrical core. The diameter of the cavity is typically from 0.001 to 0.1 μm, preferably from 0.008 to 0.015 μm. In a typical embodiment of the carbon nanotubes, the wall of the fiber around the cavity consists of, for example, 8 graphite laminae. The carbon nanofibers can here take the form of an agglomerate with a diameter of up to 1000 μm, which consists of a plurality of nanofibers. The agglomerates can have the form of a bird's nest, a combed yarn or an open mesh structure. Carbon nanotubes are synthesized, for example, in a reactor containing a carbon-containing gas and a metal catalyst, as described in US5643502A.

[0066] In addition to multi-walled carbon nanotubes (MWCNT), single-walled carbon nanotubes (SWCNT) can also be used according to the invention. SWCNT typically have a diameter in the range of a few nanometers, but are quite large in length relative to their cross-section, typically in the range of a few micrometers. The structure of SWCNT is derived from single-atom graphite laminae (graphene), which can be imagined as rolled up to form a seamless cylinder. SWCNT can be excellent electrical conductors. The achievable current density 10 9 A / cm 2 is about 1000 times higher than in the case of metal wires of copper or silver. The production of SWCNT is described, for example, in US5424054.

[0067] Further preferred is a molding compound comprising at least 70% by weight, particularly preferably 80% by weight, very particularly preferably at least 90% by weight of a semi-crystalline polyamide component and a filler which imparts electrical conductivity to the molding compound, characterized in that the molding compound does not have a microcrystalline melting point below 50 °C,

[0068] wherein the polyamide component comprises components A and B,

[0069] PA homopolymers of the APAX.Y or PAZ type, where X represents a diamine residue (DA), Y represents a dicarboxyl residue (DC), and Z represents an α,ω-amino acid residue;

[0070] B PA copolymers of the PAX'.Y' type, where X' represents a diamine residue (DA') and Y' represents a dicarboxyl residue (DC');

[0071] Some of these diamine residues (DA') are replaced by polyethers having two amino termini or two hydroxyl termini;

[0072] wherein the proportion of the polyether in the sum of components A and B is 0.5 wt% - 15 wt%,

[0073] and wherein the proportion of the filler is 2.5 wt% - 6 wt%, based on the total mass of the polyamide component and the filler;

[0074] wherein at most 10 mol% of the PA homopolymer can be formed from other amide-forming units;

[0075] wherein the PA copolymer of component B has a polyether content of 8 wt% - 30 wt%, based on the total mass of the PA copolymer.

[0076] Further preferred is a molding compound comprising at least 70 wt%, particularly preferably 80 wt%, especially preferably at least 90 wt% of a semi-crystalline polyamide component and a filler imparting conductivity to the molding compound, characterized in that the molding compound does not have a microcrystalline melting point below 50 °C,

[0077] wherein the polyamide component comprises components A and B,

[0078] PA homopolymers of the APA X.Y or PAZ type, wherein X represents a diamine residue (DA), Y represents a dicarboxyl residue (DC), and Z represents an α,ω-amino acid residue;

[0079] B PA copolymers of the PAX'.Y' type, wherein X' represents a diamine residue (DA') and Y' represents a dicarboxyl residue (DC');

[0080] Some of these diamine residues (DA') are replaced by polyethers having two amino termini or two hydroxyl termini;

[0081] wherein the proportion of the polyether in the sum of components A and B is 0.5 wt% - 15 wt%,

[0082] and wherein the proportion of the filler is 2.5 wt% - 6 wt%, based on the total mass of the polyamide component and the filler;

[0083] wherein at most 10 mol% of the PA homopolymer can be formed from other amide-forming units;

[0084] wherein the polyether has a number-average molecular weight Mn of not more than 5000 g / mol n ;

[0085] wherein for the number of carbon atoms in the amide-forming units, the chain lengths of the PA copolymer and the PA homopolymer of the polyamide component differ from each other by an average of not more than 10%, where the difference is based on the higher value of the chain lengths.

