TPU from POM-Polyether Polyols


 Number/Link: WO2015/155084  (German)

Applicant/Assignee: Bayer

Publication date: 15-10-2015

Gist”: Paraformaldehyde-PO polyols are used to make TPU

Why it is interesting: Polyoxymethylene (POM) is a highly crystalline ‘engineering thermoplastic’ often used in blends together with TPU. In this invention POM is not blended but used to make a POM-polyether ‘block’ diol which is then used to make TPU. The diol is prepared by using paraformaldehyde as a starter which is reacted with PO (and optionally CO2) using DMC catalysis. The POM-block acts as a ‘hard block’ and use of the diol allows for an improved control of Tg, melt viscosity, hardness, chemical resistance etc. of the TPU.  In the examples TPU is made from a 2000 MW parafomaldehyde/PO-CO2 block copolymer  together with 4,4’MDI and BDO.




Thermoplastic PU-PS Graft Copolymers


 Number/Link: WO2014/147194

Applicant/Assignee: BASF

Publication date: 25-09-2014

Gist”: TPU microparticles react with styrene monomer resulting in a TPU-PS copolymer.

Why it is interesting: Blends of TPU with polystyrene are known, but compatibility is low and PS to TPU ratio therefore needs to be low as well  to prevent ‘delamination’ of injection moulded parts.  According to this patent application it is however possible to graft the PS onto TPU such that much higher PS/TPU ratio’s can be obtained. The TPU needs to be MDI-based and have a relatively low hardblock content and softening temperature. Apparently the PS grafts onto the MDI methylene groups which form radicals easily. In an example TPU micropellets are swollen in styrene monomer at low temperature together with dicumulperoxide as a radical initiator. The swollen particles are then dispersed in water together with an emulsifier and heated under pressure to form a 60-40 TPU-PS copolymer. A solvent-based process is also exemplified.  The resulting polymers are especially useful for injection moulded parts such as spring-aids.

MDI radical

MDI radical

Expandable Polyurethane Particles for Insulation Panels


 Number/Link: WO2014/006182  (German)

Applicant/Assignee: BASF

Publication date: 9-01-2014

Gist”: Microgranules of TPU/PS copolymer containing pentane can be expanded into insulation panels using standard EPS equipment.

Why it is interesting: Contrary to polystyrene, thermoplastic polyurethane cannot be ‘imbued’ with a physical blowing agent like pentane to make steam-expandable particles. This is due a.o. to the high diffusion rate of pentane (e.g.) in TPU.  BASF have now found that by using a TPU/PS copolymer, expandable particles can be prepared which can be used in standard EPS (expandable polystyrene) equipment to make insulation panels. The TPU used is based on 4,4′-MDI, polyTHF and butanediol such that the vicat softening point is below 80°C.   The TPU, in the form of microgranules (0.5-2mm), is swollen in styrene containing dicumylperoxide, dispersed in water and heated to polymerisation.  A blowing agent like (pref) pentane is added to the dispersion as well. The resulting particles are expandable and can be used to make insulation panels of 50-150 kg/m³.

Expandable Polystyrene.

Expandable Polystyrene.

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