Corona Protection Tape for Electrical High-Voltage Machine

1 . A corona shielding tape for further processing to form wound insulation by means of VPI impregnation with an anhydride-free, impregnating resin, the shielding tape comprising:

a carrier tape comprised of

a polymeric matrix having an electrically conductive and/or semiconductive filler embedded therein, and

at least one tape accelerator incorporated into the impregnating resin,

wherein in that the polymeric matrix comprises at least one polyvinyl alcohol and the tape accelerator is selected from the group consisting of the compounds I to IV and VI, where R 2 on IV is identical or nonidentical and R 2 ═H, V:

(I) is an adduct of TMPTA and one or more 1H-imidazole derivatives, R is identical or nonidentical and is selected from the group consisting of

H, methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, tert-butyl, phenyl and/or mono-, di-, tri-, tetra-, pentasubstituted phenyl,

where the substituents on the phenyl radical R phenyl are identical or nonidentical and may be selected from the group consisting of

alkyl (linear and branched), alkoxy, fluorine, chlorine, bromine, iodine, aldehyde, ketone, acid ester, acid amide, phosphonic acid derivative, sulfonic acid derivative and mixtures thereof;

(II) is an adduct of trimethylolpropane propoxylate triacrylate and 1H-imidazole derivatives,

R is identical or nonidentical and is selected from the group consisting of

H, methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, tert-butyl, phenyl and/or mono-, di-, tri-, tetra-, pentasubstituted phenyl, where the substituents R phenyl of the phenyl radical are identical or nonidentical and may be selected from the group consisting of

alkyl (linear and branched), alkoxy, —F, —Cl, —Br, —I, aldehyde, ketone, acid ester, acid amide, phosphonic acid derivative, sulfonic acid derivative, and mixtures thereof;

;

(III) is an adduct of pentaerythritol tetraacrylate (PETA) and one or more 1H-imidazole derivatives,

R is identical or nonidentical and is selected from the group consisting of

H, methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, tert-butyl, phenyl and/or mono-, di, tri-, tetra-, pentasubstituted phenyl,

where the substituents of the phenyl radical R phenyl are identical or nonidentical and selected from the group consisting of

alkyl (linear and/or branched), alkoxy, fluorine, chlorine, bromine, iodine, aldehyde, ketone, acid ester, acid amide, phosphonic acid derivative, sulfonic acid derivative, and mixtures thereof;

where R 2 ═H, V of the structure (IV) may be a hydrogen atom or the functional group (V) shown here;

(IV) is an adduct of dipentaerythritol penta/hexaacrylate (DPHA) and one or more 1H-imidazole derivatives, R is identical or nonidentical and is selected from the group consisting of

H, methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, tert-butyl, phenyl and/or mono-, di-, tri-, tetra-, pentasubstituted phenyl, where the substituents on the phenyl radical R phenyl are identical or nonidentical and may be selected from the group consisting of

alkyl (linear and branched), alkoxy, fluorine, chlorine, bromine, iodine, aldehyde, ketone, acid ester, acid amide, phosphonic acid derivative, sulfonic acid derivative, and mixtures thereof, and

R2═H; and

(VI) is a complex compound comprising a metal salt selected from the group consisting of zinc, copper, iron aluminum, and mixtures thereof, and imidazole and/or pyrazole ligands, derived from the structures VIa and VIb

where R1 is identical or nonidentical and

R1 is selected from the group consisting of H-, alkyl-, aryl-, acyl-, cyanoalkyl-, hydroxyalkyl-, cyanoaryl-, hydroxyaryl, and mixtures thereof.

2 . The corona shielding tape as claimed in claim 1 , incorporating multiple tape accelerators.

3 . The corona shielding tape as claimed in claim 2 , wherein the accelerators are incorporated in the polymeric matrix and/or the carrier tape.

