GB1583540A - Pneumatic tyre - Google Patents

Description

(54) PNEUMATIC TIRE (71) We, THE GENERAL TIRE & RUB- BER COMPANY, a corporation organized and existing under the laws of the State of Ohio, of One General Street, Akron, Ohio, United States of America, do hereby declare the invention, for which we pray that a patent may be granted to us, and the method by which it is to be performed, to be particularly described in and by the following statement: - This invention relates to a pneumatic tire.

A great deal of effort, in the past, has gone into attempts to make automobile tires more reliable. Reliability has improved to the point where automobile manufacturers are considering eliminating the spare tire to save space. Unfortunately, the reliability of tires still leaves much to be desired.

The use of ribbon wire in tires to solve various problems has been disclosed in U.S.

Patent 4,011,899 Chamberlain (1977), U.S.

Patent 3,667,529 Mirtaln (1972), and Daniels B. K. "Steel Ribbon Belt Reinforcement Mechanics" Tire Science and Technology, TSTCA, Vol. 5, No. 1, Feb. 1977.

Prior art patents which disclose the use of puncture sealant compositions in tires include U.S. Patent 3,903,947 Emerson (lug75) and U.S. Patent 3,935,893 Stang, et al. (1976). The Emerson patent utilizes a partially cured ethylene propylene nonconjugated diene rubber in combination with other ingredients as a sealant.

The Daniels reference discloses that ribbon wire tires probably will hold nails more firmly, thus, allow them to run longer without deflation.

The Stang, et al. patent utilizes a mixture of high molecular weight curable isobutylene, isoprene, low molecular weight curable isobutylene, isoprene, liquid butylene as a tackifier partially hydrogenated styrene isoprene carbon black cross-link and initiator. While these puncture sealants were effective to a degree in rigid thick-walled four-ply bias tires, they were not so effective in the flexible two-ply radial tires.

By four-ply and two-ply is meant body plies. The prior art, in attempting to solve the air loss due to puncture problems, has not suggested the functional relationship which can exist between ribbon wire and puncture sealant in solving the problem of air loss due to puncture and the removal of the puncturing object.

According to the present invention there is provided a pneumatic tire having an air chamber, beads, a carcass reinforced with one or more carcass plies, a tread surrounding the crown region of the carcass and one or more tread reinforcing belt plies disposed circumferentially about the crown region of the carcass between the carcass and the tread, wherein at least one reinforcing ply of the belt comprises flat steel wires, the wires being at least twice as wide as they are thick, with the wide faces of the wires being perpendicular to the radius of the tire, and there is a layer of a puncture sealant between the air chamber and the belt reinforcing ply or plies.

Evidence obtained indicates that in such a structure a functional relationship exists between the ribbon wire plies in the belt and the puncture sealant which greatly reduces leaks due to nail punctures in the tire. The ribbon wire preferably has a thickness of 0 1 to 0 5 mm preferably 0 2 to 04 and a width of 02 to 60 mm, prefer ably 05 to 20 mm.

The ribbon wire can be made by either rolling a steel wire to a flat configuration or by cutting a steel sheet to form ribbon.

The ribbon wire is preferably brass plated.

The ribbon wire in the tire is positioned in the belts so that it is perpendicular to the radius of the tire. Preferably the ribbon wire plies of the tire are at an angle of from 15 to 30 to the circumferential centerline of the tire and at an angle of from 30 to 60 with respect to each other. In other words, they are laid at a bias angle similar to the steel cords in conventional tires.

Also, preferably the steel ribbon wire covers from 50 to 980/0, preferably 80 to 90o of the entire tread area, assuming that the tread area has no depth. The tire prefer ably is a one or two ply radial tire having curved sidewalls and a thick, rigid tread with a broad groove width.

A typical recipe for a preferred sealing composition of this invention comprises 100 parts by weight of an EPDM rubber, 100 to 180 parts, preferably 120 to 140 parts by weight per 100 parts of rubber of a paraffinic oil, 10 to 50, preferably 15 to 30 parts by weight per 100 parts rubber of a coarse particle size carbon black, 2 to 8, preferably about 5 parts by weight per 100 parts rubber of a heat stabilizer such as zinc oxide and 1 to 3, preferably about 2 parts by weight per 100 parts rubber of an antioxidant such as the commercial high temperature condensation product of acetone and diphenylamine.

Separating and covering layers or squeegee sheets encapsulating the puncture sealant may be provided and can serve two major functions. The first is mechanical in that they prevent the uncured or slightly cured sealant from sticking to the curing bladder used in vulcanizing the green tire.

The second function is to prevent migration of plasticizer oils out of the sealant layer.

