Regarding the migration of PVC sheet:

Migration only occurs in plasticized PVC products, and when dyes or organic pigments are used, the so-called migration is that partially soluble dyes or organic pigments present in the surrounding solvent penetrate into the surface of PVC products through plasticizers, those Dissolved dye (pigment) particles are also brought to the surface of the product, thus causing bleed, solvent bleed or blooming.

About the weather resistance of PVC sheet:

Refers to the ability of pigments to withstand various climates. These include visible and UV light, moisture, temperature, atmospheric chlorination, and chemicals encountered during product use, important weather resistance including color fastness, chalk resistance, and durability of physical properties.