Radiation curable primary coating composition for an optical fiber

The invention relates to a radiation curable primary coating composition for coating an optical fiber, composed of a component having a first end and a second end, a saturated aliphatic backbone, and at least one epoxide group at the first end of the component, and at least one reactive functional group at the second end; a mixture of acrylate monomers, composed of a first monomer having one acrylate group, and a second monomer having at least two acrylate groups; and a photoinitiator. The invention further relates to a radiation curable primary coating composition for coating an optical fiber, composed of a component having a first end and a second end, a saturated aliphatic backbone, and at least one epoxide group at the first end of the component, and at least one reactive functional group at the second end; a mixture of acrylate monomers, composed of a first monomer having one vinyl ether group, and a second monomer having at least two vinyl ether groups; and a photoinitiator. The invention further relates to a radiation curable primary coating composition for coating an optical fiber, a component having a first end and a second end, composed of a saturated aliphatic backbone, and at least one epoxide group at the first end of the component, and at least one first reactive functional group at the second end; a mixture of acrylate monomers, composed of a first monomer having one acrylate group, and a second monomer having at least two functional groups, comprising a second functional group and a third functional group; and a photoinitiator. The invention further relates to an optical fiber coated with the cured primary composition of the present invention.

FIELD OF THE INVENTION 
The present invention relates to a radiation curable primary coating 
composition for an optical fiber and an optical fiber coated with the 
primary coating composition. 
BACKGROUND OF THE INVENTION 
Glass optical fibers require protective coatings to preserve the inherent 
strength of the glass and to buffer the fiber from microbending induced 
attenuation. Two coatings are generally used. The first coating, which is 
applied to the surface of the optical fiber, is generally referred to as 
the primary coating. The primary coating, once cured, is a soft, rubbery 
material that serves as a buffer to protect the fiber by relieving the 
stress created when the fiber is bent, cabled or spooled. The secondary or 
outer coating is applied over the primary coating. The secondary coating 
functions as a hard, protective layer that prevents damage to the glass 
fiber during processing and use. 
Certain characteristics are desirable for the primary coating. The primary 
coating must maintain adequate adhesion to the glass fiber during thermal 
and hydrolytic aging, yet be strippable for splicing purposes. 
The modulus of the primary coating must be low to cushion and protect the 
fiber by relieving stress on the fiber, which can induce microbending and, 
consequently, inefficient signal transmission. This cushioning effect must 
be maintained through a broad temperature range. Thus, it is necessary for 
the primary coating to have a low glass transition temperature (Tg). The 
low glass transition temperature will ensure that the coating remains in a 
rubbery state throughout a broad temperature range. 
Another property the primary coating should possess is resistance to 
moisture. Moisture will rapidly degrade the strength of the primary 
coating and the underlying glass fiber during stress. Moisture will also 
adversely affect the adhesion of the primary coating to the glass, 
resulting in possible delamination. It is desirable for the coating to be 
as water resistant as possible. Moreover, the primary coating should be 
resistant to oils in filling compounds that are used to waterproof the 
fiber in the cable structure. Swelling of the primary coating by these 
oils can lead to signal attenuation. 
It is also economical for manufacturers to apply the primary coating as 
rapidly as possible. Thus, the primary coating composition should undergo 
curing at higher line speeds. 
Finally, the viscosity and shelf life of the primary coating is also 
important. Formulation stability of at least six to twelve months is 
considered good shelf life. Viscosity can typically be somewhat adjusted 
by regulation of the temperature at which the coatings are applied. 
However, it is advantageous to set the viscosity high enough so as to 
maintain proper rheology and handling of the coating, but low enough to 
facilitate bubble release and to minimize the amount of heat needed in the 
preparation. Excessive heat is undesirable because it may result in 
premature gelling or viscosity buildup due to possible thermal initiation 
of polymerization. 
The use of urethane oligomers possessing terminal reactive groups in the 
primary coating for optical fibers is known in the art. U.S. Pat. Nos. 
5,536,529 and 5,538,791 to Shustack; U.S. Pat. No. 5,336,563 to Coady et 
al.; U.S. Pat. No. 5,373,578 to Parker et al.; and International Patent 
Application No. WO 91/03498 to Vandeberg et al. disclose the preparation 
and application of urethane oligomers to glass fibers and other articles. 
The preparation of the prior art urethane oligomer typically involves the 
reaction between an organic isocyanate compound and an alcohol. In some 
cases, the urethane oligomer possesses terminal acrylate and vinyl ether 
groups. None of these references, however, disclose curing the liquid 
polymers or oligomers of the present invention with functional monomers 
such as acrylates or vinyl ethers. 
The use of urethane oligomers possessing terminal reactive groups in the 
secondary coating is disclosed in U.S. Pat. No. 5,015,709 to Birkle et al. 
and U.S. Pat. No. 4,902,727 to Aoki et al. These references, however, do 
not disclose curing a liquid polymer or oligomer of the present invention 
with functional monomers such as acrylates and vinyl ethers. 
The use of epoxidized diene polymers possessing hydroxyl groups for the 
preparation of coating compositions is disclosed in U.S. Pat. No. 
5,264,480 to Bening et al. These polymers react with isocyanates to 
produce coating compositions. There is no disclosure in Bening et al., 
however, of adding other components such as acrylates and vinyl ethers to 
produce the coating composition. 
U.S. Pat. No. 5,536,772 to Dillman et al. discloses the preparation of a 
coating composition for an optical fiber composed of an unsaturated 
epoxidized diene polymer and a tackifying resin. The coating composition 
also contains radiation curable diluents such as acrylates, methacrylates, 
and vinyl ethers. There is no disclosure in Dillman et al. of the types of 
acrylates, methacrylates, and vinyl ethers that are used. Moreover, 
Dillman et al. does not disclose the use of two or more acrylate or vinyl 
ether monomers or an acrylate monomer in combination with another monomer 
to produce a primary coating composition. 
U.S. Pat. No. 5,247,026 to Erickson et al. discloses the preparation of a 
coating composition composed of an epoxidized diene star polymer. Similar 
to the disclosure of Dillman et al., Erickson et al. also discloses that 
the coating composition also contains radiation curable diluents such as 
acrylates, methacrylates, and vinyl ethers. However, Erickson et al. does 
not disclose the use of two or more acrylate or vinyl ether monomers or an 
acrylate monomer in combination with another monomer to produce a primary 
coating composition. 
European Patent Application No. 0 124 057 to Pasternack et al. discloses 
coating an optical fiber with an ultraviolet-initiated, cationically 
curable polyepoxide, a polysiloxane with a plurality of hydroxyl groups, 
and a photoinitiator and/or photosensitizer. There is no disclosure in 
Pasternack et al. to use functionalized monomers such as acrylates or 
vinyl ethers in the coating composition. 
In light of the above, it would be very desirable to have a primary coating 
composition that possesses enhanced or increased thermal and hydrolytic 
stability. Another object of the present invention is to produce a primary 
coating that increases or enhances the static fatigue strength of a glass 
fiber. Finally, it would be advantageous to use starting materials that 
are less expensive than those used in the prior art to produce a primary 
coating composition for a glass fiber. The present invention solves such a 
need in the art while providing surprising advantages. 
SUMMARY OF THE INVENTION 
In accordance with the purpose(s) of this invention, as embodied and 
broadly described herein, this invention, in one aspect, relates to a 
radiation curable primary coating composition for coating an optical 
fiber, comprising: 
(a) a component having a first end and a second end, comprising: 
i) a saturated aliphatic backbone, and 
ii) at least one epoxide group at the first end of component (a), and at 
least one reactive functional group at the second end of component (a); 
(b) a mixture of acrylate monomers, comprising 
iii) a first monomer having one acrylate group, and 
iv) a second monomer having at least two acrylate groups; and 
c) a photoinitiator. 
The invention further relates to a radiation curable primary coating 
composition for coating an optical fiber, comprising: 
(a) a component having a first end and a second end, comprising: 
i) a saturated aliphatic backbone, and 
ii) at least one epoxide group at the first end of component (a), and at 
least one first reactive functional group at the second end of component 
(a); and 
(b) a mixture of monomers, comprising 
iii) a first monomer having one acrylate group or vinyl ether group, and 
iv) a second monomer having at least two functional groups, comprising a 
second functional group and a third functional group, and 
(c) a photoinitiator. 
The invention further relates to a radiation curable primary coating 
composition for coating an optical fiber, comprising: 
(a) a component having a first end and a second end, comprising: 
i) a saturated aliphatic backbone, and 
ii) at least one epoxide group at the first end of component (a), and at 
least one reactive functional group at the second end of component (a); 
and 
(b) a mixture of vinyl ether monomers, comprising 
iii) a first monomer having one vinyl ether group, and 
iv) a second monomer having at least two vinyl ether groups; and 
(c) a photoinitiator. 
