Satintone® Speciality Aluminium Silicate for PVC Wire & Cable Applications

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Calcined Kaolin for PVC wires and cables

Satintone® SP-33 is derived from high-purity hydrous kaolin. It is then calcined to impart excellent insulating properties in PVC compounds. Excellent dispersion in polymeric compounds is ensured by the high level of pulverization applied during processing. Water-washed kaolin feed results in low residue, low soluble salts and consistent quality. Satintone® SP-33 calcined kaolin has been specially designed to be an acid scavenger in medium and high voltage PVC wire insulation compounds. It greatly improves volume resistivity under both wet and dry electrical conditions. Due to its high electrical insulating properties, it is also used in combination with calcium carbonate - in lower-end PVC wire applications.

Volume resistivity test results of Satintone® SP-33 calcined kaolin

Volume resistivity measurements were based on the PVC wire composition shown in Table 1.

Component	Loading (phr)
OxyVinyls® 225F PVC resin	200.0
Palatinol® DPHP plasticizer	87.6
Dibasic lead phthalate	12.0
Dibasic lead stearate	0.4
Satintone-SP33/other fillers tested	40.0

Table 1: PVC wire composition used for subsequent volume resistivity testing.

A comparison of the volume resistivity measurements (Table 2) shows Satintone® SP-33 to be an excellent choice for insulating cables, far outperforming standard and treated calcined kaolins.

Functional Filler	Volume Resistivity (ohms-cm)
Calcium carbonate	10 x 10¹²
Hydrous kaolin	30 x 10¹²
Hydrous treated	50 x 10¹²
Calcined kaolin	50 x 10¹²
Calcined treated	10 x 10¹³
Satintone® SP-33	33 x 10¹³

Table 2: Volume resistivity of PVC compounds when using different functional fillers.

Cost engineering can be carried out by blending the Satintone® SP-33 with calcium carbonate. Table 3 shows how different blend ratios affect volume resistivity. Excellent results can still be achieved, even at high blend rates of calcium carbonate.