WO2024088848A1

WO2024088848A1 - Formulation for an insulation system, use of same and moulded body

Info

Publication number: WO2024088848A1
Application number: PCT/EP2023/078988
Authority: WO
Inventors: Steffen Lang; Marek Maleika; Niels Müller; Florian Schemmel
Original assignee: Siemens Aktiengesellschaft; Siemens Mobility GmbH
Priority date: 2022-10-24
Filing date: 2023-10-18
Publication date: 2024-05-02

Abstract

The invention relates generally to the field of insulation, more particularly to a formulation for a high-temperature insulation at operating temperatures of 200°C and higher. The insulation is used to insulate electric conductors. The invention thus relates to an insulation system for an electric machine, more particularly a rotating electric machine with a stator, such as an electric motor and/or a generator with improved temperature resistance of the polymer insulation system components and/or an insulating coating for generatively manufactured conductors or parts thereof, busbars, connecting bars and/or terminal boxes. The present invention discloses for the first time a compound, powder coating and/or formulation for a wet coating, which comprises high-performance thermoplastics as fillers, wherein it has been shown that these fillers can considerably increase the thermal resistance and provide even better thermomechanical properties in an insulation system produced therefrom.

Description

Formulation for an insulation system, use thereof and molded article

The invention generally relates to the field of insulation, in particular to a formulation for high-temperature insulation at maximum operating temperatures of up to 200 ° C and more. The formulation, in the form of the molded body obtainable therefrom by curing, serves as an insulation system, as an insulating coating for electrical conductors and/or as a part thereof. The invention therefore also relates to a molded body which is at least part of an insulation system for an electrical machine, in particular a rotating electrical machine with a stator, such as an electric motor and/or a generator, with improved temperature resistance of the polymeric insulation system components. The invention also relates to a molded body as part of an insulating coating or as a whole forming an insulating coating, in particular the insulating coating of - for example - electrical conductors produced in an additive process, of busbars, of connecting rails and/or the insulating coating of terminal boxes.

Electrical machines for drive systems in general are equipped with a stator, as in motors and generators in the medium and high voltage range, and comprise electrical conductors, main insulation, conductor insulation, such as wire insulation with partial conductor insulation, and stator core. The main insulation serves the purpose of electrically isolating the phases from each other, from the earthed stator core, and from the environment.

The conductor insulation insulates the conductors of the coil from each other. The electrical machines are usually operated at the highest possible current densities. Traction motors are operated at high temperatures - e.g. thermal class of polymer-based plastics up to 220 ° C. The polymer Plastics that can therefore be used for this purpose are limited to a few types of polymers.

On the other hand, a wound insulation system includes not only surface insulation materials and/or insulation tapes, but also impregnating resin. The surface insulation materials - which form the slot lining and/or the insulation tapes, for example - are based on mica and glass, but also mainly on mAramid and/or polyimide due to a wide variety of requirements. Duromers with polyesterimide and/or silicone are usually used as impregnating resin in traction motors because of the high thermal class resulting from the low processing temperature. Epoxies are usually used in industrial high-voltage motors.

In insulation systems with mica tapes, the paper is combined with a glass fabric carrier and/or a PET and/or PI film and cut into narrow rolls, which then form the insulation tapes and are wound - e.g. around the conductor or the coil.

PEEK, PI, PAI, PPS, PEI, polyesterimide (duromer) and similar synthetic resins are conventionally used for extruded conductor insulation and/or for braided, tape-shaped conductor insulation - less so for solvent-based wire enamels. Above all, duromer wire enamels are commercially available for conductor insulation and have been optimized with regard to TE resistance.

Hairpin technology is a winding technology for stators in electric motors and generators, which is a subgroup of wave windings. It is used in particular in traction motors for electric vehicles. In contrast to preformed coil winding technology, wave winding technology is based on wire windings which are inserted into the stator slots of the laminated core individually and not combined as coils. These plug-in coils, so-called hairpins, corrugated hairpins (“continuous hairpins”) and/or I-pins are wave-shaped, U- or I-shaped bent lacquered and/or extruded flat copper wires.

