JPS5855002B2 - Cordless tires for vehicles and their manufacturing method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a novel cordless tire for vehicles and a method for manufacturing the same.

Typical vehicle tires, including cords, are highly uneven and almost always require balancing when installed on a vehicle to provide smooth running and even tire wear.

If tires could be obtained that were significantly more uniform in weight distribution than conventional tires, significant advances would be made in eliminating balancing costs and improving ease of operation.

Previous attempts to produce such tires have been unsuccessful, and all currently available commercially available tires must be balanced, which is virtually impossible to achieve perfectly. .

Another problem posed by conventional tires is that in order to achieve proper rubber-to-tire adhesion, the cord must be coated with one or more layers of complex adhesive compositions, which can be expensive. This requires the use of equipment.

Typical tire cords also have problems caused by factors such as stiffness, and a tendency to be attacked by certain rubber hardener by-products, and by nylon, which occurs when the tire is held in a shaded position. A problem arises where force is applied.

Furthermore, the elastomeric matrix of the tire carcass, which consists of conventional rubberized layers, tends to be non-uniform, thus causing the tire carcass to harden unevenly.
and generates a potential weak L) ton.

Ease and speed of manufacture are important factors in making tires.

Prior to the present invention, tires made from polyurethane had to be cured for relatively long periods of time.

The present invention generally allows the polyurethane to be cured in about 2 minutes or less to about 6 minutes, while premature curing can be very easily avoided.

According to the present invention, there is provided a cordless tire for a vehicle comprising a sidewall of a polyurethane nitrogen bonded to a tread of an ethylene/propylene/non-conjugated diene elastomer, wherein the sidewall of the polyurethane reacts an organic diisocyanate with a poly(alkylene oxide) glycol. to make an incyanate-terminated prepolymer, which is mixed with sodium chloride, sodium bromide, sodium iodide, sodium nitrite, lithium chloride, lithium bromide, lithium iodide,
consisting essentially of a product cured by reaction with methylene dianiline introduced into the prepolymer in the form of a complex with a salt selected from the group consisting of lithium nitrite or sodium cyanide; An improved tire is provided, wherein the methylene dianiline is liberated from the complex by heating the complex-containing prepolymer mixture.

According to the invention, the mold also includes a material selected from the group consisting of sodium chloride, sodium bromide, sodium iodide, sodium nitrite, lithium chloride, lithium bromide, lithium iodide, lithium nitrite and sodium cyanide. The sidewalls of the carcass are prepared by adding an incyanate-terminated prepolymer prepared by the reaction of a poly(alkylene oxide) glycol containing a dispersed complex of a salt and methylene dianiline; Rapid production of a cordless tire for a vehicle, characterized in that the mixture is cured by heating to 0.degree. law is provided.

The tire is sufficiently cured to be demolded within about 100 seconds to 6 minutes, providing a rapid method of manufacturing tires.

The polyurethane is bonded to the tread and thus can be cured while bonded thereto.

The polyurethanes useful in making the tire sidewalls of the present invention are castable liquid prepolymers that are cast to yield durable, cured vehicle tire sidewalls.

A particularly suitable product is a liquid isocyanate-terminated prepolymer containing about 6.3% by weight NCO groups and 1 mole of polytetramethylene oxide glycol (number average molecular weight 1
．． 000) and 2 moles of 2,4-tolylene diisocyanate at 80° C. for 3 to 4 hours.

One type of liquid incyanate-terminated polyurethane has a number average molecular weight of at least 750 at about 50-100°C.
It is made by heating a polymerized glycol with a molar excess of organic diisocyanate to form an isocyanate-terminated prepolymer.

The molar ratio of diisocyanate to polyol used is approximately 1
．． 2 to 4.1, preferably about 1.5 to 3.0.

If this molar ratio is close, there will be some free organic diincyanate in the polymer.

The presence of free diisocyanates in the polymer is particularly undesirable when using high molecular weight glycols, as this has the effect of reducing the viscosity of the mixture.

The molecular weight of the polymerized glycol and the molar ratio of organic diisocyanate to glycol should generally be selected such that the incyanate-terminated prepolymer is liquid.

A poly(alkylene oxide) glycol is reacted with a molar excess of an organic diisocyanate to form an incyanate-terminated polymer.

These glycols are of type 4 have.

