Note: Descriptions are shown in the official language in which they were submitted.
ASK,NDD(ASK)-8406
.
SPECIFICATION 2 ~ 8 0131
Water Shieldable Material and Cable Using the Same
TECHNICAL FIELD
The present invention relates to a water shieldable
material having superior water shieldability. More
particularly, the present invention relates to a water
shieldable material having superior water shieldability
for water having a lower ionicity as well as water having
a high ionicity such as a sea-water, for which it is
generaliy difficult to attain superior water
shieldability, and is capable of effectively being used
as a water shielding tape for a hold winding layer of, in
particular, an electrical wire cable or an optical fiber
cable. The present invention relates further to a cable
using the water shielding material.
PRIOR ART
In recent years, cables such as optical fiber cables
embedded in the ground have frequently been used.
Accordingly, characteristics required as a filler, such
~~ as, covering buffer properties preventing the core of a
communication cable from external force, an easy filling
ability depending on workability when manufacturing the
cable or the like are required of the cable, and in
addition to superior water shieldability. The water
shieldability is a property of absorbing rapidly water
flowing in a longitudinal direction of the cable and
shielding the water by a swell thereof, when a jacket of
the cable is broken and the water flows into the cable.
The T-letter method and L-letter method have been
used as methods of testing the water shieldability. The
T-letter method is a method of testing water flowing in
the longitudinal direction when an external force is
applied to the jacket of the cable and water flows
through holes or crocks generated by the external force
into the cable. The L-letter method is a method of
testi~g water flowing in the longitudinal direction from
~J ~
2 2Q~31~1
a cross section of the cable cut by an external force.
In both methods, the water shieldability is evaluated by
a length expressed in mm and after the water has flowed
into the cable for 24 hours. When the value representing
the length is small, it is determined that the cable has
superior water shieldability, and it is required that the
cable has superior value of the water shieldability in
the T-letter method and the L-letter method.
Japanese Unexamined Patent Publication (Kokai)
No. 63-6055 discloses a composite material having a water
swelling ability and comprised of a substrate of a
polyvinylpyrrolidine group binder, a dried film of which
has water-solubility and a water-soluble polymer coated
on the substrate. This composite material, however,
cannot be practically used because, since the binder is
water-soluble, the water-shieldable tape curls when there
is a change in humidity due to dimensional changes caused
by the substrate and the coating layer absorbing
moisture, and the tape becomes sticky when absorbing
moisture. Further this composite material has inferior
workability when manufacturing and applying the cable
because of the high level of hardness of the film
thereof.
Japanese Unexamined Patent Publication (Kokai)
No. 1-240547 discloses a water shieldable material
obtained by coating a surface of a woven fabric and a
nonwoven sheet with a rubber group binder and a high ion
water absorption composition. This type water shieldable
material made of a water absorption polymer composed of
particles having a small diameter has an inferior water
shieldability value as measured by the L-letter method
because the water absorption polymer does not drop away
from the surface of the nonwoven fabric and thus the
polymer swells on the surface of the nonwoven fabric, and
this type of water shieldable material made of a water
absorption polymer composed of particles having a large
diameter has an inferior water shieldability value as
20~3131
-- 3
measured by the T-type method because the density of the
coating layer composed of the rubber group binder and the
water absorption polymer is small. Accordingly, when,
for example, water shielding inside an optical fiber
cable takes place using this water shieldable material,
it is necessary to wind the water shieldable material on
the outside of the cable and in addition, insert a
tape-like material, made by cutting the water shieldable
material having a narrow width, into a slot i.e. a groove
in which a core wire is accommodated.
Japanese Unexamined Patent Publication (Kokai)
No. 2-183911 discloses a water shieldable material
obtained by coating a surface of a nonwoven sheet through
a peeling layer of a material selected from a group of
polyethylene and polypropylene with a water swelling
resin layer composed of a rubber group binder and a water
swelling resin. However, since the diameter of the
particles of the water swelling resin in the water
swelling resin layer is small, the water swelling resin
does not drop away from the resin layer in the water
~ shieldable material, and a water shielding operation is
performed by the water swelling resin layer peeled at the
peeling layer from the nonwoven fabric. Accordingly,
this water shieldable material also has inferior water
shieldability as measured by the T-type method and the
L-type method.
As previously described, a water shieldable material
having superior water shieldability features, in
particular water shieldability for a minute gap, a
non-curling property for various levels of moisture, a
stickproofing property, a covering buffer property, a
non-rotting property, easy workability when manufacturing
and applying the cable or the like has not yet been
devised.
DISCLOSURE OF THE INVENTION
The primary object of the present invention is to
solve,the problems of the conventional water shieldable
2Q~131
-- 4
material and to provide a water shieldable material
having superior water shieldability features, in
particular, water shieldability for a minute gap such as
a slot of a photofiber cable, a non-curling property for
various moisture levels, a stickproofing property, a
covering buffer property, a non-rotting property and
cable moldability.
The second object of the present invention is to
provide an electric wire cable and a opticalfiber cable
made of a water shieldable material in accordance with
the present invention.
The water shieldable material in accordance with the
present invention comprises a coating layer comprising a
rubber binder and a high water absorption polymer
particle having a specific diameter, and a solid
substrate supporting the coating layer is characterized
in that a density of the coating layer is determined to a
specific value.
Namely the primary object of the present invention
is attained by a water shieldable material comprising a
solid substrate and a coating layer arranged on the solid
substrate and comprising a high water absorption polymer
particle and a rubber group binder, characterized in that
the density of the coating layer is between 0.65 g/cm3
and 1.00 g/cm3; the ratio of a total weight o~ the high
water absorption polymer particle and the rubber group
binder in the coating layer is 90% by weight or more; the
weight ratio between the high water absorption polymer
particle and the rubber group binder is determined so
that the weight ratio of the high water absorption
polymer particle is a value between 50% by weight and 90%
by weight and the weight ratio of the rubber group binder
is a ~alue between 10% by weight and 50% by weight, and
the diameter of the particle belonging to the weight
ratio of between 55% by weight and g5% by weight in the
high water absorption polymer particle is between 45 ~m
20~131
and 425 ~m.
An electric wire cable or an optical fiber cable
attaining the second object of the present invention is
characterized in that the water shieldable material of
S the present invention is used as a water shieldable tape
for a hold winding.