I-pins, for example, are straight-line flat copper wires. In the wave winding concept "Continuous Hairpin", so-called winding mats are produced and then inserted into the laminated core from the inside. In comparison to U- and I-pin technology, this means significantly less effort in the connection technology of the individual pins.

The structure of a hairpin stator differs from conventional stators only in the type of winding system - the other components of the stator remain largely unchanged. The windings in the form of insulated winding wire are implemented in the hairpin stator using plug-in coils.

Hairpin technology, which is a modern technology for stators in electrical machines, is trying out new, more cost-effective methods. For example, the flat copper wire with typical hairpin geometry is inserted into the slots of the laminated core using a forming-based assembly process. However, it is essential to insulate the soldered or welded connection points between the individual hairpins with a coating, as these are not protected by the conductor insulation. However, the thermal resistance of the paints currently used is limited to a heat class of 180 (H). To produce the finished insulation system, it is preferable to fix the winding, the wire and/or the hairpin in the groove by casting, impregnating, dripping, dipping and/or by injection molding with a synthetic resin. Alternatively, a partial conductor insulated by wire extrusion can be fixed in the groove by injection molding.

There is still a need for an improved technology for a formulation for producing an insulation system and/or an insulating coating, in particular also suitable for the above-mentioned applications - also for use in plug-in coil and/or wave winding technology - for example, usable in traction motors for rail vehicles, passenger cars, trucks and/or for insulating coating, for example of terminal boxes, additively manufactured conductors and/or coils, as well as power or connecting rails.

The object of the present invention is therefore to create a formulation for an insulating coating and/or an insulation system for an electrical rotating machine, in particular for use at maximum operating temperatures of more than 170 ° C, in particular of 200 ° C and above, preferably even of a maximum of 220 ° C and above, which is also suitable for use in plug-in coils and/or wave winding technology.

This object is achieved by the subject matter of the present invention as disclosed in the claims, the description and the examples.

The invention therefore relates to a formulation for an insulation system and/or an insulating coating, in the form of a potting compound, powder coating and/or solvent-containing wet coating, comprising at least one component B, wherein also a component A, an uncrosslinked, liquid or solid base resin with the hardener and/or accelerator required for curing is preferably included and component B is present as PFT, i.e. in the form of a polymeric filler which is solid at room temperature under normal conditions and has a high relative temperature index, in particular greater than 160 ° C, wherein component A is present in the range of 0% to 99% by weight and component B is present in the range of 1% to 100% by weight, based on 100% of the solvent-free formulation.

The present invention further relates to a shaped body obtainable by curing the formulation described above, wherein the shaped body forms an insulation system or parts of an insulation system and/or an electrically insulating coating or parts of an electrically insulating coating.

Finally, the invention relates to the use of a formulation as described above for producing an insulation system, an insulating coating and/or a conductor insulation by powder coating, fluidized bed coating, wet painting and/or potting.

The term "relative temperature index" here means the relative temperature index according to IEC 60216 or DIN EN 60216 "TI". This corresponds to the numerical value of the temperature in ° C, which is derived from the long-term thermal relationship for a period of 20,000 hours at 5% mass loss.

After curing, a formulation according to the invention forms an insulation system in the form of a conductor insulation and/or parts of a conductor insulation. The formulation is processed, for example, but not exclusively, by means of powder coating, potting, fluidized bed and/or wet paint coating of conductors, parts of conductors and/or housings. Curing to form the molded body is preferably carried out thermally and/or via radiation, in particular UV curing.

A molded body made from the formulation can then - for example - partially or completely form the insulation of one or more individual rods, of the winding head and/or of the switching area of a winding head and/or even the insulation of an entire wire winding. It can also function as partial conductor insulation and/or as individual rod insulation of a plug-in coil, of another conductor element in wave winding technology and/or as an insulating coating of a generatively, in particular additively, manufactured conductor element.

