Yoshikazu Sasaki

Preparation of polyimide powder

PURPOSE: To prepare, with good reproducibility, polyimide powder suitable for heat compression molding, by heating an amide solvent solution of a biphenyltetracarboxylic acid component and an aromatic diamine component to a specified temp. under stirring. CONSTITUTION: Nearly equimolar amounts of a biphenyltetracarboxylic acid component and an aromatic diamine component are dissolved, at a temp. below 155°C, in an amide solvent in which the formed polyimide is soluble in less than 1wt%. The temp. of the resultant homogeneous solution with a low rotational viscosity is raised quickly to 160W300°C under stirring and is kept within the temp. range to form an aromatic polyimide with a logarithmic viscosity number of 0.2W1 (0.5g/100cc p-chlorophenol at 50°C) which is then precipitated as fine particles. The reaction soln. in which the aromatic polyimide has been precipitated may be aged at 160W300°C for 0.2W20hr to increase th logarithmic viscosity of the precipitated polyimide. COPYRIGHT: (C)1982,JPO&Japio

Comparison of one‐pot and two‐step polymerization of polyimide from BPDA/ODA

The one-pot method polymerization of polyimide was carried out from 3,3′,4,4′-biphenyl tetracarboxylic dianhydride (BPDA) and 4,4′-oxydianiline (ODA) by the use of p-chloro-phenol as the solvent. The behavior of the polymerization was compared with that of the two-step method. The imidization reaction in the one-pot method proceeds completely in this system at even a low temperature such as 100°C. In the course of the film preparation from the solution, the embrittlement occurs when the film is prepared from polyamic acid solution, while it does not occur in the case of that from the solution of the one-pot method. A molecular weight of polyimide film is almost the same as that of precursor polyimide in the solution. In the same way, that of polyimide film is almost the same as that of precursor polyamic acid. The mechanical properties of the polyimide film prepared by the one-pot method are similar to those by the two-step method.

Properties of copolyimides prepared from different tetracarboxylic dianhydrides and diamines

Various copolymides were prepared from two acid dianhydrides (BPDA, 3,3′,4,4′-biphenyl tetracarboxylic dianhydride; PMDA, pyromelitic dianhydride) and two diamines (PPD, p-phenylene diamine; ODA, 4,4′-oxydianiline). The thermal and mechanical properties of these polyimides were examined in detail. By appropriately selecting the ratios of the acid dianhydride component and the diamine component, polyimide films having desirable mechanical and thermal characteristics can be obtained. Further, it was proved that there is a correlation between the properties and the compositions of the copolyimides and that the properties could be estimated from the compositions by the use of multiple regression analysis.

Equilibrium of one-pot polymerization of polyimide

One-pot polymerization of polyimide from 3,3′,4,4′-biphenyl tetracarboxylic dianhydride (BPDA) and 4,4′-oxydianiline (ODA) was examined. The equilibrium in the polyimide with water was examined in detail in p-chlorophenol solution during the polymerization. The equilibrium constant was expressed by log K = 1.50 + 1433 (1/T). The polymerization reaction is exothermic. The molecular weight increased with decrease of temperature.