Optical fiber cable assembly

The present invention provides an optical fiber cable assembly including an optical fiber and a reinforcement strand including a plurality of sized glass fibers positioned about the optical fiber, the strand having thereon a dried residue of a secondary aqueous coating composition which is essentially free of a urethane-containing material and includes a first polymer prepared by vinyl addition polymerization of a first monomer component including a first vinyl aromatic monomer and an acrylic monomer and a second polymer different from the first polymer, the second polymer being prepared by vinyl addition polymerization of a second monomer component including a curable polymer of a second vinyl aromatic monomer, wherein the surface of the strand wicks water at a rate of less than about 25.4 millimeters (one inch) in about six hours at a temperature of about 25.degree. C. A method of reducing the wicking of water along the surface of a glass fiber strand is also provided.

FIELD OF THE INVENTION 
This invention is directed to an optical fiber cable assembly including a 
reinforcing strand of glass fibers having a secondary aqueous coating 
and/or impregnating composition applied thereto which inhibits water 
wicking along the strand surface, as well as methods of reducing water 
wicking in an optical fiber cable assembly. 
BACKGROUND OF THE INVENTION 
Typically, the surfaces of glass fiber substrates are coated with a sizing 
composition during the forming process to protect the glass fibers from 
interfilament abrasion. Such sizing compositions can include as components 
film-formers, lubricants, coupling agents, emulsifiers, antioxidants, 
ultraviolet light stabilizers, colorants, antistatic agents and water, to 
name a few. 
U.S. Pat. No. 3,853,605 discloses a combined aqueous sizing and coating 
composition for coating glass fibers shortly after attenuation that 
includes a resorcinol-formaldehyde resin solution, a 
styrene-butadiene-vinylpyridine terpolymer latex, an amino functional 
silane coupling agent, ammonia and an ammonia soluble carboxyl-containing 
polymer, such as an acrylic interpolymer which can include vinyl aromatic 
hydrocarbons such as styrene. Similarly, U.S. Pat. No. 4,060,658 discloses 
an impregnant for glass fibers comprising a resorcinol-formaldehyde resin, 
a terpolymer latex of butadiene-styrene and vinylpyridine, a butadiene 
latex, a portion of which can be replaced by a styrene-butadiene copolymer 
latex, and a wax. U.S. Pat. Nos. 4,164,485 and 4,239,800 disclose an 
impregnant comprising neoprene latex, styrene-butadiene-vinylpyridine 
terpolymer latex, resorcinol formaldehyde resin, resorcinol, formaldehyde, 
wax and natural rubber. The aforementioned coated strands are disclosed 
for use as reinforcement for elastomeric products such as natural or 
synthetic rubber. The use of resorcinol-formaldehyde latex coatings, 
however, gives rise to a number of environmental and health concerns which 
limits their use. 
U.S. Pat. No. 4,663,231 discloses an impregnant for glass fibers for woven 
fabric comprising an elastomeric, ethylene-containing interpolymer, a 
crosslinkable material, and a diene-containing elastomer. 
U.S. Pat. No. 5,182,784 discloses an aqueous coating composition for glass 
fibers consisting essentially of a thermoplastic polyurethane latex, an 
acrylic latex, and either a second acrylic latex or paraffin wax. This 
coating reduces water wicking by glass fibers in applications such as 
optical fiber cable reinforcement. 
In optical fiber cable reinforcement applications, water entering the cable 
assembly can corrode and/or crush the optical fibers by expansion due to 
freezing temperatures. It is desirable to provide an optical fiber cable 
assembly in which the reinforcing glass fibers are coated with a simple, 
economical secondary coating which can withstand the rigorous environment 
to which such reinforcement is subjected, as well as provide water wicking 
resistance characteristics to the reinforcement. 
SUMMARY OF THE INVENTION 
The present invention provides an optical fiber cable assembly comprising 
an optical fiber and a reinforcement strand positioned about at least a 
portion of a periphery of the optical fiber for reinforcing the optical 
fiber cable, the reinforcement strand comprising a plurality of sized 
glass fibers having on a surface thereof a dried residue of a secondary 
aqueous coating composition, the secondary aqueous coating composition 
comprising: (a) a first polymer prepared by vinyl addition polymerization 
of a first monomer component comprising a first vinyl aromatic monomer and 
an acrylic monomer; and (b) a second polymer different from the first 
polymer, the second polymer being prepared by vinyl addition 
polymerization of a second monomer component comprising a curable polymer 
of a second vinyl aromatic monomer, the secondary aqueous coating 
composition being essentially free of a urethane-containing material, 
wherein the surface of the strand having thereon the dried residue of the 
secondary aqueous coating composition wicks water at a rate of less than 
about 25.4 millimeters (one inch) in about six hours at a temperature of 
about 25.degree. C. 
In another aspect of the present invention, the aqueous coating composition 
consists essentially of the first polymer and the second polymer described 
above, wherein the surface of the strand having thereon the dried residue 
of the secondary aqueous coating composition wicks water at a rate of less 
than about 25.4 millimeters (one inch) in about six hours at a temperature 
of about 25.degree. C. 
The present invention also includes a method of reducing the wicking of 
water along the surface of a glass fiber strand comprising a plurality of 
glass fibers, comprising: (a) applying an aqueous sizing composition to 
surfaces of the plurality of glass fibers; (b) at least partially drying 
the sized plurality of glass fibers of (a); (c) gathering the plurality of 
glass fibers to form a strand; (d) applying to the strand a secondary 
coating composition comprising: (1) a first polymer prepared by vinyl 
addition polymerization of a first monomer component comprising a first 
vinyl aromatic monomer and an acrylic monomer; and (2) a second polymer 
different from the first polymer, the second polymer being prepared by 
vinyl addition polymerization of a second monomer component comprising a 
curable polymer of a second vinyl aromatic monomer, the secondary aqueous 
coating composition being essentially free of a urethane-containing 
material; and (e) at least partially drying the secondarily coated strand 
of sized glass fibers of (d), such that the surface of the strand having 
thereon the dried residue of the secondary aqueous coating composition 
wicks water at a rate of less than about 25.4 millimeters (one inch) in 
about six hours at a temperature of about 25.degree. C.

DETAILED DESCRIPTION OF THE INVENTION 
The present invention includes an optical fiber cable assembly 10, such as 
is shown in FIG. 1, comprising: (a) one or more optical fibers 12; and (b) 
a reinforcement strand 14 positioned about at least a portion of a 
periphery 13 of the optical fiber 12 for reinforcing the optical fiber 
cable assembly 10. 
Useful optical fibers are formed from extremely pure silica glass. Suitable 
optical fibers are well known to those of ordinary skill in the art and 
are commercially available from AT&T or Corning Glass Works of Corning, 
N.Y. Such fibers typically have diameters of about 125 microns and lengths 
of about 2 kilometers to about 20 kilometers. 
In typical optical fiber cables 10, the optical fibers 12 are positioned 
about a generally stiff member 16, which can be an epoxy/glass pultruded 
rod or steel rod, for example. The member 16 provides stability to the 
cable to inhibit contraction and expansion of the assembly 10 due to 
environmental temperature change. 
The reinforcement strand 14, which inhibits tension and compressive forces 
on the optical fibers 12, comprises a plurality of sized glass fibers 18 
having on a surface 20 thereof a dried residue of a secondary aqueous 
coating composition 22. As used herein, the terms "size", "sized" or 
"sizing" refer to the aqueous composition applied to the fibers 
immediately after formation of the glass fibers, prior to application of 
the secondary aqueous coating composition. The term "secondary coating" 
refers to a coating composition applied secondarily to one or a plurality 
of strand(s) after the sizing composition is applied, and preferably at 
least partially dried. 
Such sizing compositions can include as components film-formers such as 
thermoplastic or thermosetting polymeric film-formers in a variety of 
forms including emulsions, dispersions, latexes thereof and mixtures 
thereof, such as liquid polyoxyalkylene polyols or polyalkylene polyols 
(polypropylene/polyethylene copolymers); lubricants such as animal, 
vegetable or mineral oils or waxes or cationic lubricants such alkyl 
imidazoline derivatives and polyethyleneimine polyamides; coupling agents, 
including silane coupling agents such as 
gamma-aminopropyltrimethoxysilane, gamma-methacryloxypropyltrimethoxysilan 
e and gamma-glycidoxypropyltrimethoxysilane; emulsifiers; anti-oxidants; 
antifoaming agents; colorants; antistatic agents; bactericides and water, 
to name a few, though preferably starch is not included. 
