WO2018133935A1

WO2018133935A1 - Cross-linking of silicone-based insulating layers

Info

Publication number: WO2018133935A1
Application number: PCT/EP2017/051052
Authority: WO
Inventors: Wojciech MOTYL; Klaus BITTERWOLF
Original assignee: Leoni Kabel Gmbh
Priority date: 2017-01-19
Filing date: 2017-01-19
Publication date: 2018-07-26

Abstract

The present invention relates to a method for producing a cable or a cable core, comprising one or more silicone-based insulating layers. The invention also relates to cables or cable cores having a bubble-free, silicone-based insulating layer produced according to said method. In addition, the invention relates to means for carrying out the method.

Description

Crosslinking of insulating layers based on silicone

The present invention relates to a method of manufacturing a cable or cable core having one or more silicone-based insulation layers. Furthermore, the invention relates to cables or cable cores with bubble-free insulating layer based on silicone, prepared by this method. In addition, the invention relates to means for carrying out the method, in particular a microwave system.

State of the art

An electrical cable usually comprises at least one metallic conductor, hereinafter also referred to as "cable core" or "conductor", which is sheathed. A conductor can also consist of several sheathed cable cores, which are combined into units and in turn are sheathed once or several times. As the material for the sheaths, silicone rubber based / silicone based materials can be used, whereby in one cable different sheaths of different materials may be present.

Silicone rubber-based materials are applied uncrosslinked to the substrate, for example on a cable core, and then crosslinked. This crosslinking has hitherto been carried out at high temperatures in infrared (IR) furnaces (see FIG. 1 a). This is particularly disadvantageous, since the Kabelbestandeile existing at the time of networking at these high temperatures

must be stable / resistant. This means that so far no silicone coatings could be applied to heat-sensitive layers (substrate).

In addition, it is known that polysiloxanes poorly absorb microwave radiation. In this regard, US 4,980,384 and EP1655328B1 disclose that microwave radiation is not suitable for heating silicones without additives.

Therefore, the use of dielectric inorganic additives to increase the microwave absorption of the silicone composition is described in US 4,980,384, EP 0945916 A2 and EP 1655328 Bl. DE 198 55 718 A1 describes the crosslinking of silicone rubbers, in particular by condensation crosslinking, by means of microwave radiation for the production of moldings, for example medium and high voltage fittings for plastic power cables. However, the production of silicone insulations for cables is not disclosed, in particular, room temperature-curing silicones are not suitable for the production of cable sheathing. Moreover, the crosslinking times of, for example, 25 minutes required in DE 19855718 (Example 1 of DE 19855718) are not suitable for cable production.

EP1900767 B1 discloses a process for the production of silicone foams using microwave radiation. The synthetic procedure described erfor ^¬ changed the addition of magnetite to the absorption of microwave radiation. In addition, blowing agents are used to produce foams. The production of

Cable sheathing is not suggested.

US 4,460,713 describes the preparation of an elastomeric silicone foam by drying a silicone emulsion by means of microwave radiation.

In view of the above-mentioned problems, therefore, there was a need to provide an improved method for producing silicone sheaths for cables or cable cores.

Summary of the invention

In the context of the present invention, it has been found that silicone-based sheathings for cables or cable cores can be crosslinked by the use of microwave radiation. According to the present invention, a metallic conductor is inserted and / or performed in a microwave chamber. The microwave radiation couples into the conductor, the resulting "microwave field" spreads radially symmetrically and runs along the conductor, so that even different geometries can be fully networked (ie the microwave radiation is guided along the metallic conductor and the conductor serves as a kind Antenna). In the use of microwaves according to the invention, temperatures are not so high that the materials of the cable could outgas.

The present invention relates to a method for producing a cable or a cable core, comprising one or more silicone-based insulation layers, comprising the steps: a) applying an uncured silicone rubber-containing composition containing polysiloxanes which the basic building block Si (R, R ^* included) 0, wherein R and R 'represent inde ^¬ pendently organic substituents, with different Si (R, R') (> Units can be present in a polysiloxane molecule, by means of an extrusion process

i) one or more metallic cable core (s), or

ii) a cable core, or

iii) a plurality of cable cores combined into one unit, wherein the unit may already have one or more insulation layers as a sheathing of the cable cores,

to form an insulating layer, wherein

the silicone rubber-containing composition contains no dielectric inorganic additives other than silica / silicon oxides; and b) crosslinking the applied silicone rubber-containing mass in a monomode microwave chamber with continuous radiation of 2450 MHz ± 100 MHz while continuously passing the applied silicone rubber-containing mass through the mono-mode microwave chamber, wherein the crosslinking is in accordance with one or more of both of the following take place:

i) addition crosslinking, wherein one or more of R and R 'of a polysiloxane molecule are alkenyl substituents which react with silane groups of oligosiloxanes contained as crosslinking agents in the silicone rubber-containing composition in the presence of catalytically active salts and or metal complex catalysts; and

ii) peroxide crosslinking, where R and / or R 'of different polysiloxane molecules link in the presence of peroxides.