Since the high water absorption polymer particle is
constituted as described herebefore, when the polymer
particles are not is contact with water, the polymer
particles do not drop away from the solid substrate, and
when the polymer particles are in contact with water, the
polymer particles swell rapidly and drop away from the
solid substrate in the water shielding material in
accordance with the present invention. And thus the
lS polymer particles spread separately each other in the
cable and can shield the water.
Since the size of the high water absorption polymer
particle, the density thereof and the ratio between the
high water absorption polymer particle and the rubber
group binder in the coating layer are suitably
determined, when the water flows therein, the high water
absorption polymer particle positioned where the water is
flowing swells rapidly, and thus superior water
shieldability as measured by the T-letter type method can
be attained. Further, the high water absorption polymer
particle drop away from a binder and can spread into a
slot, and thus superior water shieldability as measured
by the L-letter type method, i.e. a property thereby
preventing water from advancing can be attained.
Further, since the high water absorption polymer particle
is fixed on the solid substrate by the rubber group
binder in the coating layer, the polymer particle will
not drop away when connecting the cable and thus
workability is superior, and the water shieldable
material in accordance with the present invention has a
superior non-curling property for various moisture levels
and a superior stickproofing property. Further since a
- 6 - 2080131
non-aqueous rubber group binder having flexibility is
used, a covering buffer property, a non-rotting property
and cable molability when manufacturing and connecting
the cable can be realized.
BRIEF DESCRIPTION OF THE DRAWINGS
Figure 1 is an enlarged and schematical cross
sectional view of a water shieldable material in
accordance with the present invention;
Fig. 2 is an enlarged cross sectional view of a slot
type optical fiber cable in which the water shieldable
material in accordance with the present invention is used
as a water shieldable tape for a hold winding;
Fig. 3 is a micrograph, a magnification of which is
100, showing the shape of a fiber and the shape and size
of the high water absorption polymer particle in a cross
section of an example of the water shieldable material in
accordance with the present invention;
Fig. 4 is a micrograph, a magnification of which is
100, showing the shape of a fiber and the shape and size
of the high water absorption polymer particle on a
surface of the water shieldable material shown in Fig. 3;
Fig. 5 is a micrograph, a magnification of which is
100, showing the shape of a fiber and the shape and size
of the high water absorption polymer particle in a cross
section of another example of the water shieldable
material in accordance with the present invention;
Fig. 6 is a micrograph, a magnification of which is
100, showing the shape of fiber and the shape and size of
the high water absorption polymer particle on a surface
of the water shieldable material shown in Fig. 5;
Fig . 7 is a micrograph, a magnification of which is
100, showing the shape of a fiber and the shape and size
of the high water absorption polymer particle in a cross
section of a conventional water shieldable material;
Fig. 8 is a micrograph, a magnification of which is
100, showing the shape of a fiber and the shape and size
of the high water absorption polymer particle on a
2Q~0131
-- 7
surface of the high water absorption polymer particle
shown in Fig. 7;
Fig. 9 is a perspective view showing a connecting
portion of an L-letter tube used in the L-letter
measuring method, which is one method of evaluating the
water shieldability of the water shieldable material in
accordance with the present invention;
Fig. 10 is a cross sectional view of the L-letter
tube shown in Fig. 9;
Fig. ll is a perspective view showing a connecting
portion of a T-letter tube used in the T-letter measuring
method, which is one method of evaluating the water
shieldability of the water shieldable material in
accordance with the present invention.
BEST MODE FOR CARRYING OUT THE INVENTION
The present invention will be described hereinafter
in connection with the accompanying drawings showing an
example of a water shieldable material in accordance with
the present invention and an example of the optical fiber
cable in accordance with the present invention.
Fig. l shows, in model form, an enlarged cross
section of the water shieldable material in accordance
with the present invention.
As shown in Fig. l, a water shieldable material l in
accordance with the present invention comprises a solid
substrate 3 and a coating layer 2 arranged on the solid
substrate 3 and comprising a plurality of high water
absorption polymer particles 4 and a rubber group
binder 5. By determing definite values for the diameter
of the high water absorption polymer particle, the weight
ratio between the high water absorption polymer and the
rubber group binder and the density of the coating layer,
respectively, when the water shieldable material is in
contact with water, the high water absorption polymer
swells rapidly and thus drop away from the solid
substrate and as a result a water shielding operation can
be attained.
- 8 - 2Q~0131
In the water shieldable material in accordance with
the present invention, first it is required that the
diameter of the particle belonging to a weight ratio of
between 55% by weight and 95% by weight, preferably
between 80% by weight and 95% by weight in the high water
absorption polymer particle is between 45 ~m (mesh-on of
3300) and 425 ~m (mesh-pass of 36). When the water
shieldable material in accordance with the present
invention is in contact with water, the high water
absorption polymer particle can rapidly swell and be
removed from the binder to drop away from the solid
substrate, and thus the high water absorption polymer
particle can shield the water separately and superior
water shieldability is attained.
It seems that the high water absorption polymer
particle dropping away from the binder when in contact
with water in spite of the fact that the binder is
non-aqueous, is based on the fact that the diameter of
the high water absorption polymer particle is
sufficiently large, the polymer particle is arranged so
as to be enclosed with a thin membrane of the binder in
the coating layer, and continuous or discontinuous air
voids are arranged between the polymer particles, and
when the polymer particles are in contact with water ! the
high water absorption polymer particles swell
immediately, and at that time the membrane of the binder
is not capable of suppressing the swelling potential of
the high water absorption polymer particle.
When the diameter of the high water absorption
polymer particle is too small, the polymer particles are
enclosed in the coating layer and the air voids between
the polymer particles become extremely small.
Accordingly, when the water shieldable material is in
contact with water, a long time is required from the time
at which the water shieldable material is first in
contact with the water to the time at which the water is
actually in contact with the polymer particle and thus
X
9 2Q~0131
the swelling speed is lowered, further even if the
polymer particles swell, the polymer particles are not
capable of jumping off the coating layer and thus the
polymer particles cannot drop away and result in inferior
water shieldability. A preferable diameter of the high
water absorption polymer particle is between 45 ~m and
300 ~m, in view of the adhesiveness of the high water
absorption polymer particle to the solid substrate.
