Electrical insulation enamels composed of modified polymers and electrical conductors produced therefrom and having improved sliding capacity

Abstract

The present invention relates to electrical insulation enamels which contain a polymer comprising a base polymer and modifying units which are incompatible with the base polymer after the polymer has cured and lead to the formation of separate phases at the surface, and to processes for the production thereof. The electrical insulation enamels have a low coefficient of friction and frictional resistance and are preferably suitable for the coating of wires.

Claims

1. An electrical insulation enamel comprising a base polymer and modifying units which are incompatible with the base polymer after the polymer has cured, wherein the base polymer is polyamide-imide and the modifying units are polydialkylsiloxanes which comprise 40 to 500 Si units, further comprising combinations of the base polymer with a plurality of different modifying units having a different number of Si units and wherein the cured enamel has a phase separation on the surface with separate regions formed from the base polymer and other separate regions formed from the modifying units.

2. The electrical insulation enamel of claim 1, wherein the modifying units are polydimethylsiloxanes.

3. A cured electrical insulation enamel which can be obtained by thermally curing the electrical insulation enamel of claim 1, comprising separate regions on the surface of the cured electrical insulation enamel.

4. A process for producing the electrical insulation enamel of claim 1, comprising: polymerizing a first modified block, for example a monomer or a prepolymer, which comprises at least one modifying unit, with at least one second monomer, so as to obtain a polymer comprising modifying units; and, formulating the polymer comprising modifying units with a solvent and optionally additives so as to form an electrical insulation enamel.

5. A process for producing a coated wire, comprising: polymerizing a first modified block, for example a monomer or a prepolymer, with at least one modifying unit comprising at least a second monomer, so as to obtain a polymer comprising modifying units; formulating the polymer comprising modifying units with a solvent and optionally additives so as to form an electrical insulation enamel of claim 1; applying the electrical insulation enamel to a wire; and, subjecting the wire with the applied electrical insulation enamel to a firing process, there being separate regions on the surface of the cured electrical insulation enamel.

6. A wire coated with the electrical insulation enamel of claim 1.

7. A wire comprising electrical insulation enamel without modifying units wherein the electrical insulation enamel of claim 1 is applied, as an outer layer or layers, to the wire.

8. A wire coated with the electrical insulation enamel of claim 3.

9. A wire comprising an electrical insulation enamel without modifying units and an outer layer or layers of the electrical insulating enamel of claim 3.

10. A coil comprising the wire of claim 8.

11. An electrical insulation enamel, comprising a base polymer and polydialkylsiloxane gel particles, wherein the base polymer is polyamide-imide and the polydialkylsiloxane gel particles comprise a plurality of polydialkylsiloxanes comprising a different number of Si units and comprising 40 to 500 Si units, further comprising combinations of the base polymer with the plurality of different polydialkylsiloxanes and wherein the enamel has a phase separation on the surface with separate regions formed from the base polymer and other separate regions formed from the plurality of different polydialkylsiloxanes.

12. The electrical insulation enamel of claim 11, wherein the polydialkylsiloxane gel particles are polydimethylsiloxane gel particles.

13. A cured electrical insulation enamel which can be obtained by thermally curing the electrical insulation enamel of claim 11.

14. A process for producing the electrical insulation enamel of claim 11, comprising mixing a polysiloxane gel particle dispersion and an enamel which contains a polymer.

15. The process of claim 14, wherein the enamel which contains the polymer is a conventional enamel or an electrical insulation enamel comprising a base polymer and modifying units which are incompatible with the base polymer after the polymer has cured, wherein the base polymer is polyamide-imide and the modifying units are polydialkylsiloxanes which comprise 40 to 500 Si units, further comprising combinations of the base polymer with a plurality of different modifying units having a different number of Si units and wherein the cured enamel has a phase separation on the surface with separate regions formed from the base polymer and other separate regions formed from the modifying units.

16. A wire comprising the electrical insulation enamel of claim 11.

17. A wire coated with the electrical insulation enamel of claim 13.

18. A wire which comprises an electrical insulation enamel without modifying units and an outer layer or layers comprising the electrical insulation enamel of claim 13.

