| 摘要 |
<P>PROBLEM TO BE SOLVED: To provide a polyurethane sheet, securing flatness of a held material to be polished in polishing by holding the material to be polished flat. <P>SOLUTION: A back pad 1 includes a polyurethane sheet 4. The polyurethane sheet 4 has a skin layer 4a provided with micro-pores formed on the holding surface P side and a nap layer 4b provided inside the skin layer 4a. Foam 3 larger than the space volume of the pores formed in the skin layer 4a is formed in the nap layer 4b. In manufacturing the polyurethane sheet 4, pores 2 are formed in the holding surface P by a cellulose derivative to which polyurethane resin solution is added. The pores 2 are communicated with the foam 3 of the nap layer 4b. The diameter of the communicating hole communicating the pore 2 with the foam 3 is set larger than that of the micro-pores of the skin layer 4a. Air caught between the skin layer 4a and the material to be polished is stored in the foam 3. <P>COPYRIGHT: (C)2006,JPO&NCIPI |
