Hydrolysable Ureas


Number/Link: WO2017/155958

Applicant/Assignee: Univ. Illinois

Publication Date: 14 September 2017

“Gist”: Hindered urea bonds with fast hydrolysis kinetics are prepared from aromatic-sbstituted diamines and diisocyanates

Why it is interesting: Polyurethanes containing thermally reversible hindered urea bonds (HUBs) have been discussed before in this blog. In the current case the HUBs are prepared from aromatic (e.g aryl-) substituted amines and are said to show fast, pH-independent, hydrolysis kinetics. The HUBs can be built into linear or crosslinked polyurethanes or other polymers like polyamides, polycarbonates etc.  The resulting materials are useful for medical applications like drug delivery, water-degradable packaging, self-healing materials and the like.

HUB hysdrolysis

Hydrolysis reaction of phenyl-N-tetrabutyl-N-ethyl urea


One Component Polyurea


 Number/Link: WO2016/126756

Applicant/Assignee: University of Illinois

Publication date: 11-08-2016

Gist”: 1K polyurea coatings from thermoreversible cyclic urea oligomers

Why it is interesting: This application is related to W02016/069582 of the same applicant, discussed before on this blog. In this case the sterically hindered ureas are prepared in solvent and at a relatively low concentration. Under these conditions cyclic oligomers will be formed which can be separated and used as powder coatings, or, together with (e.g.) catalysts, polyols and crosslinkers, as liquid coatings. When heated the rings will open and the coating composition will cure. In an example 1,3-bis(isocyanatomethyl)cyclohexane  is reacted with N,N’-di-t-butyl ethylenediamine, in DMF, which forms cyclic oligomers at low-, and linear polymers at high concentrations.

Thermoreversible polyurea according to the invention

Thermoreversible polyurea according to the invention


Classic PU Patent of the Month: Polyurethane-Polyurea RIM Elastomers (Bayer 1976)


 Number/Link: DE262295 (German)

Applicant/Assignee: Bayer

Publication date: 24-11-1977

Gist”: Use of DETDA  in one shot PU-PUA RIM.

Why it is interesting: This is the invention that for the first time allowed the production of large reaction injection moulded (RIM) polyurea articles with a very short demould time. Apart from advances in mixing head design which allowed for fast and accurate mixing and advances in mould design, polyurea RIM was made possible by the development of specific diamine chain extenders.  Bayer found that aromatic diamines containing one alkyl group in o-postion to a first amino group and two alkyl groups in o-position to a second amine group, where at least two of the alkyl groups contain 2 or more carbon atoms, have the correct reactivity for a one shot RIM process when used together with conventional polyether polyols, MDI and catalysts. A preferred example of such a diamine is diethyltoluenediamine (DETDA). The use of DETDA in one shot RIM allowed for the production of  parts up to 10 kg with a demould time of 30 seconds.



Renewable Polyurea from Lysinol


 Number/Link: US2014/275311

Applicant/Assignee: Du Pont

Publication date: 18-09-2014

Gist”: Use of lysinol as renewable monomer for nitrogen-containing polymers including polyurea.

Why it is interesting: Lysinol or 2,5-diamino-1-hexanol is an amino alcohol derived from the amino acid lysine by  hydrogenation.  Lysine itself is produced by fermentation from sugars.  Annual production of lysine is apparently in excess of 1 million tonnes and its derivative lysinol is therefore considered as a potentially interesting biorenenawable monomer for a number of nitrogen-containing polymers. This patent application claims lysinol-based polyamides, polyimides, polyureas and “urethane crosslinked” polyureas including foams. In the examples urethane-polyureas are produced by reacting lysinol with hexamethylenediisocyanate using DABCO as catalyst.

Preparation of the two lysionol enantiomers from lysine.

Preparation of the two lysinol enantiomers from lysine.

Classic PU Patent of the Month: Otto Bayer’s Invention of Polyurethane and Polyurea (1937)

Title: Verfahren zur Herstellung von Polyurethanen bzw. Polyharnstoffen

Number/Link: DE728981  (German)

Applicant/Assignee: I.G.Farbenindustrie

Publication date: 12-11-1942

Gist”: Production of polyurethanes by reacting diisocyanates and compounds containing at least two hydroxyl and/or amine groups.

Why it is interesting: This is the patent that marked the start of the polyurethane industry.   It covers both aromatic and aliphatic diisocyanates, notably NDI, MDI, TDI, HDI etc. The examples cover polyurethane and polyurea fibers and films. It is said that Bayer was trying to copy Nylon 6,6, the structure of which is very similar to a PU based on 1,6 hexanediol and 1,6 hexanediisocyanate.  The patent has only one claim:

Verfahren zur Herstellung von Polyurethanen bzw. Polyharnstoffen, dadurch gekennzeichnet, daβ man organische Diisocyanate mit solchen organischen Verbindungen
zur Reaktion bringt, die mindestens 2 Hydroxyl- oder Aminogruppen mit austauschbaren Wasserstoffatomen oder mindestens eine Hydroxylgruppe und mindestens eine Aminogruppe ,der genannten Art enthalten.”

Dr. Otto Bayer (1902-1982)

Dr. Otto Bayer (1902-1982)