19. A coil comprising the wire of claim 17.

20. The wire of claim 9, wherein the wire is a copper wire.

21. The wire of claim 10, wherein the wire is a copper wire.

22. The wire of claim 16, wherein the wire is a copper wire.

23. The wire of claim 17, wherein the wire is a copper wire.

24. The wire of claim 18, wherein the wire is a copper wire.

25. A coil comprising the wire of claim 23.

Description

DRAWINGS

(1) The phase separation of the polymers and the modifying units is clear from FIGS. 1a and 1b.

(2) FIG. 1a is an atomic force microscopy photograph of the surface of the electrical insulation enamel according to the invention based on a polyamide-imide polydimethylsiloxane block copolymer, the polydimethylsiloxanes comprising approximately 63 Si units. The electrical insulation enamel is applied to a metal plate.

(3) A major phase separation can be seen on the surface of the electrical insulation enamel between the modifying units, which can be seen as dark bubbles, and the polymer.

(4) FIG. 1b shows an atomic force microscopy photograph of the surface of an electrical insulation enamel based on a polyamide-imide polydimethylsiloxane block copolymer, the polydimethylsiloxanes comprising approximately 10 Si units. The electrical insulation enamel is applied to a metal plate.

(5) No major phase separation can be seen between the modifying units and the polymer.

(6) The comparison between FIG. 1a, where a polydimethylsiloxane having a chain length of 63 Si units is used, and FIG. 1b, where a polydimethylsiloxane having a much shorter chain length of 10 Si units is used, clearly shows that a phase separation only occurs for a polymer having modifying units according to the present invention.

(7) FIG. 2a-g show suitable polydimethylsiloxanes for the electrical insulation enamel according to the invention.

(8) FIG. 3a-d show various embodiments of the polymers according to the invention.

(9) FIG. 4 shows a D3 atomic force microscopy photograph of the surface of a coating of a polyamide-imide which is functionally modified with a polydimethylsiloxane. The brightly displayed regions are mobile but fixed siloxane segments.

EXAMPLES

Example 1

(10) Production of a polyamide having a 20% Content of -(2,2-dimethylolbutoxy)-propyl--n-butylpolydimethylsiloxane-functionalised polymer

(11) 300.0 g N-methylpyrrolidone (NMP) and 250.0 g xyleneas a process solventand 293.5 g 4,4-diioscyanatodiphenylmethane (MDI) are weighed into a glass laboratory reactor of 2 l total volume, equipped with an electrical resistance heater having temperature monitoring and control, comprising an agitator and a reflux cooler and the introduction of protective gas (nitrogen), and the reaction mixture is gently heated. The MDI is dissolved in the previously introduced solvent at 45 C. Subsequently, 104.0 g of the -(2,2-dimethylolbutoxy)-propyl--n-butylpolydimethylsiloxane, which comprises approximately 63 Si units, are metered in over a period of 15 minutes, whilst the temperature is kept at 45 C. Subsequently, the reaction mixture is heated to 70 C., and is stirred for one hour at 70 C. Subsequently, the reaction mixture is cooled to 45 C., and 218.0 g trimellitic acid anhydride (TMA) are added. Subsequently, the mixture is stirred for one hour at 45 to 50 C. Subsequently, the temperature is increased in steps while stirring: 30 minutes at 65 C., then 30 minutes at 75 C., then 60 minutes at 85 C., then 60 minutes at 100 C., and finally 60 minutes at 130 to 140 C. In the process, the reaction product carboxylic acid dissociates from the carboxyl groups and isocyanate. The reaction mixture reaches a viscosity (measured on a sample in the cone/plate viscometer at 30 C.) of 6 Pa.Math.s. It is cooled to less than 60 C., and 6.1 g ethanol are added so as to halt the reaction. The resulting colloidal solution has a solids content of 48% (measured at 1 hour at 130 C. in the circulating furnace). The content of incompatible polydimethylsiloxane is 20% by mass, based on the polymer as a whole (solids).

