tire cord

Abstract

The present invention relates to a tire cord. The tire cord includes a polyester drawn yarn containing recycled polyethylene terephthalate. The tire cord includes an environmentally friendly material and exhibits excellent physical properties that meet the industrially required standards.

Description

[Technical Field]

[0001] The present invention relates to a tire cord comprising a polyester drawn yarn containing recycled polyethylene terephthalate. [Background technology]

[0002] As automobile performance improves and road conditions improve, tires are required to maintain stability and durability when traveling at high speeds. Furthermore, considering environmental issues, energy issues, and fuel efficiency, lightweight yet durable tires are required. As one measure to meet these demands, active research is being conducted on tire cords, which are used as rubber reinforcements in tires.

[0003] Tire cords are classified according to the part and role they are used in. For example, tire cords are broadly classified into carcass cords that support the entire tire, belt cords that support the load caused by high-speed driving and prevent deformation, and cap ply cords that prevent belt deformation (see Figure 1).

[0004] Meanwhile, many countries, including the European Union, are mandating the use of recycled materials in vehicle accessories as they tighten environmental regulations, and as a result, attempts are being made to use recyclable plastics (e.g., polyethylene terephthalate) that were previously discarded after being used as plastic containers or fibers in the manufacture of vehicle accessories.

[0005] However, recycled plastics have poorer physical properties than the original plastic materials, and deterioration of their physical properties due to thermal decomposition during the processing process is inevitable.

[0006] Therefore, there is a need for a method that overcomes the physical limitations of recycled plastics while still being environmentally friendly by using recycled plastics. Summary of the Invention [Problem to be solved by the invention]

[0007] The present invention provides a tire cord comprising a polyester drawn yarn containing recycled polyethylene terephthalate.

[0008] The present invention also provides a tire including the tire cord. [Means for solving the problem]

[0009] According to one embodiment of the present invention, The polyester drawn yarn contains 25% by weight or more of recycled polyethylene terephthalate having an intrinsic viscosity of 1.5 dl / g or less and an isophthalic acid content of less than 1.0 mol% relative to the total carboxylic acid components, It has a tensile strength of 7.0 g / d to 8.0 g / d and an elongation at break of 15.0% to 17.5% according to the standard test method of ASTM D 885. A tire cord is provided.

[0010] According to another embodiment of the present invention, there is provided a tire including the tire cord.

[0011] Hereinafter, tire cords according to embodiments of the present invention and tires including the same will be described in more detail.

[0012] Unless otherwise defined herein, all technical and scientific terms have the same meaning as commonly understood by a person of ordinary skill in the art to which this invention belongs. The terms used in describing the present invention are merely for the purpose of effectively describing specific embodiments and are not intended to limit the present invention.

[0013] As used herein, the singular forms include the plural forms unless the context clearly dictates otherwise.

[0014] As used herein, the meaning of "comprising" embodies certain properties, regions, integers, steps, operations, elements, and / or components, and does not exclude the presence or addition of other certain properties, regions, integers, steps, operations, elements, components, and / or groups.

[0015] The present invention can be modified in various ways and can have various forms, and therefore, specific embodiments will be illustrated and described in detail below. However, it should be understood that the present invention is not intended to be limited to the specific disclosed forms, but rather to include all modifications, equivalents, and alternatives within the spirit and technical scope of the invention.

[0016] In this specification, when the positional relationship of two parts is described using terms such as 'above', 'on top of', 'below', 'beside', etc., one or more other parts may be located between the two parts, unless the terms 'immediately' or 'directly' are used.

[0017] In this specification, when a temporal relationship is described using terms such as 'after', 'following', 'next', 'before', etc., it may also include cases where the relationship is not consecutive, unless the terms 'immediately' or 'directly' are used.

[0018] As used herein, the term 'at least one' should be understood to include all possible combinations of one or more of the associated items.

[0019] As used herein, the terms 'recycled polyethylene terephthalate', 'recycled PET' or 'r-PET' refer to polyethylene terephthalate (PET) resin that has been recycled for reuse after being discarded after its original use, such as various containers, films, sheets, fibers, etc.

[0020] As used herein, the terms 'virgin polyethylene terephthalate', 'virgin PET', or 'v-PET' are used to distinguish them from recycled polyethylene terephthalate, recycled PET, or r-PET, and refer to the original, unrecycled PET resin used to manufacture various containers, films, sheets, fibers, etc.

[0021] As used herein, the term 'primarily twisted yarn' refers to a single yarn made by twisting one filament in any one direction.

[0022] As used herein, the term 'plied yarn' means a yarn made by twisting two or more plied yarns together in one direction, and may also be referred to as a 'raw-cord'.

[0023] In this specification, the term 'tire cord' means a ply-twisted yarn containing an adhesive so that it can be immediately applied to rubber products for tires, and may also be called a 'dip-cord'.

