WO2010102731A1

WO2010102731A1 - Mould consisting of carbon nanoparticle polymer blends having the gradient property of electric volume conductivity

Info

Publication number: WO2010102731A1
Application number: PCT/EP2010/001225
Authority: WO
Inventors: Michael Bierdel; Sigurd Buchholz; Volker Michele; Leslaw Mleczko; Reiner Rudolf; Aurel Wolf
Original assignee: Bayer Materialscience Ag
Priority date: 2009-03-13
Filing date: 2010-02-27
Publication date: 2010-09-16
Also published as: DE102009012673A1; TW201037735A

Abstract

A method for producing electrically conductive moulds having the gradient property of electric volume conductivity from a thermoplastic carbon nanoparticle polymer composite is described, and moulds produced according to said method.

Description

Shaped bodies of carbon nanoparticle polymer blends with gradient properties of the electrical volume conductivity

The invention is based on known methods for producing electrically conductive moldings by injection molding of thermoplastic polymers. The invention relates to a process for the production of electrically conductive moldings having a gradient property of the electrical volume conductivity of a thermoplastic carbon nanoparticle polymer composite material, as well as moldings produced by this process.

The production of electrically conductive polymer composites is basically known and z. For example, DE 10336473 describes a process for introducing conductive fibers into a polymeric material by means of extruders.

Novel conductive fibers are the carbon nanotubes that are gaining in importance. Under carbon nanotubes are understood in the prior art mainly cylindrical carbon tubes with a diameter between 1 and 500 nm and a length which is a multiple of the diameter. These tubes consist of one or more layers of ordered carbon atoms and have a different nucleus in morphology. These carbon nanotubes are for example also referred to as "carbon fibrils" or "hollow carbon fibers".

Carbon nanotubes have long been known in the literature. Although Iijima, Nature 354, 56-58, 1991, is commonly referred to as the discoverer of nanotubes, these materials, particularly fibrous graphite materials having multiple layers of graphite, have been known since the 1970s and early '80s, respectively. Tates and Baker (GB 146993 OAl, 1977 and EP 56004 A2) described for the first time the deposition of very fine fibrous carbon from the catalytic decomposition of hydrocarbons. However, carbon filaments made from short-chain hydrocarbons are no closer to theirs

Diameter characterized.

Typical structures of these carbon nanotubes are those of the cylinder type. In the cylindrical structures, a distinction is made between the single walled carbon nanotubes and the multiwalled carbon nanotubes. Common procedures too Their production includes, for example, arc discharge, laser ablation, chemical vapor deposition (CVD) and chemical vapor deposition (CCVD process).

From Iijima, Nature 354, 1991, 56-8, the formation of carbon tubes in the arc process is known, consisting of two or more graphene layers and rolled up into a seamlessly closed cylinder and nested together. Depending on the roll-up vector, chiral and achiral arrangements of the carbon atoms relative to the longitudinal axis of the carbon fiber are possible.

Structures of carbon tubes in which a single contiguous graphene layer (so called scroll type) or interrupted graphene layer (so-called onion type) is the basis for the construction of the nanotube were first reported by Bacon et al., J. Appl. Phys. 34, 1960, 283-90. The structure is called Scroll Type. Later, corresponding structures were also found by Zhou et al., Science, 263, 1994, 1744-47 and by Lavin et al., Carbon 40, 2002, 1123-30.

The object of the invention was to produce moldings from a carbon nanotube polymer composite by injection molding so that they have the highest possible electrical conductivity at the surface.

This object is achieved according to the invention in that the shaped bodies are produced by injection molding under the processing conditions according to the invention in such a way that they have a high electrical conductivity on the molded body surface and a decreasing electrical conductivity (conductivity gradient) in a layer near the surface perpendicular to the surface in the depth of the material , wherein the electrical conductivity or the electrical resistance at the surface at different points of the molding may be different and also different gradients can be set.

