Page 178 - CW E-Magazine (11-3-2025)

Special Report

industrial coating applications; and
electrostatic powder coatings. The IPDI
trimer can be used in non-yellowing,
high performance PU coatings for vari-
ous applications such as automotive
refinish.

Production
Today, there are mainly two pro-
duction methods for IP, a liquid- and a
vapor-phase process.

The three reaction steps are:
1. Aldol condensation of two mole-
cules of acetone to mesityl oxide;
2. Michael addition of mesityl oxide
and acetone to form 4,4-dimethyl-
heptane-2,6-dione; and
3. Intramolecular aldol condensation
of 4,4-dimethylheptane-2,6-dione
to IP.

Catalytic self-condensation of
acetone is a very complex reaction,
and numerous products are possible
via competitive self-condensation and
cross-condensation between the same
Fig. 1: Derivatives of IP(1)
Table 1: Application sectors for IPDI(2) or different ketones that are formed
in the reaction. All the major products
Sector Applications of the reaction – diacetone alcohol,
Surface treatment agent Leather finishing agent. mesityl oxide, phorone, mesitylene,
Coatings Automotive OEM & refinish coatings; industrial isophorone, 3,5-xylenol and 2,3,5-tri-
protective coatings; plastic coatings; wood coatings; methylphenol – find important indus-
steel coil and can coatings. trial applications. The selectivity of
Polyurethane(PU) resins Synthetic leather, PU acrylic resin, PU epoxy resin, PU the reaction for the desired product is
achieved by proper choice of catalyst
elastomers. and experimental conditions.
Adhesives Footwear adhesives, packaging adhesives, magnetic
card adhesives, binders. The reaction is catalysed by acids
Inks Ink binders, screen printing inks, alkyd inks, cigarette pack as well as bases, and it can be carried
inks, food packaging inks, hot stamping inks, UV inks. out in both liquid and vapour phases.
Gloves Wetting agents for gloves. Today, the liquid-phase process is the one
Others Rocket propellants, crosslinkers. most commonly operated on a production
scale; however, the disadvantage of the
C=N double bond in such a way that a possibility to design molecular struc- liquid-phase process is corrosion, while
myriad of commercial products can be tures for specific materials. the vapor phase process has a higher
obtained from reactions with alcohols, energy demand. The production process
carboxylic acids, and amines. Due to IPDI is used in the production of of ADIs, in general, is relatively long.
its primary and secondary isocyanate aliphatic polyisocyanates and polyure- It involves complex organic synthesis,
groups, it allows controlled polyaddi- thanes with high stability, with applica- phosgenation and other processes.
tion with polyols, which provides the tions in paints; varnishes; elastomers; It is not only technically difficult, but

178 Chemical Weekly March 11, 2025

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