Recycled polyethylene terephthalate yarn and recycled polyethylene terephthalate tire cord

Abstract

The method for producing recycled polyethylene terephthalate yarn according to the present invention includes the steps of melting recycled polyethylene terephthalate chips and spinning them through a spinning nozzle to produce a spun yarn, and multi-stage drawing and winding the spun yarn using equipment with five or more stages of drawing godet rollers, wherein the recycled polyethylene terephthalate chips contain 1.0 mol% or less of isophthalic acid, the draw ratio is 1.5 to 2.45, and the speed of the fourth godet roller among the five or more stages of drawing godet rollers is 5500 m / min to 7000 m / min. The recycled polyethylene terephthalate yarn produced by this method has a strength of 8.5 g / d or more and a dimensional stability ES of 11.0% or less.

Description

[Technical Field]

[0001] The present invention relates to a recycled polyethylene terephthalate yarn and a recycled polyethylene terephthalate tire cord. [Background technology]

[0002] Since the beginning of the 20th century, humankind has pursued production efficiency by introducing mass production methods under the leadership of developed countries, and the rapid pace of industrialization has ushered in an era of mass production and symmetrical consumption. While this has dramatically increased the convenience of our lives, it has also led to the emergence of environmental problems due to the deterioration of the global environment.

[0003] Among synthetic resins, polyethylene terephthalate (PET) has excellent chemical stability and is therefore mass-produced and widely used in a variety of industrial fields. However, the disposal of PET waste, which is being generated in large quantities as the production and use of PET increases, is currently a major social issue. In particular, the disposal of PET bottles (PET bottles), which have a large volume relative to their weight, is becoming an increasingly serious problem.

[0004] Therefore, countries in Europe and the US are adapting to changes in the external environment (tighter regulations, environmental groups, and proactive responses to climate change) and applying recycled polyethylene terephthalate to various industries. Demand is also emerging for products using recycled polyethylene terephthalate in the tire and tire cord market.

[0005] However, tire cords made from recycled polyethylene terephthalate have problems such as poor moldability compared to tire cords made from virgin polyethylene terephthalate, and poor physical properties such as impact resistance and heat resistance, as well as poor appearance, which reduces their marketability.

[0006] Therefore, there is a need for a technology that uses recycled polyethylene terephthalate and is environmentally friendly while minimizing the deterioration of physical properties. [Prior art documents] [Patent documents]

[0007] [Patent Document 1] KR 10-2011-0026707 A Summary of the Invention [Problem to be solved by the invention]

[0008] An object of the present invention is to provide a recycled polyethylene terephthalate yarn and a tire cord using the same, which are environmentally friendly because they use recycled polyethylene terephthalate and have minimal deterioration in physical properties compared to when virgin polyethylene terephthalate is used. [Means for solving the problem]

[0009] The method for producing recycled polyethylene terephthalate yarn according to the present invention includes the steps of melting recycled polyethylene terephthalate chips and spinning them through a spinning nozzle to produce a spun yarn, and multi-stage drawing and winding the spun yarn in equipment using five or more stages of drawing godet rollers, wherein the recycled polyethylene terephthalate chips contain 1.0 mol% or less of isophthalic acid, the draw ratio is 1.5 to 2.45, and the speed of the fourth godet roller among the five or more stages of drawing godet rollers is 5500 m / min to 7000 m / min.

[0010] The recycled polyethylene terephthalate chip yarn according to the present invention can have a strength of 8.5 g / d or more and a shape stability ES of 11.0% or less.

[0011] The recycled polyethylene terephthalate chip yarn according to the present invention may have a crystallinity of 40.0% or more.

[0012] The recycled polyethylene terephthalate chip yarn according to the present invention may have a crystal size of 40.0 Å or more in the Miller index (010) crystal plane.

[0013] The recycled polyethylene terephthalate tire cord according to the present invention is produced by a production method including the steps of twisting the recycled polyethylene terephthalate yarn to produce a raw cord, weaving the raw cord to produce a woven fabric, and immersing the woven fabric in a dipping liquid, and has a strength of 6.5 g / d or more and a shape stability ES of 6.3% or less.

[0014] The recycled polyethylene terephthalate tire cord according to the present invention can have a tenacity utilization rate of 80% or more and a fatigue resistance of 75% or more. [Effects of the Invention]

[0015] The recycled polyethylene terephthalate yarn and recycled polyethylene terephthalate tire cord according to the present invention are environmentally friendly and have excellent physical properties. [Brief explanation of the drawings]

[0016] [Figure 1] FIG. 1 is a diagram showing an apparatus for carrying out spinning, multi-stage drawing, and winding processes of recycled polyethylene terephthalate yarn according to one embodiment of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0017] The present invention will be described in detail below.

