Aluminum flake pigment

Abstract

An aluminium flake pigment characterized in that the ratio of the average thickness of flakes to the average diameter of flakes is in the range of 0.025 to 0.3, preferably 0.028 to 0.1 and the ratio of the water covering area to the specific surface area is in the range of 0.18 to 0.4, preferably 0.19 to 0.35 is disclosed herein. The aluminium flake pigment of the invention has the improved resistance to the circulation of the metallic paint during the painting.

I claim: 
     
       1. An aluminum flake pigment wherein the ratio of the average thickness of flakes to the average diameter of flakes is in the range of 0.025 to 0.3 and the ratio of the water covering area to the specific surface area is in the range of 0.18 to 0.4. 
     
     
       2. The pigment as claimed in claim 1 wherein the ratio of the average thickness of flakes to the average diameter of flakes is in the range of 0.028 to 0.1. 
     
     
       3. The pigment as claimed in claim 1, wherein the ratio of the water covering area to the specific surface area is in the range of 0.19 to 0.35. .Iadd. 
     
     
       4.  An aluminum flake pigment, wherein the ratio of the average thickness of flakes to the average diameter of flakes is in the range of 0.025 to 0.3 and the ratio of the water covering area to the specific surface area is in the range of 0.18 to 0.4, wherein the flakes have a sufficiently uniform thickness to orient the flakes regularly in a painted sheet..Iaddend..Iadd.5. An aluminum flake pigment, wherein the ratio of the average thickness of flakes to the average diameter of flakes is in the range of 0.025 to 0.3 and the ratio of the water covering area to the specific surface area is in the range of 0.18 to 0.4, which flakes orient regularly in a painted sheet..Iaddend..Iadd.6. An aluminum flake pigment, wherein the ratio of the average thickness of flakes to the average diameter of flakes is in the range of 0.025 to 0.3 and the ratio of the water covering area to the specific surface area is in the range of 0.18 to 0.4, the flakes having a uniform thickness and shape which essentially eliminates bent or ruptured flakes caused by paint circulation..Iaddend..Iadd.7. The aluminum flake pigment of claim 4, 5 or 6, wherein after paint circulation the flakes retain at least 93% brightness..Iaddend..Iadd.8. The pigment of claim 7, wherein the retained 
     
     
        brightness is between about 93% and 99%..Iaddend..Iadd.9.  The aluminum flake pigment of claim 1, wherein the flakes orient regularly, as observed by scanning electron microscope, when applied in a paint film made in the following manner: (a) 34.3 parts by weight of the aluminum flake pigment are mixed with 160.0 parts by weight of acrylic resin containing 50.0% by weight of dry matter and 33.3 parts by weight of melamine resin containing 60% by weight of dry matter, to form a paint;   (b) viscosity of the paint is adjusted to 20 to 21 seconds on Ford cup #4, with a mixed solvent of ethyl acetate, butyl acetate, xylene, aromatic solvent having a typical flashpoint of 49 degrees C. and CH 2  COOCH 2  CH 2  OOC 2  H 5  (mixed ratio by volume=30:10:30:20:10);   (c) 300 g of the viscosity-adjusted paint is charged into a vessel provided with a jacket for circulating cooling water and stirred by a stirrer with turbine blades for 1 hour;   (d) the paint is sprayed on polished mild steel sheet to form a paint film having a thickness of about 20 μm; and   (e) the paint film is baked at 140° C. for 30 minutes..Iaddend.