Process for impregnating electric coils and epoxy resin compositions suitable for the impregnating process

The present invention relates to a process for impregnation of an electrical coil, a winding of several layers, one of which each of more than one Winding an electrically conductive material consists drahfförmigen, with a plastic material, the the einzelen turns of drahfförmigen material electrically from each other isolated, in which the individual turns of the coil by means of a curable epoxy resin composition be wrapped and this composition is cured thermally is, and particularly preferred curable compositions for carrying out the Impregnation.

From WO-A-96/01481 is known curable epoxy resin compositions, which in Room temperature are liquid and (a) a liquid Bisphenol A diglycidyl ether, (b) a Cross-linking agent therefor, (c) a suitable accelerator for the reaction of the liquid include diglycidyl ether (a) with the crosslinking agent (b) and (d) a filler material, that the component (a) and (b), 40 to 60 weight percent based calcite and comprises acicular wollastonite artificial, for impregnating and possibly to to use wrapping of electrical coils, the windings of many layers comprise any of a large number of turns of one of those thin drahfförmigen conductor material, such. as the secondary windings of transformers or ignition coils. The use of liquid epoxy resin systems, such as the said, while allowing the sufficient impregnation of such windings, ie the penetration of the epoxy material between all turns of a winding, but does not a few drawbacks. Thus, the liquid epoxy resin systems can only in two-component form be made up, what the processing overhead is not negligible for the user enlarged. Furthermore, the said liquid require the lmprägnierungssysteme Use of a lost form of the desired for the finished coil outer Contour. In this form the coil to be wrapped has to be introduced. Then you have the Form, in general, after evacuation, with the liquid curable epoxy resin composition be filled and cured the composition in the form will. After curing, the mold can not be enffernt, and must therefore remain as "lost form" forever around the coil. Another very is essential disadvantage of the above-mentioned liquid epoxy resin Moreover, their extremely long curing time, which is generally several hours and the case of mass production of coils using huge curing ovens necessary power.

Object of the present invention, including the above-mentioned drawbacks is at impregnation of coils, especially coils, transformers and Print Flybacktransformatoren to avoid.

It has now been found that for the impregnation of such coil even at room temperature, ie at a temperature of about 15 to 25 ° C fixed, below in specific defined way composite, preferably fiber reinforced, curable epoxy resin compositions can be used. Especially surprising here, that such compositions, the secondary windings of conventional ignition coils and can penetrate transformers sufficiently, even if they are relatively contain large amounts of a reinforcing material of inorganic fiber Length of up to about 2.5 mm exists. The use of this solid epoxy resin makes the use of the lost forms unnecessary and reduces the the completion of the coil sheath required curing many times in the range of a few minutes, generally of a maximum of 15 minutes.

The present invention in its broadest sense is a process for the Impregnation of an electrical coil comprising a winding of several layers comprises from more than one turn of electrically conductive material drahfförmigen, with a plastic material that the einzelen turns of drahfförmigen material electrically isolated from each other by means of a thermally curable epoxy resin composition, characterized in that this composition solid at room temperature is and shall contain the following ingredients:<sl><li>(A) a solid epoxy resin at room temperature, selected from<sl><li>(A1) polyglycidyl ethers based on novolaks;</li><li>(A2) diglycidyl ethers based on bisphenols and</li><li>(A3) mixtures of more than one of the components (a1) and (a2);</li></sl></li><li>(B) a crosslinking agent for the component (a);</li><li>(C) a suitable accelerator for the reaction of the component (a) and the Component (b);</li><li>(D) 15 to 70 weight percent, based on the total weight of the composition, Filler selected from<sl><li>(D1) of calcium carbonate, </li><li>(D2) quartz flour,</li><li>(D3) wollastonite, whose particles have an average ratio of length to have cross-section that is less than 5: 1;</li><li>(D4) mixtures of the components (d1), (d2) and (d3) and</li><li>(D5) mixtures of the components (d1), (d2), (d3) and (d4) with other inorganic fillers.</li></sl></li></sl>

Under "impregnation" is in this application a treatment of the electrical coil understood, in which the individual turns of at least one coil winding with the help of curable epoxy resin are coated and the composition is thermally cured. This treatment, however, the entire envelope of parts of the coil or of the entire coil, inclusive of the bobbin, with the curable Epoxy resin include.

