| 摘要 |
PURPOSE:To enable low noise level to be maintained by using a 2-tier rubber elastic body used for a roll, the outer layer having a required thickness at required modulus of elasticity and the inner layer having a required modulus of elasticity, a requiared dynamic magnifying rate and a required loss coefficient. CONSTITUTION:A roll is composed of a 2-tire rubber elastic substance adhered concentrically with a shaft used as the core, the outer layer consisting of a 2-7mm-thick elastic substance with a synthetic rubber base having 250kg/cm<2> or more of modulus of tensile elasticity at 5% elongation and the inner layer being made up of an elasttic substance having 30kg/cm<2>-120kg/cm<2> of modulus of tensile elasticity at 5% elongation, the ratio of 3 or less between the modulus of dynamic storage elasticity at 100Hz and 0.3% distortion and the modulus of tensile elasticity at 5% elongation, and 0.07-0.25 of loss coefficient at 100Hz, 0.3% distortion. If an outer layer elastic substance having 250kg/cm<2> or less of modulus of elasticity is used, satisfactory print cannot be obtained. Further, if an inner layer elastic substance having 0.25 or more of loss coefficient is used, an adequate low noise level cannot be reached. On the other hand, if said elastic substance having 0.07 or less is used, pring becomes unsatisfactory due to excess repulsive elasticity. |