Examples of suitable sizing compositions are set forth in K. Loewenstein, 
The Manufacturing Technology of Continuous Glass Fibers at pages 243-295 
(2d Ed. 1983) and U.S. Pat. Nos. 4,390,647 and 4,795,678, each of which is 
hereby incorporated by reference. 
It has been observed that the presence of a silicone emulsion in the sizing 
composition, such as LE-9300 silicone emulsion which is commercially 
available from OSi Specialties, Inc. of Danbury, Conn., facilitates 
wicking of water along the sized and secondarily coated strand. Therefore, 
it is preferred that the sizing composition be essentially free of such a 
silicone emulsion. The phrase "essentially free of a silicone emulsion" as 
used herein means that the sizing composition includes less than about 10 
weight percent of such a silicone emulsion, and preferably less than about 
1 weight percent on an aqueous basis. 
The secondary aqueous coating composition includes a first polymer prepared 
by vinyl addition polymerization of a first monomer component comprising a 
first vinyl aromatic monomer(s) and an acrylic monomer(s). 
The first polymer can be water soluble, emulsifiable or dispersible. As 
used herein, the term "water soluble" means that the polymer is capable of 
being essentially uniformly blended and/or molecularly or ionically 
dispersed in water to form a true solution. See Hawley's Condensed 
Chemical Dictionary, (12th Ed. 1993) at page 1075, which is hereby 
incorporated by reference. 
The term "emulsifiable" as used herein means that the polymer is capable of 
forming an essentially stable mixture or being suspended in water in the 
presence of an emulsifying agent. See Hawley's at page 461, which is 
hereby incorporated by reference. Non-limiting examples of suitable 
emulsifying agents are set forth below. 
The term "dispersible" means that the polymer is capable of being 
distributed throughout water as finely divided particles, such as a latex. 
See Hawley's at page 435, which is hereby incorporated by reference. The 
uniformity of the dispersion can be increased by the addition of wetting, 
dispersing or emulsifying agents (surfactants), which are discussed below. 
As used herein, the term "curable" means (1) the first polymer and/or 
second polymer are capable of being at least partially dried by air and/or 
heat; and/or (2) the first polymer and/or second polymer, other components 
of the composition and/or glass fibers are capable of being crosslinked to 
each other to change the physical properties of the first polymer and/or 
second polymer. See Hawley's at page 331, which is hereby incorporated by 
reference. 
Non-limiting examples of suitable first vinyl aromatic monomers include 
vinylbenzene, divinylbenzene, vinyl toluene, alpha methyl styrene, 
halostyrenes such as chlorostyrene, and mixtures thereof. 
The first acrylic monomer(s) (hereinafter "acrylic(s)") can include acrylic 
acid, methacrylic acid, derivatives and mixtures thereof. See Kirk-Othmer 
Encyclopedia of Chemical Technology, Vol. 1 (1963) at page 285, which is 
hereby incorporated by reference. Other non-limiting examples of suitable 
acrylics include esters of acrylic acid and methacrylic acid, such as 
acrylates and methacrylates, including epoxy functional (meth)acrylates, 
acrylic anhydrides, acrylamides, acrylonitriles and derivatives and 
mixtures thereof. Useful acrylics can have hydroxy and/or epoxy 
functionality. 
Useful esters of acrylic or methacrylic acid include straight chain or 
branched alkyl or hydroxyalkyl esters of acrylic or methacrylic acid. 
Useful alkyl esters can contain about 1 to about 24 carbon atoms, and 
preferably containing about 1 to about 18 carbon atoms. Non-limiting 
examples of alkyl esters include methyl (meth)acrylate, ethyl 
(meth)acrylates, propyl (meth)acrylates, butyl (meth)acrylates, pentyl 
(meth)acrylates, hexyl (meth)acrylates, heptyl (meth)acrylates, octyl 
(meth)acrylates, nonyl (meth)acrylates, decyl (meth)acrylates, dodecyl 
(meth)acrylates, tetradecyl (meth)acrylates, hexadecyl (meth)acrylates, 
ethylhexyl (meth)acrylates, lauryl (meth)acrylates, stearyl 
(meth)acrylates and 2-ethylhexyl (meth)acrylate. Suitable hydroxyalkyl 
esters include 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl 
(meth)acrylate, 3-hydroxypropyl (meth)acrylate and hydroxybutyl 
(meth)acrylate. 
Non-limiting examples of other useful acrylics include glycol acrylates 
such as ethylene glycol diacrylate, propylene glycol diacrylate, 
1,3-propanediol acrylate, 1,4-butanediol acrylate, 1,4-butanediol 
methacrylate, 1,6-hexanediol diacrylate, neopentyl glycol diacrylate, 
1,3-butyleneglycol diacrylate and tetraethylene glycol diacrylate. A 
useful polyol acrylate is trimethylolpropane triacrylate. 
Useful epoxy functional acrylates include polyglycidyl acrylates and 
polyglycidyl methacrylates. 
Non-limiting examples of suitable acrylamides include methacrylamide, 
methylolacrylamide, and N-substituted derivatives thereof. 
Non-limiting examples of suitable acrylonitriles include acrylonitrile and 
methacrylonitrile. 
Useful acrylic latexes can be characterized by the temperature at which the 
torsional modulus of an air dried film is 300 kg/cm.sup.2, referred to as 
T300, which is a relative measure of stiffness. A T300 of about 
+22.degree. C. is considered soft while higher numbers indicate more stiff 
and/or tacky acrylics. The acrylics which can be used in the practice of 
this invention preferably have a T300 of about -50.degree. C. to about 
+40.degree. C., preferably about -35.degree. C. to about .+-.35.degree. C. 
The first vinyl aromatic monomer and/or first acrylic monomer can also be 
addition polymerized with other addition polymerizable monomers or 
polymers, as discussed below. 
Non-limiting examples of addition polymerizable monomers which can be 
reacted with the first vinyl aromatic monomer and/or first acrylic monomer 
include other vinyl monomers such as dienes including butadienes such as 
1,3-butadiene and 2,3-dimethyl-1,3-butadiene; isoprene; and chloroprene; 
vinyl halides such as vinyl chloride and vinylidene chloride, vinyl 
acetates, block and graft copolymers thereof. Other useful addition 
polymerizable monomers include amides, such as n-methylol 
(meth)acrylamide; nitriles; pyrrolidones and olefins such as ethylene. 
Mixtures of any of the above addition polymerizable monomers are also 
useful. Preformed polymers of these monomers can also be addition 
polymerized with the first vinyl aromatic monomer and/or first acrylic 
monomer provided the preformed polymer has addition polymerizable 
unsaturation. 
Methods for polymerizing acrylics with themselves and/or other addition 
polymerizable monomers and preformed polymers are well known to those 
skilled in the art of polymers and further discussion thereof is not 
believed to be necessary in view of the present disclosure. For example, 
polymerization of the acrylic can be carried out in bulk, in aqueous or 
organic solvent solution such as benzene or n-hexane, in emulsion, or in 
aqueous dispersion. Kirk-Othmer, Vol. 1 at page 305. The polymerization 
can be effected by means of a suitable initiator system, including free 
radical initiators such as benzoyl peroxide or azobisisobutyronitrile, 
anionic initiation, and organometallic initiation. Molecular weight can be 
controlled by choice of solvent or polymerization medium, concentration of 
initiator or monomer, temperature, and the use of chain transfer agents. 
If additional information is needed, such polymerization methods are 
disclosed in Kirk-Othmer, Vol. 1 at pages 203-205, 259-297 and 305-307, 
which are hereby incorporated by reference. 
The number average molecular weight (Mn) of the first polymer, determined 
by gel permeation chromatography (GPC), can be about 5000 to about 200,000 
and is preferably about 10,000 to about 100,000. The glass transition 
temperature of the first polymer can be about -40.degree. C. to about 
100.degree. C., preferably about -30.degree. C. to about 80.degree. C., 
and more preferably about -25 to about +35 as measured using a 
Differential Scanning Calorimeter (DSC), for example a Perkin Elmer Series 
7 Differential Scanning Calorimeter, using a temperature range of about 
-55.degree. C. to about 150.degree. C. and a scanning rate of about 
20.degree. C. per minute. 
Preferably, the first polymer is present in an emulsion including an 
emulsifying agent, suitable examples of which are discussed below. The 
first polymer is preferably self-crosslinking, although external 
crosslinking agents can be included in the secondary aqueous coating 
composition for crosslinking the first polymer with itself, the second 
polymer or other components of the secondary aqueous coating composition, 
as discussed below. The first polymer can be cationic, anionic or 
nonionic, but preferably is anionic or nonionic. 