It has been found that, in particular with CNT polymer composites, not as is known from conventional gradient materials, the different properties are achieved by an inhomogeneous distribution of the fillers and reinforcing materials in the matrix or multilayer structure of the molded bodies, but by a special combination of the Injection molding parameters injection speed, mass and tool temperature can be achieved. The invention relates to a process for the production of electrically conductive moldings by injection molding of thermoplastic polymers and carbon nanoparticles, wherein the moldings have a gradient of electrical resistance perpendicular to the surface in a near-surface layer, such that the electrical resistance increases perpendicular to the surface, in particular in one near-surface layer which corresponds to a quarter of the wall thickness at the location of the shaped body with the smallest wall thickness, preferably with a gradient corresponding to 2 orders of magnitude per millimeter, more preferably 3 orders of magnitude per millimeter.

Particularly preferred is a method, characterized in that

a) initially to fill the cavity of a mold, the just sufficient minimum injection speed is determined such that in a series of experiments, the injection rate is reduced at constant other process parameters successively until the injection mold is no longer completely filled and the minimum injection speed at which the mold is straight could still be filled, is finally set.

b) the melt temperature is adjusted by injection molding based on the base polymer or polymer mixture used at least 20 ⁰ C and at most 160 ⁰ C above the minimum processing temperature of the polymer or polymer mixture, and

c) the mold temperature of the molding tool in the injection molding based on the polymer or polymer mixture used below the

Glass transition temperature (amorphous thermoplastics) or below the melting temperature (semi-crystalline thermoplastics) is adjusted so that the molding can be removed from the mold just without delay.

The term "minimum processing temperature" of a polymer in injection molding processing is understood as meaning the mass temperature of the polymer at which the polymer can barely be processed. In the book "Material Guide Plastics" (authors: Hellerich, Harsch, Haenle, Hanser Verlag, 9th edition, 2004, ISBN 3-446-22559-5) for a variety of polymers typical melt temperatures (processing temperatures) and mold temperatures for the processing by injection molding (see Table 1). Table 1

The numbers in brackets are for heat-resistant types.

Another object of the invention is an electrically conductive molded article of a thermoplastic carbon nanoparticle polymer composite material, characterized in that the shaped body is made by injection molding of thermoplastic polymers and carbon nanoparticles and has a gradient of electrical conductivity, such that the electrical conductivity at the surface is high and perpendicular to the surface decreases to a minimum, which is at least 0.1 millimeters below the surface and at most in the middle of the material.

Preference is given to an electrically conductive molded article of a thermoplastic carbon nanoparticle polymer composite material, characterized in that the shaped article is produced by injection molding from thermoplastic polymers and carbon nanoparticles and has a gradient of electrical conductivity, such that the electrical conductivity at the surface is high and perpendicular to Surface area decreases to a minimum, at least 0.1 millimeters below the surface and maximum in the middle of the material is and by a factor of 100, preferably by a factor of 1000 lower electrical conductivity than the electrical conductivity at the surface.

Particularly preferred is an electrically conductive molded body made of a thermoplastic carbon nanoparticle polymer composite material, characterized in that the shaped body is made by injection molding of thermoplastic polymers and carbon nanoparticles and has a gradient of electrical conductivity, such that the electrical conductivity at the surface is high and vertical decreases to the surface, to a minimum with a

Gradients corresponding to a decrease in electrical conductivity by 2 orders of magnitude per millimeter, preferably 3 orders of magnitude per millimeter.

In the case of the moldings described here, the surface resistance is in particular in the range from 10 ^Å l ohms / sq to 10 ^Λ 10 ohms / sq.

As carbon nanoparticles, graphite-like nanoparticles are preferably used in the process according to the invention.

The graphitic nanoparticles are particularly preferably single-layered or multi-layered graphite structures.

Particularly preferred are the single or multilayer graphite structures in the form of graphenes or carbon nanotubes or mixtures thereof. Particularly preferred are carbon nanotubes.

The graphitic nanoparticles preferably have a diameter in the range of 1 to 500 nm, preferably a diameter in the range of 3 to 100 nm and particularly preferably a diameter of 5 to 50 nm.

