WO2008145421A1

WO2008145421A1 - Hybrid cord, particularly for a belt bandage of a pneumatic vehicle tire

Info

Publication number: WO2008145421A1
Application number: PCT/EP2008/052705
Authority: WO
Inventors: Claus Von Barneveld
Original assignee: Continental Aktiengesellschaft; Reese, Wolfgang
Priority date: 2007-05-31
Filing date: 2008-03-06
Publication date: 2008-12-04
Also published as: DE102007025490A1

Abstract

The invention relates to a reinforcement layer, particularly for the belt bandage of pneumatic vehicle tires, wherein the reinforcement layers are hybrid cords disposed parallel to each other and composed of a first twisted yarn made of a first material and a second twisted yarn made of a second material, the ends of both yarns being twisted with each other, wherein the first twisted yarn is an aramide yarn, and the second twisted yarn is a PES yarn in the form of a PET or PEN yarn. The invention further relates to a pneumatic vehicle tire comprising a belt bandage and/or a bead reinforcement made of such a reinforcement layer.

Description

description

HYBRIDKORD, ESPECIALLY FOR A BELT BELT OF A VEHICLE AIR TIRE

The invention relates to a reinforcing layer for elastomeric products, in particular for the belt bandage of pneumatic vehicle tires, wherein the reinforcements are hybrid cords, which are arranged substantially parallel to each other within the layer and from a first twisted yarn of a first material and a second twisted yarn of a second material, which are end twisted together, are constructed, wherein the first twisted yarn is an aramid yarn. Furthermore, the invention relates to a pneumatic vehicle tire, comprising a belt bandage and / or a bead reinforcement would be made of such a strength carrier.

In order to prevent an elevation of the tire in the case of pneumatic vehicle tires, in particular in high-speed deployment, by the centrifugal forces occurring during driving, it is known to provide a belt bandage in a pneumatic vehicle tire. A radial type pneumatic vehicle tire generally has an air-impermeable inner layer, a radial carcass containing strength carriers, which extends from the zenith region of the tire over the side walls to the bead region and is usually anchored there by wrapping tensile bead cores, a profiled tread radially outwardly, and between the tread and the carcass arranged on belt, which is radially outwardly covered with the belt bandage. The belt bandage can be formed in one or more layers and covers at least the belt edges. The belt bandage usually includes parallel and substantially circumferentially extending strength members in the form of cords embedded in rubber. The bandage is applied in the manufacture of tires in the form of layers with embedded in an unvulcanized rubber compound reinforcing agents that are wound or wound on the belt. The reinforcing elements are embedded in rubber by a calender or an extruder in the longitudinal direction by a group of essentially parallel thread-like reinforcing elements, which are usually pretreated with an impregnation thermally and / or for better adhesion to the embedding rubber in a manner known to the person skilled in the art go through to the jacket with the rubber compound. In the bombing with previously used devices and the vulcanization of the tire, the tire usually extends in the shoulder area by the survey by up to 2% and in the center region by up to 4% compared to the unvulcanized blank when the blank on a flat drum is wound.

The cords of the bandage are to allow a sufficient elevation in the camber and in the vulcanization mold in the tire production, so that the tire can be formed precisely, and they should ensure a good high speed capability after the completion of the tire while driving. To meet these requirements, the cords should be stretched with an effort of about 4% with moderate effort and from a higher elongation only with very high force.

A reinforcing material layer having a hybrid cord, in particular as a belt bandage for vehicle tires, has become known from EP 1 475 248 A1. The hybrid cords consist of two twisted yarns, one yarn of the cord being an aramid yarn and the second yarn being a nylon yarn. The aforementioned reinforcement layer gives the tire good high speed capability. However, when using the nylon yarn, the tire may tend to flat-spit due to increased shrinkage.

The present invention is based on the object to provide a reinforcing layer of rubberized hybrid cords for elastomeric products, in particular for the belt bandage of pneumatic vehicle tires, which is subject to only a slight shrinkage, thereby reducing the flat spotting. In addition, the reinforcement layer should be characterized by a force-strain behavior, which in Use of the reinforcement layer, in particular as a belt bandage in pneumatic vehicle tires, allows trouble-free tire construction including vulcanization and gives the tire a high-speed capability.

The problem is solved by the second twisted yarn is a polyester yarn (PES yarn). Thus, an alternative reinforcing layer is provided whose reinforcements are hybrid cords consisting of two twisted yarns, one yarn being a PES yarn while the other yarn is an aramid yarn. In particular PET or PEN yarns are suitable as PES yarn.

Essential to the invention is that, surprisingly, despite the use of aramid as one of the two yarn materials of the hybrid cord sufficient stretching during the tire manufacturing step of the camber and the vulcanization is obtainable, so that the green tire is precisely formed. In addition, the tire is well suited for high speed. It is known that aramid yarns and cords have a particularly high elastic modulus. A layer of aramid strength supports shows advantageous properties of non-shrinkage and low plastic deformation in the finished tire. On the other hand, during tire building, pure aramid support sheets prove disadvantageous because they allow too little elongation, so that the green tire is insufficiently formable and thus only poor tire uniformity can be obtained. In addition, the aramid material is expensive. Thus, aramid cords used as a strength carrier, especially in tire applications as a belt bandage, so far not advantageous as a strength carrier used. The hybrid cord according to the invention, however, has a better elongation than a pure aramid cord. He has a lower compared to an aramid / nylon cord

Shrink, because PES dimensionally stable than nylon, so has a lower shrinkage and a higher modulus. A pneumatic vehicle tire with a belt bandage according to the invention only slightly tends to flat-spotting. The hybrid cord is relatively inexpensive to purchase, because PES is inexpensive to obtain in the purchase. Only the aramid yarn of the hybrid cord has load-bearing properties, while the PES yarn serves as a filler and allows sufficient elevation during the cambering and vulcanization. Because the aramid yarn and the PES yarn are vertwistet so that the aramid yarn is arranged helically in the cord and reaches a spring-like effect, which allows the survey of the corduroy according to the invention. The tire has a high circumferential rigidity, which causes the good high-speed properties. It also allows precise shaping during tire manufacture, giving the tire good uniformity.

