Method of preparing a polymeric coating composition from a blocked isocyanate-functional polymeric compound and a crosslinking agent which is insoluble in aprotic solvents

Claim 1

A method of preparing a storage-stable non-moisture reactive liquid coating composition which is homogeneous even when free of solvent and which may be thermally cured to form a polymeric film having urethane or urea linkages, comprising the steps of: (a) providing an isocyanate-functional polymeric compound which has more than about 70 percent of the isocyanate groups masked by agents that can be removed by heating; (b) adding a crosslinking agent, which is insoluble in aprotic solvents, to said masked isocyanate-functional polymeric compound, and allowing said crosslinking agent and said masked isocyanate-functional polymeric compound to react at an elevated temperature for a period of time which is sufficient to unmask no more than about one-third of said masked isocyanate-functional polymeric compound, in order to partially react said crosslinking agent and said unmasked isocyanate-functional polymer so as to form an oligomer in which the unreacted portions of said crosslinking agent and said masked isocyanate-functional polymer are soluble; and (c) maintaining said reaction at said elevated temperature until a homogeneous liquid solution results wherein said method can be performed in the absence of any solvent.

Claim 2

A method of preparing a storage-stable non-moisture reactive liquid coating composition which is homogeneous even when free of solvent and which may be thermally cured to form a polymeric film having urethane or urea linkages, comprising the steps of: (a) providing an isocyanate-functional polymeric compound which has more than about 70 percent of the isocyanate groups masked by agents that can be removed by heating; (b) adding a crosslinking agent, which is insoluble in aprotic solvents, to said masked isocyanate-functional polymeric compound, and allowing said crosslinking agent and said masked isocyanate-functional polymeric compound to react at an elevated temperature for a period of time which is sufficient to unmask no more than about one-third of said masked isocyanate-functional polymeric compound, in order to partially react said crosslinking agent and said unmasked isocyanate-functional polymer so as to form an oligomer in which the unreacted portions of said crosslinking agent and said masked isocyanate-functional polymer are soluble; and (c) maintaining said reaction at said elevated temperature until a homogeneous liquid solution results wherein said method can be performed in the absence of any solvent.

Claim 15

A method of preparing a thermally cured polymeric layer wherein the cured polymer contains urethane or urea linkages, comprising.the steps of: (a) providing an isocyanate-functional polymeric compound which has more than about 70 percent of the isocyanate groups masked by agents that can be removed by heating; (b) adding a crosslinking agent, which is substantially insoluble in aprotic solvents to said masked isocyanate-functional polymeric compound, and allowing said crosslinking agent and said masked isocyanate-functional polymeric compound to react at an elevated temperature for a period of time which is sufficient to unmask no more than about one-third of said mask isocyanate-functional polymer, in order to partially react said crosslinking agent and said unmasked isocyanate-functional polymer so as to form an oligomer in which the unreacted portions of said crosslinking agent and said masked isocyanate-functional polymer are soluble; (c) maintaining said reaction at said elevated temperature until a homogeneous liquid solution results; (d) coating said homogeneous liquid solution on a substrate so as to form a layer; and (e) heating said layer to a temperature which is at least equal to the minimum dissociation temperature for said masking agent, for a period of time sufficient to cure said thermally cured polymeric layer.

Claim 16

A method of preparing a thermally cured polymeric layer wherein the cured polymer contains urethane or urea linkages, comprising.the steps of: (a) providing an isocyanate-functional polymeric compound which has more than about 70 percent of the isocyanate groups masked by agents that can be removed by heating; (b) adding a crosslinking agent, which is substantially insoluble in aprotic solvents to said masked isocyanate-functional polymeric compound, and allowing said crosslinking agent and said masked isocyanate-functional polymeric compound to react at an elevated temperature for a period of time which is sufficient to unmask no more than about one-third of said mask isocyanate-functional polymer, in order to partially react said crosslinking agent and said unmasked isocyanate-functional polymer so as to form an oligomer in which the unreacted portions of said crosslinking agent and said masked isocyanate-functional polymer are soluble; (c) maintaining said reaction at said elevated temperature until a homogeneous liquid solution results; (d) coating said homogeneous liquid solution on a substrate so as to form a layer; and (e) heating said layer to a temperature which is at least equal to the minimum dissociation temperature for said masking agent, for a period of time sufficient to cure said thermally cured polymeric layer.