Zr(IV) tetra-n-propoxide; clear pale-yellow liquid; bare alkoxide — moisture-sensitive; lowest-cost zirconate.

SZ-TPZ — tetra-n-propyl zirconate, Zr(OC₃H₇)₄ — is the simplest and lowest-cost commercial zirconate coupling agent, formed from zirconium tetrachloride and n-propanol. Molecular formula Zr(OC₃H₇)₄ (anhydrous), molecular weight 327.6 g/mol. Commercial supply is typically as ~70% solution in n-propanol or n-butanol to manage viscosity and provide a stable handling form. SEMITECH supplies SZ-TPZ as a clear pale-yellow to amber liquid at ≥70% active content with ZrO₂ assay 18.5–19.5% (in 70% solution; equivalent to ~26.5% in dry compound), water content ≤0.2% by Karl Fischer.

SZ-TPZ is functionally and structurally equivalent to Kenrich NZ-01 — both are tetra-n-propoxide Zr(IV) compounds with similar performance profile and typical use levels. SEMITECH supply provides the cost-rational sourcing alternative for Asia-Pacific compounders: ex-Zhejiang spot pricing CNY 38,000–45,000/MT (USD 5.3–6.3/kg) vs Kenrich NZ-01 distributor pricing in North America USD 16–20/kg landed — a 40–55% landed-cost discount on equivalent chemistry. The bare alkoxide nature means SZ-TPZ hydrolyses on prolonged moisture exposure (similar to TBT in the catalyst portfolio); storage in sealed steel drums under nitrogen blanket is mandatory beyond 30 days of opening.

Zr alkoxide reacts with surface –OH on filler, releasing n-propanol; deposits Zr-O-filler covalent linkage.

In CaCO₃-filled polyethylene compounds, SZ-TPZ couples by reaction of the four Zr-O-Pr alkoxide bonds with surface –OH and C-OH groups on calcium carbonate particles. Each Zr-O-Pr cleaves on contact with surface hydroxyl, releasing n-propanol vapour and forming a covalent Zr-O-CaCO₃ surface linkage. The remaining alkyl groups on the Zr centre extend into the polymer melt, providing entanglement coupling to the PE chains during compounding. This mechanism is similar to silane coupling on silica, but with two key differences: (1) Zr is more thermally stable than Ti — SZ-TPZ retains coupling activity to 200°C continuous, vs ~220°C for typical titanate; (2) Zr-O-Filler bond is more hydrolysis-resistant than Si-O-Filler from silane, providing better long-term wet-environment performance.

• Loading 0.5–1.0 phr — standard CaCO₃-PE wire & cable insulation; high-loading filler dispersion
• Loading 1.0–1.5 phr — high-loading (60–70%) CaCO₃ masterbatches; mineral structural foam
• Loading 0.3–0.6 phr — fine-particle GCC and PCC fillers in food-contact PE film

SZ-TPZ is dosed during the compounding step — typically as a pre-coated filler (the zirconate is sprayed onto CaCO₃ in a high-speed mixer at 80°C to deposit the Zr-O surface layer before melt compounding) or as in-situ addition during twin-screw extrusion of the masterbatch. Pre-coating gives the most uniform coupling and is preferred for high-loading compounds (>50% filler); in-situ addition is acceptable for low-loading applications (<30% filler) where dispersion is less critical. Typical mechanical-property uplift: tensile strength +15–25%, elongation at break +30–50%, melt-flow index +20–40% (better processability) at the same filler loading vs uncoupled CaCO₃-PE compounds.

CaCO₃-filled PE wire & cable (largest), high-loading mineral masterbatch, structural foam, GCC/PCC compounds.

Calcium-carbonate-filled polyethylene wire and cable insulation is the largest single application — low-voltage (under 1 kV) building wire, telecommunications cable jackets, irrigation drip-line tubing, and industrial multi-conductor cables. SZ-TPZ at 0.5–1.0 phr on filler weight allows CaCO₃ loading to be raised from typical 30% to 50–60% without sacrificing tensile strength or elongation, providing 30–40% raw-material cost reduction in the compound. High-loading CaCO₃ masterbatches for filler-extension of polyolefin, EVA, and polystyrene compounds use SZ-TPZ at 1.0–1.5 phr to allow 60–70% CaCO₃ loading in the masterbatch carrier, providing a let-down ratio of 4–6:1 in downstream compounding.

Mineral-filled structural foam (PE/PP for automotive interior trim, household appliance housings) uses SZ-TPZ at 0.5–1.0 phr to allow CaCO₃ filler at 30–50% loading for cost reduction without sacrificing impact strength. Ground calcium carbonate (GCC) and precipitated calcium carbonate (PCC) compounds in PE film for breathable nappies, shopping bags, and packaging film use SZ-TPZ at 0.3–0.6 phr to improve dispersion and reduce gel formation. Avoid SZ-TPZ for ATH/MDH-filled engineering plastics — for those applications, specify the higher-temperature SZ-12 or SZ-44 phosphato/sulfonyl zirconates which retain activity above 220°C; SZ-TPZ degrades above 200°C and underperforms in high-temperature filled PA, PBT, PPS compounding.

CoA per shipment; 25 kg HDPE; sealed nitrogen blanket; 12-month shelf life; 1-week stocked lead time to Asia.

SEMITECH issues a CoA on every batch with: ZrO₂ assay (gravimetric ignition / XRF, target 18.5–19.5% in 70% solution), active content (titration, target ≥70% Zr-alkoxide in n-propanol), water content (Karl Fischer, target ≤0.2%), APHA colour (target ≤200), density at 20°C, and viscosity at 25°C. Standard packing is 25 kg HDPE jerrycans under dry nitrogen blanket; 200 kg lined steel drums for bulk wire & cable customers. MOQ 25 kg per grade. Lead time 1 week to Asia gateway ports for stocked grade, 4–6 weeks to Europe and North America after sea freight transit.

Storage: bare alkoxide zirconates require nitrogen-blanket sealed storage below 25°C; opened drums should be re-blanketed and consumed within 30 days. Shelf life 12 months sealed. Hydrolysed material shows visible cloudiness and dropped ZrO₂ assay; recover for less critical applications (low-loading masterbatch dispersion) but not for high-precision wire & cable compounds. Cost positioning: SZ-TPZ Q1 2026 ex-Zhejiang spot CNY 38,000–45,000/MT (USD 5.3–6.3/kg); Kenrich NZ-01 distributor pricing North America USD 16–20/kg, Europe USD 18–24/kg landed — 40–55% landed-cost differential favouring SEMITECH for Asia-Pacific compounders. Bulk orders (≥1 t) qualify for SEMITECH’s volume discount programme. Health: SZ-TPZ in solution is mildly skin and eye irritant (n-propanol solvent flash point 23°C; flammable storage class). Handle with nitrile gloves, splash goggles, lab coat; ground all transfer equipment.

SZ-TPZ is the entry-grade workhorse zirconate — Kenrich NZ-01 equivalent at 40–55% landed-cost discount for Asia-Pacific compounders. Standard 0.5–1.5 phr coupling agent for CaCO₃-PE wire & cable, high-loading mineral masterbatch, and structural foam. 200°C thermal stability ceiling — for ATH/MDH-filled engineering plastics specify SZ-12 or SZ-44.

SEMITECH stocked grade; CoA per batch.