Vehicle tire with belt bandage

Abstract

To provide a tire for a vehicle including a belt bandage showing further improvement of contraction behavior, especially improvement of high speed behavior.SOLUTION: The present invention relates to a tire for a vehicle, the tire for the vehicle having a belt bandage, where the belt bandage comprises strength members, where the strength members have hybrid cords arranged parallel to one another within the ply, and where the hybrid cords, in any case, contain at least one yarn made of polyethylene terephthalate (PET) and at least one yarn made of polyamide. According to the invention, the PET of the yarn of the hybrid cord of the belt bandage is recycled PET (rPET).SELECTED DRAWING: None

Description

[Technical field]

[0001] The present invention relates to a vehicle tyre having a belt bandage, the belt bandage including strength members having hybrid cords arranged parallel to one another in plies, the hybrid cords including in each case at least one yarn made of polyethylene terephthalate (PET) and at least one yarn made of polyamide, respectively. [Background technology]

[0002] Strength members for reinforcing various elastomeric products are known. It is therefore known that a belt bandage can be used in a pneumatic vehicle tire, the belt bandage being configured with one or more layers and including strength members in the form of cords embedded in rubber, covering the belt edges and extending in a substantially circumferential direction. This belt bandage has the purpose of preventing tire inflation due to centrifugal forces occurring during operation, especially in high speed applications.

[0003] During tire production, the bandage is applied in the form of plies, strips or individual cords with strength members incorporated in the unvulcanized rubber mix that are wound or wound on the bandage. The strength members are embedded in the rubber with essentially parallel sheets of strength members in thread form. The strength members are generally pretreated thermally and / or by impregnation to better adhere to the embedding rubber in a manner known to those skilled in the art, and are passed longitudinally through a calender or extruder to be covered with the rubber mix. During the process of molding and vulcanization of tires with existing equipment, the tire generally expands due to bulging by up to 2% in the shoulder regions and up to 4% in the central region, compared to the unvulcanized green tire when the green tire is wound on a flat drum. With more modern molding drums, it is necessary to further reduce the strain during tire production to about 2% or less. With more modern devices, the bulging is further reduced. A further challenge is the shrinkage behavior of certain cord materials at high temperatures. A lower shrinkage is necessary for a higher dimensional stability of vehicle tires and therefore for a better flat spot behavior. Flat spot behavior (= reversible plastic flattening in the area in contact with the ground when parked) is a term well known to the person skilled in the art.

[0004] The cords of the bandage are intended to allow sufficient expansion during the molding process and to allow accurate shaping of the tire in the vulcanization mold during tire production, and to ensure good high-speed performance during operation after the tire is completed. To meet these requirements, the cords should be stretchable to a strain of about 3% to 4% under moderate forces, and to higher strains only under very strong forces.

[0005] US Patent No. 7,252,129 B2 discloses a hybrid cord made of aramid fibers and additional fibers selected from the group consisting of polyester, nylon, and rayon, which provides relatively small separation of the individual threads of the strength member layers.

[0006] Korean Patent Publication No. 100829260 B1 and KR100829261 describe hybrid cords made of PET (polyethylene terephthalate) and nylon, twisted at the ends at 270-330 t / m (330 turns per meter) and dipped twice. Compared to a once-dipped cord made of nylon, this results in a reduced strain at 45N and a smaller shrinkage at 180°C. No effect on the shrinkage force is clear from these documents.

[0007] Hybrid cords made of polyester and polyamide are also described in WO 2014 / 001039 A1, WO 2015 / 137901 A1 and WO 2017 / 048208 A1.

[0008] WO 2011 / 147635 A1 discloses, inter alia, the use of recycled PET in the carcass ply of vehicle tires. Summary of the Invention [Problem to be solved by the invention]

[0009] The problem addressed by the present invention is that of providing a vehicle tire of the type specified at the beginning, comprising a belt bandage, which exhibits a further improvement in its retraction behavior and therefore in particular in its high-speed behavior, while at the same time being produced as sustainably as possible and which exhibits improved rolling resistance properties. [Means for solving the problem]

[0010] This problem is solved if the PET is recycled PET (rPET).

[0011] Surprisingly, it has been found that by using recycled PET as strength members, a further improvement in the shrink behavior (greater shrinkage) is achieved compared to PET originally produced from crude oil, i.e. non-recycled PET, and an improvement in the properties of the belt bandage of the vehicle tire according to the invention is achieved, i.e. an improvement in the high speed performance of the vehicle tire according to the invention. The possibility of cord compression at the belt edge, if it occurs at all, occurs only to a significantly reduced extent, so that fewer cord breaks occur.

