Matte, Self-Healing Polyurethane Powder Coatings

Title: POLYURETHANE COATING COMPOSITION

Number/Link: WO2017/074835

Applicant/Assignee: Valspar

Publication Date: 4 May 2017

“Gist”: Coating composition comprising isocyanate and two polyester polyols having a similar Tg but a widely different equivalent weight.

Why it is interesting: Conventionally low gloss or “matte” coatings are the result of a microtextured surface achieved by certain fillers or by incompatible polymers and the like. According to this invention “ultra matte” finishes can also -surprisingly- be achieved from a (powder) coating composition comprising a (blocked) isocyanate and a mixture of two polyester polyols. Both polyols have a Tg between 40 and 60ºC prefereably differing not more than 5 to 8ºC, while the OHv of the first polyol is between 150 and 325 and that of the second between 15 and 35.  The ratio between first and second polyol is from about 1:1 to 1:3 w/w. Also surprisingly, the resulting coatings are said to show self-healing properties. An interesting composition but no examples of the polyesters or isocyanates used are given.

Car with matte finish

One Component Polyurea

Patent Title: CYCLIC DYNAMIC POLYUREAS FOR POLYMERIC UREA PROCESSING

 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

 

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