It is preferable that the high water absorption
polymer having a diameter of under 45 ~m is included when
the water shielding operation is applied to, for example,
minute gaps in a slot, such as a slot lOa in Fig. 2 of an
optical fiber cable. In this case, a weight ratio of the
particles having a diameter of under 45 ~m in all the
polymer particles must be under 45% by weight. If the
weight ratio is over 45% by weight, the swelling speed
becomes lower, and even if the polymer particle can
swell, the capability of dropping away from the coating
layer is lessened and results in inferior water
shieldability.
Figs. 3 to 8 are micrographs, a magnification of
which is 100, showing examples i.e., Examples 1 to 6 and
comparative example, i.e., Comparative Example 16 of the
water shieldable material in accordance with the present
invention, and Figs. 3, 5 and 7 are cross sectional views
and Figs. 4, 6 and 8 are plain views.
As can be seen from Figs. 3 and 5 showing the cross
sectional views of an example of the water shieldable
material in accordance with the present invention, a lot
of the high water absorption polymer particles having a
significantly large diameter compared with the thickness
of the water shieldable material are arranged in the
coating layer and a lot of air gaps can be found in
circumferential portions of each particle and each
particle group. Further, the presence of membranes of
the binder and many air voids can be found in Figs. 3 and
5, and Figs. 4 and 6, which are corresponding plain
2080131
views, respectivity. A fiber-like material in Figs. 4
and 6 is a fiber constituting a cover cloth, i.e., a
nonwoven fabric in this case, which is described in
detail hereinafter, and a solid substrate, i.e., a
nonwoven fabric in this case can be observed in the lower
side of the coating layer in Figs. 3 and 5.
A water shieldable material of Comparative
Example lb is shown in Fig. 7 (a cross sectional view)
and Fig. 8 (a plain view) and a high water absorption
polymer particle having a small diameter is used in this
case, but the cover cloth is not used.
A measurement of the diameter of a particle is taken
according to JIS Z 8815 i.e., a sieve analysis method,
using wire sieves according to JIS Z 8801 i.e., a
standard sieve. Namely, several sieves having a mesh
size corresponding to a particle diameter of a test
sample i.e., a high water absorption polymer is arranged
in order from the sieve having a large mesh to the sieve
having a small mesh, the test sample is put on the upper
most sieve, a pan is arranged on a position below the
lowest sieve and then vibration is applied to the set up
sieves under conditions according to JIS. After the test
sample is treated, the weight of each of the particles on
each sieve is measured and a particle size distribution
is calculated.
In the water shieldable material in accordance with
the present invention, a high water absorption polymer
particle having a dropping away ratio of 50% by weight or
more, with the measurement being taken after the water
shieldable material has been immersed for 10 minutes, is
preferably used. The dropping away ratio of the polymer
particle can be obtained by the water shieldable material
of 1 g being stationary and hanging in 1 litre of a
commercially supplied purified water, and the water
shieldable material being removed from the water after an
immersion time of 10 minutes and dried while maintaining
its form, and finally the weight of the residual polymer
- 11 2~0131
in the material being measured.
When the dropping away ratio of the high water
absorption polymer particle is under 50% by weight, since
the number of high water absorption polymer particles
dropping away is lessened, the water shieldability of
this material is inferior. For example, a coating liquid
is prepared by diluting and mixing 70 parts by weight of
a polymer particle having a particle diameter of 150 ~m
or less and sifted from KI gel 201K supplied from
Kurare Co., Ltd and having a 20 mesh pass of under 790 ~m
by using a sieve of 100 mesh, 0.7 parts by weight of
potassium octyl phosphate and 30 parts by weight of the
rubber group binder with an organic solvent such as
toluene, methyl ethyl ketone, ethyl acetate or the like.
This coating solution is uniformly coated on a polyester
spun bond E-5060, which is a polyester spun bond nonwoven
fabric supplied from Asahi Kasei Kogyo Kabushiki Kaisha
in such a manner that a pick up of the high water
absorption poly becomes 100 g/m2, and then the coated
material is dried. A 1 gram sample is prepared from the
above material, the sample is stationary and hanging in
1 litre of a commercially supplied purified water, and
the sample is taken out from the water after an immersion
time of 10 minutes and dried while maintaining its form,
and finally the weight of the residual polymer in the
sample is measured. The dropping away ratio of this high
water shieldable material is preferably 50% by weight or
more.
It is preferable that the water absorption
magnification of the high water absorption polymer in
accordance with the present invention and measured by
CB method described in detail hereinafter is ten times or
more. The water absorption magnification described
hereinafter is the water absorption magnification
measured by the CB method.
Since it is required that the high water absorption
2Q~0 131
- 12 -
polymer particle be individually separated upon coming
into contact with water and spread in a cable, the
polymer must have a particle-like shape. But the shape
of the particle is not limited to a specific shape and a
particle being, for example, perfectly round as obtained
by an emulsion polymerization, or having a distorted
shape ground at random by a grinder can be used.
As the high water absorption polymer, for example,
polyacrylonitrile graftpolymer hydrolyzate, sodium
polyacrylic acid, methyl methacrylic acid-vinyl acetate
copolymer hydrolyzate, polyvinyl alcohol hydrolyzate,
polyacrylonitrile crosslinked polymer hydrolyzate,
polyethylene oxide crosslinked polymer, polyacrylamide
crosslinked polymer, acrylamide-acrylic acid crosslinked
copolymer, sulfoalkyl(meta)acrylate-acrylic acid
crosslinked polymer, and isobutylene-maleic anhydride
crosslinked polymer can be preferably used. Further,
starch-polyacrylonitrile graft polymer hydrolyzate,
starch-acrylic acid graftcopolymer, carboxymethyl
cellulose hydrolyzate, cellulose-polyacrylonitrile graft
polymer hydrolyzate or the like, which generate hydrogen
gas when they are putrefied can also be used by applying
a putrefaction treatment.
Second, it is necessary to use a rubber-group binder
as a binder binding the high water absorption polymer
particle into the coating layer in the water shieldable
material in accordance with the present invention. It is
preferable that the rubber group binder is a binder that
can be solved by an organic solvent such as, for example,
toluene methyl ethyl ketone, ethyl acetate or the like,
can easily drop away the high water absorption polymer
particle from the water shieldable material when the
water shieldable material is in contact with water, is
capable of lending flexibility to the water shieldable
material and does not generate hydrogen gas by
putrefaction thereof.
