Note: Descriptions are shown in the official language in which they were submitted.
This invention relates to chromatic marks for
use in rubber articles provided with an an-tioxidant-
migra~ion fil~ barrier having an excellent flex resist-
ance which hardly cause color failure and have excellent
flex resistance and wea~her resistance.
Heretofore, there have been made various
studies on a technic for adhering a chromatic mark to
rubber articles after vulcaniza-tion, particularly tires.
For instance, there is practically no problem on the
adhesion between the vlllcanized rubber and the mark when
using the technic as disclosed in Japanese Patent Applica~
tion Publication No. 36,910/77. In this case, however,
the stain resistance of the mark is considerably poor, so
that the antioxidant migrates from the vulcanized ru~ber
of the rubber article into the mark in a short period to
cause color failure o~ the mark. Moreover, such a color
failure can be prevented by using a stainproof antioxidant,
but the antioxidative performance of this stainproof
antioxidant is considerably inferior to that of a-n amine-
series antioxidan-t having a strongest staining property,
so that the stainproof antiox:idant cannot generally be
used only for preventing the color fa:ilure of the chromatic
mark.
Now, there have been made many studies in order
to prevent the color failure of the chromatic mark when
using an amine-series antioxi.dant or the like having
a strong staining property to rubber articles. Among
them, a method as disclosed in Japanese Pa-tent laid open
No. 56-13~,006 is excellent in the effect of preventing
the color failure, but it has some drawbacks that small
- 2 -
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scratches are innumcrably formed on the surface of the
mark due to the presence of a metal foil disposed on the
mark, and that when a tire provided with such a mark is
run at a state of insufficient internal pressure for
a long time, the me-tal foil is broken by fatigue to form
a breaking nucleus, from which crack grows up to an outer
rubber layer of -the tire.
It is, therefore, an object of the invention to
provide a chromatic mark for use in rubber articles which
eliminates the aforementioned drawbacks, prevents the
color failure, and considerably improves -the beautiful
appearance, flex resistance and weather resistance~
According to the inven-tion, there is provided
a mark for use in rubber articles comprising a chromatic
rubber composition layer containing not less than
30 parts by weight of at least one of chloroprene rubber
and chlorosulfonated polyethylene rubber per 100 parts by
weight of total rubber content and having a thickness of
0.1 to ].5 mm, an antioxidant-migration film barrier
selected from polyester film, nylon film, vinylidene
chloride film and vinylidene chloride-vinyl chloride
copolymer film and having a thickness of 3 to 100 ~Im, and
an adhesive layer selected from thermoplastic polyes-ters
and thermoplastic polyurethanes and having a thickness of
0.005 to 0.5 mm.
In the preferred embodiment of the invention,
the mark has a three-layer structure obtained by laminating
the chromatic rubber composition layer, the antioxidant-
migration film barrier and the adhesive layer in this
order, or a four-layer structure obtained by laminating
the chromatic rubber composition layer, the adhesive
layer, the antioxiclant-migration film barrier and the
adhesive layer in this order, or a six-layer structure
obtained by laminating the chromatic rubber composition
layer, the adhesive layer, the antioxidan-t-migration film
barrier~ a shock-absorbing rubber composition layer
containing not less than 30 parts by weight of at least
one of chloroprene rubber and chlorosulfonated poly-
ethylene rubber per 100 parts by weight of total rubber
content and having a ~hickness of 0.1 to 1.5 mm, and ~he
adhesive layer in this order.