Finally, the formulation may constitute, in whole or in part, an insulating coating of current and/or connecting rails and/or terminal boxes.

Conductor insulation is, for example, the electrical insulation of the individual conductor turns of a coil against each other and/or the conductors of a wire winding and/or against the environment and/or against ground, e.g. of the electrical machine.

Fluidized bed coating is the coating of a conductor in a fluidized bed that is filled with a powder coating formulation. In particular, a powder made of compounds that are solid under normal conditions is used, which means that the base resin is preferably also in solid form, in addition to the thermoplastic, which is already solid in particle form.

Powder coating, particularly electrostatic powder coating, is carried out, for example, by spraying and/or using a fluidized bed process. A powder made of solids is used, which means that in addition to the thermoplastic, which is already solid in particle form, the base resin is also present as a solid. Wet painting is carried out, for example, by painting, brushing, dipping, spraying, spin coating and/or dipping processes. The formulation is applied to the conductor dissolved in a solvent, the solvent is then - at least partially - removed and the formulation hardened. The base resin can be in the form of a solid and/or a liquid.

Casting is carried out with a liquid formulation without solvents, whereby the base resin, in contrast to the formulation which is used as a powder coating, is present as a liquid under normal conditions.

The term "normal conditions" - a particularly relevant aspect with regard to processing conditions and storage stability - refers to 25 °C room temperature, ambient air and normal pressure.

The general finding of the invention is that in a formulation for a casting, as a fluidized bed powder, as a powder coating and/or for a wet coating for producing an electrical insulation system and/or an insulating coating, the incorporation of solid and polymeric plastic filler particles with a high relative temperature index, polymer filler with a high relative temperature index "PET" brings advantages with regard to thermomechanical stability and in particular with regard to temperature stability.

This is particularly advantageous when the power density of the electrical conductors is increased, because an increase in power density always also entails an increase in operating temperatures.

The PFTs according to the invention have a high temperature index "TI" which is in particular above 160 ° C, preferably above 170 ° C, particularly preferably above 180 ° C and very particularly preferably above 190 ° C. PFTs are preferably used with high glass Transition temperature is used. This is particularly the case with thermoplastic, elastomeric and/or thermosetting particles with a glass transition temperature greater than or equal to 130 °C, preferably greater than or equal to 150 °C, preferably in a mixture with component A, with a base resin, hardener and/or accelerator that is not yet crosslinked, where the presence of PFTs achieves clear mechanical and/or thermomechanical advantages and/or a significant increase in the temperature resistance of the resulting insulation system and/or the insulating coating.

The thermoplastic, elastomeric and/or thermosetting PFTs of component B are the same or different, for example with regard to material, surface treatment, surface coating, crystallinity, amorphousness, grain size, particle shape and/or fiber reinforcement. The PFTs are preferably deagglomerated.

Component B contains the PFTs and is present in the dry formulation in a mass fraction based on 100 parts by mass of solvent-free formulation in the range from 1% to 99% by mass, in particular from 10% to 60% and very particularly preferably from 20% to 50% and particularly preferably in the range from 20% to 30% by mass based on 100 parts by mass of solvent-free formulation.

The "base resin" with, if necessary, hardeners, accelerators, additives, additional materials and other fillers then forms the remainder of the 100% by weight of the solvent-free formulation.