~ s those rubber group binders, s~yrene-butadiene
2~80131
- 13 -
rubber, butadiene rubber, isoprene rubber, haloprene
rubber, isobutylene rubber, butyl rubber,
ethylene-polypropylene rubber, chlorosulfonated
polyethylene rubber, silicone rubber,
trifluoro-chloroethylene rubber, vinylidene-fluride
rubber, dihydro-perfluoro-alkylacrylate rubber,
polyurethane rubber, vinyl group rubber or the like can
be used and the styrene-butadiene rubber in the above
rubbers is preferably used. A styrene-butadiene rubber
obtained by block polymerizing styrene of 5% by weight or
more, preferably between 10% by weight and 40% by weight
is preferable in view of the adhesive force thereof to a
substrate, the holdability of a polymer when
manufacturing and laying the cable, the water
shieldability of the water shieldable material, the
covering buffer property, curling protection or the like.
A saturated type and an unsaturated type of a
styrene-butadiene rubber may be used, but the saturated
type styrene-butadiene rubber is preferable in terms of
durability. The styrene-butadiene rubber can be used
alone or by mixing two or more rubbers. Further the
styrene-butadiene rubber may be used with
styrene-butadiene rubber made by random polymerization,
butadiene rubber or the like.
Third, it is necessary that the ratio of the total
weight of the high water absorption polymer particle and
the rubber group binder in the coating layer be 90% by
weight or more, the density of the coating layer be
between 0.65 g/cm3 and 1.00 g/cm3, and the weight ratio
between the high water absorption polymer particle and
the rubber group binder be such that the weight ratio of
the high water absorption polymer particle is between 50%
by weight and 90% by weight, and the weight ratio of the
rubber group binder is between 10% by weight and 50% by
weight in the water shieldable material in accordance
with the present invention.
- 14 - 2 Q~a 13
Although another filler can be added to the high
water absorption polymer particle and the rubber group
binder in the coating layer, when the filler of 10% by
weight or more is added to the coating layer, the water
shieldability becomes inferior. A water shieldability of
the T-type method of the water shieldable material having
a coating layer with a density of under 0.65 g/cm3 is
inferior. Further water shieldability, especially the
L-type water shieldability having a coating layer with a
density of over 1.00 g/cm3 is also inferior.
A method of measuring the density of the coating
layer is as follows.
A micrograph, of a cross section of a water
shieldable material with a magnification of 100 is taken
by a microscope as shown in Fig. 1. The thickness (TiS)
of the solid substrate in the micrograph is measured and
the volume (Vs) per unit area is calculated on the basis
of the obtained thickness. Further, the weight (Ws) per
unit area of the solid substrate is measured. The
thickness (TiT) of the water shieldable material is
measured by a thickness tester and the volume (VT) per
unit area is calculated on the basis of the obtained
thickness. Further, the weight (WT) per unit area of the
water shieldable material is measured. The density of
the coating layer is calculated by the following
equation.
Pct = Wct / Vct
whereln:
PCt: a density of the coating layer (g/cm3)
Wct/Vct can be calculated by the following equations
Vs = TiS x A x B
wherein:
Vs: Volume of solid substrate (cm3)
TiS: Thickness of solid substrate (cm)
A: Width of solid substrate, i.e., water shieldable
material (cm)
- 15 - 2~01~1
B: Length of solid substrate, i.e., water
shieldable material (cm)
VT = T~-T X A X B
wherein:
VT: Volume of water shieldable material tcm3)
TiT: Thickness of water shieldable material (cm)
WCt = WT -- WS
wherein:
WCT: Weight of coating layer (g)
WT: Weight of water shieldable material (A X B) (g)
Ws: Weight of solid substrate (A X B) (g)
VCt = VT -- VS
wherein
VCt Volume of coating layer (cm3)
It is possible to obtain a coating layer having the
density of between 0.65 g/cm3 and 1.00 g/cm3 by
compressing a water shieldable material coated by a
conventional coating method by using a high pressure
calender.
The water shieldable material in accordance with the
present invention can have superior water shieldability
because the diameter of the high water absorption polymer
particle in the coating layer is between 45 ~m and
425 ~m, and the density of the coating layer is between
0.65 g/cm3 and 1.00 g/cm3. Even if the diameter of the
high water absorption polymer particle is under 45 ~, a
coating layer having a density of between 0.65 g/cm3 and
1.00 g/cm3 can be obtained, but the L-letter water
shieldability of the obtained water shieldable material
is inferior.
As described herebefore, it is necessary that the
weight ratio between the high water absorption polymer
particle and the rubber group binder be such that the
weight ratio of the high water absorption polymer
particle is between 50% by weight and 90% by weight, and
the weight ratio of the rubber group binder is between
- 2080131
10% by weight and 50% by weight in the water shieldable
material in accordance with the present invention. But
it is preferable that the weight ratio be between 70% by
weight and 85~ by weight for the high water absorption
polymer particle and between 15% by weight and 30% by
weight for the rubber group binder. When the weight
ratio of the high water absorption polymer particle is
under 50% by weight and the weight ratio of the rubber
group binder is over 50% by weight, the dropping away
ratio of the high water absorption polymer particle
becomes lower. When the weight ratio of the high water
absorption polymer particle is over 90~ by weight and the
weight ratio of the rubber group binder is under 10% by
weight, the holding property of the high water absorption
polymer particle is inferior and thus the polymer
particle may drop away from the coating layer before the
water shieldable material is in contact with the water.
Since the rubber group binder is hydrophobic, there
is a possibility that the binder will repel the water and
thus the water shieldability will be inferior. In this
case, it is possible to improve the water shieldability
by adding a hydrophilic agent such as an alkali metal
salt of alkylphosphate.
A material having superior durability and,
especially, that does not generate hydrogen gas by
putrefaction thereof can be used as a solid substrate
used in the water shieldable material in accordance with
the present invention. For example, a woven fabric, a
knitted fabric, a nonwoven fabric, a mesh-like woven
fabric, a mesh-like knitted fabric, a film or the like of
an acrylic group synthetic fiber, a polyester group
synthetic fiber, a polyamide group synthetic fiber, a
polypropylene group synthetic fiber or the like can be
used.