[0086] Further preferred is a molding compound comprising at least 70% by weight, particularly preferably 80% by weight, and very particularly preferably at least 90% by weight of a semi-crystalline polyamide component and a filler conferring electrical conductivity to the molding compound, characterized in that the molding compound does not have a microcrystalline melting point below 50 °C,

[0087] wherein the polyamide component comprises components A and B,

[0088] A The PA homopolymer is selected from PA 6, PA 11, PA 12, PA 4.6, PA 6.6, PA 6.9, PA 6.10, PA 6.12, PA 9.10, PA 9.12, PA 10.10, PA 10.12, PA 12.12;

[0089] B A PA copolymer of the PAX'.Y' type, where X' represents a diamine residue (DA') and Y' represents a dicarboxylic acid residue (DC');

[0090] wherein some of the diamine residues (DA') are replaced by a polyether having two amino terminals or two hydroxyl terminals;

[0091] wherein the proportion of the polyether in the sum of components A and B is 0.5% to 15% by weight,

[0092] and wherein the proportion of the filler is 2.5% to 6% by weight, based on the total mass of the polyamide component and the filler;

[0093] wherein at most 10 mol% of the PA homopolymer can be formed from other amide-forming units;

[0094] wherein the crystallinity of the molding compound is lower than that of a mixture comprising equal amounts of the same component A and the filler for increasing electrical conductivity, wherein any other components of the molding compound are the same in type and amount.

[0095] The molding compound according to the invention preferably contains other additives.

[0096] Preferred additives are oxidation stabilizers, UV stabilizers, hydrolysis stabilizers, impact modifiers, pigments, dyes and / or processing aids.

[0097] In a preferred embodiment, the molding compound contains an effective amount of an oxidation stabilizer, more preferably a combination of an effective amount of an oxidation stabilizer and an effective amount of a copper-containing stabilizer. Examples of suitable oxidation stabilizers include aromatic amines, sterically hindered phenols, phosphites, phosphonites, thiosynergists, hydroxylamines, benzofuranone derivatives, acrylyl-modified phenols, etc. Many types of such oxidation stabilizers are commercially available, such as those sold under the trade names Naugard 445, Irganox 1010, Irganox 1098, Irgafos 168, P-EPQ or Lowinox DSTDP. Generally, the molding compound contains about 0.01 wt% - about 2 wt%, preferably about 0.1 wt% - about 1.5 wt% of the oxidation stabilizer.

[0098] In addition, the molding compound may further contain a UV stabilizer or a light stabilizer of the HALS type. Suitable UV stabilizers are mainly organic UV absorbers, such as benzophenone derivatives, benzotriazole derivatives, oxalanilides or phenyltriazines. The HALS type light stabilizers are tetramethylpiperidine derivatives; these are inhibitors acting as free radical scavengers. The UV stabilizer and the light stabilizer can be advantageously used in combination. Many types of both are commercially available; regarding the dosage, the manufacturer's instructions can be followed.

[0099] The molding compound may additionally contain a hydrolysis stabilizer, such as monomeric, oligomeric or polymeric carbodiimides or bisoxazolines.

[0100] The molding compound may further contain an impact modifier. Impact-modifying rubbers for polyamide molding compounds form part of the prior art. They contain functional groups derived from unsaturated functional compounds, which are incorporated in the main-chain polymer or grafted onto the main chain. The most commonly used are EPM or EPDM rubbers grafted with maleic anhydride radicals. Such rubbers can also be used together with unfunctionalized polyolefins, such as isotactic polypropylene, as described in EP0683210A2 (US5874176A).

[0101] Examples of suitable pigments and / or dyes include iron oxides, zinc sulfides, ultramarine, aniline black, pearlescent pigments.

[0102] Examples of suitable processing aids include paraffin wax, fatty alcohols, fatty acid amides, stearates such as calcium stearate, paraffin wax, montanates or polysiloxanes.

[0103] The multi-layer hollow profile of the present invention has at least one layer made of the molding compound of the present invention, which is in direct contact with the liquid. This is preferably the innermost layer of the hollow body.

