Apparatus and method for elevated temperature electrospinning

• US 20080122131A1
• Filed: 01/10/2008
• Published: 05/29/2008
• Est. Priority Date: 06/29/2004
• Status: Active Grant

• Current Assignee: Cornell Research Foundation Incorporated (Cornell University)
• Original Assignee: Cornell Research Foundation Incorporated (Cornell University)
• Inventors: Zhou, Huajun, Joo, Yong Lak
• Granted Patent: US 7,901,610 B2
• Time in Patent Office: Days
• US Class Current: 264/6
• CPC Class Codes: D01D 5/0007 Electro-spinning non-woven fabrics produced by electro-spinning D04H1/728
• CPC Class Codes: D01D 5/0023 the material being a polymer melt
• CPC Class Codes: D01D 5/0038 the fibre formed by solvent evaporation, i.e. dry electro-spinning
• CPC Class Codes: D01D 5/084 Heating filaments, threads or the like, leaving the spinnerettes
• CPC Class Codes: D01F 1/10 Other agents for modifying properties
• CPC Class Codes: D01F 6/625 derived from hydroxy-carboxylic acids, e.g. lactones
• CPC Class Codes: D04H 3/02 characterised by the method of forming fleeces or layers, e.g. reorientation of yarns or filaments
• CPC Class Codes: Y10S 425/217 Spinnerette forming conjugate, composite or hollow filaments

Abstract

Elevated temperature electrospinning apparatus comprises a pump upstream of or containing a resistance heater, means to shield applied electrostatic field from the resistance heater, and a temperature modulator for modulating temperature in the spinning region.

Claims

1-6. -6. (canceled)

7. A method for melt electrospinning production of non-woven fabric from meltable thermoplastic polymer or meltable thermoplastic polymer nanoclay nanocomposite, said method comprising the steps of

(a) melting thermoplastic polymer or nanocomposite in a melting zone,

(b) moving the thermoplastic polymer or nanocomposite through the melting zone by a force supplier upstream of or in the melting zone,

(c) forming droplets from the melted polymer or nanocomposite,

(d) providing an electric charge on the droplets to overcome the surface tension of a droplet to produce a jet of melted polymer or nanocomposite and provide unstable flow involving a plurality of electrically induced bending instabilities/whipping motions and elongation of and production of polymer or nanocomposite fibers,

(e) collecting of the elongated fibers to form a non-woven fabric.

8. The method of claim 7 additionally comprising at least one of the following steps (f) and (g):

(f) providing a temperature for the polymer or nanocomposite being subjected to electrically induced bending instabilities/whipping motions and fiber elongation so as to provide against premature solidification and to provide against induction of relaxation of molecular orientation without affecting the electrically induced bending instabilities,

(g) shielding to prevent induction of voltage in the melting zone.

9. The method of claim 8 comprising the additional step of annealing the collected fibers to impart stability and molecular orientation.

10. A method for high temperature solution electrospinning of non-woven fabric from thermoplastic polymer or thermoplastic polymer nanoclay nanocomposite that is not dissolvable at room temperature in an acceptable solvent, said method comprising the steps of:

(a) homogenizing the polymer or nanocomposite in solvent in an elevated temperature zone to form a solution of the polymer or nanocomposite in the solvent;

(b) maintaining the solution at a temperature sufficient for maintaining dissolution in a second elevated temperature zone;

(c) moving the solution through the second elevated temperature zone by a force supplier upstream of or at the second elevated temperature zone;

(d) forming droplets of the solution moved through the second elevated temperature zone;

(e) providing an electric charge on the droplets to overcome the surface tension of a droplet to produce a jet of polymer or nanocomposite solution and provide unstable flow involving a plurality of electrically induced bending instabilities/whipping motions and flashing off of solvent and elongation of and production of polymer or nanocomposite fibers;

(f) collecting the fibers to form a non-woven fabric.

11. The method of claim 10 additionally comprising at least one of the following steps (g) and (h):

(g) providing a temperature for the polymer or nanocomposite and solution thereof being subjected to electrically induced bending instabilities/whipping motions and fiber elongation to provide against premature solidification and to provide against induction of relaxation of molecular orientation and potentiate flashing off of solvent, without affecting the electrically induced bending instabilities,

(h) shielding to prevent induction of voltage in the second elevated temperature zone.

12. The method of claim 11, comprising the additional step of annealing the collected fibers to impart stability and molecular orientation.