EP4003954A1

EP4003954A1 - Tape accelerator and use thereof, solid insulating material, and anhydride-free insulation system

Info

Publication number: EP4003954A1
Application number: EP20764002.0A
Authority: EP
Inventors: Mario Brockschmidt; Jürgen Huber; Torsten Rossow; Dieter Schirm; Matthias ÜBLER
Original assignee: Siemens AG
Current assignee: Innomotics GmbH
Priority date: 2019-09-04
Filing date: 2020-08-11
Publication date: 2022-06-01
Also published as: WO2021043541A1; US20220235199A1; CN114599720A

Abstract

The invention relates to a tape accelerator and a solid insulating material comprising said tape accelerator, as can be used for the production of an anhydride-free insulation system for motors and generators, for example in the form of a wrapping tape insulation. In particular, the invention relates to an anhydride-free insulation system that can be produced using a vacuum pressure impregnation (VPI) process. Such an insulation system comprises a solid insulating material from which the anhydride-free insulation system is produced by means of impregnation and/or encapsulation with an impregnation agent and subsequent curing. The invention provides for the first time a solid insulation material which has a tape accelerator and optionally suitable tape adhesive and which, using an anhydride-free impregnation agent, quickly and completely provides a stable insulation system, even in areas without tape accelerator, under the conditions, for example, of vacuum pressure impregnation.

Description

description

Belt accelerator and its use, solid insulation material and anhydride-free insulation system

The invention relates to a belt accelerator and a fes th insulation material with this belt accelerator, as it can be used to produce an anhydride-free insulation system for motors and generators - for example in the form of a winding belt insulation. In particular, the invention relates to an anhydride-free insulation system which can be produced by vacuum-pressure impregnation -VPI- process. Such an insulation system comprises a solid insulation material, from which the anhydride-free insulation system is produced by impregnation and / or casting with an impregnating agent and subsequent curing.

Rotating electrical machines include an electrical winding within a laminated core, such as a stator winding. The winding is made up of electrical conductors, which may already be provided with primary insulation, and solid insulation materials as the main insulation against the laminated core. Without further measures, there is no intimate connection between the laminated core, the conductors and the main insulation, so that gaps and cavities remain. Under atmospheric conditions, these areas would be filled with air. In the case of applications in the medium and / or high voltage range, such as motors and generators or large electrical drives, this is not permitted, as partial electrical discharges in the cavities and gaps would destroy the insulation in a very short time. A resulting electrical breakdown, for example, means the failure of the electrical machine.

Therefore, a preferably bubble-free intimate connection between the Blechpa ket, the conductors and the main insulation is sought for the production of the insulation system. This is usually achieved through the use of solid insulation Material that forms a winding and subsequent impregnation with a so-called impregnation and / or impregnation resin, because it impregnates and / or impregnates the solid insulation material.

In the present case, this liquid resin component is called "impregnating agent" because, in addition to the actual resin component, the impregnating resin, it can also include hardeners, catalyst (s), thinners, additives, fillers, etc. Through the potting, in particular also the impregnation and impregnation of the solid insulation material in the laminated core with this impregnating agent can minimize imperfections.

Particularly suitable solid insulation materials are porous insulation materials such as mica tape, insulation paper, and / or nonwovens, as well as any combinations thereof.

For the insulation of rotating electrical machines in the medium and / or high voltage range, windings made of solid insulation materials are the usual state of the art technology, which by means of a vacuum pressure impregnation process -VPI - with mixtures with liquid epoxy resins and liquid, cyclic acid anhydrides be impregnated in the impregnation agent.

In addition to an optionally available basic structure, such as a fabric made of reinforcing fibers, the solid insulation material is a barrier material that is glued with a tape adhesive. Dissolved and / or finely distributed in it is the so-called "belt accelerator", which first initiates the gelation, i.e. the formation of the pre-hardened synthetic resin and then promotes complete hardening, provided that the polymerization of the liquid impregnation agent does not itself keep going. The tape adhesive serves - for example - to connect mica paper and carrier materials such as foils and / or glass fabric, whereas the proportional tape accelerator causes the low-viscosity impregnating resin to gel to the hardened synthetic resin. For this purpose, the liquid impregnating agent penetrating into the winding made of solid insulation material removes the belt accelerator from the solid insulation material and thus causes the belt accelerator to migrate and distribute in the impregnating agent. After gelation, the impregnated winding is thermally hardened in the manufacture of the finished anhydride-free insulation system.

Since the belt accelerator is provided as a depot in the solid insulation material, the impregnation never results in a completely homogeneous distribution of the belt accelerator in the impregnating agent. Rather, there are areas of high and low belt accelerator concentration.

