Reactive TPU for AM

Patent Title: REACTIVE THERMOPLASTIC POLYURETHANE BASED ON BLOCKED ISOCYANATES

 Number/Link: WO2018/149977

Applicant/Assignee:  BASF

Publication date: 23 August 2018

Gist”: Low molecular weight TPU with blocked isocyanate groups is useful for 3D printing

Why it is interesting: The invention is related to relatively low MW ( up to 40,000Da) thermoplastic polyurethanes with thermolabile end groups and a melting point of about 100ºC (pref).  The TPU has a low melt viscosity and after de-blocking (at pref. about 150ºC) the isocyanate groups can react with chain extender present, resulting in increased MW and related properties. The TPU can be prepared by partially blocking diisocyanates (with e.g. caprolactam) and then reacting in one shot or prepolymer system with polyols and chain extenders. In powder form the TPUs are said to be useful in additive manufacturing (AM) processes.

caprolactam

Caprolactam

Polyurethane-Acrylate Plastisol

Patent Title: ACRYLIC-URETHANE IPN PLASTISOL

 Number/Link: US2016/0152857

Applicant/Assignee: Polyone

Publication date: 2-06-2016

Gist”: Plastisols from blocked-iso grafted acrylate in plasticizer

Why it is interesting:
Conventional plastisols are suspensions of PVC particles in a (usuallly phthalate-) plasticizer. The suspension can be cured by heating, which results in a plasticized elastomer.  Plastisols are used for coatings of e.g. car underbodies and for ‘screen printing’ of textiles. According to this invention a non-PVC plastisol can be produced by dispersing core-shell acrylate polymer particles (Mn between 300,000 and 1,000,000) with blocked isocyanate groups grafted to the backbone into a plasticizer, preferably into dioctylphthalate, together with a latent amine crosslinker like adipic dihydrazide. No information is given about the blocking agent but the plastisol is said to cure at 130-170°C and be especially suited for textile printing.

Adipic dihydrazide

Adipic dihydrazide

Dual-Cure PU for 3D Printing

Patent Title: POLYURETHANE RESINS HAVING MULTIPLE MECHANISMS OF HARDENING FOR USE IN PRODUCING THREE-DIMENSIONAL OBJECTS

 Number/Link: US2016137839

Applicant/Assignee: Carbon3D

Publication date: 19-05-2016

Gist”: Isocyanates are blocked with ethylenically unsaturated blocking agents

Why it is interesting: This invention relates to additive manufacturing of 3D objects using photocurable liquids. The liquid consists of a diisocyanate, or a difunctional isocyanate-ended prepolymer, which is blocked with an ethylenically unsaturated blocking agent, for example t-butylaminoethylmethacrylate (TBAEMA). The photocurable liquid further comprises a diol (or diamine), a photoinitiator and a ethylenically unsaturated diluent, for example a methacrylate or a styrene.  The liquid can then be selectively cured into an intermediate solid 3D object by irradiation with UV light using conventional “printing” methods. After an optional washing stage the intermediate object can be finally cured using heat.

TBAEMA

TBAEMA

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.