Furthermore, the invention relates to the use of a microwave system comprising

(i) a magnetron for generating an unpulsed, electromagnetic radiation,

(ii) a mono mode microwave chamber with two opposing openings,

(iii) a waveguide connecting the magnetron to the mono-mode microwave chamber, (iv) at least one absorber arrangement on at least one of the openings of the microwave chamber, the absorber arrangement having one or more chambers, and

(v) a system for impedance matching the microwave system,

for the microwave crosslinking of silicone-based insulating layers, preferably for microwave crosslinking according to the method of the invention.

Moreover, the invention relates to a cable or cable core produced by the method according to the invention.

With the method according to the invention, silicone-based insulation layers can be produced on a substructure containing temperature-sensitive materials, for example a cable or cable core covering, for the purpose of a multi-layer construction. So far, it has not been possible to apply a silicone layer to a polyethylene layer or a layer of comparable polyolefin and to crosslink it. In the previously known method of crosslinking insulation ^¬ layers based on silicone used temperatures were too high. With the microwave technique based method of the present invention, lower temperatures may be used so that reflow of the materials already present prior to the application of the silicone layer can be avoided.

In addition, braids of e.g. Aramid (Kevlar) can be coated with silicone bubble-free in higher wall thicknesses. A non-bubble-free coating is possible with known methods only with limited wall thicknesses.

A further advantage of the method according to the invention is that the microwave beams are advantageously coupled into the metallic conductor of the cable, the cable core and / or the sheathing and the crosslinking reaction is accelerated. The inventive method is thus more efficient and faster. In particular, the conductor in the microwave chamber has a positive effect on the heating. If a metallic conductor is introduced into the waveguide, a coaxial structure results. This has the advantage that the microwave is immediately coupled into the metallic part and the resulting "microwave field" propagates radially symmetrically and runs along the conductor. So the microwave does not run into the empty microwave chamber, where it is reflected by the housing, but can be coupled into the center of the line. Here are two effects. On the one hand, the microwave immediately inserts into the metallic conductor and, on the other hand, the microwave passes through the silicone insulation layer. As a result, a larger area is "irradiated". As already described, the microwave irradiation of the uncrosslinked silicone rubber-containing mass is carried out in a microwave chamber, wherein the microwave radiation is generated by a magnetron and irradiated by means of a waveguide. However, the coupling of the microwave radiation in the conductor leads to an unexpected disadvantage, namely that the radiation from the microwave chamber can escape through the conductor into the environment. According to the invention, this radiation is "captured" again by the absorber arrangements and at least partially reflected back into the microwave chamber As is shown in FIGURE 1a, various temperature conditions or a temperature gradient are created in known processes using a plurality of IR ovens, so that the crosslinking initially occurs The absorbers according to the invention make possible a different construction with only one energy source, ie irradiation of the energy exclusively into the microwave chamber The absorbers also increase the safety of the microwave system since they protect the working personnel from radiation.

In addition, using a microwave system results in less energy losses compared to conventional IR ovens that need to be heated to several hundred degrees Celsius, the microwave does not need this preheating, and the process is more environmentally friendly and less expensive. In particular, the use of the microwave system described herein enables very high energy efficiency and production speed. It can also be achieved by omitting previously required long sintering sections space savings. In addition, the microwave radiation used in the invention suffers no power loss in depth. The microwave penetrates completely into the material and heats it evenly. In IR, the heating is through the

Material thickness inhibited in the component.

Detailed description of the invention

The present invention relates to the following embodiments:

A method of making a cable or cable core having one or more silicone-based insulating layers, comprising the steps of: a) applying an uncrosslinked silicone rubber-containing composition comprising polysiloxanes containing the basic building block Si (R, R ') O, wherein R and R 'are independent represent organic substituents, wherein different SiC ^ R ^ O units may be present in a polysiloxane molecule, by means of an extrusion process

i) one or more metallic cable core (s), or

ii) a cable core, or

iii) a plurality of combined into one unit cable cores, the unit may already have one or more insulation layers as a sheath of the cable cores to ^¬,

to form an insulating layer, wherein

The phrase "different SR ^ O moieties may be present" means that R and K of the different Si ^ R ^ O moieties are independently selected Usually, the majority of Si (R, R ') carries 0 moieties In addition, alkenyl substituents, for example vinyl groups, are present, which are usually terminal.

According to the invention, at least one absorber arrangement is arranged on at least one of the openings of the microwave chamber in order to absorb and at least partially reflect the microwave radiation. Since the microwave radiation couples into the conductor, that is to say the metallic cable core, there is a certain power loss without the absorber arrangement according to the invention that radiation exits the microwave chamber, so that at least partially reflecting back the radiation is advantageous.