[0024] Tire cord yarns made from recycled PET generally do not have high strength. One reason for this is the low intrinsic viscosity of recycled PET. If the material has a low intrinsic viscosity, it is difficult to orient the polymer during yarn production. This makes it difficult to impart the required spinning tension to the yarn, limiting the strength that can be achieved.

[0025] Due to supply and cost reasons, recycled PET is mostly obtained from discarded PET bottles. However, PET bottles contain isophthalic acid, which gives them high flexibility, and a large amount of catalysts to improve reactivity. The additives, such as isophthalic acid and catalysts, contained in recycled PET can act as defects in the production of tire cord yarn.

[0026] This is because, in order to produce tire cord yarn, a high-speed spinning method is required to impart high tension, and the additives may act as an obstruction to the axial orientation of the yarn.

[0027] However, as a result of the inventors' continued research, it was found that tire cords that are environmentally friendly and have excellent physical properties can be provided by using polyester drawn yarn obtained by controlling the range of intrinsic viscosity of recycled PET and the range of isophthalic acid content.

[0028] According to one embodiment of the invention, The polyester yarn contains 25% by weight or more of recycled PET 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 the total carboxylic acid component, It has a tensile strength of 7.0 g / d to 8.0 g / d and an elongation at break of 15.0% to 17.5% according to the standard test method of ASTM D 885. A tire cord is provided.

[0029] In melt spinning to produce yarn, the raw material must be melted at a temperature above its melting point. However, raw materials with high crystallinity have a high melting point, necessitating a higher melting temperature for the melt spinning process. This increase in process temperature not only increases energy consumption and costs, such as the need for equipment modifications, but also leads to thermal decomposition of the raw material and the resulting deterioration of the properties of the yarn. In particular, recycled PET typically undergoes a process of melting waste PET during its recovery, which can exacerbate the aforementioned problems when using recycled PET for melt spinning.

[0030] However, by using recycled PET 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% relative to the total carboxylic acid component, the crystallinity of the recycled PET can be controlled to an appropriate level, thereby preventing the above-mentioned problems. In other words, by using recycled PET whose intrinsic viscosity and isophthalic acid content are controlled within the above ranges, it is possible to provide tire cords that are environmentally friendly and have excellent physical properties.

[0031] In one example, the recycled PET may have an isophthalic acid content of less than 1.0 mol%, alternatively 0.95 mol% or less, alternatively 0.9 mol% or less, alternatively 0.85 mol% or less, or alternatively 0.8 mol% or less, based on the total dicarboxylic acid components contained in the recycled PET.

[0032] Preferably, the recycled PET has a dicarboxylic acid content of 0 mol% or more and less than 1.0 mol%, alternatively 0 mol% to 0.95 mol%, alternatively 0 mol% to 0.9 mol%, alternatively 0 mol% to 0.85 mol%, alternatively 0 mol% to 0.8 mol%, alternatively 0.1 mol% or more and less than 1.0 mol%, alternatively 0.1 mol% to 0.95 mol%, alternatively 0.1 mol% to 0.9 mol%, alternatively 0.1 mol% to 0.85 mol%, alternatively 0.1 mol% to 0.8 mol%, alternatively from 0.25 mol% to less than 1.0 mol%, alternatively from 0.25 mol% to 0.95 mol%, alternatively from 0.25 mol% to 0.9 mol%, alternatively from 0.25 mol% to 0.85 mol%, alternatively from 0.25 mol% to 0.8 mol%, alternatively from 0.5 mol% to less than 1.0 mol%, alternatively from 0.5 mol% to 0.95 mol%, alternatively from 0.5 mol% to 0.9 mol%, alternatively from 0.5 mol% to 0.85 mol%, alternatively from 0.5 mol% to 0.8 mol%.

[0033] The recycled PET has a dicarboxylic acid content of more than 99.0 mol% to 100.0 mol%, or 99.05 mol% to 100.0 mol%, or 99.10 mol% to 100.0 mol%, or 99.15 mol% to 100.0 mol%, or 99.20 mol% to 100.0 mol%, or more than 99.0 mol% to 99.9 mol%, or 99.05 mol% to 99.9 mol%, or 99.10 mol% to 99.9 mol%, or 99.15 mol% to 99.9 mol%, or 99.20 mol% to It may have a terephthalic acid content of 99.9 mol%, alternatively from greater than 99.0 mol% to 99.75 mol%, alternatively from 99.05 mol% to 99.75 mol%, alternatively from 99.10 mol% to 99.75 mol%, alternatively from 99.15 mol% to 99.75 mol%, alternatively from 99.20 mol% to 99.75 mol%, alternatively from greater than 99.0 mol% to 99.50 mol%, alternatively from 99.05 mol% to 99.50 mol%, alternatively from 99.10 mol% to 99.50 mol%, alternatively from 99.15 mol% to 99.50 mol%, alternatively from 99.20 mol% to 99.50 mol%.

