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Iso-Decyl Diphenyl Phosphate is a liquid phosphate triester used primarily as a combined plasticizer and flame-retardant additive.
It provides flexible PVC and other compatible polymers with low-temperature flexibility, low volatility, processing fluidity, and a non-halogenated source of phosphorus.
Its low pour point, high flash point, and pumpable liquid form are advantageous in industrial compounding and coating operations.
CHEMICAL IDENTITY AND COMMON NAMES
Iso-Decyl Diphenyl Phosphate is a monoalkyl diaryl phosphate ester containing two phenoxy groups and one branched C10 isodecyl group.
The commercial substance is produced from branched isodecyl alcohol and can contain closely related constitutional isomers with the same molecular formula and functional characteristics.
The name 8-methylnonyl diphenyl phosphate describes a representative branched C10 structure associated with the substance.
Iso-Decyl Diphenyl Phosphate is distinct from triphenyl phosphate, which contains three phenyl groups, and diisodecyl phenyl phosphate, which contains two isodecyl groups.
Small quantities of these related phosphate esters can occur in the commercial product, making phosphate-ester distribution an important grade-selection parameter.
Synonyms and Common Names: Isodecyl diphenyl phosphate, diphenyl isodecyl phosphate, isodecyl diphenylphosphate, isodecyl diphenyl phosphate ester, diphenyl isodecyl phosphate ester, phosphoric acid isodecyl diphenyl ester, phosphoric acid diphenyl isodecyl ester, 8-methylnonyl diphenyl phosphate, phosphoric acid (8-methylnonyl) diphenyl ester, isodecyl alcohol diphenyl phosphate, IDDP, IDDPP
TECHNICAL IDENTIFICATION
CAS Number: 29761-21-5
EC / EINECS Number: 249-828-6
Molecular Formula: C22H31O4P
Molar Mass: 390.45 g/mol
Representative IUPAC Name: 8-Methylnonyl diphenyl phosphate
Chemical Class: Alkyl diaryl phosphate triester
Functional Type: Non-halogenated plasticizer and flame-retardant additive
Common Abbreviation: IDDP
Theoretical Phosphorus Content: Approximately 7.93%
PHYSICAL AND CHEMICAL PROPERTIES
Appearance: Clear, colourless to pale-yellow oily liquid
Physical State: Liquid
Odour: Mild characteristic odour
Density: 1.07–1.09 g/cm³ at 20 °C
Kinematic Viscosity: Approximately 21.9 mm²/s at 25 °C
Refractive Index: Approximately 1.505 at 25 °C
Pour Point: Below -50 °C
Flash Point: Approximately 240 °C, open cup
Fire Point: Approximately 260 °C
Vapour Pressure: Approximately 3.6 × 10^-5 Pa at 20 °C
Water Solubility: Approximately 0.011 mg/L at room temperature
Partition Coefficient: log Kow = 6.11 at 25 °C
Surface Tension: Approximately 34.3 mN/m at 20 °C
Reduced-Pressure Boiling Behaviour: Approximately 245 °C at 1.33 kPa, with decomposition
Volatility: Very low at ambient temperature
Solubility in Organic Media: Soluble in many organic liquids and compatible with numerous hydrophobic polymer systems
Acid-Base Behaviour: Neutral phosphate ester without a relevant aqueous pKa
FUNCTIONAL CHARACTERISTICS
The branched isodecyl group increases molecular flexibility and produces a substantially lower pour point than more highly arylated phosphate plasticizers.
This structure supports flexibility at low service temperatures and keeps the product fluid during storage, pumping, and metering.
The two phenyl groups and central phosphate group provide thermal character and contribute to flame suppression.
Depending on the polymer matrix, phosphorus can promote protective char formation and interfere with combustion reactions.
The product generally provides slightly less flame-retardant efficiency than highly arylated phosphate esters, while offering improved low-temperature plasticization and favourable smoke performance in properly balanced flexible-PVC compounds.
Very low vapour pressure reduces evaporative loss during normal processing and service.
