Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
~ t3~
PNEUMATIC TIRE WITH GREY COLORED SID~WA~L
FieId
This invention relates to a tire with a sidewall
with at lea~t a portion thereof having a color
contrasting with the color of the tire. The in~rention
particularly relate~ to a tire with a grey colcred
~idewall component.
Backgxound
Pneumatic rubber tire~ containing carbon black
reinforcement are often prepared with a portion of at
lea3t one sidewall having a color which contrasts to
the color of the remainder of the tire. While various
color~ might be considered, u~ually the contrasting
color is white.
In particular, such a pneumatic rubber tire i~
often prepared with a white sidewall which i~ usually
a black 3idewall having, as a component thereof, an
annular white rubber band or white colored raised
letters embedded~therein.
For ~he white ~idewall, or raised white letters
or other identification, the rubber i3 t~pically
compounded with a white-colored pigment such as, for
example, titanium dioxide. Carbon black is not
normally used in the white sidewal~ because e~en very
~mall amount would di~color the white sidewall
rubber.
It is appreciated that the titanium dioxide
coloring pigment i~ not considered to be a rubber
rein~orcing ingredient for rubber but i8 more in a
form of a filler.
In contrast, the typically unwanted carbon bIack
is well recognized as being a reinforciny ingredient
for rubber, and not simply just a filler pigment or
material.
Disclosure and Practice of the Invention
In accordance with this in~ention, a pneumatic
rubber tire is provided which i9 comprised of a tread,
two ~paced beads, and two sidewall element~ extending
between said tread and bead elements, and a fabric
reinforced carcass supporting 3aid tread and 3idewall,
wherein ~aid txead and 3idewalls are composed of
carbon black reinforced rubber, an improvement
characterized in that at lea~t one of said ~idewalls
containing at least one integral, visible grey colored
rubber component, wherein said rubber component i9 a
sulfur cured rubber containing as ba~ic colorants,
based on 100 part~ by weight rubber, about 1 to about
3 parts by weight carbon black pigment about 4 to
abou~ ~ parts by weight titanium dioxide, where the
weight ratio of carbon black to titanium dioxide i9 in
a range o~ about 1:8 to about 3:4.
The carbon black reinforced rubber sidewall i5
considered to be black in color.
Such colorant~ are referred to as basic colorants
since it considered that the color of the sidewall
band i9 derived primarily from such colorant~ and,
thus, dominate its visible color, although it i8
recognized that it i9 likely that the rubber itself
and other compounding ingredients contained in the
rubber may contribute to its color in a minor way.
In one a~pect, the 3aid grey colored component i3
an annular rubber band.
In another a~pect, the said grey colored-
component i9 compo~ed of raised identifyingcharacters, where said character~ may consist of
Ietter, numbers and/or insignia.
It i~ to be apprecia~e that the color of the
aforesaid cured grey rubber component contained in the
~idewall portion of the tire, absent the titanium
dioxide, would typically be black.
- 3 -
By inclusion of titanium dioxide, a grey-colored
~idewall band i9 provided which has a pleasing effect.
It is also perceived that the basic carbon black
contributes reinforcement to the grey sidewall rubber
which would not be present in a white 3idewall rubber
containing titanium dioxide in the absence o~ carbon
black.
The pre~ence of carbon black i.3 considered of
interest because of the rubber reinforcement quality
of carbon black, and such reinforcement effect would
be considered~to be important since, significantly, a
grPy color i~ imparted to the sidewall rubber a~ being
of good stability because of the resistance of the
carbon black to migrate within the cured rubber
composition.
This is considered to be a particularly
significant ~uality of the carbon black as a colorant.
It is, thu~, considered significant that the grey
color is apparently primarily obtained with pigment3
instead o~ oil-ba3ed dyes, becau~e the dyes would be
expected to migrate to the rubber surface and diminish
their colorant effect over time. Therefore, it i~
anticipated that the utilization of the reinforcement
type of carbon black adds a degree of stability to the
colorant effect for the sulfur cured sidewall rubber.
Contemplated benefits of the carbon black
reinforcement and titanium dioxide reduction for a
grey colored rubber (e.g. grey colored tire sidewall)
which would otherwise be a white colored rubber with
increa~ed titanium dioxide and no carbon black are
reduced weight because of a lower specific gravity
which i~ considered to be an advantage for cost and
rolling resistance due to its somewhat lighter weight;
a durability improvemen~ in tear 3eparation resistance
a~ would be expected to be evidenced by reductions in
curb scuffing and impact separation~.
- 4 -
The aforesaid expected durability improvement is
considered to be due primarily to the carbon black
reinforcement a~pect of the grey colored rubber,
particularly when used as a tire sidewall portion.
