Tire cord

Abstract

The present disclosure relates to a tire cord. The tire cord includes a polyester stretch yarn containing recycled polyethylene terephthalate. The tire cord can exhibit excellent physical properties desired by the industry while containing an eco-friendly material.

Description

Technical Field

[0001] This disclosure relates to a tire cord comprising a drawn polyester filament containing recycled polyethylene terephthalate. Background Technology

[0002] With the gradual improvement of vehicle performance and road conditions, there is a need to maintain tire stability and durability during high-speed driving. Furthermore, considering environmental, energy, and fuel efficiency issues, lightweight tires with excellent durability are required. As one way to meet these requirements, tire cords, used as rubber reinforcing materials for tires, are being actively researched.

[0003] Tire cords can be classified according to the components and functions in which they are used. For example, they can be divided into the tire carcass, which provides complete tire support; the belt ply, which supports the load and prevents deformation at high speeds; and the crown belt ply, which prevents deformation of the belt ply (see...). Figure 1 ).

[0004] Meanwhile, many countries, including the European Union, are strengthening environmental regulations and mandating the use of recycled materials in automotive products. Therefore, methods have been explored for using recycled plastics (e.g., polyethylene terephthalate) discarded after being used as plastic containers or fibers in the manufacture of vehicle products.

[0005] However, recycled plastics have poor physical properties compared to virgin plastic materials, and the degradation of physical properties due to thermal decomposition during processing is inevitable.

[0006] Therefore, there is a need for a method that can overcome the limitations of the physical properties of recycled plastics while being eco-friendly in its use. Summary of the Invention

[0007] Technical issues

[0008] In this disclosure, a tire cord is provided comprising polyester drawn yarn containing recycled polyethylene terephthalate.

[0009] Additionally, a tire including the aforementioned tire cords is provided.

[0010] Technical solution

[0011] According to one embodiment of this disclosure, a tire cord is provided comprising a drawn polyester filament containing more than 25% by weight of recycled polyethylene terephthalate, the recycled polyethylene terephthalate having an intrinsic viscosity of less than 1.5 dl / g and an isophthalic acid content of less than 1.0 mol% based on total carboxylic acid composition.

[0012] When measured according to the standard test method of ASTM D 885, the tensile strength is 7.0 g / d to 8.0 g / d, and the elongation at break is 15.0% to 17.5%.

[0013] According to another embodiment of this disclosure, a tire including the aforementioned tire cords is provided.

[0014] The tire cords and the tire including them will be described in more detail below according to embodiments of this disclosure.

[0015] Unless otherwise defined herein, all technical and scientific terms have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains. The terminology used in this disclosure is for the purpose of effectively describing particular embodiments only and is not intended to limit the invention.

[0016] Unless they are expressed differently in the context, the singular expressions of this disclosure may include plural expressions.

[0017] The terms “comprising” and “including” used in this disclosure are used to specify certain features, regions, integers, steps, operations, elements and / or components, which do not exclude the presence or addition of other features, regions, integers, steps, operations, elements, components and / or groups.

[0018] Because the present invention can be modified and has various forms, specific embodiments thereof are shown by way of examples and will be described in detail. However, the present invention is not intended to be limited to the specific forms disclosed, and it should be understood that the present invention includes all modifications, equivalents, and substitutions within the concept and scope of the invention.

[0019] In this disclosure, when terms such as “on top of,” “above,” “below,” and “next” are used to describe the positional relationship between two components, one or more components may be located between the two components unless these terms are used in conjunction with the terms “immediately” or “directly.”

[0020] In this disclosure, when terms such as “after,” “constantly,” “immediately following,” and “before” are used to describe temporal relationships, discontinuous situations may be included unless these terms are used in conjunction with the terms “immediately” or “directly.”

[0021] In this disclosure, the term "at least one" should be understood to include all combinations that can be presented from one or more related items.

[0022] In this disclosure, the terms "recycled polyethylene terephthalate", "recycled PET", or "r-PET" refer to PET resin that is recycled after being used for its original purpose, such as various containers, films, sheets, fibers, etc., in order to reuse waste polyethylene terephthalate (PET).

[0023] In this disclosure, the terms “virgin polyethylene terephthalate”, “virgin PET”, or “v-PET” are used to distinguish recycled polyethylene terephthalate, recycled PET, or r-PET, referring to virgin PET resin that has not been recycled for the manufacture of various containers, films, sheets, fibers, etc.

[0024] In this disclosure, the term "initial twisted yarn" refers to a single strand of yarn made by twisting a filament in either direction.

[0025] In this disclosure, the term "ply yarn" refers to yarn made by twisting two or more untwisted yarns together in either direction, also known as "original cord yarn".

[0026] In this disclosure, the term "tire cord" refers to a plied yarn containing an adhesive, which makes it suitable for direct application to a tire, and is also known as "rubber-impregnated cord".