[0034] Here, the content of isophthalic acid and terephthalic acid refers to the content of isophthalic acid, terephthalic acid, or units derived therefrom based on the total dicarboxylic acids or units derived therefrom contained in the recycled PET. The content of isophthalic acid and terephthalic acid can be obtained by calculating the peak intensity of a predetermined proton through NMR measurement of the recycled PET and then calculating the content (mol %) of isophthalic acid and terephthalic acid components in 100 mol % of dicarboxylic acid components.

[0035] In another example, the recycled PET may have an intrinsic viscosity of 0.9 dL / g to 1.5 dL / g. As will be seen in the following examples, if the recycled PET has an intrinsic viscosity of less than 0.9 dL / g, the tensile strength and elongation at break of the polyester oriented yarn and tire cord containing the recycled PET may be insufficient. However, if the recycled PET has an intrinsic viscosity of more than 1.5 dL / g, the high viscosity can cause poor polymer flow during the production of polyester oriented yarn and tire cord, increasing nozzle pressure (pack pressure). This can lead to pack leaks, resulting in excessive fuzz and frequent yarn breakage.

[0036] Specifically, the recycled PET may have an intrinsic viscosity of 0.9 dl / g or more, alternatively 0.95 dl / g or more, or alternatively 1.0 dl / g or more, and may have an intrinsic viscosity of 1.5 dl / g or less, alternatively 1.45 dl / g or less, alternatively 1.4 dl / g or less, alternatively 1.35 dl / g or less, alternatively 1.3 dl / g or less, alternatively 1.25 dl / g or less, or alternatively 1.2 dl / g or less.

[0037] Preferably, the recycled PET has a viscosity of 0.90 dl / g to 1.45 dl / g, alternatively 0.90 dl / g to 1.40 dl / g, alternatively 0.90 dl / g to 1.35 dl / g, alternatively 0.90 dl / g to 1.30 dl / g, alternatively 0.90 dl / g to 1.25 dl / g, alternatively 0.90 dl / g to 1.20 dl / g, alternatively 0.95 dl / g to 1.50 dl / g, alternatively 0.95 dl / g to 1.45 dl / g, alternatively 0.95 dl / g to 1.40 dl / g, alternatively 0.95 dl / g to 1.35 dl / g , or from 0.95 dl / g to 1.30 dl / g, or from 0.95 dl / g to 1.25 dl / g, or from 0.95 dl / g to 1.20 dl / g, 1.00 dl / g to 1.50 dl / g, or from 1.00 dl / g to 1.45 dl / g, or from 1.00 dl / g to 1.40 dl / g, or from 1.00 dl / g to 1.35 dl / g, or from 1.00 dl / g to 1.30 dl / g, or from 1.00 dl / g to 1.25 dl / g, or from 1.00 dl / g to 1.20 dl / g.

[0038] The intrinsic viscosity can be measured by dissolving a resin to be measured in an organic solvent to prepare a sample solution, and then using an Ubbelohde viscometer and an aspirator, or an automatic viscometer.

[0039] The content of the recycled PET in the oriented polyester yarn is preferably 25% by weight or more, or 25% to 100% by weight, or 30% to 100% by weight. That is, from the viewpoint of environmental protection and resource recycling, the recycled PET is preferably contained in the oriented polyester yarn at 25% by weight or more, or 30% by weight or more.

[0040] Alternatively, the content of recycled PET can be adjusted by the recycling method from which the recycled PET is derived.

[0041] For example, if the recycled PET is derived from a chemical recycling method, the recycled PET content in the polyester oriented yarn may be 25% to 100% by weight, or 30% to 100% by weight. Chemically recycled PET, which is obtained by changing the chemical structure of waste PET through depolymerization, hydrolysis, and repolymerization, can exhibit relatively excellent and stable physical properties. Accordingly, the chemically recycled PET may be contained in the polyester oriented yarn in a content of up to 100% by weight.

[0042] As another example, if the recycled PET is derived from a physical recycling method, the recycled PET content in the polyester oriented yarn may be 25% to 95% by weight, or 30% to 90% by weight. Physically recycled PET, which is obtained as flakes through the collection, color sorting, crushing, washing, and drying of waste PET, has relatively large variations in physical properties. Therefore, it is necessary to consider the deterioration of physical properties due to thermal decomposition during processing using this as a raw material. Accordingly, it is preferable that the physically recycled PET be contained in the polyester oriented yarn at 95% by weight or less, or 90% by weight or less.

[0043] In one example, the polyester oriented yarn may contain virgin PET together with the recycled PET. Preferably, the polyester oriented yarn contains the recycled PET in the above content range, with the remainder being virgin PET. The virgin PET may be free of isophthalic acid or units derived therefrom.

[0044] Preferably, the virgin PET may have an intrinsic viscosity of 0.8 dL / g to 1.4 dL / g in order to prevent the occurrence of a large amount of fluff and yarn breakage while ensuring sufficient tensile strength and elongation at break in polyester drawn yarn and tire cord.

