PURPOSE: To improve deaeration properties by pressing a mother mill having specified groups each composed of projections onto an embossing roll while rotating it, transferring the projections and forming the groups each composed of projections on a sheet or a film through the embossing roll.
CONSTITUTION: A mother mill is patterned by machining so that units each composed of six projections at the vertexes of a regular hexagon with sides each having a length L and one projection at the central part thereof may be arranged in a distribution state where four projections of a unit α represented by 2 and composed of a group of projections by 2 and a unit β represented by 3 and composed of a group of projections, mutually facing to each other form a regular square with sides each having a length L. While being rotated, the mother mill is then pressed onto an embossing roll so as to transfer the pattern. Further, the mother mill is shifted in blocks of one or several rows of the units of projections so as to press and transfer the pattern over the whole width of the embossing roll. By using the resultant embossing roll, many fine projections are made at least on one side of a sheet or a film of a thermoplastic resin such as polyurethane, thus producing the objective interlayer for a laminated glass, excellent in deaeration properties.
SONAKA TAKANORI