Note: Descriptions are shown in the official language in which they were submitted.
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WATER-SWELLABLE ADHESIVE WATER STOP
BACKGROUND OF THE INVENTION
The present invention relates to a novel water-swell-
able adhesive water stop. More particularly, the inventionrelates to a water-swellable adhesive water stop improved
in respect of the workability and capable of exhibiting a
high water-stopping efficiency.
A water stop ls a shaped body widely used to prevent
leakage of water by filling gap spaces, interstices, cracks,
fissures and the like responsible for leakage of water
therethrough, for example, in the joints of precast concrete
bodies, construction joints of mortar or concrete works,
joints in water-supply pipes and the like in civil engineer-
ing works and building construction works in general. Asa trend in recent years, in partlcular, so-called water-
swellable water stops are highlighted in respect of the high
efficiency of water leakage prevention with a capability of
complying wlth any subsequent expansion of the joint gaps
after the construction works by virtue of the volume
increase of the water stop by swelling in water.
The major current in the above mentioned water stops
in the prior art is in the use of those of the complete-
vulcanization type. A problem in the use of the water stops
of this type is in the relatively low working efficiency
therewith due to the requirement of a considerably high
fastening pressure to completely fill up the gaps in a joint
between irregular or rugged surfaces or at a corner portion
of concrete bodies because the water stop material usually
has a high tensile strength Tb and high compressive elastic
resilience. Accordingly, it is eagerly desired to develop
a novel water-swellable water stop material improved in this
regard.
Besides, known water stops include those formulated
with a readily deformable water-resistant material, such as
rubbers, plastics, bitumens and the like, as a base. The
water stops formulated with these base materials, however,
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are not always quite satlsfactory in respect of their poor
compllance with the changes ln the dimensions of the gaps
fllled therewith due to the decrease in the elastic resil-
ience or appearance of the phenomenon of creeping after a
long time of service so as to cause a loss in the leakage-
preventlng power. Water stops of the water-swellable
vulcanized-rubber type have also been proposed although they
still have a problem to be solved in respect of the poor
working efficiency as a consequence of the initial leakage-
preventing effect exhibited largely depending on theadhesive and the compressive elastic resilience of the
rubber.
On the other hand, water stops formulated with an
adheslve butyl rubber are under prevailing use as a water
stop for gap-filling applications despite the defects due
to the relatively large permanent compression set and poor
restorability thereof. Water-swellable adhesive water stops
formulated with a butyl rubber have been proposed as an
improved modification of the above but they, being of the
unvulcanized-rubber type, have a defect in the basic
properties that the water stop is susceptible to collapsing
under the swelling pressure which the water stop cannot
withstand when swollen with water.
SUMMARY OF THE INVENTION
The present invention accordingly has an object to
provide an improved water-swellable adhesive water stop of
excellent performance by fully overcoming the above describ-
ed problems and disadvantages in the conventional water-
swellable water stops, which is imparted simultaneously with
the good workability possessed by the unvulcanized adhesive
butyl rubbers in the prior art and the good leakage
preventing power of the water-swellable water stops of the
vulcanized-rubber type and capable of exhibiting excellent
adhesiveness, relatively small compressive elastic resil-
ience, good workability in gap-filling works and high
leakage-preventing effect under the surface-contacting
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pressure by the rapld swelling with water to fully comply
with separation of the jointed surfaces in the joint after
working along with a sufficiently high materlal strength to
withstand the swelling pressure which might cause collapsing
of the water stop.
