Recently, optical components such as optical lenses and optical recording media have been required to satisfy high density, high heat resistance and stable production; and for satisfying these requirements, for example, a method of producing optical three-dimensional molded articles (optical components) by pressing a shaping mold against a resin material to thereby form a specific micropattern or an odd-shaped article has been investigated (for example, see Patent Document 1).
The method of producing optical three-dimensional molded articles includes two types from the viewpoint of dimensional stability. For example, there are mentioned (1) a method including hot-melting a thermoplastic material, then pressing a shaping mold against it, and cooling it to obtain a molded article having a specific shape; and (2) a method including pressing a shaping mold against a photocurable resin, and then irradiating it with light through the shaping mold or a substrate to obtain an optical, three-dimensional molded article having a specific shape.
In general, these two types of methods are selected depending on the required heatproof temperature; and for example, in the field not requiring heat resistance, the method (1) of using a transparent thermoplastic resin such as polymethyl methacrylate (PMMA) or polycarbonate is widely employed. On the other hand, in the field of requiring heat resistance for reflow soldering or autoclaving etc., application of a photocurable resin including an epoxy resin as the main ingredient has been investigated, and the method (2) is being put into practical use.
In producing optical three-dimensional molded articles according to the method (2), a material curable within a short period of time is used, and the optical three-dimensional molded articles thus produced are required to have high transparency and excellent mechanical properties.
In the photocurable resin composition for the method (2), an antimony compound-based photopolymerization initiator excellent in curability, transparency, mechanical strength and thermal decomposition resistance has been heretofore much used. However, antimony compounds are highly toxic and are considered as worrisome, environmental load substances; and these days, therefore, more ecological materials including an antimony-free photopolymerization initiator are specifically noted (for example, see Patent Document 2).
Patent Document 1: Japanese Patent No. 3926380
Patent Document 2: WO2005/116038