Titanium Dioxide in various types of ink manufacturing, the consumption ratio is relatively large, between 25% - 50%, some even larger. Therefore, titanium dioxide plays an important role in the quality of ink.
The influence on the whiteness of ink
The influence of impurities in titanium dioxide on ink whiteness. Generally speaking, if trace amounts of iron, chromium, cobalt, copper and other impurities are mixed into titanium dioxide, the prepared ink will produce color deviation and reduce whiteness. This is due to the impurity ions in titanium dioxide, especially metal ions, which distort the crystal structure of titanium dioxide and lose its symmetry. Rutile titanium dioxide is more sensitive to impurities. For example, when the content of Iron Oxide in rutile titanium dioxide is more than 0.003%, it will show color, and when the content of iron oxide in anatase titanium dioxide is more than 0.009%, it will produce color reaction. Therefore, it is very important to select fine and impurity free titanium dioxide.
The influence of the shape, size and distribution of titanium dioxide particles on the whiteness was studied. High quality titanium dioxide particles have smooth shape and no edges and corners. If using titanium dioxide particles with edges and corners on the surface of particles, it will greatly weaken the reflection of light and reduce the whiteness of ink. The size of titanium dioxide particles should be controlled in the range of 0.2-0.4 μ m, which is equivalent to about 1 / 2 of the wavelength of visible light, in order to obtain high scattering ability and make its color appear whiter. When the particle size is less than 0.1 μ m, the crystal is transparent. If the particle size is more than 0.5 μ m, the light scattering ability of pigment will be reduced and the whiteness of ink will be affected. For this reason, the particle size of titanium dioxide should be appropriate and evenly distributed to show good whiteness.
The influence on the covering power of ink
The refractive index of titanium dioxide crystal itself will directly affect the ink covering force. Generally, the refractive index of titanium dioxide is the best in white pigment. When preparing white ink, titanium dioxide with high refractive index should be selected to enhance the covering power of white ink.
The influence of particle size, particle structure and dispersion of titanium dioxide on the covering power of white ink was studied. In general, the smaller the particle size is, the smoother the particle surface is, the better the dispersion of titanium dioxide in the Resin binder is, and the stronger the covering power is. Because of the obvious crystal structure of titanium dioxide, the refractive index of titanium dioxide is larger than that of color developing agent, and the larger the refractive index difference, the stronger the covering power of titanium dioxide. Practice has proved that rutile titanium dioxide has better covering power than anatase titanium dioxide, so it is more widely used in ink manufacturing.
The influence on the coloring power of ink the coloring power of titanium dioxide depends on the scattering ability of titanium dioxide to visible light, and it has a direct influence on the coloring power of ink. The larger the scattering coefficient is, the stronger the coloring power is; the higher the refractive index of titanium dioxide is, the stronger the coloring power is. Titanium dioxide has the highest refractive index in white pigments, and the refractive index of rutile titanium dioxide is higher than that of anatase titanium dioxide. Therefore, titanium dioxide with strong scattering ability and high refractive index should be selected.
The influence on Dispersibility
The shape of titanium dioxide particles and the uniformity of light reflection directly affect the dispersibility of titanium dioxide. If the surface of titanium dioxide particles is smooth and the reflection is uniform, the dispersion is good, and the gloss and whiteness of the prepared white ink are also good; on the contrary, if the surface of the particles is rough and the diffuse reflection is increased, the gloss will be greatly reduced, and the dispersion is poor, which directly affects the whiteness and transfer performance of the white ink. Therefore, titanium dioxide must be treated before it can be used.
To sum up, with the rapid development of packaging and publishing printing industry at home and abroad, the market demand for ink will increase day by day. As a very important white pigment in ink, titanium dioxide has many properties and functions that can not be replaced by any other materials. Therefore, the use of titanium dioxide in ink will increase year by year, and the market application prospect will be very broad.