Non-limiting examples of commercially available polymers which are believed 
to be addition polymerization products of a vinyl aromatic monomer and an 
acrylic monomer include the following FULATEX.RTM. materials which are 
commercially available from H. B. Fuller Co. of St. Paul, Minn., including 
FULATEX.RTM. PN-3716K, which has a glass transition temperature of about 
26.degree. C., about 44 to about 46 weight percent solids, a pH of about 
2.0 to about 3.5, a viscosity of about 10 to about 200 centipoise 
(measured using Brookfield Viscometer Model RVF at 20 revolutions per 
minute (rpm) at 25.degree. C.). See PN-3716-K Technical Data Sheet of H.B. 
Fuller Co. (Jul. 25, 1994), which is hereby incorporated by reference. 
Other useful FULATEX.RTM. materials include FULATEX.RTM. PN-3716G 
styrene-acrylic copolymer, which is believed to include about 42 weight 
percent butyl acrylate and about 58 weight percent styrene, and 
FULATEX.RTM. PN-3716L1 styrene-acrylic copolymer which is believed to 
include about 45 weight percent butyl acrylate, 53 weight percent styrene 
and less than about 1 weight percent butyl methyl acrylate. FULATEX.RTM. 
PN-3716L1 has a glass transition temperature of about +15.degree. C., 
about 44 to about 46 weight percent solids, a pH of about 7.0 to about 
8.5, a viscosity of about 50 to about 800 centipoise (measured using 
Brookfield Viscometer Model RVF at 20 revolutions per minute (rpm) at 
25.degree. C.). See PN-3716-L1 Technical Data Sheet of H.B. Fuller Co. 
(Jul. 25, 1994). 
Self-crosslinking styrene-acrylic copolymer emulsions believed to be useful 
in the present invention include RHOPLEX.RTM. GL-618, which is an anionic 
emulsion having a glass transition temperature of about +36.degree. C., 
about 47 percent solids, a density of about 8.9 lb./gallon and a pH of 
about 8.6. See "Building Better Nonwovens", a Technical Bulletin of Rohm 
and Haas Specialty Industrial Polymers, (1994), which is hereby 
incorporated by reference. Other useful crosslinkable acrylic-based 
copolymer emulsions include RHOPLEX.RTM. NW-1845 (an anionic emulsion 
having a glass transition temperature of about -21.degree. C., about 44 
percent solids, a density of about 8.8 lb./gallon and a pH of about 6.7) 
and RHOPLEX.RTM. NW-1715 (an anionic emulsion having a glass transition 
temperature of about -6.degree. C., about 44 percent solids, a density of 
about 8.4 lb./gallon and a pH of about 6.2). 
Other examples of useful first polymers include 
acrylontrile-butadiene-styrene terpolymers (ABS) and styrene-acrylonitrile 
copolymers (SAN). 
The amount of first polymer is generally about 5 to about 99 weight percent 
of the secondary aqueous coating composition on a total solids basis, 
preferably about 50 to about 95 weight percent, and more preferably about 
70 to about 90 weight percent. 
The second polymer can be prepared by vinyl addition polymerization of a 
second monomer component comprising a polymer of a second vinyl aromatic 
monomer, however the second polymer must be different from the first 
polymer. For example, the second polymer can be polymerized from a 
different vinyl aromatic monomer or a different addition polymerizable 
monomer. 
The second polymer can be a homopolymer, copolymer or multipolymer and can 
be an addition polymerization product of a monomer component comprising a 
vinyl aromatic monomer, polymer and/or derivatives thereof (hereinafter 
"vinyl aromatic(s)"). The vinyl aromatic of the second polymer can be 
addition polymerized with another addition polymerizable monomer or 
polymer, as discussed below. 
Non-limiting examples of suitable vinyl aromatic monomers include 
vinylbenzene, divinylbenzene, vinyl toluene, alpha methyl styrene, 
halostyrenes such as chlorostyrene, and mixtures thereof. 
Non-limiting examples of addition polymerizable monomers or polymers 
include ethylenically unsaturated monomers including vinyl monomers and 
polymers such as are discussed above, and also include acrylics such as 
are discussed above. 
Methods for polymerizing vinyl aromatic monomers with themselves and/or 
other addition polymerizable monomers and preformed polymers are well 
known to those skilled in the art of polymers and further discussion 
thereof is not believed to be necessary in view of the present disclosure. 
For example, such polymerization methods are disclosed in the Encyclopedia 
of Polymer Science and Technology, Vol. 13 (1970) at pages 130-134; 
156-197 and Kirk-Othmer, Vol. 19 at pages 90-95, all of which are hereby 
incorporated by reference. 
Preferably, the second polymer is present in an emulsion including an 
emulsifying agent, suitable examples of which are discussed below. The 
second polymer is preferably self-crosslinking, although external 
crosslinking agents can be included in the secondary aqueous coating 
composition for crosslinking the second polymer with itself, the first 
polymer or other components of the secondary aqueous coating composition, 
as discussed below. The second polymer can be cationic, anionic or 
nonionic, but preferably is anionic. 
Non-limiting examples of commercially available polymers which can be used 
as the second polymer include the ROVENE.RTM. family of self-crosslinking 
and crosslinkable styrene-butadiene emulsions which are commercially 
available from Rohm and Haas Company of Philadelphia, Pa. For example, 
ROVENE.RTM. 5550 is a useful self-crosslinking anionic carboxylated 
styrene butadiene emulsion having about 45 weight percent styrene and 55 
percent butadiene, 50 percent solids, a pH of about 8.7, a Brookfield 
viscosity of about 300 centipoise, a glass transition temperature of about 
-21.degree. C. (measured by Differential Scanning Calorimeter) and a 
density of about 8.4 lb./gallon at 25.degree. C. "ROVENE.RTM. 5550", a 
Technical Bulletin of Rohm and Haas Company Specialty Polymers (February 
1994) and "Building Better Nonwovens", page 7, a Technical Bulletin of 
Rohm and Haas Company Specialty Polymers (1994), each of which are hereby 
incorporated by reference. Another self-crosslinking styrene butadiene 
emulsion believed to be useful in the present invention is ROVENE.RTM. 
4170, which is also anionic, has about 65 percent styrene and 35 percent 
butadiene, 50 percent solids, a pH of about 9, a glass transition 
temperature of about +3.degree. C. and a density of about 8.3 lb./gallon 
at 25.degree. C. "Building Better Nonwovens" at page 7. 
Non-limiting examples of crosslinkable styrene butadiene emulsions believed 
to be useful in the present invention include ROVENE.RTM. 4402 and 
ROVENE.RTM. 4106. ROVENE.RTM. 4402 is anionic, has about 50 percent 
styrene and 50 percent butadiene, 53 percent solids, a pH of about 8.7, a 
glass transition temperature of about -16.degree. C. and a density of 
about 8.4 lb./gallon at is 25.degree. C. "Building Better Nonwovens" at 
page 7. ROVENE.RTM. 4106 is anionic, has about 90 percent styrene and 10 
percent butadiene, 50 percent solids, a pH of about 8.7, a glass 
transition temperature of about +79.degree. C. and a density of about 8.4 
lb./gallon at 25.degree. C. "Building Better Nonwovens" at page 7. 
Thermoplastic elastomeric materials useful as second polymers in the 
present invention also include styrene-acrylontrile (SAN) copolymers such 
as LUSTRAN, which is commercially available from Monsanto of St. Louis, 
Mo., styrene-butadiene-styrene (SBS) copolymers and 
acrylonitrile-butadiene-styrene (ABS) copolymers, such as CYCOLAC or 
BLENDEX, which are commercially available from GE Plastics of Pittsfield, 
Mass. It should be understood, however, that although these materials can 
be used in the present invention, they can reduce flexibility of the 
secondary coating. Therefore, the selection of such materials depends upon 
the desired properties of the secondary coating for the intended 
application. 
Preferably, the secondary aqueous coating composition includes RHOPLEX.RTM. 
NW-1715 as the first polymer and ROVENE.RTM. 5550, FULATEX.RTM. PN-3716-L1 
or FULATEX.RTM. PN-3716-G as the second polymer. 
The amount of second polymer is typically greater than 0.5 and preferably 
about 1 to about 20 weight percent of the secondary aqueous coating 
composition on a total solids basis, and more preferably about 5 to about 
15 weight percent. 
The secondary aqueous coating composition is essentially free of a 
urethane-containing polymer, which can increase the cost of the coated 
strand. The phrase "essentially free of a urethane-containing polymer" as 
used herein means that the secondary aqueous coating composition contains 
less than two weight percent of a urethane-containing polymer on a total 
solids basis, preferably less than about one weight percent, and most 
preferably the secondary coating composition is free of a 
urethane-containing polymer. 
