MELT-BLOWING DIE USING CAPILLARY TUBES

• US 3,825,379 A
• Filed: 04/10/1972
• Issued: 07/23/1974
• Est. Priority Date: 04/10/1972
• Status: Expired due to Term

• Current Assignee: Dwight T. Lohkamp, James P. Keller
• Original Assignee: Dwight T. Lohkamp, James P. Keller
• Inventors: Lohkamp, Dwight T., Keller, James P.
• Primary Examiner(s): Baldwin, Robert D.
• Application Number:
  US05/242,504
• Time in Patent Office: 834 Days
• Field of Search: 425/464,72 264/176F,178F
• US Class Current: 425/72.2
• CPC Class Codes: B29C 48/05 Filamentary, e.g. strands
• CPC Class Codes: B29C 48/10 flexible, e.g. blown foils
• CPC Class Codes: B29C 48/2566 Die parts
• CPC Class Codes: B29C 48/25686 for dies
• CPC Class Codes: B29C 48/3001 characterised by the material or their manufacturing process
• CPC Class Codes: B29C 48/305 having a wide opening, e.g. for forming sheets
• CPC Class Codes: B29C 48/345 Extrusion nozzles comprising two or more adjacently arranged ports, for simultaneously extruding multiple strands, e.g. for pelletising
• CPC Class Codes: D01D 4/025 Melt-blowing or solution-blowing dies
• CPC Class Codes: Y10S 264/75 Processes of uniting two or more fibers

Abstract

A melt-blowing die which has capillary tubes rather than drilled orifices is more easily fabricated and operates more effectually. Preferably, one end of each capillary tube is machined so as to terminate in an apex having an included angle within the range of 30* to 90*. Or the tubes can have conical ends with the same angle. The inside diameter of these tubes range from 0.010 to 0.025 inch and they connect with a chamber in the die. Preferably the die is a two-piece assembly and is fabricated by bolting the two pieces and including the capillary tubes in a solder layer.

Claims

1. A melt-blowing die having a generally triangular crosssection which comprises in combination:

a die block having a chamber for thermoplastic material, and a plurality of discrete smooth bore, uniform diameter, capillary tube means, having an internal diameter of from 0.010 to 0.025 inches and an external diameter of 0.025 to 0.050 inches each having one end and another end, rigidly held within said die block, and each of said tube means in a touching essentially planar relationship with each of said another ends in a precise alignment defining a sharp edge, said one end of said tube means in fluid connection with said chamber and said another end of said tube means having a shaped tip with a cross sectional angle within the range of 30* to 90* in fluid communication with the exterior of said die, and upper and lower gas slots defined by gas plates with tip means adjacent to said shaped tip in a spaced, parallel planar relationship to said shaped tip whereby said air plates form the same angle as said shaped tip.

2. A die according to claim 1 wherein said tip is triangular in cross section.

3. A die according to claim 1 wherein said tip is conical.

4. A die according to claim 1 wherein the centers of said tube means are aligned in substantially a single plane.

5. A die according to claim 1 wherein said angle is within the range of 55* to 65*.

6. A die according to claim 1 wherein said die block comprises an upper die block and a lower die block.

7. The die of claim 1 wherein said tube means are of circular cross section.

8. The die of claim 4 wherein the center of each tube means is offset from a straight line no more than 3 mils.

9. The die of claim 1 wherein said tube means are stainless steel capillary tubes aligned in a bed of solder.

10. The die of claim 9 wherein said die block has two discrete components and said tubes are rigidly mounted between said components.

11. The die of claim 1 wherein said gas plate tips are positioned essentially opposite said shaped tips.

12. The die of claim 1 which is at least 40 inches long and has at least 500 tube means.

13. In a melt-blowing apparatus comprising:

extruder means in combination with die means, said die means having gas attenuating means and fiber collecting means the improvement which comprises said die means having a generally triangular cross-section which comprises in combination;

a die block having a chamber for thermoplastic material, and a plurality of discrete smooth bore, uniform diameter, capillary tube means, having an internal diameter of from 0.010 to 0.025 inches and an external diameter of 0.025 to 0.050 inches each having a one end and another end, rigidly held within said die block, and each of said tube means in a touching essentially planar relationship with each of said another ends in a precise alignment defining a sharp edge. said one end of said tube means in fluid connection with said chamber and said another end of said tube means having a shaped tip with a cross sectional angle within the range of 30* to 90* in fluid communication with the exterior of said die, and upper and lower gas slots defined by gas plates with tip means adjacent to said shaped tip in a spaced, parallel planar relationship to said shaped tip whereby said air plates form the same angle as said shaped tip.

14. The melt-blowing apparatus of claim 13 wherein the die has an angle within the range of 55* to 65*.

15. The melt-blowing apparatus of claim 13 wherein the tube means IN said die are of circular cross-section.

16. The apparatus according to claim 13 wherein the die contains stainless steel capillary tubes aligned in a bed of solder.