Tape Comprising A Hybrid Binder For High Voltage Application

Abstract

The present invention relates to a tape comprising an epoxy based resin having ester groups and ethylenically unsaturated groups, alternatively a hybrid resin. The tape of the invention can be used for insulation in electrical machines, especially in high voltage machines. Preferably, the tape of the invention is used in combination with a composition for impregnating and/or coating a substrate comprising the tape of the invention, wherein the composition further comprises a second epoxy based resin having ester groups and ethylenically unsaturated groups, also an hybrid resin, a diluent and an initiator for a radical polymerization.

Claims

1. A tape comprising mica, a solid support and a resin component Z, the resin component Z comprising: i. one or more, the same or different, groups of formula ##STR00010## wherein R is an organic group comprising 2 to 40 carbon atoms; and ii. one or more groups comprising one ester group and one ethylenically unsaturated group; wherein the resin component Z has an acid value of not more than 60 mgKOH/g.

2. The tape of claim 1, wherein the resin component Z further comprises: iii. one or more groups comprising two ester groups and one ethylenically unsaturated group.

3. The tape of claim 1, wherein the resin component Z consists essentially of: i. one or more, the same or different, groups of formula ##STR00011## wherein R is an organic group comprising 2 to 40 carbon atoms; ii. one or more groups comprising one ester group and one ethylenically unsaturated group; and optionally iii. one or more groups comprising two ester groups and one ethylenically unsaturated group.

4. The tape of claim 1, wherein R comprises a hydrocarbon part of a bisphenol A unit or a bisphenol F unit.

5. The tape of claim 1, wherein the one or more groups ii. comprising one ester group and one ethylenically unsaturated group comprises one or more of an acrylic ester and a methacrylic.

6. The tape of claim 2, wherein the one or more groups iii. comprising two ester groups and one ethylenically unsaturated group comprises an ester group of one or more of fumaric acid, maleic acid, maleic anhydride, itaconic acid, and citraconic acid.

7. The tape of claim 1, wherein the resin component Z is obtained as a reaction product of an epoxy resin and a compound comprising one carboxylic acid group and one ethylenically unsaturated group.

8. The tape of claim 7, wherein the resin component Z is obtained as a reaction product of an epoxy resin, a compound comprising one carboxylic acid group and one ethylenically unsaturated group, and a compound comprising a) two carboxylic acid groups or a carboxylic acid anhydride group, and b) one ethylenically unsaturated group.

9. The tape of claim 7, wherein the epoxy resin further comprises one or more of bisphenol A and bisphenol F.

10. A process for preparing a tape, the process comprising: providing a material comprising mica, a solid support and a resin component Z, the resin component Z comprising: i. one or more, the same or different, groups of formula ##STR00012## wherein R is an organic group comprising 2 to 40 carbon atoms; and ii. one or more groups comprising one ester group and one ethylenically unsaturated group; and bonding the material comprising mica and the solid support with the resin component Z, wherein the resin component Z has an acid value of not more than 60 mgKOH/g.

11. A tape comprising a resin component Z, the resin component Z comprising: i. one or more, the same or different, groups of formula ##STR00013## wherein R is an organic group comprising 2 to 40 carbon atoms; and ii. one or more groups comprising one ester group and one ethylenically unsaturated group, wherein the resin component Z has an acid value of not more than 60 mgKOH/g.

12. A substrate comprising a metal and the tape of claim 1.

13. (canceled)

14. A process for preparing a treated substrate, the process comprising: wrapping a substrate comprising a metal with a tape to obtain a wrapped substrate, the tape comprising mica and a solid support; one or more of coating and impregnating the wrapped substrate with a composition, the composition comprising: A) a resin component comprising: one or more, the same or different, groups of formula ##STR00014## wherein R is an organic group comprising 2 to 40 carbon atoms; ii. one or more groups comprising two ester groups and one ethylenically unsaturated group; and iii. one or more terminal or pendant groups comprising one ester group and one ethylenically unsaturated group; B) at least one reactive diluent comprising at least one ethylenically unsaturated polymerizable group and having a boiling point at atmospheric pressure higher than 200° C.; and C) an initiator for radical polymerization; and curing the wrapped and one or more of impregnated and coated substrate.

15. A treated substrate obtained by the process of claim 14.

16. A tape prepared from a composition comprising: A) a resin component comprising: i. one or more, the same or different, groups of formula ##STR00015## wherein R is an organic group comprising 2 to 40 carbon atoms; ii. one or more groups comprising two ester groups and one ethylenically unsaturated group; and iii. one or more terminal or pendant groups comprising one ester group and one ethylenically unsaturated group; B) at least one reactive diluent having at least one ethylenically unsaturated polymerizable group and having a boiling point at atmospheric pressure higher than 200° C.; and C) an initiator for radical polymerization.