The - in particular cyclic - acid anhydrides previously contained in the impregnation agent serve as hardeners for the epoxy groups and at the same time reduce the viscosity of the impregnation agent as a whole, which is beneficial for rapid and complete impregnation of the solid insulation material.

A mixture of distilled bisphenol A diglycidyl ether as the impregnating resin and a methylhexahydrophthalic anhydride as the anhydride-containing hardener has established itself as an impregnating agent as an impregnating agent, both together result in a very thin liquid formulation that, in the absence of a belt accelerator, can last for a long time Has storage stability at room temperature and also at impregnation temperature. This long storage stability is shown, for example, in a doubling of the dynamic initial viscosity only after several weeks, but in the presence of catalytically active compounds, such as those that are, for example, the belt accelerators that are in the solid If the insulation material is deposited, the mixture in the impregnant reacts quickly to form high polymers.

Conventionally, in the prior art, the preferred belt accelerator is a compound called zinc naphthenate, which is derived from petroleum. But other synthetic belt accelerators are known to the person skilled in the art, such as those from EP 0424376 Bl.

The cyclic acid anhydrides in the impregnating agent are, however, sensitizing compounds, especially airway sensitizing. This generally calls into question their unrestricted usability in the future. Methylhexahydrophthalic anhydride (MHHPA) in particular has been traded as a candidate for substances of particular concern for approval according to the REACh regulation since 12/2012 due to its airway sensitizing properties.

The development of completely anhydride-free insulation systems for rotating electrical generators and machines in the high-voltage area is therefore of great economic interest.

The use of anhydride-free impregnating agents based on epoxy resin for the impregnation of rotating electrical machines in the medium and high voltage range, however, requires a new development of the insulation system as a whole.

In particular, the composition of the solid insulation material, for example the mica tapes, and the coordination of tape adhesive and tape accelerator must be redesigned for the use of anhydride-free impregnation agents.

From EP 3227893, EP 3298611 and WO 2017153113 solid insulation materials are already known that react with anhydride-free epoxy resin-based impregnating resins to form insulation systems. Also from EP 3245063 are tape adhesives known for solid insulation materials for impregnation with anhydride-free impregnating agents.

However, a disadvantage of the systems known to date is that the tape accelerator / tape adhesive / impregnant mixtures exhibit too low a reactivity and thus incomplete curing in the areas of the winding with low concentrations of tape accelerators.

In particular, these belt accelerators no longer show sufficient effectiveness from concentrations of approx. 1% by weight and less, so that even after the solid insulation material has been impregnated with the impregnation agent and gelation and subsequent hardening, there are still liquid and unpolymerized parts of the impregnating resin in a quantity that prevent a resilient insulation system with only a small number of imperfections such as air bubbles from forming.

As an example, Table 1 shows the enthalpy of reaction of long-known anionic belt accelerators, which react with an anhydride-free impregnating agent, but in catalytic amounts of 1% by weight or less, as is always found in areas with a low concentration of belt accelerator when potting There is isolation, react too weakly.

A reaction enthalpy of -378 Jg ^_1 is sufficient for a stable insulation system, but a reaction enthalpy of - 8.3 Jg ^_1 is no longer. The proportions of impregnating agent that has not yet polymerized can be measured via DSC - differential scanning calorimetry as incomplete curing via the reaction exotherm.

Figures 1 and 2 show the DSC measurements for Table 1.

There are already better effective belt accelerators, in particular cationically acting, so so-called cationic belt accelerators, for example based on quaternary ammonium compounds, known, but these have the disadvantage that they reduce the temperature increases compared to room temperature that occur during winding and / or production of the solid insulation material with embedded belt accelerator, do not survive unscathed.

It is therefore the object of the present invention to provide a tape accelerator for storage in a solid insulation material with tape adhesive that is suitable for forming an insulation system with an anhydride-free impregnating agent. It is particularly important that the tape accelerator deposited in the solid insulation material during the impregnation process is sufficiently effective as a tape accelerator in areas of the winding with a low tape accelerator concentration.

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

Accordingly, the subject matter of the present invention is a cationic belt accelerator for use in a process for the production of an insulation system by impregnation and / or encapsulation with an anhydride-free impregnation agent, which is an ionically composed compound of one or more sulfonium-containing cation (s) with one or more hexafluoroantimonate anion (s). In particular, the subject of the present invention is a cationic belt accelerator for use in a process for the production of an insulation system by potting with an anhydride-free impregnating agent, the belt accelerator being a chemical compound that falls under one of the structural formulas I, II or III:

Structure i

FIG. 3 shows the structural formula “Structure I” of a cationic belt accelerator according to a preferred embodiment of the present invention.

