US Patent Application for ADDITIVES AND/OR ADDITIVE-ADDITIVE COMBINATIONS FOR COMPOUNDING, THERMOPLASTIC PLASTIC COMPRISING SAME AND USE OF THE PLASTIC Patent Application (Application #20240191055 issued June 13, 2024) (2024)

The present invention relates to additives and/or additive-additive combinations for compounding in a preferably thermosoft plastic in order to impart EMC shielding properties to the plastic, wherein according to the invention not only the electric field but also the magnetic field is shielded, particularly both electric fields and magnetic fields similarly greater than 20 dB. The present invention similarly relates to a thermosoft plastic in which such additives and/or additive-additive combinations are compounded. The invention further relates to the use of such a thermosoft plastic, particularly for producing objects detectable by X-rays.

Electronic devices and apparatus typically must be designed to be electromagnetically compatible, so as not to interfere with other devices due to undesired electric or electromagnetic effects or to be interfered with by the same. Primary frequencies to be shielded against are thereby between 30 kHz and approximately 5 GHZ, wherein said range is generally referred to as high-frequency radiation. Said frequencies occur in the fields of broadcast radio; television; aircraft, ship, and police radios; GPS; UMTS; Bluetooth; and WiFi- and therefore also in mobile phones and smartphones—as well as in radar measurements and in non-destructive material testing. Said electromagnetic compatibility is often achieved by means of a housing for shielding electromagnetic interference (EMI), also particularly by a plastic housing, and thereby serves both for protecting the devices and apparatus themselves against external radiation and for protecting the surrounding area thereof against electromagnetic radiation emitted by the same.

The shielding or damping of the electromagnetic radiation is, in general, particularly difficult to implement in the magnetic field. For example, it is known in the automotive sector to use metal housings or plastic housings coated with metals in order to provide electronic components with EMI shielding. Said housings, however, are heavy and have at least disadvantages with respect to design freedom relative to plastic, making said housings not suitable for every installation situation. Metal coatings for EMI shielding are made by pressure die-casting aluminum, for example, or by PVD coating the component to be shielded, or by painting with paints comprising metal.

In general, the level of shielding achieved also depends on the wall thickness of the housing or the cladding of the device or component to be shielded, and on the wavelength range of the frequency to be shielded.

For achieving EMI shielding in plastics, it is known from the prior art, among other things, that the following materials are compounded in the following plastic matrices:

- dolomite in PA or PE and granite in a styrene copolymer (EP 1 127 917 B1),
- bronze or brass in PA or in a combination of PC and ABS (KR 2002 068 248 A),
- steel fibers or steel fibers having an Ni—Cu coating,
- CuO, CuCl₂, Cu(OH)₂in PA (WO 2014 163 242 A1),
- magnetite in PA (DE 100 08 473 A1),
- silver-coated glass fibers or beads, carbon nanotubes disposed concentrically in each other (multiwall carbon nano tubes, MWCNT)—also having metal coating—(DE 10 2017 200 448 A1), and
- SiC in PC and ABS (WO 2009 083 914 A1).

Said components, referred to in summary as fillers, are referred to below itemized as electrically conductive additives and as magnetic additives, wherein an electrically conductive additive has a volume resistance of less than 104 Ohm and a magnetic additive has magnetic properties.

The EMI shielding is thereby measured in an electric field based on the standards ASTM D 4935 and IEC 62153-4-4Ed2. The latter standard describes measuring the damping in the electric field in the frequency range from 30 to 3,000 MHz, and the former in the range from 30 to 1,500 MHz. The sample to be measured in the electric and magnetic field is disposed in a shielded chamber between a transmitting antenna and a receiving antenna and the electromagnetic radiation passing through the component is measured in both fields.

The object of the invention is to disclose compounds having improved shielding effect in the electric and in the magnetic field, preferably >20 dB, and thus being particularly effectively usable for EMI applications. Shielding of 20 dB corresponds to shielding of approximately 99% of electromagnetic radiation. Said level of shielding thereby relates to wall thicknesses of between 1 mm and 4 mm, preferably 2 mm, as said thicknesses include most objects made of the compounds according to the invention.