[0018] As used herein, "recycled polyethylene terephthalate" refers to polyethylene terephthalate that has been recycled for recycling purposes after being discarded after being used for a specific purpose, such as a container, fiber, tire cord, etc. As used herein, recycled polyethylene terephthalate may be mechanically recycled polyethylene terephthalate and / or chemically recycled polyethylene terephthalate.

[0019] In this specification, "virgin polyethylene terephthalate" is distinguished from the above-mentioned "recycled polyethylene terephthalate" and means polyethylene terephthalate that has not been recycled.

[0020] Isophthalic acid is an isomer of terephthalic acid, and recycled polyethylene terephthalate generally contains isophthalic acid. In particular, polyethylene terephthalate used in plastic bottles contains isophthalic acid for easier processing, and recycled polyethylene terephthalate made by recycling this contains 1 to 5 mol% of isophthalic acid.

[0021] Since isophthalic acid suppresses the crystallinity and crystal size during the production of yarn, yarns produced using polyethylene terephthalate containing isophthalic acid have low strength and thermal stability, which results in a decrease in tenacity during the tire cord production process, making such yarns undesirable for tire cord production.

[0022] In order to produce a yarn with the same strength as virgin polyethylene terephthalate using recycled polyethylene terephthalate containing isophthalic acid, the draw ratio should be increased.

[0023] However, increasing the draw ratio breaks the tie chains that connect the crystalline and amorphous regions, resulting in a decline in the yarn's physical properties, such as a decrease in the yarn's strength utilization rate and fatigue resistance. In addition, increasing the draw ratio promotes the orientation of the amorphous regions, increasing the yarn's thermal shrinkage rate, which can cause uneven shrinkage during post-processing.

[0024] The present inventors have discovered that the use of recycled polyethylene terephthalate chips having an isophthalic acid content of 1.0 mol % or less makes it possible to reduce the draw ratio compared to conventional methods.

[0025] In addition, the inventors have discovered that yarns and tire cords produced using recycled polyethylene terephthalate chips with an isophthalic acid content of 1.0 mol% or less and at a draw ratio of 1.5 to 2.45 have similar physical properties to yarns and tire cords produced using virgin polyethylene terephthalate chips.

[0026] Manufacturing of recycled polyethylene terephthalate yarn Recycled polyethylene terephthalate chips containing 1.0 mol% or less of isophthalic acid are melted and spun through a spinning nozzle to produce a spun yarn, and the spun yarn is then multi-stage drawn and wound up in equipment using five or more stages of drawing godet rollers to produce a recycled polyethylene terephthalate raw yarn.

[0027] In this case, the recycled polyethylene terephthalate chips preferably contain 1.0 mol% or less of isophthalic acid, more preferably 0.5 mol% or less, and most preferably 0.4 mol% or less, or may be isophthalic acid-free. If the recycled polyethylene terephthalate chips contain more than 1.0 mol%, the increase in crystallinity and crystal size during yarn production may be suppressed, resulting in reduced strength and thermal stability of the yarn and reduced tenacity during the tire cord production process. On the other hand, the recycled polyethylene terephthalate chips may be isophthalic acid-free, and in this case, the recycled polyethylene terephthalate chips may be, for example, chemically recycled polyethylene terephthalate chips. However, this is not limited to this.

[0028] First, referring to Figure 1, recycled polyethylene terephthalate chips are melted at a temperature of 285°C in an extruder 1 and extruded through a gear pump 2 and a spinning nozzle 3 to produce a spun yarn. The spun yarn is then passed through a cooling section 5 to be solidified.

[0029] In the present invention, it is preferable to use a spinning filter of 300 to 600 mesh during spinning, in order to remove foreign matter and impurities remaining in the regeneration process of recycled polyester chips and to create a uniform pressure on the chips remaining in the pack, thereby making the fineness of the multifilaments uniform.

[0030] Meanwhile, the spun yarn may pass through the heating device 4 before passing through the cooling zone 5, if necessary. The zone where the heating device 4 is installed is called the delayed cooling zone or heating zone, and this zone has a length of 100 mm to 600 mm and a temperature (air-contact surface temperature) of 300°C to 380°C.

[0031] In the cooling zone 5, the cooling air may be blown in by, but not limited to, an open quenching method, a circular closed quenching method, a radial outflow quenching method, and a radial inflow quenching method.

