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

 

 

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

Green Tea Memory Foam

Patent Title: Foam with Green Tea Additive for Foam Mattresses, Pillows and Cushions

 Number/Link: US2016/0270549

Applicant/Assignee: Zinus

Publication date: 22-09-2016

Gist”: Green Tea is added to memory foam formulation

Why it is interesting: Powdered leaves of the Green Tea plant (Camellia sinensis) are added to memory foam formulations in an amount of less than 2% (w/w) on the total composition.  The Green Tea is said to kill bacteria, mites and molds and reduce the smell of the foam when used in pillows and mattresses for example. Since tea leaves are also claimed to “brighten eyesight, refresh the brain and resist radiation” it’s hard to know if the claim is true. If it doesn’t work it won’t hurt I guess.

Cammelia sinensis (Wikipedia)

Camellia sinensis (Wikipedia)

 

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

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