According to the invention, it was completely surprisingly found that a synergy arises from the combination of electrically conductive additives and magnetic additives in particular compounds, leading to an increase in shielding effect in the magnetic field beyond that of simple addition of the shielding effects of each additive. Surprisingly, and only in particular cases, the combination of a magnetic additive and an electrically conductive additive in a particular plastic increases the shielding effect thereof against magnetic fields and thus increases the shielding of the plastic equipped accordingly against magnetic fields. As the applicant was also able to determine, the magnetic additives found according to the invention particularly disproportionately shield not only the electric field but also the magnetic field as a function of the type of magnetism of each, and especially of the particle size thereof (D50 value), as well as in combination with electrically conductive additives, when compounded in one of the thermosoft plastics according to the invention. The applicant surprisingly determined that the combination of two magnetic additives also leads to synergistically increased shielding in the magnetic field beyond that of simple addition.

The invention greatly advantageously enables the use of compounds having corresponding, easily commercially available additives added thereto, referred to in summary as fillers, particularly as fillers for the plastic matrix, in order to surprisingly achieve particularly high magnetic shielding in a simple manner. Plastic housings produced from compounds according to the invention have the advantage, in comparison with metal housings or metal-coated housings, of having reduced weight, as is of great significance particularly for use in e-mobility. In addition, said compounds provide a high degree of freedom for the physical design of the shape of the components produced therefrom and thus high adaptability to a wide range of installation and use conditions.

The plastics suitable for use according to the invention due to the inner structure thereof and the physical and chemical properties thereof include particularly amorphous plastics such as PC, ABS, and PC-ABS combinations, and/or partially crystalline plastics, preferably PA, PA6, PA66, and PA610, but also PPS. Base plastics not optimized for an EMI application can thus greatly advantageously be used for compounding the filler according to the invention, and can be enhanced for the EMI application by means of compounding said additives, so that superlatively EMI-shielded components can be produced from the plastics according to the invention.

The additive combinations according to the invention include carbon fibers (CF) combined with magnetic additives.

According to the invention, a single ferromagnetic additive-particularly 325 mesh powdered iron— can also improve the magnetic shielding at an extremely high and technically not easily achievable weight proportion of 70-80 wt % of the entire compound of filler and base plastic or plastic matrix.

In a further embodiment of the invention, a synergy of the combination of an electrically conductive additive and a magnetic additive was able to be achieved for the following combinations:

- 15% CF+40% natural magnetite, particle density 5.2 g/cm³, ≥98.1% magnetite content, D50=17 μm in PC+ABS
- 15% CF+60% 325 mesh powdered iron in PA6.

For said combinations, a higher shielding in the magnetic field was surprisingly achieved than for each individual additive.

Also surprising is the high shielding effect according to the invention-particularly for the magnetic field for PPS to which 80% ferromagnetic 325 mesh powdered iron has been added.

The same applies for the polyamide PA66 having a 1:1 admixture of paramagnetic aluminum silicate and ferrimagnetic ferroaluminoceladonite, the latter being a special type of mica. Shielding of up to >25 dB in the magnetic field was achieved by means of said filler combination.

PPS and PA66 also achieve a surprisingly high EMI shielding behavior at the admixture indicated above of additives according to the invention.

According to the invention, compounding of 80% and 70% respectively of ferromagnetic 325 mesh powdered iron in PC+ABS and PA6 also achieved shielding values in both fields of >>20 dB (and of >20 dB for 70%). It is thereby particularly preferable according to the invention if powdered iron having a particle size of D50≤ 45 μm is compounded.

According to the invention, the compounding of 5% Ag—Cu-20 (D50: 8-13 μm, diamagnetic flaky copper particles having 20% diamagnetic silver coating) and 33.33% Plasticyl PC1501 (5% pure diamagnetic MWCNT content) in PC+ABS also leads to a synergistic effect of the MWCNTs on the magnetic field of the flaky copper particles Ag—Cu-20, having an increased shielding effect against the magnetic field in comparison with the individual additives. Said material is known from DE 10 2017 209 357.9, the content thereof hereby being explicitly incorporated by reference in the disclosure content of the present patent application.

All other combinations according to the invention of electrically conductive additives and magnetic additives led to shielding in the electric and magnetic field of greater than 20 dB in each case—that is, EMI shielding—but no synergistic increase in shielding of the magnetic field was evident. In other words, the values of shielding against the electric field correspond to the shielding effect of the electrically conductive additive and the values of shielding against the magnetic field correspond to the shielding effect of the magnetic additive.

The applicant has found that the D50 value relating to the particle diameter of the magnetic additive to be used is a deciding parameter for the suitability thereof for synergistic shielding. Therefore, the D50 value of the magnetic additive is specifically selected according to the invention for influencing the shielding effect in the magnetic field in order to cause said additive to be according to the invention.