The term "base resin" in the sense of "main component of the formulation" is no longer applicable according to this invention because, if component B represents more than 50% by mass of the formulation, the resin is sometimes only used as a binder or - for example in a powder coating formulation - not used at all. According to an advantageous embodiment of the invention, the base resin in the formulation as component A is in the form of a not yet cross-linked duromer resin which comprises one or more compounds selected from the group epoxy resin, polyurethane resin, polyisocyanate resin, polyimide resin, polyesterimide resin and/or polyester resin in any mixtures, blends and/or copolymers. For example, the duromer uncross-linked synthetic resin in the formulation comprises compounds such as bisphenol A diglycidyl ether, bisphenol F diglycidyl ether, novolak, aliphatic epoxy resin and/or aromatic epoxy resin. When used solvent-free as a casting compound and/or as a solvent-containing wet paint, the base resin can also be liquid under normal conditions; when used as a powder paint it is a powder, i.e. a solid.

For this purpose, component A contains a hardener in a stoichiometrically suitable amount and chemically compatible with the base resin, which is based, for example, on anhydride, imidazole, bisphenol and/or dicyanamide.

To initiate hardening after application - e.g. spraying on the powder coating - of the formulation on the body to be insulated, for example a plug-in coil in hairpin technology, component A can also contain an accelerator in small quantities, e.g. in the range of 0.3 to 2% by weight. Accelerators for this application are known to the person skilled in the art; for example, urea such as dimethylurea, 1,l-dimethyl-3-phenylurea, toluyl-bis-1,1-dimethylurea, 3-(3-trifluoromethylphenyl)-1,1-dimethylurea, 2-phenylimidazole and/or benzyldimethylamine can be used as accelerators.

Powder coating can also be used to particular advantage in the insulation of individual rods using hairpin, wave winding and/or plug-in coil technology. Individual rods can be coated with powder coating, e.g. automatically. in an assembly line process, coated or sprayed, which are then subjected to thermal and/or UV curing.

As a wet paint, the formulation is dissolved in a solvent. Suitable solvents include: acetone, isopropanol, ethyl ester, methyl ethyl ketone, butyl acetate in any mixture and/or combination. A common thixotropic agent may also be added to the wet paint.

According to a further advantageous embodiment, the PFTs of component B are present in grain sizes in the range of 1m to 3mm, preferably from 0.1pm to 1000pm. The PFTs in component B can be the same or different in terms of their grain size and particle shape. In particular, different thermosets and/or thermoplastics and/or different grain sizes of a plastic can also be mixed.

It has proven particularly advantageous to incorporate at least one particle fraction with an average grain size d50 in the range from 500 nm to 300 pm, in particular from 1 pm to 200 pm and for example in the range from 2 to 100 pm, for example between 2.5 pm and 10 pm.

For example, component B contains a multimodal mixture of particles of different grain sizes, so that coarser and finer fractions complement each other, particularly with regard to the mechanical properties when processing the formulation. It is known that smaller particle fractions can act like ball bearings for coarser particles with regard to the flowability of the formulation.

The PFTs of component B can - depending on requirements - be amorphous, semi-crystalline, with crystalline parts, or in any mixture of the aforementioned modifications in the formulation. Parts or all of the PFTs of component B can also be reinforced, in particular fiber-reinforced. All types of non-electrically conductive fillers can be used. Materials may be incorporated, for example aramid fibre-reinforced or glass fibre-reinforced thermoplastic particles may be contained in component B.

The PFTs include, for example, polymeric solid filler particles made of materials such as high-performance plastics - preferably with a relative temperature index greater than 190°C and preferably greater than 200°C - such as:

Thermoplastic polyimides - TPI-, see also structural formulas I to III, polyetherimide - PEI-, polybenzimidazole -PBI-, thermoplastic silicone, in the form of solid polymer filler particles after appropriate frost treatment, polyamideimide -PAI-, polyether ketones such as e.g.

Polyetheretherketone -PEEK-, polyetherketoneketone -PEKK-, polyetherketoneetherketoneketone -PEKEKK-, polyetherketone -PEK-, polymeric sulfur compounds, such as polysulfone -PSU-, polyphenylene sulfide -PPS-, polyethersulfone -PES-, polyphenylenesulfone -PPSU-, each alone or in any mixtures, blends and/or copolymers present in the particle.