It is preferred in this invention to utilize nitrile rubbers having medium to high acrylonitrile contents of at least 20 weight percent, more preferably at least 30 weight percent acrylonitrile, in the squeegee sheets.

Typical suitable nitrile rubbers generally contain about 30 to 35 weight percent acrylonitrile units and range in Mooney viscosity (ML1 + 4 at 212"F) from about 30 to about 60. Nitrile rubbers are widely known as extremely resistant to paraffinic oil.

Therefore, the use of nitrile rubber in the separating and covering sheets effectively prevents the paraffinic oil employed in the synthetic rubber sealing composition from migrating therefrom. It is preferred that the nitrile rubber comprise at least about one-half of the total rubber content of the separating and covering sheets. In place of part or all of the nitrile rubber there can be used a rubbery vulcanizable copolymer of propylene oxide and allyl glycidyl ether containing from about 0-5 to 10o by weight of copolymerized allyl glycidyl ether or similar propylene oxide rubber.

Since the separating and covering sheet compositions are vulcanized, they must necessarily contain ingredients for effecting vulcanization along with a number of other additives to get the desired properties. The total amount of these materials may range from 50 to 150 parts by weight per 100 parts by weight of total rubber in the composition. Examples of these ingredients and other additives include carbon black, zinc oxide, stearic acid, accelerators, antioxidants, fillers and the like. A typical squeegee sheet formulation of this invention comprises 70 to 100 parts by weight of a medium to high nitrile hydrocarbon rubber, 0 to 30 parts by weight of natural rubber, 20 to 100, preferably 50 to 70, phr of carbon black and other filler, 0 to 20 phr of tackifier, 0 8 to 1 6 phr of sulfur and 1 to 10 phr of stabilizers, accelerators, antioxidants and other additives. The rubbers and other ingredients are combined using conventional rubber mixing and blending practices. After the laminate is formed, the covering layers are vulcanized during the cure cycle of the tire.

An embodiment of the invention will now be described by way of example with reference to the accompanying drawings in which: - FIG. 1 is a cross-section of a tire having ribbon wire belt plies and a puncture sealant 1 encapsulated between the air chamber and the belt plies.

FIG. 2 is a view of a partially crosssection through the tread of the tire showing the bias configuration of the ribbon wire plies in the belt.

FIG. 3 is a cross-sectional view of a ribbon wire ply showing ribbon wire embedded in rubber stock (calendered wire).

Figure 1 shows a radial tire having curved flexible sidewalls 17 and a tread 13.

The tread 13 preferably is a relatively stiff compound which resists flexing having broad grooves 2. The sidewalls 17 are curved and flexible so that the tire will run smooth. The stiff tread 13, the broad grooves 2 and heavy tread ribs 21, it is contemplated, will prevent movement of a nail after it has penetrated the tire and, thus, reduce the amount of enlargement of the hole. The sidewalls contain two plies 19 and 20 which extend radially from bead 15 to bead 15 of the tire and overlap beads 15. Positioned under the tread 13 are two belt plies 9 and 11. The belt plies are made of ribbon wire strands 23 as shown in FIG.

2. The ribbon wire was obtained from Baekert, a major wire supplier located in Belgium. The number for the wire is V4554 ribbon wire. The wire is brass plated, has a thickness of 25 mm and a width of 1 0 mm. The wire has a break strength of 556 Newtons and it is used at an end count per inch of 15. To produce the belt ply, the rubber wire is calendered with rubber to a thickness of about 1 39 mm.

The angle of the ribbon wire cords to the circumferential centerline of the tire after cure is about 22". Positioned under the ribbon wire and the two cord ply is the puncture sealant 1. The puncture sealant contains: 60 parts of Nordel 1070 (Nordel is a Registered Trade Mark), ethylene pro pylene non-conjugated diene rubber avail- able from duPont; 40 parts of ethylene pro pylene ethylidine norbornene. This m - terial is available as Epsyn 70 from Copolymer Rubber and Chemicals Co., Baton Rouge, La. It is a zinc oxide-phenolic resin curable gdm; 120 parts of a high viscosity paraffinic oil available as Sunpar 2080 from the Sun Oil Company; 15 parts of Astin Black. Austin Black is bitumnous coal fines available from the Slab Fork Coal Co., and/or Columbia Carbon; 2 parts BLE-25 amine antioxidant, a diphenyl amine-acetone reaction product available from Uniroyal Chemical, Naugatuck, Conn.; 12 parts of SPlQ55 bromThated phen colic, a bromornethyl alkyl phenyl formaldehyde resin available from Schenectady Chemicals.

