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

 

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 polysters are said to be highly hydrolysis resistant in both acidic and basic environments.

Cyclohexane-1,1-dimethanol

Cyclohexane-1,1-dimethanol

TPU from HDI and H12MDI

Patent Title: NON-SOFTENING RESILIENT THERMOPLASTIC POLYURETHANES

 Number/Link: WO2016/054320

Applicant/Assignee: Lubrizol

Publication date: 7-04-1016

Gist”: TPU from a blend of HDI and H12MDI has improved creep and wet modulus

Why it is interesting: Polymeric materials used for in vivo medical applications like catheters, need to be hydrolytically stable and retain physical properties like stiffness, resilience, flexibility etc. in wet conditions.  It is known that conventional TPUs based on aromatic or cyclo-aliphatic isocyanates tend to show some softening in aqueous environments. For this reason copolyamides (COPAs) and polyether-block-polyamides (PEBAs) are often preferred over TPU for use in medical devices.  According to this invention, TPUs that can replace COPA and PEBA in medical applications can be produced using a blend of 1,6-hexanediisocyanate (HDA) and H12MDI. In the examples polyether TPUs, prepared from 2000MW polytetramethyleneether diol, butanediol and a 19:1 HDI:H12MDI isocyanate blend at harblock contents ranging from 15 to 50%, convincingly show improved creep properties and wet modulus when compared to conventional TPU and a commercial PEBA material.

H12MDI

H12MDI

Classic PU Patent of the Month: Scott Paper Co. on Reticulated Polyurethane Foams (1964)

Title: Reticulated polyurethane foams and process for their production

 Number/Link: US3171820

Applicant/Assignee: Scott Paper Co.

Publication date: 2-03-1965

Gist”: PU foams are reticulated by hydrolysis or explosion.

Why it is interesting:   Reticulated foams are foams from which the membranes have been removed so that only a three dimensional network of strands or ‘struts’ remains. These materials are commercially available in different grades of stiffness and porosity and are useful in applications such as filtering, sound absorbing, padding and the like. The current invention – filed in 1964 but a ‘continuation’ of an application filed in 1956- teaches the two processes to reticulate PU foam still in use today. The first process uses an aqueous NaOH solution to hydrolyse the cell membranes, in the second process a foam block is brought in an autoclave together with an explosive gas mixture (e.g. a mixture of oxigen and acetylene) which is then made to explode using a spark plug. When executed correctly the explosion removes all cell membranes leaving the struts intact. ‘Explosive recticulation’ is one of my all-time favorite PU inventions: simple, yet very effective and very courageous. In the current culture of hyper-safety where employees have to report paper-cuts, inventions like this are no longer possible.

Recticulate polyurethane foam

A recticulated polyurethane foam

Hydrolysis Resistant Polyester Polyurethane

Title: A POLYESTER POLYURETHANE MATERIAL WITH LONG TERM HYDROLYSIS RESISTANCE

 Number/Link: WO2014114614

Applicant/Assignee: Bayer

Publication date: 31-07-2014

Gist”: Hydrolysis resistant polyurethane elastomers can be prepared from sterically hindered polyester polyols together with a perchlorate salt.

Why it is interesting: Because of their high mechanical properties and abrasion resistance, polyester-based polyurethane elastomers are a material of choice in e.g. the footwear and automotive industries. Main drawback however is their susceptibility to hydrolysis which causes loss of physical properties in moist environments.  According to the current invention, hydrolysis resistance can be greatly improved by using a specific polyester polyol together with a perchlorate salt (e.g. 0.3% sodium perchlorate on the total composition). The polyester polyol is based on a diacid (e.g. adipic acid) and a mixture of diols one of which contains alkyl side groups (e.g. a mixture of butanediol and neopentylglycol).
The invention is actually a combination of two known ‘tricks’:  the neopentyl glycol will introduce some hydrophobicity and steric hindrance into the polyester backbone, and the perchlorate may have a weak coordination with the hydrolysable ester bonds thus forming a steric protection layer (at least according to Bayer’s own WO2013/030147). Because both effects are known and published I doubt that this is patentable.

Neopentylglycol

Neopentylglycol