In another preferred embodiment of the invention,
the mark for use in rubber articles is compose~ of a
~our-layer laminate obtained by laminating a chromatic
rubber composition layer containing not less than 50 parts
by weight of chlorosulfonated polyethylene rubber with
a chlorine content of not less than 30% by weigh-t per
100 parts by weight of total rubber content and having
a thickness of 0.1 to 1~0 ~m, a ny:Lon copolymer film
barrier having a thickness of 0.008 to 0.3 mtrl and
a softening point of 100 to 180C~ a shock-absorbing
rubber composition layer containing not less than 50 parts
by weight of chlorosulona-ted polyethylene rubber with
a chlorine content of not less than 30% by weight per --
100 parts by weight of total rubber content and having
a thickness of 0.1 to 1.5 mm, and an aclhesive layer of
thermoplastic polyester or thermoplastic polyurethane
having a thickness of 0.OOS to 0.2 mm and a softening
point of ~0 to 200C in this order, and has a total
thickness of Q.25 to 3.0 mm.
7~
According to the invention, it is favorable in
practice that the outer surface of the mark is pro-tected
by providing a protective coating on the surface o~ the
chromatic rubber composition layer. Further, it is
preferable ~o form an indicative print on the surface of
the chroma~ic rubber composition layer from viewpoints of
expressiveness, beautiful appearance and labor-saving.
Moreover, the term "chromatic" color -used
herein means to be a color having either a lightness
or a saturation or both. If the chromatic color has the
lightness as in white, gray or the like, it has not
necessarily the saturation. And also, if -the chromatic
color is black and has a brightness or the like and is
different from black color of the tire in the color tone,
it may be used as a mark.
The invention will be described in greater
de tail below.
In the chromatic rubber composition layer and
the shock-absorbing rubber composition layer according to
the invention, chloroprene rubber and chlorosulfonated
polyethylene rwbber are used as a rubber component because
they have a considerably e~cellent weather resistance,
~mong them, the use of chlorosulfonated polyethylene
rubber is more preferable because it is excellent in the
adhesion to polyester film, nylon copolymer film, thermo-
plastic polyester and thermoplastic polyurethane.
The chloroprene rubber is preferable -to have
a grade that the crystallization is slow and the change
of hardness at low temperature is small. The chloro-
3~ sulfonated polyethylene rubber is preferable to have
7~
a chlorine content o-f ~5 to 43% by weight, preferably 30
to 43/0 by weight. When the chlorine conten-t is less than
25% by weight~ the adhesion to adjoining layers lowers.
In the rubber compositions, at least one of
chloroprene rubber and chlorosulfonated polyethylene
rubber is compounded in an amount of not less than
30 parts by weight, preferably not less than 50 parts by
weight per 100 parts by weight of total rubber content,
to which may be aclded at least one diene rubber selected
from acryloni-trile-butadiene copolymer rwbber, synthetic
polyisoprene rubber, natural rubber, polybutadiene rubber,
butadiene-styrene copolymer rubber, butyl rubber,
halogenate~ butyl rubber and the like in such an amount
that the effect o chloroprene rubber cr chlorosulfonated
polyethylene rubber is not damaged.
The chromatic rubber composition layer and the
shock-absorbing rubber composition layer are Eavorable -to
have a hardness (measured at 30~C by a spring hardness
test (A-type~ according to JIS K-6301) of not more than
70 in order to improve the flex resisLance.
These rubber composi-tions may contain a filler
for chromatic color such as silicic anhydride, calcium
carbonate, magnesium carbonate, talc, iron oxide,
bentonite., zinc white, diatomaceous earth, china clay,
clay alumina, titanium oxide and ~he like, or may contain
additives usually used in rubber industry such as
vulcanizing agent, vulcanization accelera-tor~ an-tioxidant~
softener, wax and the like. Furthermore~ they may contain
carbon black, if necessary.
In the chlorosulfonated polyethylene rubber
- 6
i7~
composition, a combination of magnesium oxide ~magnesia~
usually used as a pigment~ thiuram-series vulcanization
accelerator and sulfur or a combination of magnesium
oxide (magnesia), pentaerythritol, thiuram-series
vulcanization accelerator and sulfur is preferably used
as a vulcanizing system. In this case, litharge may be
used as a metal oxide.
