Semi-Tight Optical Fiber Unit

• US 20090010602A1
• Filed: 12/21/2007
• Published: 01/08/2009
• Est. Priority Date: 12/21/2006
• Status: Active Grant

• Current Assignee: Draka-Comteq USA Incorporated (Draka-Comteq)
• Original Assignee: Draka-Comteq USA Incorporated (Draka-Comteq)
• Inventors: Marie Berkers, Arnoldus Gertrudis Wilhelmus, Nothofer, Klaus, Huijsman, Dick
• Granted Patent: US 7,742,668 B2
• Time in Patent Office: Days
• US Class Current: 385/109
• CPC Class Codes: G02B 6/4402 with one single optical waveguide G02B6/4429, G02B6/4439, G02B6/4479 take precedence
• CPC Class Codes: G02B 6/4438 for facilitating insertion by fluid drag in ducts or capillaries
• CPC Class Codes: G02B 6/44384 the means comprising water blocking or hydrophobic materials G02B6/4439, G02B6/4479 take precedence

Abstract

Disclosed is a dry, semi-tight optical fiber unit that includes one or more optical fibers positioned within a buffer tube. A protective coating is provided upon the surface of the optical fibers, and an anti-adhesive coating is substantially bonded to the protective coating. One or more of these optical fiber units may be included in an optical cable. Also disclosed is a method for efficiently producing such an optical fiber unit.

Claims

1. An optical fiber unit, comprising:

an optical fiber including a central glass fiber surrounded by a protective coating;

an anti-adhesive coating surrounding said optical fiber, said anti-adhesive coating being at least partially bonded to said protective coating of said optical fiber; and

a buffer tube surrounding said optical fiber and said anti-adhesive coating to define a radial intermediate space between said anti-adhesive coating and said buffer tube;

wherein said anti-adhesive coating and said buffer tube are separated by an average radial clearance of at least about three microns; and

wherein neither grease nor gel-like material is present within the radial intermediate space between said anti-adhesive coating and said buffer tube.

2. An optical fiber unit according to claim 1, wherein said buffer tube surrounds a plurality of optical fibers to define a radial intermediate space between (i) said plurality of optical fibers and any anti-adhesive coating surrounding one or more of said optical fibers and (ii) said buffer tube.

3. An optical fiber unit according to claim 2, wherein each optical fiber is surrounded by an anti-adhesive coating and wherein said plurality of optical fibers together with said anti-adhesive coatings can be positioned within said buffer tube to provide an average radial clearance of at least about 100 microns with respect to the buffer tube.

4. An optical fiber unit according to claim 1, further comprising a super-absorbent polymer that is present in the radial intermediate space between said anti-adhesive coating and said buffer tube.

5. An optical fiber unit according to claim 1, wherein said anti-adhesive coating comprises a UV-curable resin.

6. An optical fiber unit according to claim 5, wherein said anti-adhesive coating comprises reactive silicone groups.

7. An optical fiber unit according to claim 1, wherein said anti-adhesive coating comprises pigments and/or colorants.

8. An optical fiber unit according to claim 1, wherein said anti-adhesive coating surrounding said optical fiber is between about one and ten microns thick.

9. An optical fiber unit according to claim 1, wherein said buffer tube comprises thermoplastic elastomer having flexible diol segments.

10. An optical cable comprising a sheath that surrounds one or more optical fiber units according to claim 1.

11. An optical cable, comprising a dimensionally stable tube that surrounds one or more optical fiber units according to claim 1, said optical fiber units being freely positioned with said dimensionally stable tube, and an outer jacket surrounding said dimensionally stable tube.

12. An optical cable according to claim 11, further comprising a central strengthening element around which said dimensionally stable tube is wound.

13. A dry, semi-tight optical fiber unit that is free of greases or gels, comprising:

an optical fiber having a central glass fiber surrounded by a protective coating;

an anti-adhesive coating surrounding said optical fiber, said anti-adhesive coating being substantially bonded to said protective coating of said optical fiber; and

a buffer tube surrounding said optical fiber and said anti-adhesive coating, the average radial clearance between said anti-adhesive coating and said buffer tube being between about three microns and 100 microns.

14. An optical fiber unit according to claim 13, further comprising a dry super-absorbent polymer that is present within said buffer tube between said anti-adhesive coating and said buffer tube.

15. An optical fiber unit according to claim 13, wherein no more than one optical fiber is present within said buffer tube.

16. An optical fiber unit according to claim 15, wherein said anti-adhesive coating surrounding said optical fiber is between about one and ten microns thick.

17. A method for making an optical fiber unit, comprising:

providing an optical fiber having a central glass fiber surrounded by a protective coating;

applying an anti-adhesive coating to the optical fiber'"'"'s protective coating; and

thereafter extruding a buffer tube around the optical fiber and the anti-adhesive coating to define an intermediate radial space between the anti-adhesive coating and the buffer tube, the intermediate radial space defining an average radial separation of at least about three microns between the anti-adhesive coating and the buffer tube.

18. A method according to claim 17, wherein the step of applying an anti-adhesive coating to the optical fiber'"'"'s protective coating comprises passing the optical fiber through a liquid anti-adhesive and then curing the applied, liquid anti-adhesive on the optical fiber to thereby form the anti-adhesive coating.

19. A method according to claim 18, wherein the step of curing the applied, liquid anti-adhesive on the optical fiber comprises irradiating the liquid anti-adhesive with UV radiation.

20. A method according to claim 17, wherein:

the step of providing an optical fiber comprises providing a plurality of optical fibers, each optical fiber having a central glass fiber surrounded by a protective coating;

the step of applying an anti-adhesive coating to the optical fiber'"'"'s protective coating comprises applying an anti-adhesive coating to each optical fiber'"'"'s protective coating; and

the step of extruding a buffer tube around the optical fiber and the anti-adhesive coating comprises loosely extruding a buffer tube around the plurality of optical fibers as coated with the anti-adhesive coating, the extrusion of the buffer tube providing a sufficient annular space around the plurality of optical fibers such that the plurality of optical fibers with their respective anti-adhesive coatings can aggregated within the buffer tube to provide average radial separation of at least about 100 microns from the buffer tube'"'"'s inner surface.