Method of forming a seal

In a method of making a collapsible tube having a separately made rigid plastic head portion with a dispensing orifice therein, and separately made tube body of a laminate of plastic and metal foil, wherein the heat and tube body are welded together with radio frequency waves,

• the improvement comprising
• the method of forming a seal of a laminate of plastic and metal across the dispensing orifice of the tube, comprising
• (1) applying the seal to the dispensing orifice of the head before the head is welded to the tube body by
• (a) moving a file of heads past a first station;
• (b) stopping each head intermittently at the first station;
• (c) continuously applying a vacuum to the head and dispensing orifice from below the head at the first station;
• (d) passing a web of laminate over the head adjacent the dispensing orifice at the first station;
• (e) cutting a seal from the web of laminate adjacent the dispensing orifice;
• (f) keeping the seal of laminate positioned on the head over the dispensing orifice by means of the vacuum;
• (g) applying a hot press to the seal to fuse the seal to the head;
• and
• (h) terminating the vacuum below the head to the dispensing orifice, and
• (2) inserting a heat sink adjacent the seal during the welding by radio frequency waves of the head to the tube body, whereby any buildup of heat in the laminate seal is dissipated away from the seal to prevent damage to the seal.