[0104] The liquid is preferably a mixture of chemical substances comprising hydrocarbons and at least one alcohol; more preferably, the liquid is a fuel suitable as a power fuel for an internal combustion engine; particularly preferably, the fuel is a motor vehicle fuel, such as diesel or gasoline.

[0105] The fuel preferably contains alcohols having 1 to 8 carbon atoms, more preferably methanol, ethanol, propanol, butanol or pentanol. Alcohols having at least three carbon atoms can be in their n-form, i.e., straight-chain and having a terminal hydroxyl group, or in their various isomeric forms; the hydroxyl group here can be a primary, secondary or tertiary hydroxyl group, preferably a primary hydroxyl group. More preferably, at least 80% by volume of the alcohol is a straight-chain hydrocarbon having a terminal hydroxyl group.

[0106] The fuel preferably comprises at least 7% by volume, more preferably at least 10% by volume, particularly preferably at least 13% by volume, and especially preferably at least 16% by volume of alcohol.

[0107] The single-layer or multi-layer hollow body according to the invention is preferably a tube or a container, preferably a component of a fuel conduction system, preferably a fuel pipeline or a fuel tank.

[0108] The layer preferably in contact with the liquid prepared from the moulding compound of the invention is conductive. The hollow body has a surface resistivity of not more than 10 9 Ω / square, preferably not more than 10 6 Ω / square. Suitable test methods are known in the prior art; preference is given to determining the surface resistivity as described in SAE J 2260 of November 2004.

[0109] The preferred multi-layer hollow body according to the invention has a so-called barrier layer. The barrier layer has a very low diffusion coefficient for fuel components. Suitable materials for the barrier layer are hydrofluorocarbons and ethylene-vinyl alcohol polymers. The preferred multi-layer hollow body preferably has a so-called EVOH barrier layer. EVOH is a copolymer of ethylene and vinyl alcohol. The ethylene content in the copolymer is preferably 20 - 45 mol%, especially 25 - 35 mol%. Many commercial grades are available. By way of example, reference is made to the company brochure "Introduction to Kuraray EVAL TM Resins", version 1.2 / 9810 from Kuraray EVAL Europe. In addition to EVOH according to the prior art, the barrier layer can contain other additives commonly used for barrier layer applications. Such additives are generally part of the know-how of the EVOH supplier.

[0110] According to the invention, the preferred multi-layer hollow body has a barrier layer (SpS) and a layer made of the molding compound according to the invention as the innermost layer (Si), wherein the hollow body has a surface resistivity of no more than 10 6 Ω / square according to SAE J 2260 of November 2004.

[0111] Between the barrier layer (SpS) and the innermost layer (Si) of the preferred multi-layer hollow body, additional layers can be provided, preferably at least one layer (HVi) that ensures adhesion between Si and SpS. Preferably, only an adhesion promoter layer is provided between SpS and Si. If the adhesion between SpS and Si is large enough, the adhesion promoter layer (HVi) can of course be omitted.

[0112] Adhesion promoters between the barrier layer and the molding compound layer according to the invention are known to those skilled in the art; preferred adhesion promoters are based on polyamides, preferably composed of a mixture of PA 6.12 and PA 6, more preferably composed of impact-modified polyamides, particularly preferably containing 60% to 80% by weight of PA 6.12, 10% to 25% by weight of PA 6, and 5% to 15% by weight of an impact modifier, where the mass ratio is selected so that they add up to 100% by weight.

[0113] Preferably, the layer provided on the inner side of the barrier layer in the preferred hollow body according to the invention does not contain a plasticizer as defined above. Further preferably, these layers only include the exact amounts of additives required, such as stabilizers and processing aids.

[0114] The preferred hollow body according to the invention preferably has at least one additional layer on the outer side of the barrier layer. These outer layers are also preferably layers containing at least 50% by weight, more preferably at least 60% by weight, even more preferably at least 70% by weight, particularly preferably at least 80% by weight, and especially preferably at least 90% by weight of polyamide.