The high flash point facilitates handling in high-temperature polymer and coating operations, although the liquid remains combustible when strongly heated.
Its hydrophobic character supports compatibility with organic binders but prevents direct dilution in water without an appropriate emulsification or dispersion system.
PRODUCTION AND COMMERCIAL FORM
Industrial production can proceed through esterification of a phosphoryl chloride intermediate with phenol or phenoxide and branched isodecyl alcohol.
Another established route uses catalytic transesterification of a triaryl phosphate with isodecanol.
Neutralization, washing, vacuum removal of residual volatile materials, and filtration produce the finished clear liquid.
Reaction stoichiometry and purification control the proportions of Iso-Decyl Diphenyl Phosphate, triphenyl phosphate, diisodecyl phenyl phosphate, residual isodecyl alcohol, free phenol, moisture, and acidic components.
The commercial product is normally supplied as a neat technical-grade liquid.
Its low pour point and moderate viscosity allow direct pumping, metering, and incorporation without melting.
APPLICATIONS AND INDUSTRIES
Flexible PVC compounds
Flexible PVC is the principal application for Iso-Decyl Diphenyl Phosphate.
It functions as a plasticizer while adding phosphorus-based flame-retardant performance.
The product can reduce compound hardness, increase flexibility and elongation, and improve performance at low temperatures.
It is commonly balanced with general-purpose plasticizers, stabilizers, fillers, and supplementary flame retardants.
The selected concentration influences hardness, tensile properties, volatility, extraction resistance, flame behaviour, and smoke generation.
Wire, cable and electrical insulation
Iso-Decyl Diphenyl Phosphate is used in flame-retarded PVC insulation, cable jacketing, connectors, and related electrical components.
Its low pour point supports flexibility in cold environments, while its low volatility assists retention during heat ageing.
Electrical compounds are evaluated for volume resistivity, dielectric behaviour, heat ageing, migration, smoke generation, and flame performance.
Low acidity, controlled moisture, and consistent phosphate-ester composition are particularly important for this application.
Automotive and interior vinyl
The product is used in flexible automotive vinyl, interior trim, upholstery, barrier materials, and selected vinyl foam systems.
It combines plasticization with a phosphorus contribution to fire performance without introducing halogens into the additive molecule.
Low-temperature flexibility is useful for components exposed to seasonal temperature changes.
Colour, odour, fogging, volatility, migration, and heat-ageing performance are important selection criteria for interior applications.
Construction and industrial vinyl
Applications include coated fabrics, flexible sheeting, moisture barriers, pipe-insulation components, flame-retarded vinyl foam, and mining conveyor-belt compounds.
The additive helps maintain flexibility while contributing to the flame response required in industrial and construction environments.
Formulation design considers mechanical strength, abrasion resistance, extraction, smoke generation, and compatibility with other flame-retardant components.
Low-volatility grades are useful where products experience prolonged service at elevated temperatures.
Polyurethane and synthetic rubber
Iso-Decyl Diphenyl Phosphate can serve as a plasticizing and flame-retarding additive in compatible polyurethane and synthetic-rubber formulations.
Its liquid form facilitates incorporation into elastomer, coating, and polymer-processing systems.
Low moisture and low acid value are important in polyurethane systems because water and acidic contaminants can interfere with isocyanate chemistry and catalyst balance.
Compatibility, cure response, mechanical properties, migration, and flame performance are evaluated in the complete formulation.
Textile coatings, paints and pigment dispersions
The product is used in selected textile coatings and organic coating systems as a low-volatility plasticizing component with supplementary flame-retardant functionality.
It can improve film flexibility and reduce brittleness in compatible binder systems.
Iso-Decyl Diphenyl Phosphate also functions as an organic liquid component in pigment dispersions.
Its viscosity, surface tension, solvency behaviour, colour, and compatibility influence pigment wetting, dispersion stability, and finished-film properties.
Waterborne systems require suitable emulsification or dispersion technology because the phosphate ester has extremely low water solubility.
