KR20240027644A - Manufacturing process of thermoplastic polyurethane yarn used recycled TPU - Google Patents

Abstract

The present invention relates to a method of manufacturing thermoplastic polyurethane yarn using recycled TPU, which is a thermoplastic elastomer that can be used for the interior and exterior of industrial and household goods that has color dispersion, anti-fouling properties, scratch resistance, and molding properties that are difficult to express as a thermoplastic elastomer. As manufacturing technology has been secured, the development of eco-friendly advanced materials leading to finished fiber products with physical properties of more than 90% compared to virgin TPU is possible even when recycled TPU using scrap generated after high-frequency processing or hot melt processing is applied in the range of 20 to 50% by weight. Provides a method for manufacturing thermoplastic polyurethane yarn using possible recycled TPU.

Description

Manufacturing process of thermoplastic polyurethane yarn used recycled TPU}

The present invention relates to a method of manufacturing thermoplastic polyurethane yarn using recycled TPU. More specifically, even if recycled TPU using scrap generated after high-frequency processing or hot melt processing is applied in the range of 20 to 50% by weight, virgin TPU It is about a method of manufacturing thermoplastic polyurethane yarn using recycled TPU, which enables the development of advanced materials leading to finished fiber products with physical properties greater than 90% of that of fiber.

In general, yarns used for weaving fabrics are mainly yarns such as polyester, nylon, and acrylic resin. However, fabrics processed from these yarns not only have poor physical properties such as durability and abrasion resistance, but also have problems in various aspects such as adhesion, making them unsuitable for use in high-performance applications such as shoe fabrics.

Accordingly, in recent years, coated yarns in which thermoplastic resin has been coated on the surface of the yarn have been widely used to increase the strength of the yarn. These coated yarns are usually processed by coating thermoplastic resins such as PVC, PP or TPU on dice using a conventional extruder on yarn such as polyester or nylon.

However, when a typical thermoplastic resin is used as described above, it is difficult to control the application amount and it is difficult to apply a small amount, so there is no choice but to manufacture coated yarn with a thickness of 350 denier or more, and this also has limitations in satisfying durability and abrasion resistance. There was a difficult downside.

In response to this, thermoplastic polyurethane yarn was proposed by spinning the thermoplastic resin alone instead of coating polyester yarn with thermoplastic resin. When thermoplastic polyurethane yarn is produced on a commercial scale, it suffers from single yarn phenomenon (yarn breakage) during the spinning and stretching process. ) occurred frequently, and in particular, when trying to produce fine denier thermoplastic polyurethane yarn, there was a problem of severe single yarn phenomenon.

In Patent No. 10-1935206, developed by the present inventor to solve the single yarn phenomenon as described above, in the thermoplastic polyurethane yarn containing a thermoplastic polyurethane composition manufactured by melting and extruding thermoplastic polyurethane, the thermoplastic polyurethane composition is Contains 7 phr or less of nanosilica with a particle size of 100 nm or less; When the thermoplastic polyurethane yarn is a multifilament yarn, a single filament yarn has a denier of 50 or less, and when the thermoplastic polyurethane yarn is a monofilament yarn, a thermoplastic polyurethane yarn has been developed, characterized in that the yarn is 50 to 350 denier. As a result, a monofilament yarn has been developed. Even when continuously spinning filament yarns or multifilament yarns, the thermoplastic polyurethane yarns can be spun continuously without breaking, which has the effect of improving productivity.

However, due to the development of the above technology, thermoplastic polyurethane yarn containing nano-silica particles was able to improve the single yarn phenomenon during the manufacturing process, but color dispersion was not sufficient and shading phenomenon occurred. Even though the fabric is woven from identically manufactured yarns, color differences occur on the fabric, which is one of the biggest problems with fabric defects. In addition, since thermoplastic polyurethane yarn containing nanosilica has the risk of deteriorating antifouling properties, scratch resistance, and molding properties, there was a need to improve it to a further improved level.

