Opaque white pigmented poly:alkylene terephthalate compsn. - with high reflectivity, esp. for reflectors

摘要

The compsn. consists of (a) 96.5-50 wt.% of a polyalkylene terephthalate, (b) 3.5-50 wt.% of an inorganic white pigment, and (c) 0.01-1 wt.% of >=1 stabiliser. Polyethylene terephthalate with intrinsic viscosity 0.5-1 dl/g (as 0.5 wt.% soln. in 1:1 phenol/tetrachloroethane), polypropylene terephthalate, and polybutylene terephthalate with intrinsic viscosity 0.7-1.4 dl/g (as 0.5% soln. in 1:1 phenol/1,2-dichlorobenzene) are esp. suitable. Copolymers can be used. White pigments include ZnS, ZnO, Mg or Ca titanate, Ti phosphate, and esp. TiO2 prepd. from TiCl4. The use of the compsn. for the prodn. of reflectors is claimed. Other uses include building stones esp. for outdoor cinemas, light emitting diodes, searchlight reflectors, reflectors for vehicle rear lights, esp. fog lights, or for traffic lights, and vehicle winkers. The compsn. has high melt stability; redn. in intrinsic viscosity during compounding at 240-260 degrees C for 1-2 mins. is 5%. It has high light reflection (>90%) and good optical density. Large amts. of white pigments can be incorporated with on only a small redn. in impact strength. Increasing pigment content gives appreciable rise in hardness, flexing strength and elasticity.