Note: Descriptions are shown in the official language in which they were submitted.
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_ LF LO~RICATING TIRE BEAD
This invention relates to tires having beads which are
self-lubricating.
Tire beads are usually swabbed with a soap solution or
other lubricant to facilitate mounting on metal or plastic rims.
This procedure, although strongly recommended by all tire
producers9 is not always utilized by th~ customers and tire
service centers. Serious damage or explosion can occur from
"dry" mounting tires if the beads hang up in the drop center
portion o~ a rim, and are then subjected to high pressures to
move them out to the rim flange.
OBJECTS
An object of this invention is to overcome the difficulties
alluded to hereinabove and to provide a tire with beads which
facilitate mounting when the recommended lubrication procedures
have not been followed.
These and other objects and advantages of the present
inventidn will become more apparent to those skilled in ~he art
from the following detailed description, accompanying drawing and
examples.
SUMMARY OF THE INVENTION
According to t~e pleselt ~nven~on l~c chafer of a ~ire
; contains an incompatible and migratory oil or wax which migratesto and blooms on ~he outer sur~ace of ~he chafer after curing to
provide a luhricating coat or film which permits ready mounting
(or demounting~ of a tire without the damage to the bead.
As shown in the accompanying drawing, which is a vertical
cross section of a vulcanized pneumatic tire, 1 and 1 are $he
; chafers which may ccntain Fabric and which wrap around the bead
area "A." 2 and 2 are the bead fillers. The inner liner is
shown at 3 and usually is of butyl, brominated butyl or
chlorinated butyl rubber. A carcass ply of rubberized fabric is
shown at 4. 5-5 and 6-6 are the bead bundles and rim strips,
respectively, of the tire. The white sidewall is shown at 7.
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The sidewalls are shown at 8-8, and the wingkips are shown at
9-9. The belts are shown at 10 and 10. The tire, also, contains
a tread base 11, tread cap 12 and grooves 13-130 lhe tire is
shown mounted on a wheel such as of steel containing rim flange
14~14 and a rim 15~
DISCUSSION OF DETAIL AND PREFERRED EMBODIMENTS
The incompatible and migratory oils or waxes or mixtures
thereof which form a lubricating or low friction film on the
outer surface of the chafer of the cured or vulcanized tire are
non-drying or semi-drying oil and waxes containing ester groups
and may, also, contain hydroxyl groups and carbon to carbon
double bond unsaturation. They may be partly hydrogenated. They
have an iodine value of below about 125 and an acid titer below
about B5DC. Examples of some materials to use are cottonseed
oil~ peanut oil, partially hydrogenated corn oil and sunflower
oil, sperm oil, lanolin, wool grease, spermaceti wax, beeswax,
shellac wax, Japan wax, candellia wax9 carnauba wax, hardened
linseed oil, coconut oil3 babassu oil, palm kernal oil, palm oil,
olive oil, castor oil (preferred), peanut oil, rapeseed oil~ beef
tallow, lard (leaf), butyl oleate~ N-octyl oleate, methyl oleate,
butyl stearate and the like and mixtures thereof. For more
information on oils and waxes, please see Warth, "The Chemistry
And Technology Of Waxes," 2nd Ed., 1956, Reinhold Publishing
Corp., New York; Bailey, "Industrial Oil And Fat Products," 1951,
Interscience Publishers, Inc., New York; Fieser and Fieser9
"Organic Chemistry," 1944, D. C. Heath And Company, Boston; "The
Merck Index," Seventh Edition, 1960, Merck & Co., Inc., Rahway,
New Jersey and "Encyclopedia of Polymer Science And Technology,"
Vol. l, pages 98-104, 665 and 683-685 (1964); Vol. 2 , page 531
(1965); Vol. 5 , pages 216, 224 and 225 (1966); Vol. 6, pages
140~ 141, 490 and 431 (1967); Vol. 8, pages 326 and 329-336
(1968); Vol. 10, pages 240 245~ 270 273 and 288-292 (1969); Vol.
12, pages 286 and 418 (1970) and Vol. 14~ pages 773-779 ~1971),
an "Intersc~ence" Publication, a division of John Wiley and Sons,
Inc., New York.
