Fingerprint Resistant Coatings

Patent Title: COATINGS COMBINING OIL-ABSORBING AND OIL-REPELLING COMPONENTS FOR INCREASED SMUDGE RESISTANCE

 Number/Link: WO2018/032356

Applicant/Assignee:  HRL Laboratorories

Publication date: 15 February 2018

Gist”: Phase separated polyurethanes with oleophilic dispersed phase and oleophobic continuous phase (or vice versa) behave as anti-smudge materials.

Why it is interesting: Anti-smudge coatings are of great interest for smartphones and other touch screen devices and are currently made from oleophobic materials, i.e. materials showing a small contact angle vs. oils. According to this invention improved anti-smudge properties can be achieved by using a material having discrete inclusions in a continuous matrix. The matrix material needs to be oleophilic, while the inclusions are oleophobic (or vice versa) and the inclusions need to be smaller than 50nm so not to scatter visible light.  A coating like this can be prepared from a segmented polyurethane comprising (e.g.) a polybutadiene soft phase and a perfluoro/isocyanate/TMP hard phase. It is said that the oleophobic phase will repel the oil while the oelephilic phase will absorb it, leaving a smudge-free surface.
Question remains what happens when the oily phase gets saturated..

smudgecoating

Schematic representation of the invention

Fluorinated Thermoplastic Polyurethanes

Patent Title: SHOE UPPERS & CASE FOR PORTABLE DEVICES

 Number/Link: WO2018/007359  WO2018007360

Applicant/Assignee:  Solvay

Publication date:  11 January 2018

Gist”:  F-TPUs are prepared by incorporating perfluoro diols

Why it is interesting: The current inventions are about fluorinated TPU and its applications. The F-TPUs are prepared by replacing part of the polyol with hydroxyl-ended fluorinated polyethers. In the examples fluorinated polyether diols are used in different ratios to conventional polyester-, PTMEG-, CAPA- and polycarbonate diols and reacted with MDI or HDI and BDO or HDO as chain extenders. The F-TPUs can be used as uppers for footwear and as cases for smartphones and are said to have improved stain resistance and – surprisingly- a soft feel to the touch.

case

F-TPU smartphone case

 

TPU with Anti-Biofouling Surface

Patent Title: ANTIFOULING COMPOSITION

 Number/Link: WO2017/007899

Applicant/Assignee: BASF

Publication date: 12-jan-2017

Gist”: TPU containing silicone diol and having microstructured surface

Why it is interesting: Biofouling of surfaces e.g. in the marine environment or of medical implants is a problem.  For example the growth of barnacles on the hulls of vessels, subsea cables, pipes and energy generating structures has a significant economic impact. According to this invention, thermoplastic polyurethane articles with a surface energy of about 20 mN/m and a microstructered surface topography show an improved resistance to biofouling. The TPU is produced by incorporating 5-15% on the total composition of a PDMS diol with a OH value of 15 to 150, and by pressing onto the surface a 3D topology with ‘peaks’ and ‘valleys’ of an order of magnitude of 10μm.

Microstructured surface according to the invention

Microstructured surface according to the invention

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.