A method of manufacturing the water shieldable
material in accordance with the present invention will be
described hereafter.
- 17 _ 20~0131
The water shieldable material in accordance with the
present invention can be obtained by, for example,
coating a coating liquid prepared by uniformly dispersing
a high water absorption polymer into a rubber group
binder dissolved in an organic solvent to at least one
surface of a solid substrate, evaporating the organic
solvent and fixing the polymer to the substrate by
heating. When the quantity of the coating liquid is
excessive, the thickness of the water shieldable material
is excessive and problems arise thereupon. Accordingly,
it is preferable to control the thickness of the water
shieldable material by a high pressure calender press
machine or the like, which is useful for applying a
desired density to the coating layer.
The water shieldable material in accordance with the
present invention having a nonwoven sheet (referred to as
a cover cloth, hereafter) of a thermoplastic synthetic
fiber and having voids through which a distended water
absorption polymer particle may pass, a PVA film of water
solubility, or a parting agent of polymethylsiloxane on a
surface of the coating layer has an advantage because the
handling properties during treatment using the high
pressure calender press machine is superior. Namely, the
coating layer in the water shieldable material in
accordance with the present invention is held to the
solid substrate in such a manner that the high water
absorption polymer particles do not exit outward when the
water shieldable material is not in contact with the
water, in addition, an improvement in the slipperiness of
the surface of the water shieldable material and the ease
by which water shieldable material is handled is apparent
by providing the cover cloth or the like.
In the optical fiber cable, there is a possibility
that when the cable absorbs moisture in an environment
having a wide variation of moisture and the water
shieldable material becomes sticky, the water shieldable
material will adhere to an optical fiber tape in the
- 18 _ 2080131
optical fiber cable, and strain is generated in the
optical fiber cable because of the difference in the
longitudinal expansion coefficient between the optical
fiber cable and the water shieldable material thereby
resulting in a large electrical transmission loss in the
optical fiber cable. In the optical fiber cable using
the water shieldable material including the cover cloth,
adhesion of the water shieldable material to the cable
will not occur and thus an electrical transmission loss
will not occur.
The cover cloth can be prepared from a nonwoven
fabric having voids capable of passing the swelled
polymer particles, good durability with no probability of
generating hydrogen gas by putrefaction thereof. In
particular, it is preferable to use the nonwoven sheet of
a thermoplastic synthetic fiber. In this nonwoven sheet,
interlaced points formed by a plurality of fibers
constituting the nonwoven sheet are fused on each surface
and are arranged in random, and a plurality of the fibers
are bonded in a tongue-like shape or a web-like shape at
each interlacing point. When assuming the shape of a
void between the fibers formed by the interlacing points
is a polygon, it is preferable that the voids 50% or more
in all the voids of the nonwoven sheet is a void such
that the sum of the lengths of the sides of the void is
0.3 mm or more, and the voids of 90~ or more in all the
voids of the nonwoven sheet is a void such that the sum
of the lengths of the sides of the void is 5 mm or less.
The nonwoven sheet can be manufactured by stretching or
biaxially orienting a polyester spun bond nonwoven sheet
having a weight per unit area of 40 g/m2, while heating
and mixing a staple fiber of a synthetic fiber with a
thermal fusible fiber or applying the thermal bonding
method to the thermal fusible fiber.
When the PVA film is used for the same object as
that of the cover cloth, a lowering of the swelling speed
- 19 - 20~0131
of the water shieldable material in the water can be
improved by providing holes in a film. In this case, a
preperforated film may be used, or a hole may be
perforated on a film adhered on the water shieldable
material.
Fig. 2 shows an enlarged cross sectional view of a
slot and water run proofing type fiber cable using an
example of the water absorption tape in accordance with
the present invention. This cable comprises a tension
member 7 arranged on the most center position of the
cable as a core, a slot-type spacer 10 arranged around
the tension member 7 and including slots lOa, optical
fiber core tape 8 arranged in the slots lOa, optical
fibers 9 accommodating the optical fiber core tape 8, a
water shieldable tape 6 for a hold winding arranged
around the spacer 10 and made of the water shieldable
material, and a jacket ll. When cracks are generated in
the jacket ll and water flows into the cable, the high
water absorption polymer particle held in the water
shieldable tape 6 rapidly absorbs the water and swells,
_
and thus the polymer particles drop down into the slot
lOa and spread. Accordingly, the optical fiber cable
having the above-described constitution can prevent the
intrusion of water for a long period of time.
A water proofing of the optical fiber cables can be
attained by using the water absorption tape in accordance
with the present invention only as the hold winding water
shieldable tape 6.
The present invention will be described in detail by
the following examples. % and part used in the examples
refers to 96 by weight and part by weight.
Water aksorption magnification, putrefaction test,
water shieldability and a dropping away ratio
measurements in the examples are taken by the following
method.
(1) Water absorption magnification according to
CB method
2~0131
- 20 -
A test piece having a weight of X is immersed
into commercially supplied purified water at 23C for
1 hour, and then is placed into a tubular metal wire cage
of 300 mesh stainless steel and placed into the stainless
tube of a spin-drier for 10 minutes to remove the water.
The test piece with the cage is subjected to a water
removing operation with a force of 100 G for 1 minute.
The test piece is then removed from the spin-drier and
the weight (Y) of the test piece is measured. A value X
is the weight of the test piece obtained after the test
piece is dried at 105C in a hot air dryer until a change
in the weight of the test piece reaches zero. The water
absorption magnification (GB) of the test piece is
calculated according to the following equation.
When the water absorption magnification for
water having high ionicity is measured, artificial water
(Aquamarine supplied from Yasu Yakuhin Sha) is used in
place of the purified water.
Water absorption magnification = (Y - X)/X - 1
(2) Putrefaction test
A 4 g of test sample and 0.4 g of monoammonium
phosphate and 200 cc of a soil extraction liquid are
placed into a triangular glass flask. The flask is
closed with a cock, mixed and kept in the shade at 30C
for 30 days. The cock is then removed from the flask,
and 2 to 3 cc of the generated gas in the flask is
analyzed by a gas chromatography, and the color and state
of the liquid are observed visually.