The phrase "urethane-containing polymer" as used herein means any polymer 
containing one or more units of the structure (I): 
##STR1## 
See Kirk-Othmer, Vol. 21 at pages 56-69, which are hereby incorporated by 
reference. As noted in Kirk-Othmer, Vol. 21 at page 57, the terms urethane 
and polyurethane are commonly used to refer to urethan and polyurethan, 
respectively. As used herein, the terms "urethane" and "polyurethane" are 
used to refer to "urethan" and "polyurethan", respectively. Such 
urethane-containing materials can be elastomeric, thermoplastic or 
thermosetting, and either water soluble, or emulsifiable or dispersible 
with the use of an emulsifying or dispersing agent. 
Urethane-containing polymers are typically condensation products of a 
polyisocyanate material and a hydroxyl-containing material such as 
polyether polyol or polyester polyol and include, for example, 
WITCOBOND.RTM. W-290H thermoplastic polyurethane which is commercially 
available from Witco Chemical Corp. of Chicago, Ill. Other examples of 
commercially available polyurethanes include other members of the 
WITCOBOND.RTM. family of polyurethanes such as WITCOBOND.RTM. W-212 and 
W-234. The WITCOBOND.RTM. W-212 material has a milky-white appearance with 
a 30 percent solids level and a density of 8.7 lb./gallon. The flash point 
is greater than 100.degree. C., the particle charge is cationic and the 
particle size is about 1 micron. The pH at 25.degree. C. (77.degree. F.) 
is 4.5, the viscosity at 25.degree. C. in Brookfield LVF is 50 centipoise, 
and the surface tension is dynes/cm is 41. WITCOBOND.RTM. W-234 aliphatic 
polyurethane is hazy in appearance, has 30 percent solids and a density of 
8.8 lb./gal. The flash point is similar to the W-212 material and the 
particle charge is anionic. The pH at 25.degree. C. is 8.0, the viscosity 
at 25.degree. C. as measured by Brookfield LVF is 100 centipoise, and the 
surface tension in dynes/cm is 54. 
Other examples of thermosetting polyurethanes include BAYBOND XW-110, which 
is commercially available from Bayer and other thermosetting polyurethanes 
which are commercially available from Bayer and E.l. duPont de Nemours Co. 
of Wilmington, Del. Other polyurethanes include thermoplastic urethane 
elastomers, such as RUCOTHANE.RTM. 2011L polyurethane latex, which have a 
solids content of 55 to 65 weight percent and are commercially available 
from Ruco Polymer Corp. of Hicksville, N.Y. Their pH is generally around 
10 with average particle sizes ranging from about 0.8 to about 2.5 
microns. 
Further examples of polyurethane include those that are internally 
emulsified, examples of which may be found in U.S. Pat. Nos. 4,143,091; 
4,208,494 and 4,208,495, each of which is hereby incorporated by 
reference. Other types of polyurethane polymers are those having ionic 
groups present on the polymer molecule such as those disclosed in U.S. 
Pat. No. 4,066,591. 
Other examples of polyurethane polymers include polyurethane ionomers 
having ionic groups such as anionomers and cationomers. Examples of such 
ionomers include anionomers that are produced by reacting organic 
diisocyanates having molecular weights of from about 160 to about 300 with 
alkylene polyols such as ethylene glycol, and optionally other aliphatic 
glycols having molecular weights of from about 62 to about 200 in the 
presence of glycols containing carboxyl, carboxylate, sulfonic acid and/or 
sulfonate groups and having a number average molecular weight of less than 
around 500. These polyurethane polymers containing the ionic groups of 
hydrophilic polyether segments are self-emulsifiable. Other polyurethanes 
include cationic polyurethanes that are formed by quaternizing 
polyaddition reactions. Such polyurethanes are not only self-dispersing 
but typically have average particle sizes of less than about 5 microns. 
The secondary aqueous coating composition can include a crosslinking agent 
for crosslinking the first polymer and the second polymer. Non-limiting 
examples of suitable crosslinkers which can be used when the first polymer 
or second polymer is thermosetting are aminoplast and phenoplast resins 
which are well known to those skilled in the polymer art. For example, the 
CYMEL.RTM. family of melamine resins from American Cyanamid Company are 
useful crosslinking agents. 
Other useful crosslinking agents include blocked isocyanates such as 
BAYBOND XW 116 or XP 7055, epoxy crosslinkers such as WITCOBOND XW by 
Witco Corp., and polyesters such as BAYBOND XP-7044 or 7056. The BAYBOND 
products are commercially available from Bayer of Pittsburgh, Pa. 
Generally, the amount of crosslinker can be about 1 to about 10 weight 
percent of the secondary aqueous coating composition on a total solids 
basis, preferably about 4 to about 6 weight percent, and more preferably 
about 5 to about 6 weight percent. 
The aqueous secondary coating composition can include a fiber lubricant. 
Useful lubricants include cationic, non-ionic or anionic lubricants and 
mixtures thereof. Generally, the amount of lubricant can be about 1 to 
about 15 weight percent of the secondary aqueous coating composition on a 
total solids basis, preferably about 3 to about 12 weight percent, and 
more preferably about 5 to about 10 weight percent. 
Non-limiting examples of such lubricants are glass fiber lubricants which 
include amine salts of fatty acids (which can, for example, include a 
fatty acid moiety having 12 to 22 carbon atoms and/or tertiary amines 
having alkyl groups of 1 to 22 atoms attached to the nitrogen atom ), 
alkyl imidazoline derivatives (such as can be formed by the reaction of 
fatty acids with polyalkylene polyamines), acid solubilized fatty acid 
amides (for example, saturated or unsaturated fatty acid amides having 
acid groups of 4 to 24 carbon atoms such as stearic amide), acid 
solubilized polyunsaturated fatty acid amides, condensates of a fatty acid 
and polyethylene imine and amide substituted polyethylene imines, such as 
EMERY.RTM. 6717, a partially amidated polyethylene imine commercially 
available from Henkel Corporation of Kankakee, Ill. 
A useful alkyl imidazoline derivative is CATION X, which is commercially 
available from Rhone Poulenc of Princeton, N.J. Other useful lubricants 
include RD-1135B epoxidized polyester which is commercially available from 
Borden Chemical of Louisville, Ky., CIRRASOL 185A fatty acid amide, 
KETJENLUBE 522 partially carboxylated polyester which is commercially 
available from Akzo Chemicals, Inc. Of Chicago, Ill. and Protolube HD high 
density polyethylene emulsion which is commercially available from Sybron 
Chemicals of Birmingham, N.J. 
The secondary aqueous coating composition can include emulsifying agents 
for emulsifying the first polymer and/or second polymer. Non-limiting 
examples of suitable emulsifying agents or surfactants include 
polyoxyalkylene block copolymers, ethoxylated alkyl phenols, 
polyoxyethylene octylphenyl glycol ethers, ethylene oxide derivatives of 
sorbitol esters and polyoxyethylated vegetable oils. 
An example of a suitable polyoxypropylene-polyoxyethylene copolymer is the 
material PLURONIC.TM. F-108, which is commercially available from BASF 
Corporation of Parsippany, N.J. This material is a condensate of ethylene 
oxide with hydrophobic bases formed by condensation of propylene oxide 
with propylene glycol. 
Examples of useful ethoxylated alkyl phenols include ethoxylated 
octylphenoxyethanol, phenoxy polyethylene-oxy(ethanol), 
phenoxy(ethyleneoxy)ethanol and nonyl phenoxy poly(ethyleneoxy)ethanol. An 
example of a commercially available ethoxylated octylphenoxyethanol is 
IGE CA-630 from GAF Corporation of Wayne, N.J. 
An example of a polyoxyethylated vegetable oil is EMULPHOR EL-719, which is 
commercially available from GAF Corp. A useful polyoxyethylene octylphenyl 
glycol ether is TRITON X-100, which is commercially available from Rohm & 
Haas of Philadelphia, Pa. TWEEN 21 and 81 are examples of useful ethylene 
oxide derivatives of sorbitol esters. 
Generally, the amount of emulsifying agent can be about 0.5 to about weight 
percent of the secondary aqueous coating composition on a total solids 
basis, and is preferably about 0.5 to about 5 weight percent. 
