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

Tack-Free Polythiourethane Gels

Patent Title: SOFT ISOCYANATE-CROSSLINKED POLYMER SUBSTANCE AND ASSOCIATED PRODUCTS

 Number/Link: WO2017/054797 (German)

Applicant/Assignee: Technogel

Publication date: 6-april-2017

Gist”: Tack-free polyurethane gels are made from polythiols

Why it is interesting: Very soft polyurethane elastomers or “gels” can be made using high functionality isocyanate and monols (as co-invented by myself – e.g. EP1389222 ) or by reacting a high functionality polyol/siocyanate system at low isocyanate-index (as invented by Bayer – later spun off as Technogel).  PU gels are useful as shock dampers, gaskets and cushions but are always tacky and need to be covered or wrapped, which changes their damping and hardness characteristics. According to this invention tack-free gels without the need for covering can be produced by using polythiols instead of polyols, resulting in poly(thiolurethanes) instead of polyurethanes. This is interesting and surprising and I wonder if it would work with the monol-gels as well.

thiolurethane

Thiolurethane linkage

In Situ Reticulated Viscoelastic Foams

Patent Title: VISCOELASTIC AND RETICULATED POLYURETHANE FOAM AND THE PREPARATION THEREOF

 Number/Link: WO2016/198433

Applicant/Assignee: Coverstro

Publication date: 15-dec-2016

Gist”: Composition of 3 semi-miscible polyols and a surfactant

Why it is interesting: This case claims a polyol composition for the preparation of a viscoelastic, reticulated foam without the need for a separate reticulation step. The composition consists of (at least) three polyols and a surfactant:  a low mole-weight all-PO ‘rigid’ triol, a conventional flexible polyol, a high- or all-EO polyol and some off-the-shelf silicone surfactant.  The composition is foamed with water and polymeric MDI or a polymeric MDI/TDI mixture. This is a well-known composition and it is hard to see why this should result in a reticulated foam – unless maybe in some fine-tuned cases.  Apart from the ball rebound being less than 15% the claims do not mention any parameters related to reticulated foam (such as airflow). It is doubtful (in my opinion) that this will get granted.

Cell structure of a reticulated foam

Cell structure of a reticulated foam

Polyrotaxanes in Flexible Foams

Patent Title: POLYOL COMPOSITION FOR PRODUCING FLEXIBLE POLYURETHANE FOAM..

 Number/Link: US20160304689

Applicant/Assignee: Toyo Tire & Rubber

Publication date: 20-10-2016

Gist”: Polyrotaxanes in PU foam reduces ‘wobble’ when used in car seats

Why it is interesting: The use of polyrotaxanes in polyurethanes is not new and has been discussed before in this blog.  According to the current invention polyrotaxanes with OH-functional rings can be incorporated in flexible foams, where they are said to reduce tensile stress while having little impact on compressive properties. When these foams are used in (e.g.) vehicle seats that are subject to low frequency sideways vibrations, they should reduce the sense of “wobble” of the occupants. The theory is that under tension the rings slide along the axis molecule equalizing stresses. In the examples polyrotaxanes with 11000 to 20000 molecular weight PEG axis molecules are used with cyclodextrin rings having an OHv of 43 to 85.

Polyrotaxane-crosllinked polyurethane under stress (schematic)

Polyrotaxane-crosslinked polyurethane under stress (schematic)

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)