Peelable bonded structures and process for preparing same

A process for preparing peelable bonded structures comprising a first article composed of metal and a second article bonded to the first article through a composite coating layer, said process comprising:

• (a) applying to the first article a paint composition comprising (i) an olefin resin (A) modified with a copolymerized carbonyl group-containing ethylenically unsaturated monomer whereby said modified olefin resin contains carbonyl groups at a concentration of between about 0.01 and 200 milliequivalents per 100 g of the modified olefin resin and having a degree of crystallization of at least 50%, and (ii) a coating film-forming base resin (B) at an (A)/(B) weight ratio of between about 0.2/99.8 and 40/60 and having a density greater by about 0.1 than the density of the modified olefin resin in a mixed solvent containing at least about 70% by weight of a solvent component having a solubility parameter of between about 8.5 and 9.5, said mixed solvent being further characterized in that the difference between the boiling points of the highest and lowest boiling solvent components is at least about 20.degree. C.;
• (b) curing the applied paint composition to form a first coating layer having a multi-layer distribution structure with resin concentration gradients in the thickness direction such that the modified olefin resin is distributed predominantly in the portion contiguous to the interface between the first and second coating layers and the base resin is distributed predominantly in the opposite portion;
• (c) applying another paint composition onto the first coating layer to form a second coating layer;
• and
• (d) heat-bonding a second article having the second coating layer pre-formed thereon to the first coating layer having the multi-layer distribution structure formed therein so that the articles have a peel strength of between about 0.05 and 5/kg/cm between the first and second coating layers.