Polishing pad and cushion layer for polishing pad

1. A method for producing a polishing pad having a polishing layer, comprising:

preparing an aqueous resin containing ionic groups in the range of 100-1100 eq/ton by introducing ionic groups into a polyester resin by copolymerizing a polyvalent carboxylic acid and a polyvalent alcohol, said ionic groups being selected from the group consisting of a carboxyl group, ammonium carboxylate group, sulfonate group, and alkali metal sulfonate;

preparing an aqueous dispersion of the aqueous resin by dissolving the aqueous resin in a water-soluble organic compound, adding water thereto, and removing the water-soluble organic compound;

mixing abrasive grains in the aqueous dispersion of the aqueous resin, wherein a homogenous dispersion without aggregation is formed;

applying the homogenous dispersion on a substrate to form a layer and drying the layer; and

forming a polishing pad using the layer as a polishing layer.

2. The method according to claim 1 , further comprising conducting graft polymerization of the copolymerized resin with a radical polymerizable monomer having ionic groups.

3. The method according to claim 1 , wherein the abrasive grains are made of at least one member selected from the group consisting of silicon oxide, cerium oxide, aluminum oxide, zirconium oxide, ferric oxide, chrome oxide and diamond.

4. The method according to claim 1 , wherein the content of abrasive grains in the polishing layer is 20 to 95% by weight.

5. The method according to claim 1 , wherein the substrate is a polyester sheet.

6. The method according to claim 1 , wherein the thickness of the polishing layer is 10 to 500 μm.

7. The method according to claim 1 , wherein the resin contains ionic groups in the range of 200-1100 eq/ton.