Cellulosic resins and specialty plastics
The phosphate ester is compatible with several cellulosic and specialty resin systems, including cellulose nitrate, cellulose acetate butyrate, ethyl cellulose, polymethyl methacrylate, and polystyrene.
It can provide plasticization, processing assistance, and phosphorus-based flame-retardant contribution.
Resin compatibility, optical clarity, colour, mechanical properties, migration, and extraction resistance determine the appropriate addition level.
Low colour and low free-phenol content are especially relevant in clear or lightly coloured products.
Lubricants and specialty fluids
Iso-Decyl Diphenyl Phosphate is used as a phosphorus-containing functional additive in selected industrial lubricant and non-aqueous specialty-fluid formulations.
Its high flash point, low volatility, liquid form, and phosphate ester chemistry support use in thermally demanding systems.
Selection depends on compatibility with the base fluid, elastomers, seals, metals, and other additives.
Viscosity, acidity, hydrolytic stability, and low-temperature flow are central evaluation parameters.
GRADE SELECTION AND PRODUCT SUITABILITY
Commercial grades are differentiated primarily by Iso-Decyl Diphenyl Phosphate content and overall phosphate-ester distribution.
Gas chromatography is commonly used to measure the principal component, triphenyl phosphate, diisodecyl phenyl phosphate, residual isodecyl alcohol, and free phenol.
Triphenyl Phosphate Content: Important for projects with stringent trace-component, migration, or regulatory requirements
Low-Triphenyl-Phosphate Grade: Stringent compositions can control triphenyl phosphate below 0.1%
Diisodecyl Phenyl Phosphate Content: Influences plasticization, viscosity, low-temperature behaviour, and flame-retardant balance
Residual Phenol: Controlled to limit odour, colour development, and downstream interference
Residual Isodecyl Alcohol: Controlled to limit volatility, odour, and composition drift
Acid Value: Important for polymer heat stability, metal compatibility, and reactive polyurethane systems
Moisture: Important for storage stability and moisture-sensitive polymer chemistry
Colour: Low APHA or Hazen colour is preferred for clear and lightly pigmented products
Phosphorus Content: Supports consistency of flame-retardant performance
Density, Viscosity and Refractive Index: Useful for identity, batch consistency, pumping, and process control
Pour Point: Relevant to storage and transfer in cold environments
A standard technical grade is suited to general flexible-PVC, coating, rubber, and polymer-additive applications.
Low-colour, low-acidity, low-moisture, and low-triphenyl-phosphate grades address applications with tighter processing, appearance, or trace-component requirements.
FORMULATION AND PROCESS CONSIDERATIONS
Iso-Decyl Diphenyl Phosphate can be metered directly or premixed with other liquid plasticizers and additives.
In PVC dry blending, adequate agitation and controlled warm mixing promote uniform absorption into the resin before cooling and downstream compounding.
The addition level is selected according to required hardness, low-temperature flexibility, flame performance, smoke behaviour, and mechanical properties.
Increasing phosphate ester concentration can improve plasticization and phosphorus loading but also changes tensile strength, elongation, extraction resistance, electrical properties, and compound cost.
PVC heat stabilizers, fillers, pigments, impact modifiers, and supplementary flame retardants should be balanced as a complete additive package.
Bench and production evaluations commonly include Shore hardness, tensile strength, elongation, limiting oxygen index, smoke generation, heat ageing, volatility, migration, extraction, and electrical testing.
Moisture and acid value require close control when the product is used with isocyanates or moisture-sensitive catalysts.
Strongly acidic or alkaline conditions can accelerate hydrolysis of the phosphate ester.
Prolonged exposure to excessive processing temperatures should be avoided to limit thermal decomposition and colour formation.
QUALITY, SPECIFICATIONS AND DOCUMENTATION
A Certificate of Analysis provides batch-specific results for the agreed commercial specification.
Important entries include appearance, colour, acid value, moisture, density, viscosity, refractive index, phosphorus content, and chromatographic phosphate-ester composition.
The Technical Data Sheet defines product identity, physical characteristics, functional profile, and processing context.
