Separator with heat-resistant insulation layer

1. A separator with a heat-resistant insulation layer, comprising:

a resin porous substrate; and

a heat-resistant insulation layer containing heat-resistant particles and a binder, the heat-resistant insulation layer being formed on at least one surface of the resin porous substrate,

wherein the heat-resistant particles are alumina particles that contain α alumina,

a mass ratio of the heat-resistant particles to the binder is 95:5,

a secondary particle diameter of the heat-resistant particles is 500 nm to 3 μm, and

a parameter X represented by a following mathematical expression (1) is 0.018 to 0.336:

X=C α ×R zjis /D   (1)

where C α is a relative value of a peak area of the α alumina in a case where a peak area of a whole of the heat-resistant particles is defined as 1, the peak area being measured by an X-ray diffraction analysis, R zjis is a ten-point average surface roughness (μm) of a surface of the heat-resistant insulation layer, the surface opposing a surface of the resin porous substrate, and D is a thickness (μm) of the heat-resistant insulation layer, and

the surface roughness R zjis is 1.3 to 2.97 μm.

2. The separator with a heat-resistant insulation layer according to claim 1 , wherein the parameter X is 0.04 to 0.33.

3. The separator with a heat-resistant insulation layer according to claim 1 , wherein the parameter X is 0.07 to 0.30.

4. The separator with a heat-resistant insulation layer according to claim 1 , wherein the C α is 0.06 or more.

5. The separator with a heat-resistant insulation layer according to claim 1 , wherein a parameter Y represented by a following mathematical expression (2) is 5.6 to 99:

Y=A/B   (2)

where A is a mass (g) of the heat-resistant particles, and B is a mass (g) of the binder.

6. An electric device, wherein the electric device is interposed between a positive electrode and a negative electrode, and includes the separator with a heat-resistant insulation layer according to claim 1 .