The invention also relates to the use of the belt accelerator for producing an anhydride-free insulation system by impregnating the solid insulation material with an impregnating agent, the impregnating agent comprising an aromatic and / or cyclo-aliphatic impregnating resin that is anhydride-free and epoxy groups. is relevant.

Therefore, the subject matter of the invention as an independently tradable intermediate product comprises a solid insulation material, a barrier material, a tape adhesive and a tape accelerator, the tape accelerator being a cationic tape accelerator and an ionic compound of a sulfonium-containing cation with a hexafluoroantimontium anion , such as 4-acetyloxyphenyl-dimethylsulfonium-hexafluoroantimonate - CAS-No.135691 -31-5- structure I contains. Structure i

Finally, the subject of the invention is an insulation system, producible by casting a solid insulation material with a belt accelerator, which is an ionogenic compound composed of a sulfonium-containing cation with a hexafluoroantimonate anion, in particular a compound according to structural formula I with an anhydride -free impregnating agent, contains.

A compound according to structure I is in particular a compound available commercially under the name 4-acetyloxyphenyl-dimethylsulfonium-hexafluoroantimonate.

The general knowledge of the invention is that a solid insulation material which, as a cationic band accelerator, contains an ionogenic compound of a sulfonium-containing cation with a hexafluoroantimonate anion, in particular the compound of structural formula I at least in large part, with an anhydride -free impregnation resin, especially epoxy resin-based, also in areas with low belt accelerator concentrations, i.e. in areas with belt accelerator concentrations of 1% by weight or less, to the extent that the anhydride-free epoxy resin-based impregnating resin for the production of the insulation system during of the grout gels and / or hardens sufficiently so that a sufficiently stable insulation system with a tolerable number of defects can be produced in the tried and tested VPI manufacturing processes and associated VPI systems. One with the belt accelerator according to the invention The insulation system that can be produced is comparable in terms of the flaws with the conventional insulation systems according to the state of the art which can be produced using anhydride-containing impregnating agents.

A "cationic belt accelerator" is a belt accelerator which is ionogenic and whose cation in a liquid impregnant initiates the cationic polymerization, in particular the cationic homopolymerization of an impregnating resin.

Heteropolar compounds are referred to as "ionogenic" compounds, the chemical reactivity of which is characterized by the presence of a cation and an anion in the compound. Classical "ionogenic" compounds are salts. However, complex structures with a cationic and anionic character are also referred to here as "ionogenic" compounds.

A "sulfonium-containing cation" is a cation which, in addition to the anion or anions, comprises a unit in the molecule that can be described by the simply positively charged structures II or III or by the empirical formula [SRs] ⁺ . Cationic structure II

Ar r alkyl

Di-aryl-alkyl-sulfonium Cationic structure III

Ar

Alkyl

Di-alkyl-aryl-sulfonium

The term “alkyl-aryl-sulfonium or di-alkyl-aryl-sulfonium” denotes a sulfonium-containing cation in which one or two of the three radicals “R” on the sulfur atom in the sulfonium cation are alkyl groups. Alkyl groups are parts of a molecule that consist of carbon and hydrogen atoms connected to one another. For the purposes of the invention, preferred alkyl radicals are those with 1 to 12 carbon atoms, which can be branched or linear. The alkyl groups are monovalently linked to the central sulfur atom.

According to the invention, one or two alkyl radicals can be present in a di-alkyl-aryl-sulfonium cation, which in turn can be identical or different. The term “aryl-alkyl-sulfonium or di-aryl-alkyl-sulfonium” denotes a sulfonium-containing cation in which one or two of the three radicals “R” on the sulfur atom in the sulfonium cation are aryl groups. Aryl groups are parts of a molecule that are monovalent on the carbon structure or on the sulfur atom, and have at least one aromatic nucleus, which can be partially or completely - substituted or - unsubstituted. According to the invention, one or two aryl radicals can be present in an aryl-alkyl-sulfonium cation, which in turn can be identical or different.

The third radical can be any, including an alkyl group or an aryl group, completely or partially substituted or not.

An aryl group is an organic chemical radical with an aromatic backbone. It is the name for a monovalent group of atoms derived from aromatic hydrocarbons by removing a hydrogen atom bound to the ring. Most aryl groups are derived from benzene, the simplest aryl group is the phenyl group.

According to a preferred embodiment, at least one aryl group is present in the sulfonium cation.

It is preferred here if at least one mononuclear aryl group, for example an aryl group with an aryl structure derived from benzene, such as phenyl or benzyl, is present.