The Safety Data Sheet provides hazard classification, exposure controls, first-aid measures, storage conditions, spill procedures, and transport information.
Application-specific procurement can also require declarations covering regulated substances, inventory status, residual components, and composition thresholds.
For critical PVC, electrical, automotive, polyurethane, or coating projects, the purchasing specification should connect chemical parameters with the relevant finished-product performance tests.
SAFETY AND REGULATORY CONSIDERATIONS
Environmental Classification: Aquatic Chronic 4
Hazard Statement: H413, may cause long-lasting harmful effects to aquatic life
Acute Toxicity Profile: Low acute oral and dermal toxicity in test data
Primary Exposure Routes: Skin contact, eye contact, ingestion, and inhalation of mist from heated material
Combustibility: High-flash-point combustible liquid
Decomposition Products: Carbon oxides, phosphorus oxides, and irritating organic fumes
Direct eye or skin contact can cause temporary irritation.
Heated material can generate mist or vapour that irritates the respiratory system.
Good industrial hygiene and effective process ventilation reduce routine exposure.
The product is hydrophobic, has extremely low water solubility, and can adsorb strongly to soil and sediment.
It is inherently biodegradable under adapted aerobic conditions and does not meet the criteria for a persistent, bioaccumulative and toxic or very persistent and very bioaccumulative substance.
Release to drains, surface water, or soil should be prevented.
FIRST AID
Inhalation: Move the affected person to fresh air and obtain medical attention if respiratory symptoms persist.
Skin Contact: Remove contaminated clothing and wash the affected skin thoroughly with soap and water.
Eye Contact: Rinse cautiously with clean water for at least 15 minutes, remove contact lenses when easy to do, and obtain medical attention if irritation persists.
Ingestion: Rinse the mouth, do not induce vomiting, and seek medical advice.
Note to Physicians: Provide supportive and symptom-directed treatment.
HANDLING AND STORAGE
Use closed transfer systems or local exhaust ventilation where mist or heated vapour can form.
Avoid contact with the eyes, skin, and clothing.
Wear chemical-resistant gloves, safety goggles, and suitable protective clothing during transfer, sampling, and spill response.
Store in clean, dry, tightly closed containers in a cool and well-ventilated area.
Protect the material from moisture, direct heat, open flames, and prolonged exposure to high temperatures.
Keep it separated from strong oxidizing agents, strong acids, and strong bases.
For fire response, use alcohol-resistant foam, dry chemical powder, or carbon dioxide.
Water fog can cool exposed containers, but a direct water jet can spread burning liquid.
Firefighters should use self-contained breathing apparatus when decomposition fumes are present.
Contain spills with inert, non-combustible absorbent material and prevent entry into drains or waterways.
Collect recovered liquid and contaminated absorbent in suitable closed containers for controlled disposal.
Clean transfer areas promptly because residual liquid can create a slipping hazard.
PACKAGING AND PROCUREMENT CONSIDERATIONS
Iso-Decyl Diphenyl Phosphate can be supplied in sealed drums, intermediate bulk containers, and bulk quantities.
Clean, dry containers and transfer equipment compatible with organic phosphate esters help preserve colour, moisture, and acidity requirements.
The low pour point supports pumping and unloading under cold ambient conditions.
A complete procurement request identifies the chemical name, CAS number, intended polymer or process, required phosphate-ester distribution, triphenyl phosphate limit, acid value, moisture, colour, packaging format, order quantity, destination, and documentation requirements.
For formulation-sensitive projects, relevant information also includes processing temperature, target flame performance, low-temperature requirements, electrical properties, and applicable finished-product tests.
Ataman Kimya supports Iso-Decyl Diphenyl Phosphate requirements for flexible PVC, wire and cable, coatings, elastomers, specialty plastics, and industrial fluid formulations, with attention to grade selection, phosphate-ester composition, specifications, documentation, packaging, and supply planning.
For product information, application discussions, Certificates of Analysis, Safety Data Sheets, packaging, or commercial enquiries, contact Ataman Kimya.
+90 216 577 10 10
info@atamankimya.com