The invention further relates to a radiation curable primary coating 
composition for coating an optical fiber, comprising: 
(a) a component having a first end and a second end, comprising: 
i) a saturated aliphatic backbone, and 
ii) at least one epoxide group at the first end of component (a), and at 
least one reactive functional group at the second end of component (a); 
(b) a monoacrylate having from 6 to 20 carbon atoms; and 
(c) a photoinitiator. 
The invention also relates to an article comprising an optical fiber and a 
composition of the present invention wherein the composition has been 
cured as the primary coating composition on the optical fiber. 
The invention further relates to an article comprising an optical fiber and 
a cured composition wherein the cured composition comprises: 
(a) a component having a first end and a second end, comprising: 
i) a saturated aliphatic backbone, and 
ii) at least one epoxide group at the first end of component (a), and at 
least one reactive functional group at the second end of component (a); 
(b) a mixture of acrylate monomers, comprising 
iii) a first monomer having one acrylate group, and 
iv) a second monomer having at least two acrylate groups; and 
c) a photoinitiator, 
wherein the composition has been cured as the primary coating composition 
on the optical fiber. 
The invention further relates to an article comprising an optical fiber and 
a cured composition wherein the cured composition comprises: 
(a) a component having a first end and a second end, comprising: 
i) a saturated aliphatic backbone, and 
ii) at least one epoxide group at the first end of component (a), and at 
least one first reactive functional group at the second end of component 
(a); and 
(b) a mixture of monomers, comprising 
iii) a first monomer having one acrylate group, and 
iv) a second monomer having at least two functional groups, comprising a 
second functional group and a third functional group, and 
(c) a photoinitiator, 
wherein the composition has been cured as the primary coating composition 
on the optical fiber. 
The invention further relates to an article comprising an optical fiber and 
a cured composition wherein the cured composition comprises: 
(a) a component having a first end and a second end, comprising: 
i) a saturated aliphatic backbone, and 
ii) at least one epoxide group at the first end of component (a), and at 
least one reactive functional group at the second end of component (a); 
and 
(b) a mixture of vinyl ether monomers, comprising 
iii) a first monomer having one vinyl ether group, and 
iv) a second monomer having at least two vinyl ether groups; and 
(c) a photoinitiator, 
wherein the composition has been cured as the primary coating composition 
on the optical fiber. 
The invention further relates to an article comprising an optical fiber and 
a cured composition wherein the cured composition comprises: 
(a) a component having a first end and a second end, comprising: 
i) a saturated aliphatic backbone, and 
ii) at least one epoxide group at the first end of component (a), and at 
least one reactive functional group at the second end of component (a); 
(b) a monoacrylate having from 6 to 20 carbon atoms; and 
(c) a photoinitiator, 
wherein the composition has been cured as the primary coating composition 
on the optical fiber. 
Additional advantages of the invention will be set forth in part in the 
description which follows, and in part will be obvious from the 
description, or may be learned by practice of the invention. The 
advantages of the invention will be realized and attained by means of the 
elements and combinations particularly pointed out in the appended claims. 
It is to be understood that both the foregoing general description and the 
following detailed description are exemplary and explanatory only and are 
not restrictive of the invention, as claimed. 
DETAILED DESCRIPTION OF THE INVENTION 
The present invention may be understood more readily by reference to the 
following detailed description of preferred embodiments of the invention 
and the Examples included therein. 
Before the present compositions and articles are disclosed and described, 
it is to be understood that this invention is not limited to specific 
synthetic methods or to particular formulations, as such may, of course, 
vary. It is also to be understood that the terminology used herein is for 
the purpose of describing particular embodiments only and is not intended 
to be limiting. 
In this specification and in the claims which follow, reference will be 
made to a number of terms which shall be defined to have the following 
meanings: 
The singular forms "a," "an" and "the" include plural referents unless the 
context clearly dictates otherwise. 
"Optional" or "optionally" means that the subsequently described event or 
circumstance may or may not occur, and that the description includes 
instances where the event or circumstance occurs and instances where it 
does not. 
In accordance with the purpose(s) of this invention, as embodied and 
broadly described herein, this invention, in one aspect, relates to a 
radiation curable primary coating composition for coating an optical 
fiber, comprising: 
(a) a component having a first end and a second end, comprising: 
i) a saturated aliphatic backbone, and 
ii) at least one epoxide group at the first end of component (a), and at 
least one reactive functional group at the second end of component (a); 
(b) a mixture of acrylate monomers, comprising 
iii) a first monomer having one acrylate group, and 
iv) a second monomer having at least two acrylate groups; and 
(c) a photoinitiator. 
Components (a), (b) iii, and (b) iv are three, distinct components that are 
used to prepare the coating composition of the present invention. 
Component (a) of the present invention is preferably a hetero-telechelic 
polymer that has at least one reactive functional reactive group at one 
end of the polymer and at least one epoxide group at the other end of the 
polymer. In one embodiment, component (a) is a liquid polymer or oligomer. 
Component (a) of the present invention is typically prepared by the 
polymerization of a conjugated diolefin to produce a polydiene. The 
polydiene is then epoxidized and hydrogenated to produce the 
hetero-telechelic polymer. The epoxidation and hydrogenation steps can be 
performed in any order. Methods for preparing component (a) and examples 
of component (a) of the present invention are disclosed in U.S. Pat. No. 
5,247,026 to Erickson et al., U.S. Pat. No. 5,536,772 to Dillman et al., 
and U.S. Pat. No. 5,264,480 to Bening et al., which are all herein 
incorporated by this reference in their entirety. 
In one embodiment, a conjugated diolefin having from 4 to 24 carbon atoms 
can be polymerized anionically to produce component (a). Examples of 
conjugated dienes useful for preparing component (a) of the present 
invention include, but are not limited to, isoprene; 1,4-butadiene; 
1,2-butadiene; 2-methyl-1,3-butadiene; 2-ethyl-1,3-butadiene; 
2-butyl-1,3-butadiene; 2-pentyl-1,3-butadiene; 2-hexyl-1,3-butadiene; 
2-heptyl-1,3-butadiene; 2-octyl-1,3-butadiene; 2-nonyl-1,3-butadiene; 
2-decyl-1,3-butadiene; 2-dodecyl-1,3-butadiene; 
2-tetradecyl-1,3-butadiene; 2-hexadecyl-1,3-butadiene; 
2-isoamyl-1,3-butadiene; 2-phenyl-1,3-butadiene; 2-methyl-1,3-pentadiene; 
2-methyl-1,3-hexadiene; 2-methyl-1,3-heptadiene; 2-methyl-1,3-octadiene; 
and 2-methyl-6-methylene-2,7-octadiene. Other examples of conjugated 
dienes include, but are not limited to, 2-methyl-1,3-nonyldiene; 
2-methyl-1,3-decyldiend; 2-methyl-1,3-dodecyldiene, and the 2-ethyl, 
2-propyl, 2-butyl, 2-pentyl, 2-hexyl, 2-heptyl, 2-octyl, 2-nonyl, 2-decyl, 
2-dodecyl, 2-tetradecyl, 2-hexadecyl, 2-isoamyl, and 2-phenyl compounds. 
Other conjugated dienes include 1,3-butadiene, piperylene, and 
4,5-diethyl-1,3-octadiene. Disubstituted conjugated dienes include, but 
are not limited to, 2,3-dimethyl-1,3-butadiene; 
2,3-dimethyl-1,3-pentadiene; 2,3-dimethyl-1,3-hexadiene; 
2,3-dimethyl-1,3-heptadiene; and 2,3-dimethyl-1,3-octadiene. Difluoro 
conjugated dienes useful for the preparation of component (a) include, but 
are not limited to, 2,3-difluoro-1,3-butadiene; 
2,3-difluoro-1,3-pentadiene; 2,3-difluoro-1,3-hexadiene; 
2,3-difluoro-1,3-heptadiene; and 2,3-difluoro-1,3-octadiene. Alkenyl 
aromatic hydrocarbons such as styrene, alkyl substituted styrene, 
alkoxy-substituted styrenes, vinyl naphthalene, and alkyl-substituted 
vinyl naphthalenes can be copolymerized with the conjugated dienes listed 
above. 
In one embodiment, the aliphatic backbone of component (a) is saturated and 
unsubstituted. In a preferred embodiment, the aliphatic backbone of 
component (a) is poly(ethylene/butylene). 
Depending upon the diene or olefin that is polymerized to generate the 
aliphatic backbone of component (a), a number of different groups can be 
attached to the aliphatic backbone. The term "attached" is defined as a 
group that is not incorporated within the aliphatic backbone. In one 
embodiment, an aliphatic group, a cycloaliphatic group, an aryl group or a 
combination thereof is attached to the saturated aliphatic backbone. In 
another embodiment, a phenyl group is attached to the aliphatic backbone. 
In one embodiment, the aliphatic backbone of component (a) is 
poly(ethylene/butylene/styrene). 