In a further advantageous embodiment of the invention, PA and PPS are each used as the matrix plastic to which the additives are added as fillers. Here the combined addition of carbon fibers and magnetite has been found to be particularly effective at shielding according to the invention.

In PA as the plastic, the combined addition of carbon fibers and powdered iron and/or of carbon fibers and magnetite has been found to be particularly effective at shielding according to the invention. In PPS as the matrix plastic, an addition of 80% and 70% of ferromagnetic 325 mesh powdered iron without adding carbon fibers is according to the invention, whereas the combination of carbon fibers and gas-atomized ferritic powdered steel is surprisingly not particularly effective at shielding.

In this context, it is particularly advantageous if the additives having a D50 value≤45 μm are used for PA6 as the plastic.

The magnetic additives suitable according to the invention come from the range of diamagnets, paramagnets, ferro- and ferrimagnets having high magnetic susceptibility (χ 500-3,000), up to partially very high magnetic susceptibility (×10,000-50,000). Particularly the following magnetic additives can be considered in the context of the invention, wherein the value of the magnetic susceptibility χ is indicated after the magnetic additive in each case:

Type of magnetism Superparamagnetic Ferromagnetic Potential Nanomagnetite Hematite/maghemite Indium, indium oxide (biocompatible) (χ = 760-50,000) Nanohematite Iron Titanium boride (biocompatible) (χ = 50,000) Copper(II) oxide Pyrrhotite Brass nanocrystals (χ = 69,000) Peridotite Gadolinium Bronze (χ = 6,600) Copper-nickel Gallium phosphide (constantan) Silicon carbide/fiber nano-silicon carbide Cu(I) oxide Phosphate flame retardant

Paramagnetic Manganese bismutite Dolomite Siderite Granulite (χ = 41) (χ = 270) (χ = 1,000) Copper(II) oxide Ilmenite Nickel sulfate Granite acetate/hydroxide/ (χ = 80) (χ = 416) (χ = 1,900) chloride Gallium arsenide Fayalite Wolframite/ Manganese (intrinsic (χ = 130) tungsten sulfate semiconductor) (χ = 2,640) Gallium chloride Quartzite Jacobsite Serpentinite (semiconductor) (χ = 170) (χ = 500) (χ = 2,900) Aluminum (χ 22) Copper Serpentine sulfate (χ = 630) (χ = 176)

A thermosoft plastic according to the invention having compounded filler in the form of a magnetic additive and/or having compounded filler in the form of a combination of magnetic additive and electrically conductive additive is advantageously suitable and usable for achieving X-ray detectability of products made therefrom.

The following magnetic additives are particularly suitable in the context of the invention, the admixture proportion, optionally the preferred admixture proportion, the D50 value thereof, and the type of magnetism thereof being indicated for each:

1) Manganese sulfate 15-25% D50: n.a., paramagnetic 2) CuSn10 having indeterminate particle shape 0-25% D50: 64.4 μm, diamagnetic copper alloy 3) CuZn30 having indeterminate particle shape 0-25% D50: 240 mesh, diamagnetic copper alloy 4) Copper(II) oxide 0-50%, preferably 15-45% D50: 23.9 μm, diamagnetic ceramic and semiconductor 5) 325 mesh powdered iron 15-85%, preferably 55-85% D50: ≤45μm, ferromagnetic 6) gas-atomized ferritic powdered steel 15-85%, preferably 55-85% D50: 20-53 μm, ferrimagnetic 7) natural magnetite (iron oxide/iron ore) 15-65% particle density 5.2 g/cm³, ≥98.1% magnetite content D50: 17 μm, ferrimagnetic 8) aluminum oxide (aluminum ceramic) 65-75%, Al2O₃ content >99.5%, D50: 1.6 μm, paramagnetic 9) anhydrous aluminum silicate treated with aminosilane (aluminum ore), 35-45% Al2O3 content 42.1-44.3%, SiO2 content 51.0-52.4%, TiO2 content 1.56-2.5% D50: 1.4 μm, paramagnetic 10) dolomite (calcium magnesium ore) 35-45% D50: 2.4-3.0 μm, whiteness Ry ≥93.5% paramagnetic 11) aluminum silicate + ferroaluminoceladonite (iron ore) each 10-20%; see above + MICA, D50: 4.2 μm, ferrimagnetic 12) Ag—Cu-20 (flaky copper particles with 20% silvercoating) 5-10%, D50: 8-13 μm, diamagnetic + PlasticylPC1501 (2-5% pure diamagnetic MWCNT portion) 13.33-33.33%