[0115] These polyamides are preferably PA homopolymers of the PAX.Y or PAZ type as described above. The PA homopolymer of the outer layer (Sa) of the preferred hollow body is different from the PA homopolymer of the innermost layer (Si). Preferably, the PA homopolymer of the outer layer (Sa) is a PA of the PAZ type, more preferably PA11 or PA12, and particularly preferably PA12.

[0116] Between the outer layer (Sa) and the barrier layer (SpS) of the preferred hollow body according to the invention, additional layers can be provided, preferably at least one layer (HVa) that ensures adhesion between Sa and SpS. Preferably, only an adhesion promoter layer is provided between Sa and SpS. If the adhesion between Sa and SpS is large enough, the adhesion promoter layer (HVa) can of course be omitted.

[0117] The adhesion promoting layer (HVa) preferably does not contain plasticizers as defined above. Further preferably, the layer only comprises the exact amounts of additives required, such as stabilizers and processing aids.

[0118] Preferably, the adhesion promoting layers HVi and HVa are identical in terms of their chemical composition.

[0119] Further preferred is a multi-layer hollow profile having at least one layer composed of the moulding compound according to the invention, wherein this layer is in direct contact with a liquid and additionally has at least one barrier layer.

[0120] Further preferred is a multi-layer hollow profile having at least one layer composed of the moulding compound according to the invention and additionally having at least one barrier layer of a hydrofluorocarbon or ethylene alcohol polymer; wherein the layer arranged on the inner side of the barrier layer in the hollow body is free of plasticizers.

[0121] The hollow profiles according to the invention can also be coated with an additional elastomeric layer. Both crosslinked rubber compositions and thermoplastic elastomers are suitable for sheathing. The sheath can be applied to the multi-layer composite, for example, by co-extrusion, by crosshead die extrusion or by slipping a prefabricated elastomeric hose over the extruded multi-layer tube, with or without the use of additional adhesion promoters. The thickness of the sheath is generally from 0.1 to 4 mm, preferably from 0.2 to 3 mm.

[0122] Examples of suitable elastomers include chloroprene rubber, ethylene-propylene rubber (EPM), ethylene-propylene-diene rubber (EPDM), epichlorohydrin rubber (ECO), chlorinated polyethylene, acrylate rubber, chlorosulfonated polyethylene, silicone rubber, plasticized PVC, polyether ester amide or polyether amide.

[0123] The multi-layer composite can be manufactured in one or more stages, for example, by a single-stage method, by sandwich moulding, co-extrusion, co-extrusion blow moulding (such as including 3D blow moulding, extrusion of a parison into an open half-mould, 3D parison manipulation, suction blow moulding, 3D suction blow moulding, sequential blow moulding) or by a multi-stage method as described, for example, in US5554425.

[0124] The invention will be illustrated by way of examples in the following experiments.

[0125] In the examples, the following components / moulding compounds were used:

[0126] PA homopolymer 1: Extrusion moulding compound based on PA 6.12 (VESTAMIDD22) from EVONIK Resource Efficiency GmbH

[0127] PA homopolymer 2: Extrusion molding compound based on PA 10.10 (VESTMID DS22) from EVONIK Resource Efficiency GmbH

[0128] PA homopolymer 3: Extrusion molding compound based on PA 12 (VESTAMID L1901) from EVONIK Resource Efficiency GmbH

[0129] PEBA1: Extrusion molding compound based on PA6.12 from EVONIK Resource Efficiency GmbH, containing 25 wt% of a diamine - terminated polyether with a molar mass of 400 g / mol (Elastamin RP - 405, Huntsman)

[0130] PEBA2: Extrusion molding compound based on PA10.10 from EVONIK Resource Efficiency GmbH, containing 35.4 wt% of a dihydroxy - terminated polyether (polytetrahydrofuran) with a molar mass of 650 g / mol

[0131] PEBA3: Extrusion molding compound based on PA12 from EVONIK Resource Efficiency GmbH, containing 29 wt% of a dihydroxy - terminated polyether (polytetrahydrofuran) with a molar mass of 1000 g / mol

