Urethane-Acrylate Latex

Patent Title: HIGH SOLIDS, LOW VISCOSITY URETHANE-LINKAGE CONTAINING LATEX AND METHOD OF PRODUCTION THEREOF

 Number/Link: WO2015/195466

Applicant/Assignee: Arkema

Publication date: 23-12-2015

Gist”: Simultaneous emulsion polymerization of acrylate, hydroxyacrylate and diisocyanate

Why it is interesting: According to this invention a low viscosity and high solid-content latex, containing urethane bonds, can be produced by emulsion polymerization of a diisocyanate  and a mixture of ethylenically unsaturated monomers some of which are isocyanate-reactive. In an example H12MDI is emulsified in water together with hydroxyethyl acrylate, a mixture of other acrylate monomers and an appropriate surfactant.  The emulsion is then polymerized using a peroxide. The resulting latex had a solid content of 52% at a visosity of 480 cP.  The latex is said to be especially useful for coatings with improved chemical resistance and toughness.

Hydroxyethyl acrylate

Hydroxyethyl acrylate

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Self-Cleaning Coating… or not?

Title: SELF-RENEWING HYDROPHILIC ORGANIC COATINGS

 Number/Link: US2014/018466

Applicant/Assignee: Empire Technology

Publication date: 16-01-2014

Gist”: Coating containing free amine groups resulting in a hydrophilic surface that is supposedly self-cleaning.

Why it is interesting: Conventionally “self-cleaning” surfaces are produced using hydrophobic coating compositions resulting in surfaces with low contact angles with respect to water.  The current case claims that highly hydrophilic surfaces also show a self-cleaning effect.  An emulsion-polymerized polymer with blocked-isocyanate side groups is used as a coating composition.  After the coating is applied the side groups are deblocked by atmospheric moisture resulting in (hydrophilic) amine groups.  In an example 2-methyl-acrylic acid 2-isocyanatoethyl ester blocked with 3,5-dimethylpyrazole was emulsion polymerized and, together with additives, used as a coating composition.
While this is fun chemistry I very much doubt that this coating would be truly self-cleaning.  The amine groups will surely react with all kinds of stuff in the air possibly resulting in quite the opposite.

deblocking of the isocyanate side groups under the influence of water.

deblocking of the isocyanate side groups under the influence of water.

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