[0027] Yarns used for tire cords made from recycled PET often struggle to achieve high strength. One reason for this may be the low intrinsic viscosity of recycled PET. Low intrinsic viscosity makes it difficult to orient the polymer during yarn manufacturing. Consequently, it becomes challenging to apply sufficient spinning tension to the yarn, resulting in limited strength.

[0028] Due to supply and cost considerations, recycled PET is primarily derived from waste PET bottles. However, PET bottles contain isophthalic acid, which imparts high flexibility, and a significant amount of catalyst, which enhances reactivity. The additives such as isophthalic acid and catalysts in recycled PET can act as defects in the manufacture of tire cord yarns. This is because, when manufacturing yarns for tire cords that require high-speed spinning methods to achieve high tensile strength, the additives may interfere with the axial orientation of the yarn.

[0029] However, as a result of the inventors’ continued research, it has been discovered that eco-friendly tire cords with excellent physical properties can be provided by using polyester drawn yarns obtained by controlling the intrinsic viscosity and isophthalic acid content of recycled PET.

[0030] According to one embodiment of this disclosure, a tire cord is provided comprising a drawn polyester filament containing more than 25% by weight of recycled polyethylene terephthalate, the recycled polyethylene terephthalate having an intrinsic viscosity of 0.9 dl / g to 1.5 dl / g and an isophthalic acid content of less than 1.0 mol% based on total carboxylic acid composition.

[0031] When measured according to the standard test method of ASTM D 885, the tensile strength is 7.0 g / d to 8.0 g / d, and the elongation at break is 15.0% to 17.5%.

[0032] In melt spinning for yarn production, the process of melting the raw materials at a temperature equal to or above their melting point is performed first. However, raw materials with high crystallinity have high melting points, therefore, the melt spinning process temperature must be increased. This increase in process temperature leads to the problem of thermal decomposition of the raw materials, and results in the deterioration of the physical properties of the yarn and increased costs, such as increased energy consumption or equipment upgrades. In particular, recycled PET is often processed by melting waste PET during the recycling process; therefore, the above problems may be exacerbated when melt spinning is performed using recycled PET.

[0033] However, when using recycled PET with an intrinsic viscosity of 0.9 dl / g to 1.5 dl / g and an isophthalic acid content of less than 1.0 mol% based on the total carboxylic acid composition, the crystallinity of the recycled PET can be controlled below an appropriate level, thus avoiding the aforementioned problems. In other words, when using recycled PET with its intrinsic viscosity and isophthalic acid content controlled within the above range, eco-friendly tire cords with excellent physical properties can be provided.

[0034] In one instance, based on the total dicarboxylic acid component contained in the recycled PET, the recycled PET may have an isophthalic acid content of less than 1.0 mol%, less than 0.95 mol%, less than 0.9 mol%, less than 0.85 mol%, or less than 0.8 mol%.

[0035] Preferably, based on the total dicarboxylic acid component contained in the recycled PET, the recycled PET may have a content of 0 mol% or more and less than 1.0 mol%, 0 mol% to 0.95 mol%, 0 mol% to 0.9 mol%, 0 mol% to 0.85 mol%, 0 mol% to 0.8 mol%, 0.1 mol% or more and less than 1.0 mol%, 0.1 mol% to 0.95 mol%, 0.1 mol% to 0.9 mol%, 0.1 mol% to 0.85 mol%, 0.1 mol% to 0.0 mol%, or 0.1 mol% to 0.95 mol%. The content of isophthalic acid is 0.8 mol%, more than 0.25 mol% and less than 1.0 mol%, 0.25 mol% to 0.95 mol%, 0.25 mol% to 0.9 mol%, 0.25 mol% to 0.85 mol%, 0.25 mol% to 0.8 mol%, more than 0.5 mol% and less than 1.0 mol%, 0.5 mol% to 0.95 mol%, 0.5 mol% to 0.9 mol%, 0.5 mol% to 0.85 mol%, or 0.5 mol% to 0.8 mol%.

[0036] Furthermore, based on the total dicarboxylic acid component contained in the recycled PET, the recycled PET can have the following compositions: greater than 99.0 mol% and less than 100.0 mol%, 99.05 mol% to 100.0 mol%, 99.10 mol% to 100.0 mol%, 99.15 mol% to 100.0 mol%, 99.20 mol% to 100 mol%, greater than 99.0 mol% and less than 99.9 mol%, 99.05 mol% to 99.9 mol%, 99.10 mol% to 99.9 mol%, 99.15 mol% to 99.9 mol%, and 99.20 mol%. Terephthalic acid content up to 99.99 mol%, greater than 99.0 mol% and less than 99.75 mol%, 99.05 mol% to 99.75 mol%, 99.10 mol% to 99.75 mol%, 99.15 mol% to 99.75 mol%, 99.20 mol% to 99.75 mol%, greater than 99.0 mol% and less than 99.50 mol%, 99.05 mol% to 99.50 mol%, 99.10 mol% to 99.50 mol%, 99.15 mol% to 99.50 mol%, or 99.20 mol% to 99.50 mol%.

