All posts tagged chain extender

Liquid Crystalline Polyurethane Elastomers

Patent Title: LIQUID CRYSTALLINE POLYURETHANE ELASTOMER AND METHOD FOR PRODUCING SAME

Number/Link: US 2016/0376396

Applicant/Assignee: Toyo Tire & Rubber

Publication date: 29-dec-2016

“Gist”: Specific mesogenic diols are used together with high MW polyols and high functionality isocyanate

Why it is interesting: The invention is about thermotropic liquid crystalline PU elastomers, where the liquid crystalline (LC) phase is formed at relatively low temperatures (e.g. near room temperature). This is accomplished by preventing the mesogen to crystallize, such that it shows no melting point between its Tg and Ti (LC phase -to- isotropic phase transition temperature). This, in turn, is accomplished by using a high molecular weight polyol together with a high functionality isocyanate and a mesogenic diol of the structure shown below where Y represents -N=N-, -CO-, -CO-O- or -CH=N- and X represents a C3 to C20 alkylene. Under stress the elastomer extends in the orientation direction by increasing the LC content and shrinks by reducing LC content. It can therefore be used as a temperature-controlled actuator.

General structure of the mesogenic diol of the invention

Soft Ionomeric TPU

Patent Title: SOFTENING THERMOPLASTIC POLYURETHANES USING IONOMER TECHNOLOGY

Number/Link: US20160347900

Applicant/Assignee: Univ. Akron; Covestro

Publication date: 1-Dec-2016

“Gist”: TPU is prepared with ionomeric groups having bulky counter-ions

Why it is interesting: According to this invention a novel type of plasticized thermoplastic polyurethane can be made by incorporating as chain extender a diol containing an ionic group with a bulky counter ion. It is said that the steric hindrance of the bulky counter ions creates additional free volume that softens the polymer and lowers the melt viscosity. In the examples N,N-bis(2-hydroxyethyl)-2-aminoethane sulfonic acid (BES) is used together with bulky alkylammonium cations. The softest TPU shown has a 37 Shore A hardness at 25% hardblock content and 7.6 mole% BES-tetrakis(decyl)ammonium. This accounts for a 35 point hardness decrease compared to an ionomer-free control sample.

N,N-bis(2-hydroxyethyl)-2-aminoethane sulfonic acid

Polyrotaxanes in Flexible Foams

Patent Title: POLYOL COMPOSITION FOR PRODUCING FLEXIBLE POLYURETHANE FOAM..

Number/Link: US20160304689

Applicant/Assignee: Toyo Tire & Rubber

Publication date: 20-10-2016

“Gist”: Polyrotaxanes in PU foam reduces ‘wobble’ when used in car seats

Why it is interesting: The use of polyrotaxanes in polyurethanes is not new and has been discussed before in this blog. According to the current invention polyrotaxanes with OH-functional rings can be incorporated in flexible foams, where they are said to reduce tensile stress while having little impact on compressive properties. When these foams are used in (e.g.) vehicle seats that are subject to low frequency sideways vibrations, they should reduce the sense of “wobble” of the occupants. The theory is that under tension the rings slide along the axis molecule equalizing stresses. In the examples polyrotaxanes with 11000 to 20000 molecular weight PEG axis molecules are used with cyclodextrin rings having an OHv of 43 to 85.

Polyrotaxane-crosllinked polyurethane under stress (schematic)

Polyrotaxane-crosslinked polyurethane under stress (schematic)

Innovation in Polyurethanes

All posts tagged chain extender

Liquid Crystalline Polyurethane Elastomers

Soft Ionomeric TPU

Polyrotaxanes in Flexible Foams

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