Extrusion method and apparatus

A process for extruding thermally activatable material on a substrate comprising:

• (a) feeding the thermally activatable material into an extruder via a feed section, wherein the feed section compresses and moves the thermally activatable material to an extrusion screw;
• (b) moving the thermally activatable material along the extrusion screw within a barrel of the extruder through a plurality of zones by rotating the extrusion screw and engaging the thermally activatable material with grooves of the barrel, wherein the grooves are equally spaced around an internal diameter of the barrel along a length of the extrusion screw, and wherein a length to diameter ratio of the barrel is 20 to 16 and the plurality of zones includes:
• (i) a first zone in which the thermally activatable material is cooled by a cooling fluid, wherein a length to diameter ratio of the barrel in the first zone is in the range of 2 to 5, and wherein at least a portion of the grooves is located in the first zone;
• (ii) a second zone in which the thermally activatable material is heated to a temperature above a melting point of the thermally activatable material but below an activation temperature of the thermally activatable material;
• (iii) a third zone;
• and
• (iv) a fourth zone, wherein the third zone and the fourth zone each further gradually heat the thermally activatable material to a temperature above the melting point but below the activation temperature;
• (c) passing the thermally activatable material from the extrusion screw through an extrusion die as a molten material, wherein the extrusion die is a single component with its own heating system, and the extrusion die is mounted to the barrel at a downward angle relative to the barrel;
• and
• (d) extruding the thermally activatable material onto the substrate at a temperature below the activation temperature where the thermally activatable material bonds to the substrate and cools, wherein the extrusion screw operates at 10 to 50 revolutions per minute, and the extrusion screw rotates in a clockwise direction and a counterclockwise direction to create a discontinuous pattern or array of the thermally activatable material having one or more gaps free of the thermally activatable material so that the one or more gaps are spot welded;
• wherein a residence time of the thermally activatable material within the extruder is less than 5 minutes and a compression ratio, defined as a channel depth at an end of the extruder located near the extrusion die divided by a channel depth of the extruder in the first zone is in a range of 1.5 to 2;
• and
• wherein the substrate is pre-treated, prior to extrusion, by heating, infra-red treatment, plasma treatment, or a combination thereof.