Hosokawa Akihiro, Kato Yoshiteru, Terada Katsuhide
Manufacturing Department Misato Plant, Eisai Co., Ltd. , Misato, Kodama, Saitama , Japan .
Drug Dev Ind Pharm. 2014 Aug;40(8):1047-53. doi: 10.3109/03639045.2013.807276. Epub 2013 Jun 20.
The purpose of this study was to examine the application of ultraviolet (UV) laser irradiation to printing hard gelatin capsule shells containing titanium dioxide (TiO2) and to clarify how the color strength of the printing by the laser could be controlled by the power of the irradiated laser. Hard gelatin capsule shells containing 3.5% TiO2 were used in this study. The capsules were irradiated with pulsed UV laser at a wavelength of 355 nm. The color strength of the printed capsule was determined by a spectrophotometer as total color difference (dE). The capsules could be printed gray by the UV laser. The formation of many black particles which were agglomerates of oxygen-defected TiO2 was associated with the printing. In the relationship between laser peak power of a pulse and dE, there were two inflection points. The lower point was the minimal laser peak power to form the black particles and was constant regardless of the dosage forms, for example film-coated tablets, soft gelatin capsules and hard gelatin capsules. The upper point was the minimal laser peak power to form micro-bubbles in the shells and was variable with the formulation. From the lower point to the upper point, the capsules were printed gray and the dE of the printing increased linearly with the laser peak power. Hard gelatin capsule shells containing TiO2 could be printed gray using the UV laser printing technique. The color strength of the printing could be controlled by regulating the laser energy between the two inflection points.
本研究的目的是考察紫外（UV）激光辐照在含二氧化钛（TiO₂）的硬明胶胶囊壳印刷中的应用，并阐明激光印刷的颜色强度如何通过辐照激光的功率来控制。本研究使用了含3.5% TiO₂的硬明胶胶囊壳。胶囊用波长为355 nm的脉冲紫外激光辐照。印刷胶囊的颜色强度用分光光度计测定为总色差（dE）。胶囊可用紫外激光印成灰色。印刷过程伴随着许多黑色颗粒的形成，这些黑色颗粒是缺氧TiO₂的团聚体。在脉冲激光峰值功率与dE的关系中，有两个拐点。较低的点是形成黑色颗粒的最小激光峰值功率，且与剂型（如薄膜包衣片、软胶囊和硬胶囊）无关，保持恒定。较高的点是在壳中形成微气泡的最小激光峰值功率，且随配方而变化。从较低的点到较高的点，胶囊被印成灰色，印刷的dE随激光峰值功率线性增加。含TiO₂的硬明胶胶囊壳可用紫外激光印刷技术印成灰色。通过在两个拐点之间调节激光能量，可以控制印刷的颜色强度。