[0037] In this article, isophthalic acid content and terephthalic acid content refer to the content of isophthalic acid, terephthalic acid, or units derived therefrom in the total dicarboxylic acid or dicarboxylic acid contained in recycled PET. The isophthalic acid content and terephthalic acid content can be determined by calculating the peak intensity of a predetermined proton using NMR measurements of the recycled PET, and then calculating the content (mol%) of the isophthalic acid component and the terephthalic acid component in 100 mol% of the dicarboxylic acid component.

[0038] In another example, the intrinsic viscosity of recycled PET can be from 0.9 dl / g to 1.5 dl / g. As demonstrated by the example below, when the intrinsic viscosity of recycled PET is less than 0.9 dl / g, tensile strength and elongation at break may not be adequately guaranteed in polyester filaments and tire cords containing recycled PET. However, when the intrinsic viscosity of recycled PET exceeds 1.5 dl / g, the high viscosity reduces polymer flowability during the manufacturing process of polyester filaments and tire cords, thus increasing encapsulation pressure and potentially causing encapsulation leakage, resulting in significant fluffing and frequent breakage.

[0039] Specifically, recycled PET can have an intrinsic viscosity of 0.9 dl / g or higher, 0.95 dl / g or higher, or 1.0 dl / g or higher. Furthermore, recycled PET can have an intrinsic viscosity of 1.5 dl / g or lower, 1.45 dl / g or lower, 1.4 dl / g or lower, 1.35 dl / g or lower, 1.3 dl / g or lower, 1.25 dl / g or lower, or 1.2 dl / g or lower.

[0040] Preferably, the recycled PET may have a content of 0.90 dl / g to 1.45 dl / g, 0.90 dl / g to 1.40 dl / g, 0.90 dl / g to 1.35 dl / g, 0.90 dl / g to 1.30 dl / g, 0.90 dl / g to 1.25 dl / g, 0.90 dl / g to 1.20 dl / g, 0.95 dl / g to 1.50 dl / g, 0.95 dl / g to 1.45 dl / g, 0.95 dl / g to 1.40 dl / g, or 0.95 dl / g to 1.35 dl / g. Intrinsic viscosity in dl / g, 0.95dl / g to 1.30dl / g, 0.95dl / g to 1.25dl / g, 0.95dl / g to 1.20dl / g, 1.00dl / g to 1.50dl / g, 1.00dl / g to 1.45dl / g, 1.00dl / g to 1.40dl / g, 1.00dl / g to 1.35dl / g, 1.00dl / g to 1.30dl / g, 1.00dl / g to 1.25dl / g, or 1.00dl / g to 1.20dl / g.

[0041] The intrinsic viscosity can be measured using an Ubbelohde viscometer and a getter, or by dissolving the resin to be measured in an organic solvent to prepare a sample solution and then using an automatic viscometer.

[0042] The content of recycled PET included in the polyester drawn yarn is preferably 25% by weight or more, 25% by weight to 100% by weight, or 30% by weight to 100% by weight. That is, from the perspective of environmental protection and resource recycling, recycled PET is preferably included in the polyester drawn yarn in an amount of 25% by weight or more or 30% by weight or more.

[0043] Optionally, the content of recycled PET can be adjusted according to the recycling method of the recycled PET from which it originates.

[0044] For example, when the recycled PET comes from a chemical recycling method, the content of recycled PET included in the polyester drawn yarn can be from 25% to 100% by weight or from 30% to 100% by weight. Chemically recycled PET is obtained by altering the chemical structure of waste PET through depolymerization, hydrolysis, repolymerization, etc., and exhibits relatively excellent and stable physical properties. Therefore, chemically recycled PET can be included in polyester drawn yarn in amounts up to 100% by weight.

[0045] As another example, when the recycled PET comes from a physical recycling method, the content of recycled PET included in the polyester drawn yarn can be from 25% to 95% by weight or from 30% to 90% by weight. Physically recycled PET is obtained by recycling, color sorting, crushing, washing, and drying waste PET into sheets, and has relatively varied physical properties. During processing using physically recycled PET as a raw material, the degradation of physical properties due to thermal decomposition needs to be considered. Therefore, physically recycled PET can be included in the polyester drawn yarn in amounts of 95% by weight or less or 90% by weight or less.

[0046] In one example, the polyester drawn yarn may comprise virgin PET and recycled PET. Preferably, the polyester drawn yarn may comprise recycled PET within the aforementioned content range and a residual amount of virgin PET. The virgin PET may not contain isophthalic acid or units derived therefrom.

[0047] Preferably, the raw PET can have an intrinsic viscosity of 0.8 dl / g to 1.4 dl / g to prevent excessive fluffing and breakage while ensuring sufficient tensile strength and elongation at break in polyester filaments and tire cords.

[0048] Specifically, the raw PET can have an intrinsic viscosity of 0.8 dl / g or higher, 0.85 dl / g or higher, 0.9 dl / g or higher, 0.95 dl / g or higher, or 1.0 dl / g or higher. Alternatively, the raw PET can have an intrinsic viscosity of 1.4 dl / g or lower, 1.35 dl / g or lower, 1.3 dl / g or lower, or 1.25 dl / g or lower.

