Polyurea dispersion polyols

Polyurea dispersion polyols (PHD polyols, Polyhamstoff Dispersion polyols) were developed by Mobay Corp. (151). PHD polyols are usually... 

PHD (polyharnstoff dispersion) or PUD (polyurea dispersion) polyols have been introduced by Bayer-Mobay as an alternative to... 

Another family of polyols is the filled polyols.llb There are several types, but die polymer polyols are die most common. These are standard polyether polyols in which have been polymerized styrene, acrylonitrile, or a copolymer thereof. The resultant colloidal dispersions of micrometer-size particles are phase stable and usually contain 20-50% solids by weight. The primary application for these polyols is in dexible foams where the polymer filler serves to increase foam hardness and load-bearing capacity. Other filled polyol types diat have been developed and used commercially (mainly to compete with die preeminent polymer polyols) include the polyurea-based PEID (polyhamstoff dispersion) polyols and the urethane-based PIPA (poly isocyanate polyaddition) polyols. 

PHD polymer polyols are a special class of filled polyols developed successfully by Bayer, PHD being the abbreviation of the German name polyharnstoff dispersion or polyurea dispersions [67-69]. PHD polyols contain organic urea, oligomeric or polymeric polyurea, finely dispersed in liquid polyether polyols [67-73]. The difference between PHD polyols and graft polyether polyols is the different nature of the solid polymer dispersed (it is a heterocatenary polymer - polyurea - instead of carbocatenary polymer) which is obtained by another synthetic procedure (polyaddition reaction between a diisocyanate and a diamine instead of radical polymerisation). The reaction between the diisocyanate and the diamine, takes place in situ (reaction 6.19), in liquid poly ether. The resultant polyurea being insoluble in polyether, precipitates in the form of very fine particles ... 

A very unconventional way to obtain a polyurea dispersion is to react gaseous carbon dioxide, at higher pressures (> 20 MPa) and at around 50 °C, with diamines dissolved in liquid polyether polyols [74] ... 

In Chapter 3, the chemistry and technology of the most important oligo-polyols used for elastic polyurethanes fabrication, in fact high MW oligomers (2000-12000 daltons) with terminal hydroxyl groups and low functionality (2-4 hydroxyl groups/mol) were discussed. Polyalkylene oxide polyols (homopolymers of PO or copolymers PO - EO, random or block copolymers), polytetrahydrofuran polyols, filled polyols (graft poly ether polyols, poly Harnstoff dispersion - polyurea dispersions (PHD) and polyisocyanate poly addition (PIPA) polyols), polybutadiene polyols and polysiloxane polyols were all discussed. The elastic polyurethanes represent around 72% of the total polyurethanes produced worldwide. 

An alternative stable interactive organic dispersion in polyol has recently been introduced. This consists of particles of polyurea dispersed in polyol, formed by the in situ polyaddition reaction of isocyanates with amines in a polyol medium, and offers similar advantages to the polymer/polyols. 

There are two classes of polyols used in PU synthesis polyesters and polyethers. Approximately 90% of all PUs are manufactured using polyether polyols. Many polyols can be modified to have a higher degree of primary hydroxyl groups, or to contain one of polyurea or PU dispersions.The primary polyols are more reactive and the dispersed polyurea and PU segments serve to increase the crosslinking of the finished PU. Most of the polyether polyols... 

Many of the same basic raw materials shown in Table II for RIM fascia systems are also used in high modulus systems. Additionally, however, polyether polyols "filled" with dispersions of polyureas are used( 2) These are the so-called PHD polyols developed by Bayer AG, the PHD being an abbreviation for Polyharnstoff-Dispersion. These polyols provide the same "filler" effect as the graft polyols (Table II) for increasing the modulus of the polymer without increasing the amount of extender. 

Polymer polyols are defined as very fine and stable dispersions of solid polymers (vinylic polymers and copolymers, polyurea, polyurethanes) in liquid polyethers. Currently polymer polyols represent one of the most important group of polyolic intermediates for elastic polyurethanes [1-10]. 

Very interesting PHD polyols are obtained by the reaction in polyether media of TDI with primary amines and, instead of polymeric polyurea, organic diurea compounds are generated, insoluble in polyethers, in the form of a very fine dispersion. Example of amines used include ammonia, anilines and substituted anilines, and fatty amines (reactions 6.22 and 6.23). 

More recently, filled polyethers (so called polymer polyols ) have been introduced. These contain dispersed organic filler such as acrylonitrile-styrene copolymer or polyurea, some of which is grafted on to the polyether chain. Filled polyethers are used principally for flexible foams of high resilience. 

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