Vehicle pneumatic tire

Abstract

The present invention relates to a vehicle pneumatic tire having a radial structure, the vehicle pneumatic tire having a tread (1), a radial carcass, a cord belt compound (8) having at least two cord belt layers (8a, 8b) and at least one cord belt hoop layer (9) arranged radially outside the cord belt, wherein the cord belt hoop layer comprises cords made of at least two multifilament yarns twisted to each other, the cords being arranged parallel to each other within the cord belt hoop layer (9), and wherein the multifilament yarns are made of recycled polyethylene terephthalate (rPET). The rPET cord (10) has an elongation of 2% to 5% at 20°C under a force of 1.56 cN / dtex and an elongation of 6% to 9% at 120°C; furthermore, the sum of the elongation at break and the heat shrinkage rate determined at 180°C is greater than 17% when the prestress is 0.01 cN / dtex and the duration of action is two minutes; furthermore, the heat shrinkage rate determined at 180°C is greater than 2.5% when the prestress is 0.01 cN / dtex and the duration of action is two minutes.

Description

Technical Field

[0001] The present invention relates to a vehicle pneumatic tire having a radial structure, the vehicle pneumatic tire having a tread, a radial carcass, and a cord belt compound having at least two cord belt layers and at least one cord belt hoop layer disposed radially outside the cord belts, wherein the cord belt hoop layer comprises cords composed of at least two multifilament yarns twisted to each other and arranged parallel to each other within the cord belt hoop layer, and wherein the multifilament yarns are composed of recycled polyethylene terephthalate (rPET). Background Technology

[0002] Such a vehicle pneumatic tire is known from EP 257 62 45B1. Recycled PET (rPET) is not obtained directly from fossil raw materials, but is 100% recycled from used PET products (e.g., PET beverage bottles). Here, the used PET material is cleaned, shredded, and extruded into fibers via melt spinning. These fibers are further processed into multifilament yarns and cords. Reusing used PET materials in the reinforcing components of vehicle pneumatic tires is both environmentally friendly and resource-saving.

[0003] Single-layer or multi-layer cord bands are well known to those skilled in the art.

[0004] It is also known from EP-B-1 671 813 that PET cords with an elastic modulus (measured at 160°C) of not less than 2.5 mN / dtex% under a load of 29.4 N are used in the cord belt layers of pneumatic tires. Furthermore, the cords are treated with a composition that promotes adhesion, comprising a thermoplastic polymer, a thermosetting waterborne polyurethane resin, and an epoxy resin compound. It is also common to use nylon cords, particularly PA 6.6, in the cord belt layers of pneumatic tires. Due to the relatively low tensile modulus of nylon cords, for specific applications (especially where high-speed durability of the tire is important), two cord belt layers with nylon cords as reinforcing members are required. The primary function of the cord belt layers in a tire is to prevent relative movement at the edges of the lateral cord belt layers to avoid edge separation. Summary of the Invention

[0005] The purpose of this invention is to provide an rPET cord for use in (multiple) cord belt layers, which ensures good high-speed durability, long service life and low flat spot effect in tires even when the belt layer may be implemented as a single layer.

[0006] According to the present invention, the proposed objective is achieved by the following means: the rPET cord has an elongation of 2% to 5% at 20°C under a force of 1.56 cN / dtex and an elongation of 6% to 9% at 120°C; the sum of the elongation at break of the rPET cord and the heat shrinkage rate determined at 180°C is greater than 17% when the prestress is 0.01 cN / dtex and the duration of action is two minutes; and the heat shrinkage rate of the rPET cord determined at 180°C is greater than 2.5% when the prestress is 0.01 cN / dtex and the duration of action is two minutes.

[0007] The cord belt layer with rPET cords in vehicle pneumatic tires is environmentally friendly. It effectively prevents the cord belt edges from separating, ensuring good high-speed durability and long service life of the tire, and reducing the flat spot effect.

[0008] Multifilaments made from recycled PET (rPET) typically have a lower modulus than those made from non-recycled PET. Surprisingly, the properties of the rPET cord according to the invention are achieved with a net elongation of 3% to 6%, preferably 3.5% to 5% (the sum of the stretching of the reinforcing members in each oven during the conversion process). Cords made from non-recycled PET, having a lower tensile modulus, withstand a maximum net elongation of 1.5%. The conversion process, which includes stretching the corresponding reinforcing members, is well known to those skilled in the art.

[0009] Several cord parameters are particularly important for achieving these effects. For example, the total number of cord strands is important; the rPET cord according to the invention should have a total number of strands between 500 dtex and 6000 dtex, particularly between 500 dtex and 3500 dtex. Furthermore, the rPET cord should have a cord twist between 150 tpm and 650 tpm, preferably between 200 tpm and 650 tpm.

[0010] The rPET cords according to the invention, arranged in the eccentric layer at 60 epdm to 160 epdm, and especially 80 epdm to 140 epdm, have proven particularly advantageous for preventing edge separation of the cord layer, improving tire high-speed durability, and extending service life. Only a single eccentric layer is required here.

[0011] In another embodiment, the pneumatic tire of the vehicle according to the invention has multiple layers, particularly two layers, of cord bands. Attached Figure Description

[0012] Other features, advantages, and details of the invention will now be described in detail with reference to the accompanying drawings illustrating embodiments. Hereinafter, this single drawing, namely... Figure 1 A cross-section of a vehicle's pneumatic tire is shown schematically.