[0049] More preferably, the original PET may have an intrinsic viscosity of 0.8 dl / g to 1.4 dl / g, 0.85 dl / g to 1.4 dl / g, 0.85 dl / g to 1.35 dl / g, 0.9 dl / g to 1.35 dl / g, 0.9 dl / g to 1.3 dl / g, 0.95 dl / g to 1.3 dl / g, 0.95 dl / g to 1.25 dl / g, or 1.0 dl / g to 1.25 dl / g.

[0050] Meanwhile, the polyester drawn yarn included in the tire cord can have a suitable fineness within a range that satisfies the physical properties according to this disclosure. For example, the polyester drawn yarn can have a single-ply yarn fineness of 2 denier to 15 denier and a total fineness of 500 denier to 3000 denier.

[0051] Tire cord comprises a raw cord made by twisting two or more strands of drawn polyester filaments together in any direction, and an adhesive attached to the raw cord.

[0052] Preferably, the tire cord may include raw cord having a total fineness of 1,000 denier to 9,000 denier, 1,000 denier to 8,000 denier, 1,000 denier to 7,000 denier, or 1,000 denier to 6,000 denier.

[0053] Preferably, the tire cord can be a biply yarn comprising polyester drawn yarn. As a non-limiting example, by biply twisting polyester drawn yarn having a fineness of 500 to 3000 denier, the original cord can have a total fineness of 1000 to 6000 denier.

[0054] By incorporating recycled PET, tire cord can exhibit superior performance in terms of its contribution to environmental protection. Furthermore, tire cord comprises polyester drawn yarns containing recycled PET with intrinsic viscosity and isophthalic acid content within the aforementioned range, thereby exhibiting the same level of mechanical properties and dimensional stability as tire cord obtained using only virgin PET.

[0055] In one instance, tire cords can exhibit tensile strengths of 7.0 g / d to 8.0 g / d and elongation at break of 15.0% to 17.5% when measured according to the ASTM D 885 standard test method.

[0056] Specifically, tire cords may have tensile strengths of 7.0 g / d or higher, 7.1 g / d or higher, or 7.2 g / d or higher; and less than 8.0 g / d, less than 7.95 g / d, or less than 7.9 g / d.

[0057] In addition, tire cords may have an elongation at break of 15.0% or more, 15.1% or more, 15.2% or more, 15.3% or more, 15.4% or more, or 15.5% or more; and an elongation at break of 17.5% or less, 17.2% or less, 17.0% or less, 16.9% or less, 16.8% or less, 16.7% or less, or 16.6% or less.

[0058] Preferably, the tire cord may have a tensile strength of 7.1 g / d to 8.0 g / d, 7.1 g / d to 7.95 g / d, 7.2 g / d to 7.95 g / d, or 7.2 g / d to 7.9 g / d; and an elongation at break of 15.1% to 17.5%, 15.1% to 17.2%, 15.2% to 17.2%, 15.2% to 17.0%, 15.3% to 17.0%, 15.3% to 16.9%, 15.4% to 16.9%, 15.4% to 16.8%, 15.5% to 16.8%, 15.5% to 16.7%, or 15.5% to 16.6%.

[0059] Tensile strength and elongation at break can be measured using a general-purpose tester according to the ASTM D 885 standard test method.

[0060] In one instance, tire cords can exhibit elongation of 3.5% to 5.0% under a specific load when measured according to the ASTM D 885 standard test method under a load of 4.5 g / d. Elongation at a specific load refers to the elongation at a load of 4.5 g / d in the stress-strain curve obtained when measuring tensile strength and elongation at break.

[0061] Specifically, the tire cords may have an elongation of more than 3.5% or more than 4.0% and less than 5.0% or less than 4.5% under a specific load. Preferably, the tire cords may have an elongation of 4.0% to 5.0% or 4.0% to 4.5% under a specific load.

[0062] In one instance, tire cords can exhibit shrinkage rates of 3.0% to 6.0% when measured according to the ASTM D 885 standard test method (250 mm specimen length, 177°C, 2 minutes, 0.01 g / d load). Here, (+) shrinkage values ​​indicate shrinkage behavior, while (-) shrinkage values ​​indicate relaxation behavior.

[0063] Specifically, the tire cords may have a shrinkage rate of less than 6.0%, less than 5.9%, less than 5.8%, less than 5.7%, less than 5.6%, less than 5.5%, less than 5.4%, less than 5.3%, or less than 5.2%; and a shrinkage rate of more than 3.0%, more than 3.1%, or more than 3.2%.