The number of epoxide groups at the first end of component (a) can vary 
depending upon the method used to epoxidize the polymer. Conditions are 
selected in order to epoxidize the highly substituted olefinic double 
bonds. In one embodiment, peracetic acid is suitable for the epoxidation 
of the polydiene. In another embodiment, the number of epoxide groups at 
the first end of component (a) is from 5 to 15, preferably from 9 to 11 
epoxide groups. 
The second end of component (a) has a reactive functional group. The term 
"reactive functional group" for component (a) is any group capable of 
reacting with a compound including, but not limited to, an acrylate; a 
vinyl ether; an epoxide; an alcohol; or an isocyanate. Examples of 
reactive functional groups present at the second end of component (a) of 
the present invention include, but are not limited to, a hydroxyl group, 
an acrylate group, an epoxy group, a vinyl ether group, or a combination 
thereof. In a preferred embodiment, the reactive functional group is a 
hydroxyl group. When the reactive functional group is a hydroxyl group, it 
is possible to convert the hydroxyl group to other reactive functional 
reactive groups using techniques known in the art. 
Component (a) can be prepared in a number of different shapes depending 
upon the polymerization technique used to prepare the polymer. In one 
embodiment, component (a) is linear, star or radial, preferably linear. 
The molecular weight of component (a) can affect the ability of the polymer 
to cure. Low molecular weight polymers require excessive crosslinking in 
order to cure. Crosslinking occurs during the curing of the composition of 
the invention, which enhances the physical properties of the cured 
composition. The term "crosslinking" is defined as the reaction between an 
epoxide group of a first component (a) with an epoxide group or the 
reactive functional group of a second component (a). 
Crosslinking can also occur within the same polymer, such that the reactive 
functional group at the second end of component (a) can react with an 
epoxide group at the first end. The reaction typically involves 
ring-opening of the epoxide by the reactive functional group. The 
crosslinking of component (a) results in the formation of a network or 
lattice. If the molecular weight of the polymer is too high, then it is 
difficult to apply the polymer on the a substrate by melt or other means. 
In one embodiment, the molecular weight of component (a) is from 3,000 to 
15,000, preferably from 5,000 to 7,000, more preferably 6,000. 
In one embodiment, component (a) has from 9 to 11 epoxide groups at the 
first end of component (a), a hydroxyl group at the second end of 
component (a), and the saturated aliphatic backbone is linear. In a 
preferred embodiment, component (a) is KRATON LIQUID.RTM. polymers L-207 
and EKP-206, which are manufactured by Shell Oil Company, Houston, Tex. 
L-207 is a linear polymer with a poly(ethylene/butylene) backbone, a 
hydroxyl group at one terminus of the polymer, and epoxide groups at the 
other terminus. EKP-206 is a linear polymer with a 
poly(ethylene/butylene/styrene) backbone, a hydroxyl group at one terminus 
of the polymer, and epoxide groups at the other terminus. 
In one embodiment, the amount of component (a) is from 40 to 80%, 
preferably from 55 to 75% by weight of the total composition. 
In one embodiment of the invention, Applicant has discovered that by 
combining a mixture of monomers possessing functional groups (component 
(b)) with component (a), it is possible to enhance or increase the 
physical properties of the primary coating. The term "enhance" is defined 
as an increase in a desired effect and/or an increase in the duration of 
the desired effect. The functional monomers used in the present invention 
in component (b) reduce the viscosity of component (a) so that it 
facilitates the application of the coating to the fiber. One advantage of 
the present invention is that by changing the type and amount of the 
functional monomer, it is possible to alter or modify the viscosity of the 
coating composition. 
As described above, component (a) crosslinks with itself to form a network 
or lattice. In one embodiment, the first monomer, the second monomer, and 
the photoinitiator can also crosslink with component (a) if the first 
monomer, second monomer, and photoinitiator are capable of reacting with 
the epoxide or hydroxyl groups of component (a). In a preferred 
embodiment, when the functional monomers (component (b)) are polymerized, 
the resultant polymer is interwoven through the polymer network produced 
by the crosslinking of component (a). This is referred to as an 
interpenetrating network (IPN). In this embodiment, component (b) reacts 
with itself and not component (a). 
The primary coating composition has a number of advantages over prior art 
coatings. First, the coating composition possesses increased thermal and 
hydrolytic stability. Second, the primary coating composition of the 
present invention imparts greater static fatigue strength to the glass 
fiber. Finally, the primary coating composition has a modulus that is in 
the range required to function as a primary coating for an optical fiber. 
Although a monofunctional monomer in the absence of a second monomer can be 
used in this invention, applicant has discovered that the use of a 
monofunctional monomer in the absence of the second monomer results in the 
formation of a coating composition that is inferior to the coating 
compositions of the present invention that are directed to a mixture of a 
monofunctional monomer and a multifunctional monomer. The present 
invention demonstrates the advantages of using a second monomer with two 
or more functional groups to produce a primary coating composition with 
superior physical and mechanical properties. First, the use of the second 
monomer permits the modification of the viscosity of the primary coating. 
Second, the second monomer cures at high speeds when the coating 
composition is exposed to ultraviolet light. Finally, the second monomer 
provides the latitude necessary to adjust the mechanical properties of the 
cured primary coating while maintaining the high thermohydrolytic and 
thermooxidative stability of component (a) in the cured state. 
In one embodiment, the functional monomer comprises a mixture of acrylates 
comprising a first monomer having one acrylate group and a second monomer 
having at least two acrylate groups. In one embodiment, the first monomer 
is an acrylate from C.sub.6 to C.sub.20, preferably from C.sub.8 to 
C.sub.15. The range of carbon atoms is for the organic group of the ester 
(i.e. H.sub.2 C.dbd.CHCO.sub.2 R, where R is from C.sub.6 to C.sub.20). 
The term acrylate also includes methacrylates as well. In one embodiment, 
the first monomer comprises octyl acrylate, decyl acrylate, tridecyl 
acrylate, stearyl acrylate, lauryl acrylate or a combination thereof, 
preferably octyl acrylate, decyl acrylate, or tridecyl acrylate. The terms 
"octyl" and "decyl" include all structural isomers, such as isooctyl, 
isodecyl, n-octyl, and n-decyl. 
Examples of useful first monomers include, but are not limited to, allyl 
methacrylate, tetrahydrofurfuryl methacrylate, isodecyl methacrylate, 
2-(2-ethoxyethoxy)-ethylacrylate, stearyl acrylate, tetrahydrofurfuryl 
acrylate, lauryl methacrylate, stearyl acrylate, lauryl acrylate, 
2-phenoxyethyl acrylate, 2-phenoxyethyl methacrylate, glycidyl 
methacrylate, isodecyl acrylate, isobornyl methacrylate, isooctyl 
acrylate, tridecyl acrylate, tridecyl methacrylate, caprolactone acrylate, 
ethoxylated nonyl phenol acrylate, isobornyl acrylate, polypropylene 
glycol monomethacrylate or a combination thereof. In another embodiment, 
the first monomer comprises ODA-N.RTM., which is a mixture of octyl 
acrylate and decyl acrylate, EBECRYL 110.RTM., which is an ethoxylated 
phenol acrylate monomer, EBECRYL 111.RTM., which is an epoxy monoacrylate, 
or EBECRYL CL 1039.RTM., which is a urethane monoacrylate. These 
monoacrylates are manufactured by UCB Chemicals Corporation, Smyrna, Ga. 
In a preferred embodiment, the first monomer is octyl acrylate, decyl 
acrylate, tridecyl acrylate, isodecyl acrylate, or isobornyl acrylate, or 
a combination thereof. 
In another embodiment, the first monomer is from 10 to 50% by weight, 
preferably from 15 to 30% by weight of the total composition. 
The second monomer is an acrylate of from C.sub.4 to C.sub.20. In one 
embodiment, the second monomer has two acrylate groups. In one embodiment, 
the second monomer comprises 1,6-hexanediol diacrylate; tripropylene 
glycol diacrylate; 1,3-butylene glycol diacrylate; 1,4-butylene glycol 
diacrylate; neopentyl glycol diacrylate; triethylene glycol 
dimethacrylate; ethylene glycol dimethacrylate; tetraethylene glycol 
dimethacrylate; polyethylene glycol dimethacrylate; 1,3-butylene glycol 
diacrylate; 1,4-butanediol diacrylate; 1,4-butanediol dimethacrylate; 
diethylene glycol diacrylate; diethylene glycol dimethacrylate; 
1,6-hexanediol diacrylate; neopentyl glycol dimethacrylate; polyethylene 
glycol (600) dimethacrylate; polyethylene glycol (200) diacrylate; 
tetraethylene glycol diacrylate; triethylene glycol diacrylate; 
polyethylene glycol (400) diacrylate; polyethylene glycol (400) 
dimethacrylate; polyethylene glycol (600) diacrylate; or dipropylene 
glycol diacrylate, or a combination thereof. In a preferred embodiment, 
the second monomer comprises 1,6 hexanediol diacrylate; tripropylene 
glycol diacrylate, or trimethyolpropane diacrylate or a combination 
thereof. 
