title: Studies on the mechanism of printing film-coated tablets containing titanium dioxide in the film by using UV laser irradiation.
abstract: OBJECTIVE
  The purpose of this article is to study a detailed mechanism of printing when film-coated tablets were irradiated by UV laser at a wavelength of 355 nm.
  
  
  METHODS
  Hydroxypropylmethylcellulose (HPMC) film containing titanium dioxide (TiO(2)) and the film not containing TiO(2) and TiO(2) powder were lirradiated by the UV laser and estimated by the morphological observation by zoom stereo microscope, thermogravimetric analysis (TGA), total color difference (dE), X-ray powder diffraction (XRD), and dispersive Raman microscopy.
  
  
  RESULTS
  In the case of the film containing TiO(2), the film showed a visible change in its color from white to gray by the UV laser irradiation. By zoom stereo microscope, it was found that the entire UV laser-irradiated area was not grayed uniformly, but many black particles, whose diameter was about 2 microm, were observed on the film. When TiO(2) powder was irradiated by the UV laser, a visible change in its color from white to gray was observed similar to the case of the film containing TiO(2). There were many black particles locally in the UV laser-treated TiO(2) powder by the morphological observation, and these black particles, agglomerates of the grayed oxygen-defected TiO(2), were associated with the visible change of the TiO(2).
  
  
  CONCLUSIONS
  It was found that the film-coated tablets were printed utilizing the formation of the black particles by the agglomeration of the grayed oxygen-defected TiO(2) by the UV laser irradiation.
authors.affiliation: Production Technology Department, Eisai Co., Ltd., Kakamigahara, Gifu, Japan. y3-kato@hhc.eisai.co.jp
authors.forename: Yoshiteru
authors.initials: Y
authors.lastname: Kato
authors.forename: Yasuhiko
authors.initials: Y
authors.lastname: Nakashima
authors.forename: Naoki
authors.initials: N
authors.lastname: Shino
authors.forename: Koichi
authors.initials: K
authors.lastname: Sasaki
authors.forename: Akihiro
authors.initials: A
authors.lastname: Hosokawa
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Ishihara
mesh_terms: D002482:Cellulose / Q000031:analogs & derivatives / Q000737:chemistry*; D065347:Hypromellose Derivatives; D007834:Lasers; D008747:Methylcellulose / Q000031:analogs & derivatives* / Q000737:chemistry; D008853:Microscopy; D011108:Polymers; D011327:Printing; D013607:Tablets; D013678:Technology, Pharmaceutical; D013818:Thermogravimetry; D014025:Titanium / Q000737:chemistry*; D014466:Ultraviolet Rays; D014961:X-Ray Diffraction
chemical_list: D011108:Polymers; D013607:Tablets; C009495:titanium dioxide; D065347:Hypromellose Derivatives; D002482:Cellulose; D008747:Methylcellulose; D014025:Titanium