In recent years, the plastics industry and titanium dioxide can be said to be inseparable from each other. Among the more than 500 titanium dioxide grades in the world, more than 50 are exclusively used for plastics, and the average annual growth rate of up to 6% also makes plastics. Industry has become the fastest growing field in the use of titanium dioxide, and it is the second largest user of titanium dioxide. There are naturally matching indicators where the materials are applied, the parameters are balanced, and the particle size distribution and particle shape are significant. Affecting the key indicators of titanium dioxide for plastics. The size of titanium dioxide for plastics is just within the scope of the laser particle size analyzer. Therefore, for the application of titanium dioxide in the plastics industry, people in the industry may wish to pay more attention.
As we all know, the scientific name of titanium dioxide is titanium dioxide, which has excellent white properties, high hiding power and high achromatic power. It is widely used in inks, paper making, coatings, paints and other industries and enjoys the reputation of 'king of white'. This is exactly titanium. The important reason why white powder is used in plastic products is that titanium dioxide can determine the appearance of light-colored or white plastic products. Of course, titanium dioxide has many other advantages in plastics, such as improving the heat resistance, light resistance, and weather resistance of plastic products. Plastic products are protected from UV light and improve the mechanical and electrical properties of plastic products. Titanium dioxide is used in almost all thermosetting and thermoplastic plastics. They can be mixed with dry resin powders and liquids containing plasticizers. Mixed, the amount is generally about 3-5%, polyolefins (mainly low density polyethylene), polystyrene, ABS, PVC, etc.
In the plastic industry, the quality of titanium dioxide is measured by four major indicators - hiding power, dispersion, weatherability and whiteness. The better the hiding power of titanium dioxide, the thinner and lighter the plastic products produced; the dispersibility affects plastics. Product production costs, the better the dispersion of titanium dioxide, the smoothness and brightness of plastic products will be higher; with good weatherability of titanium dioxide, the outdoor use of plastic products and plastic doors and windows is essential.
The last major indicator is whiteness. The so-called whiteness is the degree from the ideal white. The factors affecting the whiteness of titanium dioxide are mainly the following. The first point is the impurities, in the titanium dioxide process, especially the titanium sulfate Process, most of the work is to remove impurities in the product, because impurities seriously affect the application performance of titanium dioxide, especially whiteness. Color metal oxide impurities can affect the whiteness at very low levels, these elements have Iron, Manganese, Chromium, Copper, etc. These impurities themselves have a color and are easily colored in white titanium dioxide.
The second point is the distribution of particle size and particle size. They mainly reflect the lightness of titanium dioxide particles and reflect light. The smaller the particle size of titanium dioxide, the higher the whiteness value. This is mainly because As the titanium dioxide particle size is smaller, the surface area is increased, light reflection and diffuse reflection are enhanced. According to the characteristics of light waves, when the particle diameter of the pigment particle is smaller than half of the light wave, maximum scattering of the color light at the wavelength can be obtained. The best particle size for the wavelength blue light scattering is about 0.2 μm, and the maximum size for the red light scattering with the longer wavelength is about 0.35 μm. Therefore, the scattered light of the small-size titanium dioxide has a blue phase and the transmitted light This is the blue complementary red and yellow phase. On the other hand, the large particle size titanium dioxide diffuses light in the red phase and the transmitted light is in the blue phase. Usually, the particle size of titanium dioxide for coating is 0.2-0.4 μm, and most plastics use Titanium dioxide particle size is fine, the particle size is 0.15 ~ 0.3μm, because this can get blue bottom phase, for most yellow-phase resin or yellowing resin has shielding effect.
In addition, particle shape, titanium content, and coating agent have a certain influence on the whiteness of titanium dioxide. Among them, the influence of grain shape on whiteness is relatively small. In general, the whiteness of layered titanium dioxide is slightly lower, and the spherical shape and the rod The whiteness of the shape is slightly higher. With the increase of titanium dioxide content, the whiteness value of titanium dioxide is also increased. The content of aluminum, silicon, zirconium and other coating agents is increased, and the whiteness of titanium dioxide is decreased.
It is worth mentioning that, in the production process of plastic masterbatch, the whiteness of titanium dioxide is also an important quality indicator. The plastic masterbatch is a highly concentrated, high-performance color configuration product, that is, the pigment has an extraordinary concentration. It is uniformly distributed in the carrier resin and forms particles of a certain particle size. It is mainly composed of a core layer (pigment), a coupling layer (coupling agent or surfactant), a dispersion layer (lubricant or dispersant), and an increase mixing layer. It is used as a dyeing agent in plastics. It is widely used in the production of blown film, injection molding, hot pressing, injection molding and other plastic products. The color masterbatch has superior coloring effect, is easy to use, saves energy, and has no dust when used. And sewage, so much favored by users. Masterbatch is used as industrial raw materials, performance is usually shown in the follow-up product applications (such as blown film or injection molding), so the performance of titanium dioxide in the color of the grain is also the main Reflected in the application process of masterbatch, titanium dioxide coloring ability, dispersibility, processing performance, whiteness will have a significant impact on the application of masterbatch, logically, and ultimately, the titanium dioxide particle size distribution of the detection.