CA1265731A - Self-lubricating tire bead - Google Patents

Abstract

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Abstract Of The Disclosure The chafer strips of a vulcanized tire contain from about 2 to 12 phr of an incompatible and migratory oil or wax having ester groups and possibly hydroxyl groups and carbon-to-carbon unsaturation which blooms to the outer surface of the chafer strip to form a lubricating film providing the tire with self-lubricating beads. A tire having such a bead facilitates mounting or demounting of tires where the recommended lubrication procedures have not been followed.

Description

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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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' ~L2 ~j5 7~1 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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57~1 ' - ~ -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 during 0 mounting as well as the popping noise when the beads seated.
Table I

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. 2.40 0 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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- 6 -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 .
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*
. ., (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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i5 E~__5 Table IV

Rim Si~e 5x13 5Tires were P185/80R-13 Radial Tires TIRE NUMBER LOAD
. 3548 10(Avg.) (3597) 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 (Avg.) (1950) ` ' , ~: ' - ' SL~ 5 7~L
g 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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Claims (6)

Claims

1. A tire having beads containing chafer strips of a vulcanized carbon black reinforced rubber compound containing from about 2 to 12 parts by weight per 100 parts by weight total of the rubber in said compound of an incompatible and migratory ester containing oil or wax having an iodine number of below about 125 and an acid titer of below about 85°C which blooms to the surface of the chafers to form self-lubricating beads.

2. A tire according to claim 1 which is a pneumatic tire.

3. A tire according to claim 2 where said oil used in an amount of about 6 parts by weight per 100 parts by weight total of the rubber in said compound.

4. A tire according to claim 3 where said oil is castor oil.

5. A tire according to claim 1 wherein said chafer contains a fabric reinforcement which has been coated with an aqueous dip of a resorcinol- or phenol-formaldehyde resin and a latex of a rubbery copolymer of butadiene, styrene and vinyl pyridine and dried.

6. A tire according to claim 5 where said tire is a radial pneumatic tire and said oil is castor oil and is used in an amount of about 6 parts by weight per 100 parts by weight total of the rubber in said compound.