[0032] In this case, the temperature of the cooling air injected into the cooling zone 5 for rapid cooling is adjusted to 20°C to 50°C. This rapid cooling using a sudden temperature difference between the hood and the cooling zone 5 increases the solidification point and spinning tension of the spun polymer, and increases the orientation of the spun yarn and the formation of connecting chains between crystals. If the temperature of the cooling air is below 20°C or above 50°C, fusion between the spun yarns may occur, ultimately resulting in a deterioration in the physical properties and appearance quality of the yarn.

[0033] Next, the spun yarn solidified while passing through the cooling zone 5 reduces the coefficient of friction in a short time and can be oiled at 0.5% to 1.5% by weight of the spun yarn by passing through the emulsion sharing device 12, which applies an emulsion with excellent stretchability and thermal efficiency.

[0034] The oiled spun yarn may be passed through a first godet roller 6 to form an undrawn yarn.

[0035] In this case, the speed of the first godet roller 6 is preferably 2,200 m / min to 4,500 m / min. If the speed of the first godet roller 6 is less than 2,200 m / min, the cross-sectional uniformity of the yarn may be poor, resulting in poor drawing workability. The degree of orientation of the undrawn yarn may be reduced, resulting in a low crystallinity and poor development of crystalline portions. This may result in poor thermal stability during drawing and dipping, reducing the strength of the tire cord. Furthermore, if high drawing is performed to improve tenacity and modulus, shape stability may be reduced. Furthermore, if the speed of the first godet roller 6 exceeds 4,500 m / min, the drawability of the undrawn yarn may be reduced, resulting in poor yarn strength and drawing workability.

[0036] The recycled polyethylene terephthalate yarn of the present invention is produced by passing the spun yarn through five-stage drawing godet rollers 6, 7, 8, 9, and 10, hot drawing it in multiple stages, and winding it up. While Fig. 1 shows five godet rollers, 6, 7, 8, 9, and 10, the number of godet rollers is not limited to this and may include godet rollers with five or more stages.

[0037] The speed of the first godet roller 6 may be 2200 m / min to 4500 m / min, the speed of the second godet roller 7 may be 1.1 to 1.4 times the speed of the first godet roller 6, and the speed of the third godet roller 8 may be 1.1 to 1.3 times the speed of the second godet roller 7.

[0038] The speed of the fourth godet roller 9 is 5500 m / min to 7000 m / min. When the speed of the fourth godet roller 9 is 5500 m / min to 7000 m / min, the undrawn orientation can be increased, thereby increasing the modulus and improving the dimensional stability even if the strength of the raw yarn is similar.

[0039] The speed of the fifth godet roller 10 may be 50 m / min to 150 m / min lower than the speed of the fourth godet roller 9 .

[0040] In the multi-stage hot drawing process, the temperature of the godet roller is preferably 40° C. to 240° C. If the temperature of the godet roller is less than 40° C., problems may occur in achieving high strength properties through cold drawing, while if the temperature exceeds 240° C., problems may occur in that the multifilaments are fused together due to proximity to the melting point of the resin, resulting in single filament breakage, which may result in poor appearance of the raw yarn or complete filament breakage.

[0041] In one embodiment, the draw ratio of the recycled polyethylene terephthalate yarn may be 2.45 or less. The draw ratio is preferably 2.4 or less, and most preferably 2.35 or less. If the draw ratio exceeds 2.45, the tie chains connecting the crystalline and amorphous regions may be broken, resulting in a decrease in the strength utilization rate and fatigue resistance of the yarn, and the orientation of the amorphous regions may develop, increasing the thermal shrinkage rate of the yarn and causing uneven shrinkage during post-processing. In another embodiment, the draw ratio of the recycled polyethylene terephthalate yarn may be 1.5 or more. If the draw ratio is less than 1.5, productivity may decrease and the strength and dimensional stability of the yarn and cord may decrease.

[0042] The draw ratio is the ratio of the fastest speed to the slowest speed of the godet rollers in the multi-stage drawing process. In one embodiment, the fourth godet roller 9 may be the fastest and the first godet roller 6 may be the slowest, and the draw ratio in this case may be the speed of the fourth godet roller 9 / the speed of the first godet roller 6. After the drawing process, recycled polyethylene terephthalate yarn is produced using a conventional winding method.

[0043] The speed of the winding roller 11 is preferably 5000 m / min to 6500 m / min. If the speed of the winding roller 11 is less than 5000 m / min, productivity may decrease, and if the speed of the winding roller 11 exceeds 6500 min, yarn breakage may occur during winding, reducing workability.

