Electrical insulation paper, methods of manufacture, and articles manufactured therefrom

An electrical paper comprising

• a fibrous substrate having a first side and a second side opposite the first side, and comprising a consolidated product of a fiber composition comprising:
• about 20 to 65 wt. % of polyimide fibers;
• about 30 to 70 wt. % of aromatic polyamide fibers;
• about 10 to 30 wt. % aromatic polyamide fibrids;
• each based on the total weight of these fibers in the fiber composition;
• and having
• a first layer comprising about 75 to 95 wt. % polyimide fibers and about 5 to 25 wt. % aromatic polyamide fibrids disposed on the first side of the fibrous substrate;
• and
• a second layer comprising about 75 to 95 wt. % polyimide fibers and about 5 to 25 wt. % aromatic polyamide fibrids disposed on the second side of the fibrous substrate,
• wherein the electrical paper has a thickness of from more than 0 to less than 8 mil.

An electrical paper comprising

• a fibrous substrate having a first side and a second side opposite the first side, and comprising a consolidated product of a fiber composition comprising:
• about 75 to 95 wt. % polyimide fibers and about 5 to 25 wt. % aromatic polyamide fibrids each based on the total weight of these fibers in the fiber composition;
• a first layer comprising:
• about 35 to 45 wt. % of polyimide fibers;
• about 35 to 45 wt. % of aromatic polyamide fibers;
• about 10 to 30 wt. % aromatic polyamide fibrids;
• disposed on the first side of the fibrous substrate;
• and
• a second layer comprising:
• about 35 to 45 wt. % of polyimide fibers;
• about 35 to 45 wt. % of aromatic polyamide fibers;
• about 10 to 30 wt. % aromatic polyamide fibrids;
• disposed on the second side of the fibrous substrate,
• wherein the electrical paper has a thickness of from more than 0 to less than 80 mil.

A process of preparing a fibrous substrate, comprising

• forming a layer from a slurry comprising
• a suspension solvent;
• and fiber composition comprising a combination of
• about 20 to 65 wt. % of polyimide fibers;
• about 30 to 70 wt. % of aromatic polyamide fibers;
• about 10 to 30 wt. % aromatic polyamide fibrids;
• each based on the total weight of the fibers in the fiber composition;
• dewatering the layer;
• and
• consolidating the layer to form the fibrous substrate;
• wherein a layer of about 75 to 95 wt. % polyimide fiber and 5 to 25 wt. % aromatic polyamide fibrid is applied to each surface of the fibrous substrate either before or after said consolidating step, and the substrate and polyimide layers are together subjected to a consolidating step.