Scorch-Proof Polyurethane Foams

Patent Title:  LOW EMISSIONS SCORCH INHIBITOR FOR POLYURETHANE FOAM

 Number/Link: WO2018/064521

Applicant/Assignee:  Vanderbilt Chemicals

Publication date: 5 April 2018

Gist”: A synergistic mixture of antioxidants prevents scorch

Why it is interesting: “Scorch” is a discolouration of the center of (especially low-density flexible) polyurethane slabstock foams as a consequence of excessive heat build-up during production. It is believed to be the result of free-radical reactions of foaming components and additives, like the dimerisation of BHT – a common antioxidant. According to this invention the combination of three to (optionally) 5 specific antioxidants show an unexpected synergy towards prevention of scorch. The inventive composition consists of 2,2,4-trimethyl-1,2-dihydroquinoline, a lactone (e.g. 3-alkyl- benzofurane-2-one), a phenolic compound (e.g. an alkylated monophenol) and optionally a tocopherol (a vitamine E-type phenolic compound) and a phosphite compound.  The composition is said to have the added advantage of showing low volatile chemical emissions.

quinoline

2,2,4-trimethyl-1,2-dihydroquinoline

PU Flexible Foams with Reduced Acetaldehyde Emissions

Title: METHOD FOR THE REDUCTION OF ALDEHYDE EMISSION IN POLYURETHANE FOAM

Number/Link: WO2017/134296

Applicant/Assignee: Huntsman

Publication Date: 10 August 2017

“Gist”: Cyanoacetamide is used as aldehyde scavenger

Why it is interesting: Reduction of aldehyde emissions from (especially flexible) polyurethane foams remains an important issue and has already been discussed a number of times on this blog. According to this case the use of (pref) 0.05 to 0.5 pbw of cyanoacetamide in a flexible foam formulation will reduce the emission of formaldehyde, acetaldehyde, propionaldehyde, and possibly of higher aldehydes as well.
While an interesting compound, the use of cyanoacetamide in polyurethanes is not new and the effect is hardly surprising.

Cyanoacetamide

 

Polycarbonate PU Foams with Reduced VOC Emissions

Title: POLYURETHANE FOAMS BASED ON POLYETHER CARBONATE POLYOLS

Number/Link: WO2017/085201 (German)

Applicant/Assignee: Covestro

Publication Date: 26-may-2017

“Gist”: Use of urea reduces the formation of propylenecarbonate from polycarbonate polyols

Why it is interesting: Covestry is betting heavily on polyethercarbonate polyols for use in polyurethane foams, using the carbon-negative footprint as a selling point. The use of polyethercarbonate polyols in PU foams can, however, result in the formation of propylenecarbonate resulting from a retro reaction promoted by conventional amine catalysts. Propylenecarbonate will contribute to the total VOC emissions of foams and other materials. According to this invention, the retro reaction can -surprisingly- be prevented or reduced by using urea or urea-derivatives in the foam formulation. In the examples urea and dimethylaminopropylurea are used together with a tin catalyst,  polyethercarbonate polyols and TDI to produce flexible foams with reduced propylenecarbonate content.

Propylenecarbonate