All posts by Gerhard Bleys

Isocyanate-Free Polyurethanes Using Azide-Alkyne Click Chemistry

Title: SYNTHESIS OF POLYURETHANE POLYMERS VIA COPPER AZIDE-ALKYNE CLICK CHEMISTRY FOR COATINGS, ADHESIVES, SEALANTS AND ELASTOMER APPLICATIONS

 Number/Link: WO2014/122153

Applicant/Assignee: Sika

Publication date: 14-08-2014

“Gist”: Polyurethane prepolymers capped with azides and alkynes are reacted using copper catalysis.

Why it is interesting: Because of safety, health and envriromental issues, isocyanate-free systems have clearly been gaining in importance the last few years.  Especially for coatings, adhesives and OCF applications, alternative curings systems are being developed. In the current invention an isocyanate-free system is based on the reaction between a prepolymer having at least two azide groups and a prepolymer having at least two alkyne groups. The reaction is copper catalyzed such that it can be performed at ambient temperature. The first prepolymer is (pref.)  prepared by reacting an isocyanate ended prepolymer with glycidol (2,3-epoxy-1-propanol) and subsequently with sodium azide. The second prepolymer is similarly prepared by reacting an isocyanate ended prepolymer with propargyl alcohol (2-propyn-1-ol).  The systems are said to be especially useful for roof coatings.

Example of an azide-alkyne reaction resulting in 1,4-disubstituded triazoles.

Example of an azide-alkyne reaction resulting in 1,4-disubstituded triazoles.

 

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by Gerhard Bleys on August 18, 2014  •  Permalink
Posted in Adhesives-Coatings, Isocyanates and Prepolymers, Uncategorized
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Posted by Gerhard Bleys on August 18, 2014

https://purpatents.com/2014/08/18/isocyanate-free-polyurethanes-using-azide-alkyne-click-chemistry/

Hydrophobic and Clear Thermoplastic Polyurethane

Title: CLEAR HYDROPHOBIC TPU

 Number/Link: WO2014/121174

Applicant/Assignee: Lubrizol

Publication date: 7-08-2014

“Gist”: A hydrophobic, clear and low density TPU is prepared from 4,4’MDI, a dimer acid-based polyol and a mixture of “non-stacking” chain extenders.

Why it is interesting: Most commercial TPUs are hydrophilic to a certain extend and because of phase separation and partial crystallization are often transparent but not clear. The current invention teaches a highly hydrophobic and clear TPU made form 4,4′ MDI, a polyester polyol produced by reacting a C36 dimerized fatty acid (“dimer acid”) with 1,6-hexanediol and a chain extender mixture consisting of 1,12-dodecanediol and 2-butyl,2-ethyl propanediol or  1,4-cyclohexanedimethanol (all preferred). Hardblock content in the examples is between 25 and about 45% resulting in a shore A hardness range of about 75 to 95. No thermal data are given.
While this is no doubt an interesting material, I expect this to be a single phase glass with a relatively low Tg and therefore less useful for structural applications.

Example of a C36 dimer acid

Example of a C36 dimer acid

 

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by Gerhard Bleys on August 11, 2014  •  Permalink
Posted in Elastomers, Polyols, Thermoplastics
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Posted by Gerhard Bleys on August 11, 2014

https://purpatents.com/2014/08/11/hydrophobic-and-clear-thermoplastic-polyurethane/

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

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by Gerhard Bleys on August 4, 2014  •  Permalink
Posted in Elastomers, Polyols
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Posted by Gerhard Bleys on August 4, 2014

https://purpatents.com/2014/08/04/hydrolysis-resistant-polyester-polyurethane/

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