As the thiuram-series vulcanization accelerator,
use may be made of accelerator DPTI (dipentamethylene-
thiuram tetrasulfide), accelerator TMTD (tetrame~hylthiuram
disulfide) and the like.
The shock-absorbing rubber composition layer
serves to surface the chromatic rubber composition layer
for the improvement of beautiful appearance and to mitigate
strain if the rubber article is repeatedly subjected to
such a strain. Therefore~ the shock-absorbing rubber
composition layer may have the same composition as in the
chromatic rubber composition layer if the hardness of the
former layer is low, but is most preferable to be macle
darlc, particularly black Erom viewpoint o the surfacing
of the chromatic rubber composition layer.
The antioxidant-migration film barrier to be
used in the invention acts ~o advan-tageously intercept
the migration of the staining amine-series antioxidant
from the rubber article and is selected from polyester
film, nylon film, vinylidene chloride film and vinylidene
chloride-vinyl chloride copolymer film.
As the polyes-ter film are used films produced
by using a polyester or a blend of two or more polyester
as mentioned below. As the polyester, mention may be
7~
made of polybisphenol A terephthalate, polyethylene
terephthalate, polybu~ylene terephthalate, poly-~1,4,7-
trioxa-3,3,5,5-tetrafl-uoroheptamethylenecarbonyl-1,3~
phenylenehexafluorotrimethylene-1,3-phenylenecarbonyl),
poly-(1,4,7-trioxa-3,3,5,5-tetrafluoroheptamethyleneiso-
phthaloyl), poly-(1,4,7-trioxa-3,3,595-tetrafluorohepta-
methylene-5-pentyloxyisophthaloyl), poly-(oxyadipoyloxy-
2,6-dichloro-1,4-phenyleneisopropylidene-3,5-dichloro~
phenylene), poly-(oxyadipoyloxy-3,3',5,5'-tetramechyl-4,4-
biphenylene), poly-(oxyadipoyloxydecamethylene), poly-
(oxyadipoyloxy-2,6 dimethyl-1,4-phenyleneisopropylidene-
3,5-dimethyl-1,4-phenylene), poly-(oxyadi.poyloxy~
phenyleneisopropylidene l,4-phenylene), poly-(oxyadi-
poyloxy-2,6-diphenyl-1,4-phenylenemethylene-3,5-diphenyl-
1,4-phenylene), poly-(oxy-5-butyl-1,3-phenyleneoxyiso-
phthaloyl), poly-(oxydibutyltinoxyadipoyl), poly-(oxydi-
butyltinoxyfumaroyl), poly-(oxydibutyltinoxyterephthaloyl),
poly-(oxycarbonyl-3,3'-biphenylene-carbonyl.oxy-1,4-
phenyleneisopropylidene-1,4-phenylene), poly-(oxycarbonyl-
:I,4-~yclohexylenecarbonyloxy-1,4-phenyleneisopropylidene-
1,4-phenylene), poly-(oxycarbonyl-2,6-naph-thylenecarbonyl-
oxydecamethylene), poly-(oxyethyleneoxycarbonyl-1,4-cyclo-
hexylenecarbonyl), poly-(oxyethyleneoxycarbonyl-2,2'-
dimethyl-4,4'-~iphenylenecarbonyl)~ poly-(oxyethyl.eneoxy-
carbonyl-1,1,3-trimethylindan-3,5-irene-1,4-phenylene-
carbonyl), poly (oxyethyleneoxycarbonyl~1,4-naphthylene-
carbonyl), poly-(oxyethyleneoxycarbonyl-1~5-naphthylene-
carbonyl), poly-(oxyethyleneoxycarbony~i-2,6-naphthylene-
carbonyl~, poly-(oxyethyleneoxycarbonyl-2,7-naphthylene-
carbonyl), pol.y-(oxyethyleneoxycarbonyl-1,4-phenylene-
9~iL
sec-butylidene-l 7 4-phenylenecarbonyl), poly-(oxyethylene-
- oxycarbonyl-1,4-naphthylenecarbonyl), poly(oxyethylene-
oxycarbonyl-1,5-naphthylenecarbonyl), poly-(oxyethylene-
oxycarbonyl-2,6-naphthylenecarbonyl), poly-(oxyethylene-
oxyisophthaloyl), poly-(oxy-5-ethyl-1~3-phenyleneoxyiso-
phthaloyl), poly-~oxyisophthaloyloxy-2-methyl-1,4-
phenyleneisopropylidene-3-methyl-1,4-phenylene), poly-
(oxy-2,2,~,4-tetramethyl~1,3-cyclobutyleneoxycarbonyl-
trans-1,4-cyclohexylenecarbonyl~, poly-(oxy-5-methyl-
1,3-phenyleneoxyisoph-thaloyl), poly-~oxyterephthaloyloxy-
methylene-1,4-cyclohexylenemethylene), poly-(oxytere-
phthaloyloxy-1,4-phenyleneisopropylidene-1,4-phenylene)
and the like.