The secondary aqueous coating composition can include one or more aqueous 
soluble, emulsifiable or dispersible wax materials. The wax material can 
be selected from vegetable, animal, mineral, synthetic or petroleum waxes, 
for example. Preferably, the wax has a high degree of crystallinity and is 
obtained from a paraffinic source, such as a microcrystalline wax. The 
microcrystalline wax can be oxidized. Suitable commercially available 
waxes are, for example, MICHEM.RTM. LUBE 296 microcrystalline wax, 
POLYMEKON.RTM. SPP-W microcrystalline wax and PETROLITE 37 and PETROLITE 
75 microcrystalline waxes. These waxes, which are paraffinic hydrocarbon 
dispersions, are available from Michelman Inc. of Cincinnati, Ohio and the 
Petrolite Corporation of Tulsa, Okla., respectively. Generally, the amount 
of wax can be about 1 to about 10 weight percent of the secondary aqueous 
coating composition on a total solids basis, and preferably about 3 to 
about 5 weight percent. On an aqueous basis, the amount of wax material 
generally can be about 0.25 to about 5 weight percent and, more 
preferably, about 0.5 to about 4.3 weight percent. 
Flame retardant, such as antimony trioxides and halogenated phosphates, and 
antistatic agent can also be included in the secondary aqueous coating 
composition. The amount of flame retardant or antistatic agent can be 
about 1 to about 3 weight percent of the secondary aqueous coating 
composition on a total solids basis. 
A dye can be included in the secondary aqueous coating composition to 
provide a colored strand product. Non-limiting examples of useful 
colorants or pigments include carbon black, nigrosine, and cadmium-based 
compounds, iron oxide-based compounds and chromium compounds. Other useful 
colorants or pigments include AQUA BLACK which is commercially available 
from B.F. Goodrich and ULTRAMARINE BLUE which is commercially available 
from Whiftaker Chemical. Generally, the amount of dye on an aqueous basis 
can be about 1 to about 5 weight percent, and more preferably about 1 to 
about 3 weight percent. Users of the treated strand may find dyed strand 
useful for various applications where color coding is important. 
The secondary aqueous coating composition can also include one or more 
aqueous dispersible or soluble plasticizers. Examples of suitable 
non-aqueous-based plasticizers which are aqueous dispersible plasticizers 
include phthalates, such as di-n-butyl phthalate; trimellitates, such as 
trioctyl trimellitate; and adipates, such as dioctyl adipate. An example 
of an aqueous soluble plasticizer is CARBOWAX 400, a polyethylere glycol 
which is commercially available from Union Carbide of Danbury, Conn. The 
amount of plasticizer generally can be about 5 to about 15 weight percent 
of the secondary aqueous coating composition on a total solids basis, and 
is more preferably about 5 to about 10 weight percent. 
Water (preferably deionized) is included in the secondary aqueous coating 
composition in an amount sufficient to facilitate application of a 
generally uniform coating upon the strand. Generally, the weight 
percentage of solids of the secondary aqueous coating composition can be 
about 10 to about 50 weight percent. Preferably, the weight percentage of 
solids is about 20 to about 35 weight percent and, more preferably, about 
25 to about 35 weight percent. Although not preferred, it should be 
understood that minor amounts of water miscible or water soluble organic 
solvents can be included in the secondary aqueous coating composition, so 
long as the essential characteristics of the coating composition are not 
adversely affected. 
The secondary aqueous coating composition of the present invention can be 
prepared by any suitable method well known to those of skilled in the art. 
Preferably, the first polymer is formed by addition polymerization of the 
monomer component. Similarly, the second polymer is formed by addition 
polymerization of the monomer component. Each of the first polymer and the 
second polymer is preferably diluted with deionized water before mixing 
with the other components. 
The first and second polymers can be mixed and/or reacted with any other 
components of the secondary aqueous coating composition, such as 
emulsifiers, dye, wax and/or water. Preferably each of the components is 
diluted with water prior to addition to the mixture. If necessary, the 
plasticizer or lubricant can be pre-emulsified prior to addition to the 
mixture. The components of the composition are then mixed to form a 
generally homogenous mixture prior to application to the strand. While the 
composition is being applied to the strand, it is preferred that the 
composition be agitated for 1 minute out of every 10 minutes of 
recirculating when being recirculated through a holding tank. 
Before application of the secondary coating composition, the glass fibers 
are treated with a sizing composition, such as are discussed above, or 
fiber protectant to reduce interfilament abrasion. The secondary aqueous 
coating composition of the present invention can be applied to any type of 
fiberizable glass composition known to those skilled in the art. Glass 
fibers suitable for use in the present invention include those prepared 
from fiberizable glass compositions such as "E-glass", "621-glass", 
"A-glass", "C-glass", "D-glass", "S-glass", "ECR-glass" (corrosion 
resistant glass) and fluorine and/or boron-free derivatives thereof. Such 
compositions are well known to those skilled in the art and are disclosed 
in Loewenstein at pages 29 and 33-45, which is hereby incorporated by 
reference. 
The secondary coating composition of the present invention is applicable to 
high modulus, low elongation (a modulus of elongation of at least 
7.times.10.sup.6 psi and an elongation at break of at most 5 percent) 
fibers or filaments, preferably sized glass fibers. 
The sizing can be applied in many ways; such as by contacting the strand 
with a roller or belt applicator, spraying, or other means. Non-limiting 
examples of such applicators and other suitable applicators are disclosed 
in Loewenstein at pages 169-177, which is hereby incorporated by 
reference. 
The sized fibers can be dried at room temperature or at elevated 
temperatures. Suitable ovens for drying glass fibers are well known to 
those of ordinary skill in the art. Drying of glass fiber forming packages 
or cakes is discussed in detail in Loewenstein at pages 224-230, which is 
hereby incorporated by reference. For example, the forming package can be 
dried in an oven at a temperature of about 104.degree. C. (220.degree. F.) 
to about 149.degree. C. (300.degree. F.) for about 10 to about 13 hours to 
produce glass fiber strands having a dried residue of the curable 
composition thereon. The temperature and time for drying the glass fibers 
will depend upon such variables as the percentage of solids in the sizing 
composition, components of the sizing composition and type of glass fiber. 
The sizing is present on the fibers in an amount between about 0.5 percent 
and 5 percent by weight after drying. After drying, the sized glass fibers 
are typically gathered together into bundles or strands of generally 
parallel fibers and further treated with the secondary aqueous coating 
composition of the present invention. 
The secondary aqueous coating composition of the present invention is 
applied to at least a portion of the surface of the strand in an amount 
effective to coat or impregnate the portion of the strand. The secondary 
aqueous coating composition can be applied by dipping the strand in a bath 
containing the composition, by spraying the composition upon the strand or 
by contacting the strand with an applicator such as a roller or belt 
applicator, for example. The coated strand can be passed through a die to 
remove excess coating composition from the strand. The method and 
apparatus for applying the secondary aqueous coating composition to the 
strand is determined in part by the configuration of the strand material. 
Preferably, the process of applying the secondary aqueous coating 
composition includes passing the strands through a bath or dip of the 
secondary aqueous coating composition and preferably includes exposing the 
fibers to elevated temperatures for a time sufficient to at least 
partially dry or cure the secondary aqueous coating composition. The 
strand can be "opened up" just before entering the secondary treating 
composition bath by passing it over a bar or other spreading device which 
acts to separate the individual fibers from one another. This spreading of 
the fibers from one another results in a more thorough impregnation of the 
strand with the composition. 
The amount of the secondary aqueous coating composition on the strand is 
defined as the dip pick-up (DPU). The DPU is calculated using the weight 
of the glass strand before and after the secondary aqueous coating 
composition is applied. The DPU is defined as the coated strand weight 
minus the uncoated strand weight, then divided by the uncoated strand 
weight. Multiplying the resultant figure by 100 results in percent DPU. 
The DPU of the impregnated bundles or strands of the instant invention is 
about 5 to about 20 weight percent for a single pass through the 
impregnant bath and drying step. The strands may ultimately have an amount 
of coating greater than about 30 weight percent by passing them through 
the impregnating bath a number of times or by overcoating the coated 
bundle of fibers or strands with the secondary coating composition. 
Preferably, the strand having the dried residue of the secondary aqueous 
coating composition thereon typically has a dip pick-up (DPU) of between 
about 5 to about 30 weight percent, and preferably about 8 to about 15 
weight percent. 
The strand is preferably dried after application of the secondary aqueous 
coating composition in a manner well known in the art. The impregnated 
strand is at least partially dried in air at room temperature (about 
25.degree. C.) or alternatively in a furnace or oven preferably above 
232.degree. C. (450.degree. F.) to speed the curing process and evaporate 
the water. A particularly suitable drier is that disclosed in U.S. Pat. 
No. 5,197,202, which is hereby incorporated by reference. 
After the sizing and secondary coating composition have been applied to the 
glass strand and each layer has been dried, additional coatings, such as a 
tertiary coating composition, can be applied to at least a portion of the 
strand. In one embodiment, the tertiary coating composition includes one 
or more acrylic polymer(s) such as are discussed above, which is different 
from one of the acrylic polymers of the secondary coating composition. 