The implementation of the method is described in more detail below, in particular in the examples. Basically, the starting material, i. the metallic cable core, a cable core, or a plurality of combined into one unit cable cores, which may already be covered, to be wound on a winding device. The starting material is then unwound and, optionally after further treatment, passed to an extruder where it is coated with the uncrosslinked silicone rubber-containing composition.

Subsequently, it is passed through for crosslinking through the microwave chamber, that is, the starting material enters through an opening in the microwave chamber and through an opposite opening back out of the microwave chamber again. After complete or desired curing, the umman ^¬ tete product or intermediate product may optionally be rewound on a winding device. It is of course possible at any point of the process to perform additional, additional process steps, such as the application of release agents against the sticking together of the cable on the winding device (coil).

In one embodiment, therefore, a silicone rubber-based sheath is applied to a cable core or a unit of cable cores, the unit already having one or more sheaths. Even with this multi-layer structure, the coupling of the microwave radiation in the conductor has a positive effect because the radial symmetry of the microwave field is more ^¬ layer structure suitable for irradiation.

The peroxide crosslinking and addition crosslinking according to the invention does not require the presence of atmospheric moisture, as is the case, for example, with LSR silicones crosslinking in room temperature.

2. The method of embodiment 1, wherein one or more of R and R ^{* of} a polysiloxane molecule are alkenyl substituents.

The alkenyl substituents are preferably terminal. The alkenyl groups participate in the crosslinking reaction. 3. The process of embodiment 1 or 2, wherein the uncrosslinked silicone rubber-containing composition comprises:

Contains 50-80 wt .-% polysiloxane molecules in which one or more of R and K are vinyl groups, preferably the polysiloxanes are vinyl group-containing polydimethylsiloxane, and / or

10-40%, preferably 20-40%, or 20-30%, of hydrophobic fumed silica, which is preferably surface-modified.

The silicone-rubber-containing composition particularly preferably contains only polysiloxanes and silicon oxide (s), and optionally crosslinking agents and / or catalysts.

Fumed silica or fumed silica, as it is also called, is made entirely of amorphous silica particles (SiO _2), which are aggregated into larger ^¬ A units. These have a very good dipole moment and are very well activated by microwaves. According to the invention no microwaves ^¬ additive must therefore be added. In addition, the presence of the electrical ^conductor causes the use of energy to be improved.

The uncrosslinked silicone rubber-containing composition may contain 0-15% lower viscosity polydimethylsiloxanes than polysiloxane molecules.

4. The method according to any one of the preceding embodiments, wherein the uncrosslinked silicone rubber-containing composition is high-temperature crosslinking, and preferably at a temperature of above 95 ° C, preferably in a range of 110 ° C to 220 ° C, crosslinkable. The residence time, based on 1 cm Bestrah ^¬ coupling portion, in the inventive method is preferably from 0.012 s to 0.006 s. The production rate is thus preferably between 50 and 100 m per minute.

5. The method according to one of the preceding embodiments, wherein the microwave radiation (generated by a magnetron) is used as the sole energy source. In particular, the method is performed using the microwave system described herein.

6. The method according to any one of the preceding embodiments, wherein the microwave radiation with a power of at least 900 W, preferably 900 W to 6 kW or 900 W to 2500 W, is irradiated. For the crosslinking reaction 900W power in general. However, to achieve the production speed, the performance can be increased.

7. The method according to any one of the preceding embodiments, wherein the molecular weight of the uncrosslinked polysiloxanes is 250,000 to 900,000 g / mol.

8. The method of any one of the preceding embodiments, wherein the uncrosslinked silicone rubber-containing composition is solid (MQ / VMQ) or liquid (LSR) and the degree of polymerization of the uncrosslinked polysiloxanes is preferably 5,000-10,000 for solid silicone rubber and 600-1,800 for liquid silicone rubber. In one embodiment, the uncrosslinked silicone rubber-containing composition is solid (MQ / VMQ), i. it is not LSR.

9. The method according to any one of the preceding embodiments, wherein the radicals R and R 'of the polysiloxanes are independently selected from the group consisting of substituted or unsubstituted Ci-C ₈ alkyl groups and substituted or unsubstituted Ci-Cs-alkenyl groups. Fluorine atoms are not preferred substituents. More preferably, the radicals R and R 'are independently selected from the group consisting of methyl, phenyl, vinyl, and fluorine-modified Ci-C ₅ alkyl groups. The C 1 -C ₈ -alkyl groups and C 1 -C -alkenyl groups are preferably unsubstituted. In one embodiment, the radicals R and R "are therefore independently selected from the group consisting of methyl, phenyl, and vinyl In particular, the silicone rubber-containing composition contains dimethyl-vinylmethyl-siloxane (VMQ) or α, ω-divinylpolydimethylsiloxane more than 80% of the radicals R and R ^{x are} methyl groups and less than 20% are vinyl or phenyl groups, with vinyl groups being present For example, 80% -90% of the radicals R and R 'are methyl groups and 10% -20% are vinyl or phenyl groups Preferably, about 80% of R and R 'are methyl groups and about 20% are vinyl or phenyl groups with vinyl groups present For example, less than 10% or less than 5% phenyl groups are present in the above embodiments. in one embodiment, dimethyl vinyl methyl siloxanes (VMQ) are only present as polysiloxanes in the Sili ^¬ konkautschuk-containing mass. in addition, oligo Siloxanes are present as crosslinkers.

