Coated optical fibers having strippable primary coatings and processes for making and using same

• US 6,014,488 A
• Filed: 09/01/1998
• Issued: 01/11/2000
• Est. Priority Date: 01/24/1997
• Status: Expired due to Term

• Current Assignee: Hexion Incorporated (Hexion Intermediate Holding 2, Inc.)
• Original Assignee: Borden Chemical, Inc.
• Inventors: Shustack, Paul J.
• Primary Examiner(s): Ullah, Akm E.
• Application Number:
  US09/142,102
• Time in Patent Office: 497 Days
• Field of Search: 385/128-130, 385/141, 385/147, 385/145, 385/103, 385/106, 385/109, 65/435, 65/425, 65/432, 522/180, 522/181, 428/378, 427/163.2, 427/165, 427/302, 427/377, 427/385.5, 427/407.1, 528/307, 528/376
• US Class Current: 385/128
• CPC Class Codes: C03C 25/106 Single coatings
• CPC Class Codes: C03C 25/1065 Multiple coatings
• CPC Class Codes: G02B 6/02395 Glass optical fibre with a protective coating, e.g. two layer polymer coating deposited directly on a silica cladding surface during fibre manufacture G02B6/02052, G02B6/02057, G02B6/024, G02B6/032, G02B6/105, G02B6/14 take precedence; coating on fibre gratings G02B6/02104; multilayer core or cladding G02B6/036; reinforcing splice joints G02B6/2558; optical cables, i.e. comprising protective structures external to the protective coating such as a jacket or plural coated optical fibres G02B6/44; coating of glass to obtain optical fibres C03C25/104
• CPC Class Codes: G02B 6/245 Removing protective coverings of light guides before coupling
• CPC Class Codes: Y10T 428/2938 Coating on discrete and individual rods, strands or filaments

Abstract

The invention relates to coated optical fibers which are coated with a particular radiation-cured primary coating layer composition. The fibers which are coated comprises a glass core and a glass cladding layer. The core, for example may comprises silica doped with oxides of germanium or phosphorous and the cladding, a pure or doped silicate such as fluorosilicate. Alternatively, the fibers may comprises a polymerclad silica glass core. Examples of such claddings include organosiloxanes such as polydimethylsiloxane or a fluorinated acrylic polymer.

Claims

1. A coated optical fiber comprising:

an optical fiber; and

a cured primary coating on the optical fiber

wherein the primary coating is strippable from a portion of the optical fiber at a temperature in at least a portion of the temperature range from about 40°

to about 200°

C. by exerting a force to a portion of the primary coating about the portion of optical fiber in a direction parallel to the longitudinal axis of the glass fiber which is away from a portion of the primary coating remaining on the optical fiber, such that the exertion of force, followed by an optional one wipe with an alcohol laden piece of cloth or paper of the stripped portion of optical fiber, results in the stripped portion of optical fiber having substantially no residue of the primary coating as observable by a 2 power magnification.

2. The coated optical fiber of claim 1, wherein the primary coating is strippable at the temperature upon execution of the force to leave a ratio of less than 20 particles visible at a 2×

magnification per 30 millimeters of stripped length.

3. The coated optical fiber of claim 2, wherein the primary coating is strippable at the temperature upon exertion of the force to leave a ratio of no particles visible at a 2×

magnification per 30 millimeters of stripped length.

4. The coated optical fiber of claim 1, wherein the coating prior to curing has a freeze point of at most about 60°

C.

5. The coated optical fiber of claim 4, wherein the freeze point is at most about 25°

C.

6. The coated optical fiber of claim 4, wherein the freeze point is in the range from about 0°

C. to about 60°

C.

7. The coated optical fiber of claim 6, wherein the freeze point is in the range from about 5°

C. to about 25°

C.

8. The coated optical fiber of claim 1, wherein the primary coating is made of a material which is removable from a glass substrate by a peel force of less than 50 grams of force, as measured by a 180°

peel back test at 50% relative humidity and room temperature, has an elongation to break of at least about 75% as measured by ASTM D-882, and has a tensile strength of at least about 80 psi as measured by ASTM D-882.

9. The coated optical fiber of claim 8, wherein the peel force is less than 20 grams of force.

10. The coated optical fiber of claim 9, wherein the peel force is less than 15 grams of force.

11. The coated optical fiber of claim 10, wherein the peel force is from about 5 to about 15 grams of force.

12. The coated optical fiber of claim 8, wherein the elongation to break is at least about 90%.

13. The coated optical fiber of claim 8, wherein the elongation to break is at least 100%.

14. The coated optical fiber of claim 8, wherein the elongation to break is about 100 to about 150%.

15. The coated optical fiber of claim 8, wherein the tensile strength is at least about 100 psi.

16. The coated optical fiber of claim 15, wherein the tensile strength is at least about 120 psi.

17. The coated optical fiber of claim 15, wherein the tensile strength is from about 120 to about 300 psi.

18. The coated optical fiber of claim 1, wherein said primary coating layer comprises a cured reaction product of from about 10 to about 80 percent by weight of one or more acrylate- or methacrylate-terminated urethane oligomers.

