Polishing pad, production method for same, and production method for glass substrate

1. A polishing pad having a polishing layer comprising a thermoset polyurethane foam,

wherein about the thermoset polyurethane foam, the Asker C hardness value thereof is 82 or less as a 60-second value, the hardness value being a value after the foam is immersed in water for 24 hours, and further the value of the tensile storage modulus E′ (30° C.) thereof at a frequency of 1.6 Hz satisfies the following expression (1):

Y< 5 X− 150  (1)

wherein Y represents the tensile storage modulus E′ (MPa), and X represents the Asker C hardness value (60-second value) after the foam is immersed in water for 24 hours.

2. The polishing pad according to claim 1 , wherein the thermoset polyurethane foam comprises, as raw material components, an isocyanate component, and active-hydrogen-containing compounds comprising 5 to 20% by weight of a polyol compound having a functional group number of 2 and a hydroxyl group value of 1,100 to 1,400 mg KOH/g, and 10 to 40% by weight of a polyol compound having a functional group number of 3 and a hydroxyl group value of 200 to 600 mg KOH/g.

3. The polishing pad according to claim 1 , wherein about the thermoset polyurethane foam, the Asker C hardness value thereof, as the 60-second value, is 75 or less, the hardness value being a value after the foam is immersed in water for 24 hours.

4. The polishing pad according to claim 1 , wherein the value of the tensile storage modulus E′ (30° C.) at the frequency of 1.6 Hz is 100 MPa or less.

5. The polishing pad according to claim 1 , wherein the thermoset polyurethane foam has substantially spherical continuous bubbles having an average bubble diameter of 20 to 300 μm.

6. A method for producing a glass substrate, comprising the step of:

providing the polishing pad of claim 1 ; and

polishing a glass substrate using the polishing pad.