Thi3 is considered significant as compared to
utilization of a titanium dioxide colored (in absence
of carbon black) tire sidewall.
The utilization of the prescribed grey colored
sidewall component i8 also con~idered to be useful in
pro~iding unique 3tyling distinctne~s to the tire a~
compared to tire3 without such a sidewall component~.
In one aspect, or embodiment, of the invention, a
black colored pneumatic tira i5 provided which has at
least one ~idewall containing at least one annular
groove and at lea~t one annular rib where at least one
groove and/or at least one rib cons~itutes ~aid
annular, contrastingly grey colored rubber band.
The ~aid contra~tingly grey colored rubber
componen~ i~ con~idered as being integral with the
,~
tire sidewall where both it and the remainder of the
tire sidewa}l are each compounded with sul~ur curative
and co-cured together.
Typicallyj such sidewall component, particularly
~ an annular, grey colored rubber sidewall band, or
raised identification, i9 comprised of at lea~t one
rubber selected from natural rubber and halobutyl
rubber may contain EPDM rubber and/or
~tyrene/butadiene copolymer rubber.
A~ an example, such rubber component may be
comprised o~ a mixture of natural rubber and halobutyl
rubber or a mixture of natural ~ber, halobutyl
rubber and EPDM rubber. Such sidewall rubber mixtures
are well known rubber blends often be u~ed for white
sidewall mixtures. (For example, see the Vanderbilt
35 Rubber Ha~2~ g78), page 65, "Pa senger Tire
Sidewalls-Whitel').
Preferably, the halobutyl rubber i~ selected from
at lea~t one of chlorobutyl rubber`and bromobutyl
rubber. EPDM rubber i~ an ethylene/propylene/
non-conjugated diene terpolymer rubber. Such
terpolymer rubbers are well-known.
The following example i~ intended to exemplify
features of the invention. The parts and percentages
are by weight unless otherwise indicated.
EXAMPL~ ~
Two sidewall type samples were prepared and cured
to which titanium dioxide had been added. The are
referred to herein as Exp. A and Exp. ~. Their
compositions compri~ed the material~ ~hown in Table 1.
.
:;
'
,
::
~ - I
~abla 1
__ . _ _
Part~_by Parts by
Weight
In~redienta Ex~ A Exp B
__ _ . __ _
Chlorobutyl rubber 60 60
, . _
Natural rubber 35 35
_ _
EPDM rubberl 5 5
_ . . .
Titanium dioxlde 4 4
_ _ _ _ _
Phenolic antidegradant2 1
_ _ _ __
Sulfenamide type 1.75 1.75
accelerator
__ _ _
Sulfur 1.2 1.2
I . , . . _ _ _ _ .
: Zinc oxide 5 5
I _ . _ _
~ 15 Stearic acid 1 1 .
I . . . __ . _ .
: ~ Carbon black (N-660)3 : 1 3
_ _~
Napthenic/paraffinic oil 4 4
! . - - ; ~ .
Kaolin clay 20 20
I _. . . _ _ __
Phenolfor~aldehyde resin 1.5 1.5
~ _. _ .
Hard clay 35 35
.~ __ .
: 1. EPDM rubber, an
ethylene/propylene/non-conjugated diene
terpolymer rubber.
: ~5
~ 2. Polymeric hindered phenol type.
~,$~
3. An N-660 carbon black reported as having an
iodine ab~orption ~umber of 36 and a DBP
(dibutyl phthalate) value of 90.
The Exp. A and Exp~ B cured rubbe:rs had a visibly
medium grey color.
Such compounded rubber is extruded to ~onm an
extruded rubber strip following which it i~ built into
a tire on what is to become its ~idewall and to become
an annular grey colored band or raised letters therein
and the resulting tire a~sembly ~haped and cured in a
~uitable mold a~ an elevated pressure and temperature
condition.
The rubbers had physical properties as shown in
the following Table 2.
.~
Ta~le 2
_ _ .
PropertY Exp A Ex~LB
- ~ . _
:~ Modulus, 300~ 3.3 ~ 3.4
: (MPa) _ _
~longation (~) 520 540
:: : : _
Rebound at 23C 36~ _ . _ :~
Rebound at 100C 6$ 61
. _ _ ~ _ _
The presence of the carbon black is con~idered to
,
: :. 25 ~ add a reinforcement effect to the titanium dioxide
pi$ment~containing rubber.
~ While certain repre~entati~e embodiments and
: : : detail~ have been ~hown~or the purpo~e of
illustrating the invention, it w~ll be apparent to
tho~e skilled in this~art that various changes and
modification~ may be made therein without departing
from the spirit or ~cope of the invention.
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