Thus, the water-swellable adhesive water stop of the
present invention, which has been completed as a result of
the extensive investigations undertaken by the inventor, is
a shaped and vulcanized body of a composition comprising:
(A) 100 parts by weight of a butyl rubber;
(B) from 1 to 50 parts by weight of a highly water-absorp-
tive resin;
(C) from 30 to 200 parts by weight of an inorganic water-
absorbent, preferably, having basicity;
(D) from 10 to 50 parts by weight of a tackifier;
(E) from 30 to 200 parts by weight of a plasticizer;
(F) from 0.1 to 5 parts by weight of a vulcanizlng agent;
and
(G) optionally, up to 300 parts by weight of a basic filler,
and has a tensile strength Tb in the range from 1 to 30
kgf/cm2, a 100% elastic modulus in the range from 1 to 4
kgf/cm2, ultimate elongation at break Eb of at least 300%
and water-swellability S2l in the range from 150 to 500%
at 23 ~C.
The above mentioned water-swellability S2, or, gener-
ally, S~ is defined by the ratio in % of the weight of the
material swollen by keeping in water at 23 ~C for 21 days
or n days to the weight of the same material before swelling
with water.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
The butyl rubber or isobutylene-based rubber used as
the component (A) in the present invention includes so-
called butyl rubbers as a copolymeric rubber of isobutylene
and a small amount of isoprene, which should preferably
have a degree of unsaturation of 0.3 to 3.0% by moles, and
halogenated butyl rubbers, e.g., chlorinated and brominated
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butyl rubbers, which should preferably have a degree of
unsaturation of 0.1 to 3.0% by moles and a halogen content
of 0.3 to 3.0% by welght. In particular, chlorinated and
bromlnated butyl rubbers are preferred in respect of the
high reactlvity.
The hlghly water-absorptlve resln used as the component
(B) ln the present invention is a polymeric electrolyte
having a crosslinked structure capable of absorbing water
ln an amount of several tens to several hundreds times by
welght based on the welght of the polymer at room tempera-
ture and serves as a swelling-supporting material and
includes, for example, poly(acrylic acid)-based ones,
modified poly(vinyl alcohol)-based ones, copolymers of vinyl
alcohol and acryllc acid, copolymers of an olefin and maleic
anhydrlde and the like. The last mentloned copolymers of
an olefln and malelc anhydrlde, such as a commerclally
avallable product sold under the tradename of KI Gel, are
preferred. The amount of thls component (B) ls usually ln
the range from 1 to 50 parts by weight or, preferably, from
3 to 40 parts by welght per 100 parts by weight of the
component (A)~ When the amount of the com-ponent (B) is
too small, the water stop prepared from the composltlon
would be poor in the water-swellability showing only
insufficient degree of expansion by swelling or taking an
unduly long tlme for swelling resulting in a poor water
leakage-preventing power. When the amount of the component
(B) is too large, on the other hand, the water stop may
exhlblt an excesslvely large swelling pressure eventually
resulting in collapsing of the water stop bodies per se or
cracking of the concrete bodies by the back-pressure of the
back-fills.
The component (C) compounded in the water-swellable
composltion for the water stop is can be any of inorganic
powdery materials capable of swelling by absorbing water
in an amount of several to several tens times by weight
based on the dry weight of the powder at room temperature.
Examples of such an inorganic water-absorbent include, for
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example, sil1cic acid compounds such as hydrated sllicic
acid, hydrated sllicates and the like, bentonites mainly
composed of montmorillonite and so on. The inorganic water-
absorbent as the component ~C) should preferably have
basicity as determined by the pH of at least 8 or, prefer-
ably, at least 9 of a 10% by weight aqueous suspension
thereof. The amount of the component (C) compounded in the
water-swellable composltion is usually in the range from 30
to 200 parts by weight or, preferably, from 50 to 150 parts
by weight per lO0 parts by weight of the component (A).
When the amount of the component (C) is too small, the water
stop prepared from the composition would be poor ln the
water-swellability showing only insufficient degree of
expansion by swelling or taking an unduly long time for
swelling resulting in a poor water leakage-preventing power,
in particular, at the initial stage. When the amount of
the component (C) is too large, on the other hand, the
workability with the water stop would be poor due to the
eventual collapsing or hardening of the water stop bodies
when swollen with water.
