Steam-Treated Polyisocyanurate


 Number/Link: WO2014/160616

Applicant/Assignee: Dow

Publication date: 2-10-2014

Gist”: Treating PUR-PIR with hot water at superatmospheric pressure results in a Tg increase.

Why it is interesting: Fiber-reinforced phenol-formaldehyde composites are used to make pipes among other things.  They are however not completely stable in hot humid conditions so that they are less well suited for off-shore piping systems for example. According to this patent application, polyisocyanurate (PIR) or polyurethane-polyisocyanurate (PUR-PIR) systems are more suitable materials for such applications because properties of these materials remain stable and -surprisingly- glass transition temperature increases when subjected to high pressure water or steam. In the examples PUR-PIR systems based on polymeric MDI submerged in water at 120°C and 3500 kPa for 7 days show indeed an increase in Tg.  In my opinion it would be interesting to repeat the experiment with 4,4′-MDI based PUR/PIR.  Because 4,4′ MDI will show a higher conversion rate to PIR the ‘steam effect’ may well dissapear.

Isocyanurate group

Isocyanurate group

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