Accordingly, the thermoplastic polyurethane developed in Patent No. 10-1971849 contains nanosilica with a particle size of 100 nm or less as a thickener to ensure processability and physical properties, but when the thermoplastic polyurethane yarn is a monofilament yarn, the polyurethane yarn has a particle size of 50 to 350 nm. Denier, and when the thermoplastic polyurethane yarn is a monofilament yarn, one strand of filament yarn is 50 denier or less. As a result, the thermoplastic polyurethane yarn has a hydrophobic functional group on the thermoplastic polyurethane and the surface. By containing nano-silica particles, it has excellent wear resistance and durability, and three-denier yarn can be obtained in the form of a continuous yarn without single yarn phenomenon (i.e., the phenomenon of yarn breaking during spinning or stretching). In particular, color dispersion, anti-fouling properties, Scratch resistance, molding properties, etc. have become excellent.

Meanwhile, in relation to the present invention, Patent No. 10-1341055 refers to the use of virgin thermoplastic polyurethane, scrap remaining after using it to fit the airbag pattern used in the shoe manufacturing process, or scrap remaining after processing other thermoplastic polyurethane. After collection, the thermoplastic polyurethane scrap is mixed with various additives for compounding, and then co-extruded using an extruder to produce thermoplastic polyurethane yarn, thereby improving physical properties. In particular, a composition and method for producing thermoplastic polyurethane yarns of 250 denier or less can be proposed, but in the present invention, 20 to 50% of recycled TPU using scrap generated after high-frequency processing or hot melt processing is used. We have developed a manufacturing method for thermoplastic polyurethane yarn that can be used to develop advanced materials ranging from finished fiber products with physical properties of over 90% compared to virgin TPU, even when applied to a wide range.

Republic of Korea Patent Publication No. 10-1935206 (announcement date: March 18, 2019) Republic of Korea Patent Publication No. 10-1971849 (announcement date: April 23, 2019) Republic of Korea Patent Publication No. 10-1341055 (announcement date: December 13, 2013)

The purpose of the present invention is to secure a technology for manufacturing a thermoplastic elastomer that can be used for the interior and exterior of industrial and household goods that simultaneously has color dispersion, anti-fouling properties, scratch resistance, and moldability, which are difficult to achieve with thermoplastic elastomers, thereby preventing the occurrence of heat after high-frequency processing or hot melt processing. Even if recycled TPU using recycled TPU is applied in the range of 20 to 50% by weight, the method of manufacturing thermoplastic polyurethane yarn using recycled TPU, which can develop eco-friendly advanced materials that lead to finished fiber products with physical properties of more than 90% compared to virgin TPU, is being developed. It is provided.

The method for manufacturing thermoplastic polyurethane yarn using recycled TPU according to the present invention includes a first step of grinding thermoplastic polyurethane scrap generated after high-frequency processing or hot melt processing; A second step of removing foreign substances from the pulverized thermoplastic polyurethane scrap and melt-extruding it to produce recycled thermoplastic polyurethane pellets; The recycled thermoplastic polyurethane pellets prepared above and the virgin thermoplastic polyurethane are applied at a weight ratio of 1:1 to 4 to melt and mix recycled TPU in the range of 20 to 50%, and then mixed to a size of 1 to 100 nm. A third step of producing thermoplastic polyurethane pellets by mixing and extruding hydrophobic nanosilica organically treated on the surface of nanosilica particles in the range of 0.5 to 7phr; The thermoplastic polyurethane pellets are put into a spinning extruder and melt-extruded at a temperature of 150 to 230° C., and the thread coming out through the die of the extruder is water-cooled to a temperature of 25 to 40° C. to draw the obtained thread. The yarn is aged in a heater chamber and then wound to produce thermoplastic polyurethane monofilament yarn with a fineness of 50 to 350 denier, or the thermoplastic polyurethane pellets are put into a spinning extruder and melt-extruded at a temperature of 150 to 250 ° C. , the yarn coming out through the die of the extruder is collected by the number of filaments and air cooled to 25 ~ 40 ℃, the obtained yarn is stretched, and the stretched yarn is wound to make a thermoplastic polyurethane multifilament yarn with a single yarn fineness of 50 denier / filament or less. It is characterized by a fourth manufacturing step.