The component (D) compounded in the water-swellable
composition for the inventive water stop is a tackifier
which is exemplified by petroleum resins including those
of the aliphatic, aromatic, alicyclic, copolymeric and
hydrogenated types, terpene reslns including polyterpenes,
terpene-phenol resins and the like, xylene resins including
modified xylene resins, phenolic resins including alkylphe-
nol resins, modified phenol resins and the l1ke, coumarone-
indene resins, rosins, rosin-based resins including modified
roslns and the like, shellacs, dammar resins, copal resins,
polybutenes, polyisobutylenes, liquid polychloroprenes,
liquid polybutadienes and the like. The amount of the
component (D) is usually in the range from 10 to 50 parts
by weight or, preferably, from 15 to 40 parts by weight per
lO0 parts by weight of the component (A). When the amount
of the component (D) is too small, the water stop would only
have poor adhesiveness and the impregnability thereof to
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jolnt gaps is decreased. When the amount thereof is too
large, on the other hand, the surface of the water stop is
lmparted with hydrophobicity more or less so that the water
stop is less water-swellable not to fully exhibit the
desired water leakage preventing power.
The component (E) compounded in the water-swellable
composition for the inventive water stop is a plasticizer
which is exempllfied by plasticizers of phthalic acld-
mineral oil of the paraffinic, naphthenic or aromatic type,
phosphate ester-based plasticizers, adipate-based plasti-
cizers, sebacate-based plasticizers, stearic acid, palmitic
acid, castor oil, cottonseed oil, rapeseed oil, paraffins,
chlorinated paraffins and the like. The amount of the
plasticizer as the component (E) compounded in the water-
swellable composition for the inventive water stop isusually in the range from 30 to 200 parts by weight or,
preferably, from 50 to 150 parts by weight per 100 parts by
weight of the component (A). When the amount thereof is too
small, the composltion is imparted with increased hardness
resulting in poor workability of the water stop prepared
therefrom. When the amount thereof is too large, on the
other hand, the composition is imparted with decreased
hardness so that the water stop prepared therefrom would be
under a risk of eventual collapsing by swelling with water
after working.
The component (F) compounded in the water-swellable
composition for the inventive water stop is a vulcanizing
agent which is exemplified by sulfur, modified phenolic
resins such as methylolated alkylphenol resins, brominated
alkylphenol resins and the like and thiuram compounds such
as tetramethyl thiuram disulfide, tetramethyl thiuram
monosulfide and the like. The amount of the component (F)
is usually in the range from 0.1 to 5 parts by weight or,
preferably, from 0.3 to 2.0 parts by weight per 100 parts
by weight of the component (A). When the amount of-the
vulcanizing agent is too small, the crosslinking density in
the water stop would be too low so that the water stop body
21~f 4I 3
has poor mechanlcal strengths resulting in eventual col-
lapsing of the water stop body after swelllng with water.
When the amount of the vulcanizing agent is too large, on
the other hand, an undesirable phenomenon of blooming may
be caused on the surface of the water stop.
It ls usually desirable that the vulcanizing agent as
the component (F) is used in combination with a vulcaniza-
tion accelerator. Examples of the vulcanization accelerator
include thiourea compounds such as mercaptoimidazoline and
the like, thiazole compounds such as mercaptobenzothiazole,
dibenzothiazyl disulfide and the like, carbamate compounds
such as zinc dimethyl dithiocarbamate, copper dimethyl-
dithiocarbamate and the like, and so on. Though largely
dependent on the types of the vulcanizing agent, the amount
of the vulcanization accelerator is usually in the range not
to exceed 5 parts by weight or, preferably, from 0.5 to 3
parts by weight per 100 parts by weight of the component
~A).