10. The process of any one of the preceding embodiments, wherein the uncrosslinked silicone rubber-containing composition is preferably polydimethylsiloxanes (MQ) and / or copolymers of dimethylsiloxane and vinylmethylsiloxane (VMQ).

11. The process of any one of the preceding embodiments, wherein the addition cure is a two component (2K) platinum catalyzed (hydrosilylation) reaction. Polysiloxanes with vinyl end groups (component A) and Si-H oligosiloxanes (component B, crosslinker), for example a comb-shaped, star-shaped or resinous crosslinker, preferably react here. The catalyst used is preferably a platinum (0) compound, preferably hexachloridoplatinic acid having the formula H ₂ [PtCl ₆ ]. In the addition cross-linking based on Festsili ^¬ konkautschuk the amount of catalyst by weight preferably 0.5 and 1 wt .-%.

12. The method according to any one of the preceding embodiments, wherein a peroxide crosslinking is carried out.

In the peroxide crosslinking reaction by the thermal decomposition of the Per ^¬ oxides is that leads to the formation of two radicals initiated. Subsequently, the radical transfer to the silicone rubber either by substitution of a hydrogen atom of an alkyl substituent, in particular in so-called "non-specific" silicones, ie pure dimethyl siloxanes (MQ) without alkenyl / vinyl groups in the chain, or by addition to the double bond of alkenyl substituents, especially in so-called "vinyl-specific" silicones, ie dimethyl-vinylmethyl-siloxanes (VMQ) contain vinyl groups. Depending on which silicone is present different peroxides can be used. These may be dialkyl, diaryl-alkyl and aromatic diacyl peroxides. Preference is given to using "bis (2,4-dichlorobenzoyl peroxide)" (DCLBP). In the case of VMQ silicones, which are preferred in the present case, non-vinyl-specific peroxides, preferably DCLBP, are used.

13. The method according to any one of the preceding embodiments, wherein the polysiloxanes consist exclusively of Si (R, R ') O units.

14. The method of any one of the preceding embodiments, wherein the silicone rubber-containing composition is based on a one-component silicone rubber, wherein the polysiloxane is either peroxide-crosslinking and the peroxide is mixed, or addition-crosslinking, wherein the crosslinker is already in the polysiloxane is bound and the platinum catalyst is mixed. 15. The method of any one of the preceding embodiments, wherein the silicone rubber-containing composition is based on a two-component silicone rubber, which are addition-crosslinking polysiloxanes in which the platinum catalyst in component A and the crosslinker in component B contained and mixed together just before use.

16. The method according to any one of the preceding embodiments, wherein the silicone rubber-containing mass 5-40 wt .-% Si0 ₂ , for example 5 wt .-% Si0 ₂ , and 5-70%, preferably 20-40%, pyrogenic Si0 ₂ or precipitated silica. The amount of Si0 ₂ can be determined, for example, after ashing of the silicone in a muffle open.

17. The method according to any one of the preceding embodiments, wherein the silicone rubber-containing composition does not contain ferrites, e.g. Magnetite, and / or propellant contains. Propellants are gases or chemical compounds that release gases or water under crosslinking conditions, e.g. Carbonate.

18. The method according to any one of the preceding embodiments, wherein the silicone rubber-containing composition except silicon oxide / silicon oxides, no dielectric, inorganic additives, such as silicon carbide, silicon carbonitride, Kohlenstoffnanotubes; Iron compounds (e.g., iron carbonyls), carbon black, and metal oxides, especially iron oxide or iron oxide-containing metal oxides.

19. The method of any one of the preceding embodiments, wherein the silicone rubber-containing composition contains pigments.

20. The method of any one of the preceding embodiments, wherein at least one or more poly (organo) siloxane insulating layers are present and applied either sequentially or simultaneously.

22. The method according to one of the preceding embodiments, wherein the cable comprises or consists of one or more wires running parallel in the longitudinal direction of the cable.

For the purposes of the present invention, a "wire" is a single, solid metal conductor / strand. A "stranded wire", eg round strand, pointed strand or flat strand, consists of bundled wires. A core or cable core has a metallic cable Core core, which is sheathed with one or more insulating layers. A "cable" contains cores that are stranded together, optionally with fillers or other elements, and are encased in one or more layers. Conductors can be stranded in pairs or triples, the elements can be stranded one or more layers with fillers for gusset filling and form a unity.