For example, component B comprises PFTs made of a thermoplastic polyimide - TPI-, which corresponds to the structural formula I : Structural formula I

and/or structural formula II

Structural formula II

with

- applies to both structural formulas I and II - n = 1 to 10 000

R is the same or different and stands for any aliphatic and/or aromatic organic, hydrocarbon-based, optionally heteroatom-substituted, organic radicals with any functional groups.

Therefore, R can be alkyl, aryl, O,S-alkyl, O,S-aryl, N,P-aryl, N,P-alkyl with any functional groups, such as acid groups, ester groups, ether groups, etc.

According to another embodiment, component B comprises, for example, PFTs from a TPI which comprises the structural formula III - at least as a component:

Structural formula III

Again with n in the range 1 to 10 000 .

A thermoplastic compound comprising an element with structure III can also be present as a component of any copolymer and/or blend as PET in component B.

Particles made of thermoplastic high-performance plastics with the above-mentioned structural formulas I to III can, for example, have glass transition temperatures Tgs of up to 350 °C.

Thermoplastic high-performance polymers such as PET, for example, can be present in pure form but also in any blends and/or copolymers in PFTs of component B.

Component B includes, for example, various particle fractions, each containing different high-performance plastics.

PFTs of component B may be coated or uncoated.

PFTs of component B, for example, are surface-treated, whereby chemical and/or physical functionalization of the surface with regard to better bonding to the duromeric resin represents one possibility for surface treatment.

Preferably, component B comprises at least one particle fraction of PFTs having fiber-reinforced particles. In addition to component B, the formulation may contain other fillers such as quartz powder, fused silica, mica, siloxane alone or in any mixture.

In addition, the formulation may also contain the usual additives for potting, powder coating or wet coating, such as flow agents, degassers and any other well-known additives for electrical insulation systems.

In the following, the invention is explained in more detail using some examples.

Example 1 :

Base resin Bisphenol A: 46.5 %

Hardener Dicyandiamide: 0.5%

Accelerator: Toluyl-bis-1,1-dimethylurea: 0.5%

Filler: Quartz powder: 20 %

Filler 2: Siloxane-polyimide copolymer 10%

Polymeric filler with high temperature index "PFT" : Polyimide, structural formula II 20% Additive: Flow agent 1%

Additive: Degasser 1.5

Example 2 :

Base resin Bisphenol A: 55.5%

Hardener Dicyandiamide: 1 %

Accelerator: Toluyl-bis-1,1-dimethylurea: 1% PET: Polyimide, structural formula II 40%

Additive: Anti-crater and leveling agent 1.5%

Additive: Degasser 1%

By adding the PFTs in component B, an increase of 154 °C in the temperature index measurement was achieved. pure DGEBA/DICY formulation to 183 ° C of the formulation containing 30% component B in the form of PFTs based on thermoplastic polyimide.

The presently disclosed invention provides an insulation formulation for insulation systems as well as insulating coatings which shows a drastic improvement over the prior art, in particular the base resins without PFTs, because it simultaneously provides a

- excellent resistance to environmental influences,

- sufficient - 3 months or longer - storage stability at room temperature,

- Improved thermomechanical behaviour of the resulting insulation systems and insulating coatings and

- shows good processability as casting, powder coating or wet paint.

The invention relates generally to the field of insulation, in particular to a formulation for high-temperature insulation at operating temperatures of 200 °C and more. The insulation serves as insulation for electrical conductors. Thus, the invention relates to an insulation system for an electrical machine, in particular a rotating electrical machine with a stator, such as an electric motor and/or a generator with improved temperature resistance of the polymeric insulation system components and/or an insulating coating for generatively produced conductors or parts thereof, busbars, connecting rails and/or terminal boxes.

