Multi-layer coating method, and planographic printing plate and manufacturing method thereof

A multi-layer coating method for sequentially forming two or more layers, comprising the steps of:

• applying a lower layer onto a continuously traveling web with a first coating device;
• and
• applying an upper layer on the lower layer with a second coating device while the lower layer is undried,
• wherein a non-contact coating system for applying an upper layer coating liquid in a non-contact state with the lower layer is used as the second coating device, and the following equations (B1), (B2) and (B3) are satisfied,
• W/[U(γ1−γ2)]≧0.018 (B1)
• μ1>μ2 (B2)
• W(μ1−μ2)/U≧1.1 (B3)
• wherein W (cc/m2) represents a wet coating amount of the upper layer;
• U (m/min.) represents a traveling speed of the web;
• γ1 (mN/m) represents a dynamic surface tension of the upper layer;
• γ2 (mN/m) represents a static surface tension of the lower layer in contact with the upper layer;
• μ1 (mPa·s) represents a liquid viscosity of the upper layer;
• and μ2 (mPa·s) represents a liquid viscosity of the lower layer in contact with the upper layer.

A multi-layer coating method comprising the step of simultaneously forming two or more layers with one coating device of a slide bead type and a slide curtain type having a slide surface on a continuously traveling web,

• wherein the following equation (A1) is satisfied,
• W/[U(γ1−γ2)]≧0.018 (A1)
• wherein W (cc/m2) represents a wet coating amount of the upper layer;
• U (m/min.) represents a traveling speed of the web;
• γ1 (mN/m) represents a dynamic surface tension of the upper layer;
• and γ2 (mN/m) represents a static surface tension of the lower layer in contact with the upper layer.

A multi-layer coating method comprising the step of simultaneously forming two or more layers with one coating device of a slide bead type and a slide curtain type having a slide surface on a continuously traveling web,

• wherein the following equations (B1), (B2) and (B3) are satisfied,
• W/[U(γ1−γ2)]≧0.018 (B1)
• μ1>μ2 (B2)
• W(μ1−μ2)/U≧1.1 (B3)
• wherein W (cc/m2) represents a wet coating amount of the upper layer;
• U (m/min.) represents a traveling speed of the web;
• γ1 (mN/m) represents a dynamic surface tension of the upper layer;
• γ2 (mN/m) represents a static surface tension of the lower layer in contact with the upper layer;
• μ1 (mPa·s) represents a liquid viscosity of the upper layer;
• and μ2 (mPa·s) represents a liquid viscosity of the lower layer in contact with the upper layer.