Abstract: A urethane composition for making a sheet transport roll, the composition comprising: (A) a polyether polyol blend containing polytetramethyleneether glycol (PTMG) and polypropylene glycol (PPG) in a weight ratio of PTMG/PPG=99/1 to 50/50; (B) a polyisocyanate; and (C) a chain lengthening agent; the urethane composition in a cured state having a hardness of not smaller than 40, and a crosslinking density of 0.15 to 0.8 mmol/cm3 or an allophanate bond concentration of 0.03 to 0.07 mmol/g.

Abstract: A retard roller of non-ground surface type which is virtually free from adhesion of paper dust thereby to have an excellent friction coefficient sustain ability, and which is free from creaky noises at a relatively low sheet feeding speed; a retard roller of non-ground surface type having little variation in outer diameter; and a sheet feeder employing such a retard roller. The retard roller comprises a roller body and a shaft extending axially therethrough, the roller body having a textured roller surface comprising a multiplicity of island portions (10) and a sea portion (11) recessed from the island portions, the island portions and the sea portion each having a multiplicity of fine projections (12). The ratio S1/S2 of the total area S1 of the island portions to the area S2 of the sea portion preferably is 0.25 to 0.55. The fine projections preferably each have a height of 3 to 25 &mgr;m.

Abstract: A retard roller of non-ground surface type which is virtually free from adhesion of paper dust thereby to have an excellent friction coefficient sustainability, and which is free from creaky noises at a relatively low sheet feeding speed; a retard roller of non-ground surface type having little variation in outer diameter; and a sheet feeder employing such a retard roller. The retard roller comprises a roller body and a shaft extending axially therethrough, the roller body having a textured roller surface comprising a multiplicity of island portions (10) and a sea portion (11) recessed from the island portions, the island portions and the sea portion each having a multiplicity of fine projections (12). The ratio S1/S2 of the total area S1 of the island portions to the area S2 of the sea portion preferably is 0.25 to 0.55. The fine projections preferably each have a height of 3 to 25 &mgr;m.

Abstract: A less expensive sheet feed roller of a non-ground surface type for use as a pickup roller or a sheet feeding roller in a sheet feeder. The sheet feed roller is virtually free from adhesion of paper dust during use thereby providing an excellent friction coefficient sustainability. The sheet feed roller comprises a roller body and a shaft extending axially through the roller body, the roller body having a textured roller surface comprising a multiplicity of island portions (10) and a sea portion (11) recessed from the island portions the island portions and the sea portion each having a multiplicity of fine projections (12). The ratio S1/S2 of the total area S1 of the island portions to the area S2 of the sea portion preferably is 0.25 to 0.70. The fine projections preferably each have a height of 3 to 25 &mgr;m.

Abstract: A urethane composition for making a sheet transport roll, the composition comprising: (A) a polyether polyol blend containing polytetramethyleneether glycol (PTMG) and polypropylene glycol (PPG) in a weight ratio of PTMG/PPG=99/1 to 50/50; (B) a polyisocyanate; and (C) a chain lengthening agent; the urethane composition in a cured state having a hardness of not smaller than 40°, and a crosslinking density of 0.15 to 0.8 mmol/cm3 or an allophanate bond concentration of 0.03 to 0.07 mmol/g.