Description

Di-n-Octadecyl Phosphite is a high-molecular-weight organophosphorus compound primarily utilized as a highly effective secondary antioxidant and processing stabilizer. Its core value lies in its ability to decompose hydroperoxides, thereby preventing the oxidative degradation of polymers and enhancing their long-term thermal stability. This makes it a critical additive for manufacturers in the plastics, synthetic fiber, and lubricant industries seeking to improve product durability and performance under demanding conditions.

Application

• As a secondary antioxidant (hydroperoxide decomposer) in polyolefins (PP, PE) and other polymers to synergize with primary phenolic antioxidants.
• As a processing stabilizer for plastics during high-temperature extrusion and molding, preventing melt flow instability and discoloration.
• As a stabilizer component in synthetic lubricants and greases to inhibit oxidation and viscosity increase.
• As an additive in adhesives and sealants to improve thermal aging resistance.
• In the stabilization of synthetic fibers like polypropylene against UV and thermal degradation.
• As a co-stabilizer in PVC formulations, often used in combination with metal soaps.
• In the production of specialty chemicals as an intermediate for further phosphite ester synthesis.

Basic Information

Item	Detail
Product Name	Di-n-Octadecyl Phosphite
CAS No.	19047-85-9
Molecular Formula	C₃₆H₇₅O₃P
Molecular Weight	586.96 g/mol
Synonyms	Distearyl Phosphite; Dioctadecyl Phosphite; Dioctadecyl hydrogen phosphite; Phosphorous acid, dioctadecyl ester; Bis(octadecyl) phosphite; Distearyl hydrogen phosphite; Antioxidant DSTP; Hostanox PAR 24
EINECS	242-798-5

Quality Control

Our Di-n-Octadecyl Phosphite is manufactured under a stringent quality management system. Every batch undergoes comprehensive analytical testing to ensure it meets precise specifications for purity, color, and acid value. A Certificate of Analysis (COA) detailing these results is provided with each shipment to guarantee traceability and compliance with your quality requirements.

Storage

Preserve in a tightly closed container, protected from light. Store in a cool, dry, well-ventilated area at room temperature (15-25°C). This material is hygroscopic (moisture-sensitive) and easily oxidized; therefore, containers should be kept tightly sealed under an inert atmosphere (e.g., nitrogen) after opening to prevent moisture absorption and degradation.

Specification

Item	Specification
Appearance	White to off-white flake or powder
Identification (IR)	Conforms
Assay (Titration)	≥ 95.0 %
Acid Value	≤ 1.0 mg KOH/g
Melting Point	60 - 70 °C
Phosphorus Content	5.0 - 5.5 %
Color (APHA)	≤ 50
Moisture (KF)	≤ 0.5 %

Note: Specifications can be tailored. Please contact us for the detailed technical data sheet of a specific grade.