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

 

 

TPU with Moisture-Controlled Flexibility

Title: THERMOPLASTIC POLYURETHANE MATERIALS FOR FORMING MEDICAL DEVICES

Number/Link: Wo2017/066381

Applicant/Assignee: Becton Dickinson

Publication Date: 20 april 2017

“Gist”: High hardblock TPU, based on side-chain branched chain extenders, softens in water

Why it is interesting: The invention is related to thermoplastic polyurethanes for medical applications especially for intravenous catheters. These catheters need to have a high stiffness when inserted but need to become flexible once in place to prevent injuries. This is accomplished with TPUs based on MDI, PTMEG and either 2,2-dimethyl-1,3-propanediol (neopentylglycol) or 2-methyl-1,3-propanediol (MPdiol) and having a hardblock content of 50 to 75%. The examples show indeed an increased stiffness at ambient conditions and a larger softening when soaked in saline solution compared to TPU produced with a linear chain extender. It is however not mentioned which linear chain extender was used.

Neopentylglycol

High Resiliency Polyurethane Foams

Title: HIGH RESILIENCY POLYURETHANE FOAMS MADE WITH HIGH FUNCTIONALITY, HIGH EQUIVALENT WEIGHT POLYOLS WITH MAINLY SECONDARY HYDROXYL GROUPS

Number/Link: WO2017/062150

Applicant/Assignee: Dow

Publication Date: 13 April 2017

“Gist”: Use of high functionality polyols increases the resilience of flex foams

Why it is interesting:  According to this invention the resilience of flexible PU foams can be increased by using, as part of the polyol composition, a random EO/PO polyether polyol which has an equivalent weight of at least 1500, a functionality of  at least 5, a secondary hydroxyl group content of at least 70%, an unsaturation value of at most 0.01 meq/g and an EO content between 5 and 30%.  In the examples, sorbitol initiated polyols are used in both MDI and TDI-based systems, resulting in ball rebound values of up to 60% at densities of about 30 kg/m³.  As I have shown in the past (US5521226) the same (or arguably an even stronger) effect on resilience can be obtained with other high functionality polyols, indicating that the unsaturation value, primary OH content, EO content and equivalent weight are probably not relevant to the resilience increase.

Sorbitol

TPU with Anti-Biofouling Surface

Patent Title: ANTIFOULING COMPOSITION

 Number/Link: WO2017/007899

Applicant/Assignee: BASF

Publication date: 12-jan-2017

Gist”: TPU containing silicone diol and having microstructured surface

Why it is interesting: Biofouling of surfaces e.g. in the marine environment or of medical implants is a problem.  For example the growth of barnacles on the hulls of vessels, subsea cables, pipes and energy generating structures has a significant economic impact. According to this invention, thermoplastic polyurethane articles with a surface energy of about 20 mN/m and a microstructered surface topography show an improved resistance to biofouling. The TPU is produced by incorporating 5-15% on the total composition of a PDMS diol with a OH value of 15 to 150, and by pressing onto the surface a 3D topology with ‘peaks’ and ‘valleys’ of an order of magnitude of 10μm.

Microstructured surface according to the invention

Microstructured surface according to the invention

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