Preferably comprises the composition in the inventive process is used, further comprising:<sl><li>(E) 10 to 60 weight percent, based on the total weight of the composition, inorganic reinforcing agent in the form of needle-like or fibrous Particles having a length of 0.05 to 2.5 mm, which have an average ratio of length to cross-section of 5: 1 and more exhibit,</li></sl>wherein the total amount of component (d) and (e) up to 80 weight percent, based on the total weight of the composition ratio, is.

Preferably specially selected compositions are used, in which the reinforcing agent (e) from acicular or fibrous particles having a length of 0.15 is up to 2.5 mm. These compositions form a further aspect of the present invention.

Particularly preferably it is in the reinforcing agent (e) to a glass fiber material, in particular, milled or chopped glass fibers having a length of 0.05 to 2.5 mm and a diameter of preferably 10 to 30 microns, in various Form are also commercially available. Particularly good results have, for example, Reinforcing material of glass fibers of a length of 0.05 mm, in particular of 0.15 mm to 2 mm, especially to 1 mm, for example from about 0.2 to 0.25 mm.

In the case of polyglycidyl ethers based on novolaks, according to the invention in which Process and in the novel compositions as component (a1) to Be used, there are in particular:<sl><li>(A1.1) polyglycidyl ethers based on epoxy phenol novolacs,</li><li>(A1.2) polyglycidyl ethers based on Epoxycresolnovolaken or</li><li>(A1.3) mixtures of epoxy novolaks of the type (a1.1) and / or (a1.2).</li></sl>

In the (a2) component is preferably diglycidyl ethers based on Bisphenol A. This can for example also be pre-extended (advanced) resins by reacting Bisphenol A diglycidyl ether with a substoichiometric available from substances are, the two reactive with epoxide functional groups comprise, in particular, by reacting from 1.1 to 2 moles of bisphenol-A diglycidyl ether with one mole of bisphenol A.

The crosslinking agent (b) is suitably selected from:<sl><li>(B1) dicyandiamide,</li><li>(B2) polycarboxylic acid anhydrides and</li><li>(B3) mixtures of more than one of the components (b1) and / or (b2) and / or one or more polyphenols.</li></sl>

Is an organic carboxylic acid anhydride used as the crosslinking agent, it is preferably to an aromatic or cycloaliphatic polycarboxylic acid anhydride to a in particular to a corresponding dicarboxylic acid such. B. Phthalic anhydride, hexahydrophthalic or methyltetrahydrophthalic. are particularly preferred solid at room temperature carboxylic anhydrides.

Containing the crosslinking agent a certain proportion of polyphenols, this can be advantageous in Relation to the processing of his lmprägniermassen. Since the presence of large Amounts of polyphenols, however, the penetration of the curable composition in the may complicate winding, thus reducing the impregnation depth, is directed the Upper limit for the proportion of polyphenols in the crosslinking agent after the required lmprägniertiefe.

When polyphenols are preferred:<sl><li>phenol novolaks,</li><li>Cresol novolaks and / or </li><li>Mixtures of novolaks of the types mentioned.</li></sl>

The crosslinking agent (b) is used in the amounts conventionally used, eg. B. in amounts up to 50 weight percent, preferably up to 25 weight percent, based on the epoxy resin. Dicyandiamide is especially preferred in an amount from 0.16 to 0.5 Mol used per epoxide of the composition, in particular are you there in such quantities that in the novel compositions 0.25 to 0.35 Mole dicyandiamide are present per epoxide equivalent.

When dicyandiamide is used as crosslinking agent, the present invention Epoxy resin particularly good latency, so that, for example, without problems at room temperature (about 15 to 25 ° C) can be stored.

