Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – From reactant having at least one -n=c=x group as well as...
Reexamination Certificate
2006-05-02
2006-05-02
Truong, Duc (Department: 1711)
Synthetic resins or natural rubbers -- part of the class 520 ser
Synthetic resins
From reactant having at least one -n=c=x group as well as...
C528S052000, C528S085000, C528S269000, C560S347000, C560S358000, C560S359000
Reexamination Certificate
active
07038002
ABSTRACT:
A fraction of diisocyanates of the diphenylmethane series containing at least 95 wt. % binuclear methylenediphenyl diisocyanate is obtained bya) reacting aniline and formaldehyde in the presence of an acid catalyst to produce diamines and polyamines of the diphenylmethane series containing binuclear methylenediphenyl diamine,b) phosgenating the diamines and polyamines produced in a), optionally in the presence of a solvent, to produce a crude diisocyanate and polyisocyanate, andc) separating a fraction containing at least 95 wt. % binuclear methylenediphenyl diisocyanate with a 4,4′-MDI content of over 60 wt. %, a 2,4′-MDI content of 4 to 35 wt. % and a 2,2′-MDI content of 0.01 to 10 wt. %, relative to the mass of the fraction, and a maximum of 20 ppm phenyl isocyanate and optionally a maximum of 50 ppm solvent from the crude diisocyanate and polyisocyanate produced in b) in a single distillation step with optional upstream and/or downstream separation of low-boiling components.
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Manfred Stepanski and Peter Faessler, “New Hybrid Process for Purification and Separation of MDI Isomers”, pp. 594-600.
Echterhoff Ralf
Liman Ulrich
Pirkl Hans-Georg
Vieler Robert
Bayer Materialscience AG
Gil Joseph C.
Truong Duc
Whalen Lyndanne M.
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