Among these polyester films~ -the use of poly-
ethylene terephthalate is most preferable in view of the
balance between the film strength and the effect of
intercepting antioxidant migra-tion.
As the nylon film, use may be made of nylon-6
film, nylon-6,6 film, nylon~ Eilm, nylon-12 film, ny:lon
copolymer film and the like.
The nylon copolymer :Eilm is obt.ained by
polymerizing two or more nylon homopolymers, and basical]y
by co-condensation polymerization of caprolactam with at
least one other nylon salt. As the other nylon salt are
used nylon-6,6 salt, nylon-6,10 salt and the like.
The nylon copolymer film is preferably used as the
antioxidant-migration film barrier because i-t is high in
the flexibility due to the drop of crystallizability and
good in the adhesion to the chromatic rubber composition
3Q layer and the shock-absorbing rubber com-position layer.
According ~o the invention, the -thermoplastic
polyure~hane or thermoplas~ic polyester is laminated on
either side of ~he antioxidan~-migration film barrier to
form an aflhesive layer for r-ubber article or rubber
composition layer, which serves not only for the bonding
between the chromatic rubber c~mposition layer and the
antioxidant-migration film barrier and the bonding between
the mark and the rubber article, but also to mitigate
permanent strain applied to the antioxidant~migration
film barrier. In the lat~er case9 when the rubber article
is subjected to repetitive strain, residual strain
(or permanent strain) remains only in the antioxidant-
migration film barrier of the mark bonded to the rubber
article because this barrier has no rubbery elasticity
and as a result, i-f compression strain is applied to both
ends of the mark, small wrinkles are produced in the
barrier, so that it is necessary to use ~he thermoplastic
polyurethane or thermoplastic polyester having a flexible
rubbery elasticity capable of sufficiently following ~o
the occurrence of wrinkles.
Therefore, the thermoplastic polyurethane or
polyester is preferable to have a hardness at 30C within
a range of 60 to 96. Furthermore, -the thermoplastic
polyurethane or polyes~er is preferabl~ to have a softening
point of 80C to 200C. When the softening point is less
than 80C, it is apt to cause the peeling at boundary
between the rubber article and the mark if ~he tempera-t-ure
of the rubber article rises to 70-80C For instance,
when the rubber article is a tire, it is possible that
the temperature of the adhesive joint reaches to 60-70C
' 10 -
during the rwnning of -the tire exposed to light in summer
season, so that there is a fear of producing the peeling
of the mark from the tire. On the other hand, when the
softening point exceeds 200~C, the hardness may become
too high. Furthermore, the temperature of 200C is
an upper limit for readily performing the sticking of the
mark in general homes, above which the surface of -the
rubber article is deterioratecl.