Control Example (VB)

(12) Production of a polyamide-imide without Modifying Units

(13) The procedure is the same as in Example 1, but without the addition of the incompatible polydimethylsiloxane. 300.0 g NMP and 250.0 g xylene as a process solvent are weighed into the laboratory reactor described above, and 293.5 g 4,4-diioscyanatodiphenylmethane are dissolved therein at 45 C. Subsequently, 223.1 g TMA are added. Subsequently, the mixture is stirred for one hour at 45 to 50 C. Subsequently, the temperature is increased in steps while stirring: 30 minutes at 45 C., then 30 minutes at 75 C., then 60 minutes at 85 C., then 60 minutes at 100 C., and finally 60 minutes at 130 to 140 C. In the process, the reaction product carboxylic acid dissociates from the carboxyl groups and isocyanate. The reaction mixture reaches a viscosity (measured on a sample in the cone/plate viscometer at 30 C.) of 6 Pa.Math.s. It is cooled to less than 60 C. The resulting colloidal solution has a solids content of 42.9% (measured at 1 hour at 130 C. in the circulating furnace).

Example 2

(14) Production of a polyamide-imide having a 20% Content of -(2,2-dimethylolbutoxy)-propyl--n-butylpolydimethylsiloxane-functionalised polymer

(15) The procedure is the same as was described in Example 1. The amounts to be weighed in are given in Table 1.

Example 3

(16) Production of a polyamide-imide having a 5% Content of -(2,2-dimethylolbutoxy)-propyl--n-butylpolydimethylsiloxane-functionalised polymer

(17) The procedure is the same as was described in Example 1. The amounts to be weighed in are given in Table 1.

Example 4

(18) Production of a polyamide-imide having a 20% Content of aminopropyl-polydimethylsiloxane-functionalised polymer

(19) 547.6 g NMP and 228.0 g TMA are weighed into the apparatus described in Example 1. The TMA is dissolved while stirring at 70 C. Subsequently, 102.5 g of an aminopropyl polydimethylsiloxane, which comprises approximately 65 Si units, are metered in over a period of 15 minutes. The mixture is heated to 120 C., and subsequently kept at 120 C. for 1 hour so that the polydimethylsiloxane can be reacted to exhaustion. It is subsequently cooled to 40 C. and subsequently 280.0 g MDI are added over a period of one hour. It is heated to 85 C. over a period of 2 hours and subsequently to 130 C., until a viscosity of 6 Pa.Math.s is reached (measured in the plate/cone viscometer at 30 C.). Subsequently, the reaction mixture is cooled. The resulting product has a solids content of 46.9% (measured at 1 hour at 130 C. in the circulating furnace).

Example 5

(20) Production of a polyamide-imide having a 20% Content of hydroxyethoxypropyl-polydimethylsiloxane-functionalised polymer (the polydimethylsiloxane Comprises Approximately 132 Si Units)

(21) The procedure is the same as was described in Example 1. The amounts to be weighed in are given in Table 1.

(22) TABLE-US-00001 TABLE 1 Examples of polyamide-imides comprising modifying units and control example Components [g] B1 B2 B3 B4 B5 VB N-methyl- 300.0 300.0 300.0 547.6 300.0 300.0 pyrrolidone Xylene 250.0 250.0 250.0 250.0 250.0 4,4-diioscyan- 293.5 293.5 293.5 270.0 293.5 146.8 atodiphenyl methane (MDI) Trimellitic acid 218.0 218.0 218.0 228.0 224.0 111.6 anhydride (TMA) -(2,2-dimethyl- 104.0 46.0 22.0 olbutoxy)-propyl- -n-butylpoly- dimethylsiloxane Aminopropyl 102.1 polydimethyl- siloxane 2-hydroxyethoxy- 105.0 propyl polydi- methylsiloxane NMP 33.1 Ethanol 6.1 6.1 6.1 6.1 6.1 Separated CO.sub.2 101.4 102.4 102.85 93.7 102.8 103.2 Total 1070.2 1011.2 986.7 1093.6 1075.2 963.4 Solids [%] 48.6 45.6 44.3 46.9 48.3 42.9 (1 h, 130 C.) Content of 20 10 5 20 20 polymer comprising modifying units [%]

Examples 6-11

(23) Electrical Insulation Enamels

(24) Electrical insulation enamels were produced from the polymer solutions described in Examples 1-5 and the control example, by adding solvents. The composition of the electrical insulation enamels is shown in Table 2.

