Heat-resistant adhesives aromatic polyimides

JP 05306386 (Japanese) 1993 Heat-resistant adhesive composition Ube Industries, Japan H Inoe, S Takabayashi, T Muramatsu, T Hirano Resin formulation useful for bonding Cu foils to polyimide films for electronic applications Heat-resistant adhesives were formulated to include imide-siloxanes with softening points <300° C. Diaminopolysiloxanes and aromatic amines were used maleimide termination also utilized. 

JP 05311144 (Japanese) 1993 Heat-resistant adhesive compositions containing polyimide-siloxane block copolymers Ube Industries, Japan H Inoe, S Takabayashi, T Funakoshi, K Sonoyana Useful for Cu-clad laminates of printed circuit boards and tape-automated bonding with good flexibility and heat resistance Formulated compositions containing siloxane-imide block copolymers made from aromatic tetracarboxylic acids and aromatic diamines and aminosiloxanes... 

The general process used to synthesise aromatic polybenzimidazoles (PBIs) is presented in Section 4.3.3. More detailed information can be found in previously published books [87,88]. During 1960-1970 a number of publications, comparable to those on polyimides, reported the synthesis and properties of all aromatic and aryl-aliphatic polybenzimidazoles. Most of these polymers were prepared by the two-step process illustrated in Fig. 14 with the reaction of 1,3-benzenedicar-boxylic acid diphenyl ester 27 and [l,l -biphenyl]-3,3, 4,4 -tetramine 11 yielding ultimately PBI 29. All the applications - laminates and filament winding resins, adhesives, fibres and foams - used polymer 29, which was produced in semicommercial quantities by the Whittaker Corporation (Narmco Division) under the generic trade mark Imidite . Currently, forty years later, this polymer is manufactured by Hoechst-Celanese and its only commercial success is in the area of heat resistant fibres and fabrics. It is, however, worth noting the adhesive properties of this polymer and the reasons explaining the major obstacles to the development of PBIs as heat-resistant adhesives. 

Many trends in polymer synthesis generally are being applied, or could be applied in the future, to adhesives. There is a continuous stride toward polymers with superior heat resistance. To achieve this, various heterocyclic and aromatic structures are built into polymers, e.g., by intramolecular cyclization (polyimides, polybenzimidazoles), trimerization of terminal acetylene or nitrile groups, etc. Another route is to introduce highly stable perfluorinated units into the polymer. While heat-resistant polymers find their main applications as laminating... 

Fully imidized aromatic thermoplastic polyimides (TPI) are linear polymers with good thermomechanical performance, used in high-temperature (>230°C) applications. Pis based on aromatic diamines and dianhydrides exhibit excellent heat resistance. In addition to their outstanding high-temperature resistance (Sancaktar et al. 1984 Sancaktar and Schenck 1985 Sancaktar and Dembosky 1986), toughness and good dielectric properties, low flammability, and high radiation resistance are desirable characteristics for this class of adhesives. 

PAIs are unique materials that have elements of PA (aka nylon) chemistry, as well as aromatic polyimide chemistry. They have exceptional mechanical, chemical, and thermal properties and are considered by some to be at the top of the thermoplastic performance chart. They have high strength, exceptional high heat capability, and broad chemical resistance. Polyamide-imide polymers are melt processible and can be processed into a wide variety of forms—from injection- or compression-molded parts and ingots— to coatings, films, fibers, and adhesives. PAI is often lower in cost than TPI. 

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