However, although R is an alkylene group, it does not necessarily have to be the same in each case, or it is an integer such that the number average molecular weight of the glycol is at least 750.

These glycols are made by polymerizing cyclic ethers such as ethylene oxide, propylene oxide, dioxalane or tetrahydrofuran.

Suitable polyalkylene ether glycols for the purposes of this invention are poly(tetramethylene oxide) glycol and poly(propylene oxide) glycol.

Polyalkylene oxide-thiooxide glycols made by condensing various glycols with thioglycols in the presence of a catalyst such as p-toluenesulfonic acid can also be used.

Polyalkylene-arylene oxides that can also be used are similar to polyalkylene ether glycols except for the presence of an arylene group.

In general, phenylene and naphthylene groups with or without substituents such as alkyl or alkylene groups are preferred.

These polymeric glycols are conveniently made by reacting a cyclic ether, such as ethylene oxide, with an arylene glycol.

Among the organic diisocyanates used are aromatic, aliphatic, and cycloaliphatic.

Toluene-2,4-diisocyanate and 4,4'-methylene diphenyl diisocyanate are preferred.

Other representative diisocyanates, such as 4-methyl-1
- 3-cyclohexane diisocyanate, 4-methoxy-m-phenylene diisocyanate, 4,4'-biphenyl diisocyanate, etc. can be used.

The active hydrogen-containing organic compound used to cure the prepolymer is methylene dianiline.

They are used in the form of complexes derived from diamines and selected organic salts.

The curing agent is prepared by complexing 4,4'-methylene dianiline with a salt selected from sodium and lithium nitrites and halides other than fluoride and sodium cyanide.

Among the compositions which can be used in particular as curing agents for urethane prepolymers are the reaction products of 3 moles of 4,4'-methylene dianiline and 1 mole of the salts listed below.

These salts are sodium chloride, sodium bromide, sodium iodide, sodium nitrite, lithium chloride, lithium bromide, lithium iodide, lithium nitrite or sodium cyanide.

Because of their availability and cost, complexes derived from 4,4'-methylene dianiline and sodium or lithium chloride are particularly preferred.

The most preferred single complex is that obtained from 4,4'-methylene dianiline and sodium chloride.

There are various methods for making the complexes of the present invention.

One method of making the complexes of the present invention is to prepare an aqueous solution containing a salt of sodium or lithium selected from the group consisting of chloride, bromide or iodide with 4,4'-methylene dianiline (hereinafter referred to as MDA) and water. This method involves reacting solid MDA in a solvent that dissolves both MDA and MDA, such as alcohol, or in the absence of substantially any solvent.

If the salt is present in a relatively dilute concentration, e.g.
% to about 12% by weight, it is preferred to use a solvent for MDA.

If the salt concentration is 12% by weight or more, no solvent is used, but solid MDA crystals are added directly to the salt solution.

The crystalline precipitate resulting from the interaction of salt and MDA is separated from the liquid, for example by filtration.

The precipitate has a molar ratio of MDA to salt of 3:1 and can be separated into its original components by adding a solvent such as acetone at elevated temperatures of about 40° to 100°C depending on the volatility of the solvent. can.

In the solvent method of making the complex, a relatively dilute aqueous solution (1-12% by weight) of the sodium or lithium salt of chloride, bromide, iodide or nitrite is heated at about 20-60°C in a suitable solvent, such as methanol. Mix with a solution of MDA at a temperature of .

Under these conditions, MDA reacts with the sodium or lithium salt to form a crystalline precipitate consisting of a 3:1 molar ratio of MDA and salt.

The crystalline precipitate is then separated from the mother liquor by filtration, decantation, centrifugation or other suitable manipulations.

In methods using highly concentrated (greater than about 12% by weight) salt solutions, the stoichiometric amount of solid crystalline MDA required to react with the amount of salt present greater than about 12% by weight Add to the salt solution with stirring at a somewhat elevated temperature of about 50-90°C.

Under these conditions, 3 moles of MDA react with 1 mole of salt to form a crystalline precipitate, which can be separated by filtration, decantation, centrifugation or other suitable methods.

Complexes of other salts, such as ammonium nitrite, can be made in substantially the same manner as for the sodium chloride complex.

The fine powder complex and the liquid prepolymer complex can be mixed using a dough mixer, a high speed impeller mixer, a paddle type mixer, or the like.

