WO2014088926A1

WO2014088926A1 - D1530 radiation curable primary coatings for optical fiber

Info

Publication number: WO2014088926A1
Application number: PCT/US2013/072549
Authority: WO
Inventors: Wendell Wayne Cattron
Original assignee: DSM IP Assets BV
Current assignee: DSM IP Assets BV
Priority date: 2012-12-03
Filing date: 2013-12-02
Publication date: 2014-06-12
Anticipated expiration: 2015-06-03

Abstract

A radiation curable Primary Coating composition is described and claimed. The radiation curable primary coating comprises at least two diluent monomers; wherein the first diluent monomer contains a polar segment and a non-polar segment; is monofunctional; is lipophilic, such that the HLB value is less than about 10; and is present in the composition at about 20 wt.% to about 60 wt.%; and wherein the second diluent monomer contains a polar segment and a non-polar segment; is multifunctional; is hydrophilic, such that the HLB value is greater than about 10; and is present in the composition at from about 0.5 wt.% to about 20 wt.%.

Description

D1530 Radiation Curable Primary Coatings for Optical Fiber

FIELD OF THE INVENTION

[0001 ] The present invention relates to radiation curable primary coatings for optical fibers, optical fibers coated with said coatings and methods for the preparation of coated optical fibers.

BACKGROUND OF THE INVENTION

[0002] An optical fiber is a flexible, transparent fiber made of glass (silica) or plastic, slightly thicker than a human hair. It functions as a waveguide, or "light pipe", to transmit light between the two ends of the fiber. Optical fibers are widely used in fiber-optic communications, which permits transmission over longer distances and at higher bandwidths (data rates) than other forms of communication. Optical Fibers are used instead of metal wires because signals travel along them with less loss and are also immune to electromagnetic interference.

[0003] Optical fibers typically include a transparent core surrounded by a transparent cladding material with a lower index of refraction. Light is kept in the core by total internal reflection. This causes the fiber to act as a waveguide. Fibers that are capable of having more than one light signal travel along them simultaneously (otherwise known as being able to support many propagation paths or transverse modes) are called multi-mode fibers ("MMF"), while those optical fibers that are capable of having only one light signal travel along them (otherwise known as supporting only a single mode) are called single-mode fibers ("SMF"). Multi-mode fibers generally have a wider core diameter of from about 50 microns to about 63 microns core diameter. In comparison single-mode fibers have a core diameter of from about 8 microns to about 10.

[0004] MMF are typically used for short-distance communication links and for applications where high power must be transmitted. One current location where MMF are typically used is at data centers, where huge amounts of data have to be processed. In contrast to MMF, SMF are used for most communication links longer than 1 050 meters (3,440 ft.). [0005] Both single mode and multi-mode optical fibers are typically coated with two or more radiation curable coatings known as a "dual-layer" coating approach. These coatings are typically applied to the optical fiber in liquid form, and then exposed to radiation to effect curing. The type of radiation that may be used to cure the coatings should be that which is capable of initiating the polymerization of one or more radiation curable components of such coatings. Radiation suitable for curing such coatings is well known, and includes ultraviolet light (hereinafter "UV") and electron beam ("EB"). The preferred type of radiation for curing coatings used in the preparation of coated optical fiber is UV.

[0006] The inner primary coating is the coating which directly contacts the optical fiber and it is also referred to as just the Primary Coating, and the coating that covers the Primary Coating is called the Outer Primary Coating, Outer Secondary Coating or just the Secondary Coating. The inner primary coating is designed to act as a shock absorber to minimize attenuation caused by microbending. The outer secondary coating protects the primary coating against mechanical damage and acts as a barrier to lateral forces. It is known in the art of radiation curable coatings for optical fibers that Primary Coatings are advantageously softer than Secondary Coatings. One advantage of the softness of the Primary Coating is that this coating enhances the flexibility of the fragile Optical Fiber.

[0007] These fiber optic coating layers are applied during the fiber draw, at speeds approaching 2400 meters per minute = 144 kilometers per hour = 89 miles per hour for manufacturing of single-mode Optical Fibers and at speeds approaching 1000 meters per minute = 60 kilometers per hour = 37 miles per hour for manufacturing of multi-mode optical fiber. Fiber optic coatings are applied using one of two methods: wet-on-dry and wet-on-wet. In wet-on-dry, the fiber passes through a primary coating applicator, which is then UV cured - then through the secondary coating applicator, which is subsequently cured. In wet-on-wet, the fiber passes through both the primary coating application and the secondary coating applicator, and then passes through UV curing.

[0008] Fiber optic coatings are applied in concentric layers to prevent damage to the fiber during the drawing application and to maximize fiber strength and microbending resistance. Unevenly coated fiber will experience non-uniform forces when the coating expands or contracts, and is susceptible to greater signal attenuation. Under proper drawing and coating processes, the coatings are concentric around the fiber, continuous over the length of the application and have constant thickness.

[0009] Fiber optic coatings protect the glass fibers from scratches that could lead to strength degradation. The combination of moisture and scratches accelerates the aging and deterioration of fiber strength. When fiber is subjected to low stresses over a long period, fiber fatigue can occur as evidence by microbending. Over time or in extreme conditions, these factors combine to cause microscopic flaws in the glass fiber to propagate, which can ultimately result in microbending induces attenuation which is evidence of fiber failure, [00010] Microbends are sharp but microscopic curvatures in an optical fiber involving local axial displacements of a few micrometers and spatial wavelengths of a few millimeters. Microbends can be induced by thermal stresses and/or mechanical lateral forces. When present, microbends attenuate the signal transmission capabil ity of the coated optical fiber. Attenuation is the undesirable reduction of signal carried by the optical fiber.

[0010] It would be desirable to develop a next generation, robust, low microbending optical fiber primary coating, wherein this optical fiber primary coating is suitable for both single mode and multi-mode optical fiber.

SUMMARY OF THE INVENTION

[001 1] The first aspect of the instant claimed invention is a radiation curable Primary Coating composition comprising

(a) at least one urethane (meth)acrylate functional oligomer;

(b) at least one photoinitiator,

(c) at least two diluent monomers;

wherein the first diluent monomer

(i) contains a polar segment and a non-polar segment;

(ii) is monofunctional;

(iii) is more non-polar than polar, meaning it is lipophilic, such that the HLB value is less than about 10; (iv) is present in the composition at about 20 wt.% to about 60 wt.%; and

wherein the second diluent monomer

(v) contains a polar segment and a non-polar segment;

(vi) is multifunctional;

(vii) is more polar than non-polar, meaning it is hydrophilic, such that the HLB value is greater than about 10; and

(viii) is present in the composition at from about 0.5 wt.% to about 20 wt.%.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0012] The first aspect of the instant claimed invention is a radiation curable Primary Coating composition comprising

(a) at least one urethane (meth)acrylate functional ol igomer;

(b) at least one photoinitiator,

(c) at least two diluent monomers;

wherein the first diluent monomer

(i) contains a polar segment and a non-polar segment;

(ii) is monofunctional;

(iii) is more non-polar than polar, meaning it is lipophilic, such that the HLB value is less than about 10;

(iv) is present in the composition at about 20 wt.% to about 60 wt.%; and

wherein the second diluent monomer is

(v) contains a polar segment and a non-polar segment;

(vi) is multifunctional;

(viii) is present in the composition at from about 0.5 wt.% to about 20 wt.%.