Particularly suitable for the production of new moldings are single or multilayered, single-walled or multi-walled carbon nanotubes (CNT), carbon nanofibers in herringbone or platelet structure or else nanoscale graphites or graphenes, as described, for example, in US Pat. B. are accessible from highly expanded graphite. Especially suitable are multi-walled Koh korstoffnanoröhrchen.

The proportion of carbon nanoparticles in a preferred embodiment of the invention is from 0.2 to 15% by weight, preferably from 0.5 to 10% by weight, particularly preferably from 1 to 7% by weight, based on the mass of the molding , A further preferred embodiment of the new process is characterized in that the mold temperature of the molding tool according to c) in said in Table 1 Temperature range T _We i _kzeug - _m i _n up to 20 ° above the recommended mold temperature Twe _RKZ eug- _m a _x ' for injection molding is set.

The invention further relates to novel molded articles made of a thermoplastic carbon nanoparticle polymer composite, which are produced by the method described above. Such shaped bodies are also referred to below as "gradient moldings".

These include, in particular, shaped bodies which have different electrical conductivities and different gradients of electrical conductivity at different locations.

Carbon nanotubes which can be used in the context of the invention are all single-walled or multi-walled carbon nanotubes of the cylinder type, scroll type or onion-like structure. Preference is given to using multi-walled carbon nanotubes of the cylinder type, scroll type or mixtures thereof.

Carbon nanotubes having a ratio of length to outer diameter of greater than 5, preferably greater than 100, are particularly preferably used.

The carbon nanotubes are particularly preferably used in the form of agglomerates, the agglomerates in particular having an average diameter in the range of 0.05 to 5 mm, preferably 0.1 to 2 mm, particularly preferably 0.2 to 1 mm.

The carbon nanotubes to be used have particularly preferably essentially an average diameter of 1 to 500 nm, preferably 3 to 100 nm, particularly preferably 5 to 50 nm.

In contrast to the initially mentioned known CNTs of the scroll type with only one continuous or interrupted graphene layer, the Applicant has also found CNT structures which consist of several graphene layers, which are combined into a stack and rolled up (multiscroll type). These carbon nanotubes and carbon nanotube agglomerates thereof are, for example, the subject of the still unpublished German patent application with the official file reference 102007044031.8. Their content hereby becomes the disclosure content of the CNT and its manufacture Registration included. This CNT structure is similar to the simple scroll type carbon nanotubes as the structure of multi-walled cylindrical monocarbon nanotubes (cylindrical MWNT) to the structure of single-wall cylindrical carbon nanotubes (cylindrical SWNT).

Unlike the onion-type structures, the individual graphene or graphite layers in these carbon nanotubes, seen in cross-section, evidently run continuously from the center of the CNT to the outer edge without interruption. This can be z. For example, it will be possible to provide improved and faster intercalation of other materials in the tube framework, as more open edges than the entry zone of the intercalates are available compared to single scroll CNTs (Carbon 34, 1996, 1301-3) or onion-like CNTs (Science 263, 1994, 1744-7).

The methods known today for the production of carbon nanotubes include arc, laser ablation and catalytic processes. In many of these processes, carbon black, amorphous carbon and high diameter fibers are by-produced. In the catalytic process, a distinction can be made between the deposition on supported catalyst particles and the deposition on in-situ formed metal centers with diameters in the nanometer range (so-called F low processes). In the production via the catalytic deposition of carbon at reaction conditions gaseous hydrocarbons (hereinafter CCVD, Catalytic Carbon Vapor Deposition) are given as possible carbon donors acetylene, methane, ethane, ethylene, butane, butene, butadiene, benzene and other carbon-containing reactants , Preference is therefore given to using CNTs obtainable from catalytic processes.

The catalysts usually include metals, metal oxides or decomposable or reducible metal components. For example, in the prior art, the metals mentioned for the catalyst are Fe, Mo, Ni, V, Mn, Sn, Co, Cu and other subgroup elements. Although the individual metals usually have a tendency to promote the formation of carbon nanotubes, according to the prior art, high yields and low levels of amorphous carbons are advantageously achieved with those metal catalysts based on a combination of the above-mentioned metals. CNTs obtainable using mixed catalysts are therefore preferred to use. Particularly advantageous catalyst systems for the production of CNTs are based on combinations of metals or metal compounds containing two or more elements from the series Fe, Co, Mn, Mo and Ni.