For best results, it is preferable to further mix (or disperse) the mixture obtained in a mixer of the type described above, for example using a three-roll mixer used in the manufacture of paints and inks. .

Improved dispersions are obtained even in colloid mixers.

These various mixers and kneaders are manufactured by Reinhold (R
Published by e1nhold ) in 1964 Tau I) -L
--W.J. Mead, "The...
The Encyclopedia of Chemical Process Equipment
ofChemical Process Equipm
ent) described in J.

The complex can also be used dispersed in an inert carrier liquid that is compatible with the polyurethane.

Among the suitable liquids are aromatic ester plasticizers such as tetraethylene glycol di(2-ethylhexoate) and higher aromatic hydrocarbon oils such as shell oil (5h
Dutrex manufactured by ELL Oil
) Contains 739 oil.

The use of such dispersants simplifies metering operations and reduces the time and energy required to properly incorporate the complex and prepolymer.

When the complex and fluid prepolymer are mixed to form the polyurethane sidewall, the temperature must be kept below the decomposition temperature of the complex to avoid premature curing.

In the process of this invention, the decomposition temperature of the complex is a function of the particular complex used and the prepolymer used to disperse the complex.

Incyanate-terminated urethane prepolymer and MDA N
80°C or less for the aC1 complex, preferably about 50°C
The mixing must be done at L'.

Since the material is under pressure in the mold, no degassing step is necessary.

Since mold fixation is completed quickly, the pressure should be relieved in the shortest possible time, such as within about 3 minutes, preferably within about 2 minutes.

The prepolymer can also be injected into the mold under pressure.

Injection can be carried out in conventional types of injection equipment, such as ram or screw injection molding equipment.

The pressure required is relatively low so that it can be pumped into the mold with a pump.

The pressure must be high enough to prevent outgassing of the prepolymer.

Typically about 100-800 psi (7,03-56.
2kg/song), preferably about 250-500psi (
A pressure of 17.6 to 35.2 to 9/c4) is sufficient.

Higher pressures can be used if necessary and practical.

Pressure can also be obtained from any pressure source.

The temperature used during curing of the urethane prepolymer is 100-1
60°C, preferably about 110-13Q°C.

It is preferable that the temperature is higher within this range.

This is because the curing of the urethane prepolymer is accelerated.

However, the temperature must not be so high as to cause the product to decompose.

Curing sufficient to permit demolding is typically accomplished within about 3 minutes, preferably within about 2 minutes, and most preferably within about 100 seconds.

At the end of this time the molded product is injected or removed.

The product is virtually bubble-free, with all the air remaining inside.

Generally, the amount of complex used should not be less than that which provides at least 60% of the total number of active hydrogen atoms theoretically required to react with all incyanate groups.

The preferred amount of organic compound used is such that the total number of active hydrogens present therein is about 70-100% of the total number of free incyanate groups present in the isocyanate-terminated prepolymer.

Greater or lesser amounts of active hydrogen-containing organic compounds can be used, and the number of active hydrogen-bearing groups can approach or even exceed the number of free isocyanate groups in the polymer.

The tread of the tire of the present invention is made from a cured ethylene propylene/non-conjugated diene (EPDM) copolymer;
This can be cast into the desired shape.

The most preferred elastomer for use in the tread of EPDM tires is a terpolymer containing 57.7% by weight ethylene, 40% by weight propylene, and 2.3% by weight 1,4-hexadiene, and has a Mooney viscosity. (ML-1+4
/12Fc) is 60.

Generally preferred didistomers contain 35-45% by weight propylene and 2.1-2.5% by weight 1,4-hexadiene, with the balance being ethylene.

To minimize cracking in the tolerado, at least 35
% propylene by weight must be present.

When the propylene content exceeds 45% by weight, tire wear tends to increase.

For proper sulfur cure, the diene content should be at least about 2.1% by weight.

However, to minimize tread cracks, approximately 2.5
It must be thrown below % by weight.

The Mooney viscosity is selected to provide a good balance between processability and tread strength requirements.

Copolymers with lower Mooney viscosities are easier to process than those with higher ones.

However, the higher the Mooney viscosity, the higher the strength.

A Mooney viscosity of around 60 (ML-1+4/12 PC) is most suitable.