In particular, it is also preferred if at least one substitution is present on a mononuclear aromatic radical of the aryl group of the sulfonium-containing cation, that is, a hydrogen is replaced on the aromatic nucleus, for example by a functional group or an alkyl group.

The functional group can be present with or without a hetero atom such as oxygen, nitrogen, sulfur, phosphorus.

Particularly preferred is an aryl group in which a hydrogen is set on the aromatic nucleus by an acetyloxy group. Furthermore, it is particularly preferred that a sulfonium-containing cation combined with a hexafluoroantimonate anion is present as the belt accelerator.

According to one embodiment, there is essentially a compound as a cationic belt accelerator.

According to another embodiment, the belt accelerator is present as a mixture of at least two cationic belt accelerators, each of which has a different sulfonium cation. The anions can be the same or different. In particular, hexafluoro-antimonate is provided as the anion.

Mixing ratios of 1000 parts of the first belt accelerator to 1 part of the second belt accelerator up to equal proportions of the first and second belt accelerator are provided. Preferably, 100 parts of the first belt accelerator are mixed with 1 part of the second belt accelerator. It is particularly preferred that 10 parts of the first belt accelerator are mixed with 1 part of the second belt accelerator.

The belt accelerator, regardless of whether it is present as a single compound or as a mixture, preferably has a melting point in the range from 145 ° C to 165 ° C, particularly preferably in the range from 155 ° C to 160 ° C.

A "solid insulation material" is particularly a composite of a carrier, a barrier material, a tape adhesive and the tape accelerator. Depending on the size and shape of the barrier material, a carrier is present or not. The carrier is therefore optional.

An electrically insulating material is used as the barrier material, in particular one that can be glued together in the form of particles to form a flat structure such as a tape, paper or the like. Mica is particularly preferred in this context because mer also combines a particularly high dielectric strength with high temperature resistance. But all barrier materials that are suitable for storing the belt accelerator according to the invention and for producing an insulation system after casting, impregnation and curing can be used here.

The barrier material is preferably at least partially in the form of platelets.

According to an advantageous embodiment, a carrier in the form of woven material, such as glass fiber cloth, non-woven material ("non-woven") such as e.g.

Fleece, in particular a polyester fleece, paper and / or film before. The carrier can also be perforated in the form of a film.

The, preferably particulate, barrier material is located in the solid insulation material on, in and / or on this carrier.

According to one embodiment, a tape adhesive in the form of a glycidyl ether epoxy resin is in the solid insulating material. It is particularly preferred if the glycidyl ether epoxy resin is present with repeating units from n = 0 to n = 50, preferably from n = 1 to n = 30, particularly preferably from n = 2 to n = 18. The tape adhesive can also comprise epoxy novolak and / or epoxy phenol novolak, in particular in those with repeating units of n = 0.1 to n = 8.

According to a preferred embodiment of the invention, the solid insulation material comprises a tape adhesive in the form of a thermoplastic polyvinyl acetal and / or a polyester, for example a liquid polyester. According to an advantageous embodiment, the polyester comprises hydroxyl groups and / or carboxy groups as functional units.

Possible polyvinyl acetals are, for example, butyraldehyde and / or acetaldehyde.

Basically, the epoxy-containing tape adhesives show less good properties together with the tape accelerators according to the present invention than epoxy-group-free tape adhesives. The tape adhesive is, for example, in the form of a blend, so that proportions of epoxy-containing compounds together with the thermoplastic polyvinyl acetals and / or the polyesters are present, it being preferred that the properties of the thermoplastic polyvinyl acetals and / or the polyester dominate in the mixture that forms the tape adhesive.

The tape adhesive connects the at least one carrier and the barrier material in the solid insulation material, the insulation system. It is contained in the solid insulation material in an amount in the range from 1 to 30% by weight, preferably 2 to 15% by weight, particularly preferably 5 to 10% by weight.

The belt accelerator is embedded in the solid insulation material, which is present, for example, in the form of a belt, hence the term "belt accelerator". This can be done, for example, by applying a surface.

For example, the belt accelerator is embedded in the solid insulation material with an area coverage of 0.1 to 5 g / m ² . It is preferably stored with an area application of 0.25 to ² ^{g / m 2} and particularly preferably with an area application of 0.5 to 1.5 g / m 2.

As already mentioned above, the impregnation agent essentially comprises an impregnation resin, but can also contain other components components - for example to modify the processing and / or the properties of the molding material - such as hardeners, catalysts, thinners, additives, fillers, etc. include.

A suitable impregnating resin in the impregnating agent contains a cationically polymerizable monomer and / or oligomer. In particular, a suitable impregnating resin contains one or more anhydride-free compound (s) with oxirane and / or epoxy groups. These compound (s) can be wholly or partly aromatic, aliphatic and / or cycloaliphatic.

