Reinforcement layer for pneumatic vehicle tyre, preferably for belt ply of pneumatic vehicle tyre

Abstract

The invention relates to a reinforcement layer for a pneumatic vehicle tyre, preferably for a belt ply of a pneumatic vehicle tyre, where the reinforcement layer comprises a reinforcing element having at least one multifilament, and where the at least one multifilament is composed of a polyamide, the majority of which is based on renewable raw materials. For environmental and resource protection, together with good product quality, the multifilament is composed of nylon-4, 10.

Description

TECHNICAL FIELD

[0001] The present invention relates to a reinforcement layer for a belt layer of a belt band of a pneumatic vehicle tire, preferably for a pneumatic vehicle tire, wherein the reinforcement layer has reinforcing elements comprising at least one multifilament, and wherein the at least one multifilament consists of a polyamide based on renewable raw materials. BACKGROUND

[0002] Such a reinforcement layer is known from DE 10 2010 017 786 A1. In order to protect the environment and resources, together with a good product quality, reinforcing elements comprising nylon-10,10 are used in the reinforcement layer. Nylon-10,10 is a polycondensation product of decamethylene-1,10-diamine and decane-1,10-dioic acid, both monomers being obtained from castor oil. Thus, nylon-10,10 is 100% natural-based, renewable raw material and is not based on mineral oil.

[0003] Reinforcement layers for pneumatic vehicle tires and their reinforcing elements are known to the person skilled in the art in a variety of different designs in terms of construction and material.

[0004] In pneumatic vehicle tires, yarns and cords are used as carcass material in the bead region, for the belt layer and as belt band. During production of the tire, the yarns or cords are embedded in a rubber compound in order to enable them to be used as a layer of rubber-processed reinforcing elements in the tire.

[0005] Belted radial tyres for vehicle wheels, in particular for high speed use, are known. In a pneumatic vehicle tyre, generally a non-permeable inner liner, a radial carcass comprising reinforcing elements extending from the crown area of the tyre through the sidewall to the bead area, which is usually anchored by winding of a bead core having high tensile strength, a radially outward rubber tread having profile grooves and, between the rubber tread and the carcass, a belt arranged between the belt and the tread. The belt can have one or more layers, covering at least the belt edges and comprising reinforcing elements in the form of parallel and substantially circumferentially running cords embedded in a rubber compound. In tyre production, the belt is applied in the form of a plurality of layers with reinforcing elements embedded in uncured rubber compound, which are coiled or wound on the belt. The reinforcing elements for this plurality of layers are embedded in rubber, with a succession of substantially parallel reinforcing elements in the form of threads, which have generally been subjected to a pre-treatment by heat means and / or by impregnation in a manner known to the person skilled in the art, in order to better adhere to the embedded rubber, passing in the longitudinal direction through a calender or extruder in order to be wrapped with a rubber compound. During the shaping process of the tyre, carried out with the tyre building apparatus used so far, and the curing process, the tyre generally stretches up to 2% in the shoulder area and up to 4% in the middle area due to bulging, compared to the uncured blank when it is coiled on a flat drum. Therefore, the reinforcing elements used in the belt should advantageously allow this bulging, but equally have suitable shrinkage characteristics during the curing of the tyre to press down at least the edges of the belt.

[0006] The materials used so far for reinforcing elements in the reinforcement layer, in particular in the belt of a pneumatic vehicle tyre, have first of all made use of textile reinforcing elements, mainly (directly) based on fossil raw materials (mineral oil), such as PET (polyethylene terephthalate), aramid and nylon, or hybrid cords made from their yarns. On the other hand, the use of textile reinforcing elements based on non-mineral oil, made from rayon or lyocell, is known. These are synthetic fibres made from natural polymers, i.e. cellulose.

[0007] In order to protect the environment and resources, efforts are being made to reduce the proportion of raw materials based on mineral oil, such as synthetic fibres, in elastomer products. At the same time, however, the required properties from the product are not to be impaired.

[0008] However, the use of natural fibers, such as cotton, in the rubber industry is limited because they do not have a continuous fiber structure and have a highly variable fiber quality. Moreover, the lack of shrinkage characteristics of natural fibers makes them unsuitable for use as reinforcing elements in the belt band of pneumatic vehicle tires.

[0009] Nylon-10,10 can be resource-saving as it is 100% obtainable from natural renewable raw materials, but the properties of reinforcing elements made of nylon-10,10 in the belt band layer of pneumatic vehicle tires need to be improved. Two properties of such reinforcing elements are particularly desirable in this context: first, the polyamide material has such a good extensibility that a favorable high shrinkage can be obtained; second, the modulus should be in a favorably high range.

[0010] Nylon-10,10 with long soft chains in the acid and diamine components has a relatively good extensibility and thus a desirable high shrinkage, but has a relatively unfavorably low modulus.

[0011] Nylon-6,6 with medium chain length in the acid and diamine components likewise still has a good extensibility and thus still a suitable extensibility and a suitable modulus, but it cannot be produced in an environmentally friendly and resource-saving manner.

[0012] Nylon-4,4 has a relatively poor extensibility due to its short chain length in the acid and diamine components and thus an unfavorably low shrinkage, if any, but has a favorably high modulus. SUMMARY

[0013] It is an object of the present invention to provide a reinforcement layer for pneumatic vehicle tires, preferably for the belt band layer of pneumatic vehicle tires, with reinforcing elements, the polyamide multifilaments of which protect the environment and resources and which improve the product in its quality.