To partially cure the puncture sealant, the tire containing the sealant is subjected to the cure procedure set forth below. The combination of the zinc oxide and the brominated phenolic causes cross linking of the Epsyn 70A EPDM only. For further details as to the making and encapsulation of the puncture sealant, see U.S. Patent 3,903,947 of Emerson (1975).

The puncture sealant composition is encapsulated in a nitrile rubber envelope formed by separating and covering layers 3, 5. The nitrile rubber envelope is incompatible with the puncture sealant composition and does not bond to it during curing. The nitrile envelope 3, 5 contains 100 parts by weight of a nitrile hydrocarbon rubber, 35 parts of a HAF, high abrasion furnace black, 20 parts of Austin Black, 2 parts of n-cyclohexyl-2-benzothiazole-sul- fenamide and 1-2 parts of sulfur. The rubber and other ingredients are combined using conventional rubber mixing and blending practices. The covering layers are cured and the puncture sealant is partially cured during vulcanizing of the tire. The tire is cured for 20 minutes using 1379 kilopascals (kPa) at a steam temperature of 196"C followed by 92 minutes of hot water at 1724 kPa at 1660C followed by eight minutes of circulating water at 38"C at 1724 kPa input. Care should be taken not to lose pressure inside the tire between the curing steps. For further details concerning the nitrile rubber envelope, see U.S.

Patent 3,903,947 of Emerson (1975).

The puncture sealant is extruded onto one sheet of uncured nitrile rubber after which a second sheet of nitrile rubber is placed over the sealant as a cover. To prevent flow, the cover can be sectioned into a multiplicity of compartments. The tires are made in a conventional manner using somewhat longer cure cycles. If a conventional spray type sealant is used, the tire is cured in a normal manner. In making the tire, first the inner liner 7 is placed on the building; drum then the sealant package 1, 3, 5 is centered on the building thrum arid a sheet of fiber filled- squeegee 24, ply beads and other conventional c6-mporien'ts are added to the tire in the converitional man- ner. The fiber filled squeegee 24 prevents cords from pulling through the sealant package. The sealant packages us d in making the tires of the present invention were quite old and the age, plus other factors, influenced the flow properties of the sealant.

The sealant, after the tires were cured, was somewhat more flowable than expe-eted.

To compare the present invention with the prior art, a n--uni6er of tires were built using the combination of the ribbon wire in the belt plies and the sealant package between the inner liner and the body plies. The tire size was GR78-15. The body plies were two radial ply polyester. The tires had a normal inflation pressure. Nails were driven into the tires and then removed from the tires to determine whether or not a leak would occur. Half of the nails used were six penny nails and half of the nails used were sixteen penny nails. In 96% of the cases, no air loss occurred after removal of the nails. The same test had been run earlier using tires made from the same encapsulated sealant and having cable wire in the belt plies. Only 39% of the tires retained their air pressure on removal of the nails. Inspection of the nails removed from the ribbon wire belt tires shows that not only was sealant scraped from the surface of the nails, but also that metal was scraped from the surface.

It is contemplated that a sealant such as the commercially available Rocket Research sealant will be comparable or even better than the sealant used above. It is contemplated that the nitrile rubber cover of the sealant package used above tended to wipe off from the sealant before the nail entered the opening in the tread.

In this application, all parts and percentages are by weight unless otherwise specified.

Body plies may also be made using ribbon wire.

The present invention is not based upon the concept of making a tire or belt plies using ribbon wire or the sealant composition. These are old and well known in the art and, therefore, will not be described in detail in this application. It is believed that any type of tire reinforcing ribbon wire and any type of tire puncture sealant will work in the present invention. The present invention is based upon the synergistic combination of ribbon wire and puncture sealant.

WHAT WE CLAIM IS: - 1. A pneumatic tire having an air chamber, beads, a carcass reinforced with one or

**WARNING** end of DESC field may overlap start of CLMS **.

Claims (3)

