| 摘要 |
PROBLEM TO BE SOLVED: To obtain durability against easiness of deformation and repeating operation by forming a material of a holder for a writing instrument or the like of a mixture of thermoplastic polyethylene resin and thermoplastic polypropylene to an injection molding having specific hardness and specific bending elastic modulus. SOLUTION: A flexible wall 12 becomes substantially stepwise in a longitudinal section, is formed so that its rearward is gradually reduced in diameter, and thinly integrally formed. Since a rear barrel 7 integrally having such a wall 12 is a molding of the state thermoplastic polypropylene resin is uniformly dispersively mixed in thermoplastic polyethylene resin with a hardness of 90 to 100 degrees and bending elastic modulus of 2000 to 7000kg/cm<2> , an elongation is obtained even by relatively hard resin molding. The polypropylene resin in the polyethylene resin forms an island-like assembling part. In the case of deformation by a pressing operation, recovery of the island-like part is fast, and it is scarcely affected by influence of the repeating operation, and hence excellent durability is obtained. |