[0064] Preferably, the tire cord may have a content of 3.0% to 5.9%, 3.0% to 5.8%, 3.0% to 5.7%, 3.0% to 5.6%, 3.0% to 5.5%, 3.0% to 5.4%, 3.0% to 5.3%, 3.0% to 5.2%, 3.1% to 5.9%, 3.1% to 5.8%, 3.1% to 5.7%, 3.1% to Shrinkage rates of 5.6%, 3.1% to 5.5%, 3.1% to 5.4%, 3.1% to 5.3%, 3.1% to 5.2%, 3.2% to 5.9%, 3.2% to 5.8%, 3.2% to 5.7%, 3.2% to 5.6%, 3.2% to 5.5%, 3.2% to 5.4%, 3.2% to 5.3%, or 3.2% to 5.2%.

[0065] In one example, tire cord can exhibit a strength ratio of over 88.5%. Here, the strength ratio is a value calculated using the equation {[(tensile strength of tire cord) / (tensile strength of polyester filament)]×100}.

[0066] Specifically, the tire cords may have a strength ratio of 88.5% or more, 88.6% or more, 88.7% or more, 88.8% or more, or 88.9% or more; and a strength ratio of 91.0% or less, 90.8% or less, 90.6% or less, or 90.4% or less.

[0067] Preferably, the tire cords may have a strength ratio of 88.5% to 91.0%, 88.5% to 90.8%, 88.6% to 90.8%, 88.6% to 90.6%, 88.7% to 90.6%, 88.7% to 90.4%, 88.8% to 90.4%, or 88.9% to 90.4%.

[0068] Meanwhile, the polyester filaments included in tire cords can be filaments made from PET materials obtained by using recycled PET and virgin PET.

[0069] In order to give the tire cord the above physical properties, the polyester filaments included in the tire cord may have a tensile strength of 8.0 g / d to 9.0 g / d and an elongation at break of 14.0% to 17.0%.

[0070] Specifically, the polyester drawing yarn can have a tensile strength of 8.0 g / d or more or 8.1 g / d or more; and a tensile strength of 9.0 g / d or less, 8.9 g / d or less or 8.8 g / d or less.

[0071] In addition, the polyester drawing yarn can have an elongation at break of more than 14.0%, more than 14.5%, or more than 15.0%; and less than 17.0%, less than 16.5%, less than 16.0%, or less than 15.6%.

[0072] Preferably, the polyester drawing filament may have a tensile strength of 8.1 g / d to 9.0 g / d, 8.1 g / d to 8.9 g / d, or 8.1 g / d to 8.8 g / d; and an elongation at break of 14.5% to 17.0%, 14.5% to 16.5%, 14.5% to 16.0%, 14.5% to 15.6%, or 15.0% to 15.6%.

[0073] Polyester drawn yarns can have a total draw ratio of 1.0 to 3.0, 1.5 to 3.0, or 1.5 to 2.5. To increase orientation through stretching and exhibit appropriate strength, the total draw ratio of the polyester drawn yarn is preferably 1.0 or higher. However, to prevent breakage due to overstretching, the total draw ratio of the polyester drawn yarn is preferably 3.0 or lower.

[0074] When measured according to the ASTM D 885 standard test method (sample length 250 mm, 177°C, 2 minutes, 0.01 g / d load), polyester drawn yarn may exhibit a shrinkage rate of 9.5% to 15.0%.

[0075] Specifically, polyester drawn yarns can exhibit shrinkage rates of less than 15.0%, less than 14.5%, less than 14.0%, or less than 13.7%; and more than 9.5%, more than 9.6%, more than 9.7%, or more than 9.8%.

[0076] Preferably, the polyester drawn yarn can exhibit a shrinkage rate of 9.6% to 15.0%, 9.6% to 14.5%, 9.7% to 14.5%, 9.7% to 14.0%, or 9.8% to 13.7%.

[0077] Meanwhile, polyester drawn yarns can be obtained by melt spinning and drawing recycled PET containing 25% to 95% by weight of intrinsic viscosity of 0.9 dl / g to 1.5 dl / g and isophthalic acid content based on a total carboxylic acid composition of less than 1.0 mol%.

[0078] To ensure the material is fully melted while preventing excessive thermal decomposition and guaranteeing excellent spinnability, the melting of the material can be carried out at temperatures of 250°C to 320°C, 260°C to 310°C, or 270°C to 300°C.

[0079] The spinning speed of melt spinning is preferably adjusted to be above 2000 m / min and less than 4000 m / min, 2000 m / min to 3500 m / min, or 2000 m / min to 3000 m / min. The spinning speed can be adjusted according to the physical properties of the material. However, when the spinning speed is too high, breakage may occur, making the yarn difficult to manufacture.

[0080] Undrawn yarns obtained by melt spinning can be cooled at temperatures ranging from 15°C to 60°C.

[0081] Alternatively, undrawn yarn can be drawn within the aforementioned range using a drawing machine with multiple rollers.

[0082] Following the stretching process, additional heat setting, relaxation, and winding processes can be performed. In one example, the relaxation process can be carried out at a relaxation rate of 1% to 3%. To prevent breakage due to excessive tension, the relaxation rate is preferably 1% or more. However, since airtightness or durability may deteriorate due to excessive relaxation, the relaxation rate is preferably below 3%.

[0083] Meanwhile, tire cords can be manufactured using conventional methods with drawn polyester yarns.

