Composite coating film, heat exchanger comprising same, and method for manufacturing heat exchanger

A manufacturing method of a fin and tube type heat exchanger, the manufacturing method comprising:

• performing roll coating and heat drying on a metallic material to form a first coating layer;
• performing roll coating and heat drying on the first coating layer to form a second coating layer;
• and
• manufacturing the metallic material on which the first coating layer and the second coating layer are formed into a plurality of fins, and inserting a tube into at least one of the plurality of fins,
• wherein the first coating layer includes:
• 10-40 wt % of a first hydrophilic resin,
• 1-20 wt % of a metal compound,
• 5-20 wt % of an amide-based cross linker,
• 1-15 wt % of a silane compound, and
• water as a remaining component, and
• the second coating layer includes:
• 1-20 wt % of a second hydrophilic resin,
• 1-20 wt % of a silica particle,
• 0.01-5 wt % of a cross linker,
• 0.1-5 wt % of a solvent, and
• water as a remaining component.

A manufacturing method of a microchannel type heat exchanger, the manufacturing method comprising:

• dipping the microchannel type heat exchanger in a first coating composition having corrosion resistance and hydrophilicity, and forming a first coating layer;
• immersing the microchannel type heat exchanger at which the first coating layer is formed in a second coating composition having hydrophilicity, and forming a second coating layer;
• air blowing a lower end portion of the microchannel type heat exchanger;
• and
• drying the microchannel type heat exchanger,
• wherein the first coating composition includes:
• 10-40 wt % of a first hydrophilic resin,
• 1-20 wt % of a metal compound,
• 5-20 wt % of an amide based cross linker
• 1-15 wt % of a silane compound, and
• water as a remaining component and
• the second coating composition includes:
• 1-20 wt % of a second hydrophilic resin,
• 1-20 wt % of a silica particle,
• 0.01-5 wt % of a cross linker,
• 0.1-5 wt % of a solvent, and
• water as a remaining component.

A microchannel type heat exchanger comprising:

• a plurality of flat tubes that have a plurality of flow paths therein;
• a fin that is connected to at least one of the flat tubes and transfers heat therefrom;
• and
• wherein a complex coating film is formed at one or more of the fin or at least one of the plurality of flat tubes,
• wherein the complex coating film includes a first coating layer that has corrosion resistance and hydrophilicity, and a second coating layer of the complex coating film that has hydrophilicity,
• wherein the first coating layer includes:
• 10-40 wt % of a first hydrophilic resin
• 1-20 wt % of a metal compound,
• 5-20 wt % of an amide-based cross linker,
• 1-15 wt % of a silane compound, and
• water as a remaining component and
• the second coating layer includes:
• 1-20 wt % of a second hydrophilic resin
• 1-20 wt % of a silica particle,
• 0.01-5 wt % of a cross linker
• 0.1-5 wt % of a solvent, and
• water as a remaining component.