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

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Non-Isocyanate Polyurethane Using Thiol-Ene “Click Chemistry”

Title: POLY(HYDROXYL URETHANE) COMPOSITIONS AND METHODS OF MAKING AND USING THE SAME

 Number/Link: US20140182784

Applicant/Assignee:  Inventors but with US goverment interest

Publication date: 3-07-2014

Gist”: Crosslinked poly(hydroxyurethanes) are prepared by reacting a cyclic carbonate comprising a carbon-carbon double bond, a di-thiol and a polyamine.

Why it is interesting: According to this invention hydroxyurethanes are produced by first reacting a cyclic carbonate which has a double bond (e.g. 4-vinyl-1,3-dioxolan-2-one) with a dithiol (e.g. 1,6-hexanedithiol) using UV radiation and a UV initiator. The resulting di-carbonate is then reacted with a polyamine (e.g. diethylene triamine) resulting in a crosslinked poly(hydroxyurethane). Alternatively the carbonate-amine reaction can happen before the thiol-ene ‘click’ reaction. The materials can be used for binders and adhesives a.o.  The reactions have the advantage of being solvent-, catalyst- and isocyanate-free and having a high yield.

Thiol-ene reaction followed by carbonate-amine reaction

Thiol-ene reaction followed by carbonate-amine reaction

Highly Stable Isocyanate Dispersions

Title: STORAGE-STABLE HYDROPHILIC POLYISOCYANATES

 Number/Link: WO2014/053269   (German)

Applicant/Assignee: Evonik

Publication date: 10-04-2014

Gist”: A uretdion-containing isocyanate prepolymer is reacted with a neutralized aminealkylsulfonic acid to produce a novel hydrophilic (latent) isocyanate which can be used in stable aqueous dispersions.

Why it is interesting: Aqueous dispersions of isocyanates are useful in many applications as adhesives, binders, crosslinkers etc, but usually suffer from a relatively short shelf life.  Dispersions prepared according to the current invention supposedly lose less than 30% of their initial NCO value after 12 weeks storage at 50°C. In an example an aceton-solution of  an IPDI-uretdion prepolymer with an isocyanate content of 1.5% is reacted with the sodium salt of an aminealkylsulfonate in water to an NCO value of 0.1%. After removal of the aceton the resulting dispersion had a latent isocyanate content of 4.5%

Dimerization of isocyanate to uretdion.

Reversible dimerization of isocyanate to uretdion.

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