(25) TABLE-US-00002 TABLE 2 Electrical insulation enamels Number of Si units in the poly- dimethyl- Component siloxane [g] chain B6 B7 B8 B9 B10 B11 Polymer Ex. 1 approx. 488.8 244.4 (20% 63 modification) Polymer Ex. 2 approx. 502.8 (10% 63 modification) Polymer Ex. 3 approx. 488.8 (5% 63 modification) Polymer Ex. 4 approx. 502.8 (20% 65 modification) Polymer Ex. 5 approx. 244.4 (20% 132 modification) Polymer 502.8 control example N-methyl- 156.2 119.8 98.5 617.5 118.4 82.9 pyrrolidone N,N- 32.3 31.2 29.4 56.1 30.4 29.3 dimethyl- acetamide Total 677.4 653.8 616.7 1176.4 637.6 615.0 Solids [%] (60 35.1 35.1 35.1 20.0 35.1 35.1 min., 130 C.) Viscosity 710 860 780 350 660 830 [mPa .Math. s] (plate/cone viscosity)
Applications of the Electrical Insulation Enamels

(26) The electrical insulation enamels shown in Table 2 were enamelled on a horizontally operating wire enameling machine at an ambient temperature of at most 605 C. The blank wire diameter was 0.53 mm, and the haul-off speed was 122 m/min. The application was carried out by way of immersions using nozzle strippers. There was a total of 10 passes. The application for the first 7 passes consisted of a conventional commercial polyester-imide electrical insulation enamel, using a nozzle sequence of 560/570/570/580/580/590/590 m. The following 2 applications consisted of a conventional commercial polyamide-imide electrical insulation enamel, using a nozzle sequence of 590/600 m. The final application consisted of the insulation enamel according to the invention in accordance with Examples 6-10 or the enamel from the control example in accordance with Example 11, using a nozzle having a 610 m opening diameter.

(27) Testing the Sliding Capacity

(28) As well as testing the thermal resistance and electrical properties, the sliding capacity was determined by two methods.

(29) 1. Measuring the Surface Resistance in Accordance with Parusel Coefficient of Friction

(30) When the surface resistance is measured in accordance with the Parusel coefficient of friction, an enamelled wire is passed between a polished steel surface and a steel slide lying thereon. The force which acts on the steel slide is measured. This results in a (dimensionless) coefficient of friction. Low values of the coefficient of friction mean low friction (tensiometry, see DIN EN 60851).

(31) 2. Measuring the Frictional Resistance in Accordance with Scintilla

(32) An enamelled wire is passed at high speed under a steel block having a particular contact surface area. The force which is produced by the friction is measured. The result is in newtons (N).

(33) Table 3 shows the measurement results for the enamelled wires and for the enamelled wire using the control example.

(34) TABLE-US-00003 TABLE 3 Measurement results for frictional resistance Measurement method/ example B6 B7 B8 B9 B10 B11 Number of Si units appr. 63 appr. 63 appr. 63 appr. 65 appr. 132 Parusel CoF (DIN EN 60851) 0.120 0.130 0.210 0.132 0.099 0.230 Scintilla [N] 5.50 6.50 7.00 5.50 5.50 14.00

(35) The measurement results shown in Table 3 demonstrate the advantage of the electrical insulation enamel according to the invention (B6-10) over an electrical insulation enamel without modifying units (B11). The higher the content of the modifying units in the polymer (cf. B6 20%, B7 10%, B8 5%), the lower the coefficient of friction and the frictional resistance are. A particularly low coefficient of friction is achieved by mixing two polymers, comprising modifying units which comprise a different number of Si units, in a mass ratio of 50:50 (see B 10).