In another embodiment, the second monomer has three acrylate groups. 
Examples of triacrylates useful in the present invention include, but are 
not limited to, trimethylolpropane triacrylate; pentaerythritol 
triacrylate; trimethylolpropane ethoxy triacrylate, or propoxylated 
glyceryl triacrylate. In a preferred embodiment, the triacrylate is 
trimethylolpropane triacrylate. 
In another embodiment, the second monomer has four or more acrylate groups. 
Examples of these acrylates include, but are not limited to, 
pentaerythritol tetraacrylate; dimethylolpropane tetraacrylate, or 
ethoxylated pentaerythritol tetraacrylate. 
In one embodiment, the first monomer is tridecyl acrylate and the second 
monomer is tripropylene glycol diacrylate. In another embodiment, the 
first monomer is tridecyl acrylate and isobornyl acrylate and the second 
monomer is 1,6-hexanediol diacrylate. In another embodiment, the first 
monomer is tridecyl acrylate and the second monomer is 1,6-hexanediol 
diacrylate. In another embodiment, the first monomer is tridecyl acrylate 
and the second monomer is trimethylolpropane triacrylate. 
In one embodiment, the first monomer is isodecyl acrylate and the second 
monomer is tripropylene glycol diacrylate. In another embodiment, the 
first monomer is isodecyl acrylate and isobornyl acrylate and the second 
monomer is 1,6-hexanediol diacrylate. In another embodiment, the first 
monomer is isodecyl acrylate and the second monomer is 1,6-hexanediol 
diacrylate. In another embodiment, the first monomer is isodecyl acrylate 
and the second monomer is trimethylolpropane triacrylate. 
In one embodiment, the first monomer is octyl acrylate and decyl acrylate 
and the second monomer is tripropylene glycol diacrylate. In another 
embodiment, the first monomer is octyl acrylate, decyl acrylate and 
isobornyl acrylate and the second monomer is 1,6-hexanediol diacrylate. In 
another embodiment, the first monomer is octyl acrylate and decyl acrylate 
and the second monomer is 1,6-hexanediol diacrylate. In another 
embodiment, the first monomer is octyl acrylate and decyl acrylate and the 
second monomer is trimethylolpropane triacrylate. 
In one embodiment, the amount of second monomer is from 2 to 20%, 
preferably from 5 to 15% by weight of the total composition. 
The use of a photoinitiator is required to induce crosslinking of component 
(a) and polymerization of the functional monomers. In one embodiment, the 
photoinitiator comprises a cationic initiator and a free-radical 
initiator. It is known in the art that cationic initiators can induce 
crosslinking of component (a) (see U.S. Pat. No. 5,536,772 to Dillman et 
al.). It also known in the art that free-radical initiators can initiate 
the polymerization of acrylate monomers. 
In one embodiment, the cationic initiator comprises diaryl iodonium 
hexafluoroantimonate, triaryl sulfonium hexafluoroantimonate, triaryl 
sulfonium or hexafluorophosphate or a combination thereof. Triaryl 
sulfonium hexafluoroantimonate and triaryl sulfonium hexafluorophosphate 
are used as 50% by weight in propylene carbonate. In a preferred 
embodiment, the cationic initiator is diaryl iodonium 
hexafluoroantimonate, which is sold under the tradename SARTOMER 
CD1012.RTM., which is manufactured by Sartomer, Exton, Pa. In another 
embodiment, the cationic initiator is from 0.15 to 1.50% by weight, 
preferably from 0.30 to 0.60% by weight of the total composition. In one 
embodiment, the cationic initiator is incorporated within the primary 
coating upon curing. Upon exposure to ultraviolet light, the cationic 
initiator is converted to a cationic species, which increases the acidic 
character of the cured coating. Consequently, the glass fiber coated with 
the cured composition of the present invention will be less susceptible to 
fatigue failure when compared to glass fibers coated with a composition 
that does not contain a cationic initiator. 
In one embodiment, the free-radical initiator comprises 
2,2-dimethoxy-2-phenylacetophenone; 1-hydroxycyclohexyl phenyl ketone; 
2-methyl-1-{4-(methylthio)phenyl}-2-morpholinopropanone-1,2-benzyl-2-N,N-d 
imethylamino-1-(4-morpholinophenyl)-1-butanone; 
2-hydroxy-2-methyl-1-phenyl-propan-1-one, 
4-(2-hydroxyethoxy)phenyl-(2-propyl)ketone; 
2,4,6-{trimethylbenzoyldiphenylphosphine}oxide; or benzophenone; or a 
combination thereof. In another embodiment, the free-radical initiator is 
ESACURE KB1.RTM., ESACURE EB3.RTM., ESACURE TZT.RTM., ESACURE KIP 
100.RTM., or ESACURE KT37.RTM., which are manufactured by Sartomer, Exton, 
Pa. In a preferred embodiment, the free-radical initiator comprises 
2,2-dimethoxy-2-phenylacetophenone, or 1-hydroxycyclohexyl phenyl ketone, 
or a combination thereof. 2,2-Dimethoxy-2-phenylacetophenone is sold under 
the tradename IRGACURE 651.RTM. and 1-hydroxycyclohexyl phenyl ketone is 
sold under the tradename IRGACURE 184.RTM., both manufactured by 
Ciba-Geigy, Hawthorne, N.Y. The selection of the free-radical initiator 
depends upon the wavelength profile of the UV source. In another 
embodiment, the free-radical initiator is from 0.5 to 5.0% by weight, 
preferably from 1.0 to 2.5% by weight of the total composition. 
The invention further relates to a radiation curable primary coating 
composition for coating an optical fiber, comprising: 
(a) a component having a first end and a second end, comprising: 
i) a saturated aliphatic backbone, and 
ii) at least one epoxide group at the first end of component (a), and at 
least one first reactive functional group at the second end of component 
(a); and 
(b) a mixture of monomers, comprising 
iii) a first monomer having one acrylate group or vinyl ether group, and 
iv) a second monomer having at least two functional groups, comprising a 
second functional group and a third functional group, and 
(c) a photoinitiator. 
Applicant has discovered that the first monomer having one acrylate group 
can be combined with a second monomer having at least two functional 
groups. In one embodiment, the first functional group of component (a) and 
the second and third functional groups of the second monomer comprises an 
acrylate group, an epoxy group, a vinyl ether group, a hydroxyl group, or 
a combination thereof. In one embodiment, the first monomer is a vinyl 
ether and the second and third functional group is an acrylate group. In a 
preferred embodiment, the first, second, and third functional group is an 
acrylate group. In this embodiment of the invention, the acrylates 
described above can be used as the first and second monomers. 
In another embodiment, the second monomer is a vinyl ether. Examples of 
vinyl ethers useful in the present invention include, but are not limited 
to, triethylene glycol divinyl ether; cyclohexanedimethanol divinyl ether; 
dodecyl vinyl ether; diethylene glycol divinyl ether; dipropylene glycol 
divinyl ether; hexanediol divinyl ether; butanediol divinyl ether; 
ethylene glycol divinyl ether; tetraethylene glycol divinyl ether; 
trimethylolpropane trivinyl ether; poly-tetrahydrofuran divinyl ether; 
1,3-benzenedicarboxylic acid, bis-{4-ethenyloxy)butyl}ester; pentanedioic 
acid, bis-{{4-{(ethenyloxy)methyl}cyclohexyl}methyl}ester; butanedioic 
acid, bis-{4-(ethenyloxy)butyl}ester; hexanedioic acid, 
bis-{4-(ethenyloxy)butyl}ester; 1,2,4-benzenetricarboxylic acid, or 
tris-{4-(ethenyloxy)butyl}ester or a combination thereof. 
The invention further relates to a radiation curable primary coating 
composition for coating an optical fiber, comprising: 
(a) a component having a first end and a second end, comprising: 
i) a saturated aliphatic backbone, and 
ii) at least one epoxide group at the first end of component (a), and at 
least one reactive functional group at the second end of component (a); 
and 
(b) a mixture of vinyl ether monomers, comprising 
iii) a first monomer having one vinyl ether group, and 
iv) a second monomer having at least two vinyl ether groups; and 
(c) a photoinitiator. 
In one embodiment, the first monomer comprises hydroxybutyl vinyl ether; 
propenylether of propylene carbonate; dodecyl vinyl ether; cyclohexyl 
vinyl ether; 2-ethylhexyl vinyl ether; octadecyl vinyl ether; 1-butanol, 
4-(ethenyloxy)-, benzoate; cyclohexanemethanol, 4-{(ethenyloxy)methyl}-, 
benzoate; ethyl vinyl ether; propyl vinyl ether; isobutyl vinyl ether; 
butyl vinyl ether; ethylene glycol monovinyl ether; ethylene glycol butyl 
vinyl ether; triethylene glycol methyl vinyl ether; cyclohexanedimethanol 
vinyl ether; tert-butyl vinyl ether; tert-amyl vinyl ether; diethylene 
glycol monovinyl ether; hexanediol monovinyl ether; amino propyl vinyl 
ether; or 2-diethylaminoethyl vinyl ether, or a combination thereof. 
