The weatherability of PVC building materials is an important performance index. Recently, the weather resistance of PVC materials is related to the two technologies introduced abroad. The brief introduction is as follows:
In the past, in order to improve the weatherability of PVC building materials, ultraviolet absorbents such as benzophenone and benzo-1-zole were added to vinyl chloride lamp resin. But because of UV absorbers. It is difficult for PVC building materials to maintain high weatherability for a long time because UV absorbers are easy to volatilize and deteriorate under the action of light and heat. In addition, deteriorated UV absorbers will damage the transparency of PVC building materials. But in the mixture of vinyl resin, stabilizer, lubricant, processing aid, modifier, plasticizer, filler, antioxidant and ultraviolet absorber
adding nano ceria or using it instead of ultraviolet absorber can greatly improve the weatherability of PVC building materials and keep good mechanical strength and transparency for a long time.
for example, 1.0 phr ceria with particle size of 6nm is added to the mixture composed of 100 phr polyvinyl chloride (degree of polymerization 1030), 3.9 phr organotin stabilizer, 0.5 phr calcium fatty acid, 1.0 phr acrylate, 5 phr methyl propionate butadiene styrene modifier and 0.2 phr polyethylene wax, which is mixed in the mixer, and then mixed in the double roller mill at 180 ℃ for 3 minutes to produce a thickness of 1mm It's a sheet. The composite was preheated at 180 ℃ for 3 hours and pressed at 5MPa for 4 minutes. The thickness of the composite was 2mm. The transparency and hue of the composite were measured by colorimeter and moonlight carbon rod arc irradiation. The results show that the weatherability of nano ceria is improved significantly, and the transparency and hue remain unchanged for a long time.
Using mixed titanium oxide can improve the weatherability and covering power of PVC building materials, prevent color fading, and easy to color, so titanium oxide is widely used in PVC building materials. However, at present, only one of rutile type anatase titanium oxide is added to the mixture based on vinyl chloride resin, which can not fully improve the weatherability.
the test shows that the mixed titanium oxide composed of rutile type and anatase type titanium oxide with the ratio of 1.3:1 can give full play to the role of titanium oxide, further improve the weatherability and hiding power, and prevent fading effect. For example, the hue of PVC specimens containing only 0.54 phr rutile titanium oxide will change after being irradiated by aging testing machine for 200 hours, while the hue of PVC specimens containing 0.54 phr rutile and anatase mixed titanium oxide will remain unchanged after being irradiated by aging testing machine for more than 600 hours. In addition, compared with adding expensive resin and additives to improve weather resistance, the production cost of mixed titanium oxide technology is lower. The above two technologies are simple and feasible, and are suitable for the production of PVC building materials such as pipes, profiles and cover materials.