Further, the water-swellable composition for the
inventive water stop is compounded optionally with a basic
filler as the component (G), especially, when the inorganic
water-absorbent as the component (C) has no basicity. The
basic filler here implied includes various kinds of inor-
ganic fillers of which a 10% by weight aqueous suspension
has a pH of 8 or higher or, preferably, 9 or higher as
exemplifled by magnesium carbonate hydroxide, calcium
carbonate hydroxide and the like. Compounding of the
component (G) has an effect to accelerate water absorption
and swelling of the water stop when it is contacted with
water so that the initial water-stopping effect can be
rapidly exhibited. The amount of the component (G) usually
should not exceed 300 parts by weight or, preferably, should
not exceed 200 parts by weight per 100 parts by weight of
the component (A). When the amount thereof is too large,
the water leakage preventing power of the water stop may
be somewhat decreased.
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In addltion to the above descrlbed components, lt
is optlonal that the water-swellable composition for the
inventive water stop is admixed with various kinds of
additives conventionally compounded in the prior art water
stops each in a limited amount. Some of such optional
additlves lnclude aging retarders, fillers, coloring agents,
processing aids and the like. Examples of the aging
retarder include amine compounds, phenolic compounds and
the like. Examples of the filler include calcium carbonate,
zlnc oxide, hard clay, carbon black and the like.
The water-swellable adheslve water stop of the inven-
tion can be prepared by uniformly compounding the above
described components each in a specified amount by using a
suitable blending machine such as a pressurizable kneader
and the like to give a water-swellable composition and then
shaping and vulcanizing the shaped composltion to such an
extent that the vulcanlzed compositlon may have a tensile
strength Tb in the range from 1 to 30 kgf/cm2, 100% elastic
modulus in the range from 1 to 4 kgf/cm2, ultimate elonga-
tlon at break Eb of at least 300% and degree of swellingSz, ln the range from 150 to 500%. The definition of the
degree of swelling Sz~ lS given before. The water-swellable
composition can be shaped by any known shaping method
lncludlng extrusion molding, compression molding and the
llke.
The water-swellable adhesive water stop prepared in the
above described manner exhibits excellent performance for
water leakage prevention with various advnatages including
high adhesiveness to the substrate surface, relatively small
compressive elastic resillence, good workability such as
impregnability in working to any narrow gaps, follow-up
behavlor to the gap expansion after working by virtue of
swelling with water and sufficiently high strengths to
withstand the collapsing force caused by excessive swelling.
Accordingly, the water-swellable adhesive water stop
of the invention can be used in a wide field of applications
not only in civil engineering and architectural works of
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construction and maintenance for the prevention of water
leakage through the joints in the shield tunnel works and
shield segments, joints of precast concrete bodies such as
precast concrete pipes, precast culvert boxes and the like,
construction joints in concrete structures, joints between
steel-made bodies such as U-flumes, corrugated pipes and
the like but also as various kinds of repair materials and
water-retainlng material in agriculture and horticulture.
In the following, examples are given to illustrate the
present invention in more detail but not to limit the scope
of the invention in any way. The term of "parts" appearing
in the following always refers to "parts by weight". The
materials used in the following examples for compounding
are specified as follows.
(I) Butyl rubber A: Exxon*Butyl 268, a product by Exxon
Chemical Co.
(II) Butyl rubber B: Exxon Butyl 065, a product by Exxon
Chemical Co.
(III) Butyl rubber C: Exxon Bromobutyl 2244, a product by
Exxon Chemical Co.
(IV) Highly water-absorptive resin: KI Gel, a product by
Kuraray Co.
(V) Inorganic water-absorbent A: Nipsil* VN-3, a product by
Nippon Silica Kogyo Co. (hydrated silicic acid, neutral)
(VI) Inorganic water-absorbent B: Nipsil NA, a product by
Nippon Silica Kogyo Co. (hydrated sllicic acid, basic)
(VII) Tackifier: petroleum resin Escorez 1102, a product
by Tonex Co.