The present invention discloses for the first time a formulation for a powder coating, for a powder for a fluidized bed, for a casting resin and/or a formulation for a wet coating, which contains as component B PFTs, i.e. high-performance plastics in fully cured, polymeric and - even at Thermoplastics - in solid form, it has been shown that PFTs can significantly increase the thermal resistance of the resulting material and at the same time bring improved thermomechanical properties to an insulation system and/or an insulating coating made from it. The invention is used to produce insulation systems for electrical rotating machines. Other areas of application for the formulation according to the invention are, for example, insulating coating of generatively produced conductors, busbars and/or connecting rails as well as the coating of terminal boxes.

Claims

Patent claims

1. Formulation for an insulation system and/or an insulating coating, in the form of a casting, powder coating and/or solvent-containing wet coating, comprising at least one component B, wherein component A, an uncrosslinked, liquid or solid base resin with the hardener and/or accelerator required for curing, is also preferably included, and component B is in the form of a PFT, i.e. in the form of a polymeric filler which is solid at room temperature under normal conditions and has a high relative temperature index, in particular greater than 160 °C, wherein component A is present in the range from 0% to 99% by weight and component B is present in the range from 1% to 100% by weight, based on 100% of the solvent-free formulation.

2. Formulation according to claim 1, wherein the base resin comprises one or more compounds selected from the group consisting of epoxy resin, polyurethane resin, polyisocyanate resin, polyimide resin, polyesterimide resin and/or polyester resin, alone or in any mixtures, blends and/or copolymers.

3. Formulation according to one of claims 1 or 2, wherein the hardener comprises a compound which is based on anhydride, imidazole and/or dicyanamide, as well as any derivatives and/or mixtures of these compounds.

4. Formulation according to one of the preceding claims, wherein component A comprises an accelerator.

5. Formulation according to one of the preceding claims, which comprises further fillers such as fused silica, quartz powder and/or siloxane, alone or in any mixtures and combinations.

6. Formulation according to one of the preceding claims, which is present as a wet paint in a solvent such as acetone, isopropanol, ethyl ester, methyl ethyl ketone, butyl acetate in any mixtures and/or combinations.

7. Formulation according to one of the preceding claims, which comprises in component B PFTs with grain sizes of 1m to 3 mm.

8. Formulation according to one of the preceding claims, which comprises in component B PFTs with grain sizes of 0.1 pm to 1000 pm.

9. Formulation according to one of the preceding claims, which comprises in component B at least two different particle fractions of PFTs with grain sizes of 1 mn to 3 mm.

10. Formulation according to one of the preceding claims, wherein component B comprises PFTs made of high-performance plastic such as thermoplastic polyimides - TPI-, see also structural formulas I to III,

Polyetherimide - PEI-, polybenzimidazole -PBI-, polysiloxane, polyamideimide -PAI-, polyetherketones such as polyetheretherketone -PEEK-, polyetherketoneketone -PEKK-, polyetherketoneetherketoneketone -PEKEKK- polyetherketone -PEK-, polymeric sulfur compounds such as polysulfone -PSU-, polyphenylene sulfide -PPS-, polyethersulfone -PES-, polyphenylenesulfone -PPSU-. each present alone or in any mixtures, blends and/or copolymers in the particle.

11. Formulation according to one of the preceding claims, wherein component B comprises various PFT particle fractions, each containing different high-performance plastics.

12. Formulation according to one of the preceding claims, wherein component B comprises several different particle fractions with PFTs of different degrees of crystallinity, i.e. amorphous, semi-crystalline and/or crystalline PFTs.

13. Formulation according to one of the preceding claims, wherein component B comprises at least one fiber-reinforced PFT particle fraction.

14. Shaped body obtainable by curing a formulation according to one of claims 1 to 13, wherein the shaped body forms an insulation system or parts of an insulation system and/or an electrically insulating coating or parts of an electrically insulating coating.

15. Use of a formulation according to one of claims 1 to 13 for producing an insulation system and/or an insulating coating by casting, powder coating, fluidized bed coating, wet painting and/or conductor insulation.