Zinc Hydroxystannate

Catalog	ACM12027962-2
CAS	12027-96-2
Structure
Description	Zinc Hydroxystannate and Zinc Stannate are active smoke suppressants as well as flameretardants. Their superior performance is because of their dual phase mechanism. In addition to exhibiting vapor phase action, similar to Antimony Trioxide, they also exhibit condensed phase action during which they act as excellent char promoters. The condensed phase action of Zinc Hydroxystannate and Zinc Stannate enhances the formation of a thermally stable carbonaceous layer at the expense of aromatic, volatile and flammable products. These products exhibit synergy with Zinc Borate, Ammonium Octamolybdate and Antimony Trioxide.
Synonyms	ZHS / ZnSn(OH)6
Molecular Formula	ZnO.SnO3H2O
Appearance	White powder
Application	Zinc Hydroxystannate and Zinc Stannate are effective in halogen free and halogen containing systems. Although generally, there is little difference in the effectiveness of Zinc Hydroxystannate and Zinc Stannate, the latter is the preferred additive for polymers that are processed at temperatures above 200oC.
Bulk Density	0.6 gm/cm³
Content	Tin 41.5 - 43 % Zinc 22 - 24 %
Decomposition Temperature	200 °C
Loss On Ignition	17 - 19 %
Moisture Content	0.005
Particle Size	10 µm (D90); Median Particle Size, 1 µm(D50)
pH	10 (5% aqueous slurry)
RefractiveIndex	1.9
Specific Gravity	3.3
Specific Surface Area	7 cm²/gm

Case Study

Comparison of the Performance of Zinc Hydroxystannate and Antimony Trioxide for Flame Retardant PANVDC Fibers

Kim, Ji Su, et al. Polymers, 2020, 12(11), 2442.

Although antimony trioxide (ATO, Sb2O3) is one of the most common flame retardants used in modified acrylic fibers, it is suspected to be carcinogenic to humans. In order to evaluate the feasibility of non-toxic zinc hydroxystannate (ZHS) as an alternative to ATO, this study compared the effects of ZHS, ATO and their combination in the preparation of flame retardant poly(acrylonitrile-co-vinylidene chloride) (PANVDC) fibers.
Comparison of flame retardant mechanism and modification effect
· The flame retardant mechanism for the PANVDC-ATO fiber primarily involved the ATO component, which functioned through a halogen unit in the gas phase. In contrast, the PANVDC-ZHS fiber's flame retardancy came from the reaction of ZHS with the halogen and subsequently with the AN unit, promoting cyclization and carbonization. This process resulted in a char structure that was more robust and stable against heat and oxidation compared to the char layers produced by both the PANVDC fiber and the fiber containing ATO.
· When comparing flame retardancy, PANVDC-ZHS exhibited the highest LOI value among the PANVDC films. Additionally, based on the results of the MCC, the peak heat release rates (PHRR) for the PANVDC-ATO/ZHS and PANVDC-ZHS fibers were significantly lower than those for the PANVDC and PANVDC-ATO fibers. The rapid formation of a stable char layer in PANVDC with the addition of ZHS significantly enhanced its flame retardant properties. Consequently, ZHS is determined to be a more effective flame retardant for PANVDC compared to ATO.

Zinc Hydroxystannate/Intumescent Flame Retardant System For Polypropylene

Su, Xinqing, et al. Polymer degradation and stability, 2012, 97(11), 2128-2135.

Polypropylene (PP) composites combining the synergistic effects of zinc hydroxystannate (ZHS) and intumescent flame retardant additives (IFR) were prepared. The experimental results show that the PP/IFR/ZHS samples meet the UL-94 V0 rating and maximum LOI value of 32 in the case of 1 wt% ZHS and 24 wt% IFR.
Preparation of PP/IFR/ZHS composites: All flame-retardant PP composites were prepared using a CM reciprocating single-screw extruder (CM-30) according to specific ingredient ratios. The temperature range of the single-screw extruder was set at 160-200°C. The resulting compounds were subsequently dried in an oven and further injection molded into rods using an injection molding machine for fire performance characterization.
Flame retardant mechanism: ZHS combined with the IFR system based on ammonium polyphosphate (APP) and pentaerythritol (PER) showed a significant synergistic effect on the flame retardant properties of PP. The addition of ZHS to PP/IFR not only increased the carbon residue but also formed a folded carbon structure. This morphology can effectively act as a barrier to heat and oxygen, thereby improving the flame retardant properties of the intumescent flame-retardant PP samples.

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