**WARNING** start of CLMS field may overlap end of DESC **. pylene ethylidine norbornene. This má- terial is available as Epsyn 70 from Copolymer Rubber and Chemicals Co., Baton Rouge, La. It is a zinc oxide-phenolic resin curable gdm; 120 parts of a high viscosity paraffinic oil available as Sunpar 2080 from the Sun Oil Company; 15 parts of Aùstin Black. Austin Black is bitumnous coal fines available from the Slab Fork Coal Co., and/or Columbia Carbon; 2 parts BLE-25 amine antioxidant, a diphenyl amine-acetone reaction product available from Uniroyal Chemical, Naugatuck, Conn.; 12 parts of SPlQ55 bromThated phen colic, a bromornethyl alkyl phenyl formaldehyde resin available from Schenectady Chemicals. To partially cure the puncture sealant, the tire containing the sealant is subjected to the cure procedure set forth below. The combination of the zinc oxide and the brominated phenolic causes cross linking of the Epsyn 70A EPDM only. For further details as to the making and encapsulation of the puncture sealant, see U.S. Patent 3,903,947 of Emerson (1975). The puncture sealant composition is encapsulated in a nitrile rubber envelope formed by separating and covering layers 3, 5. The nitrile rubber envelope is incompatible with the puncture sealant composition and does not bond to it during curing. The nitrile envelope 3, 5 contains 100 parts by weight of a nitrile hydrocarbon rubber, 35 parts of a HAF, high abrasion furnace black, 20 parts of Austin Black, 2 parts of n-cyclohexyl-2-benzothiazole-sul- fenamide and 1-2 parts of sulfur. The rubber and other ingredients are combined using conventional rubber mixing and blending practices. The covering layers are cured and the puncture sealant is partially cured during vulcanizing of the tire. The tire is cured for 20 minutes using 1379 kilopascals (kPa) at a steam temperature of 196"C followed by 92 minutes of hot water at 1724 kPa at 1660C followed by eight minutes of circulating water at 38"C at 1724 kPa input. Care should be taken not to lose pressure inside the tire between the curing steps. For further details concerning the nitrile rubber envelope, see U.S. Patent 3,903,947 of Emerson (1975). The puncture sealant is extruded onto one sheet of uncured nitrile rubber after which a second sheet of nitrile rubber is placed over the sealant as a cover. To prevent flow, the cover can be sectioned into a multiplicity of compartments. The tires are made in a conventional manner using somewhat longer cure cycles. If a conventional spray type sealant is used, the tire is cured in a normal manner. In making the tire, first the inner liner 7 is placed on the building; drum then the sealant package 1, 3, 5 is centered on the building thrum arid a sheet of fiber filled- squeegee 24, ply beads and other conventional c6-mporien'ts are added to the tire in the converitional man- ner. The fiber filled squeegee 24 prevents cords from pulling through the sealant package. The sealant packages uséd in making the tires of the present invention were quite old and the age, plus other factors, influenced the flow properties of the sealant. The sealant, after the tires were cured, was somewhat more flowable than expe-eted. To compare the present invention with the prior art, a n--uni6er of tires were built using the combination of the ribbon wire in the belt plies and the sealant package between the inner liner and the body plies. The tire size was GR78-15. The body plies were two radial ply polyester. The tires had a normal inflation pressure. Nails were driven into the tires and then removed from the tires to determine whether or not a leak would occur. Half of the nails used were six penny nails and half of the nails used were sixteen penny nails. In 96% of the cases, no air loss occurred after removal of the nails. The same test had been run earlier using tires made from the same encapsulated sealant and having cable wire in the belt plies. Only 39% of the tires retained their air pressure on removal of the nails. Inspection of the nails removed from the ribbon wire belt tires shows that not only was sealant scraped from the surface of the nails, but also that metal was scraped from the surface. It is contemplated that a sealant such as the commercially available Rocket Research sealant will be comparable or even better than the sealant used above. It is contemplated that the nitrile rubber cover of the sealant package used above tended to wipe off from the sealant before the nail entered the opening in the tread. In this application, all parts and percentages are by weight unless otherwise specified. Body plies may also be made using ribbon wire. The present invention is not based upon the concept of making a tire or belt plies using ribbon wire or the sealant composition. These are old and well known in the art and, therefore, will not be described in detail in this application. It is believed that any type of tire reinforcing ribbon wire and any type of tire puncture sealant will work in the present invention. The present invention is based upon the synergistic combination of ribbon wire and puncture sealant. WHAT WE CLAIM IS: -

1. A pneumatic tire having an air chamber, beads, a carcass reinforced with one or

more carcass plies, a tread surrounding the crown region of the carcass and one or more tread reinforcing belt plies disposed circumferentially about the crown region of the carcass between the carcass and the tread, wherein at least one reinforcing ply of the belt comprises fiat steel wires, the wires being at least twice as wide as they are thick, with the wide faces of the wires being perpendicular to the radius of the tire, and there is a layer of a puncture sealant between the air chamber and the belt reinforcing ply or plies.

2. A tire according to Claim 1 wherein the tire is a radial tire and the reinforcing belt plies comprise two adjacent plies of flat wires, the wire of each belt ply being disposed at an angle to the circumferential centerline of the tire of from 15 to 300 and at an angle of from 30 to 60 with respect to each other.

3. A tire substantially as described herein with reference to and as shown in the accompanying drawings.