Process of making a diaphragm of carbonaceous material

Abstract

A process for producing a diaphragm for a speaker of fully carbonaceous materials which has the steps of mixing carbon powder in an organic binder carbonized after calcining, kneading the composition to uniformly mix and disperse, preliminarily molding it in a sheet shape, molding the preliminarily molded material in a diaphragm shape, insolubilizing, infusibilizing the mixture and calcining the mixture in an inert atmosphere, wherein the composition contains a titanate coupling agent. Thus, a rigid bonding strength is provided in the boundary between the organic binder and the carbon powder in the green state of the composition, and the mixture is calcined to industrially simply and inexpensively produce a diaphragm having a high hardness, a high elasticity, a high strength, a light weight, an adequately large internal loss (and thus less deformation by an external force) small distortion of sound, wide reproducing sound range, distinct sound quality and adapted for a digital audio. The process allows the mixing of a large quantity of carbon powder to perform excellent characteristics of the carbon powder by a composite rule.