For passenger vehicle tire applications where minimal tread cracking is important, it is important that the copolymer is substantially linear, i.e., the side chains containing a large number of monomer units are substantially It is necessary that there be no.

Of course, linear copolymers also have side chains that are part of the monomer units contained in the copolymer main chain.

That is, the polypropylene units give rise to methyl side chains.

To increase linearity, 1,4-hexadiene (
or other monoreactive acyclic nonconjugated diene), the rate of change of about 2
The most preferred diene for L1, which must be kept below 5%, is 1,4-hexadiene.

Acyclic-reactive non-conjugated dienes are preferred dienes.

Reactive double bonds are monosubstituted double bonds, while other double bonds are di-, tri-, and tetra-substituted double bonds.

Two examples of this type are 1,4-hexadiene and 11
-ethyl-1,11-tridecadiene.

Less demanding composite tires, such as Tractor, used off-road, use branched copolymers and less preferred non-conjugated dienes, such as bicyclic dienes such as 5-ethyl-indene-2-norbornene, 5- methylene-2-
EPD made from a copolymer containing norbornene, 5-ethyl-2,5-norbornadiene, 5-(2'-butenyl)-2-norbornene and dicyclopentadiene.
It can have a tread of M.

Other dienes include 1,5-cyclooctadiene, tetrahydroindene, and 4-vinyl-cyclohexene.

EPDM and its manufacturing method are described in US Pat. No. 29334, for example.
8Q No. 3000866, No. 3063973, No. 3093620, No. 3095621 and No. 3260718.

Most preferably, 100 parts of 15AF carbon black (ASTM type N220) and 75 parts of paraffin petroleum oil are blended to 100 parts by weight of EPDM.

Other suitable carbon blacks are ASTM types 231 and 2.
It is 42.

Carbon blacks with lower order structures or larger particles can also be used, but the tread usage properties are not optimal.

For economic reasons, at least about 80 parts of carbon
Use black.

Using more than about 125 parts of carbon black will result in poor tread wear.

Paraffinic petroleum oils are suitable as extenders in tread compositions.

Alternatively, naphtha petroleum oil is suitable.

Aromatic petroleum oils are undesirable.

This is because unsaturated bonds consume the sulfur needed to cure the EPDM copolymer.

The amount of oil required depends on the amount of carbon black; the higher the carbon black content, the higher the oil content.

(40 phr and 100 phr oil required for 80 phr and 125 phr carbon blanks, respectively).

EPDM) can be cured with sulfur by combining various known reagents and methods.

Generally, at least 3 parts of zinc oxide per 100 parts of EPDM will be present to obtain a suitable vulcanizate concentration.

The preferred amount is 5 parts, which provides the best balance between cost and usability.

The remaining ingredients are selected to provide a bloom resistant tread where required.

Preferred bloom-free compositions include 1 part stearic acid;
2.5-3 parts of ((C4HgO)2PS2)2Zn (Monsanto Company's "Vuoco-/1/(
Vocol ) j, 1.5 parts of 2,2-dithiobisbenzothiazole, and 1.5 parts of sulfur in EPDM100
Required per unit.

Other bloom-free compositions include 1.5 parts notetraisopropylthioperoxydif↑ osphate (1so-Pro)2P-3) 2.1
．． 0 parts of 2-mercaptobenzothiazole (or 2.2
dithiobisbenzothiazole) and x, 5 parts of sulfur per 100 parts of EPDM.

Still other bloom-free systems include 2 parts zinc dibutyl dithiocarbamate, 0.5 parts tetramethylthiuram disulfide, 0.8 parts 2-mercaptobenzothiazole, and 1.5 to 2 parts per 100 parts rubber. Contains sulfur.

A bloom-prone composition contains 1.5 parts of tetramethylthiuram monosulfide, 0.8 parts of 2-mercaptobenzothiazole, and 1.5 parts of sulfur.

EPDM samples containing the curing system are typically heated to 160-204° C. for about 1-20 minutes to cause curing.

The composite vehicle tire of the present invention is made by adhering a preformed sidewall to a preformed tread.

Preformed sidewalls and treads can be made by conventional casting, compression molding, and injection molding techniques and equipment.

The tread is preferably made by injection molding a nidistomer material using conventional injection molding equipment and curing the molded product.

The preformed polyurethane sidewalls are preferably made by the casting method described above.

