Assembly of timepiece parts assembled using repositionable hot melt adhesive and process for assembling and repositioning such parts

A process for assembling and repositioning at least two timepiece parts with a repositionable hot melt adhesive, wherein said timepiece parts are held together in assembled position when said adhesive is at a temperature TA and can be repositioned in relation to one another when said adhesive is heated to a temperature TC, comprising the steps of:

• a) preparing a solution of an adhesive comprising at least one formulation having the form of a mixture of block copolymer chains comprising at least a first polymer block having a glass transition temperature Tg or a melting temperature Tf ranging between 40° C. and 200° C., and at least a second polymer block comprising at least pendant diene units X and having a glass transition temperature Tg or a melting temperature Tf lower than a temperature TDA, and of coupling molecules comprising at least two dienophile end groups Y, wherein said X units and said Y groups are arranged to be able to react with one another and to bond together with the Diels-Alder reaction at a temperature TDA and to be able to regenerate with the retro-Diels-Alder reaction at a temperature TRDA,
• where TA<TRDA≤TC, wherein temperature TDA ranges between 0° C. and 100° C., and temperature TRDA ranges between 50° C. and 200° C., and TDA is strictly lower than TRDA, and temperature TC is higher than the glass transition temperature Tg or the melting temperature Tf of the first polymer block,
• b) applying the solution of said adhesive to the timepiece parts
• c) drying
• d) placing the timepiece parts at a temperature higher than or equal to the glass transition temperature Tg or the melting temperature Tf of the first polymer block to reposition the timepiece parts
• e) cooling to a temperature lower than or equal to the glass transition temperature Tg or the melting temperature Tf of the first polymer block,
• f) placing the timepiece parts at a temperature higher than or equal to temperature TDA and lower than TRDA to link the block copolymer chains to one another with the coupling molecules by the Diels-Alder reaction so that the adhesive is in the form of a three-dimensional network
• g) heating said timepiece parts to the temperature TC to regenerate the mixture of block copolymer chains and of coupling molecules with the retro-Diels-Alder reaction
• h) repositioning the timepiece parts
• i) duplicating steps e) to f)
• j) if necessary, repeating steps g) to i) as many times as required to reposition the timepiece parts again.