[0084] In one example, virgin cord can be manufactured by feeding polyester drawn yarn into a cable cord twisting machine and performing Z-twisting and S-twisting at a twist rate of 200 TPM to 500 TPM. Tire cord (rubber-impregnated cord) can be manufactured by immersing virgin cord in an adhesive coating liquid, followed by drying and heat treatment.

[0085] According to another embodiment of this disclosure, a tire including the aforementioned tire cords is provided.

[0086] Figure 1 This is a partial cross-sectional view of a tire 101 according to one embodiment of the present disclosure.

[0087] The tire cord can be used in at least one of the crown layer 90, the belt layer 50, and the carcass 70 of the tire 101.

[0088] Reference Figure 1 Tire 101 includes: tread 10, shoulder 20, sidewall 30, bead 40, belt layer 50, inner liner 60, carcass 70 and crown layer 90.

[0089] The tread 10 is the part that directly contacts the road surface. The tread 10 is a robust rubber layer attached to the outer side of the crown belt layer 90, made of rubber with excellent abrasion resistance. The tread 10 plays a direct role in transmitting the vehicle's driving and braking forces to the ground. Grooves 80 are formed in the area of ​​the tread 10.

[0090] The shoulder 20 is the corner section of the tread 10 and connects to the sidewall 30. Both the shoulder 20 and the sidewall 30 are among the weakest parts of the tire.

[0091] The sidewall 30 is a side portion of the tire 101 that connects the tread 10 and the bead 40, protects the tire carcass 70, and provides lateral stability to the tire.

[0092] The bead 40 is the area including the wire wrapped around the end of the tire carcass 70, and has a structure in which the wire is covered with a rubber membrane to wrap the cords. The bead 40 is used to mount and secure the tire 101 to the rim.

[0093] The belt layer 50 is a coating layer located between the tread 10 and the carcass 70. The belt layer 50 serves to prevent damage to internal components such as the carcass 70 due to external impacts or conditions, and allows the tread 10 to maintain a flat shape, thereby maintaining optimal contact between the tire 101 and the road surface. According to one embodiment of the invention, the belt layer 50 may include tire cords.

[0094] The inner liner 60 is used to replace the inner tube in a tubeless tire and is made of a special rubber with very low or no air permeability. The inner liner 60 prevents the air filling the tire 101 from leaking out.

[0095] The tire carcass 70 is made by overlapping multiple sheets of cord paper made of strong synthetic fibers and is an important component forming the skeleton of the tire 101. The tire carcass 70 is used to withstand the load or impact received by the tire 101 and to maintain air pressure. According to one embodiment of the invention, the belt layer 70 may include tire cords.

[0096] Groove 80 refers to the thicker gaps in the tread area. When driving on wet or slippery roads, groove 80 helps to increase tire drainage and grip.

[0097] The crown layer 90 is a protective layer beneath the tread 10 and protects other components therein. The crown layer 90 is primarily used in vehicles traveling at high speeds. In particular, as vehicle speeds increase, problems arise such as deterioration in ride comfort due to deformation of the tire's belt layer. Therefore, the importance of the crown layer 90 in preventing belt layer deformation is increasing. According to one embodiment of the invention, the crown layer 90 may include tire cords.

[0098] Beneficial effects

[0099] According to this disclosure, tire cords contain eco-friendly materials while exhibiting excellent physical properties required for industrial applications. Attached Figure Description

[0100] Figure 1 This is a partial cross-sectional view of a tire according to one embodiment of the present disclosure.

[0101] <Marker Description>

[0102] 10: Tread

[0103] 20: Fetal shoulder

[0104] 30: Sidewall

[0105] 40: Tire bead

[0106] 50: Belt layer

[0107] 60: Lining

[0108] 70: Fetus

[0109] 80: Groove

[0110] 90: Crown layer

[0111] 101: Tires Detailed Implementation

[0112] Preferred embodiments are presented below to aid in understanding the invention. However, the following embodiments are provided to illustrate implementations of the invention, and the invention is not limited to these embodiments.

[0113] Reference example

[0114] Raw PET chips with an intrinsic viscosity of 1.2 dl / g, made from terephthalic acid and ethylene glycol, were prepared. The raw PET chips were fed into a single-screw extruder and melted to prepare a melt for spinning.

[0115] The melt used for spinning is extruded through a spinneret to obtain polyester drawn yarn with a total fineness of 1000 denier (approximately 4 denier per yarn). The process for obtaining the polyester drawn yarn is carried out at a spinning temperature of 290°C, a spinning speed of 3000 m / min, a total draw ratio of 1.5, and a relaxation ratio of 1.5% (after heat treatment at 180°C).

[0116] Polyester drawn yarns were fed into a cable cord twisting machine and simultaneously subjected to 430 TPM Z-twisting and 430 TPM S-twisting to prepare two-ply yarns and raw cord. The raw cord was then impregnated in an adhesive coating solution containing resorcinol-formaldehyde-latex (RFL), dried at 150°C for 100 seconds, and then heat-treated at 240°C for 100 seconds to prepare tire cord (rubber-impregnated cord). The tension applied to the raw cord during the impregnation, drying, and heat treatment processes was 0.5 kg / cord.

