The microtextured plastic moldings to control human tactile sense: The texture effect enhancement due to apical shape and material frictional properties

• The enhanced texture effect was obtained by the round texture with small pitch.
• The apical shape affects the magnitude of the texture effect.
• The enhanced effect of the material property was obtained by the round texture.

The purpose of this study is to develop a plastic molding with a distinguishing tactile character for various industrial applications. In the present paper, we investigated the effects of the apical shape of the texture and the frictional properties of the plastic material on the tactile sense of the textured plastic molding in order to enhance the texture effect. Based on the analyses conducted, it was found that both the apical shape and the material frictional properties affect the particular tactual sensation of the plastic molding. The “Uneven” and similar trend sensations, which are mainly dominated by the fluctuation of friction, were dependent on the apical shape due to the sticking characteristics of the fingerprint. The strength of these sensations was caused by the sharper apical shape. The “Sticky” sensation was dominated by the complex effect of the fluctuation of friction and the frictional properties of the plastic material. The larger texture effect elicited for “Slick” sensations was obtained at round and sharp textures with a pitch of 120 μm. The enhanced texture effect of material frictional properties was observed at the apical shapes with large contact area, and it was obtained at the round texture. However, flat texture elicited a similar sensation to that elicited by the nontextured surface as a result of the small texture effect and large contact area. These results indicate that control of the apical shape and material frictional properties is effective in enhancing the texture effect of the plastic molding surface.