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)

 

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Aerogels from Isocyanates and Epoxies

Patent Title: ORGANIC AEROGELS BASED ON ISOCYANATE AND CYCLIC ETHER POLYMER NETWORKS

 Number/Link: WO2017016755

Applicant/Assignee: Henkel

Publication date: 2-feb-2017

Gist”: Isocyanate and epoxy are reacted in solvent and supercritically dried

Why it is interesting: While most ‘conventional’ aerogels are based on silica, organic aerogels, especially isocyanate-based aerogels, are also well known: polyurethane-, polyurea-, polyamide-, polyimide-, polycarbodiimide- and polyisocyanurate aerogels have all been reported. This invention adds another type of aerogel based on the reaction of isocyanates and cyclic ethers, esp. oxetanes and oxiranes. The isocyanate with a functionality of (pref.) 2 to 3, (e.g. 4,4′-MDI or methylidynetri-p-phenyletriisocyanate) is reacted with a cyclic ether  of (pref.) functionality of 2 to 3, (e.g. N,N-diglycidyl-4-glycidyloxianiline) in a suitable solvent (e.g. DMAc). After washing, the gel is dried with supercritical carbon dioxide. The materials are useful for thermal insulation and are said to have better mechanical properties compared to other organic aerogels.

N,N-Diglycidyl-4-glycidyloxyaniline

N,N-Diglycidyl-4-glycidyloxyaniline

 

 

Insulating Wood-Aerogel Composites

Title: REINFORCED ORGANIC NATURAL FIBER COMPOSITES

 Number/Link: WO2015/144267

Applicant/Assignee: Huntsman

Publication date: 1-10-2015

Gist”: Aerogel particles are incorporated in composite wood boards

Why it is interesting: Composite wood products (OSB, MDF..) are  well known and popular construction materials which are produced by compressing wood fibers (or flakes and the like) together with a binder like e.g. a polymeric MDI. Typically these materials show thermal conductivity values of about 50 mW/m.K at densities of around 200 kg/m³.  According to this invention these insulation values can be significantly improved by incorporating (a large amount of) hydrophobic nanoporous particles and binding the composite with an in-water emulsified isocyanate. In the examples silica aerogel particles and wood fibers are mixed an bonded with an emulsifiable MDI. The amount of particles ranges from about 25 to 50% (w/w) resulting in composites with densities below 200 kg/m³ and insulation values of about 20 to 30 mW/mK.

Medium density fibreboard (MDF).

Medium density fibreboard (MDF).