Preparation of the soil extraction liquid is as
follows.
a) A soil sample is taken from a location
with fallen leaves and grass.
b) The soil sample of 500 g and 2000 cc of
pure water are placed in a vessel and mixed.
c) After 12 hours, a supernatant liquid is
filtered and 50 cc cf the filtered liquid is added to
1500 cc of water to prepare the soil extraction liquid.
20~01~1
- 21 -
d) The soil and the soil extraction liquid
should be newly prepared or extracted for each test
batch.
(3) Water shieldability
a) L-letter method
Fig. 9 shows a perspective view of an
apparatus for measuring water shieldability according to
the L-letter method, and Fig. 10 shows a cross sectional
view of a bar 16 used in the apparatus.
A groove, i.e., slot having a width of
1.6 mm and a depth of 2.0 mm runs in a longitudinal
direction of a 1.5 cm polyacetal cylindrical bar 16 as
shown in Fig. 10. Four sheets of optical fiber core
tapes 8 having a thickness of 0.4 mm and a width of
1.1 mm are accommodated in the groove of the bar 8. The
whole surface of the bar 16 is covered with a hold
winding water shieldable tape 6 and a sealing vinyl
tape 15 to form a body having a structure similar to an
optical fiber cable, i.e., modified cable. The modified
cable with opened ends is arranged horizontally, and an
opened end is connected through a rubber tube 13 to a
vertical glass tube 12 having an inner diameter of 10 mm.
Water is poured into the tube 12 such that the height of
the water in the vertical glass tube 12 is 1 m from the
position of the horizontal modified cable. After
24 hours, the amount of water in the water shieldable
tape in the modified cable is measured. If the amount of
water is small, the water shieldability of the water
shieldable material is considered good.
b) T-letter method
Fig. 10 shows a perspective view o~ an
apparatus for measuring water shieldability according to
the T-letter method.
A groove, i.e., a slot having a width of
1.6 mm and a depth of 2.00 mm runs along the longitudinal
direction of a polyacetal cylindrical bar having a
diameter of 1.5 cm and a length of 4 m, as shown in
- 22 - 2080131
Fig. 11. Four sheets of optical fiber core tapes having
a thickness of 0.4 mm and a width of 1.1 mm are
accommodated in the groove of the bar. The whole surface
of the bar is covered with a hold winding water
shieldable tape 6 and a sealing vinyl tape 15 to form a
body having a structure similar to an optical fiber
cable, i.e., a modified cable. The modified cable with
opened ends is arranged horizontally, and a portion of
the sealing vinyl tape 15 having a width of 2 cm at the
center of the bar, i.e., a point equally remote from both
ends is peeled. ~he modified bar is placed into a
tube 17 having a T-letter shape, a length of 10 cm and an
inner diameter of 1.8 cm, and the peeled portion is set
at a central portion of the T-letter tube. Both ends of
the T-letter tube are connected and sealed to the
modified cable by vinyl tape 18. A vertical portion of
the T-letter tube 17 is connected through a rubber
tube 13 to a glass tube 12 having an inner diameter of
10 mm. Water is poured into the glass tube such that the
height of the water in the glass tube is 1 m from the
position of the horizontal modified cable. After
24 hours, the amount of water in the water shieldable
tape in the modified cable is measured and if the amount
of water is small, the water shieldability of the water
shieldable material is considered good.
(4) Dropping away ratio
A test piece of the water shieldable material
having a definite area (S) is prepared, and the
weight (A) of the test piece is measured. The test piece
is immersed into commercially supplied purified water at
23C for 10 minutes. The test piece is then removed and
dried at 105C and the weight (B) of the dried test piece
is measured. Further, the weight of the water absorption
polymer (C) included in the definite area (S) of the
water shieldable material is calculated on the basis of
ratios of the high water absorption polymer and the
rubber group binder or the like and the dropping away
- 23 - 2 ~S 0 1 3
ratio is calculated from the following equation.
The values of A, B and C in the equation are
weights obtained after the test piece is dried in a hot
air dryer at 105C such that a change in the weight of
the test piece becomes zero.
Dropping away ratio (%) = (A - B)/C
Example 1
The following materials are mixed and uniformly
dispersed.
TUFDENE 1000 (stylenebutadiene group rubber)
supplied from Asahi Kasei Kogyo Kabushiki Kaisha
--- 15 parts
TUFPRENE A (Stylenebutadiene group rubber)
supplied from Asahi Kasei Kogyo Kabushiki Kaisha
lS --- 15 parts
KI gel 201K-F3 (isobutylene~maleic anhydride
crosslinked copolymer in which particles having a
diameter between 45 ~m and 425 ~m of 91% by weight
is included)
supplied from Kurare Kabushki Kaisha
_
--- 70 parts
Potassium octyl phosphate --- 0.7 parts
Toluene (used as a diluent) --- 90 parts
The dispersion liquid is coated on a polyester spun
bond E-5060 (polyester spun bond nonwoven fabric)
supplied from Asahi Kasei Kogyo Kabushiki Kaisha in such
a manner that the pick-up value of the high water
absorption polymer becomes 100 g/m2, and a coated
nonwoven fabric is dried. SMASH YR10 (polyester spun
bond nonwoven fabric having the weight per unit area of
10 g/m2) supplied from is placed on the coating layer of
the coated sheet, and is then treated with a high
pressure calender having a linear pressure of 70 kg/cm
and a temperature of 50C. The density of the obtained
coating layer is 0.76 g/cm3. The obtained water
shieldable material is cut to a water shieldable tape
- 20'30131
- 24 -
having a width of 2.5 cm. The water shieldability of the
obtained material is measured and the obtained results
are shown in Tables 1 and 2. As can be seen in Table 2,
the example has superior water shieldability in the
L-letter method and T-letter method. The workability in
cable connection and covering buffer properties of the
Example are superior, and the generation of a hydrogen
gas cannot be found in the putrefaction test.
Micrographs of the water shieldable material in Example 1
are shown in Fig. 3 (cross sectional view) and Fig. 4
(plain view).
Comparative Example la
A water shieldable material of Comparative
Example la is prepared using the same treatments as those
in Example 1, until the coating process and the drying
process. The density of the coating layer in this
Comparative Example la is 0.88 g/cm3.