[0132] EVAL: EVOH (EVAL LA170B) from Kuraray containing 27 mol% ethylene

[0133] IM: Impact modifier: Exxelor VA1803 (9%) + 1% Lotader AX8900

[0134] Stabilizer: Mixture of Irgafos and Irganox

[0135] Adhesion promoter: Extrusion molding compound based on PA 6.12 (VESTAMID SX8002 or VESTAMID SX8080; SX8080 has the same index as SX8002 but contains no plasticizer) from EVONIK Resource Efficiency GmbH

[0136] Example 1, molding compound:

[0137] The following molding compounds were compounded by mixing the respective components in the melt in a Haake kneader (HAAKE Rheomix 600OS).

[0138] Table 1:

[0139] Composition of the molding compound of Example 1.

[0140] PEBA represents a PA copolymer, PE represents a polyether, and CNT represents a carbon nanotube;

[0141] The content of PE refers to the weight ratio of the polyether in the molding compound, without considering the mass of CNT;

[0142] The content of CNT is based on the mass ratio of the total molding compound

[0143]

[0144]

[0145] Molding compounds 13, 23, and 33 are molding compounds according to the present invention.

[0146] Example 2, Determination of thermal properties:

[0147] According to ISO 11357 (Perkin-Elmer), the glass transition temperature T during the first heating process was measured by DSC at a rate of 20 K / min g and the microcrystalline melting point T m , and the crystallinity X was calculated from the measurement of the melting enthalpy during the second heating process C .

[0148] Table 2: Thermal properties measured according to Example 2; nd represents values not measured

[0149]

[0150]

[0151] In all cases, it was observed that the crystallinity X C increased as the carbon nanotubes were added to the base polymer. In addition, in all cases, it was observed that when a small portion of the base polymer was replaced by PEBA, the crystallinity X C could be reduced. The molding compounds of the present invention do not have a microcrystalline melting point below 50 °C; this is also the case for molding compound 34 with a lower polyether content.

[0152] Example 3, Manufacture of hollow profiles:

[0153] A five-layer tube with an outer diameter of 8 mm and a total wall thickness of 1 mm was prepared by co-extrusion on a multi-layer tube system from Bellaform.

[0154] The comparative example only differed in the composition of the inner layer (layer I).

[0155] Table 3: Layer structure of the hollow profile of Example 3

[0156]

[0157]

[0158] Example 4: Tests

[0159] The following tests were carried out on the tubes from Example 3:

[0160] a) Tensile test (using MLT): Single-layer and multi-layer tubes were tested according to DIN EN ISO 527-1 at a draw speed of 100 mm / min. The test specimens had a length of approximately 200 mm, a clamping length of 100 mm, and a strain sensor spacing of 50 mm.

[0161] b) Impact test: The impact resistance of single-layer and multi-layer tubes was measured according to DIN 73378 at 23 °C.

[0162] The impact resistance of single-layer and multi-layer tubes was measured at -25 °C using a falling weight of 880 g according to VWTL 52435.

[0163] The impact resistance of single-layer and multi-layer tubes was measured at -40 °C using a falling weight of 500 g according to SAE J2260.

[0164] For all tests, 10 specimens with a length of approximately 100 mm were analyzed. After the stress test, visual inspection was carried out for damage.

[0165] c) Separation test: The separation test was carried out using a Zwick BZ 2.5 / TN1S tensile testing machine, to which a tensile device and a rotating deflection roller made of metal were connected so that the layers of the test specimen could be separated from each other. Using the separation test according to DIN EN ISO 2411, the adhesion between two layers was determined by measuring the force required to separate the two layers from each other. For this purpose, a tube section of a multi-layer tube with a length of 20 cm was longitudinally divided into three parts using a cutting device.

[0166] Before starting the measurement, the width of the sample was repeatedly measured at different points using a caliper, and the average value was taken for evaluation. Then, the initially separated end of one layer was held in a fixture that continuously pulled the layer from the second layer at an angle of 90°.

[0167] The layers were pulled apart at a test speed of 50 mm / min, while recording a graph of the force (in Newtons) versus the displacement (in millimeters) required. This graph was used to determine the separation resistance in N / mm based on the width of the adhesion contact area in the plateau region.