Example 12

(36) Production of a polyester-imide Modified with polydimethylsiloxane (PDMS)

(37) A laboratory reactor (V4A, glass) having indirect heating (for example heat transfer oil) or controllable electrical resistance heating, product temperature monitoring, protective gas introduction, a continuously controllable maximally edge-to-edge agitator, a filling body column with head temperature measurement, bridge and descending reflux cooler (all distillate collected) is used as the reaction vessel. The column is moved as a dephlegmator.

(38) The total amount of polyols (THEIC or glycerol, ethylene glycol), dimethyl terephthalate and 0.3% (based on the yield amount of the polyester-imide as a whole=nfA) butyltitanate are weighed in the stated sequence (see also recipe in Table 4). Subsequently, entrainer is added: Solvesso 150 as approximately 3% of total amount weighed in.

(39) Starting to introduce the protective gas (most preferably nitrogen, but carbon dioxide or a mixture thereof with N.sub.2 can also be used).

(40) The reaction mixture is rapidly heated to approximately 160 C. Subsequently, the temperature is increased to max. 240 C. continuously over 5 hours. The time measurement is determined by the distillation process; the column head temperature should not exceed 75 C. (somewhat above the boiling point of methanol, 64.7 C.). The methanol which has distilled off is collected and the amount thereof is determined (density at 20 C.=0.7869). The reaction mixture is kept at 240 C., until no more methanol accumulates. Subsequently, the mixture is cooled to less than 140 C.

(41) Subsequently, amine-functional polydimethylsiloxane is added. Trimellitic acid anhydride and 4,4-diaminophenyl methane is added as a solid mixture, but at least in alternating portions. Subsequently, the mixture is heated again cautiously. The diimide carboxylic acid forms spontaneously and precipitates out. Enough Solvesso 150 is added to make the dispersion easy to stir.

(42) Subsequently, the mixture is initially heated slowly to up to 240 C. The time measurement is determined by the distillation process; the column should not flood and the column head temperature should not exceed 105 C. (somewhat above the boiling point of water).

(43) From 200 C. upwards, samples for measuring the acid number and viscosity are obtained. The acid number is determined by titration using 0.5 molar alcoholic KOH against phenolphthalein on a sample dissolved in preneutralised solvent [DIN 53169]. The dynamic viscosity is determined using a sample nfA 60% in solvent.

(44) The reaction mixture is kept at 220 C. until the acid number is below 20 mg KOH/g.

(45) Subsequently, the laboratory reactor is switched to the short path (descending distillation bridge, best for determining the distillation temperature) and the entrainer and residual water are distilled off. The mixture is kept at 220 C. until the intended characteristic values are reached.

(46) Subsequently, the mixture is cooled to well below 170 C., and partially dissolved, by adding approximately 5-10% of the intended amount of solvent, before cooling again. At less than 130 C., the content of the laboratory reactor is discharged and further dissolved in the main amount of the solvent.

(47) TABLE-US-00004 Final characteristic nfA (60 min., 130 C.): 70.0 1.0% values to be set: Acid No. (solid): 5-15 mg KOH/g Viscosity (dyn.): 50 mPa .Math. s (original partial dissolution, 23 C.)

(48) TABLE-US-00005 TABLE 4 Recipe: Components [g] Weigh in [g] Dimethylterephthalate 64.02 Trimellitic acid anhydride 84.48 N,N-diaminodiphenylmethane 43.56 Trishydroxyethyl isocyanate 96.18 Glycerol 0.00 Ethylene glycol 21.48 Modifier: amine-functional PDMS, for example: Aldrich: 30.86 480304 Poly[dimethylsiloxane-co-(3-aminopropyl)methylsiloxane] Catalysts and solvents: Butyltitanate 0.99 Solvanol PCA (or cresols/phenols) or xylene 9.90 Solvesso 150 9.90 Total, weighed in polymer blocks 340.58 Total methanol release 7.69 Total H.sub.2O release 2.33 Modification content [%] 10%

Example 13

(49) Production of a polyamide-imide Comprising a 5% Content of aminopropylmethylsiloxane dimethylsiloxane Copolymer Modifier

