A modified polyurethane carrier substrate is provided. The modified polyurethane carrier substrate is formed from a modified polyurethane. The modified polyurethane includes a soft segment and a hard segment. The soft segment is formed from a polyol. The hard segment is formed from diisocyanate and a chain extender. The chain extender is dianhydride. A common logarithm of a ratio of a storage modulus of the modified polyurethane carrier substrate at 30 C. to a storage modulus of the modified polyurethane carrier substrate at 150 C. ranges from 0.40 to 1.30.

Disclosed in the present invention are an isocyanate composition, a modified composition, and a polyurethane elastomer, the isocyanate composition having an effective factor of 3.80-5.30. By means of designing and controlling the effective factor, the isocyanate composition has excellent reaction activity and thus can be used for preparing high-performance polyurethane products. The isocyanate composition can improve stability of polyurethane products, and particularly, can remarkably improve resistance to color changes and weather resistance of polyurethane elastomers, suppress increases of color codes and yellowing under humid and hot conditions, and improve the tensile strength and tearing strength of polyurethane elastomers, such that the polyurethane elastomers have excellent comprehensive performance in the areas such as weather resistance, stability and mechanical properties.

A film-forming thermoset coating composition includes: (a) an aqueous medium; and Option 1 and/or Option 2 as follows: Option 1: (b1) polyurethane-acrylate core-shell particles including a polymeric acrylic core at least partially encapsulated by a polymeric shell including urethane linkages, where the polymeric shell includes an acid functional group and two or more hydrazide functional groups, where the polymeric shell is covalently bonded to at least a portion of the polymeric core; and (c1) (i) formaldehyde; (ii) polyformaldehyde; and/or (iii) a compound that generates formaldehyde; Option 2: (b2) polyurethane-acrylate core-shell particles including a polymeric acrylic core at least partially encapsulated by a polymeric shell including urethane linkages, where the polymeric shell includes an acid functional group and two or more N-methylolated hydrazide functional groups, where the polymeric shell is covalently bonded to at least a portion of the polymeric core.