The following combinations of magnetic additives and electrically conductive additives are particularly well suited in the context of the invention, wherein the electrically conductive additive in each case is carbon fiber at a weight proportion between 10 wt % and 20 wt %, and the magnetic additive is:

- magnetite at a weight proportion between 35 wt % and 65 wt %, a particle density of 5.2 g/cm3, a magnetite content of ≥98.1% and a D50 value of 17 μm, or
- 325 mesh powdered iron at a weight proportion between 55 wt % and 65 wt % and a D50 value of ≤45 μm, or
- gas-atomized ferritic powdered steel at a weight proportion between 55 wt % and 65 wt %, a D50 value of 20-60 μm, or
- manganese zinc ferrite at a weight proportion between 35 wt % and 65 wt % and a D50 value of 250-315 μm.

In the context of the invention, the particle size of the magnetic additives and/or electrically conductive additives, indicated as the D50 value, is preferably 10-60 μm and/or 250-315 μm for ferrimagnetic additives, ≤45 μm for ferromagnetic additives, in order to achieve ideal shielding of the magnetic field and <3 μm for paramagnetic additives in order to achieve ideal shielding of the magnetic field. Aluminum oxide, dolomite, aluminum silicate, ferroaluminoceladonite are particularly selected in said size range according to the invention. The size of the particles of the paramagnetic additives according to the invention is alternatively 10-20 μm.

For diamagnetic additives, ideal shielding behavior in the magnetic field can be achieved in the context of the invention at a D50 value of 8-13 μm (D50 value of Ag—Cu-20, 20% silver coating on flaky copper particles) in combination with multi-walled carbon nanotubes (MWCNT).

For further diamagnetic additives in combination with carbon fibers in the context of the invention, the particle size is preferably in the interval between 8-13 μm in order to achieve optimum shielding in both fields.

According to the invention, the particle size of the magnetic additives in general is selected in the interval from 10-60 μm in order to achieve particularly high shielding in the magnetic field and simultaneously very good distribution of the additives in the plastic matrix.

As has been shown by the embodiment examples listed below in tabular form in Table 2a, the use of other particle sizes did not lead to the synergy according to the invention.

The components produced from the plastics for which the EMI measurement was performed have a component thickness between 1 mm and 4 mm, preferably between 2 mm and 3 mm.

The plastics according to the invention can be used advantageously in order to make objects made thereof or coated with the same suitable for X-ray detection. The objects produced from or coated with the plastics according to the invention are thus advantageously detectable by means of a portable X-ray device or by means of a conventional X-ray device in medical practices.

For the present use according to the invention for detectability by means of X-ray radiation, the following magnetic additives are preferred:

- 1) CuSn10 having indeterminate particle shape at a D50 value of 64.4 μm at or above a weight proportion of 20 wt %,
- 2) 240 mesh CuZn30 having indeterminate particle shape, at or above a weight proportion of 20 wt %,
- 3) copper(II) oxide at a D50 value of 23.9 μm, at or above a weight proportion of 20 wt %,
- 4) natural magnetite having a particle density of 5.2 g/cm3, a magnetite content of ≥ 98.1%, a D50 value of 17 μm, at a weight proportion between 20 wt % and 40 wt %,
- 5) 325 mesh powdered iron at a weight proportion between 20 wt % and 40 wt %.
- 6) gas-atomized ferritic powdered steel at a weight proportion between 55 wt % and 80 wt % and a D50 value of 20-53 μm.

EMBODIMENT EXAMPLES

The invention is described below in tables using preferred embodiment examples. Material compositions of the plastics used as the base matrix and the compounded magnetic additives and electrically conductive additives are thereby listed in the tables, and advantageous properties of each composition are listed in each case.

Each of the embodiment examples listed in the table below comprises the base or matrix plastic used, the type of filler or the additive mixture, the D50 value of the particle size, and the weight proportions of the compounded magnetic additives and electrically conductive additives, as well as the proportions of each. Sample objects having a wall thickness of 2 mm were produced from said compounds made of matrix plastic and filler. Measuring the shielding against the electric and against the magnetic field was fundamentally performed on said 2 mm thick sample objects made of the corresponding plastics, as said thickness is closest to the majority of frequently typical housing applications. Said testing further takes place near the sample.

Base Recipes

Base recipe 1 is a PC-ABS having a weight of 100,600 g.