(50) PDMS Modifier

(51) TABLE-US-00006 Molecular Mole % Code weight (aminopropyl) (ABCR) Viscosity [g/mol] MeSiO AMS-132 80-100 4500-5500 2.0-3.0 AMS-152 120-180 7000-8000 4.0-5.0 AMS-162 80-120 4000-5000 6.0-7.0 AMS-132: (2-3% aminopropylmethylsiloxane) dimethylsiloxane copolymer AMS-152: (4-5% aminopropylmethylsiloxane) dimethylsiloxane copolymer AMS-162: (6-7% aminopropylmethylsiloxane) dimethylsiloxane copolymer

(52) 100 g NMP, 50 g xylene and 45.6 g trimellitic acid anhydride (TMA) are weighed into a glass laboratory reactor having 0.5 l total volume, equipped with electrical resistance heating with temperature monitoring and control, with an agitator and a reflux cooler and the introduction of nitrogen. The TMA is dissolved at 70 C. while stirring. Subsequently, 4.6 g of the PDMS modifier, which comprises approximately 70-100 Si units, are metered in over a period of 15 min. The mixture is heated to 120 C., and subsequently kept at 120 C. for one hour so as to react the PDMS component to exhaustion. It is subsequently cooled to 40 C., and subsequently 58.7 g MDI are added over a period of one hour. The mixture is heated to 85 C. over a period of two hours, and subsequently to 130 C. until a viscosity of 5 Pa.Math.s (measured in the plate/cone viscometer at 30 C.) is achieved. Subsequently, the mixture is cooled to 70 C., and by adding 1.2 g ethanol, the remaining free isocyanate functions are reacted. The resulting product has a solids content of 47-51% (measured at 1 hour, 130 C. in the circulating furnace): AMS-123: 51% solids; AMS-152: 47% solids; AMS-162: 48% solids.

(53) Application and Firing Conditions

(54) The PAI which had been functionalised with AMS-132 was set to a solids content of 40% by adding NMP, and 200 m thereof were applied and fired for 10 min at 220 C.

(55) The coated sheet metal was tested on the IFAM.

Example 14

(56) Production of the Aqueous Polyurethane Dispersions Comprising a 5% Content of (2-3% aminopropylmethylsiloxane) dimethylsiloxane Copolymer as a Modifier

(57) 14.1

(58) 36.15 g MDI are dissolved in 74 g butanone at 82 C. in a reaction apparatus as described in Example 13. Subsequently, 41.27 g Priplast 1838, 1.43 g neopentylglycol (NPG), 6.46 g dimethanolpropionic acid (DMPA) and 7.93 g cyclohexyldimethanol (CHDM) are added in succession, and this reaction mixture is brought to reaction at 82 C. for 3 hours. After cooling to room temperature, 4.66 g of the modifier AMS-132 is added in drops over 15 min. After a further 15 min of stirring at 50 C., 1.77 g butanol are added and the mixture is kept at 82 C. for 30 min. After adding 2.14 g dimethylethylethanolamine (DMEA) over a period of 5 min, the mixture is stirred for a further 30 min at 82 C. After cooling to 65 C., 9.64 g butylglycol are added and the mixture is stirred for 30 min. Subsequently, 138.6 g water are added. Subsequently, the butanone is distilled off from the resulting dispersion on the rotary evaporator.

(59) The resulting product is set to a solids content of 40% (measured at 1 hour, 130 C. in the circulating furnace) by adding water.

(60) The polyurethane dispersion is set to a solids content of 25%, a 200 m wet film thickness is applied using a doctor blade, and it is fired at 100 C. for 10 min.

(61) TABLE-US-00007 Polyurethane 6 (solids = 40%) Chemicals n M [g/mol] Butanone 72.11 MDI 1.05 250.25 Priplast 1838 0.15 NPG 0.1 104.16 DMPA 0.35 134.16 CHDM 0.4 144.2 Modifier 5000 Butanol 0.174 74.12 DMEA 0.175 89.14 Butylglycol 0.593 118.18 Bidest
14.2

