Optical fiber coating die with reduced wetted length

Patent metadata

Field	Value
Publication number	US-11440839-B2
Application number	US-202017112166-A
Country	US
Kind code	B2
Filing date	Dec 4, 2020
Priority date	Jan 24, 2017
Publication date	Sep 13, 2022
Grant date	Sep 13, 2022

Abstract

An optical fiber coating apparatus that provides increased gyre stability and reduced gyre strength, thereby providing a more reliable coating application process during fiber drawing includes a cone-only coating die having a conical entrance portion with a tapered wall angled at a half angle α, wherein 2°≤α≤25°, and a cone height L1 less than 2.2 mm, and a cylindrical portion having an inner diameter of d2, wherein 0.1 mm≤d2≤0.5 mm and a cylindrical height of L2, wherein 0.05 mm≤L2≤1.25 mm; a guide die having an optical fiber exit, the guide die disposed adjacent the cone-only coating die such that a wetted length (L5) between the optical fiber exit of the guide die and the entrance of the cone-only coating die is from 1 mm to 5 mm; and a holder for holding the cone-only coating die and the guide die in a fixed relationship defining a coating chamber between the guide die and the cone-only coating die, the coating chamber having an inner radius L6 from the optical fiber axis to an inner wall of the holder that is from 3 mm to 10 mm.

First claim

What is claimed is:

1. A process of coating an optical fiber during a fiber draw process wherein the optical fiber is drawn at a draw speed V d , and the process of coating the optical fiber, comprises:
passing the drawn optical fiber through a guide die and thereafter through a cone-only coating die,
the cone-only coating die having a wall temperature T die and a conical entrance with a tapered wall angled at a half angle α, wherein 2°≤α≤25°, and a cone height L 1 less than 2.2 mm, and a cylindrical portion having an inner diameter of d 2 , wherein 0.1≤d 2 ≤0.5 mm, and a cylindrical height of L 2 , wherein 0.05≤L 2 ≤1.25 mm,
the guide die having an optical fiber exit, the guide die disposed adjacent the cone-only coating die such that a wetted length L 5 between the optical fiber exit of the guide die and the conical entrance of the cone-only coating die is less than 4.5 mm,
the cone-only coating die and the guide die being held in a fixed relationship by a holder to define a coating chamber between the guide die and the cone-only coating die, the coating chamber having an inner radius L 6 from the optical fiber to an inner wall of the holder that is from 3 mm to 10 mm, the coating chamber holding a liquid coating composition that is entrained on a surface of the optical fiber as it is drawn through the cone-only coating die resulting in coating thickness of d coat on the surface of the optical fiber.

2. The process of claim 1 , wherein the wetted length L 5 is less than 3.5 mm.

3. The process of claim 1 , wherein the inner radius L 6 of the coating chamber is from 6 mm to 10 mm.

4. The process of claim 1 , wherein the cone height L 1 is between 0.25 mm and 2.0 mm.

5. The process of claim 1 , wherein the draw speed V d is larger than 45 m/s.

6. The process of claim 1 , wherein the draw speed V d is larger than 60 m/s.

7. The process of claim 1 , wherein a ratio of wetted length L 5 to draw speed V d is between 0.01 msec to 0.15 msec.

8. The process of claim 7 , wherein the ratio of wetted length L 5 to draw speed V d is between 0.025 msec to 0.125 msec.

9. The process of claim 1 , wherein the thickness of the liquid coating composition on the surface of the optical fiber d coat is between 2 microns and 50 microns.

10. The process of claim 1 , wherein the liquid coating composition that is entrained on a surface of the optical fiber is a UV curable acrylate composition and is cured using a light emitting diode UV source having an emission spectrum with a peak wavelength in the range between 300 nm-450 nm.

11. The process of claim 1 , wherein the cone-only coating die is a primary coating die and the liquid coating composition that is entrained on a surface of the optical fiber is a primary coating and the thickness of the liquid primary coating composition on the surface of the optical fiber d coat is between 10 microns and 50 microns.

12. The process of claim 1 , wherein the cone-only coating die is a secondary coating die and the liquid coating composition that is entrained on a surface of the optical fiber is a secondary coating and the thickness of the liquid secondary coating composition on the surface of the optical fiber d coat is between 10 microns and 50 microns.

13. The process of claim 1 , wherein the cone-only coating die has a lubrication pressure that is less than 500 psi.

14. The process of claim 1 , wherein a gyre is formed in the coating chamber having a maximum temperature of less than 175° C.

15. The process of claim 14 , wherein the maximum temperature of the gyre is less than 100° C.

Assignees

• Corning Inc

Inventors

• De Sumitava
• Moore Robert Clark
• Neilson Douglas Gregg
• Tandon Pushkar

Classifications

• C03C25/105 Primary

  Organic claddings · CPC title

• C03C25/285

  Acrylic resins · CPC title

• C03C25/18 Primary

  Extrusion · CPC title

• C03C25/1065

  Multiple coatings · CPC title