[0013] Multifunctional as used in this patent application means difunctional or greater. It does not include monofunctional. [0014] In the instant claimed invention, it is critical that the selection of the diluent monomers includes a first diluent monomer, wherein the first diluent monomer is monofunctional and lipophilic and includes a second diluent monomer, wherein the second di luent monomer is multifunctional and is hydrophilic.

[0015] By way of definitions, a "lipophile", is a molecule that is attracted to, and tends to be dissolved in oils. In contrast, a "hydrophile", is a molecule or other molecular entity that is attracted to, and tends to be dissolved by, water. A hydrophilic molecule or portion of a molecule is one that has a tendency to interact with or be dissolved by water and other polar substances. A hydrophobic moiety, in contrast is not attracted to and does not dissolve in water.

[0016] It is understood that both of these diluent monomers act as surfactants in the radiation curable coatings. Chemically speaking, "surfactants" are usually organic compounds that are amphophilic, meaning they contain both hydrophobic groups and hydrophilic groups. Put another way, a surfactant combines both hydrophilic and hydrophobic parts into one molecule and is known to induce an order into a system which is exhibited by a phase separation of a hydrophilic region and a hydrophobic region.

Surfactants are used to make emulsions or water in oil emulsions or oil in water emulsions and form micelles.

[001 7] Ethoxylated nonyl phenol acrylate is a known diluent monomer and is commercially available, as SR-504, from Sartomer or as AgiSyn® 2895 available from

AGI-DSM Corporation. Ethoxylated nonyl phenol acrylate has long been used in radiation curable coatings for optical fiber as a diluent monomer. Ethoxylated nonyl phenol acrylate is made from a surfactant, ethoxylated nonyl phenol . The acrylate portion of ethoxylated nonyl phenol acrylate must be connected to the polar part of ethoxylated nonyl phenol, through the -OH group which is at the polar end of the ethoxylated nonyl phenol.

Ethoxylated nonyl phenol acrylate a very polar, monofunctional acrylate diluent monomer that acts like a surfactant in the radiation curable primary coating compositions of the instant claimed invention. [0018] When the first diluent monomer used in a radiation curable primary coating is a very polar monofimctional acrylate, such as ethoxylated nonyl phenol acrylate, it is believed, without intending to be bound thereby, that this type of chemistry causes the crosslinks to form first in the more polar regions of the coating where the acrylate groups are. This is where the cure speed of the radiation curable coating is faster as compared to the non-polar regions of the coating where the cure speed is slower because the

concentrations of acrylate groups are less there.

[0019] The use of ethoxylated nonyl phenol acrylate in a primary coating, along with a second diluent monomer, where the second diluent monomer is both multifunctional and hydrophilic, provides hitherto unequaled performance where a sufficiently fast cure speed is achieved that allows for the complete formation of in-situ modulus, in-situ T_g and %RAU, even when the fiber is being drawn at speeds of from about 600 meters per minute to about 2400 meters per minute. This specific combination of diluent monomers also limits the amount of "post-cure" increase in modulus, so common in the field of existing "legacy" radiation curable optical fiber primary coatings. "Legacy" coatings are considered pre-Supercoatings, see US Patent Number 8,426,020, "D 1381 Supercoatings for Optical Fiber". Legacy coatings are formulated such that they are not capable of curing fast enough over a line speed of from about 600 meters per minute to about 2400 meters per minute and still have sufficient formation of in-situ modulus, in-situ Tg and %RAU.

[0020] Further to the discussion of chemistry, this is believed, without intending to be bound thereby, because the acrylate groups in the highly polar acrylate diluent monomer are positioned via phase separation to be concentrated into the polar region of the coating. With them positioned in the polar region of the coating the curing reaction is facilitated.

[0021] In contrast to the phase separation concentration of the acrylate groups in the polar region of the coating, this concentration does not take place with other normal, non- surfactant type diluent monomers, which means the cure speed of coatings using those "non-surfactant" type is typically lower. The lower the cure speed, the lower the modulus on the fiber as well. This is undesirable. [0022] Put another way, with a low cure speed, the coating is not fully cured as the optical fiber leaves the UV curing region of the draw tower. Thus the physical properties of in-situ modulus, T_g and %RAU are not fully developed. These properties then continue to develop as "post curing" takes place with time. Post curing development of in-situ modulus is very bad for the performance of the fiber as it is known to lead to microbending induced attenuation of the light signal.

[0023] It is known in the art of radiation curable coatings for optical fiber that a relatively fast cure speed is needed to obtain a highly cured film. The combination of highly polar, acrylate functionality in the first diluent monomer and multifunctional lipophilic functionality in the second diluent monomer means there should be little or no unreacted acrylate groups. Not having unreacted acrylate groups is a good thing. This is a good thing, because with no unreacted acrylate groups there will be limited or no increase in in-situ modulus over time. With limited or no increase in in-situ modulus over time, microbending induced attenuation of the fiber will remain low.

[0024] The Hydrophilic-Lipophilic Balance (abbreviated HLB) of a moiety is a measure of the degree to which it is hydrophilic or lipophilic, determined by calculating values for the different regions of the molecule, as described by Griffin in Griffin WC: "Classification of Surface-Active Agents by 'HLB,'" Journal of the Society of Cosmetic Chemists 1 949, i, 3 1 1 , and Griffin WC: "Calculation of HLB Values of Non-Ionic Surfactants," Journal of the Society of Cosmetic Chemists 1945, 5, 249.

[0025] Griffin's method of calculating HLB values for moieties as described in 1954 works as follows: HLB = 20 x Mh / M

where Mh is the molecular mass of the hydrophilic portion of the molecule, and M is the molecular mass of the whole molecule, giving a result on a scale of 0 to 20. An HLB value of 0 corresponds to a completely lipophilic/hydrophobic molecule, and a value of 20 corresponds to a completely hydrophilic/lipophobic molecule.

The HLB value can be used to predict the properties of a moiety:

A value < 10 : lipid soluble (water insoluble);

A value > 10 : water soluble (lipid insoluble); A value from 4 to 8 indicates an anti-foaming agent;

A value from 7 to 1 1 indicates a W/O (water in oil) emulsifier;

A value from 12 to 16 indicates O/W (oil in water) emulsifier;

A value from 1 1 to 14 indicates a wetting agent;

A value from 12 to 15 indicates a detergent; and

A value of 16 to 20 indicates a solubilizer or hydrotrope.

[0026] For the instant claimed invention, the first diluent monomer is more non-polar than polar, such that the HLB value is less than about 10; and the second diluent monomer is hydrophilic, such that the HLB value is greater than about 10,

[0027] Other methods of determining the HLB value of a diluent monomer are described in references such as "Handbook of Detergents", © 1999 by Marcel Dekker, Inc., Part A Properties, edited by Guy Broze. On Page 3 1 the section on B. Ethers, subsection 1 . Alkoxylated Alcohols describes ethoxylated alcohols which are produced from the reaction of fatty alcohols with ethylene oxide (EO). On page 3 1 the following text occurs: The water solubility of EO derivatives essentially depends on both the temperature and the HLB, which can be easily calculated according to the expression by Griffin: HLB = E/5; where E is the weight percentage of ethylene glycol units in the considered molecule.

[0028] Examples of calculating HLB values are given below:

[0029] SR349 is an ETHOXYLATED (3) BISPHENOL A DIACRYLATE.

