Breathable TPU Membranes

Patent Title: POROUS THERMOPLASTIC MEMBRANES

 Number/Link: WO2017/178482

Applicant/Assignee:  BASF

Publication date: 19-october-2017

Gist”: Semi-permeable membranes are made by phase inversion of all-hardblock TPU solutions

Why it is interesting: ‘Breathable” membranes show a high resistance to liquid water permeation (LEP) combined with a high water vapour permeability (WDD). According to this invention breathable polyurethane membranes can be prepared by dissolving an all-hardblock thermoplastic polyurethane in a polar, aprotic solvent (like N-methyl pyrrolidone) together with a water soluble compound, casting a film and coagulating the film with water. In the examples diisocyanates (MDI, TDI and HDI) are stoichiometrically reacted with chain extenders (MEG, BDO and HDO).  The resulting materials were schredded and dissolved in NMP together with some glycerol. 150 μm thick films were cast on glass and coagulated in water, resulting in membranes with an average pore size ranging between 4 and 500 nm.  The membranes are said to be useful to make breathable fabrics for outdoor wear e.g. (“Gore Tex” (TM) – type materials)

N-methyl-2-pyrrolidone

 

 

 

 

Spirocyclic Chain Extenders in TPU

Patent Title: THERMOPLASTIC POLYURETHANE WITH HIGH HEAT RESISTANCE

 Number/Link: W02016025421  WO2016025423

Applicant/Assignee: Lubrizol

Publication date: 18-02-2016

Gist”: Use of spirocyclic chain extenders increases heat resistance of TPU

Why it is interesting: Both these patent applications are about the use of alkylene-substituted spirocyclic diols to improve the heat resistance of thermoplastic polyurethanes. In the WO..21 case the diol is used together with MDI and a polycarbonate diol resulting in high heat resistance TPU useful e.g for cable and wire coatings.  In the WO..23 case the spirocyclic diol is used together with MDI and a polyether polyol (PEGs) resulting in TPU with high heat resistance and moisture vapour transmission.  The spirocyclic diol used in the examples is 3,9-bis(1,1-dimethyl-2-hydroxyethyl)-2,4,8,10-tetraoxaspiro[5.5]undecane.

3,9-bis(1,1-dimethyl-2-hydroxyethyl)-2,4,8,10-tetraoxaspiro[5.5]undecane

3,9-bis(1,1-dimethyl-2-hydroxyethyl)-2,4,8,10-tetraoxaspiro[5.5]undecane