Preparation method and preparation apparatus of separation membrane for electrochemical device

1. A preparation method of a separator for an electrochemical device, the preparation method comprising:

supplying a porous separator substrate;

coating a first coating agent and a second coating agent on one surface of the porous separator substrate by a first coating part of a die coating method that includes a first roller;

coating a third coating agent directly on the other surface of the porous separator substrate by a second coating part of a roll coating method that includes a second roller; and

forming a first coating layer, a second coating layer, and a third coating layer by drying the porous separator substrate coated with the first coating agent, the second coating agent, and the third coating agent,

wherein a pattern is formed on a surface of the second roller,

wherein the third coating agent does not include inorganic particles,

wherein the roll coating method of the second coating part is a direct metering coating method,

wherein the second roller is a roller having continuous or discontinuous projections on a surface of a roller body,

wherein the projections are in a pattern having a straight line shape,

wherein the straight line shape projections include a shape symmetrically tilted with reference to a vertical center in a length direction of the roller,

wherein the projections are tilted in a shape of an oblique line that is inclined by 45 degrees to both ends with reference to a vertical center in a length direction of the roller,

wherein the projections form a flow path for the third coating agent,

wherein a portion of the porous separator substrate that is in contact with the pattern formed on a surface of the second roller is sunken into the groove, preventing a meandering phenomenon of the porous separator substrate and preventing non-uniformity of a surface of the third coating layer.

2. The preparation method of claim 1 , wherein the first coating agent and the second coating agent are coated on one surface of the porous separator substrate, and the third coating agent is coated on the other surface of the porous separator substrate, respectively, while the porous separator substrate is moved at a velocity of 40 m/min or higher within a system isolated from outside.

3. The preparation method of claim 1 , wherein at least one of the projections and the wire are formed from an anti-slip material.

4. The preparation method of claim 1 , wherein surfaces of the projections and the wire are independently in a plane shape or a concave shape.

5. The preparation method of claim 1 , wherein the porous separator substrate is composed of polyolefin-based polymer.

6. The preparation method of claim 1 , wherein the first coating agent comprises an inorganic particle, a first binder polymer, and a first solvent, and the second coating agent comprises a second binder polymer and a second solvent, and the third coating agent comprises a third binder polymer and a third solvent.

7. The preparation method of claim 1 , wherein the first coating layer has a density of 0.5 g/cm 3 to 6.0 g/cm 3 , and a thickness of 2 μm to 10 μm.

8. The preparation method of claim 1 , wherein the second coating layer and the third coating layer independently have a thickness of 0.1 μm to 3 μm.