Dispersions of Comb-Structured Polyurethanes

Patent Title: POLYURETHANE-BASED BINDER DISPERSION

 Number/Link: WO2016122569

Applicant/Assignee: Hewlett-Packard

Publication date: 4-08-2016

Gist”:  Aqueous dispersions of “1,2”-dihydroxypolyacrylate -based polyurethanes

Why it is interesting: According to this invention aqueous dispersions can be made of “comb -structured” polyurethanes which are based on polyols having two hydroxyl groups at one end of the chain.  The “1,2”-diols are made by copolymerizing (e.g.) methylmethacrylate and n-butylmethacrylate together with thioglycerol up to a Mw of about 2000. The polyols can then be reacted with isocyanate and dimethylolpropionic acid for dispersion in water. The dispersions are said to have a small average particle size (10-100 nm) and be especially useful as binders for inkjet-ink.

Thioglycerol

Thioglycerol

Polyurethane Dispersions with “Reversible Drying”

Title: RADIATION CURABLE AQUEOUS COMPOSITIONS WITH REVERSIBLE DRYING

 Number/Link: WO2014/111349

Applicant/Assignee: Allnex

Publication date: 24-07-2014

Gist”: PUDs from hydrophilic, low molecular weight PU can be re-dispersed after drying.

Why it is interesting: It is known that PUDs will coalesce into an insoluble film when dried, at least when the temperature is over the ‘minimum film forming temperature’ or MMFT.  This behaviour, while being useful in most coating- and adhesives applications, can be problematic when the PUDs are used for jet-printing inks because of irreverisble blocking of the print-head nozzles.  According to this invention re-dispersible PUDs can be made when the PU used is both sufficiently hydrophilic and of a low average molecular weight (pref. an Mn between 1000 and 5000, with a polydispersity between 2 and 4). The PU does need to be radiation curable so it can be crosslinked after drying.  In the examples a low NCO prepolymer is prepared from 1,6-hexanediisocyanate (HDI), 2,2-dimethylolpropionic acid, some polyester or polycarbonate polyol and an acrylic chainstopper like a propoxylated trimethylolpropane diacrylate. The (viscous) prepolymer is dispersed and neutralized by adding water containing NaOH or triethylamine. After drying the PUDs of the invention can be re-dispersed in water at 25°C.

Film-forming PU dispersion.

Film-forming PU dispersion.

Brominated Polyurethane Oligomers

Title: FLAME-RETARDING OLIGOMERIC BROMINATED URETHANE COMPOSITIONS

 Number/Link: US2013/0217286

Applicant/Assignee: Lubrizol

Publication date: 22-08-2013 (priority PCT)

Gist”: Use of highly brominated isocyanate-reactive monomers to prepare brominated PU oligmers useful as non-leaching fire retardants.

Why it is interesting: Brominated fire retardants are highly effective in polyurethanes but their use is being phased-out because of environmental issues and the production of some of them will be discontinued in the near future. Brominated PU oligomers can be used as fire retardants with less environmental problems as they are not fugitive and will leach less.  The oligomers can be produced using monofunctional highly brominated isocyanate-reactive monomers like tribromoneopentanol or pentabromophenol. Difunctional brominated monomers can also be using together with monofunctional isocyanates to control the molecular weight which is preferably between 800 and 20,000 (claimed).  The oligomers can be used as fire retardants in PU dispersions (claimed) and in other polyurethane compositions e.g. in TPUs.

pentabromophenol

pentabromophenol

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