Base recipe 1 Weight [g] High-impact ABS 48,000 Low-viscosity PC 52,000 Lubricant 200 Processing aids 400

Base recipe 2 is also a PC-ABS having a weight of 100,100 g, wherein lubricant is already present in the matrix plastic:

Base recipe 2 Weight [g] PC-ABS 65:35 100,000 Antioxidant 100

Base recipe 3 is a PA6 having a weight of 101,800 g and the following composition:

Base recipe 3 Weight [g] PA6 Type A (2.4 = NV) 100,000 Lubricant 800 Antioxidant 1,000

Base recipe 4 is a PA66 having the following composition; base recipe 4a is a PA66 having a weight of 102,000 g; and base recipe 4b is a PA66 having a weight of 104,242 g:

Base recipe 4 Proportion PA66 TYPE A (2.9 = MV) 22.9% Antioxidant 0.5% Lubricant 0.3% Weight [g] Base recipe 4a PA66 Type A (2.9 = MV) 100,000 Lubricant 300 Antioxidant 500 Lamp black batch (50%) 1,200 Base recipe 4b PA66 Type A (2.9 = MV) 70,000 PA6 30,000 Lubricant 300 Antioxidant 1,800 Colorant 2,142

Base recipe 5 is a PA6 having the following composition:

Base recipe 5 Proportion PA6 Type A (2.9 = MV) 54.7% Antioxidant 0.5% Lubricant 0.3% Colorant 1.0%

Base recipes 6 and 6a are each a PA6:

Weight [g] Base recipe 6 PA6 Type A (2.4 = NV) 100,000 Inherent filler 20,760 Lubricant 500 Antioxidant 500 Colorant 2,800 Base recipe 6a PA6 Type A (2.4 = NV) 100,000 Lubricant 500 Antioxidant 500 Colorant 2,800

Base recipe 7 is a PPS having a weight of 100,900 g; base recipe 7a is a PPS having a weight of 101,896 g:

Weight [g] Base recipe 7 PPS (VISKO 50) 100,000 Lubricant 600 Colorant 300 Base recipe 7a PPS 100,000 Lubricant 610 Colorant 1,286

The magnetic and electrically conductive additives used are particularly the following:

Magnetite has the composition Fe3O₄═Fe(II)Fe(III)2O4 and a spinel structure and ferrimagnetic behavior.

Powdered iron is ferromagnetic.

MnZn ferrite has the composition MnaZn(1−a)Fe2O4.

Powdered steel is a gas-atomized ferritic powder having 20-53 μm particle size and is ferrimagnetic.

Plasticyl PC1501 is a 15% MWCNT; CuSn10 is a diamagnetic, silver-coated copper.

Ultrafine aluminum oxide Al₂O₃is paramagnetic; aluminum silicate Al₂O₃SiO₂is paramagnetic.

Mica is a ferrimagnetic ferroaluminoceladonite K Al(Mg, Fe) [Si₄O₁₀(OH)₂].

Dolomite CaMg(CO₃)₂is paramagnetic.

AgCu20 is diamagnetic, flaky copper particles having 20% silver coating and a D50 value of 8-13 μm.

Carbon fabric is a preform made of industrial waste having a networked structure.

Manganese sulfate MnSO₄is paramagnetic.

Copper(II) oxide CuO having a D50 value of 23.9 μm is a diamagnetic ceramic and a semiconductor.

TABLE 1 Base recipe 1, magnetic additive 2 1 Bronze 3 4 MnSO₄ (CuSn10) Cu(II)O Cu(II)O Weight [g] 25150 25150 25150 67065 Mixture proportion 20 20 20 40 [%] Shielding [dB] H-50 MHz 17.05 16.79 14.15 15.86 H 500 MHz 16.70 16.53 15.87 15.98 H 1000 MHz 21.19 21.34 23.44 20.31 E 50 MHz 13.45 14.04 13.28 12.17 E 500 MHz 12.46 13.44 12.77 11.82 E 1000 MHz 12.09 17.80 21.98 33.59 Surface resistance - n.d. 3.0E12 4.0E+09 2.0E+14 ring electrode [ohm] Specific volume n.d. n.d. 7.0E+14 n.d. resistance [ohm*cm] Residue on ignition [%] 18.0 35.0 30.4 48.7 X-ray detection on 1 cm limited yes yes yes thick pork Particle size D50 n.a 64.4 23.9 23.9 [μm]