Accelerators (d) All known to the skilled worker for accelerating Reaction of epoxy resins with dicyandiamide or polyphenols, or with organic anhydrides usual substances. examples for Accelerators for the reaction with dicyandiamide are alkali metal alcoholates, tertiary amines, hexamethylenetetramine in particular, phosphines such as triphenylphosphine, quaternary, Ammonium compounds, substituted ureas, such as N- (4-chlorophenyl) -N, N'-dimethylurea or N- (3-chloro-4-methylphenyl) -N, N'-d imethylharnstoff, Mannich bases, such as 2,4,6-tris (dimethylaminomethyl) phenol or 2,4,6-tris- (diethylaminomethyl) phenol, imidazole or imidazole derivatives such as 2-phenylimidazole, 2-ethylimidazole, 2-methylimidazole or Benzimidazole, and BCl₃- And BF₃Complexes with tertiary amines, such as trimethylamine, Octyldimethylamine, triethylamine, piperidine, pyridine or hexamethylenetetramine. Prefers are imidazoles, especially 2-ethylimidazole. Examples of accelerators for the reaction with polyphenols are tertiary amines such as benzyldimethylamine, imidazoles such as imidazole, 2-phenylimidazole, 2-ethylimidazole, 2-methylimidazole or benzimidazole, or quaternary Ammonium compounds. Examples of accelerators for the reaction with Carboxylic anhydrides are tertiary amines and their salts, such as N-benzyldimethylamine or triethanolamine, Mannich bases, as already mentioned above, and imidazole Imidazole derivatives, quaternary ammonium salts, for. Example, benzyltrimethylammonium chloride, Phosphonium salts such as tetraphenylphosphonium, and alkali metal. The Amount of accelerator is preferably 1 to 30 parts by weight, based on 100 Parts by weight of catalyst, more preferably 3 to 20 parts by weight, especially 5 to 12 parts by weight.

The particle size distribution of the filler which is the component (d) described forming compositions, preferably from 0.1 to 200 microns, especially 0.2 to 60 microns. Wherein the calcium carbonate used as a filler it is preferably finely divided and substantially anhydrous calcium carbonate. Examples of other inorganic fillers as calcium carbonate, quartz powder and wollastonite are kaolin, Dolomite, barium sulfate, talc, mica, alumina or alumina trihydrate. Will Mixtures of calcium carbonate, quartz flour and / or wollastonite with other fillers is used, the compositions contain preferably at least 20, in particular at least 30 weight percent calcium carbonate, quartz flour and / or wollastonite. The other fillers can be, for. example in an amount of up to 40, preferably in an amount be present up to 30 weight percent. Particular preference is given in accordance with the invention compositions employed wollastonite as the only filler.

Moreover, in some cases, it proves advantageous if the compositions erfindundungsgemäss be used, a toughening agent as another Component (F). The toughening agent is here preferably in quantities of 0.5 to 5, preferably in the range of about one to two percent by weight, based on the Total composition.

The toughening agent (f) is preferably selected from:<sl><li>(F1) with polysiloxanes modified epoxy resins and</li><li>(F2) block copolymers, based on polydimethylsiloxanes and caprolactone or Polycaprolactones.</li></sl>

Such tougheners are known in the art and in various forms also commercially available.

If a toughening agent of type (f1) used, it is in particular a modified polysiloxanes diglycidylether based on bisphenol A.

The inventively used for impregnating electrical coils Compositions may further comprise a mold release agent as a further component (g) contain such. B. Hoechst OP Wachs® (partially hydrolyzed montan wax), Hoechst-Wachs KSL ® (lignite wax), carnauba wax, calcium stearate or similar mold release agents or Mixtures of one or more of the substances mentioned.

Furthermore, the curable compositions according to the invention employed can still contain further conventional additives, for. example, coupling agents for the fillers and the Reinforcing materials such as in particular silane coupling agents, pigments such as carbon black, or Plasticisers.

