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.




Classic PU Patent of the Month: Scott Paper Co. on Reticulated Polyurethane Foams (1964)

Title: Reticulated polyurethane foams and process for their production

 Number/Link: US3171820

Applicant/Assignee: Scott Paper Co.

Publication date: 2-03-1965

Gist”: PU foams are reticulated by hydrolysis or explosion.

Why it is interesting:   Reticulated foams are foams from which the membranes have been removed so that only a three dimensional network of strands or ‘struts’ remains. These materials are commercially available in different grades of stiffness and porosity and are useful in applications such as filtering, sound absorbing, padding and the like. The current invention – filed in 1964 but a ‘continuation’ of an application filed in 1956- teaches the two processes to reticulate PU foam still in use today. The first process uses an aqueous NaOH solution to hydrolyse the cell membranes, in the second process a foam block is brought in an autoclave together with an explosive gas mixture (e.g. a mixture of oxigen and acetylene) which is then made to explode using a spark plug. When executed correctly the explosion removes all cell membranes leaving the struts intact. ‘Explosive recticulation’ is one of my all-time favorite PU inventions: simple, yet very effective and very courageous. In the current culture of hyper-safety where employees have to report paper-cuts, inventions like this are no longer possible.

Recticulate polyurethane foam

A recticulated polyurethane foam

Sound Absorbing PU-PA Foams


 Number/Link: US2014/058005

Applicant/Assignee: BASF

Publication date: 27-2-2014

Gist”: Rigid, open-celled and thermoformable polyurethane-polyamide foams are produced using short chain di-acids as both chain extender and blowing agent.

Why it is interesting: The reaction of a carboxylic acid group with an isocyanate group results in a mixed anhydride, which after releasing carbon dioxide forms an amide. Because the reaction is relatively sluggish a  Lewis base catalyst is used, e.g. N-methylimidazole. In this case a rigid foam-forming formulation based on MDI and (pref.) polyether polyols is further reacted with short chain diacids like azelaic- or glutaric acid.  The examples show foam densities of less than 30 kg/m³ without the use of water.  The foams are open celled with high air flow and with a Tg of around 90°C, making them thermoformable.  This type of foams is used as acoustic bonnet- en roofliners in the automotive industry.

Azelaic Acid

Azelaic Acid