1. Opacity.
The opacity of plastic products mainly depends on the total amount of titanium dioxide in the product, so the thickness of the product is also an important factor.
(1) The opacity of titanium dioxide increases rapidly with the decrease in the content of titanium dioxide, and the amount of additional required to reach the equilibrium value is large.
(2) The influence of titanium dioxide on the opacity of plastic products is also related to the amount of addition, that is, also related to the thickness of the product. The opacity is also related to the thickness of the film and the titanium dioxide content. The higher the titanium dioxide content, the thicker the film thickness, the greater the opacity.
(3) The opacity is also related to the degree of aggregation of titanium dioxide. The greater the degree of aggregation, the smaller the opacity.
(4) How to increase opacity? At present, there are often thin products and soft sunshade curtains, etc., and it is hoped that the opacity is highly opaque. It is impossible to add only titanium dioxide. Usually, a small amount of carbon black of 0.02% or ultrafine aluminum powder of 0.05% can be added. In addition, the addition of color pigments can also increase the opacity of the article.
2. Splitting
The main problem with the coated film is that the film is broken. The main reason is that the low-molecular-weight polyethylene is not good in quality, the volatile matter causes the film to break, and some is caused by the volatile component in the titanium dioxide coating.
3. Whitening of titanium dioxide
In the production of white masterbatch, fluorescent whitening agent or ultramarine blue is often added to increase the whiteness. This is because the reflectivity of titanium dioxide to incident light is not 100%, especially for the blue and violet spectral bands. Therefore, it is not pure white, twenty has a pale yellow hue, and the color light complementary to the blue color and the yellow color light is mixed to obtain white. The fluorescent whitening agent can absorb ultraviolet light (wavelength 300~400nm) and then emit blue-violet fluorescence (wavelength 420~480nm), so it can significantly improve whiteness and gloss. However, the fluorescent whitening agent is different from the whitening mechanism. The former is “adding light” and the latter is “dimming”. When the addition of light is strong, the reflectivity can be greatly exceeded by 100%. Since it is believed that the object that can reflect 100% of the incident light should be the whitest, after the introduction of fluorescent whitening, people get whiter than white. In terms of people’s visual perception, the blue color is whiter than the white color with yellow color.
4. Aging of white film
PE products containing different grades of titanium dioxide has less quality loss of PE products containing high durability titanium dioxide under the same exposure time. A PE product containing titanium dioxide added with a UV stabilizer has a long embrittlement time.