In another embodiment, the second monomer comprises triethylene glycol 
divinyl ether; cyclohexanedimethanol divinyl ether; dodecyl vinyl ether; 
diethylene glycol divinyl ether; dipropylene glycol divinyl ether; 
hexanediol divinyl ether; butanediol divinyl ether; ethylene glycol 
divinyl ether; tetraethylene glycol divinyl ether; trimethylolpropane 
trivinyl ether; poly-tetrahydrofuran divinyl ether; 
1,3-benzenedicarboxylic acid, bis-{4-ethenyloxy)butyl}ester; pentanedioic 
acid, bis-{{4-{(ethenyloxy)methyl}cyclohexyl}methyl}ester; butanedioic 
acid, bis-{4-(ethenyloxy)butyl}ester; hexanedioic acid, 
bis-{4-(ethenyloxy)butyl}ester; 1,2,4-benzenetricarboxylic acid, or 
tris-{4-(ethenyloxy)butyl}ester, or a combination thereof. 
In one embodiment, when the first monomer is a vinyl ether, the amount of 
the first monomer is from 10 to 50% by weight of the total composition. In 
one embodiment, when the second monomer possesses at least two vinyl ether 
groups, the amount of the second monomer is from 2 to 20% by weight of the 
total composition. 
In one embodiment, when component (b) is a mixture of vinyl ethers, the 
photoiniator comprises a cationic initiator. A free-radical initiator is 
not required in this particular embodiment of the present invention. 
The addition of other additives or components can be added to the primary 
coating composition of the present invention. In one embodiment, the 
primary coating composition comprises an adhesion promoter, a thermal 
oxidative stabilizer, or a combination thereof. In another embodiment, the 
composition comprises an adhesion promoter and a thermal oxidative 
stabilizer. 
The adhesion promoter provides increased adhesion between the glass fiber 
and the primary coating. In one embodiment, the adhesion promoter 
comprises an organofunctional silane. The term "organofunctional silane" 
is defined as a silyl compound with functional groups that facilitate the 
chemical or physical bonding between the glass surface and the silane, 
which ultimately results in increased or enhanced adhesion between the 
primary coating and the glass fiber. 
In one embodiment, the adhesion promoter comprises octyltriethoxysilane, 
methyltriethoxysilane, methyltrimethoxysilane, 
tris-{3-trimethoxysilyl)propyl}isocyanurate, vinyltriethoxysilane, 
vinyltrimethoxysilane, vinyl-tris-(2-methoxyethoxy)silane, 
vinylmethyldimethoxysilane, gamma-methacryloxypropyltrimethoxysilane, 
beta-(3,4-epoxycyclohexyl)ethyltrimethoxysilane, 
gamma-glycidoxypropyltrimethoxysilane, 
gamma-mercaptopropyltrimethoxysilane, 
bis-(3-{triethoxysilyl}-propyl-tetrasulfane, 
gamma-aminopropyltriethoxysilane, aminoalkylsilicone, 
gamma-aminopropyltrimethoxysilane, 
N-beta-(aminoethyl)-gamma-aminopropyltrimethoxysilane, 
bis-(gamma-trimethoxysilylpropyl)amine, 
N-phenyl-gamma-aminopropyltrimethoxysilane, organomodified 
polydimethylsiloxane, 
N-beta-(aminoethyl)-gamma-aminopropylmethyldimethoxysilane, 
gamma-ureidopropyltrialkoxysilane, gamma-ureidopropyltrimethoxysilane, or 
gamma-isocyanatopropyltriethoxysilane, or a combination thereof. In a 
preferred embodiment, the adhesion promoter is 
gamma-methacryloxypropyltrimethoxysilane, which is sold under the 
tradename SILQUEST A-174.RTM. manufactured by OSi Specialties, Inc., 
Endicott, N.Y., U.S.A. 
In one embodiment, the amount of adhesion promoter is from 0.1 to 2.5% by 
weight, preferably from 0.3 to 1.5% by weight of the total composition. 
The thermal oxidative stabilizer inhibits oxidation and thermal degradation 
of the coating composition. In one embodiment, the thermal oxidative 
stabilizer comprises octadecyl 3,5-di-tert-butyl-4-hydroxyhydrocinnamate, 
3,5-bis-(1,1-dimethylethyl)-4-hydroxybenzenepropanoic acid, 
2,2,-bis{{3-{3,5-bis-(1,1-dimethylethyl)-4-hydroxyphenyl}-1-oxopropoxy}met 
hyl}-1,3-propanediyl ester, or thiodiethylene 
bis-(3,5-tert-butyl-4-hydroxy)hydrocinnamate, or a combination thereof. In 
a preferred embodiment, the thermal oxidative stabilizer is octadecyl 
3,5-di-tert-butyl-4-hydroxyhydrocinnamate, which is sold under the 
tradename IRGANOX1076.RTM., manufactured by Ciba-Geigy, Tarrytown, N.Y. 
In another embodiment, the thermal oxidative stabilizer is from 0.1 to 4.0% 
by weight, preferably from 0.15 to 2.5% by weight of the total 
composition. 
In another embodiment, the primary coating compositions of the present 
invention are substantially free of a tackifying resin. In one embodiment, 
no tackifying resin is present in the composition. Applicant has 
discovered that a tackifying resin is not needed to produce a primary 
coating composition with superior physical properties. The prior art 
teaches that a tackifying resin has to be present in the coating 
composition when using polymers similar to those of component (a) of the 
present invention to coat an optical fiber (see U.S. Pat. No. 5,536,772 to 
Dillman et al.). As shown in the forthcoming examples, when a tackifying 
resin is incorporated in the coating composition of the present invention, 
the resultant composition is inferior to the coating composition of the 
present invention. 
In another embodiment, component (a) is from 40 to 80% by weight of the 
total composition, the acrylate monomers are from 15 to 50% by weight of 
the total composition, the photoinitiator is from 1.25 to 5.5% by weight 
of the total composition, the adhesion promoter is from 0.2 to 2.5% by 
weight of the total composition, and the thermal oxidative stabilizer is 
from 0.1 to 4.0% by weight of the total composition, wherein the sum of 
the amount of component (a), the acrylate mixture, the photoinitiator, the 
adhesion promoter, and the thermal oxidative stabilizer is equal to 100%. 
In another embodiment, component (a) is from 60 to 75% by weight of the 
total composition, the acrylate monomers from 20 to 40% by weight of the 
total composition, the photoinitiator is from 1.9 to 3.1% by weight of the 
total composition, the adhesion promoter is from 0.2 to 2.5% by weight of 
the total composition, and the thermal oxidative stabilizer is from 0.1 to 
4.0% by weight of the total composition, wherein the sum of the amount of 
component (a), the acrylate mixture, the photoinitiator, the adhesion 
promoter, and the thermal oxidative stabilizer is equal to 100%. 
In another embodiment, component (a) is L-207, the first monomer is 
tridecyl acrylate, the second monomer is tripropylene glycol diacrylate, 
the free-radical initiator is 1-hydroxycyclohexyl phenyl ketone, the 
cationic initiator is diaryl iodonium hexafluoroantimonate, the thermal 
oxidative stabilizer is 
octadecyl-3,5-di-tert-butyl-4-hydroxyhydrocinnamate, and the adhesion 
promoter is gamma-methacryloxypropyltrimethoxysilane. 
In another embodiment, component (a) is L-207, the first monomer is 
isodecyl acrylate, the second monomer is tripropylene glycol diacrylate, 
the free-radical initiator is 1-hydroxycyclohexyl phenyl ketone, the 
cationic initiator is diaryl iodonium hexafluoroantimonate, the thermal 
oxidative stabilizer is 
octadecyl-3,5-di-tert-butyl-4-hydroxyhydrocinnamate, and the adhesion 
promoter is gamma-methacryloxypropyltrimethoxysilane. 
In another embodiment, component (a) is L-207, the first monomer is 
tridecyl acrylate, the second monomer is tripropylene glycol diacrylate, 
the free-radical initiator is 2,2-dimethoxy-2-phenylacetophenone, the 
cationic initiator is diaryl iodonium hexafluoroantimonate, the thermal 
oxidative stabilizer is 
octadecyl-3,5-di-tert-butyl-4-hydroxyhydrocinnamate, and the adhesion 
promoter is gamma-methacryloxypropyltrimethoxysilane. 
In another embodiment, component (a) is L-207, the first monomer is 
isodecyl acrylate, the second monomer is tripropylene glycol diacrylate, 
the free-radical initiator is 2,2-dimethoxy-2-phenylacetophenone, the 
cationic initiator is diaryl iodonium hexafluoroantimonate, the thermal 
oxidative stabilizer is 
octadecyl-3,5-di-tert-butyl-4-hydroxyhydrocinnamate, and the adhesion 
promoter is gamma-methacryloxypropyltrimethoxysilane. 
