All posts in category dispersions

Preventing Ostwald Ripening in Rigid PU Foams

Title: PRODUCTION OF FINE CELL FOAMS USING A CELL AGING INHIBITOR

Number/Link: WO2017093058 (German)

Applicant/Assignee: Evonik

Publication Date: 8 June 2017

“Gist”: Perfluorinated hydrocabons reduce Ostwald ripening in PU foam formulations

Why it is interesting: Polymeric foams form by nucleation and growth of gass bubbles in the reacting mixture followed by (or simultaneous with) ageing of the bubbles through coalesence and Ostwald ripening, i.e. the growth of larger bubbles at the expense of smaller bubbles. Ostwald ripening ultimately results in fewer and larger cells, which has a negative effect on the thermal insulation properties of rigid foams. According to this invention the ripening effect can be prevented or reduced by incorporating in the foam formulation an “Ostwald hydrophobe”, i.e. a highly hydrophobic liquid which is largely immiscible with the reacting mixture. Examples of such liquids are perfluorinated hydrocabons with a boiling point of less than 150°C, e.g. perfluoropentane, perfluorocyclohexane and perfluoroisohexene (used in the examples).

Perfluorocyclohexane

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

TPU-Silicone TPVs

Patent Title: THERMOPLASTIC POLYURETHANE COMPOSITE MATERIAL COMPOSITION, THERMOPLASTIC POLYURETHANE COMPOSITE MATERIAL AND MANUFACTURING METHOD THEREOF, SHOE MATERIAL AND WEARABLE APPARATUS

Number/Link: US2017 /0015825

Applicant/Assignee: Evermore Chem. Ind.

Publication date: 19-jan-2017

“Gist”: A blend of TPU and unsaturated silicone gum is dynamically vulcanized

Why it is interesting: A thermoplastic polyurethane is blended (in a kneader) with 1 to 5% w/w of double-unsaturated silicone rubber gum. The blend is then dynamically vulcanized by extruding (and pelletizing) it together with a peroxide curing agent like e.g. 1,3-bis-(t-butylperoxyisopropyl)benzene. The resulting thermoplastic is said to have improved slip resistance without reducing the TPU properties like abrasion resitance and is therefore said to be especially useful for the production of shoe-soles. It is ‘contemplated’ that the resulting material is a semi-IPN, but (i.m.o.) it is more likely that a seperate crosslinked silicone phase -and therefore a thermoplastic vulcanizate (TPV)- is formed.

1,3-bis-(t-butylperoxyisopropyl)benzene

Innovation in Polyurethanes

All posts in category dispersions

Preventing Ostwald Ripening in Rigid PU Foams

Aerogels from Isocyanates and Epoxies

TPU-Silicone TPVs

Pages

Categories

Search

Follow this blog via email

Follow Innovation in PU on Twitter