| 摘要 |
<P>PROBLEM TO BE SOLVED: To provide a polishing sheet settled such a problem that the conventional polishing sheet has very large unevenness of hardness, foam size and the like, wherein the polishing sheet for precision polishing is produced by a batch-wise method for recent about 20 years or more and the method comprises secondarily processing a large sized resin block into required thin sheets. <P>SOLUTION: The homogeneous polyurethane-polyurea polishing sheet has at least 0.25 or more bulk density and ≤5% bulk density difference between the bulk density of each layer and that as a whole when the sheet is divided into two layers in thickness direction, and the sheet is produced by a continuous process comprising (a) a step for compounding and mixing predetermined ingredients into two or three components as polyurethane-polyurea polishing sheet materials, (b) a step for discharging the obtained between confront two crawler stainless steel belts having ≤25 mm effective space therebetween and (c) a step for heating to perform, when required, practical curing between the belts. <P>COPYRIGHT: (C)2004,JPO |