According to the invention, the thermoplastic
polyester having the aforementioned softening point range
is a single polyester or a blend of polyesters. In the
thermoplastic polyester blend, the control of the
softening point can be performed by properly selecting
the blend ratio of polyesters, for exalTlple 9 the blend
ratio of polyethylene terephthalate, polybutylene
terephthalate and polyethylene isophthalate. Particularly,
when using a polyester having a low softening point, -the
control of ~he softening point is perEormed by adding
thereto a liquid polyester (trade name: Sansosizer P-1500A,
made by Shinnippon Rika K.K.).
In the thermoplastic polyurethane, the softening
point is usually controlled by changing the molecular
weight of the polyurethane. Moreover, the control of the
softening point may be performed by changing the branching
degree of the molecular chain or by properly blending few
kinds of polyure-thanes.
Alternatively, the softening point and hardness
of the thermoplastic polyester or polyurethane may be
controlled by the addition of a plasticizer~ a filler and
the like.
In the mark according to the invention,
an adhesive may be used between the adjoining layers such
as chromatic rubber composition layer, antioxidant-
migration film barrier, adhesive layer of thermoplastic
polyurethane or polyester and the like. For instance,
when a combination of phenol resin and nitrile ru'bber or
a combination of phenol resin and neoprene is ~sed as the
adhesive between the polyester film and the thermoplastic
polyester layer, the bonding power is considerably
increased.
The invention will be described in detail with
reference to the accompanying drawings, wherein:
Fig. l is a partially perspective view of
an embodiment of the tire provided with t'he mark according
to the invention;
Fig. 2 is a perspective view of an embodiment
of the mark according to the invention;
Figs. 3 to 6 are sectional views of various
embodiments of the mark according to the invention,
respectively; and
Figs. 7 and 8 are sectional views of embodiments
of the mark according to the prior art, respectively.
In Fig. 1 is`shown an embodiment of applying
a mark 1 as shown, for example, in Fig. 2 to a sidewall
of a tire. Such a mark l has a laminate structure of 3
to 6 layers as shown in Figs. 3 to 6. E'or instance, the
mark l of Fig. 3 has a four-layer structure o'btained by
laminating a chromatic rubber composition layer 2,
an adhesive layer 3 of thermoplastic polyurethane or
thermoplastic polyester, an antioxidant-migration film
- 12 -
barrier 4 and an adhesive layer 6 in this order viewed
from the outer surface of the mark, while the mark 1 of
Fig. 4 has a six-layer structure obtained by laminating
a chromatic rubber composition layer 2, an adhesive layer
3, an antioxidant-migration film barrier 4, an adhesive
layer 3t, a shock-absorbing rwbber composition layer 5
and an adhesive layer 6 in this order.
According to the invention, the mark 1 is
bonded to the surace of the rubber article 7 by heating
under pressure through the adhesive layer 6 of thermo-
plastic polyurethane or polyester. In this case, the
bonding between the mark and the rubber article i5
perfonned at a temperature above 100C under pressure by
a proper heating means such as heat press, radiation,
laser, infrared ray or the like.
In the mark according to the invention, the
reason why the thickness of each layer constituting the
mark and the total thickness of these layers are limited
to the ranges as previously mentioned is as fol]ows.
The chromatic rubber composition layer 2 has
a thickness of 0.1 to 1.0 mm. When the thickness is less
than 0.1 mm, the handling is possible in laboratory but
very difficult in industry. While, when the thickness
exceeds 1.0 mm, not only the production cost becomes
vainly higher, but also the total thickness of the mark
becomes excessive, so that it is not favorable in view of
industrialization and beau~iful appearance.
As the antioxidan-t-migration film barrier 4 is
used the film having a high modulus of elasticity as
previously mentioned. Thereforeg when using the film
- 13 -
having a thickness of more -than 100 ~m, if the rubber
article provided with the mark is s-ubjected to repetitive
strain, cracks occur in the boundary between the mark and
the rubber article and grow therefrom. On the other
hand, when the thickness is less than 3 ~m, the film
strength becomes ~oo low and there is a high risk of
producing the breaking of the film during the manufacture
of the mark. For -this reason, the thickness of the
antioxidant migration film barrier should be within
a range of 3 to 100 ~m. Preferably, the thickness of
this barrier is 3 to 15 ~m in view of the flex resistance
of the mark.
