경질 폴리 우레탄의 기계적물성에 미치는 첨가제의 영향

Abstract

Stern tube bearing is a shaft device playing important roles to reduce the friction of axial rotation and to support the weight of shaft. However, because there is no domestic producer of stern tube bering, imported stern tube bearings have many practical problems including prices, delivery and after services. This is why stern tube bearing should be localization. For the purpose of development of polyurethane resin for stern tube bearings, the effect of additives on the hardness, tensile strength and elongation of the polyurethane resin were systematically investigated. For the preliminary researches, depending on the type of curing agent, MOCA type and non-MOCA type polyurethanes were synthesized. Preliminary researches concluded that MOCA type polyurethane resin has more excellent mechanical properties than non-MPCA type for stern tube bearings. Therefore, MOCA type polyurethane was adapted as base resin of this research. The base polyurethane resins were synthesized at the following conditions. Molar ratio of Polyol to MOCA was 100 : 23.5, 1 hour's first curing was preformed at 110 ℃, and 15 hours' second curing was followed at 110 ℃ after demolding. Silica, calcium carbonate and graphite were selected as additives for the enhancement of mechanical properties of polyurethane resin. Effect of the type and the dosage of these additives on the hardness, tensile strength, elongation of the polyurethane resin were experimentally examined. Tensile strength of the polyurethane resins increased with the content for all three additives. However, addition of calcium carbonate and graphite showed only minor effect on the hardness of the resin. Polyurethane resin with silica showed relatively excellent hardness, tensile strength and improved elongation.