In addition, the elongation of the cord may be controlled by suitable dipping techniques known to those skilled in the art.

According to advantageous developments, the aramid yarn has a fineness <1680 dtex and the PES yarn has a fineness <1670 dtex. Thus, a comparatively fine hybrid cord is created, due to its low weight, but also due to its above-described advantageous properties such as the sustainability of the hybrid cord, the low tendency to flat spotting by only low shrinkage properties of the cord and the good connectability of the cord to rubber, the performance of Tire, in particular a UHP (Ultra High Performace) tire, increased. The difference in the fineness between the two yarns should be chosen as small as possible in order to obtain the most uniform / symmetrical cord, which can be processed well and has a good residual strength after fatigue. It is advantageous if both yarns forming the cord have a very similar fineness.

It is advantageous if the two, the hybrid cord forming yarns are twisted end with a rotation of 300-480 t / m. Too high a rotation speed prolongs the manufacturing process, requires more material and increases costs. If the rotation speed is too low, the cord loses its spring-like effect and a sufficient elevation of the green tire would not be guaranteed.

In order to ensure a reliable adhesion of textile reinforcing materials to the rubber, it is expedient to provide the hybrid cords with an adhesive impregnation, for example with an RFL dip in the 1 or 2 bath process. Preferred PES yarns are PET yarns or PEN yarns. Both yarns behave approximately the same, but the PET yarn is cheaper and is therefore preferred.

If one uses at least one of the above-described reinforcement layer in a pneumatic vehicle tire, preferably as a belt bandage, the tire has a particularly good high-speed capability and flattening under load (flat-spotting) are greatly reduced.

When using the above-described reinforcement layer as bead reinforcement in a pneumatic vehicle tire, the advantage lies in the fact that the hybrid-strength support has only a small shrinkage compared with nylon strength supports commonly used and thus the tendency for flat spotting is reduced. Compared to known aramid strength carriers, which are also used in the bead reinforcement, advantages are achieved in particular with regard to the material costs, but sufficient strength is obtained.

Exemplary embodiments and further advantages of the invention are explained in more detail in connection with the following table:

A PET yarn with a fineness of 1440 dtex, Z- twisted with 370 T / m initial twist and a yarn of aramid with a fineness of 1680 dtex, Z- twisted with 370 T / m initial twist, were finished with a final twist of 370 T / m to a hybrid cord (PET 1440x1 + Aramid 1680x1) S-twisted.

Another exemplary hybrid cord which can be used in the reinforcing layer according to the invention is a PET yarn with a fineness of 1100 dtex, Z-twisted with 420 T / m first twist and an aramid yarn with a fineness of 1100 dtex, Z-twisted with 420 T / m initial twist were twisted with a final twist of 420 T / m to a hybrid cord (PET 1110x1 + aramid 1100x1) S-.

Alternatively, the yarns S and the cord Z can be turned. As a comparison to the above-mentioned cord constructions according to the invention, a hybrid cord of aramid and nylon of the construction aramid 1680x1 + PA66 1400x1 is listed. The aramid / PET hybrid cords according to the invention have a much lower shrinkage of about 1.5% to 2.5% than a nylon / aramid hybrid cord with a shrinkage of up to max. 4% (according to ASTM D 855 at 180 ^° C.). Thus, when using the hybrid cords according to the invention as a strength carrier in the belt bandage and / or in the bead reinforcement of a pneumatic vehicle tire, flat spotting is reduced. In addition, the cords according to the invention are less expensive than the comparison cords. The others

Properties of both cords, e.g. the elongation at break, the elongation at a force of 45 N, however, are comparable.

Claims

claims

1. Reinforcing layer for elastomeric products, in particular for the

A belt bandage of pneumatic vehicle tires, said reinforcements being hybrid cords disposed within said ply substantially parallel to each other and constructed of a first twisted yarn of a first material and a second twisted yarn of a second material end-twisted together the first twisted yarn is an aramid yarn, characterized in that the second twisted yarn is a PES yarn.

Second reinforcement layer according to claim 1, characterized in that the aramid yarn has a fineness <1680 dtex.

3. Reinforcing layer according to at least one of the preceding claims, characterized in that the PES yarn has a fineness <1670 dtex.

4. reinforcement layer according to at least one of the preceding claims, characterized in that both yarns are twisted to a hybrid cord with 300-480 t / m.

5. reinforcement layer according to at least one of the preceding claims, characterized in that the hybrid cords are provided with an adhesive impregnation to ensure the adhesion of the reinforcement to the rubber.

6. Reinforcing layer according to at least one of the preceding claims, characterized in that the aramid yarn has a fineness of 1680 dtex and the PES yarn has a fineness of 1440 dtex.

7. reinforcement layer according to at least one of the preceding claims 1-5, characterized in that the aramid yarn has a fineness of 1100 dtex and the PES yarn has a fineness of 1100 dtex.

8. reinforcement layer according to at least one of the preceding claims, characterized in that the PES yarn is a PET yarn.

9. reinforcement layer according to at least one of claims 1-7, characterized in that the PES yarn is a PEN yarn.

10. A pneumatic vehicle tire, comprising at least one reinforcement layer according to at least one of claims 1 to 8 or 1 to 7, 9.

11. Pneumatic vehicle tire according to claim 10, characterized in that the reinforcement layer is arranged as a belt bandage and / or as a bead amplifier.