PCM Containing PU Gels

Title: Temperature Regulating Polyurethane Gels

Number/Link: US2017/0210961

Applicant/Assignee: Technogel

Publication Date: 27 july 2017

“Gist”: Fatty acid ester PCMs are incorporated into Technogel-type gels without encapsulation

Why it is interesting: Polyurethane gels have been discussed before in this blog. The current invention is about “Technogel-type”  gels, made at low NCO-index and high functionality, that contain phase change materials (PCMs). The PCMs are esters of fatty acids that can be blended in molten state with the low EO polyol to form a clear solution, which is then reacted with isocyanate to form the gel. Despite not being encapsulated or forming a separate phase, the PCMs can reversibly melt and crsytallize while in the fluid phase of the gel. In the examples blends of lauryl laurate (C12-C12) and myristyl myristate (C14-C14) are used as PCM such that the phase change temperature is about 22-38°C.  The gels are said to be useful for ‘close to body’ comfort applications especially for use in matresses to improve sleeping comfort.

Lauryl laurate

 

Formic Acid Blown EPIC Foams

Patent Title: ISOCYANATE-BASED TEMPERATURE-RESISTANT FOAMS WITH HIGH FLAME RESISTANCE

 Number/Link: WO2016/131874

Applicant/Assignee: BASF, Covestro

Publication date: 25-08-2016

Gist”:  One shot rigid isocyanate-epoxy foams blown with formic acid

Why it is interesting: This is the first in a series of (at least) 3 patent applications apparently resulting from a cooperation between BASF and Covestro on epoxy-isocyanate (“EPIC”) foams.  The other applications are WO2016/131878 and WO2016/131880 published on the same date. More publications may follow.
The current invention is about temperature-resistant foams with reportedly very high mechanical properties prepared form a one-shot system comprising a (pref.) high functional MDI, a (pref.) bisphenol-A or bisphenol-F polyglycidylether, at least one reactive amine catalyst and a blowing agent comprising formic acid. The ratio of iso to epoxy groups is (pref.) 3:1 to 15:1. The resulting materials are post-cured at 200°C. The foams contain no, or very little, urethane or urea groups and are said to be especially useful in laminates a.o.  In the examples foams with densities of 25-35 kg/m³ with a thermal conductivity as low as 20 mW/mK are shown.

Bisphenol-F diglycidylether

Bisphenol-F diglycidylether

Novel Polyurethane Gels

Patent Title: POLYURETHANE BASED GEL COMPOSITION

 Number/Link: W016/036786

Applicant/Assignee: Dow

Publication date: 10-03-2016

Gist”: PU gels are made from MDI prepolymer, high EO polyol and some diamine at low NCO index.

Why it is interesting: Polyurethane gels are well known and are sometimes used in comfort cushioning as layers or dispersed as particles in e.g. viscoelastic matresses. According to this invention plasticizer-free gels can be made by reacting a slightly branched, low NCO prepolymer ( based on 2,4′ and 4,4′ MDI and a high EO polyol), with a large amount of high EO polyol (triol or higher) and some amine-ended low mole-weight diol.
Although the material is said to be ‘plasticizer-free’not all of the polyol will be reacted at low NCO index.  However, because of its high polarity, the unreacted polyol will probably not leach.

A Polyurethane Gel

A Polyurethane Gel

Aerogels from Urethane-Acrylate Star Monomers

Title: FLEXIBLE TO RIGID NANOPOROUS POLYURETHANE-ACRYLATE (PUAC) TYPE MATERIALS FOR STRUCTURAL AND THERMAL INSULATION APPLICATIONS

 Number/Link:US2015/0266983

Applicant/Assignee: University of Missouri

Publication date: 24-09-2015

Gist”: A trifunctional acrylate-ended urethane monomer is polymerized in solvent and supercritically dried

Why it is interesting: Research related to nanoporous materials has been gaining significant momentum in recent years and both inorganic (usually silica-based) and organic (e.g resorcinol-formaldehyde or polyurethane -based) aerogels are increasingly being used especially for thermal insulation applications. The current invention relates to hybrid PU-AC aerogels prepared from acrylate functional “star” monomers. The monomers are made by reacting a tris(isocyanatoaryl)methane with one or more hydroxyacrylates in a suitable solvent.  The monomer is then radically polymerized and the resulting ‘wet’ gel is supercritically dried into an aerogel. In the examples tris(4-isocyanatophenyl)methane is reacted with 2-hydroxyethylacrylate in ethyl acetate. The monomer solution is polymerized by heating with a radical initiator and the resulting gel is then dried using acetone and supercritical CO2.  The resulting aerogels have a density ranging from about 135 to 650 kg/m³ with a porosity bewteen 90 and 50% (v/v).  The lower density aerogels are flexible and have a thermal conductivity of about 40 mW/m.K.

Star monomer according to the invention

Star monomer according to the invention

PU Rigid Foams with very Small Cell Size

Title: RIGID POLYURETHANE FOAM HAVING A SMALL CELL SIZE

 Number/Link: WO2015/109488

Applicant/Assignee: Dow

Publication date: 30-07-2015

Gist”: Rigid foams are blown with CO2 under pressure

Why it is interesting: It is known that the thermal conductivity of conventional rigid polyurethane foams can be most efficiently improved by reducing the conductivity contribution of the gas present in the foam cells. This, in turn, can be achieved by reducing the gas pressure, by using ‘heavy’ blowing agents or by reducing the average cell size.  The current application discloses rigid PU foams having cell sizes small enough to achieve a thermal conductivity of less than 16 mW/m.K without the need for a strong vacuum or special blowing agents. This is achieved by first saturating the polyol formulation with CO2 under pressure, then adding the isocyanate and increasing the pressure for a set amount of time and finally releasing the pressure to allow the material to expand. Examples are given using a pressure of 7 MPa at 40°C for 30 minutes to saturate the polyol, and a pressure of 10 MPa for up to about 10 minutes after addition of the isocyanate.  Foams with average cell sizes of 8 to 70 μm and porosities of up to 90% are obtained at densities of about 250 to about 300 kg/m³.  Oddly enough no thermal conductivity (λ) values are given.

Rigid polyurethane insulation foams (Wikimedia)

Rigid polyurethane insulation foams (Wikimedia)