In a specific embodiment of the inventive method, a used curable composition comprising as components (a), (b) and (c) listed below components:<sl><li>(A2) one or more diglycidyl ethers based on bisphenols;</li><li>(B2) one or more polycarboxylic acid anhydrides;</li><li>(C) a suitable accelerator for the reaction of the component (a2) and the component (b2).</li></sl>

In a particularly preferred embodiment of the inventive method contains the composition used for coating of the coils as components (a), (B) and (c) the below-mentioned components:<sl><li>(A) a solid epoxy resin at room temperature, selected from<sl><li>(A1) one or more polyglycidyl ethers based on novolaks;</li><li>(A2) diglycidyl ethers based on bisphenols and in particular</li><li>(A3) mixtures of more than one of the components (a1) and (a2);</li></sl></li><li>(B) a crosslinking agent selected from<sl><li>(B1) dicyandiamide and</li><li>(B4) mixtures of dicyandiamide and polyphenols (b2); and</li></sl></li><li>(C) a suitable accelerator for the reaction of the component (a) and the selected component (b1) or (b4), z. B. hexamethylenetetramine.</li></sl>

In the latter embodiment of the method lmprägnierungssmassen with a particularly high Tg, generally above 150 ° C (determined by torsion pendulum according to ISO 6721, heating rate 2 ° C / min) is achieved.

In preferred specific variants of the latter embodiment of the inventively Encapsulant used is the component (a) is a polyglycidyl ether of Basis of a cresol novolak and / or the crosslinking agent (B) either dicyandiamide alone or a mixture of dicyandiamide and polyphenols, which is located at the Polyphenols, in particular phenol novolaks, cresol novolaks or mixtures of the mentioned novolaks is.

The preparation and homogenization of the curable inventively employed Compositions may, for. Example, in a conventional manner with the aid of known mixing equipment such as Ball mill, co-kneader, roll mill or extruder, optionally with melting of the Compositions, if necessary followed by a comminution of the molten Material carried. Of course, also suitable Combinations of the above homogenization apply. Likewise, it is possible, for example, the components of the curable Compositions to be dissolved in a suitable solvent and / or suspend and subsequently to evaporate the solvent, so that the homogenized composition in solid form remains.

For the impregnation of the coil is such, optionally after heating up, in a form introduced. Thereafter, the curable composition is in the coil-containing introduced therein form and under pressure, preferably at a possible low cavity pressure, for example of at most 100 MPa, for a time of for example up to a maximum of 10 min, preferably less than about 5 min thermally cured, preferably at temperatures in the range of 140 to 250 ° C, in particular of 160 to 200 ° C, more preferably in the range of about 180 ° C. The time pressure profile at Fill and the maximum pressure is dependent on the coil to be impregnated. The mentioned parameters can be determined experimentally in a simple manner by the skilled worker will.

Preferably, the mold is evacuated prior to introducing the curable composition and the curable composition in which the coil-containing evacuated form introduced. This is especially true for the currently used chamber windings.

That's lmprägnierungsverfahren inventive example for impregnation of coil turns having a winding density of up to 1000 turns per mm². preferably of up to 500 turns per mm², Suitable, and for the windings For example, wire diameters down to 20 microns, preferably to down 50 microns, can be used. The thickness of the entire windings can here be up to 5 mm z. B. up to 7.5 mm, preferably. Corresponding windings z. B. found in coils, transformers and Print Flybacktransformatoren.

Preferably carried out at the inventive impregnation process after Principle of a conventional pressing, transfer molding or injection molding process.

If an injection molding process used in this case, because of the comparatively low Melt viscosities of the curable compositions according to the invention employed preferably a cylinder set is used, the spray nozzle can be closed, so that the nozzle can be closed, for example, in an open form. Likewise Here the use of a screw be advantageous having a back flow valve.

Examples:

Fig. 1 shows a schematic representation of the pressing tool, with which the test coil in are impregnated in the following examples.

