摘要：

1451714 Surfaces coated with carboxylic acid dihydrazide olive aldehyde polymers LOCKHEED AIRCRAFT CORP 11 March 1974 10791/74 Heading B2E [Also in Division C3] High emissivity is displayed by surfaces coated with a polymer obtained by condensing a dihydrazide of a cyclic tri- or tetra-carboxylic acid having all the carboxyl groups attached to ring carbon atoms, said hydrazide having at least one carboxyl group and hyd- razide group on adjacent carbon atoms, with a diol and an aldehyde at 95-120C to form a polyamic acid which is then heated above 120C to give a polymer containing cyclic hydrazide groups. For example, from pyromellitic dihydrazide, CH 2 O and a diol HOROH are obtained a polyamic acid of unit and a final product of unit In Example 21 titanium is coated with a solution in N-methyl pyrrolidinone of the cyclized polymer from pyromellitic dihydrazide, 1:5-pentanediol and formaldehyde. A rigid foam is prepared by dipping a polyamideimide foam onto an N-methyl pyrrolidinone solution of the cyclised polymer in example 19.

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