(VIII) Plasticizer: naphthenic process oil
(IX) Vulcanizing agent A: sulfur
(X) Vulcanizing agent B: tetramethyl thiuram disulfide
(IX) Vulcanization accelerator: mercaptobenzothiazole
(XII) Basic filler A: magnesium carbonate hydroxide
(XIII) Basic filler B: calcium carbonate hydroxide
*Trade Mark
~. ~ .v
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Example 1.
A butyl rubber compound was prepared by thoroughly
blendlng, ln a pressurlzable kneader for 30 minutes, 100
parts of the butyl rubber A, 20 parts of the highly water-
absorptive resin, 80 parts of the inorganic water-absorbent
A, 20 parts of the tackifler, 80 parts of the plasticizer,
2 parts of the vulcanizlng agent A, 1 part of the vulcanl-
zatlon accelerator 5 parts of zlnc oxlde, 75 parts of
calclum carbonate and 20 parts of carbon black. The com-
pound was extruslon-molded from a 60 mm-dlameter extruder
machine having a screw rotating at 40 rpm and a die kept
at a temperature of 80 ~C and the shaped compound was
vulcanlzed by heatlng at 170 ~C for 8 minutes.
The thus shaped and vulcanized test bodies had a
tensile strength of 19.0 kgf/cmZ, 100% elastic modulus of
2.5 kgf/cm2, ultlmate elongation at break of 1200% and
degree of swelling S2, of 250%. The test bodies swollen
with water maintained the shape before swelllng without
collapsing.
Example 2.
A butyl rubber compound was prepared in the same manner
as in Example 1 by thoroughly blending 50 parts of the butyl
rubber B, 50 parts of the butyl rubber C, 40 parts of the
highly water-absorptlve resln, 30 parts of the lnorganlc
water-absorbent A, 25 parts of the tacklfier, 75 parts of
the plasticlzer, 1.5 parts of the vulcanizing agent A, 0.8
part of the vulcanizing agent B, 4 parts of zinc oxide, 60
parts of calcium carbonate and 16 parts of carbon black.
The compound was extruslon-molded in the same manner as in
Example l and the shaped compound was vulcanized by heating
at 170 ~C for 10 minutes.
The thus shaped and vulcanized test bodies had a
tensile strength of 18.0 kgf/cm2, 100% elastic modulus of
2.0 kgf/cm2, ultimate elongatlon at break of 1350% and
degree of swelllng S2l of 420%. The test bodles swollen
wlth water malntalned the shape before swelllng without
collapslng .
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Example 3.
A rubber compound was prepared ln the same manner as
in Example 1 by thoroughly blending 100 parts of the butyl
rubber C, 80 parts of an EPDM rubber, 40 parts of the highly
water-absorptive resin, 60 parts of the inorganic water-
absorbent A, 50 parts of the tackifier, 120 parts of the
plasticizer, 2 parts of the vulcanizing agent A, 1 part of
the vulcanizing agent B, 5 parts of zinc oxide, 75 parts
of calcium carbonate and 20 parts of carbon black. The
compound was extrusion-molded in the same manner as in
Example 1 and the shaped compound was vulcanized by heating
at 170 ~C for 5 minutes.
The thus shaped and vulcanized test bodies had a
tenslle strength of 25.0 kgf/cmZ, 100% elastic modulus of
2.2 kgf/cm2, ultimate elongation at break of 950% and degree
of swelling S2, of 170%. The test bodies swollen with water
maintained the shape before swelling without collapsing.
Example 4.
A butyl rubber compound was prepared in the same manner
as ln Example 1 by thoroughly blending 100 parts of the
butyl rubber C, 10 parts of the highly water-absorptive
resin, 120 parts of the inorganlc water-absorbent A, 10
parts of a polybutene as a tackifier, 100 parts of the
plasticizer, 1 part of the vulcanizing agent A, 1 part of
25 the vulcanizing agent B, 3.5 parts of zinc oxide, 52.5 parts
of calcium carbonate and 14 parts of carbon black. The
compound was extrusion-molded in the same manner as in
Example 1 and the shaped compound was vulcanized by heating
at 170 ~C for 10 minutes.