The formation of carbon nanotubes and the properties of the formed tubes are known to depend in a complex manner on the metal component used as a catalyst or a combination of several metal components, the catalyst support material optionally used and the interaction between catalyst and support, the educt gas and - partial pressure, an admixture of hydrogen or other gases, the reaction temperature and the residence time or the reactor used.

A particularly preferred method for the production of carbon nanotubes is known from WO 2006/050903 A2.

In the various methods mentioned so far using various catalyst systems, carbon nanotubes of various structures are produced, which can be removed from the process predominantly as carbon nanotube powder.

Carbon nanotubes which are more suitable for the invention are obtained by processes which are described in principle in the following references:

The production of carbon nanotubes with diameters smaller than 100 nm is described for the first time in EP 205 556 Bl. For the preparation here light (ie, short- and medium-chain aliphatic or mononuclear or dinuclear aromatic) hydrocarbons and an iron-based catalyst are used, are decomposed at the carbon carrier compounds at a temperature above 800-900 ⁰ C.

WO86 / 03455A1 describes the production of carbon filaments having a cylindrical structure with a constant diameter of 3.5 to 70 nm, an aspect ratio (length to diameter ratio) greater than 100 and a core region. These fibrils consist of many continuous layers of ordered carbon atoms arranged concentrically about the cylindrical axis of the fibrils. These cylindrical nanotubes were prepared by a CVD process from carbonaceous compounds by means of a metal-containing particle at a temperature between 850 ⁰ C and 1200 ⁰ C. From WO2007 / 093337A2 a method for the preparation of a catalyst is known, which is suitable for the production of conventional carbon nanotubes with a cylindrical structure. When using this catalyst in a fixed bed, higher yields of cylindrical carbon nanotubes with a diameter in the range of 5 to 30 nm are obtained.

An entirely different way of producing cylindrical carbon nanotubes has been described by Oberlin, Endo and Koyam (Carbon 14, 1976, 133). In this case, aromatic hydrocarbons, such as benzene, are reacted on a metal catalyst. The resulting carbon tube shows a well-defined, graphitic, hollow core about the diameter of the catalyst particle on which there is further less graphitic ordered carbon. The entire tube can be graphitized by treatment at high temperature (2500 ^° C - 3000 ^° C).

Most of the above processes (with arc, spray pyrolysis or CVD) are used today for the production of carbon nanotubes. The production of single-walled cylindrical carbon nanotubes, however, is very complex in terms of apparatus and proceeds according to the known processes with very low formation rate and often also with many secondary reactions which lead to a high proportion of undesired impurities, i. the yield of such processes is comparatively low. Therefore, the production of such carbon nanotubes is still extremely technically complicated today and they are therefore used mainly for highly specialized applications in small quantities. Their application, however, is conceivable for the invention, but less preferred than the use of multi-wall CNTs of the cylinder or scroll type.

The production of multi-walled carbon nanotubes, in the form of nested seamless cylindrical nanotubes or also in the form of the described scroll or onion structures, today takes place commercially in large quantities, predominantly using catalytic processes. These processes usually show a higher yield than the above-mentioned arc and other processes and today are typically carried out on the kg scale (several hundred kilo / day worldwide). The MW carbon nanotubes produced in this way are generally much cheaper than the single-walled nanotubes and are therefore used, for example. used as a performance-enhancing additive in other materials.