Fig. 2 shows a longitudinal section through the coil former used in the examples and its dimensions.

General procedure for preparation of impregnation masses

Glass fibers and / or fillers are admixed with a silane coupling agent and 30 minutes long vemahlen with a ball mill. If a toughening agent used, it is in the amount needed then also in a ball mill for 20 minutes by a filler ground. Finally, all components of the curable compositions, with Except the glass fibers, milled in a ball mill about for 4.25 hours. After that the glass fibers are added and it is again milled for 45 minutes. The so obtained powder are finally having a Huttverdichter to granules processed.

For the production referred to in the Examples lmprägnierungsmassen join the characterized below fillers, reinforcing materials and additives for use: <tables><table><tgroup cols="2"><tbody><row><entry align="left">tradename</entry><entry align="center">Chemical composition</entry></row><row><entry align="left">NYAD®200</entry><entry align="left">Natural wollastonite (200 mesh grade)</entry></row><row><entry align="left">NYAD®325</entry><entry align="left">Natural wollastonite (325 mesh grade)</entry></row><row><entry align="left">OMYA®BSH OMYA®BSH</entry><entry align="left">Natural, surface-coated calcium carbonate (particle size distribution from 0.1 to 20 microns; D₅₀ = 2.4 microns)</entry></row><row><entry align="left">Milled Glas®737BD (Owens Corning)</entry><entry align="left">Milled glass fibers (average length = 225 microns, ⊘ = 15 - 16 microns)</entry></row><row><entry align="left">Albidur®EP 2240</entry><entry align="left">Siloxane-bisphenol A epoxy resin</entry></row><row><entry align="left">Hoechst OP® wax 125u</entry><entry align="left">partially hydrolyzed montan wax</entry></row><row><entry align="left">Hoechst KSL® wax</entry><entry align="left">Montan wax</entry></row><row><entry align="left">Silane A 187®</entry><entry align="left">silane coupling agent</entry></row><row><entry align="left">Printex V®</entry><entry align="left">Soot</entry></row></tbody></tgroup></table></tables>

The performance properties of the lmprägnierungsmassen be in all Examples, unless otherwise specified, using the specified below Measurement methods determined:<sl><li><u>Tg</u>: Torsion pendulum according to ISO 6721</li><li><u>flexural strength</u>: ISO 178</li><li><u>flexural modulus</u>: ISO 178</li><li><u>impact strength</u>: ISO 179/1</li><li><u>Lin. therm. expansion coefficient α</u> : DIN 53752 (temperature range 20 - 80 ° C)</li></sl>

Impregnation, determine the depth of impregnation, the impregnation Beurteilunq:

The impregnation of the test coil is in all the examples according to the principle of transfer molding (Transfer molding), wherein the test apparatus is illustrated schematically in FIG. 1 for Applied. This contains two separable parts (1) and (6). The first Part (1) has a spray chamber (2) for accommodating a tablet (11), consisting of the inventive impregnation, the transfer piston (3), the cavity (4) and a bore (5) for receiving a temperature sensor. containing the second part (6) a core (7) for holding the to be impregnated coil (10), a device (8) for Removing the finished impregnated coil from the core (7) and a connection (9) for Evacuation of the cavity (4). A pre-heated to about 110 ° C coil (10) in FIG. 2 Dimensions indicated that in all chambers a coil of copper wire of a Diameter of 94 microns with a winding density of about 100 turns per mm² , said winding thickness of the top chamber to the bottom chamber of about 3.5 to about 5.5 mm increases, is in the cavity (4) of the heated to 180 ° C Imprägnierwerkzeugs (1.6) is introduced. The granulafförmige impregnating is cold compressed into a tablet and then with the aid of a Hochfrequenzvorwärmgerätes heated to about 70 ° C. The thus preheated tablet (11) is in the spray booth (2) are introduced and it is a vacuum of about 30 mbar is applied to the cavity. Thereafter, the lmprägniermasse with the aid of the piston (3) during a period of 15 s in the cavity (4) transferred (spraying pressure between 80 and 150 bar). The subsequent Curing time is 5 min. Thereafter, the coated and impregnated coil demolded. The removed coil is sawn and polished in the longitudinal direction. With help of a Microscope is the lmprägniertiefe reached each measure and the lmprägniergüte assessed visually. The impregnation should be regarded as "good" when more than 95 percent of Space between the wire turns of a winding with the lmprägniermasse filled are.

