| 摘要 |
This invention is a highly insulating film, which is characterized by including a biaxially stretched film containing a styrene polymer having a syndiotactic structure as a main component, containing a thermoplastic amorphous resin Y having a glass transition temperature Tg by DSC of 130° C. or higher in an amount of 5% by mass or more and 48% by mass or less, and having a plane orientation coefficient (AP) represented by the following equation (1) of −0.027 or less: ΔP=(Nx+Ny)/2−Nz (1). In equation (1), Nx represents the minimum value of the refractive index in the plane direction of the film, Ny represents the refractive index in the direction perpendicular to Nx in the plane direction of the film, and Nz represents the refractive index in the thickness direction of the film. |
| 主权项 |
1. A highly insulating film, which is characterized by comprising a biaxially stretched film containing a styrene polymer having a syndiotactic structure as a main component, containing a thermoplastic amorphous resin Y having a glass transition temperature Tg by DSC of 130° C. or higher in an amount of 5% by mass or more and 48% by mass or less, and having a plane orientation coefficient (AP) represented by the following equation (1) of −0.027 or less and −0.040 or more:
ΔP=(Nx+Ny)/2−Nz (1) (in the equation (1), Nx represents the minimum value of the refractive index in the plane direction of the film, Ny represents the refractive index in the direction perpendicular to Nx in the plane direction of the film, and Nz represents the refractive index in the thickness direction of the film), wherein the polymer Y is polyphenylene ether represented by the following formula (A), (each of Q1 and Q2 in the above formula (A) is at least one kind selected from the group consisting of methyl, ethyl and propyl), wherein the film contains an antioxidant in an amount of 0.1% by mass or more and 8% by mass or less relative to the mass of the biaxially stretched film, wherein the content ratio of the polymer Y and the antioxidant (the polymer Y content/the antioxidant content) is 1 to 100, wherein a refractive index in thickness direction of the biaxially stretched film is 1.600 or more and 1.610 or less, and wherein the highly insulating film has a breakdown voltage at 120° C. of 400 V/μm or more. |