According to a preferred embodiment of the present invention, the hydrophobic functional group organically treated on the surface of the nano-silica particles is at least one selected from an alkyl group, a dimethyl group, a trimethyl group, a dimethyl siloxane group, and a methacryl group, and the nano-silica particles are thermoplastic. Nanosilica aggregates with an average size of 100 to 1200 nm are formed within the polyurethane pellet.

The thermoplastic polyurethane yarn produced by the manufacturing method of the present invention is a thermoplastic elastic fiber that can be used for interior and exterior materials of industrial and household goods such as fabric for shoes and clothing, 3D printing, sensors, composite materials, matrices, etc., and is a general thermoplastic material. By securing a manufacturing technology that simultaneously possesses color dispersion, stain resistance, scratch resistance, and moldability, which are difficult to achieve with elastic materials, even if recycled TPU using scrap generated after high-frequency processing or hot melt processing is applied in the range of 20 to 50% by weight, virgin It has the effect of being able to be used as a cutting-edge eco-friendly material ranging from finished fiber products with physical properties of over 90% compared to (virgin) TPU.

Hereinafter, the manufacturing method of thermoplastic polyurethane yarn using recycled TPU according to the present invention will be described, but this is exemplified to the extent that a person skilled in the art to which the present invention pertains can easily carry out the invention. This does not mean that the technical idea and scope of the present invention are limited.

Typically, TPU (Thermoplastic Polyurethane) is used for a variety of purposes as a substitute for regulated PVC, such as shoes, interiors, and automobile interior materials. The market is expanding further due to its excellent mechanical properties, durability, and recyclability. In particular, research on a sustainable recycling process and eco-friendly dyeing process for TPU materials for shoe fabrics is urgently needed. In the present invention, pellets, monofilaments, coated yarns, and non-woven fabrics are developed using recycled shoe scraps and waste generated during the process. , securing verticalization and one-stop process technology leading to finished fabric products, as well as securing technology for expressing eco-friendly colors, were set as key themes.

Accordingly, the method for manufacturing thermoplastic polyurethane yarn using recycled TPU of the present invention includes a first step of grinding thermoplastic polyurethane scrap generated after high-frequency processing or hot melt processing; A second step of removing foreign substances from the pulverized thermoplastic polyurethane scrap and melt-extruding it to produce recycled thermoplastic polyurethane pellets; The recycled thermoplastic polyurethane pellets prepared above and the virgin thermoplastic polyurethane are applied at a weight ratio of 1:1 to 4 to melt and mix recycled TPU in the range of 20 to 50%, and then mixed to a size of 1 to 100 nm. A third step of producing thermoplastic polyurethane pellets by mixing and extruding hydrophobic nanosilica organically treated on the surface of nanosilica particles in the range of 0.5 to 7phr; The thermoplastic polyurethane pellets are put into a spinning extruder and melt-extruded at a temperature of 150 to 230° C., and the thread coming out through the die of the extruder is water-cooled to a temperature of 25 to 40° C. to draw the obtained thread. The yarn is aged in a heater chamber and then wound to produce thermoplastic polyurethane monofilament yarn with a fineness of 50 to 350 denier, or the thermoplastic polyurethane pellets are put into a spinning extruder and melt-extruded at a temperature of 150 to 250 ° C. , the yarn coming out through the die of the extruder is collected by the number of filaments and air cooled to 25 ~ 40 ℃, the obtained yarn is stretched, and the stretched yarn is wound to make a thermoplastic polyurethane multifilament yarn with a single yarn fineness of 50 denier / filament or less. It consists of the fourth stage of manufacturing.

