Non-Isocyanate Polyurethanes from Thiocarbonates

Patent Title: PROCESS FOR THE MANUFACTURING OF A POLYMER WITH URETHANE GROUPS

Number/Link: WO2019/034470 and WO2019/034473

Applicant/Assignee: BASF

Publication Date: 21 February 2019

“Gist”:  A cyclic thiocarbonate is reacted with a diamine and then with a diacrylate

Why it is interesting: NIPU is prepared by reacting a five-ring monothiocarbonate with di- (or poly-) amine and then with a compound having at least two thiol-reactive functional groups like e.g. ethylenically unsaturated groups. The reaction has advantages over conventional PU chemistry like being isocyanate-free, less moisture sensitive and running at moderate temperatures. In an example methyl monothiocarbonate is reacted with 1,5-pentanediamine and 1,4-butandioldimethacrylate, resulting in a colourless, transparent polymer with a high thermal stability.
An interesting take on hybrid non-isocyanate polyurethanes.

scheme1

Reaction scheme according to the invention

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Classic PU Patent of the Month: Non-Isocyanate Polyhydroxyurethanes by Dow (1957)

Title: Polyhydroxyurethanes

 Number/Link: US3084140

Applicant/Assignee: Dow

Publication date: 2-04-1963

Gist”: bis-cyclocarbonates are reacted with aliphatic polyamines

Why it is interesting: Non-isocyanate polyurethanes (NIPU) are still gaining in popularity – at least in the patent and science literature. The chemistries to make NIPU are far from new as discussed in a previous ‘classic patent of the month’ on this blog.  The most common route to NIPU is by reacting cyclocarbonates with amines resulting in hydroxyurethanes, as was first dicussed in this patent. The intent of the invention was, actually, not to avoid the use of isocyanates but to make hydroxy-group containing polyurethanes which were said to be ‘highly desirable’:  the OH groups can act as points for crosslinking, make the resin more hydrophilic and compatible with certain materials etc.

Preparation of polyhydroxyurethanes according to the invention

Preparation of polyhydroxyurethanes according to the invention

Cooperative Catalyst System for NIPU

Title: Catalyst for Non-Isocyanate Based Polyurethane

 Number/Link:US2015/247004

Applicant/Assignee: Dow; Univ. Northwestern

Publication date: 3-09-2015

Gist”: The cyclocarbonate-amine reaction is catalysed by a lewis acid/lewis base combination

Why it is interesting: It is well known that polyhydroxyurethanes can be produced from cyclic carbonates and amines.  These “nonisocyanate polyurethanes” can have advantages over conventional polyurethanes, e.g. as coatings with improved chemical resistance. The reactivity of (especially 5-ring)  cyclocarbonates is however much lower than that of isocyanates making the reaction much less practical.  According to this invention that problem can be solved by using a ‘cooperative’ catalyst system consisting of a lewis acid and an organic lewis base. In an example a difunctional cyclocarbonate-capped prepolymer is reacted with 1,3-cyclohexane-bis(methylamine) catalysed by a mixture of  lithium trifluoromethanesulfonate and triazabicyclodecene.
It has been noted before in this blog that Dow, as one of the major isocyanate producers, also appears to be interested in non-iso PU.

Triazabicyclodecene.

Triazabicyclodecene.