17. An electric machine comprising an electrical conductor and electrical insulation, the electrical insulation comprising the tape of claim 16.

18. A substrate comprising a metal and the tape of claim 2.

19. The process of claim 10, wherein the resin component Z further comprises: iii. one or more groups comprising two ester groups and one ethylenically unsaturated group.

20. The process of claim 19, wherein the resin component Z is obtained as a reaction product of an epoxy resin, a compound comprising one carboxylic acid group and one ethylenically unsaturated group, and a compound comprising a) two carboxylic acid groups or a carboxylic acid anhydride group, and b) one ethylenically unsaturated group.

21. The tape of claim 11, wherein the resin component Z further comprises: iii. one or more groups comprising two ester groups and one ethylenically unsaturated group.

22. The tape of claim 21, wherein the resin component Z is obtained as a reaction product of an epoxy resin, a compound comprising one carboxylic acid group and one ethylenically unsaturated group, and a compound comprising a) two carboxylic acid groups or a carboxylic acid anhydride group, and b) one ethylenically unsaturated group.

Description

EXAMPLES

Examples Al to Al 1

[0153] 1. Preparation of the composition comprising resin component A.

[0154] The resins were synthesized using a glass reactor equipped with a water-cooled condenser. A combination of nitrogen and air was bubbled into the reactor. Bisphenol F and/or Bisphenol A type epoxy resin (EPON 824, 344 grams) and inhibitors were added to the reactor and agitation was turned on. Glacial acrylic or methacrylic acid (140 grams) and Ancamine K54 (0.6 grams) catalyst were then added into the vessel, and the reaction mixture was heated to 99° C. An exotherm was observed that increased the temperature of the reaction to around 121° C. The solution was then held at 104-110° C. until the acid value decreased to less than 20 mg of KOH per gram of the reaction product. The material was then cooled to less than 82° C., and maleic anhydride (22 grams) was added. The reaction temperature was then increased to 104.4-110° C. until an acid value of less than 20 mg of KOH per gram of reaction product was achieved. The reaction was then separated into multiple samples, which were allowed to cool to room temperature. The reaction product was then re-melted, additional inhibitors added, and thinned with an diallyl fumarate (DAF, 415 grams), tetraethylene glycol di-(meth)acrylate (TEGDMA, 507 grams), hexanediol di(meth)acrylate (HDDMA, 507 grams), or butanediol dimethacrylate (BDDMA, 507 grams) monomer until a viscosity of around 400 cP or less was obtained. The material was then cooled to below 49° C. and dicumyl peroxide (5-20 grams) was added. Finally, the material was filtered through a 25-micron cloth. The chemical composition is detailed in Table 1 for examples A1-A11.

TABLE-US-00001 TABLE 1 Reactive Dicumyl EX Resin Component A Diluent peroxide A1 Bis F Epoxy with Methacrylic Acid and 40% DAF 0.50% Maleic Anhydride A2 Bis F Epoxy with Methacrylic Acid and 50% 0.50% Maleic Anhydride TEGDMA A3 Bis F Epoxy with Methacrylic Acid and 50% 0.50% Maleic Anhydride HDDMA A4 Bis F Epoxy with Methacrylic Acid and 50% 0.50% Maleic Anhydride BDDMA A5 Bis F Epoxy with Methacrylic Acid and 50% 1.00% Maleic Anhydride BDDMA A6 Bis F Epoxy with Methacrylic Acid and 50% 2.00% Maleic Anhydride BDDMA A7 Bis F Epoxy with Acrylic Acid and 45% DAF 0.50% Maleic Anhydride A8 Bis F Epoxy with Acrylic Acid and 50% 0.50% Maleic Anhydride TEGDMA A9 Bis F Epoxy with Acrylic Acid and 50% 0.50% Maleic Anhydride HDDMA A10 Bis F Epoxy with Acrylic Acid and 50% 0.50% Maleic Anhydride BDDMA A11 Bis A Epoxy with Methacrylic Acid and 50% 0.50% Maleic Anhydride BDDMA

EXAMPLES

[0155] Synthesis of the Resin Component Z

[0156] The resins were synthesized using a glass reactor equipped with a water-cooled condenser.

[0157] Resin Z1: A combination of nitrogen and air was bubbled into the reactor.

[0158] Bisphenol A epoxy resin (579 grams) and inhibitors were added to the reactor and agitation was turned on. Glacial methacrylic acid (203 grams) and Ancamine K54 (0.9 grams) catalyst were then added into the vessel, and the reaction mixture was heated to 99° C. An exotherm was observed that increased the temperature of the reaction to around 121° C. The solution was then held at 104-110° C. until the acid value decreased to less than 20 mg of KOH per gram of the reaction product. The material was then cooled to less than 82° C., and maleic anhydride (32 grams) was added. The reaction temperature was then increased to 104.4-110° C. until an acid value of less than 20 mg of KOH per gram of reaction product was achieved. The reaction was then diluted with methylethyl ketone (204 grams). Finally, the material was filtered through a 25-micron cloth.