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The chafer or chaPer strip is a vulcanized rubber compound
of rubber, sulfur, accelerators, zinc oxide, stearic acid,
process oil9 ankioxidants, reinforcing carbon black and so forth
including optionally silica or silicates. The rubber can be
natural rubber, cis polyisoprene, cis polybutadiene, emwlsion
styrene-butadiene rubber, solution styrene-butadiene rubber, high
vinyl polybutadiene and so forth and mi~tures thereof. The
incompatible or migratory oil or wax is used in an amount of from
about 2 to 129 preferably about 6 parts by weight per 100 parts
by weight total of the rubber (phr) in the chafer compound. The
chafer strip can contain fiber reinforcement such as fibers, cord
or fabric (metal, glass, polyester, nylon (preferred), Aramid,
rayon or mixture thereof.) Prior to incorporation with the
rubber compound of the chafer the fiber reinforcement can
depending on the type of fabric3 optionally be coated with an
aqueous adhesive dip and then dried of a composition of a
resorcinol- or phenol-formaldehyde resin and a latex of a
butadiene-styrene-vinyl pyridiene rubbery terpolymer.
While the present invention is particularly concerned with
vehicle pneumatic tires such as passenger, truck, off-the-road,
farm, airplane, giant, motorcycle, bicycle, trailer, recreational
vehicle and the like tires, it, also, can be applicable to other
tires such as solid tires~ The tires can be bias, bias-belted or
radial (preferred) tires.
The following examples will serve to illustrat~e the present
invention with more particularity to those skilled in the art.
For these examples laboratory tests were first run and then
tires were built in the customary way~ molded and vulcanized.
All of the tirès contained chafer strips of the same rubber
compound except that the chafers of one group of tires contained
6 phr of castor oil in the chafer compound while for the other
group (the controls) the chafer compound did not contain any
castor oil or other incompatible and migratory ester containing
oil or wax.
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The results are shown in the examples below.
Example 1
Laboratory compositions suitable for chafer strips were
prepared and cured. These were 61'x6llxoO70'l and contained varying
amounts of castor oil. They were tested for surface lubricity at
0.1~ 0.2, 0.4 and 0.6 phr. There was not any evidence of the
formation of a surface film on the test chafer strip even after
several days. On the other hand, when the same tests were run
with 2, 4, 6 and 8 phr in the sample cured chafer strips, there
was evidence in a short time (1 or 2 days) of a satisfactory
lubricating ~ilm on the surface of the test strips.
Example 2
Tires were machine mounted with no mounting lubricant used
for any of the tires. The rims were, in fact, cleaned with
OHLOROTHENE* between tire tests. The data in Table I on bead
seat pressures clearly indicates the ease of mounting facilitated
by the use of an incompatible and migratory oil. With tire group
B~ the beads mounted and seated with barely an audible sound.
Tires in group A had the usual characteristic sounds during0 mounting as well as the popping noise when the beads seated.
Table I
P185/80R-13 RADIAL PASSENGER TIRES
Rim Size 5/13
Bead Seat Pressures (PSIG)
25 GROUP A - No castor oil
in chafer csmpound N = 6 (tires)
Serial Side
Mean 8.08
Standard Dev. 2.400 Opposite Side
Mean 7.25
Standard Dev. 2.02
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Table I (cont'dl
GROUP B - 6 phr cas-tor oil in chafer compound N = 6 (tires)
Serial Side
Mean 2.75
Standard Dev. .274
Opposite Side
Mean 2.92
Standard Dev. .59
The castor oil in the rubber compound of chafer strip does
not appear to adversely affect the tack (building tack) of the
chafer strip so that it readily adheres to the bead components
during tire building~ molding and curing
*-l,l,l-trichlorethane, The Dow Chemical Company~
Example 3
Table II
PASSENGER TIRE STEP SPEED TEST TO TIRE FAILURE
Rim Size 5xl3
Tires were P185J80R-13 Radial Tires
Speed Miles @
Miles @ (mph) @ Failure
Tire Number Failure Failure Speed Failure_Mode
1 414 105 8 Belt edge separation
opposite side*
2 435 105 - 29 Belt edge separation
opposite side*
3 446 105 40 Belt edge separation
opposite side*
(Avg.) (432)
4 423 105 17 Belt edge separation
: serial side*
5 419 105 13 Belt edge separation
serial side*
. (Avg-) (421)
*Crown of the tires
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Tires l to 3 did nok contain any castor oil ~n the chafer
strips. Tires 4 and 5 contained 6 phr of castor oil in the
chafer strip. There was no significant d1fference between groups
with all failures at lOS mph. This test indicates that the
S castor oil does not contribute to tire failure on step speed
tests.
Example 4
Table III
PASSENGER TIRE STEP LOAD TEST TO TIRE FAILURE
Rim Size 5x13
Tires were Pl85/80R-13 Radial Tires
Miles @
Miles @ % Load Failure
Tire Number Failure ~ Failure Load Failure Mode
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15 10 5052 240 15? Blow out lower opposite
sidewall*
11 4923 240 23 Blow out lower opposite
sidewall*
(Avg.) (4988)
20 12 5194 240 294 Blow out opposite
sidewall*
13 5284 ?40 384 Blow out opposite
sidewall*
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(AV9-) (5239)
*Sidewall of the tire, not in the bead.