(62) 52.55 g MDI are dissolved in 85.9 g butanone at 82 C. in a reaction apparatus as described in Example 13. Subsequently, 40 g Priplast 1838, 2.08 g neopentylglycol (NPG), 9.38 g dimethanolpropionic acid (DMPA) and 12.96 g cyclohexyldimethanol (CHDM) are added in succession, and this reaction mixture is brought to reaction at 82 C. for 3 hours. After cooling to room temperature, 6.13 g of the modifier AMS-132 is added in drops over 15 min. After a further 15 min of stirring at 50 C., 2.58 g butanol are added and the mixture is kept at 82 C. for 30 min. After adding 3.12 g dimethylethylethanolamine (DMEA) over a period of 5 min, the mixture is stirred for a further 30 min at 82 C. After cooling to 65 C., 14 g butylglycol are added and the mixture is stirred for 30 min. Subsequently, 176.6 g water are added. Subsequently, the butanone is distilled off from the resulting dispersion on the rotary evaporator.

(63) The resulting product is set to a solids content of 40% (measured at 1 hour, 130 C. in the circulating furnace) by adding water.

(64) The polyurethane dispersion is set to a solids content of 30%, a 200 m wet film thickness is applied using a doctor blade, and it is fired at 100 C. for 10 min.

(65) TABLE-US-00008 Polyurethane 9 (solids = 40%) Chemicals n M [g/mol] Butanone 72.11 MDI 1.05 250.25 Priplast 1838 0.1 NPG 0.1 104.16 DMPA 0.35 134.16 CHDM 0.45 144.2 Modifier 5000 Butanol 0.174 74.12 DMEA 0.175 89.14 Butylglycol 0.593 118.18 Bidest
14.3

(66) 52.55 g MDI are dissolved in 90 g butanone at 82 C. in a reaction apparatus as described in Example 1. Subsequently, 30 g Priplast 1838, 2.08 g neopentylglycol (NPG), 9.38 g dimethanolpropionic acid (DMPA) and 13.68 g cyclohexyldimethanol (CHDM) are added in succession, and this reaction mixture is brought to reaction at 82 C. for 3 hours. After cooling to room temperature, 5.66 g of the modifier AMS-132 is added in drops over 15 min. After a further 15 min of stirring at 50 C., 2.58 g butanol are added and the mixture is kept at 82 C. for 30 min. After adding 3.12 g dimethylethylethanolamine (DMEA) over a period of 5 min, the mixture is stirred for a further 30 min at 82 C. After cooling to 65 C., 14 g butylglycol are added and the mixture is stirred for 30 min. Subsequently, 164.4 g water are added. Subsequently, the butanone is distilled off from the resulting dispersion on the rotary evaporator.

(67) The resulting product is set to a solids content of 40% (measured at 1 hour, 130 C. in the circulating furnace) by adding water.

(68) The polyurethane dispersion is set to a solids content of 30%, a 200 m wet film thickness is applied using a doctor blade, and it is fired at 100 C. for 10 min.

(69) TABLE-US-00009 Polyurethane 10 (solids = 40%) Chemicals n M [g/mol] Butanone 72.11 MDI 1.05 250.25 Priplast 1838 0.075 NPG 0.1 104.16 DMPA 0.35 134.16 CHDM 0.475 144.2 Modifier 5000 Butanol 0.174 74.12 DMEA 0.175 89.14 Butylglycol 0.593 118.18 Bidest

Example 15

(70) Synthesis Procedure for In Situ Synthesis of a PDMS Gel Particle Dispersion

(71) The disperse phase (NMP position 1) and a suitable emulsifying agent (position 2) are placed in advance in a 2 liter glass reactor having a maximally wall-to-wall anchor agitator and a reflux cooler.

(72) The vinyl-functional PDMS prepolymer (position 3) is mixed with a suitable catalyst (position 4) filled into a dropping funnel.

(73) The hydride-functionalised PDMS prepolymer (position 5) is filled into a further dropping funnel.

(74) The two prepolymers are added in drops over a period of approximately 10 min with intensive stirring.

(75) (By way of the catalyst selection, the necessary reaction temperature can be varied from room temperature to over 100 C.)

(76) The mixture is stirred intensively for a further 5 hours and subsequently stirred slowly for 20 hours.