The thus shaped and vulcanized test bodles had a
tenslle strength of 15.0 kgf/cm2, 100% elastic modulus of
1.3 kgf/cm2, ultimate elongation at break of 1410% and
degree of swelling S2~ of 220%. The test bodies swollen
with water maintained the shape before swelling without
collapsing.
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Example 5.
A butyl rubber compound was prepared in the same manner
as ln Example 1 by thoroughly blending 50 parts of the butyl
rubber C, 50 parts of a reclalmed butyl rubber, 20 parts of
the hlghly water-absorptive resin, 90 parts of the inorganic
water-absorbent A, 20 parts of the tackifier, 80 parts of
the plasticizer, 2 parts of the vulcanizing agent A, 1 part
of the vulcanlzing agent B, 4 parts of zinc oxide, 60 parts
of calcium carbonate and 16 parts of carbon black. The
compound was extrusion-molded in the same manner as in
Example 1 and the shaped compound was vulcanized by heating
at 170 ~C for 10 minutes.
The thus shaped and vulcanized test bodies had a
tensile strength of 16.0 kgf/cm2, 100% elastic modulus of
15 1.8 kgf/cm2, ultlmate elongation at break of 1150% and
degree of swelling S2, of 280%. The test bodies swollen
with water maintained the shape before swelling without
collapsing.
Comparative Example 1.
A full-vulcanization type SBR rubber compound was
prepared in the same manner as in Example 1 by thoroughly
blending lO0 parts of an SBR, 7 parts of the plasticizer,
2 parts of the vulcanizing agent A, 3 parts of the vulcani-
zation accelerator, 1 part of stearic acid, 3.5 parts of
25 zinc oxide, 52.5 parts of calcium carbonate and 14 parts
of carbon black. The compound was extrusion-molded in the
same manner as in Example 1 and the shaped compound was
vulcanized by heating at 170 ~C for 10 minutes.
The thus shaped and vulcanized test bodies had a
30 tensile strength of 185 kgf/cm2, 100~ elastic modulus of
15 kgf/cm2, ultimate elongation at break of 650% and degree
of swelling S2, of 100% exhibiting low water-swellability
and poor workability.
Comparative Example 2.
A full-vulcanization type rubber compound was prepared
in the same manner as in Example 1 by thoroughly blending
100 parts of a polychloroprene rubber, 60 parts of the
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hlghly water-absorptive resin, 4 parts of magneslum oxide,
5 parts of zinc oxlde, 7 parts of the plasticizer, 1 part
of the vulcanizing agent B, 1 part of stearic acid and 2
parts of an aging retarder. The compound was extrusion-
molded in the same manner as in Example 1 and the shapedcompound was vulcanized by heating at 170 ~C for 10 minutes.
The thus shaped and vulcanized test bodies had a
tensile strength of 55 kgf/cm2, 100% elastic modulus of 9
kgf/cmZ, ultimate elongation at break of 670% and degree
of swelling S2, of 610%. The water-swollen test bodies
retained the shape before swelling without collapsing but
the workability thereof as a water stop was poor due to the
high rigidity.
Comparative Example 3.
An unvulcanizable adhesive butyl rubber compound was
prepared in the same manner as in Example 1 by thoroughly
blending 100 parts of the butyl rubber A, 10 parts of the
tackifier, 100 parts of a polybutene as an additional
tacklfier, 150 parts of calcium carbonate and 30 parts of
carbon black. The compound was extrusion-molded to give
test samples.
The thus shaped test bodies had a tensile strength of
0.57 kgf/cm2, 100% elastic modulus of 0.5 kgf/cm2, ultimate
elongation at break of 1600% and degree of swelling S2 1 of
100% showing a very small swelling with water not to meet
the requirement for a water stop.
Comparative Example 4.