For example, PTFE, glass silk, polyamide, polypropylene or cotton filler can be used for gusset filling. Preferably, the wires and strands of copper, or copper, which has a layer support such as tin, nickel or silver on ^¬ has.

Thus, according to the invention, a first insulating layer based on silicone can be applied to the metallic conductor, ie wire / wires or strand / strands. However, it is also possible to apply a subsequent layer, for example a second or third layer, to one or more layers already present on the conductor. Likewise, several combined cable cores can be provided with a silicone-based insulation layer. Either cable cores vers can ^¬ approaches and are optionally provided with further constituents and then surrounded with an insulating layer based on silicone. Alternatively, the unit of several cable cores may already be provided with one or more sheathing (s) and a subsequent layer, eg a second or third layer, is applied to the layer (s) already present on the unit. Of course, after the application of the silicone-based insulation layer, further layers can be applied to the cable core or the cable. It is also possible to apply a second or further silicone-based insulation layer directly to a silicone-based insulation layer or to a layer above the silicone-based insulation layer.

23. The method according to any one of the preceding embodiments, wherein the insulation materials of the stranded cables (the sheathing of stranded wires) can be made of high performance plastics such as fluoropolymers, PEEK, PTFE. According to the invention, for example, the wires can be isolated with silicone, then the wires are stranded and sheathed once again with silicone. The silicone can also be used for the gusset filling to make the cable round. In principle, the silicone can be applied directly to the metal, or via another polymer layer. Thus, the silicone sheath can be used as a core insulation and / or as a sheath material and / or as a filler. 24. The method of any one of the preceding embodiments, wherein the insulating materials underlying the silicon-based insulating layer (directly beneath or with further intermediate layers therebetween) are temperature-sensitive materials such as polyolefins, PVC, and thermoplastic elastomers. Such materials would not survive the introduction of temperature by conventional infrared radiation in the crosslinking of silicones. However, since the process according to the invention makes possible milder conditions, the sensitive layers can be spared.

25. The method according to any one of the preceding embodiments, wherein the substructure may consist of materials or coated, which tend to degas at high temperatures, which may be in the form of bubbles on the silicone insulation. In the use of microwaves according to the invention, temperatures are not so high that the materials could outgas. The term "substructure" refers to the substrate to which the silicone-based insulation layer is applied.

Wires with braid, with silicone being given around. The mesh pulls air moisture and therefore leads to bubble formation in the silicone at the temperature.

26. The method according to any one of the preceding embodiments, wherein the direction of impact (S-beat or Z-beat) and stranding direction in the unilay or in the true concentric can be present.

27. The method according to one of the preceding embodiments, wherein the cable comprises a current-carrying element or signal-carrying element, for example a current-carrying wire or a current-carrying conductor and / or a conductor element and / or signal transmission element.

28. The method of any one of the preceding embodiments, wherein the cable core is made of one wire (s), e.g. Flat wire, a wire bundle, a wire mesh, e.g. Braided hose, or consists of a strand / multiple strands.

29. The method according to one of the preceding embodiments, wherein the cable is an endless cable, or the conductor is an endless conductor, or the cable core is an endless cable core, and preferably has a length of at least 500 meters. 30. The method according to any one of the preceding embodiments, wherein the cable core has a diameter of> 1 mm.

31. The method of any one of the preceding embodiments, wherein the silicone insulating layer is applied directly to the metal-containing cable core, preferably uninsulated, coated or uncoated wires or strands.

The metal in the core of the cable has a positive influence on the crosslinking of the silicone rubber-containing compound. On the one hand, the metallic conductor acts like an antenna. The microwave couples into the ladder. With the housing of the microwave chamber creates a coaxial structure, which means a homogeneous field propagation between the conductor and the microwave chamber.

32. The method according to any one of the preceding embodiments, wherein the silicone insulating layer has a layer thickness of 0.5 mm - 4.0 mm.

The invention also relates to a cable or cable core with a bubble-free silicone insulation layer, which can be produced or manufactured using the method according to one of the preceding embodiments, wherein the wall thickness of the silicone-based insulation layer is preferably from 0.5 mm to 4.0 mm.

The protruding cable or cable core preferably contains a temperature-sensitive sheath / layer, e.g. a sheath / layer of polyolefin, PVC, or thermoplastic elastomers, or polymers having a temperature of <150 ° C.

The invention also relates to a microwave system which can be used for crosslinking the silicone rubber ^{¬-containing} composition according to the inventive method. The microwave system may be configured according to the following embodiments:

Ml. Microwave system comprising

(i) a magnetron for generating a non-pulsed, electromagnetic Strah ^¬ lung,

(ii) a mono mode microwave chamber with two opposing openings, (iii) a waveguide connecting the magnetron to the monomode microwave chamber,

(iv) at least one absorber arrangement on at least one of the openings of the microwave chamber, the absorber arrangement having one or more chambers, preferably 2-8 or 3-6, particularly preferably 3-4, chambers, and

(v) a system for impedance matching the microwave system.