[0045] Specifically, the virgin PET may have an intrinsic viscosity of 0.8 dl / g or more, alternatively 0.85 dl / g or more, alternatively 0.9 dl / g or more, alternatively 0.95 dl / g or more, or alternatively 1.0 dl / g or more, and may have an intrinsic viscosity of 1.4 dl / g or less, alternatively 1.35 dl / g or less, alternatively 1.3 dl / g or less, or alternatively 1.25 dl / g or less.

[0046] More preferably, the virgin PET may have an intrinsic viscosity of 0.8 dl / g to 1.4 dl / g, alternatively 0.85 dl / g to 1.4 dl / g, alternatively 0.85 dl / g to 1.35 dl / g, alternatively 0.9 dl / g to 1.35 dl / g, alternatively 0.9 dl / g to 1.3 dl / g, alternatively 0.95 dl / g to 1.3 dl / g, alternatively 0.95 dl / g to 1.25 dl / g, alternatively 1.0 dl / g to 1.25 dl / g.

[0047] Meanwhile, the polyester oriented yarn contained in the tire cord may have an appropriate fineness to a level that satisfies the physical properties according to the present invention. For example, the polyester oriented yarn may have a single yarn fineness of 2 denier to 15 denier and a total fineness of 500 denier to 3000 denier.

[0048] The tire cord includes a raw-cord made by twisting two or more of the polyester oriented yarns together in one direction, and an adhesive attached to the raw-cord.

[0049] Preferably, the tire cord may include the raw cord having a total fineness of 1000 denier to 9000 denier, alternatively 1000 denier to 8000 denier, alternatively 1000 denier to 7000 denier, or alternatively 1000 denier to 6000 denier.

[0050] Preferably, the tire cord may be a two-ply yarn including the polyester drawn yarn. As a non-limiting example, the raw cord may be a two-ply yarn including the polyester drawn yarn having a fineness of 500 denier to 3000 denier, and have a total fineness of 1000 denier to 6000 denier.

[0051] The tire cord contains the recycled PET, which allows it to exhibit excellent properties in terms of contributing to environmental protection. Furthermore, the tire cord contains a polyester drawn yarn containing recycled PET that satisfies the aforementioned ranges of intrinsic viscosity and isophthalic acid content, allowing it to exhibit mechanical properties and dimensional stability at the same level as tire cords made using only virgin PET.

[0052] In one example, the tire cord can exhibit a tensile strength of 7.0 g / d to 8.0 g / d and an elongation at break of 15.0% to 17.5% according to the standard test method of ASTM D 885.

[0053] Specifically, the tire cord can exhibit a tensile strength of 7.0 g / d or greater, alternatively 7.1 g / d or greater, alternatively 7.2 g / d or greater; and 8.0 g / d or less, alternatively 7.95 g / d or less, alternatively 7.9 g / d or less.

[0054] The tire cord may exhibit an elongation at break of 15.0% or more, alternatively 15.1% or more, alternatively 15.2% or more, alternatively 15.3% or more, alternatively 15.4% or more, alternatively 15.5% or more; and 17.5% or less, alternatively 17.2% or less, alternatively 17.0% or less, alternatively 16.9% or less, alternatively 16.8% or less, 16.7% or less, or 16.6% or less.

[0055] Preferably, the tire cord can exhibit a tensile strength of 7.1 g / d to 8.0 g / d, alternatively 7.1 g / d to 7.95 g / d, alternatively 7.2 g / d to 7.95 g / d, alternatively 7.2 g / d to 7.9 g / d, alternatively 7.2 g / d to 7.9 g / d; and an elongation at break of 15.1% to 17.5%, alternatively 15.1% to 17.2%, alternatively 15.2% to 17.2%, alternatively 15.2% to 17.0%, alternatively 15.3% to 17.0%, alternatively 15.3% to 16.9%, alternatively 15.4% to 16.9%, alternatively 15.4% to 16.8%, alternatively 15.5% to 16.8%, alternatively 15.5% to 16.7%, alternatively 15.5% to 16.6%.

[0056] The tensile strength and elongation at break can be measured according to the standard test method of ASTM D 885 using a general-purpose testing machine.

[0057] In one example, the tire cord may have an intermediate elongation of 3.5% to 5.0% measured under a load of 4.5 g / d in accordance with the standard test method of ASTM D 885. The intermediate elongation refers to the elongation at a load of 4.5 g / d in the stress-strain curve obtained when measuring the tensile strength and elongation at break.

[0058] Specifically, the tire cord may have an intermediate elongation of 3.5% or more, or 4.0% or more, and 5.0% or less, or 4.5% or less. Preferably, the tire cord may have an intermediate elongation of 4.0% to 5.0%, or 4.0% to 4.5%.