19. The coated optical fiber of claim 18, wherein said primary coating layer (b) further comprises the reaction product of, in addition to the acrylate or methacrylate-terminated oligomer from about 10 to about 75 percent by weight of one or more monomer diluents selected from the group consisting of:

(i) alkyl acrylate and alkyl methacrylate monomers having 6 to 18 carbon atoms in the alkyl moiety;

(ii) monomers having (i) an aromatic moiety, (2) a moiety containing acrylic or methacrylic unsaturation, and (3) a hydrocarbon moiety; and

(iii) mixtures thereof.

20. The coated optical fiber of claim 18, wherein said monomer diluent is selected from the group consisting of hexyl acrylate;

hexylmethacrylate;

ethylhexyl acrylate;

ethylhexylmethacrylate;

isooctyl acrylate;

isooctyl methacrylate;

octyl acrylate;

octyl methacrylate;

decyl acrylate;

decyl methacrylate;

isodecyl acrylate, isodecyl methacrylate;

lauryl acrylate;

lauryl methacrylate;

tridecyl acrylate;

tridecyl methacrylate;

palmitic acrylate;

palmitic methacrylate;

myristyl acrylate;

myristyl methacrylate;

cetyl acrylate;

cetyl methacrylate;

2-propenoic acid, 2-(((butyl)amino)carbonyloxy)ethylester, N-vinyl caprolactam;

stearyl acrylate;

stearyl methacrylate;

C14-C15 hydrocarbon diol diacrylates;

C14-C15 hydrocarbon diol dimethacrylates;

phenoxyalkyl acrylate;

phenoxyalkyl methacrylate;

phenoxyalkyl alkoxylate acrylate;

phenoxyalkyl alkoxylate methacrylate;

para-cumylphenol ethoxylated acrylate, para-cumylphenol ethoxylated methacrylate;

3-acryloyloxypropyl-2-N-phenylcarbamate;

isobornyl acrylate;

isobornyl methacrylate, dicyclopentenylacrylate;

dicyclopentenylmethacrylate;

dicyclopentenyl ethoxylate acrylate;

dicyclopentenyl ethoxylate methacrylate;

tetrahydrofurfuryl acrylate;

tetrahydrofurfuryl methacrylate;

polyalkylene glycol nonylphenylether acrylates;

polyalkylene glycol nonylphenylether methacrylates;

caprolactone acrylate; and

mixtures thereof.

21. The coated optical fiber of claim 18 wherein said primary coating layer additionally comprises from about 0.1 to about 3.0 percent by weight of an organofunctional silane adhesion promoter.

22. The coated optical fiber of claim 21, wherein said adhesion promoter is selected from the group consisting of acrylate-functional silanes;

amino-functional silanes;

mercapto-functional silanes;

methacrylate-functional silanes;

acrylamidofunctional silanes;

alkyl-functional silanes;

vinyl-functional silanes; and

mixtures thereof.

23. The coated optical fiber of claim 21, wherein said adhesion promoter is selected from the group consisting of 3-acryloxypropyltrimethoxy-silane, 3-aminopropyltriethoxysilane, 3-methacryloxypropyl-trimethoxy silane, 3-mercaptopropyltrimethoxysilane and 3-mercaptopropyltriethoxy silane, and mixtures thereof.

24. The coated optical fiber of claim 18, wherein said primary coating layer additionally comprises a photoinitiator.

25. The coated optical fiber of claim 18, wherein said primary coating layer additionally comprises from about 0.0001 to about 3.0 percent by weight of a stabilizer selected from the group consisting of organic phosphates;

silanes;

hindered phenols;

amines and mixtures thereof.

26. The coated optical fiber of claim 1, wherein the primary coating comprises the radiation-cured reaction product of the following ingredients:

(A) from about 10 percent to about 90 percent by weight of a reactively terminated urethane oligomer which is the reaction product of (i) at least one polyol selected from the group consisting of poyether polyols, hydrocarbon polyols, polycarbonate polyols, and polyisocyanate polyols;

(ii) a wholly aliphatic polyisocyanate; and

(iii) an endcapping monomer supplying a reactive terminus;

(B) from about 5 percent to about 80 percent by weight of a monomer diluent which is terminated with at least one end group capable of reacting with the reactive terminus of (A);

(C) from about 0 percent to about 10 percent by weight of a photoinitiator; and

(D) from about 0 to about 3 percent by weight of an organofunctional silane adhesion promoter which binds in with the primary coating composition during cure;

wherein all of the stated percentages are percentages by weight based on the total weight of (A), (B), (C) and (D), wherein the tensile modulus of the coating composition, when cured, is less about 500 psi at 25°

C., and wherein the refractive index of the cured coating composition is at least 1.48.

27. The coated optical fiber of claim 1, wherein the primary coating comprising the radiation-cured reaction product of the following ingredients:

(1) from about 10 to about 80 percent by weight of one or more acrylate- or methacrylate-terminated aliphatic polyether urethane oligomers;

(2) from about 10 to about 75 percent by weight of one or more monomer diluents;

(3) from about 0 to about 10 percent by weight of a photoinitiator; and

(4) from about 0 to about 3 percent by weight of an organofunctional silane adhesion promoter which binds in with the primary coating composition during cure;

all of said percentages being percentages by weight based on the weight of all said ingredients.