[0014] This object is achieved according to the invention, wherein the multifilaments consist of nylon-4,10.

[0015] This provides a partially bio-based multifilament consisting of nylon-4,10. One of the two monomers from which nylon-4,10 is derived is based primarily on renewable raw materials rather than on mineral oil and is thus environmentally friendly and benign in terms of resources.

[0016] Polyamides are polycondensation products formed from dicarboxylic acids and diamines. One economically important dicarboxylic acid is sebacic acid, which is produced, for example, from castor oil obtained from the seeds of castor oil plants. The "10" component of nylon-4,10 is based on sebacic acid.

[0017] The environmentally friendly character is also emphasized in that the castor oil plants grow under conditions in which they do not compete with other useful plants. Furthermore, the nylon-4,10 fibers have a consistent quality compared to natural fibers and can be produced as continuous fibers. Thus, it is possible to ensure consistent product quality and processing reliability.

[0018] The polyamide-4,10 is characterized by a polymer structure which has a good stretchability and a suitably high shrinkage at a suitable modulus. By comparison with other polyamides, the nylon-4,10 is thus a good compromise between shrinkage and modulus, which is particularly suitable for use as a reinforcing element in the belt band layer.

[0019] Furthermore, the low water absorption capacity of the nylon-4,10 is noteworthy, which means that good properties such as the breaking strength are also obtained in the presence of moisture.

[0020] Furthermore, it is advantageous that the nylon-4,10 has a great similarity to the nylon-6,6 which is often used in the reinforcement layer. In this way, it is possible to easily replace the nylon-6,6 (PA 6,6) by the nylon-4,10 (PA 4,10) and to retain, for example, the adhesive system.

[0021] The following table shows the advantageous properties of the PA 4,10 multifilament over the PA 6,6 multifilament.

[0022]

[0023] These values were measured on the yarn without twisting.

[0024] The shrinkage was determined according to ASTM D885 and ASTM D4974.

[0025] The force / elongation data were determined according to ASTM D855M. DETAILED DESCRIPTION

[0026] In one embodiment of the invention, the reinforcing element is an end-twisted cord made of at least two twisted multifilaments. The twisting of the multifilaments or of the cord achieves an improvement in the fatigue resistance of the reinforcing element compared to the reinforcing element without twisting.

[0027] It is appropriate when the multifilaments have a fineness of 100 to 5000 dtex and a twist rate of 100 to 600 t / m. Such multifilaments can be produced in a simple manner and are suitable for use as reinforcing elements in pneumatic vehicle tires.

[0028] It is advantageous when the cord consists of 2 or 3 end-twisted multifilaments.

[0029] In a specific form of the invention, all of the multifilaments of the cord consist of nylon-4,10.

[0030] In an alternative form of the invention, one of the multifilaments of the cord does not consist of nylon-4,10. But it is also possible that at least one of the multifilaments of the cord does not consist of nylon-4,10. In that case, the cord is a so-called hybrid cord. Such a cord is then at least partially based on renewable raw materials, is configured in a resource-saving manner, and as a further advantage, offers the option of a defined adjustment of the cord through the specific material selection of the yarns that are not composed of nylon-4,10.

[0031] The invention likewise relates to a pneumatic vehicle tire having a reinforcement layer according to the above detailed reinforcement layer. Such a reinforcement layer is a belt layer or a bead reinforcement, for example a chipper or a flipper.

[0032] Pneumatic vehicle tires are mass-produced products, wherein the partial replacement of materials based on mineral oil by materials that are not based on mineral oil has a particularly important influence in terms of resource conservation. Furthermore, it has been shown that a reinforcement layer comprising reinforcing elements composed of multifilaments of nylon-4,10 leads to high durability in the tire.

[0033] The automobile tire can for example have a belt layer of a cord having the following construction:

[0034] Variable A: Construction / material: 1400x1 / nylon-4,10

[0035] End twist: 100 t / m

[0036] Variable B: Construction / material: 940x2 / nylon-4,10

[0037] End twist: 350 t / m

[0038] In the case of a cord, i.e. in the case of a reinforcing element having two or more multifilaments, the yarn twist is equivalent to the cord twist, but in the opposite direction.

Claims

1. A reinforcement layer for a pneumatic vehicle tire, preferably for a belt layer of a pneumatic vehicle tire, wherein, The reinforcing layer has reinforcing elements comprising at least one multifilament, and wherein said at least one multifilament consists of a polyamide based mainly on renewable raw materials, characterized in that the multifilament consists of nylon-4,10, the multifilament having a fineness of 100 to 5000 decitex and a twist rate of 100 to 600 t / m.

2. Reinforcing layer according to claim 1, characterized in that The reinforcing elements are end-twisted cords formed of at least two twisted multifilaments.

3. Reinforcing layer according to one of the preceding claims, characterized in that The cord consists of 2 or 3 end-twisted multifilaments.

4. Reinforcing layer according to one of the preceding claims, characterized in that All the multifilaments in the cord consist of nylon-4,10.

5. Reinforcing layer according to claim 3 or 4, characterized in that At least one multifilament in the cord does not consist of nylon-4,10.

6. A pneumatic vehicle tire characterized by, The pneumatic vehicle tire comprises a reinforcing layer as in one of claims 1 to 5.

7. The pneumatic vehicle tire of claim 6, wherein, The reinforcing layer is a belt layer or a bead reinforcement, such as a reinforcing layer or a bead filler.

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