Toluene Diisocyanate, Tolylene Diisocyanate, Methylphenylene Diisocyanate, TDI Isocyanate, TDI 80/20, TDI 80, TDI, 26471-62-5

Molecular Formula

C₉H₆N₂O₂

Molecular Weight

174.2 g/mol

CAS Number

26471-62-5

Chemical Name

Toluene Diisocyanate

Trade Name

TDI 80/20

Appearance

Colorless to pale yellow liquid or crystals

Odor

Sharp, pungent

Melting point

19.5 – 20.5 °C

Boiling point

247 °C

Flash point

137 °C

Density

1.22 g/cm³ (denser than water)

Vapor density

Heavier than air

Reactivity

Reacts with water producing CO₂; flammable; explosive vapor-air mixture when exposed to heat, flame, or sparks

Solubility

Soluble in acetone, alcohol, benzene, ethyl acetate, ether, carbon tetrachloride, chlorobenzene, kerosene, and various oils

Inhalation

High acute toxicity; chest tightness, shortness of breath, coughing; long-term sensitization (asthma-like) and antibody formation

Skin contact

Irritation, burns; wash immediately with plenty of water

Eye contact

Severe irritation, potential permanent damage

Ingestion

Severe irritation to gastrointestinal tract

High reactivity

High toxicity

Low molecular weight

Dangerous reaction with water (pressure buildup)

Essential intermediate for polyurethanes

Skin/respiratory sensitizer

Flammable

Furniture & Bedding

Most common use – flexible polyurethane foam (slabstock and molded). Used in sofas, mattresses, cushions, pillows for comfort and resilience.

Automotive

Vehicle seats, interior trim, steering wheel covers, sound insulation materials, and some mechanical parts (e.g., bumpers, bushings).

Construction & Building Materials

Thermal and acoustic insulation rigid foams, floor and wall coatings, sealants, and protective coatings.

Footwear Industry

Production of durable and comfortable polyurethane shoe soles, especially for sports and casual shoes.

Coatings & Paints

Varnishes, paints, protective coatings for wood, metal, and plastic surfaces. Provides film-forming properties and durability.

Adhesives & Sealants

Moisture-curing (one-component) adhesives – long open time, suitable for large surfaces. Also used for industrial rollers, gaskets, and elastomers.

Packaging

Flexible packaging materials, carpet backing, and packaging foams.

MDI (Methylene Diphenyl Diisocyanate)

Most direct alternative. Lower vapor pressure → less inhalation risk. Preferred for rigid foams and high-strength elastomers. TDI is still superior for flexible foams (softer, more resilient).

Aliphatic Diisocyanates (HDI, IPDI)

Used when UV resistance and non-yellowing properties are critical (e.g., automotive clearcoats, exterior paints). Higher cost than TDI.

Bio-based Polyols

Not a direct isocyanate replacement, but combined with TDI or MDI to reduce fossil carbon footprint. Derived from vegetable oils.

NIPU (Non-Isocyanate Polyurethane)

Emerging technology. Aims to produce polyurethanes without any isocyanates – eliminates toxicity issues. Not yet commercially widespread.

Prepolymer synthesis

TDI is reacted with a polyol in a controlled first step to form a prepolymer, which is later cured to final product. Most common method for elastomers and coatings.

Slabstock foam production

TDI, water, catalysts, and additives are mixed and poured into a large trough to rise into a continuous foam block. The block is then cut into sheets or shapes.

Molded foam production

The reactive mixture is poured into a closed mold to produce shaped parts (e.g., car seats, armrests).

Casting (for elastomers)

Prepolymer is cast into a mold and cured to produce solid parts (wheels, rollers).

Spray application

TDI-based systems are sprayed onto surfaces for insulation or coating (requires strict safety measures).

Flexible polyurethane foams

TDI provides an unmatched combination of softness, resilience, high load-bearing capacity, and processing ease. MDI gives firmer, less resilient foams.

Low-viscosity systems

TDI has relatively low viscosity → easier mixing with polyols and additives without needing special equipment or solvents.

Cost-sensitive mass production

TDI is cheaper than aliphatic isocyanates (HDI, IPDI) and, for flexible foams, more cost-effective than MDI-based formulations.

Moisture-curing adhesives (long open time)

TDI-based prepolymers allow very long open times (hours) before curing, which is essential for bonding large surfaces (e.g., sandwich panels, construction elements).

1

Toluene Diisocyanate

General chemical name (most common)

2

TDI 80/20

Commercial isomer mixture ratio (80% 2,4 – 20% 2,6)

3

2,4-Toluene Diisocyanate

One of the main isomers

4

2,6-Toluene Diisocyanate

The other main isomer

5

TDI

Abbreviation (very frequently used)

6

Tolylene Diisocyanate

Older / alternative spelling

7

Methylphenylene Diisocyanate

IUPAC‑like name

8

2,4-Diisocyanato-1-methylbenzene

Systematic IUPAC name

9

TDI 80

Short trade name (refers to 80/20)

10

TDI Isocyanate

General category search

1

Toluen Diizosiyanat

Most common Turkish chemical name

2

TDI 80/20

Searched with the ratio (common)

3

TDI

Abbreviation, widely used

4

2,4-Toluen Diizosiyanat

Main isomer

5

2,6-Toluen Diizosiyanat

Other isomer

6

Tolilen Diizosiyanat

Older / alternative Turkish spelling

7

Toluen -1,3-diizosiyanat

Systematic name

8

Metil Fenilen Ester

Appears in trade / technical literature

9

Diizosiyanato Toluen

Reverse order / alternative

10

TDI İzosiyanat

General category search