Preferably, the tertiary coating composition includes an ethylene acrylic 
acid copolymer, such as MICHEM.RTM. PRIME 4983HS aqueous ethylene acrylic 
acid copolymer emulsion. MICHEM.RTM. PRIME 4983HS has about 35 weight 
percent solids. 
Preferably the acrylic polymer comprises about 0.5 to about 5 weight 
percent of the tertiary coating composition, and more preferably about 1 
weight percent. The tertiary coating composition can also include an 
antistatic agent such as is discussed above. 
The tertiary coating composition generally includes about 10 to about 40 
weight percent solids, and preferably about 20 to about 30 weight percent. 
The tertiary coating composition can be applied in a manner similar to 
that of the secondary coating composition discussed above. 
The tertiary coating composition can be dried in air, a furnace or oven, as 
discussed above, although it is preferred to dry the coating in air. The 
strand having the dried residue of the tertiary coating composition 
thereon can have a dip pick-up (DPU) of between about 5 to about 30 weight 
percent, and preferably about 8 to about 15 weight percent. 
The coated strand is incorporated as reinforcement in an optical fiber 
cable assembly (shown in FIG. 1). The optical fiber assembly 10 can also 
include a protective layer 24 positioned about at least a portion of a 
periphery of the optical fiber 12 and reinforcement strand 14. Typically, 
the protective layer 24 comprises a thermoplastic material extruded as a 
jacket over the other components of the assembly 10. Suitable 
thermoplastic materials include polyethylene and polyvinyl chloride. The 
protective layer 24 protects the assembly 10 from damage from the 
environment. 
When this protective layer 24 is breached, or at splices or joints in the 
optical fiber cable assembly, water can enter the interior of the 
assembly, possibly causing corrosion of the optical fibers. Also, freezing 
temperatures can cause the water to freeze and expand, thereby crushing 
the optical fibers. It is important that the reinforcement strand of glass 
fibers simply and economically inhibit wicking or capillary movement of 
water through or along the strand and inhibit contact of water with the 
optical fibers. 
The water wicking of a coated strand can be determined by a water wicking 
test, such as the BellCore water wicking test No. TR-NWT-00492 (a test 
method of AT&T) or "Test Procedures for Wicking and Hygroscopicity", a 
technical bulletin of Superior Cable Corporation, which is hereby 
incorporated by reference. 
The water wicking of a coated strand can also be determined by the 
following method, which will generally be referred to herein as the "Water 
Wicking Estimation Method". An aqueous solution including a dye indicator 
is placed in a suitable container, such as a conventional beaker which is 
commercially available from Fisher Scientific, and a sample of a 
reinforcing strand is inserted into the solution such that about 2.54 
centimeters (1 inch) of the strand is below the surface of the solution 
and about 15.24 centimeters (6 inches) is above the surface. 
The surface area of the solution should be large enough such that the sides 
of the container do not unduly influence the wicking of the strand. 
Preferably, the dye is Imperon Blue Dye which is commercially available 
from Hoechst Celanese of Charlotte, N.C. Other useful dyes include inks 
and any number of conventional dyes known to those skilled in the art. The 
wicking of the strand can be measured by measuring the distance which the 
dye wicks along the strand above the surface of the solution. The wicking 
test should be conducted at about 25.degree. C. (77.degree. F.) for at 
least about 6 hours. 
Under such test conditions, the coated strand of the present invention 
wicks water at a rate of less than about 25.4 millimeters (one inch) in 
about six hours at a temperature of about 25.degree. C. and preferably 
less than about 12.7 millimeters (0.5 inches). 
The present invention also provides a method of reducing the wicking of 
water along the surface of a glass fiber strand comprising a plurality of 
glass fibers. The method comprises a first step of applying an aqueous 
sizing composition to surfaces of the plurality of glass fibers, which is 
discussed above. The sized glass fibers are at least partially dried, 
preferably in an oven at temperatures and for a period of time as 
discussed above. The plurality of dried glass fibers is then gathered to 
form a strand. The aforementioned secondary coating composition is applied 
to the strand, as discussed above. The secondarily coated strand is at 
least partially dried, such that the surface of the strand having thereon 
the dried residue of the secondary aqueous coating composition wicks water 
at a rate of less than about 25.4 millimeters (one inch) in about six 
hours at a temperature of about 25.degree. C., as discussed above. 
The present invention will now be illustrated by the following specific, 
non-limiting examples. 
EXAMPLE 1 
Ten gallon mixtures of the aqueous sizing compositions of Tables 1 and 2 
were prepared, applied to 2 strand bundles of H-15 E-glass fibers (1600 
filaments per strand) and wound onto individual forming packages in a 
manner similar to those discussed above. The weight of sizing composition 
on the fibers after drying the forming package at a temperature of about 
100.degree. C. for about 10 hours was about 0.7 weight percent. 
TABLE 1 
______________________________________ 
Component for Sample No. 1 
Weight Percent of Component 
______________________________________ 
PLURACOL V-10 polyoxyalkylene 
78 
pollyol.sup.1 
EMERY 6717 partially amidated 
8 
polyethylene imine lubricant.sup.2 
A-1108 aminosilane.sup.3 
14 
______________________________________ 
TABLE 2 
______________________________________ 
Weight of Component 
(grams) for Sample No. 
Component 2 3 4 
______________________________________ 
PLURACOL V-10 polyoxyalkylene polyol.sup.4 
300 300 1500 
FULATEX .RTM. PN-3716L1.sup.5 
2400 -- -- 
FULATEX .RTM. PN-3716G.sup.6 
-- 2500 -- 
LE-9300 silicone emulsion.sup.7 700 
EMERY 6717 partially amidated 
-- -- -- 
polyethylene imine lubricant.sup.8 
EMERY 6760 lubricant.sup.9 
412 412 412 
AIRVOL 205.sup.10 polyvinyl acetate 
700 -- -- 
A-1108 aminosilane.sup.11 
150 150 150 
A-174 silane.sup.12 150 150 150 
acetic acid 15 15 15 
______________________________________ 
.sup.1 PLURACOL V10 polyoxyalkylene polyol is commercially available from 
BASF Wyandotte of Michigan. 
.sup.2 EMERY 6717 partially amidated polyethylene imine lubricant is 
commercially available from Henkel Corporation of Kankakee, Illinois. 
.sup.3 A1108 aminosilane is commercially available from OSi Specialties, 
Inc. of Danbury, Connecticut. 
.sup.4 PLURACOL V10 polyoxyalkylene polyol. 
.sup.5 FULATEX .RTM. PN3716L1 acrylic multipolymer having about 44 to 
about 46 weight percent solids weight percent solids is commercially 
available from H. B. Fuller Co. of St. Paul, Minnesota. FULATEX .RTM. 
PN3716L1 is believed to include about 45 weight percent butyl acrylate, 5 
weight percent styrene and less than about 1 weight percent butyl methyl 
acrylate. 
.sup.6 FULATEX .RTM. PN3716G acrylic multipolymer is commercially 
available from H. B. Fuller Co. of St. Paul, Minnesota. FULATEX .RTM. 
PN3716G acrylic multipolymer is believed to include about 42 weight 
percent butyl acrylate and about 58 weight percent styrene. 
.sup.7 LE9300 silicone emulsion has about 50 weight percent solids and is 
commercially available from OSi Specialties, Inc. of Danbury, Connecticut 
.sup.8 EMERY 6717 partially amidated polyethylene imine lubricant is 
commercially available from Henkel Corporation of Kankakee, Illinois. 
.sup.9 EMERY 6760 lubricant is commercially available from Henkel 
Corporation. 
.sup.10 AIRVOL 205 polyvinyl acetate is commercially available from Air 
Products and Chemicals of Trexlertown, Pennsylvania. 
.sup.11 A1108 gammaaminopropyltrimethoxysilane is commercially available 
from OSi Specialties, Inc. of Danbury, Connecticut. 
.sup.12 A174 silane is commercially available from OSi Specialties, Inc. 
of Danbury, Connecticut. 
