All posts tagged elastomers

Polyurethane with Thermally Reversible Crosslinks

Patent Title: THERMALLY REVERSIBLE CROSSLINKED POLYURETHANE

Number/Link: WO2016/018956

Applicant/Assignee: Lubrizol

Publication date: 4-02-2016

“Gist”: Diels-Alder adducts of furan and maleimide are used as reversible crosslinks

Why it is interesting: Polyurethanes with thermally reversible crosslinks can be useful: these materials can be processed and recycled as thermoplastics while showing increased mechanical properties and the reduced compression set of thermosets. They can also show self-healing properties in certain circumstances.
According to this invention PU with thermally reversible crosslinks can be prepared by reacting a diisocyanate with a diol containing a furan functional group and then incorporating a polymaleimide. For example: the diol can be prepared by reacting furfurylmethacrylate with thioglycerol and the polymaleimide can be 1,1′-(methylenedi-4,1-phenylene)bismaleimide.
Interesting idea but very similar to WO2015119688 discussed before.

1,1'-(methylenedi-4,1-methylene)bismaleimide

1,1′-(methylenedi-4,1-phenylene)bismaleimide

TPU Powder for SLS

Patent Title: USE OF THERMOPLASTIC POLYURETHANE POWDERS

Number/Link: WO2015/197515 (German)

Applicant/Assignee: Covestro

Publication date: 30-12-2015

“Gist”: TPU with very specific melt properties can be used for selective laser sintering

Why it is interesting: Additive manufacturing and “3D printing” using TPU is not new and has been mentioned before in this blog, e.g. the use of TPU in for fused deposition modelling. Fused deposition modelling is a technique where molten thermoplastics are extruded. In powder-based techniques on the other hand, thin layers of thermoplastic powder are selectively ‘sintered’ together using lasers or IR beams. Powder techniques like laser sintering are said to have economic advantages and allow for the production more complex shapes, but suffer from low mechanical properties and brittleness. According to this application, TPU powders with specific hardness and melt characteristics (as outlined in claim 1) allow for laser-sintered objects with improved mechanical properties. In the examples a TPU is prepared from a butanediol-adipic acid polyester diol, butanediol chain extender and 4,4’MDI. The TPU, together with some ‘fumed’ silica flow-improvement additive, is then cryogenically grinded to an average particle size of less than 150 micron and subsequently used for laser sintering.

Tetrahedron made by SLS (© Wikimedia)

Polyurethane Foams with Reduced Acetaldehyde Emissions

Patent Title: POLYURETHANES WITH REDUCED ALDEHYDE EMISSION

Number/Link: WO2015/189095

Applicant/Assignee: BASF

Publication date: 17-12-2015

“Gist”: A polymer with pending -O-NH2 groups is used as additive

Why it is interesting: The reduction of VOC emissions, especially emissions of aldehydes from PU foams, remains an important topic of research. A number of solutions have been proposed, for example the use of polyamines as scavengers as discussed before. There still appears to be a need for improvement however, especially for the reduction of acetaldehyde emissions. According to this invention acetaldehyde emissions can be reduced by using a relatively high mole-weight polymer with pending aminooxy groups as an additive during foaming. In an example a copolymer of 4-aminooxymethylstyrene and methacrylic acid with a Mn of about 15,000 is used as an additive.

4-aminooxymethylstyrene

Innovation in Polyurethanes

All posts tagged elastomers

Polyurethane with Thermally Reversible Crosslinks

TPU Powder for SLS

Polyurethane Foams with Reduced Acetaldehyde Emissions

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