Breathable TPU Membranes


 Number/Link: WO2017/178482

Applicant/Assignee:  BASF

Publication date: 19-october-2017

Gist”: Semi-permeable membranes are made by phase inversion of all-hardblock TPU solutions

Why it is interesting: ‘Breathable” membranes show a high resistance to liquid water permeation (LEP) combined with a high water vapour permeability (WDD). According to this invention breathable polyurethane membranes can be prepared by dissolving an all-hardblock thermoplastic polyurethane in a polar, aprotic solvent (like N-methyl pyrrolidone) together with a water soluble compound, casting a film and coagulating the film with water. In the examples diisocyanates (MDI, TDI and HDI) are stoichiometrically reacted with chain extenders (MEG, BDO and HDO).  The resulting materials were schredded and dissolved in NMP together with some glycerol. 150 μm thick films were cast on glass and coagulated in water, resulting in membranes with an average pore size ranging between 4 and 500 nm.  The membranes are said to be useful to make breathable fabrics for outdoor wear e.g. (“Gore Tex” (TM) – type materials)






Monodisperse Polymer Polyol


 Number/Link: WO2017/172417

Applicant/Assignee:  Dow

Publication date: 5 october 2017

Gist”: Polymer polyol with a “monodisperse” particle size distribution is prepared by using a specific seeding dispersion

Why it is interesting: It is well known that the use of polymer polyols in flexible polyurethane foam formulations can result in improved airflow and load bearing properties. For optimal results the average particle size of the dispersed polymer needs to be similar to the cell wall thickness. According to this invention a SAN polymer polyol with a controlled and narrow particle size distribution can be prepared by using a seed dispersion which consists of an unsaturated macromer which, together with SAN particles of a particle size between 50 and 500 nm, is dispersed in a base polyol. The macromer is a PO/EO polyether with a (pref.) mole weight of 11000 to 14000 Da and having 4-5 OH groups and 1-2 reactive double bonds. The polymer polyol is prepared by dispersing the seed dispersion in the base polyol together with styrene, acrylonitrile and a solvent (e.g. isopropanol). After polymerization of the monomers the solvent is removed, resulting in a polymer polyol with at least 30% solids, average particle size of 1-3 μm and a size span of 1.25. In the examples the macromer is prepared by capping 1-2 OH groups of a 6-functional 90/10 PO/EO polyol with 3,3-isoprenyl-α,α-dimethylbenzylisocyanate.




TPU Aerosol


Number/Link: US20170198150

Applicant/Assignee: 3M

Publication Date: 13-july-2017  (priority PCT)

“Gist”: Aqueous dispersion of a hydrazide-extended  TPU can be sprayed as aerosol to make protective films

Why it is interesting: An aqueous thermoplastic polyurethane dispersion is prepared from a non-yellowing diisocyanate, e.g. bis(4-isocyanatocyclohexyl), a diol (e.g. PPG2000), a difunctional hydrazine or hydrazide chain extender (e.g. 1,3-diaminourea) and a water solubilizing compound (e.g. dimethylolpropionic acid).  Together with a propellant the, composition is shelf-stable and can be aerosol-sprayed to form clear, non-yellowing protective films.

3M’s aerosol-sprayed protective film.

Preventing Ostwald Ripening in Rigid PU Foams


Number/Link: WO2017093058  (German)

Applicant/Assignee: Evonik

Publication Date: 8 June 2017

“Gist”: Perfluorinated hydrocabons reduce Ostwald ripnening in PU foam formulations

Why it is interesting: Polymeric foams form by nucleation and growth of gass bubbles in the reacting mixture followed by (or simultaneous with) ageing of the bubbles through coalesence and Ostwald ripening, i.e. the growth of larger bubbles at the expense of smaller bubbles. Ostwald ripening ultimately results in fewer and larger cells, which has a negative effect on the thermal insulation properties of rigid foams. According to this invention the ripening effect can be prevented or reduced by incorporating in the foam formulation an “Ostwald hydrophobe”, i.e. a highly hydrophobic liquid which is largely immiscible with the reacting mixture. Examples of such liquids are perfluorinated hydrocabons with a boiling point of less than 150°C, e.g. perfluoropentane, perfluorocyclohexane and perfluoroisohexene (used in the examples).



Matte, Self-Healing Polyurethane Powder Coatings


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