Precoated fin material for heat exchangers and heat exchanger

Abstract

Provided is a precoated fin material for heat exchangers that allows the construction of a fin structure in which frost formation at the time of heater operation can be prevented to the extent possible, and under such a condition that condensation is liable to occur on a fin surface, a water droplet of condensed water can be quickly removed by bringing the water droplet into contact with a hydrophilic film, and as a result, a favorable heat exchange function can be maintained without any increase in ventilation resistance. Also provided is a heat exchanger including such fin structure. The precoated fin material for heat exchangers includes: a fin substrate formed of an aluminum plate material; a crosslinked hydrophobic film having a frost formation-suppressing effect, the crosslinked hydrophobic film being formed on one surface of the fin substrate and being formed of an aqueous hydrophobic coating composition containing a resin (A) having a fluorine atom-containing group, a quaternary ammonium salt group-containing modified epoxy resin (B), and an amino resin (C) at predetermined ratios; and a hydrophilic film having a condensed water-removing effect, the hydrophilic film being formed on another surface of the fin substrate. The heat exchanger includes a fin structure in which a hydrophobic surface having a frost formation-suppressing effect and a hydrophilic surface having a condensed water-removing effect are opposite to each other.

1 . A precoated fin material for heat exchangers, comprising:
 a fin substrate formed of an aluminum plate material formed of aluminum or an aluminum alloy;   a crosslinked hydrophobic film having a frost formation-suppressing effect, the crosslinked hydrophobic film being formed on one surface of the fin substrate; and   a hydrophilic film having a condensed water-removing effect, the hydrophilic film being formed on another surface of the fin substrate,   wherein the crosslinked hydrophobic film is formed of an aqueous hydrophobic coating composition containing a resin (A) having at least one kind of fluorine atom-containing group selected from the group consisting of a perfluoroalkyl group and a perfluoroalkenyl group, a quaternary ammonium salt group-containing modified epoxy resin (B), and an amino resin (C) in which a solid content of the resin (A) having at least one kind of fluorine atom-containing group selected from the group consisting of a perfluoroalkyl group and a perfluoroalkenyl group is 1 to 30 parts by mass with respect to 100 parts by mass of a total of solid contents of the quaternary ammonium salt group-containing modified epoxy resin (B) and the amino resin (C).   
     
     
         2 . A precoated fin material for heat exchangers according to  claim 1 , wherein the crosslinked hydrophobic film is formed on one of anticorrosive films formed on both surfaces of the fin substrate. 
     
     
         3 . A precoated fin material for heat exchangers according to  claim 1  or  2 , wherein the crosslinked hydrophobic film has a water contact angle of 100° or more. 
     
     
         4 . A precoated fin material for heat exchangers according to  claim 1 , wherein the hydrophilic film has a water contact angle of 40° or less. 
     
     
         5 . A precoated fin material for heat exchangers according to  claim 1 , wherein the crosslinked hydrophobic film is formed by baking the aqueous hydrophobic coating composition after application thereof and has a thickness of 0.05 to 5.0 μm. 
     
     
         6 . A precoated fin material for heat exchangers according to  claim 1 , wherein the hydrophilic film is formed by baking a hydrophilic coating material after application thereof and has a thickness of 0.05 to 5.0 μm. 
     
     
         7 . A heat exchanger, comprising a fin structure in which a large number of flat precoated fin materials are placed at a predetermined interval to be parallel to each other, and a hydrophobic surface having a frost formation-suppressing effect and a hydrophilic surface having a condensed water-removing effect are opposite to each other between precoated fin materials adjacent to each other,
 wherein:   the large number of precoated fin materials include of a large number of one-side hydrophobic/one-side hydrophilic fin materials each having, on one surface of a fin substrate formed of an aluminum plate material formed of aluminum or an aluminum alloy, a crosslinked hydrophobic film forming the hydrophobic surface and each having, on another surface thereof, a hydrophilic film forming the hydrophilic surface, or include a plurality of double-side hydrophobic fin materials each having, on each of both surfaces of a fin substrate formed of an aluminum plate material formed of aluminum or an aluminum alloy, a crosslinked hydrophobic film forming the hydrophobic surface and a plurality of double-side hydrophilic fin materials each having, on each of both surfaces of a fin substrate formed of an aluminum plate material formed of aluminum or an aluminum alloy, a hydrophilic film forming the hydrophilic surface; and   the crosslinked hydrophobic film is formed of an aqueous hydrophobic coating composition containing a resin (A) having at least one kind of fluorine atom-containing group selected from the group consisting of a perfluoroalkyl group and a perfluoroalkenyl group, a quaternary ammonium salt group-containing modified epoxy resin (B), and an amino resin (C) in which a solid content of the resin (A) having at least one kind of fluorine atom-containing group selected from the group consisting of a perfluoroalkyl group and a perfluoroalkenyl group is 1 to 30 parts by mass with respect to 100 parts by mass of a total of solid contents of the quaternary ammonium salt group-containing modified epoxy resin (B) and the amino resin (C).   
     
     
         8 . A heat exchanger according to  claim 7 , wherein the large number of precoated fin materials include of the large number of one-side hydrophobic/one-side hydrophilic fin materials. 
     
     
         9 . A heat exchanger according to  claim 7 , wherein the large number of precoated fin materials include the plurality of double-side hydrophobic fin materials and the plurality of double-side hydrophilic fin materials. 
     
     
         10 . A precoated fin material for heat exchangers according to  claim 2 , wherein the hydrophilic film has a water contact angle of 40° or less. 
     
     
         11 . A precoated fin material for heat exchangers according to  claim 3 , wherein the hydrophilic film has a water contact angle of 40° or less. 
     
     
         12 . A precoated fin material for heat exchangers according to  claim 2 , wherein the crosslinked hydrophobic film is formed by baking the aqueous hydrophobic coating composition after application thereof and has a thickness of 0.05 to 5.0 μm. 
     
     
         13 . A precoated fin material for heat exchangers according to  claim 3 , wherein the crosslinked hydrophobic film is formed by baking the aqueous hydrophobic coating composition after application thereof and has a thickness of 0.05 to 5.0 μm. 
     
     
         14 . A precoated fin material for heat exchangers according to  claim 4 , wherein the crosslinked hydrophobic film is formed by baking the aqueous hydrophobic coating composition after application thereof and has a thickness of 0.05 to 5.0 μm. 
     
     
         15 . A precoated fin material for heat exchangers according to  claim 2 , wherein the hydrophilic film is formed by baking a hydrophilic coating material after application thereof and has a thickness of 0.05 to 5.0 μm. 
     
     
         16 . A precoated fin material for heat exchangers according to  claim 3 , wherein the hydrophilic film is formed by baking a hydrophilic coating material after application thereof and has a thickness of 0.05 to 5.0 p.m. 
     
     
         17 . A precoated fin material for heat exchangers according to  claim 4 , wherein the hydrophilic film is formed by baking a hydrophilic coating material after application thereof and has a thickness of 0.05 to 5.0 μm.