First, the first step is a process of pulverizing thermoplastic polyurethane scrap generated after high-frequency processing or hot melt processing, specifically, airbag scrap generated after shoe processing or clear or semi-clear type thermoplastic. Polyurethane scrap is used, and in the second step, foreign substances in the pulverized thermoplastic polyurethane scrap are removed and melt-extruded to produce recycled thermoplastic polyurethane pellets.

Next, in the third step, the recycled thermoplastic polyurethane pellets and virgin thermoplastic polyurethane prepared above are applied at a weight ratio of 1: 1 to 4 to melt and mix recycled TPU in the range of 20 to 50%, and then mixed. This is a process of producing thermoplastic polyurethane pellets by mixing and extruding hydrophobic nanosilica organically treated on the surface of nanosilica particles with a size of 1 to 100 nm in the range of 0.5 to 7 phr. The virgin thermoplastic polyurethane is the raw material. It is obtained by polymerizing phosphorus polyol and isocyanate with low molecular weight glycol, which is a chain extender. Examples of polyols used here include polyester glycol, polyether glycol, and polycaprolactone, and examples of isocyanates include aromatic isocyanate and aliphatic isocyanate. etc., and examples of low molecular weight glycol include 1,4-butanediol.

At this time, the recycled thermoplastic polyurethane pellets are melt-mixed with virgin thermoplastic polyurethane, and are applied in an amount of 20 to 50% by weight based on the thermoplastic polyurethane pellets extruded from them, which is more than 90% compared to virgin TPU. It was found that it was possible to develop advanced materials that lead to finished fiber products with physical properties.

The 'nanosilica' refers to silica particles with a primary particle size of 100 nanometers (㎚) or less, which is smaller than the micro (㎛) unit, and 'nanosilica containing a hydrophobic functional group organically treated on the particle surface. ‘(Hydrophobic nanosilica)’ means that a hydrophobic organic functional group is introduced into part or all of the surface of the nanosilica particles. Conventional nano silica particles have a hydrophilic surface, but the nano silica of the present invention has excellent dispersibility because the surface becomes hydrophobic by introducing hydrophobic organic functional groups (lipophilic) through separate surface treatment (surface modification). The water resistance of the thermoplastic polyurethane yarn itself is strengthened and the tensile strength is increased.

And ‘nanosilica aggregate’, which means that several nanosilica primary particles are gathered together, refers to a state in which more than 70% of nanosilica primary particles are strongly gathered together by physical and chemical actions. These nanosilica aggregates are difficult to separate further into smaller entities (nanosilica particles) within the thermoplastic polyurethane resin for yarn use.

As above, the hydrophobic nanosilica is organically treated to include at least one hydrophobic organic functional group selected from an alkyl group, dimethyl group, trimethyl group, dimethyl siloxane group, and methacryl group on the surface of the nanosilica particle, and the nanosilica is a primary The size of the primary particle is 1 to 100 nm, and the size of the primary particle of the nanosilica refers to the particle size in a non-agglomerated state.

If the content of the hydrophobic nanosilica is less than 0.5 phr based on the thermoplastic polyurethane pellet, the effects such as water resistance and mechanical strength are minimal, and if it exceeds 7 phr, the surface of the yarn becomes opaque and there is a risk of adhesion and formability being reduced. On the other hand, if the size of the primary particles of the hydrophobic nanosilica is less than 1 nm or more than 100 nm, problems with dispersibility or cohesion may occur, of course. However, the organically treated hydrophobic nano-silica is confirmed to have improved water resistance and tensile strength by forming uniform particles or aggregates of a certain size due to the addition of organic functional groups to the particle surface, thereby improving dispersibility. did.

The thermoplastic polyurethane pellet manufactured through the third step contains nano-silica particles having a hydrophobic functional group on the particle surface. When the hydrophobic functional group is introduced to the surface of the nano-silica particles, it has the excellent durability and abrasion resistance of thermoplastic polyurethane. It has excellent mechanical strength and chemical resistance, and fabrics and molded products made from this yarn are highly durable, have excellent abrasion resistance, adhesion, color dispersion, stain resistance, scratch resistance, and moldability, and can achieve a softer, lighter texture. Therefore, it can be applied to a variety of products such as sporting goods, household goods, and industrial goods.

