Classic PU Patent of the Month: The First Polyether Foams (1951)

Title: Verfahren zur Herstellung von Kunststoffen

 Number/Link: DE974371 (German)

Applicant/Assignee: Bayer AG

Publication date: 12-08-1960

Gist”: A prepolymer from a polyether polyol and an excess of isocyanate is reacted with water to produce an elastomeric  foam.

Why it is interesting: This patent specifies the first polyether prepolymers and polyether  foams as invented by Otto Bayer and co-workers.  In the examples an all-EO, 4000 MW triol, prepared from trimethylolpropane and  ethylene oxide is reacted with a surplus of TDI resulting in a 3.2% NCO prepolymer.  This prepolymer is reacted with water to form either elastomeric films or elastomeric (flexible) foams. There are only two claims, the first covering  polyether prepolymers, the second covering both “one-shot” and “full prepolymer” water-blown polyether foams:

PATENTANSPRÜCHE:

1. Verfahren zur Herstellung von Kunststoffen,
dadurch gekennzeichnet, daβ Polyglykolather mit
einem Molekulargewicht von mindestens 500 und
mindestens zwei endstandigen Hydroxylgruppen
mit einem Übersehuβ über die berechnete Menge
an polyfunktionellen aliphatischen oder aromatischen
Isocyanaten und die erhaltenen Polyglykolätherisocyanate
mit Verbindungen mit reaktionsfahigem Wasserstoff
umgesetzt werden.

2. Ausführungsform des Verfahrens nach Anspruch
1, insbesondere zur Herstellung von Schaumstoffen,
dadurch gekennzeichnet, daβ als Verbindung
mit reaktionsfahigem Wasserstoff Wasser verwendet
wird und die Umsetzung mit Wasser gleichzeitig
mit der oder anschlieβend an die Umsetzung
der Polyglykolather und polyfunktionellen
Isocyanate erfolgt.

Dr. Otto Bayer

Dr. Otto Bayer

Polyurethane “Combination Foam”: a TPU/PU Composite

Title: KOMBINATIONSSCHAUM

 Number/Link:  WO2014/023794   (German)

Applicant/Assignee: BASF

Publication date: 13-02-2014

Gist”: Foamed TPU particles are embedded in a foamed elastomer of the same chemical composition to improve mechanical properties.

Why it is interesting: Foamed, closed-cell TPU particles are incorporated in a foamed, open-cell PU matrix which has a higher density and is produced from essentially the same chemicals, resulting in perfect compatibility and adhesion between the two components.  In the examples 30-40 % (w/w) of expanded TPU particles with a bulk density (“Shüttdichte”) of 89 kg/m³ are incorporated in an elastomer with a density of 200-300 kg/m³. Size of the TPU particles is not given but the preferred size range is 1mm to 2 cm.

Expanded TPU particles by BASF

Expanded TPU particles by BASF

Classic PU Patent of the Month: “Hypersoft” Flexible Foams (1971)

Title: PROCESS FOR OBTAINING POLYURETHANE FOAMS

 Number/Link: GB1381925

Applicant/Assignee: PECHINEY UGINE KUHLMANN

Publication date: 29-01-1975   (priority FR – 1971)

Gist”: Very soft hydrophilic flexible foam is made from TDI and a combination of a high EO polyol and a ‘conventional’ (hot cure) polyol.

Why it is interesting: Very soft – so called “hypersoft” – foams were prepared form TDI 80/20 and  a mixture of polyols consisting of a random 75% EO -25% PO triol and a block 90% PO – 10% EO triol in a ratio of 85:15. (about).  The foams were all-water blown and had densities of below 30 kg/m³, which was exceptional for the time.

Pechiney Logo.

Pechiney Logo.

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