Polyurethanes with Reduced Aldehyde Emissions

Title: POLYURETHANES HAVING REDUCED ALDEHYDE EMISSION

 Number/Link:WO2015/082316 (German)

Applicant/Assignee: BASF

Publication date: 11-06-2015

Gist”: Use of CH-acidic compounds as aldehyde scavengers

Why it is interesting: Reducing VOC emissions, and especially aldehyde emissions, from polyurethane systems remains an important research topic and has been discussed before on this blog (see e.g.  here and here). To reduce aldehyde emissions, scavenger molecules are used which are often amines or hydrazine compounds.  In this invention however the aldehyde scavenger is a CH-acidic compound of the form R-CH2-R’ in which R and R’ are electron-withdrawing groups. The R-groups can be iso-reactive and the molecule can (preferably) contain more than one acidic CH2 group, like e.g. trimethylolpropane triacetoacetate. Other examples are N,N-dimethylacetoacetamide and dimethyl 1,3-acetonedicarboxylate. The compounds are used in an amount of 0.5 to 1 pphp, are said to have advantages over the prior art like less or no catalytic activity and do not lead to extra emissions.

Trimethylolpropane triacetoacetate

Trimethylolpropane triacetoacetate

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

Reducing aldehyde emissions from flexible foams

Title: POLYURETHANE FOAMS WITH DECREASED ALDEHYDE EMISSIONS, A PROCESS FOR PREPARING THESE FOAMS AND A METHOD FOR DECREASING ALDEHYDE EMISSIONS IN POLYURETHANE FOAMS

 Number/Link: WO2013116092

Applicant/Assignee: Bayer

Publication date: 8-08-2013

Gist”: Use of small amounts of hexamethylenediisocyanate trimer or small amounts of “PHD” polyols result in reduced aldehyde emissions from flex foams.

Why it is interesting: Reduction of VOC emissions and especially emissions of formaldehyde and acetaldehyde are an important issue for the polyurethane flexible foam industry, especially for bedding and automotive applications. This invention teaches two “tricks” to help solve the problem.  To a (preferably) TDI-based flex foam formulation which comprises at least one SAN or PIPA filled polyol, 0.5-3 pbw of trimerized hexamethylene diisocyanate is added on 100 pbw of the isocyanate.  Alternatively 2-3 pbw of PHD polyol is added on 100 pbw of the iso-reactive component. In the art “PHD polyol” usually stands for a polyurea ‘filled’ polyol (polyharnstoff dispersion), but in this case it stands for polyhydrazodicarnbonamide filled polyols. These PHD polyols are prepared by reacting a hydrazine with an isocyanate (pref TDI80) in a base polyol, so they are actually a subset of ‘conventional’ PHD dispersions.  The patent application is a bit confusing in this respect.

Hydroazodicarbonamide

Hydrazodicarbonamide

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