Thermosetting covering sheet and a method of forming hard coating on the surface of substrates using the same

A thermosetting covering sheet comprising a semihardened layer made of a thermosetting resin composition,

• wherein said thermosetting resin composition comprises, as main ingredients, a reactive acrylic resin, which is in a solid state at room temperatures, and a blocked isocyanate, said reactive acrylic resin containing a plurality of at least one kind of functional group selected from the group consisting of hydroxyl, amino, and carboxyl, and the weight average molecular weight of said reactive acrylic resin being in the range of 100,000 to 1,000,000, and
• the ratio of the number of isocyanate groups in said blocked isocyanate to the number of functional groups in the reactive acrylic resin (number of isocyanates/number of functional groups) is within the range of 0.5 to 2.0, the number of functional groups being the sum of the number of hydroxyl, amino, and carboxyl groups, and
• said resin composition is in the form of a preformed thermosetting covering sheet comprising a semihardened resin layer made of said resin composition, the proportion of functional groups of the reactive acrylic resins in said semihardened layer that have already reacted being from 1% to 80% based on the total number of functional groups of reactive acrylic resins present before reaction, and
• said thermosetting covering sheet being capable of being laid onto a surface of an object and being subsequently hardened to result in a permanent coating.