Tires lO and 11 did not contain any castor oil in the
chafer strips. Tires 12 and 13 contained 6 phr of castor oil in
the chafer strips. There was no significant difference between
groups with all failures at 240% load. This test indicates that
castor oil in the chafer strips does not affect blow out when the
tires are run to failure.
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Table IV
BEAD UNSEATING TEST TIRE PRESSURE - 26 PSI
Rim Si~e 5x13
5Tires were P185/80R-13 Radial Tires
TIRE NUMBER LOAD
. 3548
21 3622
22 3621
10(Avg.) (3597)
23 3535
24 3532
3~62
(Avg.) (3576)
15Three tires from each group were tested for bead unseating
with no difference between groups. Tires 20 to 22 did not
contain any castor oil in the chafer compound. Tires 23 to 25
oontained 6 phr of castor oil in the cha~er compound. These
tests showed that tires 2~ to 25 stayed on the rim of the wheels
in:spi:te of the fact that the chafers contained castor oil or
that the beads were self-lubricating, D.O.T. minimum is 2300.
Example 6
Table V
TRAP WELL MOUNTING TRIAL
: 25 . : Rim Size 5xl3
Tires were P185t80R-13 Radial Tires ~ :
-TIRE ~UMBER : TIRE PRESSURE~@ BEAD SEATI ~ PSI~
: :2~.0
: : 31 22.0
: 30 ~ : 3~ ~ 12.0
(Avg.~ : (18~0~ : :
33 12.0
:: ~ 34 : 13.0
8.0
3S (AV9.~ (11.0
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A tube was placed inside of the tire with no mounting
lubricant used. A section of the bead was forced lnto the rim
well by hand and air added to the tube until the bead section
being forced into the rim well was pushed out and seated. The
tire pressure was then measured. There was a significant
difference in the pressures at bead seating between tires 33 to
35 and tires 30 to 32.
The chafer strips of tires 30 to 32 did not contain any
castor oil while the chafer strips of tires 33 to 35 contained 6
phr of castor oil in the rubber compound of the chafer strip.
Tires 33 to 35 slipped out of the wheel well at low pressure.
Example 7
Table VI
TANGENTIAL LOAD DEFLECTION
Rim Size 5x13
Tires were P185/80R-13 Radial Tires
Radial Load 1300 Lbs.
Tire Pressure 35 PSI
Tangential Load Tangential
T~re Number@ Slippage (Lb ~Deflection 1 ns.)
2150 2.2
41 2200 2.3
(Avg.) (2175)
42 2250 2.4
~3 2050 2.2
(Avg.) (2150)
Tab e VI (Cont'd3
Tire Pressure 26 PSI
~ Tangential Load Tangential
Tire Number@ Slippage ~Lbs.)
2~25 2.~
41 20?5 2.2
(Avg.) (2025)
42 2000 2.3
43 1900 202
(Avg.) (1950)
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When slippage finally occurred it was between the tread
surface and the steel grid plate against which it was loaded.
Crayon marks indicated no slippage of the beads against the rim.
Tangential load deflection was run at 35 psi and 26 psi
tire pressures~ There was no significant difference between
groups in tangential load or deflection for either tire pressure
tested,
This test shows that there was not any bead slippage under
the applied tangential load for either group of tires. Tires 40
and 41 did not contain any castor oil in the rubber compound of
the chafer strip. Tire 42 and 43 continued 6 phr in the rubber
compound of the chafer strip.
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TABLE VII
lS VEHICLE BRAKIN~ TEST
Rim Size - 5xl3
Tires were P185/80R-13 Radial Tires
Tire Pressure - 35 PSI
Vehicle - Pontiac J2000
Tire Slippage When Bead
Tire Tire Slippage When and Rim Lubricated
NumbPr Position Dr,y Mounted ~Soap Solution)
LF No slippage 2 1/?" slippage
51 RF No slippage 2 lt?" slippage
~ 25 52 LR No slippage No slippage
- 53 RR No slippage No slippage
Tires 50 to 53 were mounted with and without lubricant and
tested in all positions on a front wheel drive Pontiac J-2000.
No rim slippage occurrled on braking when dry mounted. Slippage
occured when the mounting lubricant was used which is typical for
some tires. The chafer compounds of tires 50 to 53 contained 6
phr of castor oil in the rubber compounds of the chafers.
The level of slippage noted on the front tires was no more
than has been observed when using a soap solution or other
conventional lubricant and running this type of test.
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