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US 2020/0324317 A1Published application
Extrusion method and apparatus
AssigneeZephyros, Inc.
InventorsVincent Hoff, Christophe Epp
Life of this patent
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Abstract
Improvements in the extrusion of thermohardenable materials are achieved by cooling the material in the initial zone of the extruder and reducing residence time by use of a prescribed length to diameter ratio and screw speed, particularly useful for intermittent application during robotically controlled mass production.
Claims21
1:
- A process for extruding thermally activatable material on a substrate comprising:
- (a) feeding the thermally activatable material into an extruder via a feed hopper;
- (b) moving the thermally activatable material along an 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 extrusion screw, wherein the plurality of zones includes:
- (i) a first zone in which the thermally activatable material is cooled by a cooling fluid;
- and
- (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 the activation temperature of the thermally activatable material;
- (c) passing the thermally activatable material from the extrusion screw through an extrusion die as a molten material;
- and
- (d) extruding the thermally activatable material onto the substrate at a temperature below the activation temperature where it bonds to the substrate and cools.
6 more elements
2-34. (canceled)
35:
- The process of claim 1, wherein the plurality of zones includes a third zone and a fourth zone that each further gradually heat the thermally activatable material to the temperature above the melting point but below the activation temperature.
36:
- The process of claim 35, wherein the second zone, the third zone, and the fourth zone each have a separate heating system to heat the thermally activatable material in a controlled manner.
37:
- The process of claim 1, wherein the second zone is heated to a temperature in the range of 20° C. to 40° C.
38:
- The process of claim 35, wherein the third zone is heated to a temperature in the range of 40° C. to 80° C.
39:
- The process of claim 38, wherein the fourth zone is heated to a temperature in the range of 80° C. to 120° C.
40:
- The process of claim 1, wherein the first zone is cooled by a cooling jacket containing the cooling fluid and a temperature of the cooling fluid leaving the cooling jacket does not exceed 10° C.
41:
- The process of claim 40, wherein the thermally activatable material is conveyed as a solid through the first zone.
42:
- The process of claim 1, wherein the extrusion die is a single component with its own heating system that further heats the thermally activatable material prior to extruding the thermally activatable material onto the substrate.
43:
- The process of claim 1, wherein the grooves of the extrusion screw are only located along the extrusion screw in the first zone.
44:
- The process of claim 1, wherein the grooves extend along the extrusion screw along an entire length of extrusion screw through the plurality of zones.
45:
- The process of claim 43, wherein the grooves are equally spaced around an internal diameter of the barrel along a length of the extrusion screw.
46:
- The process of claim 1, wherein a residence time of the thermally activatable material within the extruder is less than 5 minutes.
47:
- The process of claim 1, wherein 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 the range of 1.5 to 2.
48:
- The process of claim 1, wherein a length to diameter ratio of the barrel is 20 to 16.
49:
- The process of claim 47, wherein the extruder screw operates at 10 to 50 revolutions per minute, and the extruder screw rotates in a clockwise and a counterclockwise direction.
50:
- The process of claim 48, wherein a length to diameter ratio of the barrel in the first zone is in the range of 2 to 5.
51:
- The process of claim 1, wherein a gap exists between an end of the extrusion screw and the substrate prior to the extrusion of the thermally activatable material onto the substrate, and the gap is filled immediately prior to commencement of the extrusion of the thermally activatable material onto the substrate.
52:
- The process of claim 51, wherein the thermally activatable material is sucked back into the gap when extrusion is to be terminated.
53:
- The process of claim 52, wherein the substrate is pre-treated prior to extrusion by heating, infra-red treatment, plasma treatment, or a combination thereof.