Method of butt-jointing metal tapes coated with a thermoplastic polymer film

A method of butt-jointing tapes of a conductive metal coated on one or both sides with a film of a thermoplastic polymer material selected from the group consisting of a hybrid film of ionomer polymer for bonding to the metal and high-density polyethylene, and a polyisocyanate or epoxy resin adhesive for bonding a film of low-density polyethylene to the metal, as part of a process for manufacturing a composite product involving the continuous feeding of a tape of the metal coated with the thermoplastic polymer film, said method comprising the following steps:

• (a) cutting the ends of the two tapes at predetermined matching oblique angles to the feed direction;
• (b) detaching the thermoplastic polymer film from the end portion of each tape by immersion for a time interval just sufficient to detach the film in a solvent maintained at its boiling point;
• (c) mechanically stripping the detached thermoplastic polymer film from the tape end portions;
• (d) welding the end portions of the two tapes together;
• (e) covering at least the stripped end portions of the two tapes with a polymer film bondable to the tapes by the application of heat, the portions of the tapes so covered being placed between two metal plates which have at least their surface in contact with the thermoplastic film coated with a heat-resistant material to which the film will not adhere;
• (f) placing the metal plates between heated press plates and compressing them to a high pressure;
• and
• (g) rapidly cooling the press plates and moving them apart to enable the metal plates to be removed.