1,4-Cyclohexane Diisocyanate

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Abbreviations: CHDI

Synonyms: 1,4-Diisocyanatocyclohexane, Cyclohexane-1,4-diisocyanate, trans-1,4-Cyclohexane diisocyanate

Molecular Formula: C₈H₁₀N₂O₂

Molecular Weight: 166.18

CAS Number: 2556-36-7

EINECS Number: 219-869-4

Trans-1,4-Cyclohexane diisocyanate CAS number: 7517-76-2.

Structural Formula:

Physical and Chemical Properties

Physical and Chemical Properties The industrial product is trans-CHDI, a white waxy solid at room temperature, insoluble in water. It does not easily form dimers, so its stability is better than PPDI in an environment isolated from air and moisture. Typical physical properties of trans-cyclohexane diisocyanate products are shown in Table 1-21.

Table 1-21 Typical Physical Properties of trans-Cyclohexane Diisocyanate Products

Characteristics and Uses

CHDI is a special diisocyanate with a compact and symmetrical molecular structure, forming a tight hard segment in polyurethanes. Polyurethane elastomers based on CHDI have excellent high-temperature dynamic mechanical properties (low thermal hysteresis), light and color stability, solvent resistance, abrasion resistance, and hydrolysis resistance. The softening temperature can be as high as 270°C, and the glass transition temperature can be as low as approximately -80°C. These polyurethane elastomers are particularly suitable for warm and oily environments, and applications requiring abrasion and tear resistance. This material is primarily used in medical-grade polyurethane elastomers requiring dynamic and biostable properties. Other applications include seals, conveyor belts, hoses, coatings, and films for automotive, mining, industrial, and medical devices.

It is recommended to heat and melt CHDI to 80–100°C before use, then add it to the dehydrated oligomeric polyol. The reaction should be carried out at 100°C for 30–45 minutes to obtain the prepolymer. For casting the elastomer, it is recommended to cure at 120°C for 16 hours, followed by post-curing at 130°C for 15–24 hours, and then allowing it to stand at room temperature for one week to achieve optimal final properties.