Either the two preformed components are combined together and bonded using a suitable adhesive, or the polyurethane is brought into contact with the tread and cured, or a mixture of these components is made and then the other components are combined. is made by contacting it with the originally made component.

When following this method, it is preferred that the tread is first created and the sidewalls are created in contact with the tread.

The preferred equipment for making the tread is a reciprocating screw injection molding machine which provides shear and additional heat.

In such equipment, sufficient heat is applied to cause curing of the EPDM in the mold cavity within about 1 to 3 minutes.

In each case the EPDM) red is preheated with adhesive or other reagents that promote proper adhesion between the tread and the sidewalls.

In a preferred embodiment of the invention, the tread is preheated by irradiation in air with ultraviolet light in an amount of at least about 3 joules/CWt, followed by 5% methylene chloride dichloride of tris-(p-incyanate phenyl)methane. A similar solution of a polymerized polyisocyanate mixture of liquid-liquid or structural formula, where for each component molecule, n = o, 1.2..., 0.3 to 0.4 for a mixture. Cover.

Other pretreatments that may be used include the conventional methods of imparting tack and adhesive properties to the EPDM polymer composition using flame, static electricity, gas, magnetic fields, ozone, and the like.

A particularly preferred method is to injection mold the EPDM red and allow it to fully cure after removal from the mold.

The curing operation of the EPDM tread is completed in the tire mold during casting of the polyurethane sidewalls.

It is also desirable to mold the sidewalls and tread with swirls or grooves on the surface to which other components adhere.

These swirls interlock when the sidewalls and tread are brought into contact, increasing the slip resistance of the tread and sidewall surfaces.

The physical properties of the sidewalls of the present invention are particularly excellent.

Its Young's modulus is 332-2520 kg/cd at 30'C
(The Young's modulus of the preferred material is 703 to 2109 kg/kg at room temperature.
cvt), the tensile strength is at least 106 kg/c4 (at least 176 kg/crlt for preferred materials), and the clean elongation is less than 5% after 1000 hours of tensile stress of 35.5 to 70.3 kg/cril. It is.

Due to these properties, the tire carcass of the present invention has excellent load carrying capacity and bending life.

EPDM) Red has excellent resistance to ozone deterioration, is tough, wear resistant and has excellent load carrying capacity.

The tires of the present invention are inexpensive, quick and easy to manufacture, substantially uniform throughout, tough, durable, and exhibit low wear.

The invention is illustrated by the following examples, in which all proportions are by weight unless otherwise stated.

Example I A. Manufacture of EPDM tread material The EPDM used had a Mooney viscosity (ML-1+14/1
21°C) is approximately 60% by weight, ethylene (55% by weight), propylene (41% by weight) and 1,4-hexadiene (4% by weight).
) consists of C monomer units.

This polymer has 0.34 g-mol sulfur-curable ethylene groups per kg.

Mix EPDM according to the following recipe to make a tored material.

5-10 with Banbury internal mixer
Mix above and above for a minute.

B. Injection molding of EPDM trend (cap) The EpDM tread sweetener made in section A above is fed to the heating barrel of a recirculating screw injection molding machine, which causes shearing and generates excess heat. .

The screw is rotated to deliver a fixed amount of plasticized, uniformly mixed material to the front end of the barrel.

Next, the rotation of the screw is stopped and the hot material is moved forward of the ram through the runner and gate into the heated molding cavity where it is vulcanized to form a uniform, seamless tread.

During the initial stages of vulcanization, constant pressure is applied to keep the screw in a forward position to strengthen the mold.

After a period of time, the screw begins to rotate and reciprocate, feeding the plasticized material to the forward end of the barrel for the next injection molding.

In a typical operation, a tread was formed for an F78-14 low profile passenger vehicle tire.

An injection molding machine capable of exerting 1225 t of clamping pressure on both halves of a single cavity mold is used.

Typically 4.5 kg (EPDM) red material is fed into the barrel at room temperature.

The reciprocating screw is hollowed out inside to allow cooling water at a normal room temperature, for example 20-24° C., to pass therethrough.

The external barrel temperatures for the feeding, compression and metering zones which are present sequentially in the barrel are 48-52°C, 66°C and 79°C, respectively.
~85°C.

Typically each area occupies about a month of barrel length.

