Fin material and heat exchanger

Abstract

A heat-exchanger fin material (1) has a coating film (3) formed on at least one surface of an aluminum substrate (2). An outermost surface of the coating film (3) is a positively-chargeable coating (31) that is essentially composed of only one or more resins selected from the group consisting of cellulose-based resins, acrylic-based resins, vinyl alcohol-based resins, acrylamide-based resins, and ester-based resins. The surface roughness Ra of the coating film (3) is 100 nm or less. A heat exchanger (5) includes a plurality of fins composed of the fin material (1) and at least one metal tube (7) passing through the plurality of fins (1).

1 . A heat-exchanger fin material comprising:
 a substrate composed of aluminum; and   a coating film formed on at least one surface of the substrate and composed of a coating having one layer or two or more layers;   wherein the coating film has a positively-chargeable coating on its outermost surface;   the positively-chargeable coating is essentially composed of only at least one resin selected from the group consisting of cellulose-based resins, acrylic-based resins, vinyl alcohol-based resins, acrylamide-based resins, and ester-based resins; and   the surface roughness Ra of the coating film is 100 nm or less.   
     
     
         2 . The heat-exchanger fin material according to  claim 1 , wherein the surface roughness Ra of the coating film is 50 nm or less. 
     
     
         3 . The heat-exchanger fin material according to  claim 1 , wherein the surface roughness Ra of the coating film is 20 nm or less. 
     
     
         4 . The heat-exchanger fin material according to  claim 1 , wherein the water-contact angle on the surface of the coating film is 40° or less. 
     
     
         5 . The heat-exchanger fin material according to  claim 1 , wherein the water-contact angle on the surface of the coating film is 30° or less. 
     
     
         6 . The heat-exchanger fin material according to  claim 1 , wherein the film thickness of the positively-chargeable coating is 0.1-6 μm. 
     
     
         7 . A heat exchanger comprising:
 a fin composed of the heat-exchanger fin material according to  claim 1 .   
     
     
         8 . The heat-exchanger fin material according to  claim 3 , wherein:
 the water-contact angle on the surface of the coating film is 30° or less, and   the film thickness of the positively-chargeable coating is 0.1-6 μm.   
     
     
         9 . The heat-exchanger fin material according to  claim 8 , wherein the film thickness of the positively-chargeable coating is 0.5-1.5 μm. 
     
     
         10 . The heat-exchanger fin material according to  claim 9 , wherein at least 99 mass % of the positively-chargeable coating is composed of one or more of carboxymethyl cellulose, polyacrylic acid, polyacrylamide, polyvinyl alcohol, and/or polyester. 
     
     
         11 . A fin comprising:
 a substrate composed of pure aluminum or an aluminum alloy; and   a coating film formed on at least one surface of the substrate and composed of a coating having one layer or two or more layers;   wherein an outermost layer of the coating film consists essentially of one or more resins selected from the group consisting of cellulose-based resins, acrylic-based resins, vinyl alcohol-based resins, acrylamide-based resins, and ester-based resins; and   the coating film has an average surface roughness Ra of 100 nm or less.   
     
     
         12 . The fin according to  claim 11 , wherein:
 the coating film exhibits a water-contact angle of 40° or less, and   the coating film has a thickness of 0.1-6 μm.   
     
     
         13 . The fin according to  claim 12 , wherein the average surface roughness Ra of the coating film is 50 nm or less. 
     
     
         14 . The fin according to  claim 13 , wherein at least 99 mass % of the outermost layer of the coating film is composed of one or more compound(s) selected from the group consisting of carboxymethyl cellulose, polyacrylic acid, polyacrylamide, polyvinyl alcohol, and polyester. 
     
     
         15 . The fin according to  claim 13 , wherein at least 99.5 mass % of the outermost layer of the coating film is composed of one or more compound(s) selected from the group consisting of carboxymethyl cellulose, polyacrylic acid, polyacrylamide, polyvinyl alcohol, and polyester. 
     
     
         16 . The fin according to  claim 15 , wherein the coating film has a surface electric potential of +0.01 V to +10 V. 
     
     
         17 . The fin according to  claim 16 , wherein the thickness of the coating film is 0.5-1.5 μm. 
     
     
         18 . The fin according to  claim 17 , wherein:
 the coating film exhibits a water-contact angle of 30° or less, and   the average surface roughness Ra of the coating film is 20 nm or less.   
     
     
         19 . A heat exchanger comprising:
 a plurality of fins according to  claim 18 ; and   a metal tube passing through holes in the plurality of fins and in contact with the plurality of fins.   
     
     
         20 . A heat exchanger comprising:
 a plurality of fins according to  claim 11 ; and   a metal tube passing through holes in the plurality of fins and in contact with the plurality of fins.