1. Field of the Invention
The present invention relates to a mask as a hygienic material used on a face, covering the mouth and the nose, in particular, to a mask used in an operation room of a hospital or in a clean room of a semiconductor manufacturing plant.
2. Description of the Related Art
In a surgical operation room or in a clean room, contamination or fouling of the indoor air by the germ or dust is prevented by the use of a facial mask. Since the facial mask needs to have substantially the same shape as the facial contour around the mouth and the nose in order to effectively shield between the inner side and the outer side of the mask, various kinds of masks are on market, including the folded type comprising a fabric partially folded with the both edges fixed, and the three-dimensionally molded type having a preliminarily three-dimensional shape without deformation.
The folded type comprises a single rectangular fabric partially folded with the both edges fixed so that the mask main body portion forms a substantially three-dimensional convex shape by expanding the folded part. That is, although it is an ordinary facial mask with a two-dimensional shape, it can have a three-dimensional shape by expanding the folded part in use.
However, in addition to the inherent difficulty in breathing by having the mouth and the nose covered by a mask, since the material of the mask comprises a fine mesh as well as the rear side of the mask main body comes in direct contact with the mouth, the air-flow area tends to be narrow. As a consequence, the mask fabric slides whenever the user breathes normally or talks with the other staff members, resulting in causing further difficulty in breathing.
On the other hand, the three-dimensionally molded type can be used as it is, without deformation since the shape of the main body portion is formed three-dimensionally in the manufacturing process, and thus it is handy.
However, the need of the manufacturing equipment for molding integrally and the large-scale manufacturing process pushes up the manufacturing cost. Besides, storage or transportation of many facial masks results in generating dead space.