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

UV Resistant Viscoelastic Foams

Patent Title: POLYURETHANE PRODUCT WITH SULFUR-CONTAINING POLYOL

 Number/Link: WO2018/111806

Applicant/Assignee:  Dow

Publication date: 21 June 2018

Gist”: VE foams using S-containing polyether polyols

Why it is interesting: According to this invention sulfur containing polyols improve the UV resistance of polyurethane materials.  It is believed that sulfur acts as a UV absorber incorporated into the polymer, thereby reducing the need for additives such as antioxidants.  In the examples an S-containing polyether diol is prepared by reacting 2,2′-thiodiethanol with propyleneoxide up to an OH value of  188 mg KOH/g. The diol is then used in an amount of 5 to 15% on the total polyol blend to prepare low resilience flexible foams showing an improved UV resistance.

 

TDE

2,2′-thiodiethanol