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1. A chemical mechanical (CMP) polishing pad for polishing a substrate chosen from at least one of a magnetic substrate, an optical substrate and a semiconductor substrate, the polishing pad comprising a polishing layer adapted for polishing the substrate, the polishing layer being a polyurethane, the polyurethane is a product of an organic solvent free two-component reaction mixture comprising (i) a liquid aromatic isocyanate component comprising one or more aromatic diisocyanates or a linear aromatic isocyanate-terminated urethane prepolymer having an unreacted isocyanate (NCO) concentration of from 18 to 40 wt. %, based on the total solids weight of the aromatic isocyanate component, and (ii) a liquid polyol component comprising a) one or more polymeric polyols, b) from 15 to 36 wt. %, based on the total weight of the liquid polyol component, of one or more small chain difunctional polyols having from 2 to 6 carbon atoms, c) from 0 to 25 wt. %, based on the total weight of the liquid polyol component, of a liquid aromatic diamine which is a liquid at standard pressure and at 40° C., and d) an amount of water or CO2-amine adduct sufficient to reduce the density of a CMP polishing pad made from the two-component reaction mixture to from 0.2 to 0.50 g/mL, wherein the reaction mixture comprises 60 to 75 wt. % of hard segment materials, based on the total weight of the reaction mixture, wherein the CMP polishing layer has a Shore DO (15 second) hardness of from 40 to 80, and with densities of from 0.2 to 0.50 g/mL.
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