In another embodiment, component (a) is L-207, the first monomer is 
tridecyl acrylate and isobornyl acrylate, the second monomer is 
1,6-hexanediol diacrylate, the free-radical initiator is 
2,2-dimethoxy-2-phenylacetophenone, the cationic initiator is diaryl 
iodonium hexafluoroantimonate, and the adhesion promoter is 
gamma-methacryloxypropyltrimethoxysilane. 
In another embodiment, component (a) is L-207, the first monomer is 
isodecyl acrylate, the second monomer is tripropylene glycol diacrylate, 
the free-radical initiator is 2,2-dimethoxy-2-phenylacetophenone, the 
cationic initiator is diaryl iodonium hexafluoroantimonate, and the 
adhesion promoter is gamma-methacryloxypropyltrimethoxysilane. 
In another embodiment, component (a) is EKP-206, the first monomer is 
tridecyl acrylate, the second monomer is 1,6-hexanediol diacrylate, the 
free-radical initiator is 1-hydroxycyclohexyl phenyl ketone, the cationic 
initiator is diaryl iodonium hexafluoroantimonate, the thermal oxidative 
stabilizer is octadecyl-3,5-di-tert-butyl-4-hydroxyhydrocinnamate, and the 
adhesion promoter is gamma-methacryloxypropyltrimethoxysilane. 
In another embodiment, component (a) is EKP-206, the first monomer is 
tridecyl acrylate, the second monomer is 1,6-hexanediol diacrylate, the 
free-radical initiator is 2,2-dimethoxy-2-phenylacetophenone, the cationic 
initiator is diaryl iodonium hexafluoroantimonate, the thermal oxidative 
stabilizer is octadecyl-3,5-di-tert-butyl-4-hydroxyhydrocinnamate, and the 
adhesion promoter is gamma-methacryloxypropyltrimethoxysilane. 
In another embodiment, component (a) is EKP-206, the first monomer is 
isodecyl acrylate, the second monomer is 1,6-hexanediol diacrylate, the 
free-radical initiator is 1-hydroxycyclohexyl phenyl ketone, the cationic 
initiator is diaryl iodonium hexafluoroantimonate, the thermal oxidative 
stabilizer is octadecyl-3,5-di-tert-butyl-4-hydroxyhydrocinnamate, and the 
adhesion promoter is gamma-methacryloxypropyltrimethoxysilane. 
In another embodiment, component (a) is EKP-206, the first monomer is 
isodecyl acrylate, the second monomer is 1,6-hexanediol diacrylate, the 
free-radical initiator is 2,2-dimethoxy-2-phenylacetophenone, the cationic 
initiator is diaryl iodonium hexafluoroantimonate, the thermal oxidative 
stabilizer is octadecyl-3,5-di-tert-butyl-4-hydroxyhydrocinnamate, and the 
adhesion promoter is gamma-methacryloxypropyltrimethoxysilane. 
In another embodiment, component (a) is L-207, the first monomer is 
isodecyl acrylate, the second monomer is 1,6-hexanediol diacrylate, the 
free-radical initiator is 1-hydroxycyclohexyl phenyl ketone, the cationic 
initiator is diaryl iodonium hexafluoroantimonate, and the thermal 
oxidative stabilizer is 
octadecyl-3,5-di-tert-butyl-4-hydroxyhydrocinnamate. 
In another embodiment, component (a) is L-207, the first monomer is 
isodecyl acrylate, the second monomer is 1,6-hexanediol diacrylate, the 
free-radical initiator is 2,2-dimethoxy-2-phenylacetophenone, the cationic 
initiator is diaryl iodonium hexafluoroantimonate, and the thermal 
oxidative stabilizer is 
octadecyl-3,5-di-tert-butyl-4-hydroxyhydrocinnamate. 
In another embodiment, component (a) is L-207, the first monomer is 
tridecyl acrylate, the second monomer is trimethyolpropane triacrylate, 
the free-radical initiator is 2,2-dimethoxy-2-phenylacetophenone, the 
cationic initiator is diaryl iodonium hexafluoroantimonate, the thermal 
oxidative stabilizer is 
octadecyl-3,5-di-tert-butyl-4-hydroxyhydrocinnamate, and the adhesion 
promoter is gamma-methacryloxypropyltrimethoxysilane. 
In another embodiment, component (a) is L-207, the first monomer is 
tridecyl acrylate, the second monomer is trimethyolpropane triacrylate, 
the free-radical initiator is 1-hydroxycyclohexyl phenyl ketone, the 
cationic initiator is diaryl iodonium hexafluoroantimonate, the thermal 
oxidative stabilizer is 
octadecyl-3,5-di-tert-butyl-4-hydroxyhydrocinnamate, and the adhesion 
promoter is gamma-methacryloxypropyltrimethoxysilane. 
In another embodiment, component (a) is L-207, the first monomer is 
isodecyl acrylate, the second monomer is trimethyolpropane triacrylate, 
the free-radical initiator is 2,2-dimethoxy-2-phenylacetophenone, the 
cationic initiator is diaryl iodonium hexafluoroantimonate, the thermal 
oxidative stabilizer is 
octadecyl-3,5-di-tert-butyl-4-hydroxyhydrocinnamate, and the adhesion 
promoter is gamma-methacryloxypropyltrimethoxysilane. 
In another embodiment, component (a) is L-207, the first monomer is 
isodecyl acrylate, the second monomer is trimethyolpropane triacrylate, 
the free-radical initiator is 1-hydroxycyclohexyl phenyl ketone, the 
cationic initiator is diaryl iodonium hexafluoroantimonate, the thermal 
oxidative stabilizer is 
octadecyl-3,5-di-tert-butyl-4-hydroxyhydrocinnamate, and the adhesion 
promoter is gamma-methacryloxypropyltrimethoxysilane. 
The primary coating compositions of the present invention exhibit superior 
physical properties. In one embodiment, the primary coating composition 
has a viscosity of from 2,000 to 15,000 centipoise, preferably from 4,000 
to 7,000 centipoise. In another embodiment, the primary coating has a 
tensile modulus of from 1.0 to 5.0, preferably from 1.5 to 3.0 MPa. In 
another embodiment, the primary coating has a tensile elongation at break 
greater than 50%, preferably greater than 90%. In another embodiment, the 
primary coating has a glass transition temperature less than -20.degree. 
C., preferably lower than -30.degree. C. In another embodiment, the 
primary coating has an oxidation of induction temperature greater than 
230.degree. C., preferably greater than 240.degree. C. In another 
embodiment, the primary coating has a modulus stability at 85.degree. 
C./85% RH for 29 days of less than 20% change, preferably less than or 
equal to 10% change. In another embodiment, the primary coating has a 
weight loss at 125.degree. C. for 7 days of less than 10%. In another 
embodiment, the primary coating has a water absorption of less than 2.0%, 
preferably less than 1.0%. 
The invention further relates to a radiation curable primary coating 
composition for coating an optical fiber, comprising: 
(a) a component having a first end and a second end, comprising: 
i) a saturated aliphatic backbone, and 
ii) at least one epoxide group at the first end of component (a), and at 
least one reactive functional group at the second end of component (a); 
(b) a monoacrylate having from 6 to 20 carbon atoms; and 
(c) a photoinitiator. 
Although this embodiment may be inferior in performance to the embodiments 
of the invention having a mixture of a monomer having one acrylate or 
vinyl ether group and a monomer having at least two functional groups, it 
is still intended that the monoacrylate embodiment be within the scope of 
the present invention. This embodiment still provides operable and 
advantageous properties. For example, the monoacrylates used in the 
present invention exhibit greater compatibility with the liquid polymer 
when compared to multifunctional acrylates. In a preferred embodiment, the 
monoacrylate is an acrylate from C.sub.8 to C.sub.15. 
The invention further relates to an article comprising an optical fiber and 
a cured composition wherein the cured composition comprises: 
(a) a component having a first end and a second end, comprising: 
i) a saturated aliphatic backbone, and 
ii) at least one epoxide group at the first end of component (a), and at 
least one reactive functional group at the second end of component (a); 
(b) a mixture of acrylate monomers, comprising 
iii) a first monomer having one acrylate group, and 
iv) a second monomer having at least two acrylate groups; and 
(c) a photoinitiator, 
wherein the composition has been cured as the primary coating composition 
on the optical fiber. 
The invention further relates to an article comprising an optical fiber and 
a cured composition wherein the cured composition comprises: 
(a) a component having a first end and a second end, comprising: 
i) a saturated aliphatic backbone, and 
ii) at least one epoxide group at the first end of component (a), and at 
least one first reactive functional group at the second end of component 
(a); and 
(b) a mixture of monomers, comprising 
iii) a first monomer having one acrylate group or vinyl ether group, and 
iv) a second monomer having at least two functional groups, comprising a 
second functional group and a third functional group, and 
(c) a photoinitiator, 
wherein the composition has been cured as the primary coating composition 
on the optical fiber. 