The screw is rotated at 50 rpm for 50 seconds, during which time the charge is heated under a back pressure of about 3.5 to 17.6 kg/ca.

Associated with the metering zone is a 77.2°C nozzle adapter.

The surface of the immediately downstream nozzle is 177-194°C.

The compacted tread for 30 seconds was injected into the mold cavity at 138-149°C under a pressure of 914-1195 kg/crA, and the tread was heated for 15 seconds or more at 914-119 kg/crA.
Maintained under pressure of 5 kg/ca.

After shaping the raw material for 90 seconds, the tread thus produced is fully cured and removed.

The time for the injection molding process (the time from one mold closure to the next mold closure) is 150 seconds.

Next, put the tread in a heating chamber and heat it for 5 minutes at 190℃.
Heat to ℃.

: Clean the manufactured underside (inner edge) of the adhesive-coated EPDM tread with 1,1,1-trichloroethane;
Dry, irradiate with UV light (approximately 3 joules/crA) and coat with the adhesive composition described below.

Viscosity 155-165 poise (eventually Highly branched liquid pot (20℃) Riester.

** Slightly branched liquid polyester containing 1.7-2.0% by weight of hydroxyl substituents.

Density at 20°C 1,18? /crA1 viscosity 29
0 to 310 poise.

When dry, the coated tread is ready for use.

The coating must not wear out. D. Preparation of Incyanate-Terminated Prepolymer The inocyanate-terminated liquid prepolymer containing about 6.3% by weight of NCO groups is prepared by mixing 1 mole of polytetramethylene ether glycol (number average molecular weight 1000) with 2
mol of 2,4-tolylene diisocyanate and mixed at 80°C for 3-4 hours.

E. Preparation of a dispersion of the complex 100 parts of NaCl complex of MDA, 100 parts of di(2-ethylhexyl) phthalate and 1 part of cutisif, previously milled to below 5 μ in a fluid-energy mixer, were prepared in a ball mill for 24 hours. Mix for an hour.

F. Casting of uncorded polyurethane carcass and production of sidewalls bonded to the cured monolithic EPDM tread (coated cured EPDM made in section A above)
The red is placed inside a three-piece hot mold with a cavity in the shape of an F78-14 low profile passenger vehicle tire.

Also, insert brass-coated steel beads and wire into it.

The wire was previously coated with an epoxy coating composition (Th1xon AB-1244).

The mold is kept at 177°C. A self-curing liquid polyurethane composition was made by mixing 33 parts of a NaCl complex dispersion of MDA with 100 parts of an isocyanate-terminated prepolymer at 50°C.

This composition was heated at 300 psi (21,1 kg/crA
) into the mold cavity and leave it for about 2 minutes 1
The temperature is maintained at 77°C and the sidewalls are bonded to the carcass and tread of the tire.

The resulting tire is removed from the mold and post-cured for 2 hours at 120°C.

Claims (1)

[Scope of Claims] 1. A cordless tire for a vehicle comprising a sidewall of polyurethane nydistomer bonded to a tread of ethylene/propylene/non-conjugated diene elastomer, wherein the sidewall of polyurethane is formed by mixing organic diisocyanate with poly(alkylene oxide) glycol. Reacting to form an isocyanate-terminated prepolymer, which is combined with the group consisting of sodium chloride, sodium bromide, sodium iodide, sodium nitrite, lithium chloride, lithium bromide, lithium iodide, lithium nitrite, or sodium cyanide. consisting essentially of a product cured by reaction with methylene dianiline introduced into the prepolymer in the form of a complex with a salt selected from said complex-containing prepolymer mixture. An improved tire characterized in that the complex is released from the complex by heating. 2 Salts selected from the group consisting of sodium chloride, sodium bromide, sodium iodide, tetrium nitrite, lithium chloride, lithium bromide, lithium iodide, lithium nitrite and sodium cyanide in the form of methylene dianiline; poly(alkylene oxide) containing a dispersed complex with
forming the sidewalls of the carcass by adding an incyanate-terminated prepolymer prepared by reaction of a glycol, curing the mixture by heating the mixture to at least about 100° C., and applying the sidewalls of the resulting polyurethane carcass 1. A rapid method for manufacturing cordless tires for vehicles, characterized in that a tread consisting essentially of an ethylene/propylene/non-conjugated diene elastomer is bonded.