Fluidized-bed coating method and fluidized-bed coating apparatus

Patent metadata

Field	Value
Publication number	US-11794208-B2
Application number	US-202016932855-A
Country	US
Kind code	B2
Filing date	Jul 20, 2020
Priority date	Mar 27, 2020
Publication date	Oct 24, 2023
Grant date	Oct 24, 2023

Abstract

A fluidized-bed coating method includes: immersing at least part of a workpiece in a powder coating material contained in a fluidized-bed vessel while air is introduced from a bottom of the fluidized-bed vessel at an average air flow rate of 5 mm/min or higher and 20 mm/min or lower per unit area of the bottom so that a floating ratio of the powder coating material is 5% or higher and 20% or lower, the workpiece having a temperature higher than or equal to a softening temperature of the powder coating material and lower than or equal to a melting temperature of the powder coating material; taking the workpiece out of the powder coating material; and heating the powder coating material attached to the workpiece.

First claim

What is claimed is:

1. A fluidized-bed coating method comprising:
immersing at least part of a workpiece in a powder coating material contained in a fluidized-bed vessel while air is introduced from a bottom of the fluidized-bed vessel at an average air flow rate of 5 mm/min or higher and 20 mm/min or lower per unit area of the bottom so that a floating ratio of the powder coating material is 5% or higher and 20% or lower;
taking the workpiece out of the powder coating material; and
heating the powder coating material attached to the workpiece,
wherein when the at least part of the workpiece is immersed in the powder coating material, a surface temperature of an immersed portion of the workpiece decreases by at least 5° C. from a preheating temperature due to conveyance before the immersion and heat conduction to contact particles of the powder coating material during the immersion, and is then maintained in a range of from a softening temperature of the powder coating material to a melting temperature of the powder coating material for at least 5 seconds after the immersion,
wherein the softening temperature of the powder coating material is a glass transition temperature of the powder coating material and is in a range of 45° C. to 70° C., and the melting temperature of the powder coating material is in a range of 80° C. to 180° C.,
wherein the powder coating material has a volume average particle diameter D50v of 5 μm or more and 20 μm or less,
wherein the workpiece is preheated to the preheating temperature before the conveyance and the immersion, and the preheating temperature is set in a range of from a temperature 20° C. higher than the softening temperature of the powder coating material to a temperature 5° C. higher than the melting temperature of the powder coating material.

2. The fluidized-bed coating method according to claim 1 , wherein an immersion time for the at least part of the workpiece is 5 seconds or longer and 10 seconds or shorter.

3. The fluidized-bed coating method according to claim 1 , wherein the powder coating material has an aerated flowability energy AE of 5 mJ or higher and lower than 100 mJ, where the AE is measured with a powder rheometer using a vessel having a cross-sectional area with Ø 50 mm under conditions of a rotary blade tip speed of 100 mm/sec, a rotary blade helix angle of −5°, and an air flow rate of 20 ml/min.

4. The fluidized-bed coating method according to claim 1 , wherein the powder coating material has a volume particle size distribution index GSDv of 1.15 or higher and 1.40 or lower.

5. The fluidized-bed coating method according to claim 4 , wherein the powder coating material has a volume particle size distribution index GSDv of 1.15 or higher and 1.25 or lower.

6. The fluidized-bed coating method according to claim 1 , wherein the floating ratio is 10% or higher and 20% or lower.

7. The fluidized-bed coating method according to claim 1 , wherein the powder coating material includes powder particles and an external additive on the powder particles.

8. The fluidized-bed coating method according to claim 7 , wherein the external additive is a hydrophobic external additive.

9. The fluidized-bed coating method according to claim 7 , wherein the external additive has a volume average particle diameter of 5 nm or more and 30 rim or less.

Assignees

• Fujifilm Business Innovation Corp

Inventors

• Furuki Makoto
• Yoshino Susumu
• Saegusa Hiroshi
• Yoshida Satoshi

Classifications

• B05D1/24 Primary

  Applying particulate materials · CPC title

• B05C3/04

  with special provision for agitating the work or the liquid or other fluent material · CPC title

• B05C3/09

  for treating separate articles · CPC title

• B05C11/045

  characterised by the blades themselves · CPC title

• B05C19/02 Primary

  using fluidised-bed techniques (fluidised-bed technique in general B01J8/24) · CPC title