Hydrophobic organic functional groups that can be introduced to the surface of the nanosilica particles include alkyl groups, dimethyl groups, trimethyl groups, dimethyl siloxane groups, and methacryl groups. For example, nanosilica contained in the thermoplastic polyurethane yarn of the present invention. The particles contain dimethyl groups on the surface of the nanosilica particles by treating the nanosilica obtained by controlling the temperature and pressure in the fumed silica manufacturing process with an organosilane compound.

The nanosilica particles into which the hydrophobic organic functional group is introduced preferably have an OH group density of 1.0 OH/㎚ ³ or less. The OH group density was determined by reacting nanosilica particles into which a hydrophobic functional group was introduced with lithium aluminum hydride, and measuring the molar absorbance (ε) of the stretching vibration band of the OH group in the free silanol group at 3750 cm using IR spectroscopy. It can be verified by known methods such as measurement.

In the present invention, nanosilica particles into which hydrophobic organic functional groups are introduced exist in the form of nanosilica aggregates, and they are dispersed in the form of aggregates that are difficult to separate within the thermoplastic polyurethane for yarn coating. The nano-silica particles preferably have an average size of 100 to 1200 nm, and more preferably, the average size of the nano-silica aggregates within the thermoplastic polyurethane pellet is 200 to 500 nm.

If the size of the hydrophobic nano-silica aggregates is 100 nm or more on average, the nano-silica particles are well dispersed, but if the average size is more than 1200 nm, the thickening effect is reduced and a coating process using a T-die extruder is required. There is a risk that defects may occur. The size of the nanosilica aggregate refers to the length in the long axis direction of the nanosilica aggregate, and can be measured using a scanning electron microscope (SEM), etc.

In the final fourth step, the thermoplastic polyurethane pellets are put into a spinning extruder and melt-extruded at a temperature of 150 to 230°C, and the yarn coming out through the die of the extruder is water-cooled to a temperature of 25 to 40°C to stretch the obtained yarn. Then, the drawn yarn is aged in a heater chamber and then wound to produce a thermoplastic polyurethane monofilament yarn with a fineness of 50 to 350 denier, or the thermoplastic polyurethane pellets are put into a spinning extruder and machined at 150 to 250°C. It is melt-extruded at a high temperature, the yarns coming out through the die of the extruder are collected by the number of filaments and air-cooled at 25 to 40°C, the obtained yarn is stretched, and the stretched yarn is wound to produce a thermoplastic poly having a single yarn fineness of 50 denier/filament or less. Manufactures urethane multifilament yarn.

Thermoplastic polyurethane yarn using recycled TPU produced by the above manufacturing method includes recycled thermoplastic polyurethane and virgin thermoplastic polyurethane made from thermoplastic polyurethane scrap generated after high-frequency processing or hot melt processing. : Applied at a weight ratio of 1 to 4, recycled TPU is melt-mixed in the range of 20 to 50%, and hydrophobic nanosilica organically treated on the surface of nanosilica particles with a size of 1 to 100 nm is mixed in the range of 0.5 to 7 phr. By combining them, the purpose and effect of the present invention can be realized.

The recycled thermoplastic polyurethane is mixed at a weight ratio of 1:1 to 4 compared to virgin thermoplastic polyurethane, that is, 20 to 50% by weight of recycled thermoplastic polyurethane based on the total amount of thermoplastic polyurethane in terms of formability and product stability. Although it has been found to be the most desirable, in practice there is no strict limit to its content, which is only influenced by the quality of the recycled thermoplastic polyurethane.