Crack resistance:

To determine the crack resistance, a test piece is prepared by reacting an sharp-edged, rectangular 60 mm long, 30 mm wide and 4 mm thick metal plates coated with the respective lmprägnierungsmasse, wherein the at the four corners Metal plate are each a range of about 8 mm by 8 mm is released, and the Mass cured at 170 ° C to 180 ° C. The thickness of the coating is about 3 mm in Direction of the longitudinal and of the broad side of the metal lamina and about 2 mm perpendicular thereto. The specimen is specified after the removal in the following table subjected sequence of treatment steps and after each treatment step to a Cracking in the encapsulant assayed for. Cracking class corresponds to the last treatment step, after which the specimen shows no cracking.<tables><table><tgroup cols="2"><tbody><row><entry align="center">step</entry><entry align="left">No cracking after</entry></row><row><entry align="center">1</entry><entry align="left">-</entry></row><row><entry align="center">2</entry><entry align="left">1 hour, leaving them at room temperature after removal from the mold</entry></row><row><entry align="center">3</entry><entry align="left">4 hours leaving them at room temperature after removal from the mold</entry></row><row><entry align="center">4</entry><entry align="left">24 hours, leaving them at room temperature after removal from the mold</entry></row><row><entry align="center">5</entry><entry align="left">Step 4 + cooling from room temperature to 0 ° C in ice water, 30 min at 0 ° C</entry></row><row><entry align="center">6</entry><entry align="left">Step 5 + 30 minutes at 100 ° C, cooling to 0 ° C in ice water, 30 min at 0 ° C</entry></row><row><entry align="center">7</entry><entry align="left">Step 6 + cooling from room temperature to -20 ° C, 15 min at -20 ° C</entry></row><row><entry align="center">8th</entry><entry align="left">Step 7 + cooling from room temperature to -40 ° C, 15 min at -40 ° C</entry></row><row><entry align="center">9</entry><entry align="left">Step 8 + cooling from 100 ° C to -40 ° C, 15 min at -40 ° C</entry></row><row><entry align="center">10</entry><entry align="left">Step 9 + cooling from 100 ° C to -60 ° C, 15 min at -60 ° C</entry></row></tbody></tgroup></table></tables>

Example 1:

According to the general method described above is a 1 kg prepared lmprägnierungsmasse following composition and studied:<tables><table><tgroup cols="2"><tbody><row><entry align="left">component</entry><entry align="center">weight percent</entry></row><row><entry align="left">Epoxy cresol novolac (epoxy value 4.3 eq / kg;. Kofler melting point 79 ° C)</entry><entry align="center">19,51</entry></row><row><entry align="left">Of advanced Bisphenol A diglycidyl ether (epoxide content about 1.7 eq / kg; Kofler melting point 55 - 65 ° C.)</entry><entry align="center">12,68</entry></row><row><entry align="left">Cresol (mp 97-104 ° C)</entry><entry align="center">0.99</entry></row><row><entry align="left">dicyandiamide</entry><entry align="center">2.7</entry></row><row><entry align="left">ZK 191.2-K chunks (accelerators based on o-cresol and 2-ethyl imidazole; Kofler melting point 60-70 ° C)</entry><entry align="center">0.2</entry></row><row><entry align="left">NYAD 200</entry><entry align="center">46,79</entry></row><row><entry align="left">Milled Glass 737 BD</entry><entry align="center">15,00</entry></row><row><entry align="left">Hoechst OP wax 125u</entry><entry align="center">1.7</entry></row><row><entry align="left">Silane A 187</entry><entry align="center">0.23</entry></row><row><entry align="left">Printex V</entry><entry align="center">0.2</entry></row></tbody></tgroup></table></tables>