28. The coated optical fiber of claim 27, wherein the oligomer and the one or more monomer diluents are selected such that a mixture of the oligomer and the one or more monomer diluents is liquid at 5 to 25°

C.

29. The coated optical fiber of claim 1, wherein the primary coating comprises a cured mixture of an aliphatic polyether urethane acrylate oligomer, a monomer selected from the group consisting of lauryl acrylate, or nonylphenol ethoxy acrylate, a photoinitiator selected from the group consisting of hydroxyclohexylphenyl ketone, an antioxidant selected from the group consisting of thiodiethylene bis(3,5-di-tert-butyl-4-hydroxy hydrocinnamate), a chain transfer agent selected from the group consisting of isooctyl-3-mercaptopropionate, less than 5 weight percent, based or mixture weight, of a silane coupling agent selected from the group consisting of 3-mercaptopropyl trimethoxy silane, and a stabilizer selected from the group consisting of 3-aminopropyl trimethoxy silane.

30. An optical ribbon comprising a plurality of optical fibers of claim 1 and a matrix material, the plurality of fibers held together in a parallel arrangement by the matrix material.

37. The fiber of claim 8, wherein the elongation to break for the primary coating is about 80%.

31. A method of preparing a coated optical fiber for splicing, the coated optical fiber comprising a primary coating coated onto an optical fiber, comprising the steps of:

stripping the primary coating away from a portion of the optical fiber at a temperature in at least a portion of the temperature range from about 40°

to about 200°

C. by cutting with a blade into the primary coating, then having the blade exert a force on the primary coating in a direction parallel to the optical fiber to force the primary coating away from the portion of the optical fiber, and optionally wiping the portion of optical fiber from which primary coating has been forced away with an alcohol laden piece of cloth or paper, such that the stripped portion exhibits a ratio of little or no residue of the primary coating as observable under a 2 power magnification per 30 millimeter length of stripped portion.

32. A method of splicing coated optical fibers comprising, preparing two optical fibers for splicing according to the method of claim 31;

aligning the stripped portions of the prepared optical fibers; and

joining the stripped portions of the prepared optical fibers.

33. A spliced optic fiber made by the method of claim 32.

34. A coated optical fiber comprising:

an optical fiber;

a primary coating coated onto the optical fiber, the primary coating made of a material which is removable from a glass substrate by a peel force of less than 50 grams of force, as measured by a 180°

peel back test at 50% relative humidity and room temperature, an elongation to break of at least about 75% as measured by ASTM D-882, and a tensile strength of at least about 80 psi as measured by ASTM D-882.

38. The fiber of claim 34, wherein the elongation to break for the primary coating is about 80%.

35. A process for preparing a coated optical fiber comprising

(1) applying to an optical fiber a primary coating composition layer comprising a mixture of the following ingredients:

(A) from about 10 percent to about 90 percent by weight of a reactively terminated urethane oligomer which is the reaction product of (i) at least one polyol selected from the group consisting of poyether polyols, hydrocarbon polyols, polycarbonate polyols, and polyisocyanate polyols;

(ii) a wholly aliphatic polyisocyanate; and

(iii) an endcapping monomer supplying a reactive terminus;

(B) from about 5 percent to about 80 percent by weight of a monomer diluent which is terminated with at least one end group capable of reacting with the reactive terminus of (A);

(C) from about 0 percent to about 10 percent by weight of a photoinitiator; and

(D) from about 0 to about 3 percent by weight of an organofunctional silane adhesion promoter which binds in with the primary coating composition during cure;

wherein all of the stated percentages are percentages by weight based on the total weight of (A), (B), (C) and (D), wherein the tensile modulus of the coating composition, when cured, is less about 500 psi at 25°

C., and wherein

the refractive index of the cured coating composition is at least 1.48; and

(2) radiation-curing said coating in situ,

wherein the primary coating is strippable from a portion of the optical fiber at a temperature in at least a portion of the temperature range from about 40°

to about 200°

C. by exerting a force to a portion of the primary coating about the portion of optical fiber in a direction parallel to the longitudinal axis of the glass fiber which is away from a portion of the primary coating remaining on the optical fiber, such that the exertion of force followed by an optional one wipe, with an alcohol laded piece of cloth or paper of the stripped portion of optical fiber, results in the stripped portion of optical fiber having a ratio of substantially no residue of the primary coating as observable by a 2 power magnification per 30 millimeter length of the stripped portion.

36. The process of claim 35, wherein said mixture comprises:

(i) from about 10 to about 80 percent by weight of one or more acrylate- or methacrylate-terminated urethane oligomers;

(ii) from about 10 to about 75 percent by weight of one or more monomer diluents;

(iii) from about 0 to about 10 percent by weight of the photoinitiator; and

(iv) from about 0 to about 3 percent by weight of the organofunctional silane adhesion promoter which binds in with the primary coating composition during cure, all of said percentages being percentages by weight based on the weight of all said ingredients.