[0031] This calculation shows that SR 349 cannot be used as the first diluent monomer in the instant claimed invention because even though it is lipophilic (HLB < 10) it is difunctional and it can't be used as the second diluent monomer in the instant claimed invention because it is not hydrophilic.

SR344 is a POLYETHYLENE GLYCOL (400) DIACRYLATE

o o

C„_I = _C„-C-0-_CH_!-CH_I-O _:CH_!-_C¾-0+-C„_;-C„_!-0-C-C„=C„_!

[0032] This calculation shows that SR 344 cannot be used as the first diluent monomer in the instant claimed invention because it is not lipophilic (HLB < 10) but it can be used as the second diluent monomer in the instant claimed invention because it is hydrophilic and difunctional.

SR504 is ETHOXYLATED (4) NONYL PHENOL ACRYLATE

[0033] This calculation shows that SR 504 can be used as the first diluent monomer in the instant claimed invention because it is lipophilic (HLB < 10) and monofunctional, but it cannot be used as the second diluent monomer in the instant claimed invention because it is not hydrophilic and is monofunctional.

http://www.dsm-agi.com/products overview, hp

** Miramer® M 144 is EO (4) PEA and is available from Miwon Specialty Chemical Co. Ltd.

Abbreviation Common Chemical Names

PEG400DA Polyethylene glycol 400 (molecular weight) diacrylate

PEG600DA Polyethylene glycol 600 (molecular weight) diacrylate

TEGDA Triethyelene glycol diacrylate

BPA4EODA Ethoxylated (4 moles of ethylene oxide) bisphenol A diacrylate

BPA 1 0EODA Ethoxylated ( 10 moles of ethylene oxide) bisphenol A diacrylate

TMP6EOTA Ethoxylated (Six moles of ethylene oxide) trimethylolpropane triacrylate

TMP9EOTA Ethoxylated ( 10 moles of ethylene oxide) trimethylolpropane triacrylate

TMP 1 5EOTA Ethoxylated (1 5 moles of ethylene oxide) trimethylolpropane triacrylate

TMP20EOTA Ethoxylated (20 moles of ethylene oxide) trimethylolpropane triacrylate

EONPA Ethoxylated (4 moles of ethylene oxide) nonyl phenol

EOEOEA 2 (2-ethoxyethoxy) ethyl acrylate

EO(4)PEA Ethoxylated (4 moles of ethylene oxide) phenol For information on the other known ingredients typically used in formulating radiation curable primary coatings, see the reference text, "Specialty Optical Fibers Handbook", edited by Alexis Mendez and T.F. Morse, ©2007 Elsevier, Inc., chapter 4, "Optical Fiber Coatings" written by Steven R. Schmid and Anthony F. Toussaint, pages 95- 122. Specific details on formulations and suitable ingredients, including urethane

(meth)acrylate oligomers and how to synthesize them, diluent monomers, photoinitiators, adhesion promoters and other additives such as antioxidants, stabilizers and slip additives may be found in the following list of issued US patents and published US patent applications, all of which are incorporated by reference, in their entirety: 5496870, 5664041 , 5837750, 6040357, 6052503, 6054217, 6080483, 61 10593, 6136880, 6214899, 6240230, 6298189, 6306924, 63 19549, 6323255, 6339666, 6350790, 6359025, 6362249, 6391459, 6391936, 6438306, 6472450, 6534557, 6579618, 6599956, 6661959, 66801 18, 6797740, 6961 508, 7067564, 7076142, 7171 103, 721443 1 , 7276543, 7493000, 7706659, 7740944, 7865055, 7886612, 7906566, 8218931, 8242202, 20020127400, 2008 0226909, 2008 022691 1 , 2008 0226912, 2008 0226913, 2008 0226914, 2008 0226915, 2008

0226916, 2008 0233397, 2008 0241 535, 2008 0069656, US Patent Application 14/043036 filed Oct. 1 , 201 3, US Published Patent Applications 201 1 0150410, 2012 0003474, and 2012 0196122.

Oligomer synthesis

[0034] The oligomers useful in the various aspects of the present invention will be described in the following sections. Generally, the oligomers are urethane (meth)acrylate oligomers, comprising a (meth)acrylate group, urethane groups and a backbone (the term (meth)acrylate including acrylates as well as methacrylate functionalities).

[0035] The typical method of synthesizing the oligomer is the following.

Mix the polyol with secondary hydroxyl groups, 2-ethoxy alcohol, BHT stabilizer, acrylic acid and the polyol with primary hydroxyl groups and stir for 15 minutes. Then add in the isocyanate. After the isocyanate is added then slowly pour in the hydroxy ethyl acrylate. Heat the mixture to 40°C for two hours, checking the amount of reaction by testing for the amount of residual unreacted NCO groups to determine the midpoint. When the midpoint of the reaction is achieved add in the catalyst and heat to 80 °C. Then run the test for amount of residual unreacted NCO groups at regular intervals until the results indicate the completion of the oligomer synthesis reaction.

[0036] In an embodiment of the invention, a hybrid "outside in" method of oligomer synthesis is used. The proposed benefit of using this hybrid "outside in" method is based on the different reactivity of the secondary hydroxyl of the Acclaim® polypropylene glycol (Acclaim® polyol is a polyether polyol based on propylene oxide available from Bayer), which is about an order of magnitude less reactive than the primary hydroxyls used for the ends of the oligomer.

[0037] It is believed, without intending to be bound thereby, that a desired feature of this method of oligomer synthesis is as follows. First, when no catalyst is added, the polyols are mixed to ensure that the primary hydroxyls of the HEA and the 2-ethyl-hexyl alcohol are in a low, consistent concentration in the polypropylene glycol. The isocyanate, such as IPDI, is added to this and the objective is that the end groups add to one end of the IPDL The differential reactivity of the NCO one each IPDI helps to make sure that this happens. Note that if the primary hydroxyls are not mixed in well that there is a risk of a high concentration area of primary hydroxyl end groups and then there would be more of a chance to form the undesirable HEA-IPDI-HEA or HEA-IPDI-ethyl hexyl molecules. For every one of these undesirable molecules, a tri-block of the PPG4000 will be made rather than the desirable targeted di-block of the PPG4000. The formation of the tri-block of the PPG4000 is undesired, because it makes the viscosity of the oligomer much higher than targeted.

[0038] The advantage of doing this reaction in the diluent PPG4000 is

1 ) the heat of reaction is dissipated more efficiency, meaning there is less or no chance of a runaway acrylate polymerization due to an uncontrolled exothermic reaction

2) therefore the minimum batch size is increased,

3) there is less chance of making the double end capped isocyanate molecules, i.e. , less chance of getting too high of a viscosity oligomer, and

4) the energy of reaction is used to heat up the reactor.

[0039] After the two hours at 40°C, then the catalyst is added making the PPG4000 react to the mono-end capped isocyanate. The advantage of using the bismuth catalyst is good adhesion promoter stability is obtained in the formulated product and it is less toxic and more environmentally friendly than tin.

Diluent Monomers

[0040] In the instant claimed radiation curable primary coating composition, at least two diluent monomers are present;

(i) wherein the first diluent monomer contains a polar segment and a non-polar

segment;

(ii) is monofunctional;

(iii) is more non-polar than polar, meaning that it is lipophilic, such that the HLB value is less than about 10;

(iv) is present in the composition at about 20 wt.% to about 60 wt.%; and

wherein the second diluent monomer

(v) contains a non-polar segment and a polar segment; (vi) is multifunctional ;

(vii) is more polar than non-polar, meaning that it is hydrophilic, such that the HLB value is greater than about 10; and

(viii) is present in the composition at from about 0.5 wt.% to about 20 wt.%.

