title: Application of the UV laser printing technique to soft gelatin capsules containing titanium dioxide in the shells.
abstract: OBJECTIVE
  The purpose of this study was to examine application of ultraviolet (UV) laser irradiation to printing soft gelatin capsules containing titanium dioxide (TiO(2)) in the shells and to study effect of UV laser power on the color strength of printing on the soft gelatin capsules.
  
  
  METHODS
  Size 6 Oval type soft gelatin capsules of which shells contained 0.685% TiO(2) and 0.005% ferric dioxide were used in this study. The capsules were irradiated pulsed UV laser at a wavelength 355 nm. The color strength of the printed capsules was determined by a spectrophotometer as total color difference (dE).
  
  
  RESULTS
  The soft gelatin capsules which contained TiO(2) in the shells could be printed gray by the laser. Many black particles, which were associated with the printing, were formed at the colored parts of the shells. It was found that there were two inflection points in relationship between output laser energy of a pulse and dE. Below the lower point, the capsules were not printed. From the lower point to the upper point, the capsules were printed gray and total color difference of the printing increased linearly in proportion with the output laser energy. Beyond the upper point, total color difference showed saturation because of micro-bubbles formation at the laser irradiated spot.
  
  
  CONCLUSIONS
  Soft gelatin capsules containing TiO(2) in the shells could be performed stable printing using the UV laser printing technique. Color strength of the printing could be controlled by regulating the laser energy between the two inflection points.
authors: Manufacturing Department Misato Plant, Eisai Co., Ltd., Misato, Kodama, Saitama, Japan.
authors: Akihiro
authors: A
authors: Hosokawa
authors: Yoshiteru
authors: Y
authors: Kato
mesh_terms: D001672:Biocompatible Materials / Q000737:chemistry; D002214:Capsules / Q000737:chemistry*; D003116:Color; D004348:Drug Labeling / Q000379:methods* / Q000592:standards; D005780:Gelatin / Q000737:chemistry*; D007834:Lasers; D008508:Medication Errors / Q000517:prevention & control; D010316:Particle Size; D011327:Printing / Q000379:methods; D014025:Titanium / Q000737:chemistry*; D014466:Ultraviolet Rays
chemical_list: D001672:Biocompatible Materials; D002214:Capsules; C009495:titanium dioxide; D005780:Gelatin; D014025:Titanium