The obtained material is slit with a tape having a
width of 2.5 cm and the water shieldability is measured.
The obtained results are shown in Figs. 1 and 2.
Workability in cable connection and covering buffer
properties of this Comparative Example are superior, and
the generation of a hydrogen gas cannot be found in the
putrefaction test. As shown in Table 2, the water
shieldability according to the L-letter method is
superior, but water shieldability according to the
T-letter method is inferior.
Comparative Example lb
A water shieldable material of Comparative
Example lb is prepared using the same treatments as those
in Example 1, until the high pressure calendering
treatment, except that KI gel 201K-F4Q
(isobutylene-maleic anhydride crosslinked copolymer in
which particles having a diameter between 45 ~m and
425 ~m of 13.7% and particles having a diameter under
45 ~m of 86.3% by weight are included) supplied from
- 25 - 2~80131
Kurare Kabushiki Kaisha is used in place of
KI gel 201K-F3. The density of the obtained coating
layer is 0.88 g/cm3. The obtained water shieldable
material is cut to a tape having a width of 2.5 cm and
the water shieldability is measured. The obtained
results are shown in Tables 1 and 2. As shown in
Table 2, the water shieldability according to the
T-letter method is superior, but the water shieldability
according to the L-letter method is inferior. Generation
of a hydrogen gas cannot be found in the putrefaction
test. Micrographs of the water shieldable material in
Comparative Example lb are shown in Fig. 7 (cross
sectional view) and Fig. 4 (plain view).
Example 2
15A water shieldable material of Example 2 is prepared
using the same treatments as those in Example 1 until the
high pressure calendering treatment, except that
KI gel 201K-F4Q (particles having a diameter between
45 ~m and 425 ~m of 90~ by weight or more is included) is
used in place of KI gel 201K-F3. The density of the
~~obtained coating layer is 0.91 g/cm3. The obtained water
shieldable material is cut to a tape having a width of
2.5 cm and the water shieldability is measured. The
obtained results are shown in Tables 1 and 2. As shown
in Table 2, the water shieldability of Example 2 is
superior in both the L-letter method and the T-letter
method. Workability in cable connection and covering
buffer properties of this Example are superior, and the
generation of hydrogen gas cannot be found in the
putrefaction test.
Comparative Example lc
A water shieldable material of Comparative
Example lc is prepared using the same treatment as those
in Example 1, except that the content of TUFDENE 1000 is
changed to 7.5 parts and the content of TUFPRENE A is
changed to 7.5 parts. The density of the obtained
2~0131
~ 26 -
coating layer is 0.70 g/cm3. The water shieldability of
this Comparative Example lc is measured and the obtained
results are shown in Tables l and 2. As shown in
Table 1, the high water absorption polymer particle in
this Comparative Example lc is likely to drop away before
the material is in contact with the water and thus the
water shieldability is inferior. Generation of hydrogen
gas cannot be found in the putrefaction test.
Comparative Example ld
A water shieldable material of Comparative
Example ld is prepared using the same treatments as those
in Example l until the high pressure calendering
treatment, except that KI gel 201K-F2 (isobutylene-maleic
anhydride crosslinked copolymer in which particles having
a diameter between 45 ~m and 425 ~m of 13.7% and
particles having a diameter under 45 ~m of 86.3~ by
weight are included) supplied from Kurare Kabushiki
Kaisha is used in place of KI gel 201K-F3. The density
of the obtained coating layer is 1.11 g/cm3. The
obtained water shieldable material is cut to a tape
having a width of 2.5 cm and the water shieldability is
measured. The obtained results are shown in Tables 1 and
2. As shown in Table 2, the water shieldability
according to the T-letter method is superior, but thç
water shieldability according to the L-letter method is
inferior. Generation of hydrogen gas cannot be found in
the putrefaction test.
Example 3
The following materials are mixed and uniformly
dispersed.
TUFDENE 2100R (stylenebutadiene group rubber)
supplied from Aasahi Kasei Kogyo Kabushiki Kaisha
--- 2.07 parts
SOLPRENE T411 (Stylenebutadiene group rubber)
supplied from Aasahi Kasei Kogyo Kabushiki Kaisha
--- 2.07 parts
- 27 - 2Q~OI31
KI gel 201K-F3 ~isobutylene-maleic anhydride
crosslinked copolymer in which particles having a
diameter between 45 ~m and 425 ~m of 91% by weight
is included)
Supplied from Kurare Kabushiki Kaisha ---9.7 parts
AK510 (sodium dialkylsulfosuccinate group
hydrophilic agent supplied from Marubishi Yuka Kogyo
Sha) --- 0.1 parts
SUMILIZER BP76 (phenol group primary antioxidant
supplied from Sumitomo Chemical Industry Co. Ltd.)
--- 0.05 parts
SUMILIZER TPD (organic sulfur secondary antioxidant
supplied from Sumitomo Chemical Industry Co. Ltd.)
--- 0.05 parts
Toluene (used as a diluent) --- 90 parts
The dispersion liquid is coated on a polyester spun
bond E-5060 in such a manner that the pick-up of the high
water absorption polymer becomes 100 g/m2, and the coated
nonwoven fabric is dried. SMASH YR10 is placed on the
coating layer of the coated sheet, and is then treated
with a high pressure calender having a linear pressure of
70 kg/cm and a temperature of 50C. The density of the
obtained coating layer is 0.78 g/cm3. The obtained water
shieldable material is cut to a water shieldable tape
having a width of 2.5 cm. The water shieldability of the
obtained material is measured and the obtained results
are shown in Tables 1 and 2. As shown in Table 2, the
water shieldability of Example 3 is superior in both the
L-letter method and the T-letter method. Workability in
cable connection and covering buffer properties of the
Example 3 are superior, and the generation of hydrogen
gas cannot be found in the putrefaction test.
Comparative Example 2
A water shieldable tape of Comparative Example 2 is
prepared using the same treatment as that in Example 2,
except that the content of TUFDENE 2100R is changed to
- 28 - 2Q80131
4.85 parts, the content of SOLUPULEN T411 is changed to
4.85 parts, and the content of KI gel 201K-F3 is changed
to 4.14 parts. The density of the obtained coating layer
is 0.76 g/cm . The water shieldability is measured and
the obtained results are shown in Table 1 and 2. As
shown in Table 2, the water shieldability of this
Comparative Example 2 is inferior. Generation of
hydrogen gas cannot be found in the putrefaction test.