[0041 ] The first diluent monomer can be selected from the group consisting of ethoxylated nonyl phenol acrylates, which are sold commercially by Sartomer as SR 504 and SR 504 D and by AGI-DSM Chemicals as AgiSyn® 2895. An additional first diluent monomer is Miramer™ M 144 which is EO (4) PEA, available from Miwon Specialty Chemical Co. Ltd

[0042] The second diluent monomer can be selected from the group consisting of polyethylene glycol (200 MW) diacrylate (sold commercially by Sartomer as SR259, polyethylene glycol (400 MW) diacrylate (sold commercially by Sartomer as SR344 and by AGI-DSM Chemicals as AgiSyn® 2834), polyethylene glycol (600 MW) diacrylate (sold commercially by Sartomer as SR610 and by AGI-DSM Chemicals as AgiSyn® 2835), ethoxylatedi₅ trimethylolpropane triacrylate (sold commercially by Sartomer as

SR9035), ethoxylated₂o trimethylolpropane triacrylate (sold commercially by Sartomer as SR415 and AGI-DSM Chemicals as AgiSyn® 2867), and 2-(2-ethoxyethoxy) ethyl acrylate (sold commercially by Sartomer as SR256 and by AGI-DSM Chemicals as AgiSyn® 2880).

[0043] Additional Second Diluent monomers include highly ethoxylated (20 mole EO) trimethylolpropane triacrylate (sold commercially by Sartomer as SR415 and AGI-DSM Chemicals as AgiSyn® 2867 ), ethoxylated (30) bisphenol A diacrylate (sold

commercially by Sartomer as CD9038), polyethylene glycol (200) diacrylate (sold commercially by Sartomer as SR259), polyethylene glycol (400) diacrylate (sold commercially by Sartomer as SR603).

[0044] In an embodiment, the first diluent monomer is ethoxylated nonyl phenol acrylate, available from Sartomer as SR 504 or SR 504D and available as AgiSyn® 2895 available from AGI-DSM Corporation. In another embodiment, the first diluent monomer is SR 504D. [0045] SR 504D is a commercially available diluent monomer that has long been used in Primary Coatings. To date, applicants are unaware of any use of this monomer, in radiation curable primary coatings for optical fiber, in connection with a second diluent monomer wherein the second diluent monomer is multifunctional and is hydrophilic, such that the HLB value is greater than about 10. Hydrophilic diluent monomers include SR 344. SR 344 has previously been used as a diluent monomer in radiation curable secondary coatings for optical fibers, but not used in any primary coating that applicants are aware of.

[0046] It is believed, without intending to be bound thereby, that SR 504 and SR 504D include unreacted alcohol moieties wherein these unreacted alcohol moieties contain from about 0 wt.% to less than 5 wt.% of unhindered free hydroxyl groups.

[0047] As discussed previously in this patent application, it has been unexpectedly been found that there is a synergistic combination effect of having these two distinct types of diluent monomers in the same primary coating. The architecture of the coating with two distinct types of diluent monomers causes phase separation between the polar and non- polar parts of the composition, causing the polar parts to want to associate with each other and the non-polar parts to want to associate with each other, thus lining up polar parts with polar and non-polar with non-polar. This "ordering" increases the alignment of the acrylate moieties and thus leads to curing reactions leaving little or no uncured acrylate moieties. Having little or no uncured acrylate moieties leads to the following desirable results: low modulus without cavitation problem, low modulus while retaining the desired fast cure speed, alignment providing for greater "toughness" of the coating, as measured by strain hardening (see Bulters, US 7067564, US7706659, US7865035 and US7886612), which have all herein incorporated by reference in their entirety) and acceptable

elongation-at-break and tear strength functional properties.

Coating Composition Synthesis

[0048] Photoinitiators: photoinitiators are well known in the art of optical fiber coatings. See the previously incorporated by reference US Patents and US Published Patent Applications for information about all acceptable photoinitiators. The photoinitiator can be selected from the group consisting of solid or liquid bis acyl phosphine oxide and solid or liquid bis acyl phosphine (see D 1479 Stable Liquid BAP Photoinitiator and its use in Radiation Curable Compositions, published as US 20120129969, D 1479 Stable Liquid BAP Photoinitiator and its use in Radiation Curable Compositions, published as US 20130237626 and D1492 Liquid BAPO Photoinitiator and its use in Radiation Curable Compositions, published as US

20120129968 with all of these published patent applications being incorporated by reference in their entireties) and 1 -hydroxy-cyclohexyl-phenyl-ketone. In an embodiment the photoinitiator is a mixture of bis acyl phosphine oxide and

1 -hydroxy-cyclohexyl-phenyl-ketone. The addition of the second photoinitiator,

1 -hydroxy-cyclohexyl-phenyl-ketone, is to eliminate the chance of waviness on the surface of the primary which is expected to be done by increasing the surface cure of the primary coating, before the secondary is applied on wet-on-dry fiber coating system.

[0049] To put together the coating composition from all the ingredients, in an embodiment, the following takes place. The oligomer is blended with the monomers, photoinitiator, heat stabilizer, and all other ingredients, except for the acrylated silane, at 70°C, for an hour. Then the coating mixture is cooled to less than 55°C and more than or equal to 50°C, with this temperature being chosen to maintain the stability of the acrylated silane. After the cooling, then the acrylated silane is added and stirred for an hour. At the end of the hour the coating composition is then filtered to less than one micron.

[0050] In an embodiment, the film modulus of the primary coating is from greater than or equal to about 0.1 MPa to less than or equal to about 1 .5 MPa. In an embodiment the modulus of a cured film of the radiation curable Primary Coating composition is from greater than or equal to 0.5 MPa to less than or equal to about 1.0 MPa. In an embodiment the modulus of a cured film of the radiation curable Primary Coating composition is from greater than or equal to 0.65 MPa to less than or equal to about 1 .0 MPa. In an

embodiment the film modulus of the primary coating a cured film of the radiation curable Primary Coating composition has a modulus of greater than or equal to 0.85 MPa to less than or equal to about 1 .0 MPa. [005 1 ] In an embodiment, the film modulus of the secondary coating is from greater than about 0,80 GPa to less than or equal to about 2.8 GPa. In an embodiment, the film modulus of the secondary coating is about 1.5 GPa.

[0052] In an embodiment, the in-situ modulus of the primary coating is from greater than or equal to about 0.1 MPa to less than or equal to about 1.5 MPa. In an embodiment the in-situ modulus of the primary coating is from greater than or equal to about 0.15 MPa to less than or equal to about 1 .0 MPa. In an embodiment the in-situ modulus of the cured primary coating is from greater than or equal to about 0.3 MPa to less than or equal to about 0.9 MPa. In an embodiment the in-situ modulus of a cured radiation curable Primary Coating composition is from greater than or equal to 0.65 MPa to less than or equal to about 1 .0 MPa. In an embodiment the in-situ modulus of the cured primary coating is from greater than or equal to 0.85 MPa to less than or equal to about 1 .0 MPa.