The opposing openings of the mono-mode microwave chamber are designed to pass products in particular with uncrosslinked silicone rubber-containing mass provided cable / cable wires / conductors during the microwave ^¬ warming. In particular, the openings of the microwave chamber and absorber for cables are adapted with a cross section of 0.5 mm ² to 125.0 mm ² . Here, the distance between the cable and the microwave chamber or the absorber is at least 1.0 cm. The chambers of the absorber ^arrangement (hereinafter also the "absorber") are likewise provided with opposing openings so that the products can also be passed through these chambers.The chambers of the absorbers and the mono-mode microwave chamber are arranged in a row. For example, in the manufacture of continuous cable cable coatings, a cable transport system is used that continuously passes the cable product through all of the chambers, including the mono-mode microwave chamber, then further processing steps or the cable product is produced as a finished product.

The number of chambers and the length of the absorber are dependent on the line to be crosslinked and the overall structure of the microwave system. In particular, by increasing the reflection of the radiation by appropriate design of the absorber or by increasing the number of absorber chambers, a higher performance can be achieved on the product to be processed. This is insbesonde ^¬ re important if to be heated part of the product poorly absorbed microwave radiation.

In one embodiment, a silicone rubber-based sheath is applied to a cable core or unit of cable cores, the unit already having one or more sheaths.

The geometric design has been adapted so that the energy maximum lies in the microwave chamber. A person skilled in the field of High frequency technology can make such an adjustment, in particular a necessary impedance matching of the structure.

M2. Microwave system according to embodiment Ml, wherein

(i) the one or more chambers or the walls of the chambers, Alumini ^¬ to contain or consist of, and / or

(ii) the inner walls of the chambers with microwave absorbing additives, preferably silicon carbide or a polymer containing a microwave absorbing additive ^¬ coated.

Preferably, the walls of the chambers are made of aluminum, the walls may be coated and can include additional components, for example additional game ^¬ metal plates or chamber walls made of aluminum or other material to enhance the absorbent capacity. For example, the chamber could be equipped with a double wall.

M3. Microwave system according to embodiment Ml or M2, wherein

(i) at least one absorber assembly is adapted with a plurality of chambers in cross-section at the opening of the mono-mode microwave chamber, to absorb the exit ^¬ de microwave radiation, and / or

(ii) the chambers of the absorber assembly are provided with two opposing openings.

M4. A microwave system according to one of the embodiments M1-M3, wherein the magnetron generates microwaves at a frequency of 2450 MHz ± 100 MHz.

M5. Microwave system according to one of the embodiments M1-M4, wherein

(i) at least one absorber arrangement is arranged after the microwave chamber in such a way that a cable can be passed through this absorber arrangement after passing through the microwave chamber; and or

(ii) at least one absorber arrangement is arranged in front of the microwave chamber in such a way that a cable can be led through this absorber arrangement before passing through the microwave chamber.

M6. Microwave system according to one of the embodiments M1-M5, wherein at least one absorber arrangement is present, which has two or more chambers and a round and / or concentric geometry. M7. Microwave system according to embodiment M6, wherein the two or more chambers of the at least one absorber arrangement are spaced from each other.

M8. Microwave system according to one of the embodiments M1-M7, wherein the chambers of the absorber arrangement have openings with a diameter of> 1mm millimeter.

M9. Microwave system according to one of the embodiments M1-M8, wherein the system for impedance matching via the mechanical displacement of the short circuit (idle) is adjusted in the waveguide.

This adaptation can be carried out semi-automatically or preferably fully automatically by software-assisted evaluation of the scattering parameters, which are known to the person skilled in the art, e.g. is known by stepless screws.

The openings of the absorber arrangement are dependent on the line to be crosslinked. A cable core preferably has a diameter of> 1 mm.

MIO. A microwave system according to any of embodiments M1-M9, wherein the monomode microwave chamber and the chambers of the absorber assembly are configured to transport an endless cable through the chambers for irradiation purposes.

MII. Microwave system according to one of the embodiments MI-MIO, wherein the magnetron has a power consumption of up to 6 kilowatts.

M12. A microwave system according to one of the embodiments Ml-Mll, wherein the mono-mode microwave chamber has a cylindrical or rectangular shape, wherein the mono-mode microwave chamber and the chambers of the absorber arrangement comprise two opposing openings, through the middle of an existing cable transport system, a silicone rubber containing mass on i) a metallic cable core, or

ii) a cable core, or

is applied, can be performed. The microwave chamber may be cylindrical or rectangular. The geometry depends on which local point the field maximum for silicon crosslinking builds up. The mechanical length of the waveguide is adapted to the electrical length of the transmission path, so that the field maximum shifts into the microwave chamber.