[0059] In one example, the tire cord may exhibit a dry heat shrinkage of 3.0% to 6.0% according to the standard test method of ASTM D 885 (specimen length 250 mm, 177°C, 2 minutes, load 0.01 g / d), where (+) indicates shrinkage behavior, and (-) indicates relaxation behavior.

[0060] Specifically, the tire cord may exhibit a dry heat shrinkage of 6.0% or less, alternatively 5.9% or less, alternatively 5.8% or less, alternatively 5.7% or less, alternatively 5.6% or less, alternatively 5.5% or less, alternatively 5.4% or less, alternatively 5.3% or less, alternatively 5.2% or less; and 3.0% or more, alternatively 3.1% or more, alternatively 3.2% or more.

[0061] Preferably, the tire cord has a tensile strength of 3.0% to 5.9%, alternatively 3.0% to 5.8%, alternatively 3.0% to 5.7%, alternatively 3.0% to 5.6%, alternatively 3.0% to 5.5%, alternatively 3.0% to 5.4%, alternatively 3.0% to 5.3%, alternatively 3.0% to 5.2%, alternatively 3.1% to 5.9%, alternatively 3.1% to 5.8%, alternatively 3.1% to 5.7%, alternatively 3.1% to 5.6%, or Alternatively, the dry heat shrinkage may be 3.1% to 5.5%, alternatively 3.1% to 5.4%, alternatively 3.1% to 5.3%, alternatively 3.1% to 5.2%, alternatively 3.2% to 5.9%, alternatively 3.2% to 5.8%, alternatively 3.2% to 5.7%, alternatively 3.2% to 5.6%, alternatively 3.2% to 5.5%, alternatively 3.2% to 5.4%, alternatively 3.2% to 5.3%, or alternatively 3.2% to 5.2%.

[0062] In one example, the tire cord may exhibit a tenacity utilization rate of 88.5% or more, where the tenacity utilization rate is a value calculated by the formula {[(tensile strength of the tire cord) / (tensile strength of the polyester oriented yarn)]×100}.

[0063] Specifically, the tire cord may exhibit a strength utilization rate of 88.5% or more, alternatively 88.6% or more, alternatively 88.7% or more, alternatively 88.8% or more, alternatively 88.9% or more; and 91.0% or less, alternatively 90.8% or less, alternatively 90.6% or less, or alternatively 90.4% or less.

[0064] Preferably, the tire cord can exhibit a strength utilization rate of 88.5% to 91.0%, alternatively 88.5% to 90.8%, alternatively 88.6% to 90.8%, alternatively 88.6% to 90.6%, alternatively 88.7% to 90.6%, alternatively 88.7% to 90.4%, alternatively 88.8% to 90.4%, alternatively 88.9% to 90.4%.

[0065] On the other hand, the polyester drawn yarn contained in the tire cord may be a drawn yarn made of a PET material obtained by using the recycled PET and the virgin PET.

[0066] In order to enable the tire cord to exhibit the above-mentioned physical properties, the polyester drawn yarn contained 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%.

[0067] Specifically, the polyester drawn yarn may have a tensile strength of 8.0 g / d or more, alternatively 8.1 g / d or more; and 9.0 g / d or less, alternatively 8.9 g / d or less, alternatively 8.8 g / d or less.

[0068] The polyester drawn yarn may have an elongation at break of 14.0% or more, alternatively 14.5% or more, alternatively 15.0% or more; and 17.0% or less, alternatively 16.5% or less, alternatively 16.0% or less, alternatively 15.6% or less.

[0069] Preferably, the polyester drawn yarn has a tensile strength of 8.1 g / d to 9.0 g / d, alternatively 8.1 g / d to 8.9 g / d, alternatively 8.1 g / d to 8.8 g / d; and an elongation at break of 14.5% to 17.0%, alternatively 14.5% to 16.5%, alternatively 14.5% to 16.0%, alternatively 14.5% to 15.6%, alternatively 15.0% to 15.6%.

[0070] The polyester oriented yarn may have a total draw ratio of 1.0 to 3.0, or 1.5 to 3.0, or 1.5 to 2.5. To increase the degree of orientation through drawing and thereby achieve an appropriate level of strength, the total draw ratio of the polyester oriented yarn is preferably 1.0 or more. However, to prevent yarn breakage due to excessive drawing, the total draw ratio of the polyester oriented yarn is preferably 3.0 or less.

[0071] The polyester drawn yarn may exhibit a dry heat shrinkage of 9.5% to 15.0% according to the standard test method of ASTM D 885 (specimen length 250 mm, 177°C, 2 minutes, load 0.01 g / d).

[0072] Specifically, the polyester oriented yarn may exhibit a dry heat shrinkage of 15.0% or less, alternatively 14.5% or less, alternatively 14.0% or less, alternatively 13.7% or less; and 9.5% or more, alternatively 9.6% or more, alternatively 9.7% or more, alternatively 9.8% or more.

