Rotary process for forming uniform material
View Patent ↗A process is provided for issuing material from a nozzle in a rotor rotating at a given rotational speed wherein the material is issued by way of a fluid jet. The material can be collected on a collector concentric to the rotor. The collector can be a flexible belt moving in the axial direction of the rotor. The collected material can take the form of discrete particles, fibers, plexifilamentary web, discrete fibrils or a membrane.
1. A process comprising the steps of:
supplying a fluidized mixture having at least two components at a pressure greater than atmospheric pressure to a rotor spinning about an axis at a rotational speed, the rotor having at least one material-issuing nozzle comprising an opening therein along the periphery of the rotor;
issuing the fluidized mixture from the opening of the nozzle at a reduced pressure relative to that in the supplying step to form an issued material at a material issuance speed;
vaporizing or expanding at least one component of the issued material to form a fluid jet; and
transporting the remaining component(s) of the issued material away from the rotor by the fluid jet.
2. The process of claim 1 , wherein the fluidized mixture comprises at least about 50% by weight of a spin agent, and wherein the fluidized mixture is issued at a temperature greater than the boiling temperature of the spin agent.
3. The process of claim 2 , wherein the fluidized mixture comprises at least about 70% by weight of a spin agent.
4. The process of claim 1 , wherein the fluidized mixture comprises a compressed vapor.
5. The process of claim 1 , wherein the fluid jet is issued at a speed of at least about 30 meters per second.
6. The process of claim 1 , wherein one component comprises a spin agent, further comprising supplying the fluidized mixture to the rotor at a temperature greater than the boiling temperature of the spin agent at a pressure sufficient to keep the spin agent in liquid state, and issuing the fluidized mixture from the opening into an environment at a temperature within about 40° C. of the boiling temperature of the spin agent such that the spin agent vaporizes and a solidified second component is propelled from the nozzle.
7. The process of claim 6 , wherein the fluidized mixture is issued into an environment at a temperature within about 10° C. of the boiling temperature of the spin agent.
8. The process of claim 1 , further comprising collecting the remaining component(s) of the issued material on a collection surface of a collection belt concentric to the axis of the rotor to form a collected material, the collection belt moving in a direction parallel to the axis of rotation of the rotor at a collection belt speed.
9. The process of claim 8 , further comprising selecting the rotational speed and the collection belt speed so that the component(s) collected on the collection surface comprise multiple layers.
10. The process of claim 1 , wherein the at least one material-issuing nozzle spreads the issued material primarily in the axial direction.
11. The process of claim 1 , wherein the at least one material-issuing nozzle spreads the issued material primarily in a non-axial direction.
12. The process of claim 1 , wherein the at least one material-issuing nozzle directs the issued material primarily in the radial direction.
13. The process of claim 1 , wherein the at least one material-issuing nozzle directs the issued material primarily in a non-radial direction.
14. The process of claim 8 , wherein the at least one material-issuing nozzle directs the issued material in the direction of the movement of the collection belt.
15. The process of any of claims 1 – 14 , wherein the at least one material-issuing nozzle comprises a fan jet.
16. The process of claim 1 , wherein the rotor has two or more material-issuing nozzles comprising openings therein along the periphery of the rotor.
17. The process of claim 16 , wherein the material-issuing nozzles are spaced apart axially.
18. The process of claim 16 , wherein the material-issuing nozzles are spaced apart circumferentially.
19. The process of claim 1 , wherein the ratio of the tangential speed at the periphery of the rotor to the material issuance speed is less than or equal to 1.
20. The process of claim 8 , further comprising applying vacuum to the collection belt on the side opposite the collection surface.
21. The process of claim 8 or claim 20 , further comprising creating an electrical potential between the remaining component(s) of the issued material and the collection surface.
22. The process of claim 21 , further comprising applying a voltage to the collection belt and grounding the rotor.
23. The process of claim 21 , wherein the collection belt is supported by an electrically conductive support structure, further comprising applying a voltage to the support structure and grounding the rotor.
24. The process of claim 21 , further comprising applying a voltage to the rotor and grounding the collection belt.
25. The process of claim 21 , wherein the rotor further comprises charging elements and a voltage is applied to the charging elements.
26. The process of claim 25 , wherein the charging elements are pins directed radially towards the collection surface.
27. The process of claim 25 , wherein the charging elements are pins directed tangentially towards the opening of the nozzle(s).
28. The process of claim 8 , wherein the collection surface is located a distance of between about twice the thickness of the collected component(s) and about 15 cm from the nozzle.
29. The process of claim 28 , wherein the collection surface is located a distance of between about 0.5 cm and about 8 cm from the nozzle.
30. The process of claim 1 , wherein the fluidized mixture comprises polyolefin.
31. The process of claim 8 , further comprising heating the collected material to a temperature sufficient to bond the material.
32. The process of claim 8 , wherein the collected material comprises a polymeric fibrous material and further comprising passing hot gas through the collected material at a temperature sufficient to bond the material.
33. The process of claim 8 , wherein auxiliary gas is supplied to a cavity between the rotor and the collection surface.
34. The process of claim 8 , further comprising issuing a liquid mist from at least one fogging jet nozzle located along the periphery of the rotor.
35. The process of claim 1 , wherein the fluidized mixture is a solution.
36. The process of claim 35 , wherein the fluidized mixture is a solution comprising a polymer and a volatile spin agent and forms a plexifilamentary film-fibril material.
37. The process of claim 1 , wherein the fluidized mixture is a solution comprising a polymer and a volatile spin agent and forms polymeric beads.
38. The process of claim 1 , wherein the fluidized mixture is a mixture of pulp and fluid.
39. The process of claim 1 , wherein the fluidized mixture is a mixture of particles and fluid.
40. The process of claim 1 , further comprising flowing a gas through the rotor.
41. The process of claim 1 , wherein the fluidized mixture is supplied to multiple nozzles, and wherein a portion of the nozzles spread the issued material at a first angle between about 20 and 40 degrees from the axial direction and a portion of the nozzles spread the issued material at a second angle opposite the first angle with respect to the axial direction.