All posts tagged glass transition

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

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by Gerhard Bleys on April 21, 2017  •  Permalink
Posted in Thermoplastics
Tagged , , , , , , , ,

Posted by Gerhard Bleys on April 21, 2017

https://purpatents.com/2017/04/21/tpu-with-moisture-controlled-flexibility/

Hydrolysis Resistant Polyester Urethane

Patent Title: HIGHLY DURABLE POLYESTER POLYOL

 Number/Link: US2017/0022143

Applicant/Assignee: Kuraray

Publication date: 26-jan-2017

“Gist”: PU from polyester polyol with bulky side groups

Why it is interesting: The invention is about polyester polyols prepared from a dibasic acid (e.g adipic acid) and a mixture of two diols: 3-methyl-1,5-pentanediol and cyclohexane-1,1-dimethanol. The diols are used in a molar ratio of about 1:1 (25-75 to 75-25 pref.). Polyurethanes prepared with these polyesters are said to be highly hydrolysis resistant in both acidic and basic environments.

Cyclohexane-1,1-dimethanol

Cyclohexane-1,1-dimethanol

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by Gerhard Bleys on January 27, 2017  •  Permalink
Posted in Elastomers, Polyols
Tagged , , , , , , , ,

Posted by Gerhard Bleys on January 27, 2017

https://purpatents.com/2017/01/27/hydrolysis-resistant-polyester-urethane/

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

General structure of the mesogenic diol of the invention

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by Gerhard Bleys on December 30, 2016  •  Permalink
Posted in Elastomers
Tagged , , , , , ,

Posted by Gerhard Bleys on December 30, 2016

https://purpatents.com/2016/12/30/liquid-crystalline-polyurethane-elastomers/

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