| 摘要 |
<p>A non-birefringent optical resin material of a combination of a resin material and an inorganic particle material in a relation in which the signs of their birefringences are the same. The inorganic particles are dispersed in a molten resin material and made to coexist therewith. The organic particles and the molten resin material have birefringences of the same signs. The dispersed system is made to flow into a mold (4) through a gate (5). The molten material flows radially and spreads. The velocity vector of the flow has normal components P, R in addition to the straight-ahead component S. The bond chains of the resin material are oriented generally along the velocity vector. The bond chains of the resin material at and near points A, B on the equiphase surface (7) are oriented generally in the direction from the exit of the gate (5) toward points A, B. The flow velocity has a gradient around a particle. As a result, a moment acts, and the major axes of inorganic particles tend to be oriented generally parallel to the equiphase surfaces (6 to 9) of the flow. Therefore, the orientation birefringences of the materials cancel each other as a whole.</p> |