[0053] In an embodiment, the in-situ modulus of the secondary coating is from greater than about 0.80 GPa to less than or equal to about 2.8 GPa. In an embodiment, the in-situ modulus of the secondary coating is from greater than about 1 .80 GPa to less than or equal to about 2.8 GPa. In an embodiment, the in-situ modulus of the secondary coating is from greater than about 2.00 GPa to less than or equal to about 2.8 GPa. In an embodiment, the in-situ modulus of the secondary coating is from greater than about 2.40 GPa to less than or equal to about 2.8 GPa.

[0054] In an embodiment, the in-situ modulus of the secondary coating is from greater than about 1.20 GPa to less than or equal to about 2.2 GPa. In an embodiment, the in-situ modulus of the secondary coating is from greater than about 1.30 GPa to less than or equal to about 1.60 GPa. In an embodiment, the in-situ modulus of the secondary coating is about 1 .5 GPa. In an embodiment, the in-situ modulus of the secondary coating is about 1 .8 GPa.

[0055] The combination of a low modulus primary (in an embodiment 0.80 MPa, in an embodiment 0.65 MPa) or lower wherein the modulus does not increase over time because of a fast cure speed, (gel time faster than 0.50 sec via RTDMA, after application to the optical fiber and curing and using a high modulus secondary (in an embodiment over 1400 MPa ( 1.4 GPa), in another embodiment over 1800 MPa ( 1 .8 GPa), in another embodiment over 2000MPa (2.0 GPa) and in another embodiment from about 2000 MPa to about 2400 MPa (2.0 GPa to about 2.4 GPa) provides unequaled low attenuation due to micro bending.

[0056] The following examples further illustrate the invention but, of course, should not be construed as in any way limiting its scope.

[0057]

[0058] Examples

[0059] Throughout this patent application, the following abbreviations have the indicated meanings:

A- 1 89 γ-mercaptopropyltrimethoxysilane, available from General Electric

BHT 2,6-d m-butyl-p-cresol, available from Fitz Chem

CAS means Chemical Abstracts Registry Number

DBTDL dibutyl tin dilaurate available from OMG Americas

SR 9087 is an alkoxylated phenol acrylate monomer from Sartomer

SR 504 D ethoxylated nonyl phenol, available from Sartomer

SR 344 polyethylene glycol (400) diacrylate, available from Sartomer

HEA hydroxyethyl acrylate, available from BASF

Irganox 1035 thiodiethylene bis (3,5-di- er/-butyl-4-hydroxyhydrocinnamate),

available from Ciba

P2010 polypropylene glycol (2000 MW), available from BASF

IPD1 isophorone diisocyanate available from Bayer

TDI a mixture of 80 % 2,4-toluene diisocyanate and 20 % 2,6-toluene

diisocyanate, available from Bayer

TDS 100 % 2,4-toluene diisocyanate, a solid

Photomer* 4066 ethoxylated nonolphenol acrylate, available from Cognis

Irgacure^® 819 phenylbis(2,4,6-trimethyl benxoyl) phosphine oxide, available from Ciba

SR 306 tripropylene glycol diacrylate, available from Sartomer

SR 349 ethoxylated (3) bisphenol A diacrylate, available from Sartomer

Miramer® M 144 EO (4) PEA and is available from Miwon Specialty Chemical Co. Ltd. acrylated silane 3-acryloxypropyltrimethoxysilane available from Gelest, Inc. as

SIA0200.0, see

http://www.qelest.com/qelest/forms/GeneralPaqes/Applications/co uplinq agents composites. aspx

[0060] Example 1

Formulation for Radiation Curable Primary Coating of Example 1 :

CHEMICAL TYPE PRIMARY COATING WT.%

Urethane acrylate oligomer # 1 54.84 phenol ethylene (4) glycol acrylate Miramer® M 144 19.00 cthoxylated phenol acrylate AgiSyn© 2895 22.66 photoinitiator Irgacure* 819 1.5 adhesion promoter SIA0200.0 from Geiest, Inc. 0.50 stabilizer Irganox® 1035 FF 0.50 polyethylene glycol (400) diacrylate, SR 344

1 .00 available from Sartomer

total 100.00

[0061] Example 2

Formulation for Radiation Curable Primary Coating of Example 2

PRIMARY COATING WT.%

oligomer #2 48.005

SR-504D 48.245

Irgacure® 8 19 1 .500

SIA0200.0 from Gelest, Inc. 0.500

Irganox® 1035 FF 0.500

SR-344 1 .250

100.000

[0062] Example 3

Formulation for Radiation Curable Primary Coating of Example 3:

PRIMARY COATING WT.%

oligomer #3 48.005

SR-504D 48.245

Irgacure^e819 1.500

SIA0200.0 from Gelest, Inc. 0.500

Irganox® 1035 FF 0.500

SR-344 1.250

Total 100.000

[0063] Example 4

[0064] Formulation for Radiation Curable Primary Coating of Example

Viscosity

[0065] The viscosity is measured using a Physica MC l O Viscometer. The test samples are examined and if an excessive amount of bubbles is present, steps are taken to remove most of the bubbles. Not all bubbles need to be removed at this stage, because the act of sample loading introduces some bubbles.

[0066] The instrument is set up for the conventional Z3 system, which is used. The samples are loaded into a disposable aluminum cup by using the syringe to measure out 1 7 cc. The sample in the cup is examined and if it contains an excessive amount of bubbles, they are removed by a direct means such as centrifugation, or enough time is allowed to elapse to let the bubbles escape from the bulk of the liquid. Bubbles at the top surface of the liquid are acceptable.

[0067] The bob is gently lowered into the liquid in the measuring cup, and the cup and bob are installed in the instrument. The sample temperature is allowed to equilibrate with the temperature of the circulating liquid by waiting five minutes. Then, the rotational speed is set to a desired value which will produce the desired shear rate. The desired value of the shear rate is easily determined by one of ordinary ski ll in the art from an expected viscosity range of the sample. The shear rate is typically 50 s^"1 or 100 s^"1.

[0068] The instrument panel reads out a viscosity value, and if the viscosity value varied only slightly (less than 2 % relative variation) for 1 5 seconds, the measurement is complete. If not, it is possible that the temperature had not yet reached an equilibrium value, or that the material is changing due to shearing. If the latter case, further testing at different shear rates will be needed to define the sample's viscous properties. The results reported are the average viscosity values of three test samples. The results are reported either in centipoises (cps) or milliPascal - seconds (mPa s), which are equivalent.

[0069] The viscosity of the Coatings of Examples 3 and 4 was measured, using the above described test method, at five different temperatures. The results are as follows:

[0070J

[0071 ] These results indicate that these compositions demonstrate the desired temperature thinning properties of a radiation curable coating for optical fiber in that as the temperature increases, mimicking the application temperature of the coating on cooling glass optical fiber, the viscosity of the composition decreases, making it sufficiently thin to appropriately pass through the coating dies and onto the fiber.