The cable transport system consists of a cable reel unwinder and rewinder (as detailed in relation to cable manufacture elsewhere).

M13. Absorber arrangement as defined in one of the embodiments M1-M8.

M14. Use of an absorber arrangement as defined in one of the embodiments M1-M8 for absorption and at least partial reflection, preferably for absorption, of microwave radiation.

The microwave chamber can be cylindrical or rectangular. The geometry depends on which local point the field maximum for silicon crosslinking builds up.

M15. Use according to embodiment M14, wherein the microwave radiation is generated for curing a polysiloxane-based insulating layer of a cable.

M16. Use of a microwave system according to one of the preceding embodiments for crosslinking a polydimethylsiloxane-based silicone insulating layer as a cable sheathing or sheathing a metallic

Cable wire core.

M17. Use of a system consisting of a magnetron and a hollow ^¬ conductor, which connects the magnetron with the mono-mode microwave chamber, for microwave crosslinking of insulating layers based on silicone, preferably to a microwave crosslinking according to the method of embodiment 1.

M18. Use of an impedance matching system in a method according to any one of Embodiments 1-32. The impedance matching can be carried out by mechanical displacement of the short circuit or idle in the waveguide or an adjustment semi-automatic or preferably fully automatically by software-based evaluation of the scatter parameters by vectorial network analysis. M19. Use of microwave absorbers in a method according to any of the embodiments described herein, attached to the openings of the microwave chamber to reflect back or absorb leakage radiation into the chamber. In this case, the absorbers are so spaced from the openings or the microwave chamber, that the maxima of the radiation can be adjusted so that they fall into the chambers of the absorber.

40. Cable or cable core with bubble-free insulating layer based on silicone, produced or manufactured using the method according to any of embodiments 1-32, wherein the wall thickness of the insulating layer based on silicone is preferably 0.5 mm - 4.0 mm.

The present disclosure will be further explained with reference to figures:

FIG. 1 a shows a known process for crosslinking silicone coatings by heating in infrared furnaces.

FIG. 1b shows the method according to the invention for crosslinking silicone coatings using microwave radiation.

Figure 2 shows a series arrangement of 4 absorber chambers, through which a conductor is led with coating of silicone rubber-containing mass.

Examples

The absorber arrangement and the magnetron are not shown in FIG. 1b. Figure lb shows a cable 14, which is guided over wire guides (coils) 13 by the extruder 12 for Kaltextrusion (about 25 ° C) and then heated in the microwave chamber 11.

FIG. 2 shows an absorber arrangement 15 with a series arrangement of four absorber chambers 16, through which a conductor 14 with a coating of silicone rubber-containing compound is guided.

The production of cables or cable cores according to the invention can be carried out as described below. 2

20

First, the system must be cleaned and assembled. First, the screw and the cylinder are cleaned and the extrusion head is assembled including tools. The coil with the conductor is installed in the unwinder and the conductor itself is passed through the extrusion head. The microwave system is then positioned and aligned so that the conductor passes centrally through the microwave chamber.

The uncrosslinked silicone rubber-containing mass is applied to the roll. For this purpose, all components of the uncrosslinked silicone rubber-containing compound are added to the roller and rolled all homogeneously together to form a so-called "coat." From the coat about 2-3 kg pieces are cut and rolled up fed.

Once the silicone mixture and equipment have been prepared, the extruder is started. First, it must be completely filled with the material. Once this is done and silicone comes out of the nozzle, a program is started. This program regulates the power of the magnetron as a function of the extrusion speed. First, it is started slowly and the microwave is switched on, after a few seconds the microwave has started up and still has to be adjusted. That the impedance must be adjusted to the cross section of the conductor. However, this is done automatically via software or should be stored as a recipe in the system. Shortly thereafter, the speed is adjusted to production conditions, at the same time the performance of the magnetron is adjusted. The start should be within a few seconds. The networked cable is then wound up on a spool. It may even have to be talcum-treated beforehand or treated with another release agent, but that is independent of the crosslinking process.

Quoted pamphlets

EP1655328B1, DE19855718, EP1900767 Bl, US 4,980,384, US 4,460,713,

EP0945916

Claims

claims

A method of making a cable or cable core having one or more silicone-based insulating layers, comprising the steps of: a) applying an uncrosslinked silicone rubber-containing composition comprising polysiloxanes containing the basic building block Si (R, P) O, wherein R and R ¹ independently represent organic substituents, wherein different SiCR ^ O units may be present in a polysiloxane molecule, by means of an extrusion process

i) one or more metallic cable cores (e), or ii) a cable core, or

iii) a plurality of cable cores combined into a unit, wherein the unit may already have one or more insulation layers as a sheathing of the cable cores,

to form an insulating layer, wherein

the silicone rubber-containing composition contains no dielectric, inorganic additives other than silicon oxide / silicon oxides; and b) crosslinking the applied silicone rubber-containing mass in a monomode microwave chamber with continuous radiation of 2450 MHz ± 100 MHz, continuously passing the applied silicone rubber-containing mass through the monomode microwave chamber, wherein the crosslinking is in accordance with one or more of both of the following take place:

i) addition crosslinking, wherein one or more of R and R 'of a polysiloxane molecule are alkenyl substituents which react with silane groups of oligosiloxanes contained as crosslinking agents in the silicone rubber-containing composition in the presence of catalytically active salts and or metal complex catalysts; and ii) peroxide crosslinking, wherein R and / or R ^x of different polysiloxan molecules link in the presence of peroxides. The method of claim 1, wherein the silicone rubber-containing composition

