In the production and use of PVC-U profiles, sometimes the problem of discoloration of the extruded PVCu window and door profile surface is often encountered.  It affects production and product quality. H.D.Plastics has gained extensive experience in processing and formulating PVC-U profiles or extruded channels for more than10 years, we will comprehensively analyze the reasons for the surface discoloration of PVC-U profiles.

With normal surface quality, the PVC-U profile is generally white, and the surface is smooth and glossy. According to the requirements of GB8814-88, the profile “should not have defects such as scratches, bumps, cracks, impurities, etc.”, “the color of the profile should be uniform and consistent.”

The causes of discoloration of PVC-U furniture profiles for window and door.

  1. The discoloration of PVC-U profiles is the result of a combination of internal and external factors. The external conditions include ultraviolet radiation, a certain temperature, humidity and oxygen conditions, air pollution (dust sulfur, acid rain, etc.). Dry and hot climatic conditions can accelerate the degradation of PVC-U. The internal factor is that the PVC resin degrades and decolorizes HCl under light and oxygen. Therefore, controlling the quality of PVC resins, especially the degradation of PVC resins and the formation of polyene structures, is the primary problem to solve the discoloration of profiles.
  2. In addition, various additives in the production formula of PVCu profiles, including stabilizers, antioxidant systems, titanium dioxide, pigments, and fillers, due to the differences in their respective quality, also have discoloration factors. By optimizing the stable system in the formula and simultaneously matching the necessary weathering specifications rutile titanium dioxide, controlling the quality of the resin and various additives in the formula and its own possible discoloration factors is a necessary condition to reduce the discoloration of the profile.
  3. Also, factors that cause discoloration of the profile in the production process and equipment molds should also be considered. The main purpose is to reduce the thermal and oxygen degradation of PVC under thermal processing and mechanical shearing conditions, and ensure that the profile has better stability under the conditions of light, oxygen and weather aging. This includes the control of thermal oxygen degradation by various processes such as compounding, extrusion, plasticizing, shaping, and cooling.

How to solve this problem?

  • (1) Adjust the formula, adopt a scientific and advanced formula system and a non-toxic and efficient thermal stabilization system to improve the comprehensive stability of the formula against heat, light, and oxygen;
  • (2) Establish a raw material laboratory to increase the cause of discoloration of the profile surface Analysis ability and quick judgment ability;
  • (3)establish a reliable and stable raw material supply channel to ensure the quality of raw materials;
  • (4)appropriately increase the number of heat stabilizers, light stabilizers, and antioxidants, and handle raw materials in a timely manner The discoloration of the surface of the profile caused by the change;
  • (5) When packaging, storing, and transporting PVC-U profiles, the requirements of GB8814 should be strictly followed.
extruded PVCu window and door profile

extruded PVCu window and door profile

H.D.Plastics is a leading manufacturer for extruding PVC-u window and door profiles, also other thermal plastic profiles, and extruded tubing by customization.  please go back to our home page www.coextrudedplastics.com for more information.