The following compounds may be mentioned as suitable impregnating resins alone or in mixtures, polymeric blends and copolymers:

- Epoxy resin, in particular bisphenol A and / or bisphenol F epoxy resin,

- novolaks

- Aliphatic epoxy resins

- Cycloaliphatic epoxy resins

- Glycidyl ether and / or glycidyl ester compound (s) of the aforementioned resins and

- Any mixtures, blends, copolymers of the aforementioned resins.

In particular, mixtures of cycloaliphatic epoxy resins with aromatic glycidyl ether epoxy resins are suitable impregnating resins for the purposes of the present invention.

According to an advantageous embodiment, a mixture of at least one 3,4-

Epoxycyclohexylmethyl-3 ', 4'-epoxycyclohexa-carboxylate with an aromatic epoxy resin, for example a bisphenol A and / or F-di-glycidyl ether.

As an example of a formulation of an impregnating resin, a mixture of aliphatic and / or aromatic epoxy resin with at least one cyclo-aliphatic epoxy resin is used specified. The mixing ratio of aliphatic and / or aromatic to cyclo-aliphatic epoxy resin can assume values in the range from 80:20 to 5:95 - each expressed as a percentage by weight. Preferred mixing ratios are in the range from 50:50 to 10:90, and preferably in the range from 30:70 to 15:85.

The advantages of a belt accelerator according to the invention in connection with an anhydride-free impregnating agent are also shown below with reference to figures, the measurements on exemplary belt accelerators according to the present invention, also in comparison to compounds according to the prior art also in connection with anhydride -free impregnating agents, show.

The extent of the reactivity of a belt accelerator with the structural formula I in areas of low belt accelerator concentrations during potting can also be demonstrated using DSC measurements, as will be shown below.

For the thermal stability of the belt accelerator according to structure I.

The band accelerator of structure I is a band accelerator that is cationically effective.

There are already cationically effective belt accelerators, for example based on quaternary ammonium compounds, be known, but these have the disadvantage of low thermal stability, even at temperatures well below 100 ° C, i.e. noticeable decomposition at processing temperatures of 50 ° C to 70 ° C. This is generally at least disadvantageous for use in the production of insulation systems, because temperatures of around 70 ° C can occur during the production of the solid insulation material and also when the conductor is heated before pressure impregnation and before contact with the impregnation agent. In contrast, the belt accelerator according to structure I has the advantage that it shows no significant change even after a temperature treatment of 168 hours at 70.degree. This can also be proven again by means of DSC measurements. The belt accelerator according to structure I is a white, crystalline solid at room temperature, the melting point of which can be determined by means of DSC. If the belt accelerator according to structure I changes and / or decomposes as a result of a temperature treatment, this would result in a lowering of the melting point.

Figures 4 and 5 show the results of the corresponding tests.

FIG. 4 shows a sample of the belt accelerator according to structure I at room temperature with a melting point of 160 ° C. known from the literature.

FIG. 5 shows the same sample after a temperature treatment of 168 hours at 70.degree. Melting point unchanged.

FIG. 6 again shows the same sample which, after the measurement that can be seen in FIG. 5, was subjected to a temperature treatment for a further 24 hours at 80.degree. Melting point still unchanged.

As FIGS. 4 to 6 impressively show, the tape accelerator according to structure I can withstand the temperature loads that occur during the production of a winding tape insulation and during the preparations for impregnation with impregnating agent, unchanged.

On the one hand, the compound withstands the temperature loads unchanged; on the other hand, an ionic compound composed of a sulfonium-containing cation with a hexafluoroantimonate anion, shown here using the example of the compound according to structure I, also retains its reactivity towards the Impregnation resin, such as the cycloaliphatic celloxide 2021P:

FIGS. 7 and 8 show a concentration of less than 1% by weight of belt accelerator in a typical impregnation resin, here a cycloaliphatic epoxy resin. FIG. 7 shows the reactivity of the fresh strip accelerator and FIG. 8 shows the reactivity in comparison therewith after a temperature treatment as in FIG. 6, i.e. the same strip accelerator after 168 hours of storage at 70 ° C and 24 hours at 80 ° C: also the reactivity, as before, the melting point of the compound used remains unchanged.

For comparison, the same tests were made with a quaternary ammonium hexafluoroantimonate as the belt accelerator.

The N- (p-methoxybenzyl) -N, N-dimethylanilinium hexafluoroantimonate is also a white, crystalline solid when fresh, like the sulfonium hexafluoroantimonate tested in FIGS. 3 to 8.