[0168] d) Fuel permeability: Using permeation measurement, determine how much fuel per day per meter of tube or per square meter of the inner tube area penetrates through the fuel line during static storage at 60 °C. For this purpose, a tube section with a length of 300 mm in each case is screwed onto a pressure-sealed storage container at one end and weighed, then filled with 300 ml of CM 15, and the second end is closed. These test specimens are stored in an explosion-proof heating cabinet with forced ventilation at 60 °C, and the filled tube is weighed again in order to be able to determine the mass loss and thus the permeated mass of the fuel over a specific time interval. The effective permeation length is 285 mm.

[0169] e) Erosion resistance: By determining erosion, find out how many g / m 2 of the inner tube surface is extracted from the multi-layer composite material in the form of soluble and insoluble components. For this purpose, a tube section with a length of 2 m is completely filled with the test fuel CM15 and closed, and stored at 60 °C for 96 h. After cooling, the tube is emptied into a beaker and rinsed with 20 ml of CM 15. The resulting liquid is stored at 23 °C for 24 hours. Then the test liquid is filtered under reduced pressure at 23 °C and rinsed with 20 ml of CM15. The filtered medium is evaporated in a fume hood at room temperature. The soluble extract is obtained by weighing. The filter is dried at 40 °C for 24 hours and weighed. The insoluble extract is determined using the difference from the original weight of the filter.

[0170] If less than 6 g / m 2 of soluble components and less than 0.5 g / m 2 of insoluble components are eroded, the test is considered qualified.

[0171] f) Thermal aging performance description of MLT (hot air circulation cabinet, 200 h at 150 °C and 1 h at 170 °C)

[0172] In a hot air circulation cabinet, the corresponding single-layer or multi-layer tube fittings with a length of approximately 100 or 200 mm are stored at an elevated temperature for a defined period of time. Here, it should be ensured that the fittings are freely suspended in the air circulation furnace without touching each other or the metal surface.

[0173] The length of the fittings depends on the subsequent mechanical tests. As described in b), test specimens with a length of approximately 100 mm are used for the tube impact test. They are stored at 150 °C for 200 hours, then conditioned in a standard climate of 23 °C / 50% relative humidity for > 24 hours, and the tube impact test is carried out as described in b). Similarly, the tube impact test is carried out on the fittings that have been pre-stored at 170 °C for 1 h.

[0174] g) The insulation resistance and its variation were determined by storing the fuel at 60 °C with CM 15, CE10, and FAM B.

[0175] The resistance was measured for at least three pipe segments with a length of 42 cm according to SAE J 2260 - 1996. For this purpose, the inner pipe surface was made to contact a plug with a defined length and diameter at the pipe ends. A test voltage between 10 V and 500 V was used to measure the resistance in the range of 10 2 to 10 14 Ω, and it was converted to the required surface resistivity with the unit "ohm per square" using the internal pipe area between the plugs.

[0176] Then, one end of the pipe segment was screwed onto the storage container and weighed, then filled with 300 ml of test fuel (CM15), and the second end was sealed. The pipe was placed below the storage container so that during storage and electrical measurement, the inner pipe surface was completely filled with fuel. The inner layer was in contact with the support sleeve at the pipe end through a metal threaded connection, and the resistance was measured directly after filling. The test specimens were stored in an explosion-proof heating cabinet with forced ventilation at 60 °C and cooled to 23 °C at fixed time intervals to determine the resistance change, and the test time was about 1000 hours. In parallel with the resistance, the absolute length of the free pipe cross-section was determined with a tape measure between the threaded connections, and the change in length was determined with a micrometer in the range of 0% to 5%.

[0177] If the measured resistance is less than 10 6 ohms per area, the test is considered qualified.

[0178] The compositions of the test fuels CE 10, CM 15, and FAM B are in the references of SAE J2260 - 1996; CM 15 corresponds to ASTM D471 - 15, "Reference Fuel I" (isooctane / toluene, methanol); FAM B corresponds to the test liquid of DIN 51604 - 2 (1984); CE 10 corresponds to a mixture of "Fuel C" according to ASTM D471 - 15 plus 10 ± 1 vol% ethanol.