In principle, all known thermoplastic polymers are suitable as thermoplastic polymers for the novel moldings and their production process. Preferably, the Moldings on the thermoplastic polymers of the series: polycarbonate (PC), polyamide (PA), in particular polyamide 6, 66 or 12 (PA 6, PA 66, PA 12), polystyrene (PS), poly (styrene-acrylonitrile) (SAN) , Acrylonitrile-butadiene-styrene block copolymers (ABS), polyacrylate, in particular polymethyl (meth) acrylate (PMMA), poly (oxymethylene) POM, polyvinyl chloride (PVC), polyesters, in particular polyethylene terephthalate (PET), polybutylene terephthalate (PBT) polyalkylenes, in particular polyethylene (PE) and polypropylene (PP), polyetheretherketone (PEEK), polyphenylene ether (PPE), polyphenylene sulphide (PPS), polyurethane (TPU). Two or more of the abovementioned polymers can also be present in particular as a mixture or blend in the molding. Particularly preferred are blends of polycarbonate (PC) with ABS or PBT and blends of polyphenylene ether (PPE) and PA.

A significant advantage of the invention is that completely different types of gradient moldings with different electrical conductivity at the surface and different conductivity gradient can be generated procedurally only by adjusting the process parameters in the injection molding by the inventive method. In this way it is possible to adapt in a simple manner functional components with different electrical conductivities targeted to specific applications. Functional components with different electrical properties in the depth of the material, in which the electrical conductivity increases again after passing through the minimum and in the middle of the molding may well be higher than at the surface, are increasingly used in various high technology areas.

The moldings according to the invention find particular use for the production of antistatic or electrically conductive housings, eg for domestic and electrical appliances or for components of motor vehicles, for which a high surface conductivity is of great importance.

Examples

Exemplary embodiments of the invention will be explained in more detail below with reference to the figures. Show it:

Fig.l a molded part produced by injection molding in the form of a round plate, wherein the surface resistance in the z-direction is variable

2 shows a measuring arrangement for determining the surface electrical resistance of the CNT polymer composites

Fig. 1 shows an example of a section through a round plate (diameter 80 mm and thickness 2 mm) perpendicular to the surface and the corresponding resistance profile in the cutting plane. From the resistance profile shown schematically in Fig. 1, it can be seen that in the first case, the electrical resistance in the z-direction (i.e., across the thickness of the disk) is variable and increases towards the disk center. In known from the prior art moldings with electrically conductive carbon particles, the resistance remains almost constant.

The measurement of the surface resistance was as shown in Fig. 2.

On the manufactured using the injection molding technique circular specimen 1 with a diameter of 80 mm and a thickness of 2 mm two Leitsilberstreifen 2, 3 are applied, whose length B coincides with their distance L, so that a square area sq (Square) is measured , Subsequently, the electrodes of a resistance measuring device 4 are pressed onto the conductive silver strips 2, 3 and the resistance value is read off on the measuring device 4. For measuring voltages up to 3xlO ⁷ ohms / sq 9 volts were used for resistors and from 3xlO ⁷ ohms / sq 100 volts.

To measure the surface resistance over the specimen thickness of the specimen 1 was ground plane-parallel to the surface by a = 0.04 mm or a = 0.5 mm, the two Leitsilberstreifen 2, 3 each applied again and as described above, the resistance measured.

Example 1 (comparative example)

There are round plates with 80 mm diameter and 2 mm thickness of a composite material of polycarbonate (PC) (commercial product: Makrolon ^® 2805, manufacturer Bayer Material Science AG) with 5 wt .-% carbon nanotubes (German patent application with the official Reference 102007044031.8, manufacturer Bayer MaterialScience AG) produced by injection molding on an injection molding machine from Arburg (type: Allrounder 370 S 800-150, clamping force 800 kN).

At the injection-molded round plates, the electrical surface resistance is then measured as shown in Fig. 2.

The injection molding parameters and measured surface resistances are shown in Table 2 below.

Injection speed refers to the feed rate of the injection molding screw. The set injection speed is only the screw speed and not the effective mass velocity in the runner or in the cavity. An injection rate of 40 mm / s corresponds to a value commonly used for the produced round plate geometry. Back pressure refers to the pressure of the hydraulic system, which counteracts the metering of the granulate behind the screw. The back pressure is measured by means of a pressure sensor in the hydraulics.

, SchneckendrehzahF denotes the speed of the injection screw. 'Melt temperature' refers to the temperature of the carbon nanotube polymer composite melt. It is measured at the end of the injection screw in front of the runner by means of a built-in injection molding cylinder thermocouple.

