Process for producing 2, 3, 3′, 4′,-biphenyltetracarboxylic dianhydride
AssigneeUbe Industries, Ltd.
InventorsKenichiro Sasaki, Tatsushi Nakayama
Life of this patent
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Abstract
2,3,3′,4′-biphenyltetracarboxylic acid is heat-dehydrated in a molten state at a temperature not lower than 200° C. in a flow of an inert gas in a reactor 10 having at least one reaction vessel 11 by stirring the molten material to produce 2,3,3′,4′-biphenyltetracarboxylic dianhydride. Thus obtained 2,3,3′,4′-biphenyltetracarboxylic dianhydride in the molten state is subsequently cooled and solidified in an inert gas or dry air, or cooled and solidified in the ambient air at a temperature of 40° C. or lower or 100° C. or higher.
Claims16
A process for producing 2,3,3′,4′-biphenyltetracarboxylic dianhydride, comprising a dehydration step of:
- heat-dehydrating 2,3,3′,4′-biphenyltetracarboxylic acid in a molten state at a temperature not lower than 200° C. in a flow of an inert gas in a reactor having at least one reaction vessel by (i) stirring the molten material, or (ii) in bubbling the molten material by passing the inert gas;
- thereby, producing 2,3,3′,4′-biphenyltetracarboxylic dianhydride.
A process for producing 2,3,3′,4′-biphenyltetracarboxylic dianhydride, comprising:
- cooling and solidifying a molten 2,3,3′,4′-biphenyltetracarboxylic dianhydride in an inert gas or dry air;
- or
- cooling and solidifying a molten 2,3,3′,4′-biphenyltetracarboxylic dianhydride in the ambient air at a temperature of 40° C. or lower or 100° C. or higher,
- wherein the molten 2,3,3′,4′-biphenyltetracarboxylic dianhydride is supplied to a solidifying apparatus comprising a cooling surface and cooled on the cooling surface to give solid 2,3,3′,4′-biphenyltetracarboxylic dianhydride.
Dependencies are inferred from the claim text.