[0044] The recycled polyethylene terephthalate yarn according to the present invention produced by the above-described method may have a crystallinity of 40.0% or more, a crystal size of the (010) crystal plane of 40.0 Å or more, a strength of 8.5 g / d or more, and a dimensional stability ES of 11.0% or less, and may have physical properties similar to those of virgin polyethylene terephthalate yarn. In a preferred embodiment, the recycled polyethylene terephthalate yarn according to the present invention may have a crystallinity of 40.0% to 60.0%, a crystal size of the (010) crystal plane of 40.0 Å to 60.0 Å, a strength of 8.5 g / d to 12.0 g / d, and a dimensional stability ES of 6.0% to 11.0%.

[0045] This is because the breakage of tie chains and the orientation of non-crystalline regions in the recycled polyethylene terephthalate yarn according to the present invention are smaller than those in conventional recycled polyethylene terephthalate yarns.

[0046] Manufacturing recycled polyethylene terephthalate tire cord A raw cord for tire cord is produced by twisting recycled polyethylene terephthalate raw yarn, the raw cord is woven to produce a woven fabric, and the woven fabric is immersed in a dipping solution to produce a recycled polyethylene terephthalate tire cord.

[0047] A raw cord is manufactured by twisting recycled polyethylene terephthalate yarn. Specifically, the recycled polyethylene terephthalate yarn is first ply twisted and then top twisted to manufacture a raw cord. In this case, the top twist and bottom twist are generally the same number of twists (twist level), or different numbers of twists can be added as needed.

[0048] In the present invention, the twist number for the top twist and the ply twist may be the same, ranging from 300 / 300 Twists Per Meter (TPM) to 500 / 500 TPM. When the top twist and the ply twist are the same, the raw cord produced tends to maintain a straight line without twisting or rotation, maximizing the expression of physical properties. If the twist number for the top twist and the ply twist is less than 300 / 300 TPM, the raw cord's break elongation is reduced and fatigue resistance is likely to decrease. If the twist number exceeds 500 / 500 TPM, the strength is significantly reduced, making the cord unsuitable for use as a tire cord.

[0049] The produced raw cord is woven using a weaving machine, and the obtained woven fabric is immersed in a dipping solution and then strengthened to produce a tire cord having a resin layer attached to the surface of the raw cord.

[0050] Dipping is a process to improve the drawback of tire cord fibers, which is their poor adhesion to rubber. As mentioned above, the fabric is immersed in a dipping solution to impregnate the surface of the fiber with a layer of RFL (Resorcinol formaldehyde latex) resin.

[0051] First, the fabric is immersed in an epoxy resin and RFL adhesive solution, dried in a dry area at 120°C to 220°C and a stretch of 2.0% to 6.0% for 100 to 200 seconds, and then heat-set in a high temperature area at 220°C to 270°C and a stretch of 1.0% to 5.0% for 100 to 200 seconds.

[0052] Next, the substrate is again immersed in an adhesive solution prepared as follows: The adhesive solution prepared as follows is merely an example.

[0053] A solution containing 45.6 parts by weight of 29.4 wt% resorcinol, 255.5 parts by weight of pure water, 20 parts by weight of 37% formalin, and 3.8 parts by weight of 10 wt% sodium hydroxide is prepared, and after stirring and reacting for 5 hours at 25°C, 300 parts by weight of 40 wt% VP-latex, 129 parts by weight of pure water, and 23.8 parts by weight of 28% ammonia water are added and aged for 20 hours at 25°C, and an adhesive liquid can be prepared with a solid content concentration of 19.05%.

[0054] After immersion in the adhesive, the fabric is dried for 50 to 150 seconds at 120 to 220°C and under a stretch of 0 to 3%. The adhesive coverage is preferably 2 to 7% of the fabric weight based on solids. To adjust the adhesive coverage, a stretch of 0 to 3%, and more preferably 1 to 2%, is applied during drying. If the stretch exceeds 3%, the adhesive coverage (DPU) can be adjusted, but the slit elongation decreases, resulting in reduced fatigue resistance. If the stretch is reduced to less than 0%, the dipping solution may penetrate into the fabric, making it impossible to adjust the DPU.

[0055] After drying, the cord is heat-set for 20 to 60 seconds at 220 to 270°C and a stretch of 3 to 6%. If the heat-set time is less than 20 seconds, the adhesive will not have enough time to react, resulting in a decrease in adhesive strength. If the heat-set time is longer than 60 seconds, the adhesive will become too hard, resulting in a decrease in fatigue resistance of the cord.

