| 摘要 |
<p>A photobleach process requiring a combination of three components in order to effect a superior rapid bleach. The components are radiation, oxidant and an appropriate aqueous medium. When all three components are present within specified limits, the bleach is more rapid than conventional processes and in an optimum form of application will achieve whiteness superior to any other process no matter how vigorously applied. Specifications of the three essential components are: (1) Radiation Source: the preferred and optimum light source for the present invention should contain a high proportion of blue wavelengths. However, if the bleaching time is sufficiently short, wide spectrum light sources can be employed if there are advantages of availability or physical form. The rate or photobleaching increases with light intensity. (2) Oxidant: hydrogen peroxide is the oxidant of most practical importance. The concentration of peroxide recommended is approximately 2.5 % (w/v) as H2O2, but between 1 % and 10 % w/v can be viable depending on how the process is carried out. (3) Aqueous medium: the range of interest for the current invention is pH 9.0 - 11.5. The optimum is approximately pH 10.5 ± 0.5, and in this range the common alkaline buffers are only weakly effective. Tri-sodium phosphate has proven in experiments to be reasonably satisfactory.</p> |