TABLE 2 Base recipe 1, electrically conductive additive and magnetic additive 5 6 7 8 9 10 CF + CF + SF + Powdered Powdered Powdered magnetite magnetite magnetite iron iron iron Weight [g] 20120 + 80480 33533 + 89422 28733 + 86222 25150 67067 150900 Mixture proportion [%] 10 + 40 15 + 40 10 + 40 20 40 60 Shielding [dB] H-50 MHz 14.26 15.60 15.31 15.02 15.76 16.02 H 500 MHz 14.67 16.76 14.76 14.59 14.53 15.03 H 1000 MHz 18.44 21.68 16.69 17.31 15.70 20.37 H 1500 MHz 20.01 26.69 18.23 18.57 18.58 18.09 H 2000 MHz 29.88 32.54 18.87 18.43 17.47 17.35 H 2500 MHz 27.59 41.22 20.20 20.70 21.83 20.71 H 3000 MHz 33.47 45.77 22.31 23.52 24.32 23.31 E 50 MHz 33.67 26.60 21.86 15.34 14.59 12.73 E 500 MHz 43.12 43.91 23.54 14.80 14.46 13.61 E 1000 MHz 39.06 43.92 32.23 17.09 16.86 22.67 E 1500 MHz 35.45 40.34 17.20 12.11 11.73 10.51 E 2000 MHz 36.4 44.00 19.18 11.57 11.19 10.51 E 2500 MHz 47.51 55.64 17.11 11.70 11.86 10.68 E 3000 MHz 46.42 53.39 15.89 13.66 11.66 10.40 Surface resistance- 16 10 430 1.0E+12 1.0E+12 8.0E+12 ring electrode [ohm] Specific volume 24192 1586 102000 2.0E+14 4.0E+14 6.0E+14 resistance [ohm*cm] Residue on ignition 40.4 40.7 53.7 27.3 55.0 77.7 [%] X-ray detection on 1 yes — yes limited yes — cm thick pork Particle size D50 [μm] 10-20 10-20 10-20 <45 <45 <45 Where: CF = carbon fiber 7 μm, 6 mm length, SF = steel fiber (75%) 11 μm, 5 mm length, 325 mesh powdered iron

TABLE 2a Base recipes and additive(s), not according to the invention: Base Base Base recipe 1 recipe 1 recipe 7 6a 15a 30 CF + CF + MnZn Powdered magnetite ferrite steel + CF 5 μm 8 μm 20-53 μm Weight [g] 33533 + 33533 + 241440 + 89422 89422 60360 Mixture proportion 15 + 40 15 + 40 60 + 15 [%] Shielding [dB] H-50 MHz 16.3 17.6 1.8 H 500 MHz 13.4 14.5 5.3 H 1000 MHz 12.7 13.3 4.3 H 1500 MHz 13.0 13.1 6. H 2000 MHz 14.6 12.7 7.8 H 2500 MHz 13.9 11.2 8.0 H 3000 MHz 14.0 8.7 8.9 E 50 MHz 25.7 25.4 14.6 E 500 MHz 39.9 32.3 32.2 E 1000 MHz 37.2 29.8 29.5 E 1500 MHz 34.5 28.3 31.5 E 2000 MHz 37.5 31.8 31.5 E 2500 MHz 47.4 30.1 38.9 E 3000 MHz 45.3 30.3 47.4 Surface resistance - 20 23 3 ring electrode [ohm] Specific volume 1.344 1.408 4 resistance [ohm*cm] Residue on ignition 52.6 50.6 85.7 [%] X-ray detection on 1 cm thick pork Particle size D50 [μm]

TABLE 3 Base recipe 1, electrically conductive additive and magnetic additive 11 12 13 14 15 16 17 Powdered CF + powdered Mag- Mag- CF + MnZn CF + MnZn CF + iron iron netite netite ferrite ferrite magnetite Weight [g] 402400 60360 + 241440 25150 150900 33533 + 89422 60360 + 241440 60360 + 241440 Mixture 80 15 + 60 20 60 15 + 40 15 + 60 15 + 60 proportion [%] Shielding [dB] H-50 MHz 35.7 17.09 17.04 15.17 19.79 20.82 20.31 H 500 MHz 51.7 14.69 16.01 15.22 19.11 19.2 19.22 H 1000 MHz 44.5 19.14 20.62 20.18 20.28 25.88 23.93 H 1500 MHz 39.2 18.02 H 2000 MHz 31.3 21.79 H 2500 MHz 35.6 21.43 H 3000 MHz 24.8 25.03 E 50 MHz 26.4 26.79 14.30 13.99 24.01 21.70 25.52 E 500 MHz 49.1 35.59 14.02 14.82 26.80 23.01 43.25 E 1000 MHz 50.0 37.48 22.64 28.77 30.50 26.51 37.80 E 1500 MHz 47.2 27.14 E 2000 MHz 45.6 29.29 E 2500 MHz 46.8 29.96 E 3000 MHz 49.6 29.17 Surface 3 40 7.0E+13 5.0E+11 141 117 17 resistance-ring electrode [ohm] Specific volume 340 192 5.0E+13 4.0E+09 1572 2386 126 resistance [ohm*cm] Residue on 101.13 80.2 21 61.1 38.9 59.1 51.7 ignition [%] TGA C-fiber/ 12.7 13.4 13.7 12.9 graphite content Particle size D50 <45 <45 10-20 10-20 250-315 250-315 10-20 [μm] Density [g/cm³] 3.425 2.52 1.31 2.09 1.76 2.34 1.98