[0072] Example 5 Secondary Coating

[0073] Table 1 : Ingredients in Oligomer A

Ingredient by Function in VVt.% in

Chemical Name / Description CAS Number

Trade Name Formula Oligomer A

HEA end capper 2-hydroxy-ethyl acrylate 8 1 8-61 - 1 1 5.66 hexahydro anhydride hexahydro phthalic anhydride 85-42-7 20,77 phthalic

anhydride

YD- 126 di-epoxy bisphenol A diepoxy 1675-54-3 24.68

Dabco LV 33 catalyst triethyline diamine: 280-57-9 0. 10

1 ,4-diazabicyclo[2.2.2]octane solution

TPP catalyst triphenyl phosphine 603-35-0 0.08

BHT stabilizer 3,5-di-?eri-butyl-4-hydroxytoluene 128-37-0 0.06

SR-306 reactive tripropylene glycol diacrylate 42978-66-5 26.65 diluent

SR-833S reactive tricyclodecane dimethanol diacrylate 42594- 17-2 12.00 diluent [007 J Table 2: Ingredients in Oligomer B

Ingredient by Function in Wt.% in

Chemical Name / Description CAS Number

Trade Name Formula Oligomer B

HEA end capper 2-hydroxy-ethyl acrylate 8 18-61 - 1 16.60

BHT stabilizer 3,5-dWeri-butyl-4-liydroxytoluene 128-37-0 0.50

PTHF 650 polyoi poly THF, poly(tetramethylene ether) 2 190-06- 1 44.30 glycol

TDI diisocyanate toluene diisocyanate 2,4-TDI CAS: 24. 10

584-84-9 and

2,6-TDI CAS:

91 -08-7

DBTDL catalyst dibutyi tin dilaurate 77-58-7 0,05

IBOA reactive diluent isobornyl acrylate 5888-33-5 14.45

Table 3 : Ingredient in Oligomer C

Ingredient by Function in Wt.% in

Chemical Name / Description CAS Number

Trade Name Formula Oligomer C

CN120Z epoxy di aery late Bisphenol A epoxy diacrylate 5581 8-57-0 100

[0075] Fable 4: Ingredients in the Secondary Composition of Example 5

[0076] To make this composition, the individual oligomers are first synthesized or

acquired, and then the ingredients are blended together until sufficient mixing takes place to make a homogeneous composition.

Draw Tower Simulator Description and Test Methods

[0077] In the early years of optical fiber coating developments, all newly developed

primary and Secondary Coatings were first tested for their cured film properties and then submitted for evaluation on fiber drawing towers. Out of all the coatings that were requested to be drawn, it was estimated that at most 30 % of them were tested on the draw tower, due to high cost and scheduling difficulties. The time from when the coating was first formulated to the time of being applied to glass fiber was typically about 6 months, which greatly slowed the product development cycle.

[0078] It is known in the art of radiation cured coatings for optical fiber that when either the Primary Coating or the Secondary Coating was applied to glass fiber, its properties often differ from the flat film properties of a cured fi lm of the same coating. This is believed to be because the coating on fiber and the coating flat film have differences in sample size, geometry, UV intensity exposure, acquired UV total exposure, processing speed, temperature of the substrate, curing temperature, and possibly nitrogen inerting conditions.

[0079] Equipment that would provide similar curing conditions as those present at fiber manufacturers, in order to enable a more reliable coating development route and faster turnaround time has been developed. This type of alternative application and curing equipment needed to be easy to use, low maintenance, and offer reproducible performance. The name of the equipment is a "draw tower simulator" hereinafter abbreviated "DTS". Draw tower simulators are custom designed and constructed based on detailed examination of actual glass fiber draw tower components. All the measurements (lamp positions, distance between coating stages, gaps between coating stages and UV lamps, etc.) are duplicated from glass fiber drawing towers. This helps mimic the processing conditions used in fiber drawing industry.

[0080] One known DTS is equipped with five Fusion F600 lamps - two for the upper

coating stage and three for the lower. The second lamp in each stage can be rotated at various angles between 1 5- 135°, allowing for a more detailed study of the curing profile.

[008 1 ] The "core" used for the known DTS is 130.0 ± 1 .0 μιη stainless steel wire. Fiber drawing applicators of different designs, from different suppliers, are available for evaluation. This configuration allows the application of optical fiber coatings at similar conditions that actually exist at industry production sites.

[0082] The draw tower simulator has already been used to expand the analysis of radiation curable coatings on optical fiber. A method of measuring the Primary Coating' s in-situ modulus that can be used to indicate the coating's strength, degree of cure, and the fiber's performance under different environments in 2003 was reported by P. A. M. Steeman, J.J. M. Slot, H. G. H. van Melick, A. A. F. v.d. Ven, H. Cao, and R. Johnson, in the Proceedings of the 52nd IWCS, p. 246 (2003). In 2004, Steeman et al. reported on how the rheological high shear profile of optical fiber coatings can be used to predict the coatings' processability at faster drawing speeds P. A. M. Steeman, W. Zoetelief, H. Cao, and M. Bulters, Proceedings of the 53rd IWCS, p. 532 (2004). The draw tower simulator can be used to investigate further the properties of primary and Secondary Coatings on an optical fiber.

Draw Tower Simulator Examples

[0083] The Primary Coating of Example 2 and the Secondary Coating of Example 5 are used to coat wire in a draw tower simulator.

[0084] The wire is run at five different line speeds, 750 meters/minute, 1200

meters/minute, 1500 meters/minute, 1 800 meters/minute and 21 00 meters/minute.

[0085] Drawing is carried out using wet on dry mode. Wet on dry mode means the liquid Primary Coating is applied wet, and then the liquid Primary Coating is cured to a solid layer on the wire. After the Primary Coating is cured, the Secondary Coating is applied and then cured as well. The cured Primary Coating on the wire is tested for initial %RAU, initial in-situ modulus and initial Tube T_g. The coated wire is then aged for one month at 85°C and 85 % relative humidity. The cured Primary Coating on the wire is then aged for one month at 85 °C and 85 % relative humidity and tested for %RAU, in-situ modulus and aged Tube T_g.

Set-up conditions for the Draw Tower Simulator:

- Zeidl dies are used. S99 for the primary and S I 05 for the secondary.

- 750, 1000, 1200, 1500, 1800, and 2100 m/min are the speeds.

- 5 lamps are used in the wet on dry process

- (2) 600 W/in² D Fusion UV lamps are used at 100 % for the 1 ° coatings.

- (3) 600 W/in² D Fusion UV lamps are used at 100 % for the 2° coatings.

- Temperatures for the two coatings are 55 °C. The dies are set to 40 °C.

- Carbon dioxide level is 5-8 liters/min at each die.

- Nitrogen level is 20 liters/min at each lamp.

- Pressure for the primary coating is 1 bar at 25 m/min and goes up to 3 bar at 1000 m/min.

- Pressure for the secondary coating is 1 bar at 25 m/min and goes up to 4 bar at 1000 m/min. Percent Reacted Acrylate Unsaturation for the Primary Coating (abbreviated as %RA U) Primary Test Method:

[0086] Degree of cure on the inside Primary Coating on an optical fiber or metal wire is determined by FTIR using a diamond ATR accessory. FTIR instrument parameters include: 100 co-added scans, 4 cm^{" 1} resolution, DTGS detector, a spectrum range of 4000-650 cm^{" 1} , and an approximately 25 % reduction in the default mirror velocity to improve signal-to-noise. Two spectra are required; one of the uncured liquid coating that corresponds to the coating on the fiber or wire and one of the inner Primary Coating on the fiber or wire. A thin film of contact cement is smeared on the center area of a 1 -inch square piece of 3-mil Mylar film. After the contact cement becomes tacky, a piece of the optical fiber or wire is placed in it. Place the sample under a low power optical microscope. The coatings on the fiber or wire are sliced through to the glass using a sharp scalpel. The coatings are then cut lengthwise down the top side of the fiber or wire for approximately 1 centimeter, making sure that the cut is clean and that the outer coating does not fold into the Primary Coating. Then the coatings are spread open onto the contact cement such that the Primary Coating next to the glass or wire is exposed as a flat film. The glass fiber or wire is broken away in the area where the Primary Coating is exposed.