[0012] Furthermore, the use of recycled PET offers ecological and economic advantages: it avoids the production of new (non-renewable) petroleum-based materials, thereby avoiding the over-utilization of finite crude oil resources. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0013] In the context of the present invention, "recycled PET" is understood to mean in particular PET obtained by remelting from post-consumer PET products such as PET bottles or other PET articles, without significant decomposition and restructuring of the polymer. The direct starting material for recycled PET is not crude oil, but bottles or other articles made of PET.

[0014] In the context of the present invention, a cord is a linear construction made of two or more twisted yarns. A hybrid cord is a cord made of two or more different twisted yarns. In the context of the present invention, a yarn is a linear construction made of individual filaments or fibers according to DIN 60900.

[0015] The unit "dtex" is well known to those skilled in the art and is a measure of weight per unit length.

[0016] The lower the fineness dtex, the lighter the corresponding yarn or cord.

[0017] In an advantageous embodiment of the invention, the yarn made from recycled PET has a fineness between 200 and 1670 dtex, preferably between 200 and 1350 dtex.

[0018] Such a fineness of the yarns made of recycled PET in the hybrid cords in the belt bandage of the tire according to the invention achieves particularly good high speed performance while at the same time reducing the weight and therefore improving the rolling resistance.

[0019] In an advantageous embodiment of the invention, the polyamide yarn has a fineness between 200 and 1400 dtex, preferably between 200 and 1000 dtex.

[0020] Such fineness of the polyamide yarns in the hybrid cords in the belt bandages of the tires according to the invention also achieves particularly good high speed performance while reducing the weight and therefore improving the rolling resistance, especially compared to cords made of 100% by weight nylon.

[0021] In an advantageous embodiment of the invention, the hybrid cord of the belt bandage has an overall fineness (overall fineness) of 400 to 3100 dtex, preferably 400 to 2900 dtex, particularly preferably 400 to 2200 dtex.

[0022] Such an overall fineness of the hybrid cords in the belt bandage of the tire according to the invention achieves particularly good high speed performance while at the same time reducing the weight and therefore improving the rolling resistance.

[0023] In an advantageous embodiment of the invention, the recycled PET yarn and the polyamide yarn are twisted at the ends to form a hybrid cord of 200-700 t / m, preferably 300-600 t / m, which gives a very good fatigue resistance and therefore a very good durability to the tire.

[0024] In a preferred embodiment, the thread density of the cord of the belt bandage is 50 to 150 epdm, and particularly preferably 50 to 120 epdm. This density ensures sufficient strength when used in a pneumatic tire.

[0025] According to the invention, the use of rPET and polyamide in the belt bandage allows to reduce the number of cords based on the tire width (epdm (ends per decimeter) = ends per decimeter) and / or ply thickness, which is further accompanied by advantages in rolling resistance. At the same time, this achieves a higher dimensional stability and therefore improves flat spot behavior.

[0026] In a particularly advantageous embodiment of the invention, the recycled PET yarn has a fineness of 1000-1200 dtex and the polyamide yarn has a fineness of 900-1000 dtex, which achieves particularly good properties for solving the problem addressed by the invention, as is evident from Table 1 below.

[0027] Herein, the recycled PET yarn and the polyamide yarn are preferably twisted at the ends to form a hybrid cord of 300-380 t / m, which achieves very good fatigue resistance.

[0028] Herein, the thread density of the cord in the belt bandage is preferably 50 to 150 epdm, particularly preferably 70 to 120 epdm.

[0029] Adapting the thread density of the cord to the fineness achieves the technical objectives, in particular optimum properties in terms of high speed performance, dimensional stability and therefore flat spot behavior and rolling resistance behavior.

[0030] In a further particularly advantageous embodiment of the invention, the yarns made from recycled PET have a fineness between 200 and 360 dtex and the yarns made from polyamide have a fineness between 200 and 360 dtex, which achieves particularly good properties for solving the problem addressed by the invention, as is evident from table 2 below. These finenesses simultaneously achieve particularly very thin plies in the belt bandage of the vehicle tire according to the invention, which further optimizes the rolling resistance behavior.

[0031] Herein, the recycled PET yarn and the polyamide yarn are preferably twisted at the ends to form a hybrid cord of 500-600 t / m, which achieves very good fatigue resistance.