[0159] Resin Z2:

[0160] A combination of nitrogen and air was bubbled into the reactor. Styrene (37 grams) was loaded into the reactor. Bisphenol A epoxy resin (Epon 1001, 55.55 grams) and inhibitors were added to the reactor and agitation was turned on. The mixture was heated to 60° C. and held until the epoxy had dissolved. The mixture was cooled to room temperature.

[0161] Glacial methacrylic acid (4.45 grams) and Ancamine K54 (0.06grams) catalyst were then added into the vessel, and the reaction mixture was heated to 101° C. over the course of 3.5 hours at which point the acid value was 0.6-1. An unknown amount of styrene was lost through the condenser.

[0162] When cooled, the material was solid.

[0163] GPC results: Mn 1701 g/mol; Mw 4132 g/mol; Mz 7671 g/mol; PD 2.42

[0164] Resin Z3:

[0165] A combination of nitrogen and air was bubbled into the reactor. Xylene (40 grams) was loaded into the reactor and agitation was turned on. Bisphenol A epoxy resin (Epon 1001, 55.55 grams) and inhibitors were added to the reactor. The mixture was heated to 66° C. and held until the epoxy was dissolved, about 4 hours. The mixture was cooled to room temperature.

[0166] Glacial methacrylic acid (4.45 grams) was added and the mixture was heated to 109° C. and held 7 hours. The acid value was 59 mgKOH/g. The mixture was cooled to room temperature.

[0167] Glacial methacrylic acid (4.45 grams) and benzyltriethylammonium chloride (0.3 grams) were added and the mixture was set for 104° C., but exothermed to 134° C. Heat was stopped, the mixture was poured off and cooled.

[0168] GPC results: Mn 1997 g/mol; Mw 4154 g/mol; Mz 12022 g/mol; PD 2.08

[0169] Resin Z4:

[0170] A combination of nitrogen and air was bubbled into the reactor. Xylene (957.3 grams) was loaded into the reactor and agitation was turned on. Bisphenol A epoxy resin (Epon 1009, 718 grams) was added and the mixture was heated to 135° C. After one hour the epoxy was largely dispersed, but not fully dissolved. Methylisobutylketone (231 grams) was added to improve solubility. Bisphenol A epoxy resin (Epon 1009, 718 grams) was added slowly and the mixture was held at 135° C. until dissolved. Inhibitors were added and the mixture was cooled to 104° C.

[0171] Glacial methacrylic acid (40.49 grams) and benzyltriethylammonium chloride (7.38 grams) were added

[0172] And the mixture was held at 104° C. for about 4 hours until acid value was 6.7. Mixture was vacuumed and poured out of reactor to cool.

[0173] Tg by DSC: 82° C.

[0174] GPC results: Mn 4784 g/mol; Mw 15679 g/mol; Mz 40345 g/mol; PD 3.3

[0175] A sample of this material was crushed to powder and mixed with 1% dicumyl peroxide. It was evaluated by DSC. Cure onset 126° C. Peak max 169° C.

[0176] Joules/gram 32 Tg 70° C.

[0177] The material was ground with mortar & pestle and with an industrial blender. The powder was classified with sieves to produce a kilogram of powder that was Dv10 38.2 μ Dv50 134 μ Dv90 372 μ.

[0178] The powder was vacuumed for 6 hours to remove any residual solvent.

[0179] Measurements

[0180] GPC measurements were performed using Agilent Infinity 1260 GPC. The Infinity GPC is equipped with an Infinity 1260 Degasser. The Infinity GPC is equipped with an isocratic pump that is also model number Inifinity 1260. The serial number is DEAB902598. Next the Infinity GPC contains attachments for thermostating the GPC columns and autosampler features. The solvent is tetrahydrofuran (THF) and supplied by Honeywell. The purity is 99.9% with a peroxide level of less than 2 mg/L. Samples to be analyzed are first dissolved in THF with mild agitation. The samples is swirled clockwise for 39 revolutions. The sample is then placed on hot plate at 40° C. for 20 seconds. The sample is next swirled and additional 40 revolutions. Sample is analyzed for complete dissolution visually by chemist with suitable vision of 20/40 or better. If sample is not sufficiently dissolved, the sequence above is repeated until dissolution is complete. The sample is then filtered through a 5 mL syringe with a 0.5 micron filter filter housing. The solution is collected with a 5 mL vial suitable for the autosampler. A lid with a rubber septum is then crimped onto the vial using an Agilent supplied vial crimper. After all the samples have been loaded into the autosampler, the method is started. The method is set to a flow rate of 1 mL/min of THF through a mixed D column (2 in seriers) supplied by Phenomenex. The mixed D columns are thermostated at 40° C. and the refractive index detector is baseline zeroed. The effluent is collected in a suitable container with proper venting. Samples are injected on the column per the method with an injection volumn of 0.5 microliters per injection. The refractive index detector is thermostated at 40° C. also to prevent signal drift. The signal polarity is positive. The maximum pressure allowed on the column set is 600 bar. Analysis was performed with Agilent Chemstation software. Reference samples of polystyrene purchased from Agilent are run in a similar fashion to develop a calibration curve. The standards range in molecular weight of 500 to 30,000 daltons [g/mol]. The calibration curve can be a linear fit or first order or second order depending on the column set utilized. In this experiment we used a first order fit.