TABLE 4 Base recipe 2 with electrically conductive additive and magnetic additive 18 AgCu20 + MWCNT Weight [g] 8114 + 54099 Mixture proportion 5 + 33.3 [%] Shielding [dB] H-50 MHz 16.80 H 500 MHz 16.43 H 1000 MHz 23.21 H 1500 MHz H 2000 MHz H 2500 MHz H 3000 MHz E 50 MHz 30.60 E 500 MHz 37.17 E 1000 MHz 33.60 E 1500 MHz E 2000 MHz E 2500 MHz E 3000 MHz Surface resistance - 1667 ring electrode [ohm] Specific volume 14600000 resistance [ohm*cm] Density [g/cm³] 1.219 Residue on ignition 5.4 [%] Particle size D50 8-13 [μm]

TABLE 5 Base recipe 3 with electrically conductive additive and magnetic additive 19 CF + 20 21 powdered Powdered Powdered iron iron iron Weight [g] 61079 + 244315 237533 402400 Mixture proportion 15 + 60 70 80 [%] Shielding [dB] H-50 MHz 16.52 24.97 40.11 H 500 MHz 19.38 24.08 49.05 H 1000 MHz 22.93 23.51 38.22 H 1500 MHz 29.38 21.96 38.31 H 2000 MHz 29.07 25.08 31.84 H 2500 MHz 27.86 19.86 26.72 H 3000 MHz 24.16 21.16 30.81 E 50 MHz 20.07 25.91 25.83 E 500 MHz 36.55 35.84 43.38 E 1000 MHz 35.64 32.93 47.56 E 1500 MHz 34.51 33.61 45.10 E 2000 MHz 36.47 34.84 42.40 E 2500 MHz 37.45 32.65 37.25 E 3000 MHz 45.08 33.73 35.50 Surface resistance - 4 130 18 ring electrode [ohm] Specific volume 384 520 19 resistance [ohm*cm] Residue on ignition [%] 80.2 80.4 91.7 Carbon fiber content [%] — — Particle size D50 <45 <45 <45 [μm] Density [g/cm³] 2.584 2.75 3.46

TABLE 6 Base recipe 4 and base recipe 4a 22 23 24 Base recipe 4 Carbon Base recipe 4a Alμminum Base recipe 4b Alμminμm fabric + silicate silicate + conductive mica carbon black Weight [g] 68,000 Weight [g] 22221 + 22221 Mixture proportion 16 + 60 Mixture 40 Mixture proportion 15 + 15 [%] proportion [%] [%] Shielding [dB] Shielding [dB] Shielding [dB] 17.49 H-50 MHz 21.27 H-50 MHz 19.50 H 500 MHz 19.07 H 500 MHz 21.88 H 500 MHz 19.98 H 1000 MHz 23.93 H 1000 MHz 22.27 H 1000 MHz 25.94 H 1500 MHz H 1500 MHz H 1500 MHz H 2000 MHz H 2000 MHz H 2000 MHz H 2500 MHz H 2500 MHz H 2500 MHz H 3000 MHz H 3000 MHz H 3000 MHz E 50 MHz 27.38 E 50 MHz 15.35 E 50 MHz 15.99 E 500 MHz 42.53 E 500 MHz 15.31 E 500 MHz 15.96 E 1000 MHz 52.19 E 1000 MHz 25.01 E 1000 MHz 25.70 E 1500 MHz E 1500 MHz E 1500 MHz E 2000 MHz E 2000 MHz E 2000 MHz E 2500 MHz E 2500 MHz E 2500 MHz E 3000 MHz E 3000 MHz E 3000 MHz Surface Surface Surface resistance-ring resistance-ring resistance-ring electrode [ohm] electrode [ohm] electrode [ohm] Specific volume Specific volume Specific volume resistance resistance resistance [ohm*cm] [ohm*cm] [ohm*cm] Residue on Residue on 38.3 Residue on 29.9 ignition [%] ignition [%] ignition [%] Particle size D50 1.4 Particle size D50 1.4 Particle size D50 1.4 + 4.2 [μm] [μm] [μm]