FIG. 9 shows the DSC measurement for determining the melting point of the fresh N- (p-methoxybenzyl) -N, N-dimethylanilinium hexafluoroantimonate. A peak at 116 ° C, which indicates the melting point, is clearly visible.

FIG. 10 shows the same sample after a temperature treatment of 48 hours at 70.degree. The spectrum has clearly changed, so the substance is no longer in its original state. A peak at 109 ° C proves the lowering of the melting point due to contamination. FIG. 11 shows the same measurement of the same sample after a temperature treatment of 168H at 70.degree. It is clear that there is no longer any detectable melting point.

For comparison with Figures 7 and 8, the reactivity of the comparative sample of the prior art, the N- (p-methoxybenzyl) -N, N-dimethylanilinium hexafluoroantimonate was determined compared to the cycloaliphatic epoxy resin, the Celloxide 2021P, as measured in the tests shown in FIGS. 7 and 8.

The result is again very clear because FIG. 12 shows sufficient reactivity of the system with the fresh N- (p-methoxybenzyl) -N, N-dimethylanilinium hexafluoroantimonate, the comparison with the N- (p- Methoxybenzyl) -N, N-dimethylanilinium hexafluoroantimonate turns out to be considerably less favorable in terms of reactivity and - as Figure 13 shows, the curing reaction of the belt accelerator stored for 168 hours at 70 ° C is according to the prior art, the N- (p-methoxybenzyl) -N, N- dimethylanilinium hexafluoroantimonate greatly reduced.

In the following, some additional tests are used to impressively demonstrate the properties and / or advantages of the cationic belt accelerator based on a sulfonium cation, in particular a dialkyl-aryl-sulfonium cation, compared to a common impregnating resin mixture of aromatic diglycidyl ether epoxy resin - for example the EP162 - and cycloaliphatic epoxy resin - for example the C2021P- shows.

Of the two resin components, preference is given to using those which, when mixed, produce mixtures with as low a viscosity as possible, because the impregnation and / or saturation of the solid insulation material is particularly successful in this way.

Table 2 shows the viscosities of mixtures of commercially available epoxy resins at temperatures from 50 ° C to 70 ° C:

Table 2:

FIG. 14 shows the graphic representation of Table 2. The decreasing viscosity with increasing temperature can be clearly seen.

Various concentrations of tape accelerator were added to these mixtures of impregnating resin. The cationic belt accelerator in accordance with a preferred embodiment of the present invention is referred to herein as "SI-150", a trade name under which the compound

"4-Acetyloxyphenyl-dimethylsulfonium hexafluoroantimonate" is available, reproduced.

By varying the concentration of belt accelerator, the impregnation resin composition and the impregnation temperature, the reactivity and / or the gel time and the sensitivity to low belt accelerator concentrations can be controlled.

Tables 3 to 5 show the results of setting the gel time via the belt accelerator concentration and / or the impregnating resin composition and / or the temperature.

Tables 3 to 5: FIG. 15 shows the gel times of mixtures of EP162 and C2021P at 70 ° C. as a function of the concentration of SI-150. The gel time increases with increasing content of tape accelerator, but also at a very low concentration of 0.1% A clear gelation can still be seen in the belt accelerator, so that even such low concentrations of the belt accelerator according to an exemplary embodiment of the invention are sufficient to achieve a stable insulation system. In contrast, FIG. 16 shows the gel times at the same concentration of belt accelerator, but at different temperatures and different mixing ratios in the impregnation resin. Here, too, clearly recognizable that at a low concentration of 1% SI-150 with different concentrations of cyclo-aliphatic epoxy resin in the mi emulsion of the impregnating resin, good gel times at 60 ° C and 70 ° C can be achieved.

Finally, FIG. 17 shows the gel times of mixtures of 20% EP162 and 80% C2021 with different concentrations of belt accelerator as a function of temperature.

The tests described above were all performed with the tape accelerator than a joint. However, it was completely surprising that it was recognized that a mixture of the belt accelerator component can also bring about a significant reduction in gel times.

The following gel times are obtained by adding another cationic sulfonium hexafluoro antimonate compound, benzyl (4-hydroxyphenyl) - methyl sulfonium hexafluoro antimonate, hereinafter abbreviated as SI-100 - to the belt accelerator SI-150 , which are summarized in Table 6:

Table 6:

The reactivity and / or sensitivity of the impregnating resin mixture with the belt accelerator mixture can be adjusted via the composition of the impregnation resin. It could be shown, completely surprisingly, that with an increasing proportion of cyclo-aliphatic epoxy resin in the impregnation resin composition, the reactivity of the belt accelerator SI-150 increases even at such low concentrations Belt accelerator such as 0.001% is still hardenable.