The invention further relates to an article comprising an optical fiber and 
a cured composition wherein the cured composition comprises: 
(a) a component having a first end and a second end, comprising: 
i) a saturated aliphatic backbone, and 
ii) at least one epoxide group at the first end of component (a), and at 
least one reactive functional group at the second end of component (a); 
and 
(b) a mixture of vinyl ether monomers, comprising 
iii) a first monomer having one vinyl ether group, and 
iv) a second monomer having at least two vinyl ether groups; and 
(c) a photoinitiator, 
wherein the composition has been cured as the primary coating composition 
on the optical fiber. 
The invention further relates to an article comprising an optical fiber and 
a cured composition wherein the cured composition comprises: 
(a) a component having a first end and a second end, comprising: 
i) a saturated aliphatic backbone, and 
ii) at least one epoxide group at the first end of component (a), and at 
least one reactive functional group at the second end of component (a); 
(b) a monoacrylate having from 6 to 20 carbon atoms; and 
(c) a photoinitiator, 
wherein the composition has been cured as the primary coating composition 
on the optical fiber. 
The coating composition of the present invention can be applied to an 
optical fiber and cured using techniques known in the art. In one 
embodiment, the coating composition is cured by exposing components 
(a)-(b) and the photoinitiator to radiation, preferably ultraviolet 
radiation. 
In one embodiment, the coating composition of the present invention can be 
applied to the fiber in-line by fiber drawing. The coating is applied to 
the fiber and cured before the fiber comes into contact with the draw 
tower capstan, which pulls the fiber from the glass preform. In another 
embodiment, the primary coating can be applied to the fiber and cured 
followed by the application and curing of the secondary coating. In 
another embodiment, the primary coating of the present invention and the 
secondary coating can be applied to the fiber together by a coextrusion 
process followed by curing. 
Typically, nitrogen blankets are used within the cure area to prevent 
oxygen from inhibiting the curing of the functional monomers of the 
present invention. One can vary the application pressure within the 
coating applicator and the number of cure lamps to optimize applications 
for a given line speed.

EXAMPLES 
The following examples are put forth so as to provide those of ordinary 
skill in the art with a complete disclosure and description of how the 
compositions and articles claimed herein are made and evaluated, and are 
intended to be purely exemplary of the invention and are not intended to 
limit the scope of what the inventors regard as their invention. Efforts 
have been made to ensure accuracy with respect to numbers (e.g., amounts, 
temperature, etc.) but some errors and deviations should be accounted for. 
Unless indicated otherwise, parts are parts by weight, temperature is in 
.degree. C. or is at room temperature and pressure is at or near 
atmospheric. 
General Considerations 
Viscosity was measured on a Brookfield LVT Viscometer with the Brookfield 
Thermosel using Splindle #34. 
Ambient tensile properties were determined on a Thwing-Albert Intellect 500 
Tensile Tester at a strain rate of 50%/min. Test samples were prepared by 
curing approximately 0.004 in. thick samples at 40.degree. C. on glass 
plates with either a Fusion Systems H bulb or D bulb at a cure dose of 
approximately 500 mj/cm.sup.2. The coatings were applied with a Bird 
applicator. An H bulb was used with formulations containing IRGACURE 
184.RTM. and a D bulb was used with formulations containing IRGACURE 
651.RTM.. The modulus reported is the tangent modulus to the intercept. 
The D bulb cure dose requirement when using IRGACURE 651.RTM. is 
approximately 350 mj/cm.sup.2. The H bulb cure dose requirement when using 
IRGACURE 184.RTM. is approximately 350 mj/cm.sup.2. 
Tensile modulus at -40.degree. C. was calculated from data obtained on a 
Mettler TMA 40 run in the dynamic mode, using a dynamic load of +/-0.03 
Newtons on a sample having an approximate thickness of 0.010 in. 
The glass transition temperature was determined on a Rheometrics RSA2 at 1 
rad/second. 
The oxidation induction temperature was determined on a Perkin Elmer DSC4 
Differential Scanning Calorimeter at a programmed heat rate of 10.degree. 
C./min under an oxygen atmosphere. 
Aged Film Properties 
Samples prepared as described below were placed in a Blue M Poweromatic 60 
temperature/humidity oven at 85.degree. C./85% relative humidity for 
various periods then removed from the oven and allowed to equilibrate at 
ambient temperature for at least 24 hours. The tensile properties were 
then determined. 
Weight Loss 
A film having an approximate thickness of 0.004 in. thick was placed in a 
forced air oven at 125.degree. C. and removed at intervals to measure 
weight loss. 
Adhesion to Glass 
Glass plates were cleaned in ethanol/KOH solution, rinsed with water then 
dried. The coatings were then applied and cured as previously described 
below. Samples were allowed to sit at ambient temperature for 2 days 
before testing or placing in water. When the sample was placed in water, 
testing was performed immediately after removing the sample from water 
(within 3 minutes). 
The peel test was performed by placing a support tape on the top of the 
cured film and then scoring a 1.0 in. wide strip down through the tape and 
film composite. A 180 degree peel test was then performed using the 
tensile equipment previously described. 
Water Absorption 
Samples were placed in water for 24 hours then immediately dried and 
weighed after removal from the water. The saturated samples were then 
placed in a desiccator for 48 hours and reweighed. The water absorption is 
reported as the % weight loss between the wet and dry samples. 
Example 1--Preparation of Primary Coating Composition 
The oligomer, monomers, and the thermal oxidative stabilizer were placed in 
a vessel and mixed under low shear for several minutes. This mixture was 
then heated to approximately 60.degree. C. with continued mixing until the 
stabilizer was in solution and the blend was homogeneous. The free radical 
initiator was then added, and mixing was continued at 60.degree. C. until 
the initiator was in solution. The cationic initiator was added and the 
temperature was raised to about 90.degree. C. Mixing was continued until 
the cationic initiator was in solution. The blend was cooled to below 
60.degree. C. and the adhesion promoter was added followed by mixing to 
assure a homogeneous blend. 
Laboratory testing to obtain coating properties were conducted without 
filtering the composition. When the coating was applied to a fiber, the 
coating was filtered through a 0.8 micron rated filter. 
In another method, the stabilizer and initiators were dissolved in the 
functionalized monomers of the present invention at an elevated 
temperature. The solution was prefiltered through a 0.45 micron rated 
filter. The remaining components were then added to the mixing vessel and 
blended at 60.degree. C. until the blend was homogeneous. The adhesion 
promoter was added as described above. Filtration of the resultant coating 
composition was performed. This method provides an improved degree of 
particle removal from the coating composition. 
Example 2 
The coating compositions from Example 1 (A-J) were tested for various 
properties as set forth in Table 2 below. 
Primary coating compositions of the present invention that were tested are 
shown in Table 1. All amounts are expressed as parts by weight. The 
coatings were designed to have viscosities at room temperature of about 
5000 centipoise. To obtain higher or lower viscosities, the component 
ratios can be adjusted without significantly effecting the cured 
properties of the coating composition. 
The use of monofunctional acrylates (C.sub.10 and greater) facilitates the 
solubility of other monoacrylates and multifunctional acrylates that have 
limited solubility in the liquid polymer. For example, when isooctyl 
acrylate is used in place of tridecyl acrylate in Formulation A of Table 
1, the compatibility of the tripropyleneglycol diacrylate is marginal. 
When isodecyl acrylate is used, however, compatibility is acceptable. This 
type of behavior was observed with other monomers such as 
trimethylolpropane diacrylate, which are less soluble in the liquid 
polymer than tripropyleneglycol diacrylate. 
Primary coatings when cured generally have a modulus in the range of from 
1.5 to 3.0 MPA. These values assure that fiber signal attenuation will be 
acceptable at ambient temperature. In addition, the cured coating should 
have a low glass transition temperature in order to maintain acceptable 
transmission properties down as low as -40.degree. C. 
The majority of the coating compositions in Table 1 exhibit excellent low 
temperature behavior. Table 2 reveals that by varying the difunctional 
monomer concentration or monomer rigidity, the tensile properties of the 
coating composition can be affected. For example, increasing the amount 
tripropylene glycol diacrylate increases the modulus, particularly at low 
temperature, which was observed for formulation C when compared to 
formulations A and B (Table 2). Using isobornyl acrylate (formulation E) 
also increases the modulus because of its rigid ring structure. 
The weight loss data in Table 2 demonstrates how increasing the crosslink 
density decreases the weight loss at 125.degree. C. 
Of particular note in Table 2 is the exceptional stability of the cured 
coating when exposed to high temperature, high humidity conditions 
(85.degree. C./85% relative humidity) for extended time. The water 
absorption data also reflect the excellent hydrophobic character of these 
coatings. For example, the coating compositions disclosed in U.S. Pat. 
Nos. 5,536,529 and 5,538,791 to Shustack exhibit water absorption no 
better than 1.4%. This value is significantly higher when compared to 
formulations A, C, and E-H in Table 2. 