In addition, in the present invention, when extruding thermoplastic polyurethane pellets mixed with the hydrophobic nanosilica, nanosilica is used in amounts of 0phr, 0.5phr, and 3phr, respectively. When comparing the viscosity change, extrusion processability, and surface condition while polymerizing at 5 phr, 7 phr, and 10 phr, the content of hydrophobic nanosilica is within 2% of the single yarn generation rate in the range of 0.5 to 7 phr and the surface condition is good, and accordingly, spinning and It was confirmed that there were no problems with stretching processability (see Patent No. 10-1971849).

Below, we specifically present a method for manufacturing thermoplastic polyurethane yarn using recycled TPU. That is, a method of manufacturing recycled thermoplastic polyurethane pellets by crushing thermoplastic polyurethane scrap generated after high-frequency processing or hot melt processing, removing foreign substances, and melt-extruding, and manufacturing thermoplastic polyurethane pellets mixed with hydrophobic nanosilica. A method for producing thermoplastic polyurethane yarn by mixing by content will be described in detail.

1. Preparation of thermoplastic polyurethane pellets

○ Step 1: The thermoplastic polyurethane scrap generated after high-frequency processing or hot melt processing was pulverized.

○ Step 2: Foreign substances in the pulverized thermoplastic polyurethane scrap were removed and melt-extruded to produce recycled thermoplastic polyurethane pellets.

○ Step 3: After melt mixing the recycled thermoplastic polyurethane pellets and virgin thermoplastic polyurethane produced above at a weight ratio of 1:1 to 4, organic treatment is applied to the surface of nano-silica particles with a size of 1 to 100 nm. The hydrophobic nanosilica was mixed in the range of 0.5 to 7 phr and extruded to prepare thermoplastic polyurethane pellets.

2. Manufacturing of thermoplastic polyurethane yarn

go. Manufacture of monofilament yarn (150 denier)

○ Step 4: Insert the thermoplastic polyurethane pellets prepared in Step 3 into a spinning extruder and melt and extrude at a temperature of 150 to 230°C (working speed: 200 m/min). The yarn coming out through the die of the extruder is water-cooled to a temperature of 25 to 40°C, the obtained yarn is drawn, the stretched yarn is aged in a heater chamber, and then wound to produce a thermoplastic polyurethane monofilament yarn with a fineness of 50 to 350 denier. was manufactured.

me. Manufacturing of multifilament yarn (50 denier/filament)

○ Step 4: The thermoplastic polyurethane pellets prepared in the third step are put into a spinning extruder and melt-extruded at a temperature of 150 to 250°C, and the threads coming out through the die of the extruder are collected by the number of filaments and 25 to 40 The yarn obtained by air cooling to ℃ was drawn, and the stretched yarn was wound to produce a thermoplastic polyurethane multifilament yarn with a single yarn fineness of 50 denier/filament or less.

In addition, the present invention has secured technology for applying appropriate additives such as Silica, CaCO ₃ , and Mg ₃ Si ₄ O ₁₀ (OH) ₂ to achieve uniform dynamic viscosity through appropriate grinding method and application of appropriate concentration of recycled raw materials. For this purpose, physical property evaluation was conducted, including appropriate production conditions such as extrusion temperature and cooling temperature, and analysis of rheological behavior and thermal properties of recycled TPU resin. First, in [Table 1] below, Physical properties were measured and evaluated according to the content of TPU scrap for each product type. At this time, products manufactured from thermoplastic polyurethane yarns used polyester polyol-based TPU with shore hardness of 65D, 75D, and 85A~95A±3, respectively.

Product type Metrics unit performance level
(virgin product) Content of TPU scrap Assessment Methods 20% 50% coating company tensile strength g/d 5≤ 5≤ 5≤ ASTM D412
G76 Tensile elongation % 10≤ 10≤ 10≤ ASTM D412
G76 monofilament tensile strength g/d 2.5≤ 2.5≤ 2.5≤ ASTM D412
G76 Tensile elongation % 80≤ 80≤ 80≤ ASTM D412
G76 melt blown
Non-woven tensile strength kgf doesn't exist 1.0≤ 1.0≤ Self-evaluation believer % doesn't exist 100≤ 100≤ Self-evaluation fabric Light resistance (QUV) - level 4 level 3 level 4 ASTM D1148
G37 Dye fastness class level 4 Level 3.5 level 4 ISO 105-E04
G4 package Permanent compression shrinkage rate % 30≥ 40≥ 30≥ ASTM D395
G16