This is summarized in Table 7: Table 7:

FIGS. 18 to 21 show the curing reactions with various blends in the impregnating resin at belt accelerator concentrations as low as 1%, 0.1%, 0.01% and finally 0.001% of belt accelerator. It can be clearly seen in the graph above that with increasing content of cycloaliphatic epoxy resin C2021P, complete curing also occurs significantly at a content of belt accelerator of 0.001.

Mixtures with a proportion of 70% or more of cyclo-aliphatic epoxy resin, such as, for example, the C2021P, are particularly suitable for as complete a curing as possible in the complete mica tape insulation.

Finally, the properties of the tape accelerator in combination with tape adhesives were investigated.

In the solid insulation material, for example in the mica tape, the tape adhesive, for example, connects the particles of the mica platelets to one another to form a tape that ideally shows storage stability for at least 3 months, better still for 6 months or longer.

Storage stability is understood to mean that, on the one hand, there is constancy in their processing behavior. These can - for example in the case of a belt - be checked via a change in its flexural strength.

The change in flexural rigidity was measured and the results are shown in Tables 8 and 9 and in FIGS. 22 and 23.

Aromatic glycidyl ether epoxy resins, for example bisphenol A diglycidyl ether or epoxidized novolaks, are conventionally used as mica tape tape adhesives. When using sulfonium cations with hexafluoro antimonate as a tape accelerator, these tape adhesives are only suitable to a limited extent. This can be traced back to the storage stability of the solid insulation materials formed accordingly. The storage stability can be seen by measuring the flexural rigidity.

For example, a conventional solid insulation material that has been treated with a belt accelerator according to the invention, for example the SI-150, in an area application of 1 g per meter, increases its flexural strength by more than 50% after just 4 weeks at 40 ° C. A comparison sample of the same solid insulation material, which was not treated by applying Si-150 to the surface, did not show any increase in flexural rigidity.

The bending stiffness is a measure of the workability of the solid insulation material and is desirably as small as possible - for example for the production of a winding. In general, bending stiffnesses of more than 70 to 75 N per meter are seen as borderline for processing.

Table 8 shows the comparison of the two mica tapes Poroband 4037 from Isovolta, once with subsequent application of SI-150, once without.

Table 8:

Tests have shown that tape adhesives without epoxy groups, such as thermoplastic polyvinyl acetals, especially when acetalized with butyraldehyde and / or acetaldehyde) and / or liquid polyesters with hydroxy and / or carboxy groups, do not show any significant edges increase in flexural rigidity with the same aftertreatment with SI-150.

For example, a mixture of the polyvinyl acetal Mowital® BA55HH from Kuraray and the carboxy-functional polyester polyol Rokrapol 7075 from Robert Kraemer can be used to formulate a tape adhesive that has properties comparable to conventional epoxy-containing tape adhesives, but in combination with SI-150 shows significantly better storage stability.

A mica tape sample of the composition;

- 12.25 g / nr ² Rokrapol 7075

- 2.00 g / nr ² Mowital BA55HH

- 1.00 g / nr ² SAN-AID SI-150 shows only an increase in flexural rigidity of 14% after storage for 4 weeks at 40 ° C. The absolute value of 70-75 N / nr ² is also not exceeded.

Table 9 shows the corresponding measurement results: Table 9:

Change in belt accelerator activity and / or reactivity

A further measure of the storage stability of strip accelerator-containing mica strips is the constancy of the strip accelerator activity and / or reactivity.

This can be recorded using DSC. For this purpose, the reaction exothermicity of a mica tape sample of 19-25 mm ² with 8-9 mg of impregnating resin is measured in the DSC.

A mica tape sample of the composition;

- 12.25 g / nr ² Rokrapol 7075

- 2.00 g / nr ² Mowital BA55HH

- 1.00 g / nr ² SAN-AID S1-150 shows after storage for 4 weeks at 40 ° C no significant change in the reaction exotherm and in the peak maximum compared to a mixture of 20% EP162 and 80% C2021 P as Impregnation resin.

FIG. 22 shows the hardening reaction of a mixture of 20% EP162 and 80% C2021P against a mica tape with a tape accelerator application of 1 g / nr ² of SI-150, the mica tape sample not having been thermally post-treated. FIG. 23 shows the hardening reaction of a mixture of 20% EP162 and 80% C2021P against a mica tape with a tape accelerator application of 1 g / nr ² of SI-150, the mica tape sample being stored thermally at 40 ° C. for 4 weeks.