[0117] Example 1

[0118] Based on the total dicarboxylic acid composition, chemically recycled PET chips (A) with an isophthalic acid content of 0.8 mol% (terephthalic acid content of 99.2 mol%) and an intrinsic viscosity of 1.2 dl / g were prepared.

[0119] Raw PET chips with an intrinsic viscosity of 1.2 dl / g were prepared from terephthalic acid and ethylene glycol.

[0120] A mixture containing 30% by weight of recycled PET chips (A) and 70% by weight of virgin PET chips is fed into a single-screw extruder and melted to prepare a melt for spinning.

[0121] The melt used for spinning is extruded through a spinneret to obtain polyester drawn yarn with a total fineness of 1000 denier (approximately 4 denier per yarn). The process for obtaining the polyester drawn yarn is carried out at a spinning temperature of 290°C, a spinning speed of 2000 m / min, a total draw ratio of 2.5, and a relaxation rate of 1.5% (after heat treatment at 180°C).

[0122] Except for using polyester drawn yarn, tire cords are manufactured in the same manner as in the reference example.

[0123] Example 2

[0124] Except for applying a spinning speed of 3000 m / min and a total stretch ratio of 1.5 times to the process of obtaining polyester drawn yarn, the tire cord was manufactured in the same manner as in Example 1.

[0125] Example 3

[0126] The tire cord was manufactured in the same manner as in Example 2, except that a chemically recycled PET chip (B) with an isophthalic acid content of 0.8 mol% based on the total dicarboxylic acid composition (99.2 mol% terephthalic acid content) and an intrinsic viscosity of 1.0 dl / g was used instead of a chemically recycled PET chip (A).

[0127] Comparative Example 1

[0128] The tire cord was manufactured in the same manner as in Example 1, except that the chemically recycled PET chips (C) with an isophthalic acid content of 0.8 mol% based on the total dicarboxylic acid composition (99.2 mol% terephthalic acid content) and an intrinsic viscosity of 0.8 dl / g were used instead of the chemically recycled PET chips (A).

[0129] Comparative Example 2

[0130] The tire cord was manufactured in the same manner as in Example 2, except that the chemically recycled PET chips (C) with an isophthalic acid content of 0.8 mol% based on the total dicarboxylic acid composition (99.2 mol% terephthalic acid content) and an intrinsic viscosity of 0.8 dl / g were used instead of the chemically recycled PET chips (A).

[0131] Comparative Example 3

[0132] The tire cord was manufactured in the same manner as in Example 2, except that the chemically recycled PET chips (D) with an isophthalic acid content of 1.0 mol% based on the total dicarboxylic acid composition (99.0 mol% terephthalic acid content) and an intrinsic viscosity of 1.2 dl / g were used instead of the chemically recycled PET chips (A).

[0133] Example 4

[0134] Except for the use of 50% by weight of recycled PET chips (A) and 50% by weight of virgin PET chips in the preparation of the melt for spinning, the tire cord was manufactured in the same manner as in Example 1.

[0135] Example 5

[0136] Except for the use of 70% by weight of recycled PET chips (A) and 30% by weight of virgin PET chips in the preparation of the melt for spinning, the tire cord was manufactured in the same manner as in Example 1.

[0137] Example 6

[0138] The tire cord was manufactured in the same manner as in Example 1, except that 100% by weight of recycled PET chips (A) were used instead of virgin PET chips in the preparation of the melt for spinning.

[0139] Example 7

[0140] The tire cord was manufactured in the same manner as in Example 1, except that the chemically recycled PET chips (A) were replaced with chemically recycled PET chips (E) having an isophthalic acid content of 0 mol% based on the total dicarboxylic acid composition (100 mol% terephthalic acid content) and an intrinsic viscosity of 1.2 dl / g.

[0141] Comparative Example 4

[0142] Except that chemically recycled PET chips (A) are used instead of chemically recycled PET chips (F) with an isophthalic acid content of 0.8 mol% based on the total dicarboxylic acid composition (99.2 mol% terephthalic acid content) and an intrinsic viscosity of 1.6 dl / g, the original cord and the sizing cord are manufactured in the same manner as in Example 1.

[0143] Test case

[0144] (1) Isophthalic acid content in PET chips

[0145] Samples were prepared by dissolving PET slices in trifluoroacetic acid D (system peak: 11.50) at a concentration of 2% to 3%. The isophthalic acid (IPA) content in the samples was measured by 64 MHz H-NMR analysis using an NMR apparatus (AS400; manufactured by Oxford Instruments).