[0032] Herein, the thread density of the cord in the belt bandage is preferably 100 to 150 epdm, particularly preferably 110 to 130 epdm.

[0033] Adapting the thread density of the cord to the fineness achieves the technical objectives, in particular optimum properties in terms of high speed performance, dimensional stability and therefore flat spot behavior and rolling resistance behavior.

[0034] In a further particularly advantageous embodiment of the invention, the yarns made from recycled PET have a fineness between 700 and 800 dtex and the yarns made from polyamide have a fineness between 680 and 780 dtex, which achieves particularly good properties for solving the problem addressed by the invention. These finenesses also make it possible to make the plies thinner in the belt bandage of the vehicle tire according to the invention, in particular in comparison with cords made from 100% by weight of nylon, which further optimizes the rolling resistance behavior.

[0035] Herein, the recycled PET yarn and the polyamide yarn are preferably twisted at the ends to form a hybrid cord of 350-450 t / m, which achieves very good fatigue resistance.

[0036] Herein, the thread density of the cord in the belt bandage is preferably 50-80 epdm.

[0037] Adapting the thread density of the cord to the fineness achieves the technical objectives, in particular optimum properties in terms of high speed performance, dimensional stability and therefore flat spot behavior and rolling resistance behavior.

[0038] In a further particularly advantageous embodiment of the invention, the yarns made from recycled PET have a fineness of 500-600 dtex and the yarns made from polyamide have a fineness of 430-530 dtex, which achieves particularly good properties for solving the problem addressed by the invention. These finenesses also make it possible to make the plies thinner in the belt bandage of the vehicle tire according to the invention, in particular in comparison with cords made from 100% by weight of nylon, which further optimizes the rolling resistance behavior and achieves high dimensional stability.

[0039] Herein, the recycled PET yarn and the polyamide yarn are preferably twisted at the ends to form a hybrid cord of 400-500 t / m, which achieves very good fatigue resistance.

[0040] Herein, the thread density of the cord in the belt bandage is preferably 70-100 epdm.

[0041] Adapting the thread density of the cord to the fineness achieves the technical objectives, in particular optimum properties in terms of high speed performance, dimensional stability and therefore flat spot behavior and rolling resistance behavior.

[0042] The polyamide of the polyamide yarn is selected from the group consisting of polyamide 6 (PA 6), polyamide 66 (PA 66), polyamide 12 (PA 12), polyamide 11 (PA 11), polyamide 1313 (PA 1313), polyamide 4 (PA 4), polyamide 7 (PA 7), polyamide 8 (PA 8), polyamide 9 (PA 9), polyamide 46 (PA 46), polyamide 610 (PA 610), polyamide 612 (PA 612), polyamide 69 (PA 69) and polyamide 66 / 6 (PA 66 / 6).

[0043] The use of PA 6 and / or PA 66 is preferred, and the use of PA 66 (nylon) is particularly preferred.

[0044] The use of PA 66 as material for the polyamide yarns gives particularly good properties with regard to the tasks addressed.

[0045] In an advantageous embodiment of the invention, the weight fraction of recycled PET in the hybrid cord is between 40% and 60%, thereby providing an optimal solution to the problem addressed by the invention, the hybrid cord containing a significant proportion of sustainable material in the form of recycled PET.

[0046] To ensure reliable adhesion of the textile strength members to the rubber, it is advantageous to impregnate the hybrid cord with an adhesive. This adhesive impregnation may be carried out, for example, by RFL immersion (resorcinol-formaldehyde-latex) in a one-bath or two-bath process. However, any further process and adhesive known to the skilled person for impregnation is also conceivable, for example in particular resorcinol- and formaldehyde-free immersion.

[0047] In addition to this, further and conventional pretreatment processes well known to those skilled in the art may also be carried out, such as, in particular, hot drawing of the cord.

[0048] The belt bandage is preferably configured as a single-ply or multi-ply bandage at an angle of 0° to 5° with respect to the circumferential direction, with single-ply bandages being particularly preferred. In this respect, "configured" is understood to mean that the bandage is wound in the circumferential direction in a single-ply or multi-ply fashion, preferably in a single-ply fashion.

[0049] The recycled PET yarns may be twisted in the S or Z direction.

[0050] The polyamide yarns may be twisted in the S or Z direction.

[0051] The yarns advantageously have the same twist direction, and therefore are preferably both twisted in either the S-direction or the Z-direction.

