Tape comprising a hybrid binder for high voltage application
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.
1 . A tape consisting essentially of mica, a separate solid support and a resin component Z, the resin component Z comprising:
i. one or more, the same or different, groups of formula
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
iii. one or more groups comprising two ester groups and one ethylenically unsaturated group;
wherein the resin component Z has an acid value of not more than 25 mgKOH/g.
2 . The tape of claim 1 , wherein the resin component Z consists essentially of:
i. one or more, the same or different, groups of formula
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
iii. one or more groups comprising two ester groups and one ethylenically unsaturated group.
3 . The tape of claim 1 , wherein R comprises a hydrocarbon part of a bisphenol A unit or a bisphenol F unit.
4 . 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 ester.
5 . The tape of claim 1 , 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.
6 . The tape of claim 1 , 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.
7 . The tape of claim 6 , wherein the epoxy resin further comprises one or more of bisphenol A and bisphenol F.
8 . A substrate comprising a metal and the tape of claim 1 .
9 . The tape of claim 1 , wherein the acid value of the resin component Z is not more than 20 mgKOH/g.
10 . A process for preparing a tape, the process comprising:
providing a material comprising mica, a separate solid support and a resin component Z, the resin component Z comprising:
i. one or more, the same or different, groups of formula
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;
iii. one or more groups comprising two ester groups and one ethylenically unsaturated group; and
bonding the material comprising mica and the solid support with the resin component Z to form a tape consisting essentially of said mica, said separate solid support, and said resin component Z,
wherein the resin component Z has an acid value of not more than 25 mgKOH/g.
11 . The process of claim 10 , 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.
12 . The process of claim 10 , wherein the acid value of the resin component Z is not more than 20 mgKOH/g.
13 . 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 consisting essentially of mica and a separate 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
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 composition to form a cured resin composition;
wherein the cured resin composition has an acid value of not more than 25 mgKOH/g.
14 . A treated substrate obtained by the process of claim 13 .
15 . The process of claim 13 , 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.
16 . The process of claim 13 , wherein the acid value of the cured resin composition is not more than 20 mgKOH/g.