[0146] *IPA peak value: (a)8.7-8.8ppm, (b)8.2-8.3ppm, (c)7.5-7.6ppm

[0147] *IPA content (mol%) = {[(a) area + (b) area + (c) area] × 100} / (total area)

[0148] (2) Intrinsic viscosity of resin

[0149] The emulsion was extracted from PET slices using carbon tetrachloride, and the PET slices were melted in o-chlorophenol (OCP) at 160±2 °C to prepare samples. The viscosity of the samples in the viscometer was measured at 25 °C using an automatic viscometer (Skyvis-4000; SKC Limited, Korea), and the intrinsic viscosity (IV) was then measured using the equation below.

[0150] *Intrinsic viscosity (IV) = {(0.0242 × Rel) + 0.2634} × F

[0151] *Rel=[(sample flow time)×(sample specific gravity)×(viscosity coefficient)] / (viscosity of OCP)

[0152] *F = (IV of standard slice) / (average of three IVs measured on the standard slice in standard operation)

[0153] (3) Tensile strength, elongation at break and elongation under specific load

[0154] The tensile strength (g / d) and elongation at break (%) of polyester filament and tire cord were measured using an Instron universal testing machine according to the standard test method of ASTM D 885. The specimen length was 250 mm, the elongation rate was 300 mm / min, and the initial load was set to 0.05 g / d.

[0155] The elongation at a load of 4.5 g / d in the stress-strain curve obtained from the above experiment is expressed as "elongation at a specific load".

[0156] (4) Shrinkage rate

[0157] According to the standard test method of ASTM D 885, a 250 mm long specimen was placed at 25°C and 65% RH for 24 hours, and then its length (L0) was measured under a load of 0.01 g / d. After applying a load of 0.05 g / d to the specimen and heating it at 177°C for 2 minutes, the length (L1) of the specimen was measured. Five measurements of L0 and L1 were performed, and the change in specimen length {=[(L0-L1) / L0]×100} is expressed as the shrinkage rate. Here, (+) shrinkage values ​​represent shrinkage behavior, while (-) shrinkage values ​​represent relaxation behavior.

[0158] [Table 1]

[0159] Reference example 8.6 16.1 +10.2 ◎ Example 1 8.6 15.4 +13.7 ◎ Example 2 8.4 15.6 +10.4 ○ Example 3 8.1 15.0 +9.8 ○ Example 4 8.5 15.3 +13.6 ○ Example 5 8.3 15.2 +13.4 ○ Example 6 8.1 15.0 +13.2 ○ Example 7 8.8 15.5 +13.6 ◎ Comparative Example 1 7.5 13.2 +12.5 ◎ Comparative Example 2 7.2 13.5 +9.5 ◎ Comparative Example 3 7.3 12.7 +10.4 △ Comparative Example 4 7.8 14.1 +13.9 △

[0160] [Table 2]

[0161]

[0162]

[0163] Referring to Tables 1 and 2, it was confirmed that the tire cord according to the embodiment is eco-friendly because it contains recycled PET and exhibits the same physical properties as the tire cord of the reference example.

[0164] In Comparative Examples 3 and 4, the polyester drawn yarn could be wound up, but a large amount of fuzz and frequent breakage occurred, resulting in yarn of relatively poor quality.

Claims

1. A tire cord comprising an adhesive and raw cord. in, The original cord yarn is a polyester ply yarn composed of polyester drawn filaments with a bus density of 1000 to 9000 denier. The polyester drawn yarn consists of a mixture of 30% to 100% by weight recycled polyethylene terephthalate and 0% to 70% by weight virgin polyethylene terephthalate, wherein the recycled polyethylene terephthalate has an intrinsic viscosity of 0.90 dl / g to 1.30 dl / g and an isophthalic acid content of 0 mol% to 0.95 mol% based on the total carboxylic acid composition. The polyester drawn yarn has a tensile strength of 8.1 g / d to 8.8 g / d and an elongation at break of 15.0% to 15.6%. Specifically, when measured according to the standard test method of ASTM D 885, the tire cord has a tensile strength of 7.2 g / d to 7.9 g / d and an elongation at break of 15.5% to 16.6%.

2. The tire cord according to claim 1, in, The tire cord has a strength ratio of over 88.5% {=[(tensile strength of tire cord) / (tensile strength of polyester drawn yarn)]×100}.

3. The tire cord according to claim 1, in, When measured under a load of 4.5 g / d according to the ASTM D 885 standard test method, the tire cord has an elongation of 3.5% to 5.0% under a specific load.

4. The tire cord according to claim 1, in, When measured according to the ASTM D 885 standard test method (sample length 250 mm, 177°C, 2 minutes, 0.01 g / d load), the tire cord has a shrinkage rate of 3.0% to 6.0%.

5. The tire cord according to claim 1, in, When measured according to the ASTM D 885 standard test method (sample length 250 mm, 177°C, 2 minutes, 0.01 g / d load), the polyester drawing filament has a shrinkage rate of 9.5% to 15.0%.

6. The tire cord according to claim 1, in, The polyester drawing yarn has a total draw ratio of 1.0 to 3.

0.

7. The tire cord according to claim 1, in, The tire cord is a two-strand yarn comprising the polyester drawn yarn.

8. A tire comprising the tire cords as described in claim 1.

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