Example 4
A water shieldable tape of Example 4 is prepared
using the same treatment as that in Example 1, except
that DIENE 35R (butadiene group rubber, supplied from
Asahi Kasei Kogyo Kabushiki Kaisha) is used in place of
TUFDENE 1000, and TUFTEC H1052 (stylenebutadiene group
rubber supplied from Asahi Kasei Kogyo Kabushiki Kaisha)
is used in place of TUFPRENE A. The density of the
obtained coating layer is 0.77 g/cm3. The water
shieldability is measured, and the obtained results are
shown in Tables 1 and 2.
As shown in Table 2, the water shieldability of
~~~ Example 4 is superior in both the L-letter method and the
T-letter method. Workability in cable connection and
covering buffer properties of this Example are superior,
and generation of hydrogen gas cannot be found in the
putrefaction test.
Comparative Example 3
A water shieldable tape of Comparative Example 3 is
prepared using the same treatment as that in Example 1,
except that CEMEDINE 198L (vinyl acetate group binder,
supplied from Cemedine Sha) is used in place of a
stylenebutadiene rubber, and methanol is used as a
solvent. The density of the obtained coating layer is
0.51 g/cm . The water shieldability is measured, and the
obtained results are shown in Tables 1 and 2. As shown
in Table 2, the tape of Comparative Example 3 is hard to
handle and thus the handling properties of the tape are
2~80131
- 29 -
inferior and the water shieldability is also inferior.
Generation of hydrogen gas cannot be found in the
putrefaction test.
Example 5
A water shieldable tape of Example 5 is prepared by
the same treatment as that in Example 2, except that
Aqualic CS-7R (sulfoalkylacrylate group crosslinked
polymer in which particles having a diameter between
45 ~m and 425 ~m of 65% by weight is included, and
supplied from Nihon Shokubai Sha) is used in place of
KI gel 201K-F3. The density of the obtained coating
layer is 0.82 g/cm3. The water shieldability is
measured, and the obtained results are shown in Table 1
and 2. As shown in Table 2, the water shieldability of
Example 5 is superior in both the L-letter method and the
T-letter method. Generation of hydrogen gas cannot be
found in the putrefaction test.
Example 6
A water shieldable material of Example 6 is prepared
using the same treatment as that in Example 1, except
that KI gel 201K-F4 (isobutylene.maleic anhydride
crosslinked copolymer in which particles having a
diameter between 45 ~m and 425 ~m of 80% by weight and
supplied from Kurare Sha) of 70 parts is used in place of
KI gel 201K-F3. The density of the obtained coating
layer is 0.87 g/cm3. The water shieldability is measured
and the obtained results are shown in Tables l and 2. As
shown in Table 2, the water shieldability of Example 6 is
superior in both the L-letter method and the T-letter
method. Generation of hydrogen gas cannot be found in
the putrefaction test. Micrographs of the water
shieldable material in Example 6 are shown in Fig. 5
(cross sectional view) and Fig. 6 (plain view).
- 30 -
~ o o o o ~ o ~ ~ o ~ 2Q~0131
o ~
a~ . . . . . . .. .
L
.~ a~
v ~ ~ a
~ = = = = = = = s ~
s - s-
~ a h ~ a~
.~, s ~ ~
s
o ~ _
r
o
U o
.~
~ u ~
~S O
11
o
O ~-~1 h
a) h
~ S~
Q ~1 ~ S ~
t~) O !2 1~ ~--Ul
E~
o
Ul ~
:1 a ~ h
~ O
~ h
u: ,1 a
S~
h ~ O ~ t-- ~ ~ ~ ~ o o
~2 ~r
~-~1 3
~ >
O
V
R ~ ~
x x ~ x
a~
h ~ h ~ ~ ~ h ~
X O X O X X O X
,
- 31 - 20~0131
Table 2
Density of Water shieldability Handling
coating property
(g/cm3) L-letter T-letter
method method
(cm) (cm)
Example 1 0.76 408 5 good
Comparative Example la 0.46 303 73 "
" lb 0.88 1000 5 "
Example 2 0.91 430 26 "
Comparative Example lc 0.70 750 140 inferior
~ ld 1.11 1000 or more 8 good
Example 3 0.78 402 5 "
Comparative Example 2 0.761000 or more 77 ~
Example 4 0.77 295 8 "
Comparative Example 3 0.51 650 85 inferior
Example 5 0.82 330 6 good
" 6 0.87 395 6 "
The dropping away ratio of a high water absorption
polymer particle in the water shieldable material of
Example 1, Comparative Examples la, lb and ld, and
Example 6 are measured, and the obtained values are shown
in Table 3 with a weight per unit area (g/m2) of the
corresponding water shieldable materials and a weight
per m2 of the high water absorption polymer before
dropping away thoseof.
- 32 - 20S0131
Table 3
Weight per Weight of Dropping away
unit area polymer ratio (%)
of water particle (purified
shieldable (g/m2) water)
material
(g/m2)
Example 1 213 100 85.1
Comparative Example la 203 100 94.6
" lb 189 88 16.6
" ld 199 88 19.3
Example 6 193 86 84.2
As shown in Table 3, the dropping away ratio of the
water shieldable materials in Examples 1 and 6, and
Comparative Example la are high, but the dropping away
ratio of the water shieldable materials in Comparative
Examples lb and ld are lower. Note that the water
shieldability according to the L-letter method in
Comparative Example la is superior, but the water
shieldability according to the T-letter method is
inferior as described herebefore.
CAPABILITY OF EXPLOITATION IN INDUSTRY
The water shieldable material in accordance with the
present invention is a material having superior water
shieldability in both the L-letter method and the
T-letter method, and is capable of completely satisfying
the characteristics that are required of the water
shieldable material, such as a non-curling property for
various moisture, a stickproofing property, a covering
buffer property, a non-putrefaction property, cable
moldability or the like. Accordingly, the water
shieldable material in accordance with the present
invention can be used as a hold winding tape of an
electrical wire cable and an optical fiber cable.