An unvulcanizable water-swellable adhesive butyl rubber
compound was prepared in the same manner as in Example 1 by
thoroughly blendlng 100 parts of the butyl rubber A, 40
parts of the highly water-absorptive resin, 50 parts of the
inorganic water-absorbent A, 10 parts of the tackifier, 100
parts of a polybutene as an additional tackifier, 100 parts
of calcium carbonate and 20 parts of carbon black. The
compound was extrusion-molded to give test samples.
The thus shaped test bodies had a tensile strength of
0.52 kgf/cm2, 100% elastic modulus of 0.48 kgf/cm2 and
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ultlmate elongation at break of 1550%. The degree of
swelling could not be determined because the test bodles
became collapsed in the course of swelling in water.
Comparative Example 5.
A partial-vulcanization type butyl rubber compound was
prepared in the same manner as in Example 1 by thoroughly
blending lO0 parts of a partlally vulcanlzed butyl rubber
Escolant-lO, 30 parts of the highly water-absorptive resin,
40 parts of the lnorganic water-absorbent A, 10 parts of the
tackifier, 50 parts of a polybutene as an additional tacki-
fier, 120 parts of calcium carbonate and 30 parts of carbon
black. The compound was extrusion-molded to give test
samples.
The thus shaped test bodies had a tensile strength of
15 7.0 kgf/cm2, 100% elastic modulus of 4.4 kgf/cm2 and ulti-
mate elongation at break of 790%. The degree of swelling
could not be determined because the test bodies became
collapsed in the course of swelling in water.
Example 6.
A butyl rubber compound was prepared in the same manner
as in Example 1 by thoroughly blending 100 parts of the
butyl rubber A, 10 parts of the highly water-absorptive
resin, 60 parts of the inorganic water-absorbent B, 20 parts
of the tackifier, 60 parts of the plastlclzer, 2 parts of
the vulcanizlng agent A, 1 part of the vulcanization
accelerator, 5 parts of zinc oxide, 50 parts of calcium
carbonate and 15 parts of carbon black. The compound was
extrusion-molded in the same manner as in Example 1 and the
shaped compound was vulcanized by heating at 170 ~C for 5
minutes.
The thus shaped and vulcanized test bodies had a
tensile strength of 2.53 kgf/cm2, 100% elastic modulus of
1.3 kgf/cm2, ultimate elongation at break of at least 2000%
and degrees of swelling Sl, Sl 4 and S2l of 180%, 275% and
304%, respectively. The test bodies swollen with water
maintained the shape before swelling without collapsing.
21121413
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Example 7.
A butyl rubber compound was prepared in the same manner
as in Example 1 by thoroughly blendlng 50 parts of the butyl
rubber B, 50 parts of the butyl rubber C, 30 parts of the
hlghly water-absorptive resin, 30 parts of the inorganic
water-absorbent A, 30 parts of the inorganic water-absorbent
B, 30 parts of the tackifier, 80 parts of the plasticizer,
2 parts of the vulcanizing agent A, 1 part of the vulcaniz-
ing agent B, 5 parts of zinc oxide, 50 parts of calcium
carbonate and 15 parts of carbon black. The compound was
extrusion-molded in the same manner as in Example 1 and the
shaped compound was vulcanized by heating at 170 ~C for 10
minutes.
The thus shaped and vulcanized test bodies had a
tensile strength of 15.8 kgf/cmZ, 100% elastic modulus of
2.8 kgf/cm2, ultimate elongation at break of 1200% and
degrees of swelling S~, S, 4 and S2l of 220%, 350% and 381%,
respectively. The test bodies swollen with water maintained
the shape before swelllng without collapsing.
Example 8.