'Tool temperature' refers to the temperature of the injection molding cavity. It is measured on the inner wall of the cavity by means of a thermocouple.

Table 2

Vers -No Single-point screw worm Mass tool distance a to the surface resistance speed k -speed temperature temperature mold surface surface area mm / s bar l / min ⁰ C ⁰ C mm Ohm / sq

1 (PC382 1-40 150 150 300 90 0 2.69 × 10 ⁶

1) 2

(PC382 1-40 150 150 300 90 0.04 1.44 x 10 ⁷

2) 3

(PC382 1-40 150 150 300 90 0.5 9.5 x 10 ⁶

3) It can be seen that in tests 1 to 3 (standard injection speed, mass and tool temperature in the range of the recommendation from Table 1) the surface resistance is almost constant over the molded part thickness.

Example 2 (Method according to the invention)

There are round plates with 80 mm diameter and 2 mm thickness of a composite material of polycarbonate (PC) (commercial product: Makrolon ^® 2805, manufacturer Bayer MaterialScience AG) with 5 wt .-% carbon nanotubes (German patent application with the official file number 102007044031.8, manufacturer Bayer MaterialScience AG) produced by injection molding on an injection molding machine from Arburg (type: Allrounder 370 S 800-150, clamping force 800 kN).

The injection molding parameters and measured surface resistances are shown in Table 3 below.

Injection speed refers to the feed rate of the injection molding screw. The set injection speed is only the screw speed and not the effective mass velocity in the runner or in the cavity. As a minimum injection speed, a value of 10 mm / s was determined as follows. In a series of experiments, the injection rate was reduced successively at constant other process parameters until the injection mold was no longer completely filled. The injection speed, at which the mold could just be filled, thus represents the minimum injection speed. The minimum injection speed depends in principle on the geometry of the injection molding cavity and the viscosity of the melt. Back pressure refers to the pressure of the hydraulic system, which counteracts the metering of the granulate behind the screw. The back pressure is measured by means of a pressure sensor in the hydraulics.

'Screw speed' refers to the speed of the injection screw. 'Melt temperature' refers to the temperature of the carbon nanotube polymer compound melt. It is measured at the end of the injection screw in front of the runner by means of a built-in injection molding cylinder thermocouple. 'Tool temperature' refers to the temperature of the injection molding cavity. It is measured on the inner wall of the cavity by means of a thermocouple.

Table 3

Vers -No Single-point screw wormMass tool distance a to the surface resistivity temp. Temp. Temperature Shaped body surface dtre mm / s bar l / min ⁰ C ⁰ C mm Ohm / sq

4 (PC382 8-10 150 150 340 120 0 4.49 x 10 ³

D 5

(PC382 8-10 150 150 340 120 0.04 1.45 x 10 ⁴

2) 6

(PC382 8-10 10 150 150 340 120 0.5 1.2 x 10 ⁹

3)

It can be seen that in test 4 to 5 (lowest possible injection speed, material temperature 20 ⁰ C above the recommended in Table 1 range, and mold temperature at the upper limit of the recommended in Table 1 range) increases, the surface resistance of the molding surface for molding middle significantly ,

Claims

claims

1. Electrically conductive molded body made of a thermoplastic carbon nanoparticle polymer composite material, characterized in that the molded body is made by injection molding of thermoplastic polymers and Kohienstoffnanoteilchen and has a gradient of electrical conductivity, such that the electrical conductivity at the surface is high and perpendicular to the surface decreases to a minimum, which is at least 0.1 millimeters below the surface and at most in the middle of the material.

2. Electrically conductive molded body made of a thermoplastic carbon nanoparticle polymer composite material, characterized in that the molded body is produced by injection molding of thermoplastic polymers and Kohienstoffnanoteilchen and has a gradient of electrical conductivity, such that the electrical conductivity at the surface is high and perpendicular to the surface decreases to one

Minimum, which is at least 0.1 millimeters below the surface and at most in the middle of the material and a smaller by a factor of 100, preferably by a factor of 1000 lower electrical conductivity than the electrical conductivity at the surface.