(i) 5-40 wt .-% SiO ₂ , preferably wt .-% 20-40%, pyrogenic SiO ₂ or precipitated silica, and / or

(ii) contains no ferrites, and / or propellants.

The method of claim 1 or 2, wherein at least one absorber assembly is disposed on at least one of the openings of the microwave chamber to absorb and reflect microwave radiation along the passage of the applied silicone rubber-containing mass through the mono-mode microwave chamber.

The method of any one of claims 1-3, wherein the uncrosslinked silicone rubber-containing composition comprises:

(i) wt .-% contains 60-70 polysiloxane molecules in which one or meh ^¬ eral of R and R are vinyl groups, the vinyl group-containing polysiloxanes are polydimethylsiloxane preferred, and / or

(ii) 10-40%, preferably 20-40%, or 20-30%, hydrophobic fumed Kie ^¬ selsäure, which is preferably surface-modified, and / or

(iii) high temperature ("crosslinking, preferably crosslinkable at a temperature above 95 ° C.

The method of any one of claims 1-4, wherein

(i) the molecular weight of the uncrosslinked polysiloxanes 250,000 to

900,000 g / mol, and / or

(ii) the uncrosslinked silicone rubber-containing composition is solid (MQ / VMQ) or liquid (LSR) and the degree of polymerization of the uncrosslinked polysiloxanes is preferably 5,000-10,000 for solid silicone rubber and 600-1,800 for liquid silicone rubber.

The method of any of claims 1-5, wherein

(I) the radicals R and R 'of the polysiloxanes are independently selected from the group consisting of substituted or unsubstituted d-Ce-alkyl groups and substituted or unsubstituted C 1 -C ₈ -alkenyl groups, and / or

(ii) the uncrosslinked silicone rubber-containing composition preferably contains dimethyldimoxanes (MQ) and / or copolymers of dimethylsiloxane and vinylmethylsiloxane (VMQ).

The method of any of claims 1-6, wherein the microwave radiation

(i) is used as sole heat source; and or

(ii) with a power of at least 900 W, is radiated.

The method of claim 1, wherein one or more of R and R 'of a polysiloxane molecule are alkenyl substituents.

The method of any of claims 1-8, wherein

(i) two or more poly (organo) siloxane insulating layers are present and these are applied either sequentially or simultaneously, and / or

(ii) the cable core, or more are combined to form a unit cable wires, already having one or more temperature-sensitive insulation layers ^¬ / have, in particular polyolefins, PVC, and thermoplastic elastomers.

The method of any of claims 1-9, wherein

(i) the cable core has a diameter of> 1 mm, and / or

(ii) the silicone insulation layer has a layer thickness of 0.5 mm - 4.0 mm.

11. The process of any of claims 1-10, wherein the addition cure is a two component (2K) platinum catalyzed reaction (hydrosilylation).

12. The method according to any one of claims 1-11, wherein the silicone rubber-containing composition is based on a one-component silicone rubber, wherein the polysiloxane is either peroxide-crosslinking and the peroxide is mixed ^¬ , or addition-crosslinking, wherein the crosslinker already in the polysiloxane is bound and the platinum catalyst is mixed.

The method of any of claims 1-11, wherein the silicone rubber-containing composition contains no additive selected from the group consisting of: silicon carbide, silicon carbonitride, carbon nanotubes, iron compounds, carbon black, and metal oxides.

14. Use of a microwave system, comprising

(i) a magnetron for generating an unpulsed, electromagnetic radiation,

(ii) a mono mode microwave chamber with two opposing openings,

(iii) a waveguide connecting the magnetron to the monomode microwave chamber,

(iv) at least one absorber arrangement on at least one of the openings of the microwave chamber, the absorber arrangement having one or more chambers, and

(v) a system for impedance matching the microwave system, for the microwave cross-linking of silicon-based insulating layers, preferably for microwave crosslinking according to a method according to any one of claims 1-10.

A cable or cable core having a bubble-free silicone insulating layer, preparable or manufactured using the method of any one of claims 1-13, wherein the wall thickness of the silicone-based insulating layer is preferably 0.5 mm - 4.0 mm.

16. The cable or cable wire according to claim 15, wherein a temperaturempfindiiche shroud is present under the insulating layer ^¬ based on silicone.