A butyl rubber compound was prepared in the same manner
as in Example 1 by thoroughly blending 100 parts of the
butyl rubber C, 25 parts of the highly water-absorptive
resin, 80 parts of the inorganic water-absorbent A, 10 parts
of a polybutene as a tackifier, 100 parts of the plasti-
cizer, 1 part of the vulcanizing agent A, 0.8 part of the
vulcanizing agent B, 50 parts of the basic filler A, 5 parts
of zinc oxide, 15 parts of carbon black and 40 parts of
calclum carbonate. The compound was extrusion-molded ln
the same manner as in Example 1 and the shaped compound was
vulcanized by heating at 170 ~C for 4 minutes.
The thus shaped and vulcanized test bodies had a
tensile strength of 1.10 kgf/cm2, 100% elastic modulus of
1.1 kgf/cm2, ultimate elongation at break of at least 2000%
and degrees of swelling S~, Sl 4 and S2~ of 250%, 390% and
416%, respectively. The test bodies swollen with water
maintained the shape before swelling without collapsing.
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Example 9.
A butyl rubber compound was prepared in the same manner
as in Example 1 by thoroughly blending 30 parts of the butyl
rubber B, 70 parts of the butyl rubber C, 10 parts of the
highly water-absorptive resin, 60 parts of the inorganic
water-absorbent A, 10 parts of a polybutene as a tackifier,
70 parts of the plasticlzer, 2 parts of the vulcanizing
agent A, 1 part of the vulcanizing agent B, 0.8 part of the
vulcanization accelerator, 50 parts of the basic filler B,
5 parts of zinc oxide, 15 parts of carbon black and 40 parts
of calcium carbonate. The compound was extrusion-molded in
the same manner as in Example 1 and the shaped compound was
vulcanized by heating at 170 ~C for 7 minutes.
The thus shaped and vulcanized test bodies had a
tensile strength of 1.80 kgf/cm2, 100% elastic modulus of
1.5 kgf/cm2, ultimate elongation at break of at least 2000%
and degrees of swelling S7, Sl 4 and S2~ of 150%, 230% and
260%, respectively. The test bodies swollen with water
malntained the shape before swelling without collapsing.
Example 10.
A butyl rubber compound was prepared in the same manner
as in Example 1 by thoroughly blending 100 parts of the
butyl rubber A, 60 parts of the inorganic water-absorbent
B, 20 parts of the highly water-absorptive resin, 20 parts
of the tackifier, 60 parts of the plasticizer, 2 parts of
the vulcanizing agent A, 1 part of the vulcanization accele-
rator, 60 parts of the basic filler A, 5 parts of zinc oxide
and 15 parts of carbon black. The compound was extrusion-
molded in the same manner as in Example 1 and the shaped
compound was vulcanlzed by heating at 170 ~C for 5 minutes.
The thus shaped and vulcanized test bodies had a
tensile strength of 1.80 kgf/cm2, ultimate elongation at
break of at least 2000~ and degrees of swelling S7, S~ 4 and
S2 1 of 210%, 330% and 368%, respectively. The test bodies
swollen with water maintained the shape before swelling
without collapslng.
2û214I3
. ..~
- 17 -
Comparative Example 6.
A butyl rubber compound was prepared ln the same manner
as in Example 1 by thoroughly blendlng 50 parts of the butyl
rubber A, 50 parts of the butyl rubber C, 80 parts of the
highly water-absorptlve resin, 10 parts of the tackifier,
80 parts of the plasticlzer, 2 parts of the vulcanizing
agent A, l part of the vulcanlzation accelerator, 10 parts
of zinc oxide, 100 parts of calcium carbonate and 30 parts
of carbon black. The compound was extrusion-molded in the
same manner as in Example 1 and the shaped compound was
vulcanized by heating at 170 ~C for 5 minutes.
The thus shaped and vulcanized test bodies had a
tensile strength of 3.50 kgf/cm2, 100% elastic modulus of
2.6 kgf/cm2, ultimate elongation at break of at least 1800%
and degree of swelling S7 of 320~. The thus prepared water
stop had poor mechanical strengths and was collapsed during
the further continued lmmersion in water.