3. Electrically conductive molded body made of a thermoplastic carbon nanoparticle polymer composite material, characterized in that the molded body is produced by injection molding of thermoplastic polymers and Kohienstoffnanoteilchen and has a gradient of electrical conductivity, such that the electrical conductivity at the surface is high and perpendicular to the surface decreases to one

Minimum with a gradient corresponding to a decrease of the electrical conductivity by 2 toe powers per millimeter, preferably of 3 tens of thousands per millimeter.

4. molded body according to claim 1, characterized in that the thermoplastic polymer is selected from the series: polycarbonate (PC), polyamide (PA), in particular polyamide 6, 66 or 12 (PA 6, PA 66, PA 12), polystyrene ( PS), poly (styrene-acrylonitrile) (SAN), acrylonitrile-butadiene-styrene block copolymers (ABS), polyacrylate, in particular polymethyl (meth) acrylate (PMMA), poly (oxymethylene) POM, polyvinyl chloride (PVC), polyesters, in particular polyethylene terephthalate (PET), polybutylene terephthalate (PBT),

Polyalkylenes, in particular polyethylene (PE) and polypropylene (PP), polyetheretherketone (PEEK), polyphenylene ether (PPE), polyphenylene sulfide (PPS), polyurethane (TPU) or blends thereof containing at least two of the enumerated polymers, especially blends of polycarbonate (PC) with ABS or PBT and blends of polyphenylene ether (PPE) and PA ,

5. Shaped body according to claim 1 to 4, characterized in that the carbon nanoparticles are graphite-like nanoparticles.

6. Shaped body according to one of claims 1 to 5, characterized in that the carbon nanoparticles are single or multilayer graphite structures.

7. Shaped body according to one of claims 1 to 6, characterized in that it is the single or multilayer graphite structures to graphene or carbon nanotubes or mixtures thereof.

8. Shaped body according to one of claims 1 to 7, characterized in that the carbon nanoparticles are one or more-walled, in particular multi-walled carbon nanotubes.

9. Shaped body according to one of claims 1 to 8, characterized in that the carbon nanoparticles have a diameter in the range of 1 to 500 nm, preferably a diameter in the range of 3 to 100 nm and more preferably have a diameter of 5-50 nm.

10. Shaped body according to one of claims 1 to 9, characterized in that the carbon nanoparticles in a proportion of 0.2 to 15 wt .-%, preferably from 0.5 to 10 wt .-%, particularly preferably from 1 to 7 wt .-% based on the mass of the molding present.

11. A process for the production of electrically conductive moldings, in particular a molding, by injection molding of thermoplastic polymers and carbon nanoparticles, wherein the moldings have a gradient of electrical resistance perpendicular to the surface in a near-surface layer, such that the electrical resistance increases perpendicular to the surface, in particular in a near-surface layer which corresponds to a quarter of the wall thickness at the location of the shaped body with the smallest wall thickness, characterized in that a) initially to fill the cavity of a mold, the just sufficient minimum injection speed is determined such that in a series of experiments, the injection rate is lowered at constant other process parameters successively until the injection mold is no longer completely filled and the minimum injection speed at which the shape is just could still be filled, ultimately being discontinued

c) the mold temperature of the mold is adjusted by injection molding based on the polymer or polymer mixture used below the glass transition temperature (amorphous thermoplastics) or below the melting temperature (in semi-crystalline thermoplastics), so that the molding can be removed from the mold just without delay.

12. The method according to claim 11, characterized in that the melt temperature b) in the range between the lowered by 20 ⁰ C and increased by 100 ⁰ C maximum temperature of reproduced in the following Table 1 for selected polymers temperature T _mass . _{max is} set. Table 1:

13, Method according to claim 11, characterized in that the tool temperature of the mold according to c) in the temperature range T _{tool min} to a maximum of 20 ° above the reproduced in Table 1 for selected polymers recommended tool temperature T _We rkze _u g- _max »is set.

14. Use of the method according to claim 12 or 13 for the production of electrically conductive housings, e.g. for household and electrical appliances or for components of motor vehicles.