The thickness of the adhesive layer 3, 3', 6
composed of thermoplastic polyester or polyurethane is
0.005 to 0.5 mm, preferably 0.005 to 0.2 mrn) more
particularly 0.01 to 0.03 mm. When the thickness is less
than 0.005 mm, satisfactory bonding power cannot be
obtained, while when the thickness exceecls 0.5 mm, extra
amount of the thermoplastic polyester or poly~lrethane
2~ sticks out of the mark during the heat bonding, resulting
in the dama~e of the beautiful appearance.
The shock-absorbing rubber composition layer 5
has a thickness of 0.1 to 1.5 mm. I~hen the thickness is
less than 0.1 mm~ the two func-tions as men-tioned above
cannot be achieved, while when the thickness exceeds
1.5 ~m, strain-mitigating effect is sufficiently satisfied,
but the thickness itself becomes excessiveS resulting in
~.he damage of the beautiful appearance and the increase
of the production cost.
The mark according to the invention has a total
- 14 -
~1~85~
thickness of 0.25 ~o 3.0 mm. When the total thickness is
less than 0.25 mm, the mark is deficient in the three-
dimensional appearance, while when the total thickness
exceeds 3.0 mm, not only the production cost becomes
vainly higher, but also the mark is liable to suffer
external damages in view of the beautiful appearance.
For instance, when the mark is applied to the tire, the
total thickness is most preferable to be about 0.4 to
1.2 mm.
As the another embodiments of the invention~
the mark of Fig. 5 has a three-layer structure obtained
by laminating a chromatic rubber composition layer 2, an
antioxidant-migration film barrier 4 and an adhesive
layer 6 in this order viewed -from -the outer su~face of
the mark, while the mark of Fig. 6 has a four-layer
structure obtained by laminating a chromatic rubber
composition layer 2, an antioxidant-migration film barrier
4, a shock-absorbing rubber composition layer 5 and
an adhesive layer 6 in this order.
In case of applying no adhesive layer to either
side of the antioxidant~migration film barrier 4 as shown
in Fig. 6, nylon copolymer film is preferably use~ as the
barrier 4 because the nylon copolymer film is an antioxidant-
migration barrier having high flexibility and crack
propagation resistance. ~hen usi~g the nylon copolymer
film, the thickness of the barrier should be within
a range of 0.003 to 0.3 mm. When the thickness is less
than 0.003 ~m, the migration of the antioxidant cannot
sufficiently be intercepted~ while when the thickness
exceeds 0.3 mm, the tensile force of the film itself
- 15 -
&~
becomes too large and the stress concentration is
increased when the rubber article is subjected to
repetiti.ve strain and consequently there is cawsed the
peeling between the nylon copolymer film barrier 4 and
the shock-absorbing rubher composition layer 5. Moreover,
the thickness of the nyl.on copolymer film is preferable
within a range of 0.008 to 0.3 ~ because when the
th;.ckness is less than 0.008 mm, the nylon copolymer film
is apt to stick to rol].s or -the like and becomes bad in
the workability.
The lamination of the chromatic r-ubber composi-
ti.on layer 2, nylon copolymer film barrier 4 and the
shock-absorbing rubber composit~on layer S may easily be
performed, for example, by press cwring or the like, and
also the lamination of the shock-absorbing rubber composi-
tion layer 5 to the adhesive layer 6 may easily be
performed by roll press or the like. Moreover, the
lamination of these layers can be carried out by many
well-known methods in addition to the above lami.nation
method.