As discussed above, the present invention commercializes thermoplastic polyurethane yarn with a recycling rate of 20% or more using TPU scrap with excellent recyclability generated after high-frequency processing or hot melt processing in order to proactively respond to the eco-friendly demands of global demand companies. For the purpose of technology development, recycling technology for scrap and yarn waste generated during the shoe or clothing manufacturing process can be secured and applied to a recycling rate of up to 50%. As a result, recycling is capable of expressing more than 90% of physical properties compared to virgin TPU. Coated yarn capable of expressing eco-friendly multi-colors by manufacturing TPU pellets, lightweight monofilament with a hollowness of 15% or more, meltblown nonwoven fabric using recycled TPU for the first time in the world, package products for shoes and clothing, etc. Manufacturing technology was established.

Claims (3)

A first step of pulverizing thermoplastic polyurethane scrap generated after high-frequency processing or hot melt processing;
A second step of removing foreign substances from the pulverized thermoplastic polyurethane scrap and melt-extruding it to produce recycled thermoplastic polyurethane pellets;
The recycled thermoplastic polyurethane pellets prepared above and the virgin thermoplastic polyurethane are applied at a weight ratio of 1:1 to 4 to melt and mix recycled TPU in the range of 20 to 50%, and then mixed to a size of 1 to 100 nm. Thermoplastic polyurethane pellets are prepared by mixing 0.5 to 7 phr of hydrophobic nano-silica organically treated with one or more types selected from alkyl groups, dimethyl groups, trimethyl groups, dimethyl siloxane groups, and methacryl groups on the surface of nano-silica particles and extruding them. The third step is to do;
The thermoplastic polyurethane pellets are put into a spinning extruder and melt-extruded at a temperature of 150 to 230° C., and the thread coming out through the die of the extruder is water-cooled to a temperature of 25 to 40° C. to draw the obtained thread. A fourth step of maturing the yarn in a heater chamber and then winding it to produce thermoplastic polyurethane monofilament yarn with a fineness of 50 to 350 denier;
A method of manufacturing thermoplastic polyurethane yarn using recycled TPU, characterized in that it consists of. A first step of pulverizing thermoplastic polyurethane scrap generated after high-frequency processing or hot melt processing;
A second step of removing foreign substances from the pulverized thermoplastic polyurethane scrap and melt-extruding it to produce recycled thermoplastic polyurethane pellets;
The recycled thermoplastic polyurethane pellets prepared above and the virgin thermoplastic polyurethane are applied at a weight ratio of 1:1 to 4 to melt and mix recycled TPU in the range of 20 to 50%, and then mixed to a size of 1 to 100 nm. Thermoplastic polyurethane pellets are prepared by mixing 0.5 to 7 phr of hydrophobic nano-silica organically treated with one or more types selected from alkyl groups, dimethyl groups, trimethyl groups, dimethyl siloxane groups, and methacryl groups on the surface of nano-silica particles and extruding them. The third step is to do;
The thermoplastic polyurethane pellets are put into a spinning extruder and melt-extruded at a temperature of 150 to 250°C. The threads coming out through the die of the extruder are collected by the number of filaments and air-cooled to 25 to 40°C to draw the obtained thread, A fourth step of manufacturing a thermoplastic polyurethane multifilament yarn having a single yarn fineness of 50 denier/filament or less by winding the drawn yarn;
A method of manufacturing yarn using recycled TPU, characterized in that it consists of. According to any one of paragraphs 1 and 2,
The nano-silica particles are characterized in that they form nano-silica aggregates with an average size of 100 to 1200 nm within the thermoplastic polyurethane pellet. A method of manufacturing thermoplastic polyurethane yarn using recycled TPU.