Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – From carboxylic acid or derivative thereof
Reexamination Certificate
2006-06-13
2006-06-13
Hightower, P. Hampton (Department: 1711)
Synthetic resins or natural rubbers -- part of the class 520 ser
Synthetic resins
From carboxylic acid or derivative thereof
C528S310000, C528S335000, C528S336000, C528S337000, C528S339000, C528S340000, C528S353000, C528S342000, C528S348000
Reexamination Certificate
active
07060782
ABSTRACT:
A process for the production of high molecular weight polybenzimidazole by one: providing a first reaction vessel; charging the reaction vessel with at least one aromatic hydrocarbon tetraamine, and a heterocylic ring making up the dicarboxylic component; heating the reactants under agitation in a substantially oxygen-free atmosphere with agitation until the agitator torque is about 1.5 times the torque before a rise in viscosity begins; terminating the agitation while continuing to heat the reaction mixture to about 230° C. while allowing the reaction mass to foam; cooling the reaction mass to a friable foamed mass; crushing the friable foamed mass to obtain a ground prepolymer; and two: providing a second reaction vessel, the second reaction vessel being a high intensity reaction vessel; transferring the ground prepolymer to the second reaction vessel; heating the ground prepolymer under agitation to over 315° C. at atmospheric pressure for a time of about 90 minutes.
REFERENCES:
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patent: 2006/0004181 (2006-01-01), Dawkins et al.
patent: 2006/0004182 (2006-01-01), Dawkins et al.
Baker J. Dean
Dawkins Bobby G.
Joiner Rita H.
Hammer & Hanf, P.C.
Hampton Hightower P.
PBI Performance Products, Inc.
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