[0181] Acid Number

[0182] The acid number is the KOH quantity in mg that is required for neutralizing 1 g of substance under the defined conditions. The acid numbers were determined by a neutralization reaction with a 0.1 N KOH in Ethanol according to DIN EN ISO 2114.

[0183] General Procedure for the Preparation of the Samples

[0184] Mica glass fiber tapes, comprising the resin Z or a standard resin were wrapped on hollow steel bar, applying 8 half-lapped layers with 6 kg of tension; ends were sealed with a sealing product.

[0185] Then, a conductive tape was applied on external surface, to be used for dissipation factor measurement.

[0186] Bars were then closed with aluminum strips and thermal shrink tape as moulds.

[0187] These bars were impregnated using the composition of the invention comprising resin A or a standard impregnation resin with following Vacuum Process Impregnation (VPI) process: [0188] Dry vacuum phase: 16 hours at 0.5 mbar and 50° C. [0189] Impregnation resin degassed at 0.5 mbar and 45° C. [0190] Impregnation resin flooding at 0.5 mbar and 50° C. [0191] Wet vacuum phase: 1 hour at 0.5 mbar and 50° C. [0192] Pressure stage: 6 hours at 6 bar abs. and 50° C.

[0193] Bars were then cured with following curing cycle: [0194] Oven preheated at 140° C. [0195] 1 hour at 140° C. [0196] From 140° C. to 160° C. in 2 hours [0197] 12 hours at 160° C.

[0198] After curing, moulds were removed and dissipation factor of these bars was measured applying voltage from 1 kV to 12 kV, 1 kV step. All bars had flat dissipation factor profile.

[0199] Bars were then tested in two different ways: [0200] Fast ageing cycles: thermal ageing for 16 hours at increasing temperature, starting from 170° C. and increasing 10° C. each step; dissipation factor, measured after each step, stayed flat up to 220° C. cycle [0201] Long term aging: thermal ageing at 180° C. and 190° C., checking dissipation factor every 5 days; DF stayed flat for more than 100 days for both temperatures

[0202] Long-Term Aging Test

Comparative Example 1

[0203] The long-term aging tests were run for bars prepared according to the general procedure described above using an epoxy anhydride resin Epoxylite® 006-0611 as impregnation resin and a standard tape K3032 produced by Krempel which contains an epoxy based resin binder, as mica glass fiber tape.

Example 1

[0204] The long-term aging tests were run for bars impregnated with the composition of Example A11 and using a tape comprising the resin component Z of Example Z1.

[0205] Results of the Long-Term Aging Test

[0206] The bars of the Example 1 showed a constant dissipation factor for at least 130 days when aged at 190° C. In fact, the dissipation factor remains between 0.7 and 1 when the bars are aged at 190° C. for 130 days.

[0207] The bars of the Comparative Example show an increase of the dissipation factor from 0.7 to 1.2 after 15 days and to 1.7 after 20 days when measured in the same conditions of the Example 1.

[0208] The increase of the dissipation factor of the bars of the Comparative Example indicates a delamination of the insulation layer, which is no longer present in the bars of the Example of the Invention.

[0209] Fast Aging Cycle

Comparative Example 2

[0210] The fast aging cycle tests were run for bars prepared according to the general procedure described above using an epoxy resin Epoxylite® 006-0841 as impregnation resin and a standard tape K3015 produced by Krempel which contains an epoxy based resin binder, as mica glass fiber tape.

Example 2

[0211] The fast aging cycle tests were run for bars prepared according to the general procedure described above using the composition of Example A11 for impregnating the bars and using a tape comprising the resin component Z of Example Z1.

[0212] Results of the Fast Aging Cycles

[0213] The bars of the Comparative Example show an increase of the dissipation factor from 0.7 to 1.2 after the cycle at 210° C. and to 1.7 after 220° C.

[0214] The bars of the Example 2 show an increase of the dissipation factor to 2 after the cycle at 220° C.