TABLE 3 
______________________________________ 
Weight of Component (grams) 
for Sample 
Component A B C D 
______________________________________ 
RHOPLEX .RTM. NW-1715.sup.1 
1000 1000 1000 1000 
acrylic polymer 
ROVENE .RTM. 5550.sup.2 styrene- 
100 -- -- -- 
butadiene copolymer 
FULATEX .RTM. PN-3716G.sup.3 
-- -- 100 -- 
styrene-acrylic copolymer 
FULATEX .RTM. PN-3716J.sup.4 
-- -- -- 100 
styrene-acrylic copolymer 
FULATEX .RTM. PN-3716L1.sup.5 
-- 100 -- -- 
styrene-acrylic copolymer 
PETROLITE 75 100 50 50 50 
microcrystalline wax.sup.6 
Deionized water 
850 850 850 850 
______________________________________ 
.sup.1 RHOPLEX NW1715 anionic acrylic polymer emulsion having a glass 
transition temperature of about -60.degree. C., about 44 percent solids a 
density of about 8.4 lb/gallon and a pH of about 6.2 is commercially 
available from Rohm and Haas Company of Philadelphia, Pennsylvania. 
.sup.2 ROVENE .RTM. 5550 is a selfcrosslinking anionic carboxylated 
styrene butadiene copolymer emulsion having about 45 weight percent 
styrene and 55 percent butadiene which is commercially available from Roh 
and Haas Company. 
.sup.3 FULATEX .RTM. PN3716G is commercially available from H. B. Fuller 
Co. of St. Paul, Minnesota. 
.sup.4 FULATEX .RTM. PN3716J acrylic multipolymer having about 44 to abou 
46 weight percent solids is commercially available from H. B. Fuller Co. 
.sup.5 FULATEX .RTM. PN3716L1 acrylic multipolymer is commercially 
available from H B. Fuller Co. 
.sup.6 PETROLITE 75 microcrystalline wax dispersion is commercially 
available from the Petrolite Corporation of Tulsa, Oklahoma. 
The secondary aqueous coating compositions were applied to the sized glass 
fibers by drawing the glass fibers through a bath of the coating and a die 
to remove excess coating, such that the loss on ignition (LOI) of the 
coated glass strand was about 8 to about 12 percent. The diameter of the 
passage through the die for the 4 strand samples prepared was about 1.1 
millimeters (0.044 inches). 
A. Wicking Evaluation 
Each coated strand was evaluated for wicking of water along the strand 
using the Water Wicking Estimation Method discussed above. A conventional 
500 milliliter plastic beaker was filled with about 250 milliliters of a 1 
weight percent aqueous solution of Imperon Blue Dye, which is available 
from Hoechst Celanese. An approximately six inch long sample of each 
strand was individually inserted into the solution to a depth of about 
25.4 millimeters (1 inch). The sample was supported by a thin sheet of 
plastic about 1 inch wide and about 6 inches in length positioned 
approximately in the center of the beaker. Each sample was kept in the 
solution for at least 6 hours at a temperature of about 25.degree. C. 
(77.degree. F.). A sample of a glass fiber strand believed to be 
commercially available from Owens Corning Fiberglas (OCF) was also tested 
in this manner. It is believed that the coating on this strand included 
ethyl acrylate, ethylene methyl acrylate, styrene, and less than about 0.1 
weight percent of alpha-methyl styrene. 
To pass this test, the strand must wick less than about 25.4 millimeters 
(one inch) in about six hours at a temperature of about 25.degree. C. The 
results of this test for each sample are set forth below in Table 4. 
TABLE 4 
______________________________________ 
Sizing Secondary Coating OCF 
Composition 
A B C D Sample 
______________________________________ 
1 PASS PASS PASS PASS FAIL 
2 PASS PASS PASS PASS 
3 PASS PASS PASS PASS 
4 FAIL FAIL FAIL FAIL 
______________________________________ 
As shown in Table 4, the secondary coating compositions of the present 
invention provide acceptable wicking resistance when evaluated using the 
Water Wicking Estimation Method, except for the Samples which included 
Sizing Composition No. 4. 
It appears that LE-9300 silicone emulsion, which was included in Sizing 
Composition No. 4, facilitates wicking. Therefore, as discussed above, it 
is preferred that the sizing composition applied to the glass fibers prior 
to secondary coating be essentially free of such a silicone emulsion. 
B. Other Physical Properties 
Five specimens each of strand coated with the aqueous secondary coating 
compositions of Table 3 were conditioned at about 24.degree. C. 
+/-2.degree. C. (75.degree. F. +/-5.degree. F.) at about 55% +/-5% 
relative humidity for at least two hours and evaluated for tensile 
breaking strength (pounds-force or lb.sub.f) using a drum clamp test 
fixture on an Instron Model No. 1125 testing machine. The chart speed was 
25.4 millimeters/minute (1 inch/minute), the crosshead speed was 304.8 
millimeters/minute (12 inches/minute) and the load was 453.6 kilograms 
(1000 lbs.). 
The relative resistance to bending was evaluated for five test specimens 
each of strand coated with the aqueous secondary coating compositions of 
Table 3 using a MIT Folding Endurance Tester Model #2, which is 
commercially available from Tinius Olsen Testing Machine Co. of Willow 
Grove, Pa. Each test specimen was 15.24 centimeters (6 inches) in length. 
Each specimen was conditioned at about 23.degree. C. +/-2.degree. C. 
(73.4.degree. F. +/-3.6.degree. F.) for at least 2 hours prior to testing. 
A 1.52 mm (0.06 inch) jaw, 2 lb. load and spring No. 4 were used to 
evaluate the number of cycles to failure. See also ASTM Standard D-2176. 
Two five yard skein specimens of strands coated with the aqueous secondary 
coating compositions of Table 3 were evaluated for percentage of 
outgassing at 250.degree. C. and loss on ignition (LOI), which is the 
weight loss of coating on the glass strand after heating at about 
650.degree. C. (about 1200.degree. F.). 
Two five yard skein specimens of strand coated with the aqueous secondary 
coating compositions of Table 3 were evaluated for loss on ignition (LOI), 
which is the weight loss of coating on the glass strand after heating at 
about 650.degree. C. (about 1200.degree. F.). 
Each specimen was weighed at a temperature of about 23.degree. C. 
+/-2.degree. C. (73.4.degree. F. +/-3.6.degree. F.) at a relative humidity 
of about 55% +/-5%. The specimens were heated in a conventional muffle 
furnace to a temperature of about 650.degree. C. (about 1200.degree. F.) 
for about 30 minutes, cooled to room temperature and reweighed. 
The results of the evaluations for average tensile breaking strength, 
outgassing at 250.degree. C., average cycles to failure (MIT folding test) 
and loss on ignition (LOI) for strands coated with the aqueous secondary 
coating compositions of Samples A-D of Table 3 are set forth in Table 4. 
Table 5 shows that samples including the secondary coating composition of 
the present invention have good tensile strength and flexibility. 
TABLE 5 
__________________________________________________________________________ 
Sizing Composition and Secondary Coating Composition 
TEST 1A 2A 3A 1B 2B 3B 1C 2C 3C 1D 2D 
__________________________________________________________________________ 
Average Tensile 
102 135 118 98 139 123 111 135 110 99 136 
Strength (lb.sub.f) 
Average Percent 
1.24 
0.91 
1.14 
2.30 
1.37 
1.5 2.05 1.38 
1.85 
1.8 1.34 
Outgassing at 
250.degree. C. 
Average MIT 
1500 
-- 6000 
6800 
-- 2100 
12000 
1500 
3500 
13000 
-- 
Folding Flexibility 
(cycles to failure) 
Average Loss on 
8.6 7.8 -- 12.4 
8.4 -- 10.5 8.1 -- 11.6 8.4 
Ignition (%) 
__________________________________________________________________________ 
EXAMPLE 2 
Several glass fiber strands were sized with the sizing compositions of 
Samples 1 or 2 of Example 1 and coated with secondary coatings believed to 
be according to the present invention in a manner similar to that 
disclosed in Example 1 above. The formulations for the secondary coatings 
are set forth in Table 6 below. 
TABLE 6 
__________________________________________________________________________ 
Weight of Component (grams) for Sample 
Component E F G H I J K L M 
__________________________________________________________________________ 
RHOPLEX .RTM. NW-1715.sup.1 
1360 
1360 
500 
1000 
1000 
1000 
1000 
1000 
1000 
acrylic polymer 
ROVENE .RTM. 5550.sup.2 styrene 
300 
500 
100 
100 
100 
100 
200 
300 
400 
butadiene copolymer 
RHOPLEX .RTM. E-32 acrylic 
440 
220 
500 
-- -- -- -- -- -- 
polymer.sup.3 
EL-9300 silicone 
-- -- -- -- -- 50 -- -- -- 
emulsion.sup.4 
PETROLITE 37 
100 
100 
50 50 -- -- -- -- -- 
microcrystalline wax.sup.5 
__________________________________________________________________________ 
.sup.1 RHOPLEX .RTM. NW1715 anionic acrylic polymer emulsion is 
commercially available from Rohm and Haas Company. 
