Layer multiplying die for generating interfacial surfaces

Patent metadata

Field	Value
Publication number	US-9364988-B2
Application number	US-201213424023-A
Country	US
Kind code	B2
Filing date	Mar 19, 2012
Priority date	Mar 17, 2011
Publication date	Jun 14, 2016
Grant date	Jun 14, 2016

Abstract

A method for generating interfacial surfaces within a first composite stream having a generally planar layer interface lies generally in an x-z plane of an x-y-z coordinate system. The method includes dividing the first composite stream into a plurality of branch streams along the x-axis such that the pair of discrete overlapping layers and the generally planar layer interface are distributed among at least two branch streams. Within each individual branch stream of the at least two branch streams, the width dimension of the branch stream is expanded along the x-axis and the thickness dimension of the branch stream is simultaneously contracted along the y-axis. The branch streams are recombined in an overlapping relationship, after each of the at least two branch streams is simultaneously expanded and contracted, to form a second composite stream having a greater number of discrete overlapping layers of polymeric material than the first composite stream.

First claim

Having described the invention, the following is claimed:

1. A method for generating interfacial surfaces within a first composite stream comprised of discrete overlapping layers of polymeric material, a pair of such discrete overlapping layers defining a generally planar layer interface therebetween which lies generally in an x-z plane of an x-y-z coordinate system, wherein the z-axis extends in the general direction of flow of the first composite stream, the x-axis extends transversely of the first composite stream and defines a width dimension of the first composite stream and the pair of discrete overlapping layers, and the y-axis extends perpendicularly away from the planar layer interface and defines a thickness dimension of the first composite stream and the pair of discrete overlapping layers, the method comprising the steps of:
(i) dividing the first composite stream into a plurality of branch streams along the x-axis such that the pair of discrete overlapping layers and the generally planar layer interface defined therebetween are distributed among at least two of the branch streams;
(ii) within each individual branch stream of the at least two branch streams, expanding the width dimension of the branch stream along the x-axis and simultaneously contracting the thickness dimension of the branch stream along the y-axis; and
(iii) recombining the branch streams, after simultaneously expanding and contracting each of the at least two branch streams, in an overlapping relationship to form a second composite stream which comprises a greater number of discrete overlapping layers of polymeric material than the first composite stream, wherein collectively steps (i)-(iii) have a homogenized velocity profile.

2. The method of claim 1 , wherein expansion of the branch streams along the x-axis is uniform and contraction of the branch streams along the y-axis is uniform.

3. The method of claim 1 further comprising repositioning the branch streams along the x-axis as the branch streams flow along the z-axis prior to simultaneously expanding and contracting the branch streams.

4. The method of claim 1 further comprising repositioning the expanded and contracted branch streams along both the x-axis and y-axis prior to recombining the branch streams in an overlapping relationship.

5. The method of claim 4 , wherein the expanded and contracted branch streams are positioned in a stacked configuration along the y-axis prior to being recombined.

6. The method of claim 1 , wherein the branch streams are recombined by simultaneously directing the expanded and contracted branch streams towards one another along the x-axis and the y-axis.

7. The method of claim 1 , wherein the first composite stream includes a single planar layer interface and the second composite stream includes three planar layer interfaces.

8. The method of claim 1 , wherein the branch streams are expanded along the x-axis an amount that is inversely proportionate to the amount the branch streams are contracted along the y-axis.

9. The method of claim 1 further comprising maintaining the cross-sectional area of the branch streams during each of steps (i)-(iii) at a substantially constant amount.

10. The method of claim 1 , wherein the first composite stream is divided into substantially identical branch streams each of which has one of a rectangular or square cross-section.

11. The method of claim 1 , further comprising providing a die for multiplying the planar layer interface between discrete overlapping polymeric layers of the first composite stream, the die comprising:
a first sub-element having conduits for dividing the composite stream into branch streams;
a second sub-element having tapered conduits, each tapered conduit receiving the corresponding branch stream and simultaneously expanding the corresponding branch stream along the x-axis and contracting the corresponding branch stream along the y-axis;
a third sub-element having conduits for recombining the branch streams in an overlapping relationship, after the branch streams are simultaneously expanded and contracted, to form the second composite stream having a greater number of discrete overlapping layers of polymeric material than the first composite stream.

12. The method of claim 11 , wherein the die further comprising a fourth sub-element positioned between the second sub-element and the third sub-element, the fourth sub-element having conduits for repositioning the expanded/contracted branch streams along the y-axis.

13. The method of claim 11 , wherein each conduit of the second sub-element tapers uniformly outwardly along the x-axis and tapers uniformly inwardly along the y-axis.

14. The method of claim 10 , wherein the conduits of the third sub-element merge to a single conduit within the third sub-element for merging the branch streams into the second composite stream.

15. The method of claim 11 , wherein the single conduit of the third sub-element includes a flat land extending parallel to the z-axis for relieving stress on the second composite stream.

16. The method of claim 11 , wherein the first composite stream includes a single planar layer interface and the second composite stream includes three planar layer interfaces.

17. The method of claim 11 , wherein the cross-sectional area of each tapered conduit of the second sub-element is substantially constant along the entire length of the tapered conduit in the z-direction.

18. The method of claim 1 , wherein the branch streams are expanded along the x-axis an amount that is inversely disproportionate to the amount the branch streams are contracted along the y-axis.

19. The method of claim 1 , wherein the first composite stream includes at least one highly elastic material.

20. The method of claim 1 , wherein the first composite stream includes rubber.

21. The method of claim 1 , wherein the first composite stream includes two materials having different viscosities.

Assignees

• Maia Joao
• Silva Jorge
• Harris Patrick
• Univ Case Western Reserve

Inventors

• Maia Joao
• Silva Jorge
• Harris Patrick

Classifications

• B29C48/18 Primary

  the components being layers · CPC title

• B29C48/92

  Measuring, controlling or regulating · CPC title

• B29C48/71

  for layer multiplication (extrusion of multi-component articles B29C48/16) · CPC title

• B29C48/08

  flexible, e.g. films · CPC title

• B29C2948/92514

  Pressure · CPC title