4 . The corona shielding tape as claimed in claim 1 , wherein the ligands for the complex salts in accordance with the structure VI are selected from the group of ligands consisting of

1,2-dimethylimidazole (CAS 1739-84-0),

1-decyl-2-methylimidazole,

1-butyl-2-methylimidazole,

1-butyl-2-phenylimidazole,

1H-2-methylimidazole (CAS No. 693-98-1),

1H-imidazole (CAS No. 288-32-4),

1H-2-ethylimidazole (CAS No. 1072-62-4),

1H-2-propylimidazole (CAS No. 50995-94-4),

1H-2-isopropylimidazole (CAS No. 36947-68-9),

1H-2-butylimidazole (CAS No. 50790-93-7),

1H-2-isobutylimidazole (CAS No. 61491-92-7),

1H-2-tert-butylimidazole (CAS No. 36947-69-0),

1H-4-tert-butylimidazole (CAS No. 21149-98-4),

1H-4(5)-methylimidazole (CAS No. 822-36-6),

1H-2-ethyl-4-methylimidazole (CAS No. 931-36-2),

1H-4-methyl-2-phenylimidazole (CAS No. 827-43-0),

1H-4-phenylimidazole (CAS No. 670-95-1),

1H-5-methyl-2-phenylimidazole-4-methanol (CAS No. 13682-32-1),

1H-2,4-dimethylimidazole (CAS No. 930-62-1),

4(5)-(hydroxymethyl)imidazole (CAS No. 822-55-9),

1H-3-phenylpyrazole (CAS No. 2458-26-6),

1H-5-methylpyrazole (no CAS No.),

1H-3,4-dimethylpyrazole (CAS No. 2820-37-3),

1H-3-tert-butylpyrazole (CAS No. 15802-80-9),

1H-4-ethylpyrazole (CAS No. 17072-38-7),

1H-pyrazole (CAS No. 288-3-1),and

1H-3,5-dimethylpyrazole (CAS No. 67-51-6).

5 . The corona shielding tape as claimed in claim 1 , wherein the accelerator is incorporated into the matrix in an amount in the range from 0.1 g/m 2 to 15 g/m 2 .

6 . The corona shielding tape as claimed in claim 1 , wherein the filler embedded in the polymeric matrix comprises globular, planar, tubular filler particles and/or filler mixtures.

7 . The corona shielding tape as claimed in claim 1 , wherein the polymeric matrix comprises more than one polyvinyl alcohol.

8 . The corona shielding tape as claimed in claim 1 , wherein the polymeric matrix comprises at least one polyvinyl alcohol having crosslinked fractions.

9 . The corona shielding tape as claimed in claim 1 , further comprising priming.

10 . The corona shielding tape as claimed in claim 1 comprising a weight of less than 150 g/m 2 .

11 . The corona shielding tape as claimed in claim 1 wherein the carrier tape comprises a coating in an amount in the range from 20 g/m 2 to 100 g/m 2 .

12 . The corona shielding tape as claimed in claim 1 , further comprising filler particles wherein the filler particles are present in the form of hollow bodies, solid particles, coated particles, core-shell particles, and mixtures thereof.

13 . The corona shielding tape as claimed in claim 1 , further comprising electrically conductive filler particles composed of particles selected from the group consisting of carbon black particles, graphite particles, carbon nanotube particles, silicon carbide particles, metal oxide particles and mixtures thereof.

14 - 15 . (canceled)

16 . A corona shielding tape for use to form wound insulation by means of VPI impregnation with a pthalic anhydride-free impregnating epoxy resin, the shielding tape comprising

a carrier tape comprised of

a polymeric matrix comprising at least one polyvinyl alcohol derivative compound having an electrically conductive or semi-conductive filler embedded therein, and

at least one tape accelerator incorporated into the pthalic anhydride-free impregnating epoxy resin, the tape accelerator comprising an adduct of one or more 1H-imidazole derivatives and one or more acrylates selected from the group consisting of trimethylolpropane triacrylate, trimethylolpropane propoxylate triacrylate, pentaerythritol tetraacrylate and dipentaerythritol penta/hexaacrylate.

17 . A corona shielding tape for use to form wound insulation by means of VPI impregnation with a pthalic anhydride-free impregnating epoxy resin, the shielding tape comprising

a carrier tape comprised of

a polymeric matrix comprising at least one polyvinyl alcohol derivative compound having an electrically conductive or semi-conductive filler embedded therein, and

at least one tape accelerator incorporated into the pthalic anhydride-free impregnating epoxy resin, the tape accelerator comprising a complex compound comprising (i) a metal salt selected from the group consisting of zinc, copper, iron, aluminum salts, and mixtures thereof, and (ii) imidazole and/or pyrazole ligands.