TABLE 6 Base recipe 5 with electrically conductive additive 25 Carbon fabric Mixture proportion 43.5 [%] Shielding [dB] H-50 MHz 16.34 H 500 MHz 25.37 H 1000 MHz 34.33 H 1500 MHz H 2000 MHz H 2500 MHz H 3000 MHz E 50 MHz 23.40 E 500 MHz 44.81 E 1000 MHz 42.63 E 1500 MHz E 2000 MHz E 2500 MHz E 3000 MHz Surface resistance - ring electrode [ohm] Specific volume resistance [ohm*cm] Residue on ignition [%] Carbon fiber content [%] Particle size D50 [μm] Density [g/cm³]

TABLE 7 Base recipe 6 with magnetic additive and base recipe 6a with magnetic additive 26 27 Al₂O₃ Al₂O₃ Weight [g] 290640 Weight [g] 242200 Mixture proportion 75 Mixture proportion 70 [%] [%] Shielding [dB] Shielding [dB] H-50 MHz 15.11 H-50 MHz 16.32 H 500 MHz 15.55 H 500 MHz 16.67 H 1000 MHz 20.71 H 1000 MHz 20.27 H 1500 MHz H 1500 MHz H 2000 MHz H 2000 MHz H 2500 MHz H 2500 MHz H 3000 MHz H 3000 MHz E 50 MHz 13.12 E 50 MHz 13.83 E 500 MHz 12.93 E 500 MHz 13.72 E 1000 MHz 17.77 E 1000 MHz 18.33 E 1500 MHz E 1500 MHz E 2000 MHz E 2000 MHz E 2500 MHz E 2500 MHz E 3000 MHz E 3000 MHz Surface resistance - Surface resistance - ring electrode [ohm] ring electrode [ohm] Specific volume Specific volume resistance [ohm*cm] resistance [ohm*cm] Residue on ignition 74.2 Residue on ignition 69.6 [%] [%] Particle size D50 1.6 Particle size D50 1.6 [μm] [μm]

TABLE 8 Base recipe 7 with magnetic additive and base recipe 7a with magnetic additive 28 Powdered 29 iron Dolomite Weight [g] 403,600 Weight [g] 102,000 Mixture proportion 80 Mixture proportion 50 [%] [%] Shielding [dB] Shielding [dB] H-50 MHz 22.90 H-50 MHz 15.29 H 500 MHz 37.97 H 500 MHz 15.26 H 1000 MHz 46.72 H 1000 MHz 20.07 H 1500 MHz H 1500 MHz H 2000 MHz H 2000 MHz H 2500 MHz H 2500 MHz H 3000 MHz H 3000 MHz E 50 MHz 27.82 E 50 MHz 14.94 E 500 MHz 49.55 E 500 MHz 14.62 E 1000 MHz 42.18 E 1000 MHz 18.94 E 1500 MHz E 1500 MHz E 2000 MHz E 2000 MHz E 2500 MHz E 2500 MHz E 3000 MHz E 3000 MHz Surface resistance - Surface resistance - ring electrode [ohm] ring electrode [ohm] Specific volume Specific volume resistance [ohm*cm] resistance [ohm*cm] Residue on ignition 79.1 Residue on ignition 49.4 [%] [%] Particle size D50 <45 Particle size D50 <3 [μm] [μm]

In addition to the embodiment examples according to the invention listed in the tables, Table 2a uses embodiment examples not according to the invention to show the significance of particle size. The comparison between magnetite having a particle size according to the invention and particle size not according to the invention, with parameters otherwise unchanged, and the corresponding comparison to ferrite, show that too small a particle size leads to a reduction in the shielding effect in the magnetic field (H field) and thus to compounds not according to the invention. The table also shows that powdered iron is not simply interchangeable with an iron alloy, but rather that the type of magnetic additive shows a great influence on the shielding behavior.

It is further evident that the shielding in the E field drops when the additive particles are too large, as can be seen particularly in comparing magnetite to MnZn ferrite. This is potentially due to interference in the network of carbon fibers by fibers penetrating due to the size and mass thereof.

It is further evident that there is no correlation between the shielding in the E field and H field and the surface resistance. At nearly identical electrical resistances, the values for shielding in the E field vary greatly.