Technical Specifications
| Parameter | Specification | Test Method |
|---|---|---|
| Chemical name | Bis(dioctyl pyrophosphato) oxoethylene titanate | — |
| CAS / class | Pyrophosphate ester titanate (monoalkoxy, coordinate) | — |
| Appearance | Amber to yellow clear liquid | Visual |
| Active titanate content | ≥94% | Non-volatile residue |
| Viscosity at 25°C | 150–300 cP | Brookfield LVT |
| Flash point (closed cup) | >65°C | ASTM D93 |
| Density at 25°C | ~1.02–1.05 g/cm³ | Pycnometer |
| Thermal stability | >200°C short term; >180°C continuous | TGA in N₂ |
| Solubility | Miscible with aromatics, ketones, esters | Blend test |
| Recommended loading | 0.5–2.0% on pigment/filler weight | Formulation |
| Shelf life | 12 months / sealed, 5–30°C | Aged sample test |
Coordination Chemistry & Hydrolysis Stability
KR-138S is a monoalkoxy coordinate titanate with two bis(dioctyl pyrophosphato) ligands chelating the titanium center. This six-coordinate geometry resists hydrolysis under ambient humidity — a critical advantage over simple alkoxide titanates that gel on contact with trace moisture in pigment slurries.
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Performance in Solvent-Borne Inks & Industrial Coatings
Reduces grind viscosity 20–40% in solvent-borne flexographic and gravure inks at 1.0–1.5% on pigment weight. On TiO₂-white coatings, 60° gloss improves 4–8 GU. Adhesion to aluminum and steel improves one full cross-cut grade (ASTM D3359) at 0.8–1.2%, surviving 500-hour salt spray.
Dosing & Solvent Compatibility
Fully miscible with aromatics, ketones, and esters. Limited compatibility with aliphatic solvents above 5%. Water content above 1% triggers hydrolysis — add KR-138S to dry resin before pigment, not to pre-dispersed slurry. Pre-dissolve in 5–10% of the solvent fraction, then add to resin before pigment. Store sealed 5–30°C with nitrogen blanket for opened drums.
How KR-138S Compares to Related Grades
Frequently Asked Questions
+Q: What makes KR-138S a 'coordinate' titanate and why does it matter?
A: The intramolecular chelate ring creates six-coordinate geometry that resists hydrolysis in humid pigment slurries. Standard monoalkoxy titanates like KR-9S hydrolyze on contact with trace moisture, losing surface-activity before the pigment is fully coated.
+Q: At what loading rate should KR-138S be used in gravure inks?
A: 1.0–1.5% on pigment weight. This reduces mill-base viscosity 20–35%. Above 2.0% over-lubricates the pigment surface, reducing ink tack and impairing dot transfer.
+Q: Can KR-138S be used in waterborne or UV-curable systems?
A: Not suitable for waterborne — titanate esters hydrolyze above 1% water content. For UV-curable 100% acrylate, KR-138S can be used at 0.3–0.8% as dispersant, but decomposition above 220°C limits use in UV-powder coatings.
+Q: How does KR-138S differ from KR-138D?
A: KR-138D carries a different monoalkoxy ligand optimized for mineral-oil and high-shear environments (PVC plastisols, rubber). KR-138S is formulated for solvent-borne systems.
+Q: What is the correct addition sequence in a high-solids primer?
A: Pre-dissolve in 5–10% of the solvent fraction, blend into resin before any pigment. Adding to a finished grind delivers only 30–50% of expected adhesion benefit.
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