In Table 2, the modulus of formation for formulation A was measured at 10 
months. The modulus was essentially the same at 10 months when compared to 
the modulus formation of the coating when it was initially prepared. This 
data indicates that the coating compositions of the present invention 
exhibit high stability and good shelf-life over extended periods of time. 
TABLE 1 
__________________________________________________________________________ 
FORMULATION.sup.a 
A B C D E F G H J J 
__________________________________________________________________________ 
COMPONENTS 
SHELL L-207 65 65 65 65 65 65 -- 65 65 65 
SHELL EKP 206 
-- -- -- -- -- -- 65 -- -- -- 
TRIDECYLACRYLATE 
25 25 20 22.5 
17.5 
25 25 30 25 
TRIPROPYLENE GLYCOL 
10 10 15 12.5 
-- -- 10 -- -- 10 
DIACRYLATE 
1,6-HEXANEDIOL 
-- -- -- -- 7.5 
10 -- 10 -- -- 
DIACRYLATE 
ISODECYLACRYLATE 
-- -- -- -- -- -- -- 25 -- -- 
ISOBORNYL ACRYLATE 
-- -- -- -- 10 -- -- -- -- -- 
TRIMETHYLOLPROPANE 
-- -- -- -- -- -- -- -- 5 -- 
TRIACRYLATE 
Octadecyl 3,5-di-tert-butyl- 
2 2 2 2 2 2 2 2 1 1 
4-hydroxyhydrocinnamate 
(IRGANOX 1076) 
1-Hydroxycyclohexyl phenyl 
2 2 2 -- -- 2 2 2 -- -- 
ketone 
(IRGACURE 184) 
2,2-dimethoxy-2- 
-- -- -- 2 2 -- -- -- 2 2 
phenylacetophenone 
(IRGACURE 651) 
Diaryl Iodonium 
0.5 
0.5 
0.5 
0.5 
0.5 
0.5 
0.5 
0.5 
-- 0.5 
Hexafluoroantimonate 
(SARTOMER CD-1012) 
gamma-Methacryloxypropyl 
0.5 
1.0 
0.5 
0.5 
0.5 
-- 0.5 
-- -- 0.5 
trimethoxysilane 
(SILQUEST A-174) 
__________________________________________________________________________ 
.sup.a All formulations are in parts by weight. 
TABLE 2 
__________________________________________________________________________ 
FORMULATION: 
A B C D E F G H I J 
__________________________________________________________________________ 
PROPERTIES 
VISCOSITY, cps 
5350 
5350 
6500 
5600 
4850 
4510 
8550 7100 
5250 
@ 25.degree. C. 
TENSILE @ 25.degree. C. 
Modulus, MPA 
2.2 2.3 2.7 2.3 3.0 2.1 1.9 2.7 1.9 2.8 
Break Str., MPa 
3.3 2.6 3.6 2.9 3.3 2.9 2.0 2.9 2.4 2.5 
(maximum reading) 
Elongation, % 
150 131 129 140 130 135 111 116 161 94 
(maximum reading) 
TENSILE @ -40.degree. C., 
5.3 9.0 6.9 11.0 140 at 
6.3 
Modulus, MPa -40.degree. C. 
(Mettler DTMA @ 1/12 33 at 
hertz) 20.degree. C. 
Tg .degree. C. (tan .delta. @ 1 
-40 
rad/second) 
Oxidation Induction 
243 243 248 244 240 
Temperature, .degree. C. 
Aged Film Properties 
85.degree. C./85% RH AGING 
Modulus, MPa 
0 days 2.3 2.7 
14 days 2.4 3.0 
29 days 2.3 2.7 
Elongation, % 
0 days 131 129 
14 days 95 116 
29 days 144 138 
Weight Loss @ 125.degree. C. 
1 day 8.4 9.5 6.8 6.4 6.9 6.6 
7 days 9.0 9.9 7.4 6.9 7.6 7.3 
22 days 9.6 10.5 
8.0 
Adhesion to Glass, g/in 
(10 in/min, 180.degree. peel) 
dry 45 55 75 
wet (11 days in water) 
25 30 30 
Water Absorption (%) 
0.4 0.5 1.2 0.8 0.4 1.4 
__________________________________________________________________________ 
Example 3 
Fiber Coating and Testing 
Formulations B and E from Example 1 were applied to an optical fiber using 
commercial fiber coating equipment. A urethane acrylate formulation was 
used as the secondary coating. The control fiber was coated with an 
acrylate coating used in the prior art that does not contain component (a) 
of the present invention. The fiber coated with formulations B and E 
displayed superior static fatigue properties relative to the control 
(Table 3). The data in Table 3 demonstrates the significance of using 
component (a) of the present invention with respect to enhancing or 
increasing the static fatigue of an optical fiber. 
TABLE 3 
______________________________________ 
Optical Fiber Static Fatigue in Two Point Bending (at 85.degree. C./85% 
RH) 
Formulation Load (ksi) 
Time to Failure (hours) 
______________________________________ 
B 442 24 
407 375 
E 442 70 
407 &gt;1440.sup.a 
control 442 0.75 
407 2.8 
______________________________________ 
.sup.a The test was terminated after 1440 hours. 
Example 4 
Formulation B was evaluated with respect to transmission properties in a 
temperature cycling test at from -60.degree. C. to 70.degree. C. The test 
was done with fibers in basket weave and loose wind configurations. 
Formulation B was superior in loss (lower signal attenuation) than the 
control at -40.degree. C. and -60.degree. C., and was equivalent to the 
control at and above room temperature. Controls were fibers coated with 
commercial acrylate coatings. The control fiber was drawn from the same 
preform as the test fiber. 
Example 5 
When formulation B was cured by ultraviolet radiation, the resultant film 
had a modulus of about 2.3 MPA at 25.degree. C. In order for the primary 
coating to be useful in fiber optics, the modulus should not be lower than 
1.7 MPA. When the tackifying resin REGALREZ 1085.RTM. (20 parts per 100 
parts L-207) was added to formulation B, the modulus of the film decreased 
to about 1.2 MPA. Moreover, the viscosity of the formulation increased to 
about 10,000 cps at 25.degree. C. Finally, the tackifying resin can 
migrate out of the coating because the resin does not crosslink with the 
functionalized monomers or component (a) of the present invention upon 
curing. 
This data demonstrates that it is undesirable and unnecessary to use a 
tackifying resin in a coating composition for an optical fiber. The 
absence of a tackifying resin in one embodiment of the coating composition 
of the present invention is yet another advantage of the invention. 
Example 6 
Formulations K-M were prepared in order to demonstrate the significance of 
using a multifunctional monomer in combination with a mono functional 
monomer. Formulations K-M were prepared with a monofunctional monomer in 
the absence of a multifunctional monomer (Table 4). Formulations K-M were 
cured at 500 mj/cm.sup.2 using a Fusion Systems D bulb. The weight loss of 
formulations K-M after 1 day at 125.degree. C. was greater than 11%. This 
value is higher than those observed for formulations A-E and I in Table 2. 
This data reveals the added benefit of using a monofunctional monomer in 
combination with a multifunctional monomer when preparing a primary 
coating for an optical fiber in one embodiment of the invention. 
TABLE 4 
______________________________________ 
Formulation.sup.a 
K L M 
______________________________________ 
Component 
Shell L-207 65 65 65 
tridecyl acrylate 
35 -- 17.5 
isobornyl acrylate 
-- 35 17.5 
IRGANOX 1076 .RTM. 
1.0 1.0 1.0 
IRGACURE 651 .RTM. 
2.0 2.0 2.0 
SARTOMER CD 1012 .RTM. 
0.5 0.5 0.5 
______________________________________ 
.sup.a All values expressed in parts. 
Example 7 
Compatibility tests of formulations A and G were conducted in Mobil SHF 402 
oil. This oil is used in synthetic filling compounds that are used to 
waterproof optical fiber cable. In this test, a strip of cured coating (A 
and G) 50 mm in length was placed in the oil at 80.degree. C. for 24 
hours. The increase in length was then determined. In order to be useful 
as a primary coating, the coating should not increase in length by more 
than about 8%. Formulation A increased in length by 6% and formulation G 
by 1%. This data indicates that the presence of the phenyl groups in 
component (a) in formulation G enhances the compatibility of the coating 
composition. With formulation G, an increase in the glass transition 
temperature was observed (slightly above -20.degree. C.); however, the 
increase was expected due to the presence of the phenyl groups. 
Throughout this application, various publications are referenced. The 
disclosures of these publications in their entireties are hereby 
incorporated by reference into this application in order to more fully 
describe the state of the art to which this invention pertains. 
It will be apparent to those skilled in the art that various modifications 
and variations can be made in the present invention without departing from 
the scope or spirit of the invention. Other embodiments of the invention 
will be apparent to those skilled in the art from consideration of the 
specification and practice of the invention disclosed herein. It is 
intended that the specification and examples be considered as exemplary 
only, with a true scope and spirit of the invention being indicated by the 
following claims.