[0073] Preferably, the polyester drawn yarn may exhibit a dry heat shrinkage of 9.6% to 15.0%, alternatively 9.6% to 14.5%, alternatively 9.7% to 14.5%, alternatively 9.7% to 14.0%, or alternatively 9.8% to 13.7%.

[0074] On the other hand, the polyester drawn yarn can be obtained by melt-spinning and drawing a material containing 25% to 95% by weight of recycled PET 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% relative to the total carboxylic acid component.

[0075] In order to sufficiently melt the material while preventing excessive thermal decomposition of the material and ensuring excellent spinnability, the material can be melted at a temperature of 250°C to 320°C, or 260°C to 310°C, or 270°C to 300°C.

[0076] The melt spinning speed is preferably adjusted to 2000 m / min or more but less than 4000 m / min, or 2000 m / min to 3500 m / min, or 2000 m / min to 3000 m / min. The spinning speed can be adjusted taking into consideration the physical properties of the material. However, if the spinning speed is too fast, yarn breakage may occur, making it difficult to produce the yarn.

[0077] The undrawn yarn obtained through the melt spinning can be cooled at a temperature of 15°C to 60°C.

[0078] The undrawn yarn can be drawn within the above range using a drawing device equipped with a plurality of rollers.

[0079] After the drawing process, additional processes of heat setting, relaxation, and winding can be performed. In one example, the relaxation process can be performed at a relaxation rate of 1% to 3%. To prevent yarn breakage due to excessively high tension, the relaxation rate is preferably 1% or more. However, since excessive relaxation can reduce airtightness or durability, the relaxation rate is preferably 3% or less.

[0080] On the other hand, the tire cord can be produced by a conventional method using the polyester drawn yarn.

[0081] In one example, raw cord can be produced by feeding the polyester drawn yarn into a cable cord twisting machine and performing first twisting and second twisting at a twist rate of 200 TPM to 500 TPM. Tire cord (dipped cord) can be produced by immersing the raw cord in an adhesive coating solution, followed by drying and heat treatment.

[0082] According to yet another embodiment of the invention, there is provided a tire including the tire cord described above.

[0083] FIG. 1 is a partial cutaway view of a tire 101 according to one embodiment of the present invention.

[0084] The tire cord may be applied to at least one of the cap ply 90 , the belt 50 , and the carcass 70 of the tire 101 .

[0085] Referring to FIG. 1, a tire 101 includes a tread 10, a shoulder 20, a sidewall 30, a bead 40, a belt 50, an inner liner 60, a carcass 70, and a cap ply 90.

[0086] The tread 10 is the part that comes into direct contact with the road surface. The tread 10 is a strong rubber layer attached to the outside of the cap ply 90 and is made of rubber with excellent abrasion resistance. The tread 10 plays a direct role in transmitting the driving force and braking force of the vehicle to the ground. Grooves 80 are formed in the tread 10 area.

[0087] The shoulder 20 is a corner portion of the tread 10, and is a portion connected to the sidewall 30. The shoulder 20, together with the sidewall 30, is one of the weakest portions of the tire.

[0088] The sidewall 30 is the lateral (side) portion of the tire 101 that connects the tread 10 and the bead 40, protects the carcass 70, and provides lateral stability to the tire.

[0089] The bead 40 is an area containing iron wire wrapped around the end of the carcass 70, and is constructed by covering the iron wire with a rubber membrane and then wrapping the cord. The bead 40 serves to mount and secure the tire 101 to the wheel rim.

[0090] The belt 50 is a coating layer located between the tread 10 and the carcass 70. The belt 50 serves to prevent damage to internal components such as the carcass 70 due to external impacts or external conditions, and maintains the shape of the tread 10 flat, thereby maintaining optimal contact between the tire 101 and the road surface. The belt 50 may include a tire cord according to one embodiment of the present invention.

[0091] The inner liner 60 is used in place of a tube in a tubeless tire and is made of a special rubber that has no or very little air permeability. The inner liner 60 prevents the air filled in the tire 101 from leaking out.

[0092] The carcass 70 is made of a plurality of layers of cords made of strong synthetic fibers and is an important part that forms the framework of the tire 101. The carcass 70 serves to withstand the load and impact that the tire 101 receives and to maintain the air pressure. The carcass 70 may include a tire cord according to one embodiment of the present invention.

[0093] The grooves 80 refer to the wide grooves or voids in the tread area. The grooves 80 improve the tire's drainage and improve the tire's grip when driving on a loose road surface.

[0094] The cap ply 90 is a protective layer under the tread 10 to protect other components therein. The cap ply 90 is essential for high-speed vehicles. In particular, as vehicle speeds increase, problems such as deformation of the belt portion of the tire and a deterioration in ride comfort have arisen, and the importance of the cap ply 90, which prevents deformation of the belt portion, has increased. The cap ply 90 may include a tire cord according to one embodiment of the present invention. [Effects of the Invention]

[0095] The tire cord according to the present invention can exhibit excellent physical properties that meet the industrially required standards while containing environmentally friendly materials. [Brief explanation of the drawings]

[0096] [Figure 1] 1 is a partial cutaway view of a tire according to one embodiment of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0097] Preferred examples are presented below to aid in understanding the invention, but the following examples are merely for the purpose of illustrating the invention and are not intended to limit the invention thereto. [Example]

[0098] Reference example Virgin PET chips made from terephthalic acid and ethylene glycol and having an intrinsic viscosity of 1.2 dL / g were prepared and fed into a single-screw extruder to melt the chips to prepare a melt for spinning.