[0056] Although the present invention is mainly described in terms of dipping using a two-bath dipping machine, a person having ordinary knowledge in the art should be able to perform heat treatment under the same conditions using a one-bath dipping machine.

[0057] The recycled polyethylene terephthalate tire cord according to the present invention produced by the above-described method may have a strength of 6.5 g / d or more, a tenacity utilization rate of 80% or more, a dimensional stability ES of 6.3% or less, and a fatigue resistance of 75% or more, and may have physical properties at a level similar to that of virgin polyethylene terephthalate tire cord.

[0058] The present invention will be described below with reference to examples and comparative examples. The following examples are provided to explain the present invention in detail, but the scope of the present invention is not limited to the following examples.

[0059] Examples and Comparative Examples Example 1 Recycled polyethylene terephthalate chips not containing isophthalic acid were melted and spun through a nozzle to produce a spun yarn, which was then multistage-drawn under the drawing conditions in Table 1 below and wound up to produce a raw yarn.

[0060] Two of the produced yarns were twisted at 370 TPM to produce a raw cord, which was then woven into a woven fabric. The woven fabric was immersed in epoxy resin and RFL, dried in a dry area at 170°C and 4.0% stretch for 150 seconds, heat-set in a high-temperature area at 245°C and 3.0% stretch for 150 seconds, and then immersed in an adhesive solution prepared as follows, dried at 170°C and 1.5% stretch for 100 seconds, and dry-heat-set at 245°C and 4.5% stretch for 40 seconds to produce a tire cord.

[0061] <Preparation of adhesive solution> A solution containing 45.6 parts by weight of 29.4 wt% resorcinol, 255.5 parts by weight of pure water, 20 parts by weight of 37% formalin, and 3.8 parts by weight of 10 wt% sodium hydroxide was prepared and stirred at 25°C for 5 hours to allow the reaction to proceed. After that, 300 parts by weight of 40 wt% VP-latex, 129 parts by weight of pure water, and 23.8 parts by weight of 28% ammonia water were added and the mixture was aged at 25°C for 20 hours, maintaining the solids concentration at 19.05% to prepare an adhesive solution.

[0062] Example 2, Example 3, and Comparative Examples 2 and 3 The yarns and tire cords of Examples 2, 3, and Comparative Examples 2 and 3 were produced in the same manner as in Example 1, except that the content of isophthalic acid in the recycled polyethylene terephthalate chips and the drawing conditions were varied.

[0063] Comparative Example 1 A raw yarn and a tire cord were produced in the same manner as in Example 1, except that virgin polyethylene terephthalate chips were used instead of recycled polyethylene terephthalate chips.

[0064] Experimental Example - Properties of Raw Yarn and Tire Cord The physical properties of the yarns and tire cords of the Examples and Comparative Examples were measured by the following methods, and the measurement results are shown in Table 1 below.

[0065] 1) Crystallinity % It is measured by the density method using a density gradient tube. The density of the crystalline region is ρ c , the density of the amorphous region is ρ a If the density of the sample is ρ, the crystallinity (X) is calculated using the following formula: X(%)=(ρ c -ρ) / (ρ c -ρ a ) x 100

[0066] 2) Crystal size Using an X-ray with a wavelength of λ-1.5428Å, wide-angle X-ray diffraction analysis was performed, and the (010) diffraction peak was analyzed from the obtained diffraction pattern, and the crystal size CS was calculated using the following formula.

[0067] Crystal size = (kλ) / (β cosθ) K: Scherrer constant λ:X-Ray wavelength (1.5428Å) β: Half width θ: Bragg angle

[0068] 3) Power and strength After leaving the raw yarn and cord at 25°C and a relative humidity of 65% for 24 hours, the specimens were measured using a tensile tester according to the method of ASTM D885.

[0069] 4) Elongation at specific load (E) In the case of raw yarn, it means the elongation at a load of 4.5 g / d in the elongation load curve obtained using an Instron slow-elongation tensile tester according to the method of ASTM D885.

[0070] In the case of cord, it means the elongation at a load of 2.25 g / d in the elongation load curve obtained using an Instron slow-speed elongation tensile tester according to the method of ASTM D885.

