Polyurethane for Oil Well Refracking

Patent Title: METHODS AND MATERIALS FOR REFRACTURING A PARTIALLY DEPLETED OIL AND GAS WELL

Number/Link: US2018/0346786

Applicant/Assignee:  Covestro

Publication Date: 6 December 2018

“Gist”: Use of low-reactive, low-viscosity PU systems for oil well sealing

Why it is interesting: It is known that partially depleted fracking wells can be “re-fractured” to increase production. Prior to this operation former perforations in the well casing need to be sealed to prevent furthering of existing fractures, by using a chemical “diverting agent”.  According to this invention, the diverting agent can be a polyurethane system with a long potlife and relatively low viscosity, which is prepared from an unblocked hexamethylene diisocyanate and a polypropyleneoxide triol which is miscible with the isocyanate. In the examples an allophanate-modified HDI is used together with a 450-molecular weight PO triol and a delayed-action tert amine catalyst. The system does not de-mix and has a gel time ranging from 30 to more than 1000 minutes.

refracking

Sealing of fracking well

 

 

m-Xylylene Diisocyanate for Polythiourethanes

 

Patent Title: ISOCYANATE COMPOSITION FOR OPTICAL LENSES AND PROCESS FOR PREPARING THE SAME

 Number/Link: US2018/0334531

Applicant/Assignee:  SKC

Publication date: 22 November 2018

Gist”:  m-XDI is prepared from purified m-xylylene diamine and used for improved optical materials

Why it is interesting: Polythiourethanes have a high refractive index, a high transparency and a relatively high impact resistance and their use in optical lenses is well known. In this invention, polythiourethanes are prepared by using ‘pure’ (i.e. 99 to 100%) m-XDI as the isocyanate. The m-XDI is prepared from m-xylylene diamine from which impurities (esp. o-XDA, p-XDA and monoamines) are removed by distillation or crystallization.  Polythiourethanes prepared from 100% m-XDI are said to show improved optical properties such as refractive index, transparency, dispersion (Abbe number), yellowness, cloudiness etc.

XDI

Polyurethanes Emission Control – EBook

Emissions of volatile organic compounds (VOC) from polyurethane systems and materials can contribute to safety, health and environmental issues and are subject to ever more stringent laws and regulations.

This report reviews the different strategies and technologies to reduce or eliminate emissions from polyurethane systems as disclosed in the recent patent literature.
The following groups of compounds are discussed:

  • Monomeric isocyanates
  • Aldehydes
  • Amines
  • Silicones
  • Antioxidants
  • Flame retardants
  • Cyclic oligomers
  • “Odours”

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