[0099] The melt was extruded through a spinneret to obtain a polyester yarn having a total fineness of 1000 denier (single yarn fineness of about 4 denier). The process for obtaining the polyester yarn was carried out under the conditions of a spinning temperature of 290°C, a spinning speed of 3000 m / min, a total draw ratio of 1.5 times, and a relaxation rate of 1.5% (heat treatment at 180°C after drawing).

[0100] The polyester drawn yarn was fed into a cable cord twisting machine and subjected to a first twist at 430 TPM and a second twist at 430 TPM simultaneously to produce a two-plied yarn raw cord. The raw cord was immersed in an adhesive coating solution containing resorcinol-formaldehyde-latex (RFL), dried at 150°C for 100 seconds, and heat-treated at 240°C for 100 seconds to produce a tire cord (dipped cord). The tension applied to the raw cord during the immersion, drying, and heat-treatment processes was 0.5 kg / cord.

[0101] Example 1 Chemically recycled PET chips (A) were prepared, which had an isophthalic acid content of 0.8 mol % (terephthalic acid content of 99.2 mol %) relative to the total dicarboxylic acid components and an intrinsic viscosity of 1.2 dl / g.

[0102] Virgin PET chips formed from terephthalic acid and ethylene glycol and having an intrinsic viscosity of 1.2 dl / g were prepared.

[0103] A mixture containing 30% by weight of the recycled PET chips (A) and 70% by weight of the virgin PET chips was charged into a single-screw extruder and melted to prepare a melt for spinning.

[0104] The melt was extruded through a spinneret to obtain a polyester yarn having a total fineness of 1000 denier (single yarn fineness of about 4 denier). The process for obtaining the polyester yarn was carried out under the conditions of a spinning temperature of 290°C, a spinning speed of 2000 m / min, a total draw ratio of 2.5 times, and a relaxation rate of 1.5% (heat treatment at 180°C after drawing).

[0105] A tire cord was produced in the same manner as in the Reference Example, except that the polyester drawn yarn was used.

[0106] Example 2 A tire cord was produced in the same manner as in Example 1, except that a spinning speed of 3000 m / min and a total draw ratio of 1.5 times were applied in the step of obtaining the polyester drawn yarn.

[0107] Example 3 A tire cord was produced in the same manner as in Example 2, except that chemically recycled PET chips (B) having an isophthalic acid content of 0.8 mol % (terephthalic acid content of 99.2 mol %) relative to the total dicarboxylic acid components and an intrinsic viscosity of 1.0 dL / g were used instead of the chemically recycled PET chips (A).

[0108] Comparative Example 1 A tire cord was produced in the same manner as in Example 1, except that chemically recycled PET chips (C) having an isophthalic acid content of 0.8 mol % (terephthalic acid content of 99.2 mol %) relative to the total dicarboxylic acid components and an intrinsic viscosity of 0.8 dL / g were used instead of the chemically recycled PET chips (A).

[0109] Comparative Example 2 A tire cord was produced in the same manner as in Example 2, except that chemically recycled PET chips (C) having an isophthalic acid content of 0.8 mol % (terephthalic acid content of 99.2 mol %) relative to the total dicarboxylic acid components and an intrinsic viscosity of 0.8 dL / g were used instead of the chemically recycled PET chips (A).

[0110] Comparative Example 3 A tire cord was produced in the same manner as in Example 2, except that chemically recycled PET chips (D) having an isophthalic acid content of 1.0 mol% (terephthalic acid content of 99.0 mol%) relative to the total dicarboxylic acid components and an intrinsic viscosity of 1.2 dL / g were used instead of the chemically recycled PET chips (A).

[0111] Example 4 A tire cord was produced in the same manner as in Example 1, except that 50 wt % of the recycled PET chips (A) and 50 wt % of the virgin PET chips were used in the spinning melt preparation step.

[0112] Example 5 A tire cord was produced in the same manner as in Example 1, except that 70 wt % of the recycled PET chips (A) and 30 wt % of the virgin PET chips were used in the spinning melt preparation step.

[0113] Example 6 A tire cord was produced in the same manner as in Example 1, except that the virgin PET chips were not used in the step of preparing the melt for spinning, and 100 wt % of the recycled PET chips (A) were used.