The lmprägnierungsmasse has the following characteristics:<tables><table><tgroup cols="2"><tbody><row><entry align="left">property</entry></row><row><entry align="left">lmprägnierungstiefe [mm]</entry><entry align="center">3.5</entry></row><row><entry align="left">lmprägnierungsgüte</entry><entry align="center">Good</entry></row><row><entry align="left">Tg [° C]</entry><entry align="center">170</entry></row><row><entry align="left">Flexural strength [MPa]</entry><entry align="center">110</entry></row><row><entry align="left">Flexural modulus [MPa]</entry><entry align="center">14600</entry></row><row><entry align="left">Impact strength [kJ / m²]</entry><entry align="center">6</entry></row><row><entry align="left">crack resistance</entry><entry align="center">7</entry></row><row><entry align="left">Lin. therm. expansion coefficient α [K^-1]</entry><entry align="center">33.10^-6</entry></row></tbody></tgroup></table></tables>

Example 2:

According to the general procedure described above, 1 kg of another lmprägnierungsmasse with the following composition: <tables><table><tgroup cols="2"><tbody><row><entry align="left">component</entry><entry align="center">weight percent</entry></row><row><entry align="left">Epoxy cresol novolac (epoxy value 4.3 eq / kg;. Kofler melting point 79 ° C)</entry><entry align="center">33.0</entry></row><row><entry align="left">dicyandiamide</entry><entry align="center">4.0</entry></row><row><entry align="left">ZK 191.2-K chunks (accelerators based on o-cresol and 2-ethyl imidazole; Kofler melting point 60-70 ° C)</entry><entry align="center">0.2</entry></row><row><entry align="left">NYAD 200</entry><entry align="center">43.9</entry></row><row><entry align="left">Milled Glass 737 BD</entry><entry align="center">15.0</entry></row><row><entry align="left">Albidur® EP 2240</entry><entry align="center">2.0</entry></row><row><entry align="left">Hoechst KSL-Wax</entry><entry align="center">1.7</entry></row><row><entry align="left">Silane A 187</entry><entry align="center">0.2</entry></row></tbody></tgroup></table></tables>

This lmprägnierungsmasse has the following characteristics:<tables><table><tgroup cols="2"><tbody><row><entry align="left">property</entry></row><row><entry align="left">lmprägnierungstiefe [mm]</entry><entry align="center">5.5</entry></row><row><entry align="left">lmprägnierungsgüte</entry><entry align="center">Good</entry></row><row><entry align="left">Tg [° C]</entry><entry align="center">≈200</entry></row><row><entry align="left">Flexural strength [MPa]</entry><entry align="center">135</entry></row><row><entry align="left">Flexural modulus [MPa]</entry><entry align="center">11600</entry></row><row><entry align="left">Impact strength [kJ / m²]</entry><entry align="center">7</entry></row><row><entry align="left">Lin. therm. expansion coefficient α [K^-1]</entry><entry align="center">33.10^-6</entry></row></tbody></tgroup></table></tables>

Example 3:

According to the protocol described above is one kilogram a lmprägnierungsmasse with the following composition:<tables><table><tgroup cols="2"><tbody><row><entry align="left">component</entry><entry align="center">weight percent</entry></row><row><entry align="left">Of advanced Bisphenol A diglycidyl ether (epoxide content about 1.7 eq / kg; Kofler melting point 55 - 65 ° C.)</entry><entry align="center">31.7</entry></row><row><entry align="left">phthalic anhydride</entry><entry align="center">5.2</entry></row><row><entry align="left">BCl₃N (CH₃)₃-Complex</entry><entry align="center">0.3</entry></row><row><entry align="left">NYAD 325</entry><entry align="center">40.4</entry></row><row><entry align="left">OMYA BSH</entry><entry align="center">19.0</entry></row><row><entry align="left">Albidur® EP 2240</entry><entry align="center">2.0</entry></row><row><entry align="left">Hoechst KSL-Wax</entry><entry align="center">1.4</entry></row></tbody></tgroup></table></tables>