[0087] The spectrum of the liquid coating is obtained after completely covering the

diamond surface with the coating. The liquid should be the same batch that is used to coat the fiber or wire if possible, but the minimum requirement is that it must be the same formulation. The final format of the spectrum should be in absorbance. The exposed Primary Coating on the Mylar film is mounted on the center of the diamond with the fiber or wire axis parallel to the direction of the infrared beam. Pressure should be put on the back of the sample to insure good contact with the crystal. The resulting spectrum should not contain any absorbances from the contact cement. If contact cement peaks are observed, a fresh sample should be prepared. It is important to run the spectrum immediately after sample preparation rather than preparing any multiple samples and running spectra when all the sample preparations are complete. The final format of the spectrum should be in absorbance.

[0088] For both the liquid and the cured coating, measure the peak area of both the acrylate double bond peak at 810 cm^{" 1} and a reference peak in the 750-780 cm^{" 1} region. Peak area is determined using the baseline technique where a baseline is chosen to be tangent to absorbance minima on either side of the peak. The area under the peak and above the baseline is then determined. The integration limits for the liquid and the cured sample are not identical but are similar, especially for the reference peak.

[0089] The ratio of the acrylate peak area to the reference peak area is determined for both the liquid and the cured sample. Degree of cure, expressed as percent reacted acrylate unsaturation (%RAU), is calculated from the equation below:

where R_L is the area ratio of the liquid sample and R_F is the area ratio of the cured primary. In-sit Modulus of Primary Coating

[0090] The in-situ modulus of a Primary Coating on a dual-coated (soft Primary Coating and hard Secondary Coating) glass fiber or a metal wire fiber is measured by this test method. The detailed discussion on this test can be found in Steeman, P. A.M., Slot, J.J.M., Melick, N.G.H. van, Ven, A.A.F. van de, Cao, H. & Johnson, R. (2003).

Mechanical analysis of the in-situ Primary Coating modulus test for optical fibers may be determined in accordance with the procedure set forth in Proceedings 52^nd

International Wire and Cable Symposium (IWCS, Philadelphia, USA, November 10- 13, 2003), Paper 41 .

[0091 ] For sample preparation, a short length (~ 2 mm) of coating layer is stripped off using a stripping tool at the location ~ 2 cm from a fiber end. The fiber is cut to form the other end with 8 mm exactly measured from the stripped coating edge to the fiber end. The portion of the 8 mm coated fiber is then inserted into a metal sample fixture, as schematically shown in Figure 6 of the paper [ 1 ] referenced above. The coated fiber is embedded in a micro tube in the fixture; the micro tube consisted of two half cylindrical grooves; its diameter is made to be about the same as the outer diameter (~ 245 μητι) of a standard fiber. The fiber is tightly gripped after the screw is tightened; the gripping force on the Secondary Coating surface is uniform and no significant deformation occurred in the coating layer. The fixture with the fiber is then mounted on a DMA (Dynamic Mechanical Analysis) instrument: Rheometrics Solids Analyzer (RSA-II). The metal fixture is clamped by the bottom grip. The top grip is tightened, pressing on the top portion of the coated fiber to the extent that it crushed the coating layer. The fixture and the fiber must be vertically straight. The non-embedded portion of the fiber should be controlled to a constant length for each sample; 6mm in our tests. Adjust the strain-offset to set the axial pretension to near zero (-1 g ~ 1 g).

[0092] Shear sandwich geometry setting is selected to measure the shear modulus G of the Primary Coating. The sample width, W, of the shear sandwich test is entered to be 0.24 mm calculated according to ation:

wherein R_j and R_p are bare fiber and Primary Coating outer radius respectively. The geometry of a standard fiber, R/ = 62.5 μηι and R_p = 2.5 μιτι, is used for the calculation. The sample length of 8 mm (embedded length) and thickness of 0.03 mm (Primary Coating thickness) are entered in the shear sandwich geometry. The tests are conducted at room temperature (~ 23 °C). The test frequency used is 1.0 radian/second. The shear strain ε is set to be 0.05. A dynamic time sweep is run to obtain 4 data points for measured shear storage modulus G. The reported G is the average of all data points.

[0093] This measured shear modulus G is then corrected according to the correction method described in the paper [ 1 ] referenced above. The correction is to include the glass stretching into consideration in the embedded and the non-embedded parts. In the correction procedures, tensile modulus of the bare fiber (E ) needs to be entered. For glass fibers, Ef = 70 GPa. For the wire fibers where stainless steel S3 14 wires are used,

Ef= 120 GPa. The corrected G value is further adjusted by using the actual Rf and R values. For glass fibers, fiber geometry including i?/and R_p values is measured by PK2400 Fiber Geometry System. For wire fibers, Rf is 65 μιη for the 130 μιη diameter stainless steel S314 wires used; R_p is measured under microscope. Finally, the in-situ modulus E (tensile storage modulus) for Primary Coating on fiber is calculated according to E = 3 G. The reported E is the average of three test samples.

In Situ DMA for T_g Measurements of Primary and Secondary Coatings on an Optical Fiber [0094] The glass transition temperatures (T_g) of Primary and Secondary Coatings on a dual-coated glass fiber or a metal wire fiber are measured by this method. These glass transition temperatures are referred to as "Tube T_g".

[0095] For sample preparation, strip ~ 2 cm length of the coating layers off the fiber as a complete coating tube from one end of the coated fiber by first dipping the coated fiber end along with the stripping tool in liquid N₂ for at least 10 seconds and then strip the coating tube off with a fast motion while the coating layers are still rigid.

[0096] A DMA (Dynamic Mechanical Analysis) instrument: Rheometrics Solids Analyzer (RSA-II) is used. For RSA-II, the gap between the two grips of RSAI1 can be expanded as much as 1 mm. The gap is first adjusted to the minimum level by adjusting strain offset. A simple sample holder made by a metal plate folded and tightened at the open end by a screw is used to tightly hold the coating tube sample from the lower end. Slide the fixture into the center of the lower grip and tighten the grip. Using tweezers to straighten the coating tube to upright position through the upper grip. Close and tighten the upper grip. Close the oven and set the oven temperature to a value higher than the T_g for Secondary Coating or 100 °C with liquid nitrogen as temperature control medium. When the oven temperature reached that temperature, the strain offset is adjusted until the pretension was in the range of 0 g to 0.3 g.

[0097] Under the dynamic temperature step test of DMA, the test frequency is set at

1 .0 radian/second; the strain is 5 ^χ 10^"3 ; the temperature increment is 2 °C and the soak time is 10 seconds. [0098] The geometry type is selected as cylindrical. The geometry setting was the same as the one used for secondary in-situ modulus test. The sample length is the length of the coating tube between the upper edge of the metal fixture and the lower grip, 1 1 mm in our test. The diameter (D) is entered to be 0.16 mm according to the following equation:

where R_S and R_P are secondary and Primary Coating outer radius respectively. The geometry of a standard fiber, R_S = 122.5 μιη and ?^ = 92.5 μιη, is used for the calculation. A dynamic temperature step test is run from the starting temperature (100 °C in our test) till the temperature below the Primary Coating T_g or -80 °C. After the run, the peaks from tan δ curve are reported as Primary Coating T_g (corresponding to the lower temperature) and Secondary Coating T_g (corresponding to the higher temperature). Note that the measured glass transition temperatures, especially for primary glass transition temperature, should be considered as relative values of glass transition temperatures for the coating layers on fiber due to the tan δ shift from the complex structure of the coating tube.