[0052] The twist direction to form the hybrid cord is advantageously opposite to the yarn twist direction, which results in improved and more consistent quality production in terms of strength of the cord and hence the belt bandage. The present invention also includes the following items. [Item 1] A vehicle tire including a belt bandage, the belt bandage including strength members, the strength members including hybrid cords arranged parallel to one another within the plies, each of the hybrid cords including at least one yarn made of polyethylene terephthalate (PET) and at least one yarn made of polyamide, the PET being recycled PET (rPET), Vehicle tires. [Item 2] 2. The vehicle tire according to item 1, wherein the yarn made of recycled PET has a fineness of 200 to 1670 dtex, preferably 200 to 1350 dtex. [Item 3] 3. The vehicle tire according to item 1 or 2, wherein the polyamide yarn has a fineness of 200 to 1400 dtex, preferably 200 to 1000 dtex. [Item 4] The vehicle tire according to any one of items 1 to 3, wherein the hybrid cord as a whole has a fineness of 400 to 3100 dtex, preferably 400 to 2900 dtex, and particularly preferably 400 to 2200 dtex. [Item 5] The vehicle tire according to any one of items 1 to 4, characterized in that the yarn made of recycled PET and the yarn made of polyamide are twisted together at their ends to form the hybrid cord of 200 to 700 t / m, preferably 300 to 600 t / m. [Item 6] 6. The vehicle tire according to any one of items 1 to 5, wherein the yarn made of recycled PET has a fineness of 1000 to 1200 dtex, and the yarn made of polyamide has a fineness of 900 to 1000 dtex. [Item 7] 7. The vehicle tire according to item 6, wherein the yarn made of recycled PET and the yarn made of polyamide are twisted together at their ends to form the hybrid cord of 300 to 380 t / m. [Item 8] 6. The vehicle tire according to any one of items 1 to 5, wherein the yarn made of recycled PET has a fineness of 200 to 360 dtex, and the yarn made of polyamide has a fineness of 200 to 360 dtex. [Item 9] 9. The vehicle tire according to any one of items 1 to 8, wherein the polyamide is polyamide 66 (PA 66). [Item 10] 10. The vehicle tire according to any one of items 1 to 9, wherein a weight percentage of the recycled PET in the hybrid cord is 40 to 60%. EXAMPLES

[0053] The embodiments and further advantages of the present invention will be more specifically described with reference to Tables 1 and 2 below.

[0054] The embodiment of the invention is marked with the letter "E" and is an exemplary and particularly advantageous construction of a hybrid cord for a belt bandage of a vehicle tire according to the invention.

[0055] Controls included a nylon cord typically used in vehicle tire belt bandages, and a hybrid cord made from virgin PET and PA 6.6.

[0056] The measurements were carried out according to the following method. · Breaking force and elongation at break, force and tensile strength (strain 4% and 6%), strain at 45N, shrinkage at 180°C and shrinkage force according to ASTM D 855.

[0057] The properties reported in N / dm each relate to the property measured on the cord, respectively extrapolated over the possible number of cords in the belt bandage per unit tire width (epdm = ends per decimeter), also specified in the table.

[0058] [Table 1]

[0059] Table 1 shows that the hybrid cord made of recycled PET and polyamide in the belt bandage (E1) presented by the present invention surprisingly exhibits a higher shrinkage than the cord made of PA 66 and non-recycled PET (Control 2). Surprisingly, the significant improvement in the shrinkage behavior of the hybrid cord in the belt bandage leads to an improvement in the high-speed performance of the vehicle tire. The possibility of cord compression at the belt edge occurs, if at all, only to a significantly reduced extent, resulting in fewer cord breaks.

[0060] Compared to the standard nylon cord of the prior art belt bandage (Control 1), greater force and tensile strength are seen at 4% and 6% strain.

[0061] Therefore, smaller diameter (relative to the tire width) and fewer strength members may be used in the belt bandage. Starting with 110 epdm for standard cords made of nylon, as shown in Table 1, hybrid cords made of PET and nylon make it possible to reduce the number and achieve the above-mentioned improvement in properties despite the reduced epdm, for example at 80 epdm.

[0062] The reduced number of cords allows the individual cords to be spaced farther apart within the belt bandage, which reduces shear stress on the surrounding rubber matrix, which in turn improves durability.

[0063] At the same time, this results in less shrinkage material being placed within the tire overall, leading to improved flat spot behavior and therefore improved dimensional stability.

