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

 

Flexible PU Foams Containing Latent Aldehydes

Patent Title: IMPROVEMENTS RELATING TO POLYURETHANES

 Number/Link: WO2017/001543

Applicant/Assignee: Shell

Publication date: 5 january 2017

Gist”: Flex foams from polyether polyols containing latent aldehydes show improved compression set

Why it is interesting: Aldehydes are a by-product of the alkylene oxide production. These aldehydes need to be removed before the alkylene oxide can be used in the manufacture of polyether polyols because even minor amounts of these impurities are considered undesirable and detrimental for polyol and foam properties. According to this invention, omitting the extra purification step of the alkylene oxide results in polyols with a certain amount of free- and latent aldehydes.  (‘latent aldehyde’ being an aldehyde incorporated in the polyether polyol with a labile bond). After removal of the free aldehyde, the polyols with (pref) >150ppm latent aldehydes (mostly propionaldehyde and acetaldehyde) can be used in the preparation of flexible foam with improved wet and dry compression set properties. While the examples indeed show some (but not a dramatic) improvement of compression set, no mention is made of eventual release of the aldehydes in the atmosphere, which (in my opinion) is a much bigger problem than compression set.

Propionaldehyde

Propionaldehyde

Polyurethane Foams with Reduced Acetaldehyde Emissions

Patent Title: POLYURETHANES WITH REDUCED ALDEHYDE EMISSION

 Number/Link: WO2015/189095

Applicant/Assignee: BASF

Publication date: 17-12-2015

Gist”: A polymer with pending -O-NH2 groups is used as additive

Why it is interesting: The reduction of VOC emissions, especially emissions of aldehydes from PU foams, remains an important topic of research. A number of solutions have been proposed, for example the use of polyamines as scavengers as discussed before. There still appears to be a need for improvement however, especially for the reduction of acetaldehyde emissions. According to this invention acetaldehyde emissions can be reduced by using a relatively high mole-weight polymer with pending aminooxy groups as an additive during foaming. In an example a copolymer of 4-aminooxymethylstyrene and methacrylic acid with a Mn of about 15,000 is used as an additive.

Aminooxymethylstyrene

4-aminooxymethylstyrene