Flexible Foams with Reduced Aldehyde Emissions

Patent Title: POLYURETHANE FOAMS HAVING LOW LEVELS OF ALDEHYDE EMISSIONS

 Number/Link: WO2018/145283

Applicant/Assignee:   Dow

Publication date: 16 August 2018

Gist”: Cyclic 1,3-diketones are used as aldehyde scavengers

Why it is interesting: Aldehyde emissions from flexible polyurethane foams (and many other materials) remain an issue and have been discussed a number of times before in this blog.  The current invention is about the use of cyclic 1,3-diketones as scavengers for both fomaldehyde and acetaldehyde in flexible foam formulations.  Diketones like (e.g.) 5-phenylcyclohexane-1,3-dione, 5,5-dimethylcyclohexane-1,3-dione and 1H-indene-1,3(2H)-dione are blended with the polyol component and react with the aldehydes during foam cure.

DMCHD

5,5-dimethylcyclohexane-1,3-dione

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

Reducing Aldehyde Emissions from Polyurethane Foams

Title: USE OF PENTAETHYLENE HEXAMINE IN THE PRODUCTION OF POLYURETHANE SYSTEMS

 Number/Link: WO2015/071065 (German)

Applicant/Assignee: Evonik

Publication date: 21-05-2015

Gist”: Use of pentaethylenehexamine to reduce aldehyde emissions

Why it is interesting: As mentioned in previous posts, the reduction of formaldehyde and acetaldehyde emissions from polyurethane foams remains a pressing environmental issue. According to this patent application the problem can be solved by adding some (1 pphp in the examples) of pentaethylene hexamine to the polyol formulation. The polyamine will act as a formaldehyde scavenger and has some advantages over the prior art.  In the related case WO2015/071063, the pentaethylene hexamine is first reacted with guanidine chloride before being added to the formulation.

Pentaethylene hexamine

Pentaethylene hexamine