This lmprägnierungsmasse has the following characteristics:<tables><table><tgroup cols="2"><tbody><row><entry align="left">property</entry></row><row><entry align="left">lmprägnierungstiefe [mm]</entry><entry align="center">5.5</entry></row><row><entry align="left">lmprägnierungsgüte</entry><entry align="center">Good</entry></row><row><entry align="left">Tg [° C]</entry><entry align="center">≈120</entry></row></tbody></tgroup></table></tables>

A complete impregnation of good lmprägnierungsgüte is with the above in the Examples mentioned lmprägnierungsmassen also achieved if instead of in the Examples impregnated test winding (Test), for example, in the following table mentioned windings A, B and C impregnated:<tables><table><tgroup cols="4"><tbody><row><entry align="center">winding</entry><entry align="center">Wire diameter [.mu.m]</entry><entry align="center">Winding density [1 / mm²]</entry><entry align="center">Winding thickness [mm]</entry></row><row><entry align="center">test</entry><entry align="center">94</entry><entry align="center">100</entry><entry align="center">3.5 - 5.5</entry></row><row><entry align="center">A</entry><entry align="center">61</entry><entry align="center">180</entry><entry align="center">0.95</entry></row><row><entry align="center">B</entry><entry align="center">40</entry><entry align="center">465</entry><entry align="center">3.5</entry></row><row><entry align="center">C</entry><entry align="center">65</entry><entry align="center">254</entry><entry align="center">3</entry></row></tbody></tgroup></table></tables>

Example 4:

According to the general method described above is a 1 kg prepared lmprägnierungsmasse following composition and studied:<tables><table><tgroup cols="2"><tbody><row><entry align="left">component</entry><entry align="center">weight percent</entry></row><row><entry align="left">Epoxy cresol novolac (epoxy value 4.3 eq / kg;. Kofler melting point 79 ° C)</entry><entry align="center">19,50</entry></row><row><entry align="left">Of advanced Bisphenol A diglycidyl ether (epoxide content about 1.7 eq / kg; Kofler melting point 55 - 65 ° C.)</entry><entry align="center">12,68</entry></row><row><entry align="left">Cresol (mp 97-104 ° C)</entry><entry align="center">1.00</entry></row><row><entry align="left">dicyandiamide</entry><entry align="center">2.7</entry></row><row><entry align="left">hexamethylenetetramine</entry><entry align="center">0.2</entry></row><row><entry align="left">NYAD 200</entry><entry align="center">46,79</entry></row><row><entry align="left">Milled Glass 737 BD</entry><entry align="center">15,00</entry></row><row><entry align="left">Hoechst OP wax 125u</entry><entry align="center">1.7</entry></row><row><entry align="left">Silane A 187</entry><entry align="center">0.23</entry></row><row><entry align="left">Printex V</entry><entry align="center">0.2</entry></row></tbody></tgroup></table></tables>

The lmprägnierungsmasse has the following characteristics:<tables><table><tgroup cols="2"><tbody><row><entry align="left">property</entry></row><row><entry align="left">lmprägnierungsgüte</entry><entry align="center">Good</entry></row><row><entry align="left">Tg [° C]</entry><entry align="center">160</entry></row><row><entry align="left">Flexural strength [MPa]</entry><entry align="center">130</entry></row><row><entry align="left">Flexural modulus [MPa]</entry><entry align="center">13500</entry></row><row><entry align="left">Impact strength [kJ / m²]</entry><entry align="center">7.5</entry></row><row><entry align="left">Lin. Therm. Expansion coefficient α [K^-1]</entry><entry align="center">31.10^-6</entry></row></tbody></tgroup></table></tables>