[0114] Example 7 A tire cord was produced in the same manner as in Example 1, except that chemically recycled PET chips (E) having an intrinsic viscosity of 1.2 dL / g and an isophthalic acid content of 0 mol% (a terephthalic acid content of 100 mol%) relative to the total dicarboxylic acid components were used instead of the chemically recycled PET chips (A).

[0115] Comparative Example 4 Raw cords and dipped cords were produced in the same manner as in Example 1, except that chemically recycled PET chips (F) having an isophthalic acid content of 0.8 mol% (terephthalic acid content of 99.2 mol%) relative to the total dicarboxylic acid components and an intrinsic viscosity of 1.6 dL / g were used instead of the chemically recycled PET chips (A).

[0116] Test Example (1) Content of isophthalic acid in PET chips PET chips were dissolved in trifluoroacetic acid D (system peak: 11.50) at a concentration of 2% to 3% to prepare specimens. The isophthalic acid (IPA) content in the specimens was measured by 64 MHz H-NMR using an NMR device (AS400; manufactured by Oxford Instruments).

[0117] *IPA Peak: (a) 8.7~8.8ppm, (b) 8.2~8.3ppm, (c) 7.5~7.6ppm *IPA content (mol%) = {[(a) area + (b) area + (c) area] × 100} / (total area)

[0118] (2) Intrinsic viscosity of resin The oil was extracted from PET chips using carbon tetrachloride, and the PET chips were dissolved in o-chlorophenol (OCP) at 160±2°C to prepare a sample. The viscosity of the sample was measured in a viscosity tube using an automatic viscometer (Skyvis-4000; SKC Limited, Korea) at 25°C, and the intrinsic viscosity (IV) was calculated using the following formula:

[0119] *Intrinsic viscosity (IV)={(0.0242×Rel)+0.2634}×F *Rel = [(number of seconds of sample) x (specific gravity of sample) x (viscosity coefficient)] / (viscosity of OCP) *F = (IV of standard chip) / (average IV of three standard chips measured under standard operation)

[0120] (3) Tensile strength, elongation at break and elongation at intermediate temperature The tensile strength (g / d) and elongation at break (%) of the polyester oriented yarn 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 pulling speed was 300 mm / min, and the initial load was 0.05 g / d.

[0121] The elongation at a load of 4.5 g / d in the stress-strain curve obtained in the above test was designated as 'intermediate elongation'.

[0122] (4) Dry heat shrinkage rate According to the standard test method of ASTM D 885, a 250 mm long specimen was left at 25°C and 65% RH for 24 hours, and then its length (L0) was measured under a load of 0.01 g / d. A load of 0.05 g / d was applied to the specimen, and it was heated to 177°C for 2 minutes, after which its length (L1) was measured. L0 and L1 were each measured five times, and the rate of change in length of the specimen {= [(L0 - L1) / L0] x 100} was expressed as the dry heat shrinkage. A (+) in the dry heat shrinkage value indicates shrinkage behavior, and a (-) indicates relaxation behavior.

[0123] [Table 1]

[0124] [Table 2]

[0125] Referring to Tables 1 and 2 above, it was confirmed that the tire cords according to the examples are environmentally friendly due to the inclusion of recycled PET, yet exhibit physical properties at the same level as the tire cords of the reference examples.

[0126] In Comparative Examples 3 and 4, although winding of the polyester drawn yarn was possible during production, a large amount of fluff and frequent yarn breakage occurred, resulting in relatively poor quality of the raw yarn. [Explanation of symbols]

[0127] 10: Tread 20: Shoulder 30: Sidewall 40: Bead 50: Belt 60: Inner liner 70: Carcass 80: Groove 90: Cap ply 101: Tires

Claims

1. A polyester drawn yarn containing 30% to 100% by weight of recycled polyethylene terephthalate having 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% relative to the total carboxylic acid component, having a tensile strength of 7.2 g / d to 7.9 g / d and an elongation at break of 15.5% to 16.6% according to the standard test method of ASTM D 885; Tire cord.

2. 2. The tire cord according to claim 1, wherein the tire cord has a tenacity utilization rate {=[(tensile strength of the tire cord) / (tensile strength of the polyester drawn yarn)]×100} of 88.5% or more.

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

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

5. 2. The tire cord according to claim 1, wherein the tire cord comprises a cord having a total fineness of 1,000 denier to 9,000 denier produced by twisting two or more of the polyester oriented yarns together in one direction, and an adhesive.

6. 2. The tire cord according to claim 1, wherein 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%.

7. 2. The tire cord according to claim 1, wherein the polyester oriented yarn has a dry heat shrinkage of 9.5% to 15.0% according to the standard test method of ASTM D 885 (specimen length 250 mm, 177°C, 2 minutes, load 0.01 g / d).

8. 2. The tire cord of claim 1, wherein the polyester drawn yarn has a total draw ratio of 1.0 to 3.0 times.

9. 2. The tire cord according to claim 1, wherein the tire cord is a two-ply yarn containing the polyester drawn yarn.

10. A tire comprising the tire cord according to claim 1.

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