Properties and advantages of the belt accelerator in combination with mica belt and anhydride-free impregnation resins With regard to the accelerator range:

The range of the band accelerator out of the mica band can be shown in a simple experiment. For this purpose, a mica tape sample measuring 400x25mm is wound onto a 4mm thick mandrel. The resulting roll is removed from the mandrel and placed in front of the curvature of the bottom of a test tube using tweezers. Then 4.4 g of preheated impregnation resin - e.g. 70 ° C - are added. The impregnating resin slowly penetrates the roll, so that the curvature of the bottom and the gusset in the roll are also filled. A resin protrusion of ~ 10mm remains.

The roll prepared in this way is then subjected to the hardening program in the convection oven and then assessed for complete hardening, especially on the bottom, gusset and protrusion as well as the roll itself.

A mica tape sample of the composition;

- 12.25 g / nr ² Rokrapol 7075

- 2.00 g / nr ² Mowital BA55HH

- 1.00 g / nr ² SAN-AID S1-150 shows with a mixture of 20% EP162 and 80% C2021 P as impregnation resin in this test a complete hardening of the roller and all resin areas.

Finally, the dielectric properties were measured to determine suitability in the insulation system: The electrical performance of such a mica tape in combination with an anhydride-free impregnating resin based on epoxy resin is also given. So a mica tape of the composition provides:

- 12.25 g / nr ² Rokrapol 7075

- 2.00 g / nr ² Mowital BA55HH

- 1.00 g / nr ² SAN-AID Sl-150 in combination with a mixture of 20% EP162 and 80%

C2021P as the impregnating resin after curing for 10 h / 145 ° C, an insulation system with a low electrical loss factor tan d over a temperature range from room temperature to 155 ° C, as shown in FIG.

Figure 24 shows the course of the temperature-dependent loss factor tan d of an insulation system from a mica tape sample according to an embodiment of the present invention with a tape accelerator application of 1g per meter, impregnated and soaked with an impregnating agent, a mixture of 20% EP162 and 80 % C2021P comprising after a final curing of 10 hours at 145 ° C.

The invention provides for the first time a solid insulation material with a tape accelerator and, optionally, a suitable tape adhesive, which can be quickly and completely treated with anhydride-free impregnating agent, even in areas with little tape accelerator, under the conditions of vacuum pressure, for example. Impregnation -VPI - provides a stable insulation system with a low number of imperfections.

Claims

1. Cationic belt accelerator for use in a process for the production of an insulation system by impregnation and / or encapsulation with an anhydride-free impregnating agent, which is an ionic compound of one or more sulfonium-containing cation (s) with one or more hexafluoroantimonate anions ( en).

2. Belt accelerator according to claim 1, in which at least one aryl-alkyl-sulfonium cation is present as the sulfonium-containing cation.

3. Belt accelerator according to one of claims 1 or 2, in which at least one di-alkyl-aryl-sulfonium and / or a di-aryl-alkyl-sulfonium is present as the sulfonium-containing cation.

4. Belt accelerator according to one of the preceding claims, in which a substituted aryl radical is present in at least one type of sulfonium-containing cation.

5.Band accelerator according to claim 4, wherein the Arylgrup pe comprises a phenyl ring which is acetyloxy-substituted.

6. Belt accelerator according to one of the preceding claims, which has the following chemical structure:

Structure i

7.Use of a belt accelerator according to one of claims 1 to 6 for the production of an anhydride-free insulation system by impregnating the solid Isolati onswerkstoffes with an impregnating agent, the impregnating agent comprising an aromatic and / or cycloaliphatic impregnating resin that is anhydride-free and Contains epoxy groups.

8. Solid insulation material, a barrier material, egg NEN tape adhesive and a tape accelerator in the form of a compound according to any one of claims 1 to 6 comprising.

9. Solid insulation material according to claim 8, wherein the barrier material is in the form of platelets.

10. Solid insulation material according to claim 8 or 9, further comprising a carrier.

11. Solid insulation material according to claim 10, wherein this carrier comprises a woven fabric, a fleece, a film and / or a perforated film.

12. Solid insulation material according to one of claims 8 to 11, a tape adhesive in the form of a thermoplastic polyvinyl acetal and / or a liquid polyester, which can include hydroxyl groups and / or carboxy groups, before.

13. Solid insulation material according to claim 12, comprising a tape adhesive in the form of a polyvinyl acetal based on butyraldehyde and / or acetaldehyde.

14. Isolation system, comprising an impregnated with an anhydride-free impregnating agent winding of a solid Iso lationswerkstoffes according to any one of the preceding claims 8 to 11.

15. Electrical machine comprising an insulation system according to claim 14.

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