[0064] The smaller diameter cords compared to Control 1 allow the belt bandage to be made thinner overall and less rubber mix is ​​required, which improves the rolling resistance behavior of the tire according to the invention.

[0065] The fineness and therefore the weight per unit length of the hybrid cord is also reduced: Control 1 has a total fineness of 2800 dtex, while said fineness is 2040 dtex for the exemplary construction with PET and nylon. The weight savings improve the rolling resistance behavior of the tire according to the invention.

[0066] The benefits resulting from reduced weight, reduced number, and reduced diameter apply to non-recycled and recycled PET, however, the improved shrinkage and associated benefits discussed above are only achieved with recycled PET (the present invention).

[0067] E2 is a further embodiment of the invention, also having a significantly lower fineness and the associated advantages in terms of rolling resistance. As is evident from Table 2, E2 also achieves the advantages as described for E1 compared to the respective controls.

[0068] This construction therefore also improves the properties of contraction and tensile strength which are important for belt bandages.

[0069] Therefore, the use of recycled PET is environmentally friendly and resource efficient. Moreover, recycled PET has a uniform quality similar to PET obtained directly from fossil raw materials. Therefore, a consistent product quality can be guaranteed.

[0070] In a further exemplary embodiment, the hybrid cord made of recycled PET and polyamide in the belt bandage presented by the present invention has the following structure: E3: Hybrid cord rPET 720x1 / PA 66 700x1, 400t / m end twisted, 60epdm E4: Hybrid cord rPET 550x1 / PA 66 470x1, 470t / m end twisted, 80epdm.

[0071] In both E3 and E4, each individual yarn is twisted in the Z direction, and each of the two hybrid cords is twisted in the S direction.

[0072] [Table 2]

Claims

1. 1. A vehicle tire including a belt bandage, the belt bandage including strength members, the strength members including hybrid cords arranged parallel to one another within the plies, each of the hybrid cords including at least one yarn of polyethylene terephthalate (PET) and at least one yarn of polyamide, the PET being recycled PET (rPET); The yarn made of recycled PET has a fineness of 200 to 1670 dtex; said polyamide yarn having a fineness of 900 to 1000 dtex; The hybrid cord as a whole has a fineness of 400 to 2900 dtex, The cord of the belt bandage has a thread density of 50 to 120 epdm; A vehicle tire, characterized in that the yarn made of recycled PET and the yarn made of polyamide are twisted together at their ends to form the hybrid cord of 200 to 700 t / m.

2. A vehicle tire including a belt bandage, the belt bandage including strength members, the strength members including hybrid cords arranged parallel to one another within the plies, each of the hybrid cords including at least one yarn of polyethylene terephthalate (PET) and at least one yarn of polyamide, the PET being recycled PET (rPET), The yarn made of recycled PET has a fineness of 200 to 1670 dtex; said polyamide yarn having a fineness of 200 to 360 dtex; The hybrid cord as a whole has a fineness of 400 to 2900 dtex, The cord of the belt bandage has a thread density of 50 to 120 epdm; A vehicle tire, characterized in that the yarn made of recycled PET and the yarn made of polyamide are twisted together at their ends to form the hybrid cord of 200 to 700 t / m.

3. Vehicle tire according to claim 1 or 2, characterized in that the yarn made of recycled PET has a fineness of between 200 and 1350 dtex.

4. 4. Vehicle tire according to claim 1, characterized in that the hybrid cord as a whole has a fineness of 400 to 2200 dtex.

5. Vehicle tire according to any one of claims 1 to 4, characterized in that the yarns made of recycled PET and the yarns made of polyamide are twisted together at their ends to form the hybrid cord of 300 to 600 t / m.

6. Vehicle tyre according to claim 1, characterized in that the yarns made of recycled PET have a fineness between 1000 and 1200 dtex and the yarns made of polyamide have a fineness between 900 and 1000 dtex.

7. Vehicle tire according to claim 6, characterized in that the yarns made of recycled PET and the yarns made of polyamide are twisted together at their ends to form the hybrid cord of 300 to 380 t / m.

8. Vehicle tyre according to claim 2, characterized in that the yarns made of recycled PET have a fineness between 200 and 360 dtex and the yarns made of polyamide have a fineness between 200 and 360 dtex.

9. Vehicle tire according to any one of the preceding claims, characterized in that the polyamide is polyamide 66 (PA 66).

10. The vehicle tire according to any one of claims 1 to 9, characterized in that a weight percentage of the recycled PET in the hybrid cord is 40 to 60%.

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