Use of Uncoated CaCO₃ (Oman, 1000 Mesh) in PVC Pipe
Overview:
Uncoated calcium carbonate (1000 mesh) from Oman provides fine particle size for smooth extrusion and stiffness improvement. Its lower whiteness versus premium Vietnam grades makes it ideal for non-white coloured PVC pipes. For white pipes, compensate with additional TiO₂.
Best-fit applications
Grey, black, blue, orange, green pipes (pressure & non-pressure)
Conduit, casing, SWR, agriculture pipes where base colour masks filler undertone
Benefits in PVC compounding
Cost optimization: partial PVC resin replacement without loss of rigidity
Stiffness & dimensional stability: improved ring stiffness, reduced shrinkage/warpage
Processing: fine particles aid melt flow, stable extrusion, smoother surface
Pigment base: neutral enough for medium/dark colours; consistent shade control
When using in white pipes
Increase TiO₂ to maintain L* / brightness.
Typical adjustment guide: add +0.2–0.5% TiO₂ for each 1-point drop in whiteness index (internal trial to confirm).
Keep plate-out low with proper external lubricants (PE wax/ester wax).
Practical guidelines
Loading level (rigid PVC pipe): 8–20 phr (≈6–15% by weight), adjust per stiffness/impact targets.
QC to watch: brightness/whiteness (L*, b*), moisture ≤0.3%, CaCO₃ ≥96%, residue on 325 mesh minimal.
Dispersion: add early in high-shear zone; ensure stabilizer system (Ca-Zn/lead-free) is adequate.
Colour strategy: use Oman CaCO₃ predominantly in non-white bases; for whites/pastels keep usage lower or blend with higher-whiteness CaCO₃.