[0013] List of reference numerals

[0014] 1.......tread

[0015] 2.......sidewall

[0016] 3.......Bead area

[0017] 4....... Tire bead core

[0018] 5. Bead outline

[0019] 6....... Fetal layer

[0020] 7.......Inner layer

[0021] 8....... Cord tape composite

[0022] 8a......cord tape layer

[0023] 8b......cord tape layer

[0024] 9....... Hoop layer

[0025] 10......r PET cord Detailed Implementation

[0026] Figure 1 The illustrated pneumatic tire is a tire of a passenger motor vehicle with a radial structure, and has a tread 1, sidewalls 2, a bead region 3 with a bead core 4 and a bead profile 5, a carcass layer 6 (which surrounds the two bead cores 4), an inner layer 7, and a cord tape compound 8 disposed between the carcass layer 6 and the tread 1. In the illustrated embodiment, the cord tape compound 8 has two cord tape layers 8a and 8b, which can be constructed in a known manner by reinforcing members made of steel cords embedded in a rubber compound, extending parallel to each other. Here, the steel cords in cord tape layer 8a intersect with the steel cords in the other cord tape layer 8b and form an angle with the tire circumferential direction at a common angle on the order of 20° to 35°. A hoop layer 9 (crown layer) is present radially outside the two cord tape layers 8a and 8b. This hoop layer is formed by continuously spirally winding cords 10 made of rPET (recycled polyethylene terephthalate) in the circumferential direction of the tire and covers the lateral edges of the cord tape composite 8.

[0027] According to the present invention, rPET cord 10 with a structure of 1100 dtex × 2, 1440 dtex × 2, 720 dtex × 2, 550 dtex × 2, or 1670 dtex × 2 is used. This cord has the following characteristics: under a force of 1.56 cN / dtex, the expansion of the cord 10 is between 2% and 5% at a temperature of 20°C, and between 6% and 9% at a temperature of 120°C. Under a prestress of 0.01 cN / dtex applied for a period of two minutes at a temperature of 180°C, the sum of the elongation at break and the rate of thermal shrinkage is greater than 17%. Furthermore, under a prestress of 0.01 cN / dtex at 180°C (for a period of two minutes), the rate of thermal shrinkage is greater than 2.5%. The net elongation (the sum of the tensile reinforcement members in each oven during the conversion process) is in the range of 3% to 6%, preferably in the range of 3.5% to 5%.

[0028] The rPET cord 10 according to the invention has a total count between 1100 dtex and 3340 dtex. In particular, the rPET cord 10 is used with a cord twist between 150 and 650 tpm (twist per meter), especially between 200 tpm and 650 tpm.

[0029] The spacing between the windings of the rPET cord 10 to form the cord banding layer is set such that the completed banding layer is between 60 and 160 epdm (number of ends per decimeter). In a preferred embodiment of the invention, the banding layer 9 is between 80 and 140 epdm.

[0030] The high-speed durability of a tire having a single rim layer 9 according to an embodiment of the invention is equivalent to that of a tire having a rim layer with nylon 6.6 as a reinforcing member, as in a known two-layer embodiment. Another advantage of the rim layer according to the invention is its improved robustness to impact loads without the risk of cord breakage in the cord belt layer. Compared to conventionally used nylon cords, the flat spot effect (temporary deformation of the tire's imprint when parked) is significantly reduced in tires according to the invention, and it is more environmentally friendly than conventional cords.

Claims

1. A vehicle pneumatic tire having a radial structure, the vehicle pneumatic tire having a tread (1), a radial carcass, a cord belt compound (8) having at least two cord belt layers (8a, 8b) and at least one cord belt clamp layer (9) disposed radially outside the cord belts, wherein the cord belt clamp layer (9) comprises cords composed of at least two multifilament yarns twisted together, the cords being arranged parallel to each other within the cord belt clamp layer (9), and wherein the multifilament yarns are composed of recycled polyethylene terephthalate (rPET). Its features are, The rPET cord (10) exhibits an elongation of 2% to 5% at 20°C under a force of 1.56 cN / detx, and an elongation of 6% to 9% at 120°C. The sum of the elongation at break of the rPET cord (10) and the heat shrinkage rate determined at 180°C is greater than 17% when the prestress is 0.01 cN / dtex and the duration of action is two minutes. The heat shrinkage rate of the rPET cord (10) at 180°C is greater than 2.5% when the prestress is 0.01 cN / dtex and the duration is two minutes. The net elongation of the rPET cord (10) is in the range of 3% to 6%.

2. The vehicle pneumatic tire according to claim 1, characterized in that, The net elongation of the rPET cord (10) is in the range of 3.5% to 5%.

3. The vehicle pneumatic tire according to claim 1, characterized in that, The rPET cord (10) has a total number of strands between 500 dtex and 6000 dtex.

4. The vehicle pneumatic tire according to claim 3, characterized in that, The rPET cord (10) has a total number of strands between 500 dtex and 3500 dtex.

5. The vehicle pneumatic tire according to claim 1, characterized in that, The rPET cord (10) has a cord twist between 150 tpm and 650 tpm.

6. The vehicle pneumatic tire according to claim 5, characterized in that, The rPET cord (10) has a cord twist between 200 tpm and 650 tpm.

7. The vehicle pneumatic tire according to any one of claims 1 to 6, characterized in that, The rPET cord (10) has the following structure: rPET 550dtex×2, rPET 1100dtex×2, rPET 1440dtex×2, rPET 720dtex×2 or rPET 1670dtex×2.

8. The vehicle pneumatic tire according to any one of claims 1 to 6, characterized in that, The rPET cord (10) is arranged in the cord band layer (9) at a length of 60 epdm to 160 epdm.

9. The vehicle pneumatic tire according to claim 8, characterized in that, The rPET cord (10) is arranged in the cord band layer (9) at a length of 80 epdm to 140 epdm.

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