(77) Example recipe GP2002:

(78) TABLE-US-00010 Raw Chem. Molar Function- Equivalent Masses Pos. material name mass ality [%] [%] 1 Disperse N-methyl- 79.496 phase pyrrolidone 2 Emulsi- Silicon 0.3 fying glycol agent D.C. copolymer Fluid 190 3 ABCR: Divinyl- 800 2 47.3 5.6 DMS V05 terminated poly- dimethyl- siloxane (prepolymer) 4 ABCR: Pt Catalyst 0.204 SIP (active at 6830.3 room temp.) 5 ABC: Methyl- 6000 6.49 52.7 14.4 HMS-082 hydro- siloxane dimethyl- siloxane copolymer (prepolymer) TOTAL: 100.00 100.00

(79) The dispersion obtained of crosslinked PDMS gel particles is worked into conventional NMP-based polyamide-imide electrical insulation enamel (for example using Dispermats or Ultra-Turraxes).

(80) Content of the dispersion in the blend:

(81) 1-75 (PDMS gel particle dispersion); preferably 5-20%; particularly preferably approx. 10%

(82) Advantages of this synthesis and of the PDMS gel particles obtained:

(83) The mesh width of the crosslinked gel particles can be controlled by way of the functionality and molar mass of the prepolymers.

(84) As a result of using monovinyl-functional prepolymers, dangling ends (free polymer ends) can be introduced, and gel particles having a PDMS brush surface can be produced.

(85) As a result of using an excess of divinyl-functional prepolymers, dangling ends (free polymer ends) can similarly be introduced, and gel particles having a PDMS brush surface can be produced.

(86) As a result of the crosslinking within the gel particles, the migration capacity of the siloxanes is suppressed.

(87) As a result of the in situ synthesis in NMP, the dispersion obtained can be worked directly into an NMP-based electrical insulation enamel.

(88) The dispersion obtained of crosslinked PDMS gel particles can be worked into an NMP-based electrical insulation enamel as an additive; as a result of missing polyether segments, the thermal stability is increased by comparison with conventional lubricant additives (polyether polydimethylsiloxane copolymers)

Example 16

(89) Application Tests Using PDMS Gel Particle Dispersions

(90) Table 5 shows mixtures of electrical insulation enamels and PDMS gel particles for which application tests are carried out with subsequent friction tests.

(91) The PDMS gel particle dispersions were worked into a conventional NMP-based polyamide-imide electrical insulation enamel and into a modified enamel consisting of polyamide-imide polydimethylsiloxane block copolymers having a 20% PDMS content.

(92) TABLE-US-00011 TABLE 5 Content of modified poly- Content Content Content Content amide- of of of of non- imide Friction PDMS PDMS PDMS modified enamel test, gel gel gel poly- PAI LM Parusel particle particle particle amide- 28C30C CoF Friction disper- disper- disper- imide (20% (DIN test, sion sion sion enamel PDMS EN Scintilla GP 2001 GP 2002 GP 2007 595/30 content) 60851) [N] 10% 90% 0.115 5.5 40% 60% 0.180 7.75 75% 25% 0.195 8.0 40% 60% 0.174 8.5 100% 0.241 7.25 10% 90% 0.127 5.5 40% 60% 0.139 7.5 75% 25% 0.141 7.0 Control: pure PAI 100% 0.230 14.0
Sliding Capacity Test

(93) As well as testing the thermal resistance and electrical properties, the sliding capacity was determined by two methods.

(94) 1. Measuring the Surface Resistance in Accordance with Parusel Coefficient of Friction

(95) When the surface resistance is measured in accordance with the Parusel coefficient of friction, an enamelled wire is passed between a polished steel surface and a steel slide lying thereon. The force which acts on the steel slide is measured. This results in a (dimensionless) coefficient of friction. Low values of the coefficient of friction mean low friction (tensiometry, see DIN EN 60851).

(96) 2. Measuring the Frictional Resistance in Accordance with Scintilla

(97) An enamelled wire is passed at high speed under a steel block having a particular contact surface area. The force which is produced by the friction is measured. The result is in newtons (N).