TPU Foams

Title: POLYURETHANE FOAMS AND METHOD FOR PRODUCING SAME

Number/Link: US2017/0174818

Applicant/Assignee: Lubrizol

Publication Date: 22-june-2016 (PCT oct. 2015)

“Gist”: TPUs with specific MW and polydispersity are injection moulded together with cellopener and gas in supercritical state

Why it is interesting: The invention relates to injection moulded “flexible foams”, especially useful for footwear applications. Thermoplastic polyurethanes with a Mw of 120,000 to 500,000 and a dispersity index of 1.85 to 2.51 are foamed using a gaseous blowing agent (CO2 or C1 to C6 hydrocarbons etc. ) together with a cellopener (silicone or EO/PO surfactant), such that at least 50% of cells are open.  In the examples the blowing agent is added in supercritical state to the melt before injection moulding. The type of gas used, nor the densities of the foams are mentioned.  Foaming TPU with gas in supercitical has also been file by Nike as discussed before in this blog.

Nike shoe with foamed thermoplastic midsole

 

TPU from Oleic Acid

Title: RENEWABLY DERIVED THERMOPLASTIC POLYESTER-BASED URETHANES AND METHODS OF MAKING AND USING THE SAME

Number/Link: US2017/0145145

Applicant/Assignee: Trent University

Publication Date: 25-may-2017

“Gist”: Thermoplastic polyurethane made entirely from C9 monomers derived from oleic acid.

Why it is interesting: Azaleic acid can be prepared by oxidative cleavage of the oleic acid double bond.  Azaleic acid in turn can be converted to 1,9-nonanediol and to 1,7-heptamethyldiisocyanate via azides and Curtius rearrangment (see previous blog post). In this invention a polyester diol is prepared from azaleic acid and nonanediol and is then reacted with 1,7-heptamethylenediisocyanate together with nonanediol as chain extender, resulting in a phase-separated TPU. Best properties are obtained when the nonanediol is first prepolymerized with the diisocyanate. The TPU is said to degrade without cytotoxic degradation products, and is therefore useful for medical applications such as resorbable implants and scaffolds.
Related case: US2017/0145146.

Oleic Acid

 

Crystalline High-Hardblock TPU

Title: CRYSTALLINE HIGH MODULUS THERMOPLASTIC POLYURETHANE

Number/LinkWO2017079101  WO2017079188

Applicant/Assignee: Lubrizol

Publication Date: 11 May 2017

“Gist”: High-hardblock TPU using ‘stacking’ chain extenders and MDI

Why it is interesting: Thermoplastic polyurethanes with hardblock levels of 75% and higher were first patented by Upjohn in 1981 in a “classic” patent which has been discussed before in this blog. These materials – often marketed under the ‘ISOPLAST’ tradename- are usually produced from a diol, 4,4′-MDI and a (mixture of) chain extender(s) comprising a ‘non-stacking’ chain extender like cyclohexanedimethylol, neopentylglycol, MPdiol etc. to control crystallinity. In the current invention only ‘stacking’ chain extenders are used in an otherwise identical composition, resulting -unsurprisingly- in a more crystalline material with a higher modulus and melting temperature. It is also said that these materials are easier to compound with e.g. fire retardants.
Even if this idea were formally ‘new’ I doubt its inventiveness and therefore its patentability.

The famous ISOPLAST(TM) nail

TPU with Moisture-Controlled Flexibility

Title: THERMOPLASTIC POLYURETHANE MATERIALS FOR FORMING MEDICAL DEVICES

Number/Link: Wo2017/066381

Applicant/Assignee: Becton Dickinson

Publication Date: 20 april 2017

“Gist”: High hardblock TPU, based on side-chain branched chain extenders, softens in water

Why it is interesting: The invention is related to thermoplastic polyurethanes for medical applications especially for intravenous catheters. These catheters need to have a high stiffness when inserted but need to become flexible once in place to prevent injuries. This is accomplished with TPUs based on MDI, PTMEG and either 2,2-dimethyl-1,3-propanediol (neopentylglycol) or 2-methyl-1,3-propanediol (MPdiol) and having a hardblock content of 50 to 75%. The examples show indeed an increased stiffness at ambient conditions and a larger softening when soaked in saline solution compared to TPU produced with a linear chain extender. It is however not mentioned which linear chain extender was used.

Neopentylglycol

Low Density Foamed TPU

Patent Title: FOAMED THERMOPLASTIC POLYURETHANE AND MICROWAVE MOLDED ARTICLE THEREOF

 Number/Link: US2017/0073490

Applicant/Assignee: Sunko Ink; Tayin R&D

Publication date: 16-mar-2017

Gist”: Blown TPU pellets are subjected to a second foaming process using microwaves

Why it is interesting: Thermoplastic polyurethane is extruded together with an excess of blowing agent using a single screw extruder and a pelletizer. The foamed pellets are then put in a mould together with water and subjected to microwave radiation which causes the pellets to expand and sinter into a moulded part. In the examples expandable microspheres are used as blowing agent in amounts of 5 to 25 php of TPU. The pellets are irradiated for 20 to 180 s at a power of up to 5000 W. Moulded densities as low as 170 kg/m³ are achieved.

SEM picture of moulded TPU according to the invention