As apparent from the above, the marks for use
in rubber articles according to the invention have another
significant merit that the industrial production thereof
can be performed in the absence of a solvent. ~ecause,
when a solvent type adhesive is applied to the surface of
each of the layers constituting -the mark~ it is very
difficult ~o obtain a laminate having a uniform thickness
due to the swelling o:E the layer with solvent.
The mark 1 according to the invention may be
bonded to the rubber article 7 as follows: tha-t is,
- 16 -
a surface portion of the rubber artlcle 7 to be bonded
with the mark 1 is first treated with a surface-treating
liquid such as a solution of N,N'-dichlorosulfonamide
compound in acetone or ~he like and then the adhesive
layer 6 of the mark 1 is contacted with the treated
surface portion of the rubber article 7 and heat-pressed
thereto by means of a hot iron. The temperature of the
iron is usually within a range of 150 to 200C, but it is
not intended as limitation thereof.
According to the invention, the hardness is
measured by a spring hardness test (A-type) according to
JIS K-6301, and the softening point of nylon copolymer,
thermoplastic polyurethane or thermoplastic polyester is
measured by a Vicat softening temperature -test according
to JIS K-7~06 under the following conditions:
Measuring device : thermomechanical
analyzer
~TMA-TMS-l~ UU-l),
made by Perkin Elmer
Corp.
Temperature rising ra-te : 0.62C/min
Sample form : cubic body of
5 mm side
Indenter : column with a sectional
area of 1.000~0.015 mm~
(contact surface of
column top is flat)
Load : It is adjustecl to apply
a pressure of 20 g/~n2
to the inden-ter top.
In the latter case, the softening temperature is defined
by a temperature when the indenter is entered into the
sample by 1 ~n.
The following examples are given in illustration
of the invention and are not intended as limitations
- 17 -
9;7~
there~f.
In these examples, properties on the marlc were
evaluated by the following test methods.
1~ Drum test for crack propagation resistance
The tire provided with the mark and
subjected to an internal pressure oE 1.7 kg/cm2 was
run on a drum at a speed of 60 km/hr under JIS 130%
load over a clistance of 20,000 km. Thereafter, the
presence of cracks was observed at the mark and the
boundary between the mark and the tire.
2~ Stainproof test
The tire provided with the mark was left
to stand in a ventilatable oven at ~0C for one week
and then exposed to a ultraviolet ray with a xenon
lamp of 500 W output. Thereafter, the presence of
color failure of the mark was observed.
3) Durability test
The tire (tire size: 165 SR 13) provided
with 10 marks per tire was mounted to a passenge-r
car with a displacement of 1~500 CC9 which was run
over a distance of 41,330 km. Thereafter, the
presence of mark peeling was observed. The property
was evaluated by the number of tires exhibiting the
partial or whole mark peeling.
4~ Drum test under low internal pressure
The tire provided with 10 marks per tire
and subjected to an internal press-wre of 1.2 kg/cm2
wa~ run on a drum a-t a speed of 60 km/hr under JIS
100% load over a distance of 20,000 km. Thereafter,
the presence of cracking of mark and cracking at -the
- 18 -
boundary between the mar'k and the tire sidewall was
observed.
Examples 1 to 10, Prior Art 1 to 2
At first, there were prepared five rubber
compositions having a compounding recipe (unit: par-t by
weight) as shown in the following Table l. The white
rubber compositions of Rubber Composition Nos. 1 and 2
were used in a chromatic rubber composi~ion layer, while
the carbon black-containing rubber compositions of Kubber
Composition Nos. 3 to 5 were used in a shock-absorbing
rubber composition layer.
The materials and trade names of the antioxidant-
migration film layer and adhesive layer to be used were
shown in the following Table 2.
lS Then, twelve marks as shown in the following
Table 3 were manufac-twred by using the materials of
Tables l and 2.