[0179] The results are shown in Table 4.

[0180] Table 4: Test results of the pipes according to Example 3

[0181]

[0182] Example 5 - Molded plastics with different filler contents

[0183] First, a filler-containing masterbatch was prepared using a Nanocyl twin-screw extruder, based on polyether-modified polyamide (PA612.6T, ground powder) with a 10% CNT concentration.

[0184] Then dilute the masterbatch in a twin-screw extruder and add polyamide, impact modifier, stabilizer and dye. The components and filler content of the resulting molding mixture are shown in Table 5.

[0185] Table 5 - Formulation

[0186]

[0187] Prepare test specimens using the molding compound. For the notched impact test, these are injection molded / multi-purpose test specimens with dimensions of 170×10×4 mm 3 For electrical tests, extrude tapes with a thickness of 1 mm.

[0188] The following Table 6 shows the results of the notched impact test and electrical test as well as the test conditions.

[0189] Table 6 - Tests

[0190]

[0191] It is clearly seen that the notched impact resistance is reduced by more than 6%. Additionally, the specific resistance is too high at below 2.5%.

Claims

1. A molding compound comprising at least 50% by weight of a semi-crystalline polyamide component and a filler imparting electrical conductivity to the molding compound, characterized in that, The molding compound does not have a microcrystalline melting point (T m ) below 50 °C wherein the polyamide component comprises components A and B, A PA homopolymer of the APAX.Y or PA Z type, where X represents a diamine residue (DA), Y represents a dicarboxylic acid residue (DC), and Z represents an α,ω-amino acid residue; B A PA copolymer of the PAX'.Y' type, where X' represents a diamine residue (DA') and Y' represents a dicarboxylic acid residue (DC'); wherein some of the diamine residues (DA') are replaced by a polyether having at least two amino terminals or at least two hydroxyl terminals; wherein the proportion of the polyether in the sum of components A and B is 0.5% - 15% by weight, and wherein the proportion of the filler is 2.5% - 6% by weight, based on the total mass of the polyamide component and the filler; wherein at most 10 mol% of the PA homopolymer can be formed from other amide-forming units; wherein at most 10 mol% of the diamine residues (DA') can be replaced by a polyether having only one amino terminal or only one hydroxyl terminal.

2. The molding compound according to claim 1, wherein the PA copolymer of component B has a polyether content of 8% - 30% by weight, based on the total mass of the PA copolymer.

3. The molding compound according to any one of claims 1 and 2, wherein the polyether has a number average molecular weight M of not more than 5000 g / mol n .

4. The molding compound according to any one of claims 1 to 3, wherein for the number of carbon atoms in the amide-forming units, the chain lengths of the PA copolymer and the PA homopolymer of the polyamide component differ from each other by an average of not more than 10%, where the difference is based on the higher value of the chain lengths.

5. The molding compound according to any one of claims 1 to 4, characterized in that, the crystallinity of the molding compound is lower than that of a mixture comprising equal amounts of the same component A and the filler for increasing electrical conductivity, where any other components of the molding compound are the same in type and amount.

6. The molding compound according to any one of claims 1 to 5, characterized in that, it does not contain a plasticizer.

7. Use of the molding compound according to any one of claims 1 to 6 for the production of hollow profiles.

8. A single-layer or multi-layer hollow profile having at least one layer composed of the molding compound according to any one of claims 1 to 6.

9. The single-layer or multi-layer hollow profile according to claim 8, having at least one barrier layer.

10. The single-layer or multi-layer hollow profile according to any one of claims 8 and 9, wherein the layer provided on the inner side of the barrier layer disposed in the hollow body does not contain a plasticizer.

11. A method for producing the molding compound according to any one of claims 1 to 6, characterized in that, the components are mixed by melt mixing.

12. The method according to claim 11, characterized in that, components A and B and the filler are mixed with each other simultaneously.

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