[0071] 5) Dry heat shrinkage (Shrinkage, S) The raw yarn and cord were left at 20°C and a relative humidity of 65% for 24 hours, and then the dry heat shrinkage was calculated as the ratio of the length L0 measured at a constant load of 0.05 g / d using Testrite to the length L1 after treatment at 177°C for 2 minutes at a constant load of 0.05 g / d. S(%)={(L0-L1) / LO}*100

[0072] 6) Shape stability ES Shape stability ES = intermediate elongation + dry heat shrinkage rate In addition to the method for measuring the shape stability, the meaning of the shape stability will be explained in detail below.

[0073] Generally, when a tire is vulcanized, the shrinkage rate and intermediate elongation of the cord change. The sum of the shrinkage rate and intermediate elongation is considered to be similar to the concept of modulus of the cord after the tire is completely manufactured.

[0074] In other words, there is a correlation between a lower ES value and a higher modulus. If the modulus is high, the tire generates more force due to deformation, making it easier to handle. Conversely, it can generate the same amount of tension with less deformation, improving handling performance and indicating excellent shape stability due to deformation. Therefore, the ES value is used as a physical property to determine the excellence of cord performance when manufacturing tires.

[0075] In addition, when manufacturing tires, tires with a low ES value have less deformation due to heat, which has the effect of improving tire uniformity, and therefore improving the uniformity of the entire tire. Therefore, tires using cords with a low ES value have the effect of improving tire uniformity compared to tires using cords with a high ES value, which can also improve tire performance.

[0076] 7) Strong utilization rate Tenacity utilization rate (%) = cord strength / (strength of raw yarn * number of plies) * 100

[0077] 8) Fatigue resistance The strength after the fatigue test was measured using a belt fatigue tester, and the strength was divided by the strength before the fatigue test to determine the fatigue resistance.

[0078] The fatigue test conditions were a load of 80 kgf, a spindle radius of 12.7 mm, and a belt fatigue cycle of 37,500.

[0079] Fatigue resistance (%) = Strength after fatigue test / Strength before fatigue test * 100

[0080] [Table 1]

[0081] It can be seen that the physical properties of the yarn and tire cord of Examples 1 to 3, which contain 1.0 mol % or less of isophthalic acid and have a draw ratio of 2.45 or less, are almost similar to the physical properties of the yarn and tire cord of Comparative Example 1. On the other hand, it can be seen that the physical properties of the yarn and tire cord of Comparative Examples 2 and 3, which contain more than 1.0 mol % of isophthalic acid, are inferior to Examples 1 to 3 and Comparative Example 1.

[0082] Because the present invention may be modified in various ways and may have various forms, it should be understood that the invention is not limited to the particular forms disclosed, but includes all modifications, equivalents, and alternatives falling within the spirit and scope of the invention. [Explanation of symbols]

[0083] 1: Extruder 2: Gear pump 3: Spinning nozzle 4:Heating device 5: Cooling area 6: 1st Godet Roller GR1 7: 2nd Godet Roller GR2 8: 3rd Godet Roller GR3 9: 4th Godet Roller GR4 10: 5th Godet Roller GR5 11: Winding roller 12: Emulsion supply device

Claims

1. Melting the recycled polyethylene terephthalate chips and spinning them through a spinning nozzle to produce a spun yarn; and multi-stage drawing and winding the spun yarn in equipment using five or more stages of drawing godet rollers; The recycled polyethylene terephthalate chips contain 1.0 mol% or less of isophthalic acid, The draw ratio is 1.5 to 2.45, A method for producing recycled polyethylene terephthalate yarn, characterized in that the speed of the fourth godet roller among the five or more stages of drawing godet rollers is 5,500 m / min to 7,000 m / min.

2. Produced by the production method according to claim 1, Strength is 8.5g / d or more, A recycled polyethylene terephthalate yarn characterized by having a shape stability E-S of 11.0% or less.

3. The recycled polyethylene terephthalate yarn according to claim 2, characterized in that the crystallinity is 40.0% or more.

4. The recycled polyethylene terephthalate yarn according to claim 2, characterized in that the crystal size of the Miller index (010) crystal plane is 40.0 Å or more.

5. A step of twisting the recycled polyethylene terephthalate raw yarn according to any one of claims 2 to 4 to produce a raw cord; weaving the raw cord to produce a woven fabric; and immersing the fabric in a dipping liquid, Strength is 6.5g / d or more, A recycled polyethylene terephthalate tire cord characterized by having a shape stability E-S of 6.3% or less.

6. The power utilization rate is over 80%. The recycled polyethylene terephthalate tire cord according to claim 5, characterized in that it has a fatigue resistance of 75% or more.

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