When we use PVC rigid board, we will be curious about its color, because the use of different colors will collide with different visual sensations, but some users will find that after using the board for a period of time, the color will become a bit hairy Huang, let us be confused, then we come to understand the mystery here, and look forward to your attention.
一 、 Discoloration of profile
The main manifestations of discoloration due to heat, oxygen, and light aging are yellowing of profiles, and the following situations occur during production:
1. When processing the profile, it is found that the color is not uniform.
2, the profile is significantly yellowed after heating deformation.
3. After heating, it is in good condition, but it will become gray when the profile is made for a short time. The profile does not turn yellow during normal production, but turns yellow during subsequent window-forming products.
2. Discoloration of lead and sulfur pollution
1. After the PVC hard board is exposed to rain and strong sunlight outdoors, part of the surface of the profile discolors, and some of the profiles on the same window are more discolored in the place of the remaining raindrops, and the surface color is light gray or light gray. "
2. Among other reasons, the uneven dispersion of ultramarine as a light cyan colorant is one of the reasons. Ultramarine-a sulfur-containing compound of aluminum silicate.
3. Alkali-resistant and acid-resistant. If it is used too much or accumulates in large quantities, in theory, it may generate black lead sulfide when it interacts with sulfur-containing compounds. The phenomenon of discoloration has appeared in many profile door and window factories.
3, the relationship between molecular structure and color
1. Under the effect of heat and light, there are a certain number of low-molecular-weight and low-molecular components, which reduces the thermal stability of the polymer.
2. When the PVC hard board is exposed to the natural environment, once the hydrogen chloride is desorbed, the original calcium carbonate component will be converted into a new component of calcium chloride, which is dispersed in the oxidative degradation product layer and forms a potential water-absorbing position. One of the reasons for the yellowing of outdoor profiles.
3. In addition to temperature and stress, plastics are subject to thermal stress during the process of high agitation, cold agitation, extrusion, etc. during molding under the influence of shear stress and tensile stress.
In summary, the yellowing of the PVC rigid board may be a problem in the molding process during production, or it may be that we put it in a cool and humid place during storage, which reduces its performance, so this We need to pay attention to the surrounding environment when storing the board to avoid being corrosive. At the same time, we recommend that you choose a regular manufacturer when you buy this product.