SEMITECH KR-9S — Isopropyl Tri(dioctyl pyrophosphato) Titanate
KR-9S is synthesized from TTIP, 2-ethylhexanol, and pyrophosphoric acid. China supplies over 65% of global TTIP capacity, making pricing sensitive to TiO₂ feedstock cycles and environmental enforcement. Lead times: 3–5 weeks to SE Asia, 6–8 weeks to Europe.
Technical Specifications
| Supply Chain Node | Key Geography | Constraint / Trend | Price Impact |
|---|---|---|---|
| TiO₂ / TiCl₄ feedstock | Yunnan, Shandong (CN) | Chloride-route capacity tight | ↑ Moderate |
| TTIP synthesis | China ≥65% share | Compliance-driven curtailments | ↑ High sensitivity |
| 2-Ethylhexanol | China, South Korea | Propylene oxo margins | ↑ Moderate |
| Pyrophosphoric acid | China, India | Ample capacity | → Stable |
| KR-9S finished product | China, India, Taiwan | Lead time 3–8 wks | ↑ Trending |
| ATH filler (downstream) | SE Asia, Europe | +8% CAGR LSOH cable demand through 2028 | Demand driver ↑ |
Pyrophosphate Chemistry and FR Synergy
KR-9S (CAS 67691-13-8) carries three dioctyl pyrophosphate ligands forming bidentate P–O–Ti bonds with ATH and MgOH surface hydroxyls. The phosphate moieties promote char formation during fire events while ATH/MgOH discharge endothermic water vapor — achieving UL 94 V-0 at 1.6 mm plaques in PE at 55–60 wt% filler.
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Wire and Cable: LSOH Insulation
In XLPE-based LSOH insulation, KR-9S at 0.5–1.2 wt% on filler reduces compound viscosity 25–35% at 60 phr ATH. LOI rises from 28–30% (untreated) to 34–38%. Cable OEMs qualifying to IEC 60332-3 across South Korea and SE Asia specify KR-9S as the preferred coupling agent.
Construction: Waterproofing Membranes and FR Flooring
In ATH/MgOH-filled PE or EVA membranes (50–65 wt% filler), KR-9S at 0.8 wt% reduces die pressure ~20% and eliminates surface mottling. Peel strength on concrete improves 15–20%. EN 13501-1 Class B-s2-d0 validated with KR-9S as sole coupling agent.
Frequently Asked Questions
+Q: How does KR-9S differ from KR-TTS?
A: KR-9S carries pyrophosphate groups that anchor bidentate to ATH/MgOH and act as FR char promoters. KR-TTS uses isostearate ligands for general-purpose non-FR compounds. For halogen-free FR, KR-9S is the correct grade.
+Q: What is the recommended dose for ATH-filled LSOH PE?
A: 0.5–1.2 wt% on total filler weight (not polymer weight). Start at 0.8 wt% and optimize against viscosity and mechanical data. Above 1.5 wt% reduces elongation without further LOI benefit.
+Q: Can KR-9S be used in aqueous systems?
A: No — it hydrolyzes in water, releasing dioctyl phosphate that acidifies the medium. For aqueous filler treatment, use silane coupling agents or hydrolysis-stable zirconates. Add KR-9S to filler before melt compounding.
+Q: What ATH particle size gives best coupling response?
A: D50 5–20 µm, BET 2–18 m²/g. Ultra-fine ATH (BET >18 m²/g) requires higher loading. Coarse ATH (d50 >30 µm) shows diminishing returns due to low surface area.
+Q: How does KR-9S affect smoke density?
A: Moderately reduces smoke density — the phosphate ligands encourage coherent intumescent char that limits volatile escape. Ds(1.5 min) values typically fall 10–20% in ASTM E662 testing. For Class B-s1, supplemental suppressants (zinc borate) may still be needed.
+Q: What are the storage requirements?
A: Sealed PE-lined steel drums, away from moisture and temperatures above 40°C. Shelf life 18 months. Opened drums should be nitrogen-blanketed and consumed within 90 days.
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