Draw Tower In-situ In-situ modulus, Simulator Tests %RAU % AU modulus, MPa GPa

Primary Secondary Primary Secondary Primary Secondary

Line Speed in Coating Coating Coating Coating Coating Coating Meters/minute

Not

750 m/min Example 2 Example 5 94.23 98.48 measured Not measured

1200 m/min Example 2 P xample 5 91.04 99.85 0.19 2.5

1500 m min Example 2 Example 5 90.65 99.34 0.17 2.7

1800 m/min Example 2 Example 5 85.73 98.17 0.14 2.0

2100 m/min Example 2 Example 5 85.10 96.46 0.16 2,4

At 21 00 meters/min the primary coating has an in-situ T_g of -52 °C and the secondary coating has an in-situ T_g of 71 °C.

[0099] The use of the terms "a" and "an" and "the" and similar referents in the context of describing the invention (especially in the context of the following claims) are to be construed to cover both the singular and the plural, unless otherwise indicated herein or clearly contradicted by context. The terms "comprising," "having," "including," and "containing" are to be construed as open-ended terms (i. e. , meaning "including, but not limited to,") unless otherwise noted. Recitation of ranges of values herein are merely intended to serve as a shorthand method of referring individually to each separate value falling within the range, unless otherwise indicated herein, and each separate value is incorporated into the specification as if it were individually recited herein. All methods described herein can be performed in any suitable order unless otherwise indicated herein or otherwise clearly contradicted by context. The use of any and all examples, or exemplary language (e.g. , "such as") provided herein, is intended merely to better illuminate the invention and does not pose a limitation on the scope of the invention unless otherwise claimed. No language in the specification should be construed as indicating any non- claimed element as essential to the practice of the invention. [00100] Preferred embodiments of this invention are described herein, including the best mode known to the inventors for carrying out the invention. Variations of those preferred embodiments may become apparent to those of ordinary skill in the art upon reading the foregoing description. The inventors expect skilled artisans to employ such variations as appropriate, and the inventors intend for the invention to be practiced otherwise than as specifically described herein. Accordingly, this invention includes all modifications and equivalents of the subject matter recited in the claims appended hereto as permitted by applicable law. Moreover, any combination of the above-described elements in all possible variations thereof is encompassed by the invention unless otherwise indicated herein or otherwise clearly contradicted by context.

Claims

39

Claims

[00101 ] 1. A radiation curable Primary Coating composition comprising

(a) at least one urethane (meth)acrylate functional oligomer;

(b) at least one photoinitiator,

(c) at least two diluent monomers;

wherein the first diluent monomer

(i) contains a polar segment and a non-polar segment;

(ii) is monofunctional;

(iv) is present in the composition at about 20 wt.% to about 60 wt.%; and wherein the second diluent monomer

(v) contains a polar segment and a non-polar segment;

(vi) is multifunctional;

(viii) is present in the composition at from about 0.5 wt.% to about 20 wt.%.

2. The radiation curable Primary Coating composition of claim 1, wherein in the composition the first diluent monomer comprises unreacted alcohol moieties wherein these unreacted alcohol moieties contain from 0 wt.% to less than 5 wt.% of unhindered free hydroxyl groups.

3. The radiation curable Primary Coating composition of claim 1 or 2, wherein there are at least two photoinitiators present with the second photoinitiator selected to improve the surface cure.

4. The radiation curable Primary Coating composition of any one of claims 1-3. wherein a cured film of the radiation curable Primary Coating composition has a modulus of greater than or equal to 0.1 MPa to less than or equal to about 1.5 MPa.

5. The radiation curable Primary Coating composition of any one of claims 1-4, wherein the glass transition temperature of this cured coating composition is from -30°C to -60°C. 6. The radiation curable Primary Coating composition of any one of claims

1 -5, wherein a cured film of the radiation curable Primary Coating composition has a modulus of less than or equal to 0.65 MPa.

7. The radiation curable Primary Coating composition of any one of claims 1-6, wherein the first diluent monomer is ethoxylated phenol acrylate and the second diluent monomer is polyethylene glycol (400) diacrylate.

8. The radiation curable Primary Coating composition of any one of claims 1-7, wherein the photoinitiator is selected from the group consisting of solid or liquid bis acyl phosphine oxide, solid or liquid bis acyl phosphine and 1-hydroxy-cyclohexyl- phenyl-ketone.

9. A process for coating a glass optical fiber with a radiation curable Primary Coating, comprising

(a) operating a glass drawing tower at a line speed of between 600 meters/minute and 2400 meters/minute to produce a glass optical fiber;

(b) applying the radiation curable Primary Coating composition according to any one of claims 1 -8 onto the surface of the optical fiber; and

(c) optionally applying radiation to effect curing of said radiation curable Primary Coating composition according to any one of claims 1 -8, (d) applying a radiation curable Secondary Coating onto the surface of the radiation curable Primary Coating Composition according to any one of claims 1-8;

(e) applying radiation to effect curing of said Secondary Coating and, if step (c) did not take place, also to effect curing of the radiation curable primary coating according to any one of claims 1 -8.

10. The process of claim 9 wherein said optical fiber is a single mode optical fiber. 1 1. The process of claim 9 wherein said optical fiber is a multimode optical fiber.

12. An optical fiber wherein the primary coating on the optical fiber is the cured radiation curable composition according to any one of claims 1-8 and the secondary coating on the optical fiber is the cured radiation curable secondary coating, wherein the radiation curable secondary coating has the following composition, before cure:

49.5 wt.% of Oligomer A, wherein Oligomer A is a polyester acrylate Oligomer;

20.30 wt.% of Oligomer B, wherein Oligomer B is a polyether-urethane acrylate oligomer;

- 14.92 wt.% of Oligomer C, wherein Oligomer C is an epoxy diacrylate oligomer;

10.89 wt.% of a diluent monomer, wherein said diluent monomer is tripropylene oxide diacrylate,

2.75 wt.% of a first photoinitiator, wherein said first photoinitiator is 1 -hydroxy cyclohexyl phenyl ketone;

- 0.76 wt.% of a second photoinitiator, which is

2,4,6-trimethylbenzoyldiphenylphosphine oxide,

0.5 wt.% of a stabilizer, which is thiodiethylene bis

(3,5-di-ieri-butyl-4-hydroxyhydrocinnamate),

0.13 wt.% of a first silicone additive, which is a nonreactive silicone glycol copolymer surfactant and

0.25 wt.% of a second silicone additive, which is a proprietary silicone-ethylene oxide/propylene oxide copolymer; and wherein

the film modulus of the secondary coating is from greater than about 0.80 GPa to less than or equal to about 2.8 GPa.

13. The optical fiber of Claim 8 wherein the cured radiation curable secondary coating on the optical fiber has an in-situ modulus of at least about 1.5 GPa when the secondary coating is applied to fiber being drawn at line speeds of from about 600 m/min to about 2400 m/min.

14. The optical fiber of Claim 8, wherein the optical fiber is a single mode optical fiber.

15. The optical fiber of Claim 8, wherein the optical fiber is a multi-mode optical fiber.