.sup.2 ROVENE .RTM. 5550 selfcrosslinking anionic carboxylated styrene 
butadiene copolymer is commercially available from Rohm and Haas Company. 
.sup.3 RHOPLEX .RTM. E32 acrylic polymer having about 46 weight percent 
solids is commercially available from Rohm and Haas Company. 
.sup.4 LE9300 silicone emulsion has about 50 weight percent solids and is 
commercially available from OSi Specialties, Inc. of Danbury, Connecticut 
.sup.5 PETROLITE 37 microcrystalline wax dispersion is commercially 
available from the Petrolite Corporation of Tulsa, Oklahoma. 
Deionized water was added to each sample to adjust the solids to about 30 
percent by weight. 
Each Sample was evaluated for outgassing at 250.degree. C. using the method 
set forth above in Example 1. Table 7 below provides the outgassing values 
at 250.degree. C. for each Sample. 
TABLE 7 
______________________________________ 
Outgassing 
Weight of Component (grams) for Sample 
at 250.degree. C. 
E F G H I J K L M 
______________________________________ 
Sizing -- -- 0.98 0.87 0.65 0.72 0.97 0.94 0.96 
Composition 
Sizing -- -- 0.74 0.74 0.52 0.51 0.72 0.72 0.73 
Composition 
2 
______________________________________ 
As shown in Table 7, the outgassing values for glass fiber strands coated 
with secondary coating compositions of the present invention are extremely 
low and indicate that such coated strands can provide low gas void 
formation when the protective layer is extruded over the coated strands. 
EXAMPLE 3 
Glass fiber strand, which was sized with the sizing composition of Sample 1 
and coated with the secondary coating of Sample A according to Example 1, 
was overcoated with about 25 weight percent solids MICHEM.RTM. PRIME 
4983HS ethylene acrylic acid copolymer in deionized water to yield a dried 
residue upon the strand of about 1 weight percent as an overcoat. The 
Control was not overcoated. The loss on ignition of the strand was about 9 
weight percent without the tertiary coating. The strand having the 
tertiary coating applied thereto had a loss on ignition of about 10 weight 
percent. 
The average tensile breaking strength (with and without soaking in aqueous 
solutions of hydrochloric acid or sodium hydroxide), average tensile 
stiffness, average composite tensile modulus, percent outgassing, loss on 
ignition (LOI) and adhesion to polyvinyl chloride were evaluated for the 
overcoated and non-overcoated samples. 
To determine the tensile stiffness and composite tensile modulus of each 
specimen, three 10 yard skein specimens of strands coated with the aqueous 
secondary coating compositions of each of the samples were conditioned 
under similar conditions to those set forth above for tensile breaking 
strength testing. Each specimen was weighed and measured for specific 
gravity using a Fisher-Young gravitometer Model No. 2-148. Each specimen 
was evaluated for tensile stiffness and composite tensile modulus using 
pneumatic grips on an Instron Model No. 1125 testing machine. The Instron 
machine was set to Range 2 (Strain Data Unit) (which provides a 
magnification ratio of 1000), the crosshead speed was 5.1 
millimeters/minute (0.2 inches/minute) and the full scale chart load was 
45.4 kilograms (kg) (100 lbs.) or 22.7 kg (50 lbs.) load on the specimen. 
The average adhesion of each strand in high density polyethylene or 
polyvinyl chloride was determined according to ASTM D1871-68, which was 
modified as follows. Seven specimens of each sample were prepared, each 
specimen being about 30.48 centimeters (12 inches) to about 76.2 
centimeters (30 inches) in length. 
Fourteen specimens were prepared for testing at a time by the following 
method. The platens of the press were preheated to about 182.degree. C. 
(360.degree. F.). A 10.16 centimeter (4 inch) by 25.4 centimeter (10 inch) 
sheet of MYLAR.RTM. polyester film, which is commercially available from 
E.I. du Pont de Nemours et Cie & Company of Wilmington, Del., was placed 
in the mold cavity of the bottom plate of a heated press. The strand 
cavity in the bottom plate was placed on the MYLAR.RTM. film with a 1 inch 
insert. About 40 grams of solid thermoplastic molding stock (high density 
polyethylene or polyvinyl chloride) was placed generally uniformly in the 
mold cavity. The polyvinyl chloride (757C) and high density polyethylene 
are both available from AT&T. 
A knot was tied in each test specimen, which was placed in the cavity with 
the knot positioned outside of the cavity. Strand tension weights were 
attached to the end of each test specimen to align each strand straight in 
the mold. Fourteen specimens were accommodated in the molding. An 
additional 40 grams of stock was placed over the strands for a total of 
about 80 +/-0.5 grams of stock per molding. A sheet of MYLAR.RTM. film was 
placed over the stock, and the top plate placed upon the mold. 
The mold was placed in the press at a clamp pressure of less than about 1 
ton until the platen temperature returned to about 182.degree. C. 
(360.degree. F.). When the platen temperature reached about 182.degree. C. 
(360.degree. F.), the pressure upon the mold was increased to about 10 
tons for about 5 minutes. The platen heaters were turned off and cooling 
water turned on for about five minutes, then the molding was removed from 
the press. 
The MYLAR.RTM. film was stripped from the samples and the strand and 
flashing on the knot side of the molding were cut flush with the molding 
edge. The flashing from the other side of the molding was also removed. 
Each sample was tested for the force necessary to pull the strands 
linearly out of the molding stock according to ASTM D-1871-68. 
The results of testing conducted similarly to Example 1 above for average 
tensile breaking strength, average tensile stiffness, average composite 
tensile modulus, percent outgassing, loss on ignition (LOI) and adhesion 
to polyvinyl chloride are set forth in Table 8. 
Also included in Table 8 are results from tensile strength testing of 
samples soaked in (1) 1 normal aqueous solution of hydrochloric acid at 
about 24.degree. C. (75.degree. F.) for about 3 hours; or (2) 1 molar 
aqueous solution of sodium hydroxide at about 24.degree. C. (75.degree. 
F.) for about two minutes. Each sample was rinsed in water for about two 
minutes and dried at 120.degree. C. (250.degree. F.) for about 5-10 
minutes. 
TABLE 8 
______________________________________ 
Overcoated 
TEST Control.sup.1 
Sample.sup.2 
______________________________________ 
Average Tensile Strength (lb.sub.f) 
221 223 
Percent COV.sup.3 of Tensile Strength 
4.30 2.14 
Average Tensile Strength (lb.sub.f) after 
145 157 
Hydrochloric Acid Soak 
Percent COV of Tensile Strength after 
10.80 1.96 
Hydrochloric Acid Soak 
Percent Retention after Hydrochloric Acid 
72.5 78.5 
Soak 
Average Tensile Strength (lb.sub.f) after Sodium 
217 203 
Hydroxide Soak 
Percent COV of Tensile Strength after 
5.68 4.78 
Sodium Hydroxide Soak 
Percent Retention after Sodium Hydroxide 
109 102 
Soak 
Average Tensile Stiffness 
74.0 77.3 
(lb.sub.f /percent elongation) 
Average Tensile Modulus (lb.sub.f /inch.sup.2 .times. 10.sup.6) 
4.35 4.61 
Percent COV of Tensile Modulus 
1.3 1.6 
Average Percent Outgassing at 200.degree. C. 
0.501 0.691 
Average Percent Outgassing at 250.degree. C. 
1.23 1.27 
Average Loss on Ignition (%) 
10.1 11.1 
Average Adhesion to polyvinyl chloride (lb.sub.f) 
6.15 7.44 
Percent COV of Adhesion to polyvinyl 
19.3 25.2 
chloride 
Average Adhesion to high density 
13.4 22.4 
polyethylene (lb.sub.f) 
Percent COV of Adhesion to high density 
27.6 14.9 
polyethylene 
______________________________________ 
.sup.1 Four strand bundle. 
.sup.2 Four strand bundle. 
.sup.3 Coefficient of Variation. 
As shown in Table 8, the ethylene-acrylic acid overcoat has greater tensile 
strength after soaking in hydrochloric acid and greater adhesion to high 
density polyethylene when compared to the Control which does not include 
the overcoat. 
From the foregoing description, it can be seen that the present invention 
provides a simple, economical optical fiber cable assembly in which the 
reinforcement strand resists water wicking and is capable of withstanding 
the rigorous environment to which such reinforcement is subjected 
It will be appreciated by those skilled in the art that changes could be 
made to the embodiments described above without departing from the broad 
inventive concept thereof. It is understood, therefore, that this 
invention is not limited to the particular embodiments disclosed, but it 
is intended to cover modifications which are within the spirit and scope 
of the invention, as defined by the appended claims.