Formolon S-70 PVC Suspension Resin by Formosa — K71 for Flexible Hose, Film and Cable

Formolon S-70 is a polyvinyl chloride homopolymer manufactured by suspension polymerization. The resin is not a paste resin and is not intended for plastisol work — it is a dry-blend grade for compounding on conventional extrusion and calendering lines. BASTONE supplies the grade under its original Formolon brand; Formosa Plastics manufactures it.

The K-value of 71 (GB/T 5761-2018) and degree of polymerization of 1300 place S-70 in the medium-molecular-weight range that most flexible PVC compounders work with. A chain length at 1300 gives enough mechanical strength and elongation for film, sheet and cable insulation, while keeping melt viscosity low enough that the compound processes on standard calender rolls and extruder screws without excessive shear heating. Converters running a K70-K71 base resin will find S-70 drops into existing recipes without major screw or temperature rework.

High porosity is the property that matters most on the dry-blend line. Porous particles absorb liquid plasticizer into the grain rather than leaving it on the surface, so a 40-80 phr formulation reaches a free-flowing dry blend in a shorter mixer cycle and with less risk of plasticizer bleed in the hopper. Apparent density of 0.50 ± 0.03 g/cm³ (GB/T 20022-2005) reflects the open particle structure and feeds consistently through metering equipment.

Two purity figures carry downstream consequences. Volatiles at max 0.3 % (GB/T 2914-2008) limit moisture-driven bubbles and plate-out during high-output extrusion, which matters for clear film and thin-wall hose where a single void is a reject. Residual VCM at max 1.0 ppm (GB/T 29874-2013) keeps the resin inside the thresholds buyers face for food-contact and medical-adjacent converting, and is the first number most European and Japanese customers ask for. Finished products made from S-70 show high transparency, so the grade suits clear and lightly tinted applications where a hazy base resin would force a formulation change.

BASTONE sources Formolon S-70 through an established supply chain and ships it alongside plasticizers from its own production — DINP, DOTP, DOP, DOA and TOTM — so a buyer can order resin and plasticizer against a single contract and a single shipment.