Translucent Rigid Foams

Patent Title: TRANSLUCENT POLYURETHANE FOAMS

 Number/Link: WO2018/178139  WO2018/177987  (German)

Applicant/Assignee:  Covestro

Publication date: 4 October 2018

Gist”: Rigid foam formulation is mixed without air to delay nucleation

Why it is interesting: The invention is about translucent rigid foams which are said to be useful as wall and roof elements such as light strips, light domes and the like.  The foams are based on (pref.) trimerized aliphatic diisocyanates and are blown with water.  The composition is degassed and then mixed without inclusion of air to delay nucleation. The resulting foams have a course cell structure and thick cell struts which apparently allows light to pass through.

 

Desmodur N3900

Asymmetric trimer of HDI (iminooxadiazinedione)

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)

 

Carbamate Blown Rigid Foams

Patent Title: A METHOD FOR PRODUCING AN OPEN CELL RIGID POLYURETHANE FOAM

 Number/Link: WO2018096101  WO2018096102

Applicant/Assignee:  Covestro

Publication date: 31 may 2018

Gist”: An open cell rigid foam is prepared using an amine-CO2 adduct and water as blowing agents

Why it is interesting: According to this invention an open cell rigid spray foam can be prepared from a conventional rigid foam formulation and a blowing agent consisting of 4-12 parts (pref.) on 100 parts of polyol of an adduct of a primary or secondary amine and carbon dioxide, together with 15 to 50 parts of water.  The properties of the resulting open cell, low density foam are said to be largely independent of ambient conditions and spray thickness. The foams are useful for thermal insulation applications in construction.

carbamate

Carbamate of N,N-dimethylaminopropylamine

 

PIR-Oxazolidone Foams from Natural Oils

Patent Title: METHOD FOR MANUFACTURING A POLYURETHANE-MODIFIED FOAM, FOAM OBTAINED, AND USES

Number/Link: US2018/0030196

Applicant/Assignee:  Soprema et al.

Publication date: 1 February 2018

Gist”: Unsaturated natural oils are epoxidized and reacted with an excess of isocyanate in the presence of a blowing agent.

Why it is interesting: Conventionally natural oils are incorporated into polyurethanes by first converting them to polyols (“NOPs”) by hydroformylation or epoxidation and ring opening and then reacting the NOPs with isocyanates. According to this invention the natural oils (preferably extracted from microalgae) are epoxidized and then mixed and heated with a (e.g. 3:1) excess of isocyanate (e.g. polymeric MDI) in the presence of a blowing agent (e.g. isopentane). It is said that oxazolidone rings from the isocyanate-epoxy reaction will form at the same time as isocyanurate rings and homopolymerized epoxides. The foams are said to be useful for thermal insulation applications.

oxazolidone

Formation of oxazolidone rings according to the invention

Isocyanate-Free Polyaminal-Polyurethane Foams

Patent Title: SYSTEM FOR DIMENSIONALLY STABLE ISOCYANATE-FREE POLYURETHANE FOAM

 Number/Link: WO2018/005142

Applicant/Assignee:  Dow

Publication date: 4 January 2018

Gist”: Polyaldehydes are reacted with polycarbamates in the presence of an acid catalyst, a metal oxide powder and a blowing agent.

Why it is interesting: According to this invention hydrolytically-stable foams can be prepared from a low molecular weight difunctional aldehyde and a polycarbamate with a functionality of about 3.5 to 4 and an equivalent weight of about 200 to 300, in the presence of a blowing agent and a protic acid as catalyst. Surprisingly the foams are rendered hydrolytically stable by the incorporation of a metal oxide powder with a specific particle size. In the examples polycarbamates are prepared by capping high functionality polyols with methylcarbamate and are then reacted with 1,4-cyclohexanedicarboxaldehyde together with p-toluensulfonic acid as catalyst, HFC245fa as blowing agent and MgO powder. The foams show densities of 130-170 kg/m³ and are said to be useful as sealants.

CHDA

Cyclohexanedicarbaldehyde