Formolon PR-640 PVC Paste Resin Copolymer by Formosa Industries — VC/VAc, Low Gelling Temperature

Formolon PR-640 is a dispersion-grade vinyl chloride/vinyl acetate copolymer, not a PVC homopolymer. The vinyl acetate comonomer at 5–6% interrupts the regularity of the PVC chain, lowering the energy needed to fuse the resin into a continuous film. Combined with a degree of polymerization of 1,200 ± 100 and a K-value of 70, the copolymer gels at lower temperatures than a straight homopolymer paste resin of comparable molecular weight.

Lower gelling temperature changes what a coating line can do. A fabric coater running heat-sensitive substrates — polyester scrim, cotton blends, nonwovens — no longer has to push oven temperatures to the point where the carrier shrinks or discolors. Line speed can rise at the same oven setting, or oven setting can drop at the same line speed. Either way the energy cost per square meter falls.

Plastisol viscosity stays in the low-to-medium range. Measured per the TDS recipe of 100 phr resin with 60 phr DINP, Brookfield viscosity reads ≤ 7,000 cps after 2 hours aging at 25°C (No. 6 spindle, 50 rpm), and Severs flow exceeds 400 g/100 sec at 90 psi. A paste that moves freely under pressure fills knife gaps evenly, penetrates carpet backing without starving the fiber bundle, and sprays through underbody coating nozzles without pulsing. The Severs figure matters more than Brookfield for spray and pressure-fed applications, since it describes behavior at high shear rather than at the low shear of a rotating spindle.

Two further properties on the TDS carry weight in finished-part performance. Formolon PR-640 bonds well to fabrics at low temperature, so textile-backed products hold their coating without a separate primer step. Water absorption is low, which protects dimensional stability and electrical behavior in parts that see humidity or washing. Volatiles sit at ≤ 0.40% and apparent density at 0.20–0.30 g/cm³, both consistent with a dispersion resin that disperses cleanly in plasticizer without entrained moisture driving pinholes during fusion.

BASTONE sources Formolon PR-640 through its established supply chain in China and exports it as a traded grade under the Formosa brand. Buyers who need resin and plasticizer in one shipment can take PR-640 together with DINP, DOTP, DOP, DOA, or TOTM from the BASTONE plasticizer range — the TDS test recipe itself calls for DINP, so the pairing is a practical one rather than a cross-sell.