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)

 

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

 

 

Improved Nanoporous Insulation Materials

Title: AEROGEL-CONTAINING POLYURETHANE COMPOSITE MATERIAL

 Number/Link: WO2013182506 (German)

Applicant/Assignee: BASF

Publication date: 12-12-2013

Gist”: An aqueous dispersion based on an isocyanate and an isocyanate-reactive vinyl polymer is used to bind aerogel particles into an insulation material.

Why it is interesting: Binding (silica) aerogel (or xerogel or cryogel) particles into insulation panels using aqueous polyurethane binders is known.  See e.g. my previous posts on the subject here, here and here. According to this invention both the insulation and processing properties of existing systems can be improved by using an aqueous dispersion of a vinyl polymer containing isocyanate-reactive side groups, together with an emulsifiable isocyanate. The polyvinyl is preferably water-soluble, the side groups being -OH, -SH, -NH2 or -COOH,  a (preferred) example being poyvinylamine with a molecular weight from 10,000 to 500,000. The isocyanate used is preferably a modified HDI or IPDI.  In the examples materials are shown with densities of about 120 kg/m³ and a thermal conductivity of about 16 mW/m.K.

SLENTITE (TM) aerogel-PU insulation panel by BASF

SLENTITE (TM) aerogel-PU insulation panel by BASF