In Examples l to 4, the laminate sheet for the
mar'k was o'btained by bonding the adhesive layer having
a predetermined thick~ess to the rubber composition sheet
press-cured into a predetermined thickness at 155C for
30 minutes and the antioxiclant-migration film 'barrier
having a predetermined thickness wi-th hot rolls.
'Ln Examples 5 and 6 9 the laminate sheet for the
mark was obtained by adhering the antioxidan~-migration
film barrier to the uncured white rubber composition,
press-curing it into a predetermined thickness at 155C
for 30 minutes, and bonding the adhesive layer thereto
with hot rolls.
Ln Examples 7 to 10, the laminate sheet for the
- 19 -
3~ ~
mark was obtained by adhering the antioxidant-migration
film barrier and uncured shock-absorbing ru~ber composition
to the uncured white rubber composition, press-curing it
into a predetermined thi.ckness at 155C for 30 mi.nutes,
and bonding the adhesive layer thereto with hot rolls.
In the prior art 13 the laminate sheet for the
mark was obtained by bonding the thermoplastic polyurethane
having a thickness of 20 ~m to the white ru~ber composition
sheet press-cured into a thickness of 0.7 ~m at 155~C for
30 minutes with ho-t rolls.
In the prior art 2, the laminate sheet for the
mark was obtained by adhering aluminum foil to the uncurecl
shock-absorbing rubber composition, press-curing it at
155C for 30 minutes and bonding the thermoplastic poly-
urethane having a thickness of 20 ~m thereto with hot
rolls.
Then, marks were manufactured by stamping out
circle bodies of 30 mm diameter from each of these
laminate sheets with a knife.
The thus obtained marks were heat-bondecl to
a sidewall of a radial tire for passenger car in an amount
of 10 marks per tire by means of an iron heated at 160C.
In this case, the sidewall of the radial tire for passenger
car (tire size: 165 S~ 13) was previously treated with
a surface-treating liquid consisting of a solution of
N,N'-dichlorobenzene sulfonamide in acetone as disclosed
in Japanese Patent Application Publication No. 36,910/77
prior to the heat bonding of the mark.
The drum test for crack propagation resistance,
stainproof test, durability test and drum test under low
- 20 -
3 ~ 7~
internal pressure as previously mentioned were made with
respect to each of twelve tires provided wi-th ~he mark to
obtain results as shown in Table 3.
- 21 -
7~
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- 25 -
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- 26 -
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27
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- 2~ -
g~
In the marks, particularly chromatic mark
according to the invent;.on, the migration of antioxidant
from rubber article is substantially completely prevented
by using polyester film, nylon ~ilm~ vinylidene chloride
film or vinylidene chloride-vinyl chloride copolymer film
which considerably advantageously prevents the migration
of staining antioxidant, particularly a~ine-series
antioxidant. Furthermore, this film has a swfEicient
performance of preventing the migrati.on of antioxi.dant
even when the thickness is fairly thin, so that the
thickness and rigidity of the mark as a whole can be
reduced. As a result, not only the beautiful appearance
but also the flex resistance, resistance to external
damage and resistance to peeling from rubber article are
considerably improved, and also the weather resistance is
excellent.
Furthermore, according to the invention, the
chromatic rubber composition layer (2), anti.oxidant-
migration film barrier (4), shock-absorbing -rubber
compos.ition layer (5) and adhesive layer (3, 3', 6), each
of w:hich having excellent functional proper~ies, are
properly combined into a laminate structwre of 3 to 6
layers, whereby the flex resistance and weather resis-tance,
which have never been improved in the prior art, are
considerably advantageously improved in addition to the
improvement of beautiful appearance and the prevention o:E
color failure, and also the bonding treatment can simply
be performed.
The marks according to the invention are
preferable as decoration for tires, particularly radial
- 29 -
7~
tires for passenger cars, but may be widely applied ~o
rubber articles requiring a flex resistance, such as
large hoses, conveyor belts, belts for power transmission,
oil fences and the like.
s
- 30 -
