Mica sheet and tape
View Patent ↗The present invention relates to a sheet structure for electrical insulation or flame resistance comprising a barrier ply having a mica-rich face and a mica-poor face and a reinforcing ply containing a saturable backing layer attached to the mica-poor face of the barrier ply.
1. A sheet structure comprising:
(a) a barrier ply containing a mica-rich face and a mica-poor face, and
(b) a reinforcing ply comprising a saturable backing layer, said reinforcing ply attached to the mica-poor face of the barrier ply.
2. The sheet structure of claim 1 , wherein mica content is at least 30 weight percent of the total composition of the sheet structure.
3. The sheet structure of claim 1 wherein the barrier ply has, in addition to mica, an aramid material.
4. The sheet structure of claim 1 wherein the mica-rich face of the barrier ply has at least 60 percent mica by weight based on the total components in the mica-rich face and the mica-poor face contains less than 40 percent mica by weight based on the total components in the mica-poor face.
5. The sheet structure of claim 1 wherein the mica-rich face of the barrier ply has at least 85 percent mica by weight based on the total components in the mica-rich face and the mica-poor face contains less than 10 percent mica by weight based on the total components in the mica-poor face.
6. A mica-based tape comprising the sheet structure of claim 2 .
7. A prepreg comprising the sheet structure of claim 2 and a matrix resin.
8. The sheet structure of claim 2 , wherein the saturable backing layer of the reinforcing ply is a spunlaced aramid material.