Removal Method and Removal Apparatus for Entrained Air in Coating Fluid

Abstract

The present invention has as an object to render a photochromic coating layer free from air bubbles and obtain a uniform layer without film thickness unevenness in the coating layer. In the prevent invention, entrained air in a coating fluid stored in a vessel of a coating unit comprising the vessel, a check valve for preventing back-flow of the coating fluid connected to the vessel, and optionally an ejection nozzle connected to the check valve; air existing inside of the check valve; and optionally air existing inside of the ejection nozzle are removed by plugging an outlet of the coating fluid existing downstream of the check valve and then rotating the coating unit on an axis of the vessel and orbiting the coating unit on a revolution axis simultaneously.

1 . A method for removing air from a coating fluid containing entrained air comprising the steps of:
 (A) preparing a coating unit comprising a cylindrical vessel storing the coating fluid and a check valve for preventing back-flow of the coating fluid connecting with the vessel;   (B) plugging an outlet of the coating fluid existing downstream of the check valve; and   (C) rotating the coating unit on an axis of the vessel and orbiting the coating unit on a revolution axis simultaneously whereby introducing the coating fluid into the check valve, discharging air resided inside of the check valve toward the vessel, and further removing air incorporated in the coating fluid from the coating fluid.   
   
   
       2 . The method according to  claim 1 , wherein the coating unit prepared in the step (A) further contains an ejection nozzle for ejecting the coating fluid connecting with the check valve, the plugging in the step (B) is carried out by plugging an outlet of the ejection nozzle, and the coating fluid is introduced into the check valve and the ejection nozzle, and the air inside the check valve and the air inside the ejection nozzle are discharged toward the vessel in the step (C). 
   
   
       3 . The method according to  claim 1 , wherein a rotational speed of revolution of the coating unit is set such that the speed in a late stage of a rotating operation is rendered higher than the speed in an early stage of the rotating operation. 
   
   
       4 . The method according to  claim 1 , wherein the coating fluid is a photochromic coating fluid to be coated on a surface of spectacles. 
   
   
       5 . A removal apparatus for entrained air in a coating fluid, the apparatus comprises a casing which can rotate on a rotation axis and also can orbit on revolution axis, and a coating unit comprising a cylindrical vessel accommodating a coating fluid inside, a check valve for preventing back-flow of the coating fluid connecting the vessel and a lid for plugging an outlet of the coating fluid existing downstream of the check valve; wherein
 the rotation axis being located, with respect to the revolution axis, outwardly and downwardly in a circumferential direction of an orbital on the revolution axis,   the coating unit being supported by the casing detachably such that the lid of the coating unit is located below, and   the coating unit being rotated on the rotation axis and being orbit on the revolution axis simultaneously with the casing, to discharge air resided inside of the check valve toward the vessel, and further to remove air incorporated in the coating fluid.   
   
   
       6 . The removal apparatus for entrained air in a coating fluid according to  claim 5 , wherein
 the coating unit further contains an ejection nozzle for ejecting the coating fluid connecting with the check valve, and   the lid is mounted on a tip portion of the ejection nozzle.   
   
   
       7 . The removal apparatus for entrained air in a coating fluid according to  claim 5 , wherein the coating fluid is a photochromic coating fluid to be coated on a surface of spectacles. 
   
   
       8 . The removal apparatus for entrained air in a coating fluid according to  claim 5 , wherein
 a flange facing outward is formed on a periphery of the vessel, and   the flange is detachably mounted on the casing.