Variable thickness extrusion die

• US 4,197,069 A
• Filed: 09/25/1978
• Issued: 04/08/1980
• Est. Priority Date: 05/21/1976
• Status: Expired due to Term

• Current Assignee: Peter Cloeren Sr
• Original Assignee: Peter Cloeren
• Inventors: Cloeren, Peter
• Primary Examiner(s): Woo, Jay H.
• Application Number:
  US05/945,787
• Time in Patent Office: 561 Days
• Field of Search: 264/171, 425/131.1, 425/466, 425/462, 425/133.5
• US Class Current: 425/131.1
• CPC Class Codes: B29C 48/07 Flat, e.g. panels
• CPC Class Codes: B29C 48/08 flexible, e.g. films
• CPC Class Codes: B29C 48/21 the layers being joined at their surfaces
• CPC Class Codes: B29C 48/307 specially adapted for bringing together components, e.g. melts within the die

Abstract

An extrusion method for the formation of multi-layer laminates of thermoplastic materials comprising introducing melts of thermoplastic materials into separate feed channels and then into back pressure cavities of greater cross-section than the feed channels where transverse flow occurs under conditions of heat and pressure so as to stress-relief the molten thermoplastic materials, release strain therein and provide equal pressure distribution, passing the resulting thermoplastic materials into elongated flow restriction channels of smaller cross section then the back pressure cavities with the material exerting equal pressures along the length of the elongated flow restriction channel and converging the materials into a melt laminate at the exit end of the flow restriction channels. Also provided is an apparatus for conducting the method.

Claims

1. An extrusion apparatus for melt-laminating thermoplastic materials into multiple layers of desired thicknesses, said apparatus comprising:

(1) a die body forming an open-ended nozzle;

(2) a totally enclosed housing within said body;

(3) feed ports for introduction of thermoplastic materials into multiple flow channels, said flow channels traversing said housing and converging in a V-shaped opening leading to a die-exit channel at the exit end of said housing;

(4) adjustable divider means provided between any two of said flow channels, each of said divider means having a head portion and a point portion, said point portion extending into said V-shaped opening;

(5) adjustment means on said divider means, said adjustment means adapted to cause said head portion to move longitudinally or rotate around its axis to control and define the lateral area through which the point of said divider moves;

(6) the walls of said divider means, alone or together with said housing, forming in each of said flow channels, an arcuate, elongated back pressure cavity between said feed ports and said V-shaped opening, said cavity being of greater cross-section than the remainder of the corresponding flow channel; and

(7) the walls of said divider means, alone or together with the walls of said V-shaped opening, forming in each of said flow channels, a tapered flow-restriction channel between said back pressure cavity and said die-exit channel;

said flow-restriction channel terminating at the point of convergence of thermoplastic streams flowing through said flow channels, and said flow-restriction channel being of smaller cross-section than the corresponding back pressure cavity; and

the width of said flow-restriction channel being adjusted by said adjustment means;

whereby manipulation of said adjustment means adjusts flow-restriction channel width so as to induce sheer stress and cause the materials to converge at substantially equal velocities and viscosities in said V-shaped opening.

2. An apparatus according to claim 1 wherein said adjustable divider means is adjustable by rotating the head portion of said divider means about its axis.

3. An apparatus according to claim 1 wherein said longitudinal movement is provided by eccentric means around which the head of said divider means is rotated which causes at least one of said point portions to extend further into said V-shaped opening than another of said point portions.

4. An apparatus according to claim 1 wherein said adjustable divider is adjustable by sliding said divider means longitudinally.

5. An apparatus according to claim 1 wherein the die nozzle opening ranges from 0.001 inch to 1.00 inch.

6. An extrusion apparatus according to claim 1 wherein the adjustment at the V-shaped opening ranges from 1 to 100% of the opening.

7. An apparatus according to claim 1 wherein the extrusion apparatus has two flow channels and a single adustable divider blade.

8. An apparatus according to claim 1 wherein the extrusion apparatus has three flow channels and at least two adjustable divider blades.

9. An apparatus according to claim 1 wherein the extrusion apparatus has more than three flow channels.

10. An apparatus according to claim 1 wherein said adjustable means at said head portion is adjustable at a point exteriorly of the die body.