Open Microcellular Rigid Foams

Patent Title: POLYURETHANE FOAM AND PROCESS FOR PRODUCING SAME

 Number/Link: WO 2018/162372 (German)

Applicant/Assignee:  Covestro

Publication date: 13 September 2018

Gist”: Rigid foam formulation is blown with supercritical carbondioxide

Why it is interesting: Open-celled rigid polyurethane foams are well known and used in vacuum insulation panels. Theoretically the best thermal insulation is obtained with the smallest cell size. According to this invention microcellular rigid foams with a homogeneous cell structure, more than 90% open cells and an average cell diameter of less than 50μm can be prepared by using a rigid foam formulation containing a cellopener and supercritical carbondioxide and allowing it to react and expand in a closed mould. In an example a rigid foam is produced with a density of 67kg/m³, open cell content of 95% and average cell diameter of 17μm.

CO2_phase_diagram

Carbon dioxide (P,T) phase diagram (Wikipedia)

 

PCM-Containing Viscoelastic Foams

Patent Title: VISCOELASTIC POLYURETHANE FOAM WITH COATING

Number/Link: WO2017/210439

Applicant/Assignee: Dow

Publication date: 7 December 2017

“Gist”: Open-celled visco-foam is impregnated with an aqueous dispersant composition containing a phase change material

Why it is interesting: According to Dow, open-celled viscoelastic polyurethane foams can be prepared by using a acid-modified polyolefin latex cellopener, as discussed before in this blog. In the current invention these open-celled foams are impregnated with an aqueous composition comprising an ionomer (a sodium salt of a maleic anhydride copolymer) and a microencapsulated PCM. The composition is said to ‘coat’ the cell struts with PCM and increase the comfort properties of the foam.
I wonder if with this process enough PCM can be in introduced to have a noticeable effect.

bluewave

Dow’s proprietary BLUEWAVE dispersion process is used to prepare the cellopening latex

TPU Foams

Title: POLYURETHANE FOAMS AND METHOD FOR PRODUCING SAME

Number/Link: US2017/0174818

Applicant/Assignee: Lubrizol

Publication Date: 22-june-2016 (PCT oct. 2015)

“Gist”: TPUs with specific MW and polydispersity are injection moulded together with cellopener and gas in supercritical state

Why it is interesting: The invention relates to injection moulded “flexible foams”, especially useful for footwear applications. Thermoplastic polyurethanes with a Mw of 120,000 to 500,000 and a dispersity index of 1.85 to 2.51 are foamed using a gaseous blowing agent (CO2 or C1 to C6 hydrocarbons etc. ) together with a cellopener (silicone or EO/PO surfactant), such that at least 50% of cells are open.  In the examples the blowing agent is added in supercritical state to the melt before injection moulding. The type of gas used, nor the densities of the foams are mentioned.  Foaming TPU with gas in supercitical has also been file by Nike as discussed before in this blog.

Nike shoe with foamed thermoplastic midsole

 

In Situ Reticulated Viscoelastic Foams

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

 Number/Link: WO2016/198433

Applicant/Assignee: Covestro

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

Improved Cellopening System for Flexible Foams

Title: Process For Producing Flexible Polyurethane Foam Using Natural Oil Polyols

Patent Number & Link: US2013/197114

Applicant/Assignee: Air Products

Publication date: 1-08-2013

Gist”: Use of 2-cyanoacetamide as cellopener together with a dipolar aprotic liquid as “cellopening aide” in moulded flexible foams.

Why it is interesting: The use of compounds with an active (acidic) methylene group like 2-cyanoacetamide as cellopener for flexible foam is known (US6136876) but has some disadvantages like low solubility in polyol and low reproducibility when dissolved in water. The use of these cellopeners together with dipolar aprotic solvents like dimethylsulfoxide (DMSO) or glycols like PEG200 supposedly solves these problems and allows for the use of a lower amount of the cellopener.  In the examples 0.03 pphp of cyanoacetamide is used together with 0.12pphp of DMSO. Strangely claim 1 expressly states the use of at least one NOP (natural oil based polyol) while this does not seem relevant to the invention.

2-cyanoacetamide

2-cyanoacetamide