Material recycled nylon 66 fiber

Abstract

A regenerated nylon 66 fiber characterized by containing 5% by weight or more of regenerated nylon 66, having a total fineness of 110-2100 dtex, a strength of 7.6-10.0 cN / dtex, and an elongation of 15.0-35.0%. A material, regenerated nylon 66 fiber, having high strength and good hair quality is provided.

Description

Technical Field

[0001] This invention relates to nylon 66 fibers using polyhexamethylene adipamide resin that has undergone material recycling, and a method for manufacturing the same. Background Technology

[0002] Nylon 6 and Nylon 66 multifilaments have higher tensile strength and elongation and better hair quality compared with general multifilaments such as polyester and polypropylene. Therefore, they are used in many industrial applications such as airbags, tire cords, tennis racket strings, ropes, fishing nets, and bag straps.

[0003] Furthermore, due to increased environmental awareness in recent years, the value of products using environmentally friendly raw materials, such as recycled materials, has increased, leading to a demand for the development of fibers that utilize recycled materials.

[0004] Regarding nylon 6 and polyester, the materials can be recycled relatively easily. As disclosed in Patent Documents 1 and 2 below, methods for manufacturing recycled fibers with properties almost identical to those of virgin fibers are presented.

[0005] Patent Document 3 discloses a method for manufacturing recycled nylon resin granules by pulverizing nylon waste materials, including nylon 66 full-glossy nylon 66 semi-glossy nylon 66 matte nylon 66, nylon 66 ultra-high strength nylon 66, nylon 66 high strength nylon 66, nylon 66 fine denier high strength nylon 66, nylon 66 fishing net waste line, and nylon 66 waste fabric. The granules are then washed to reduce the oil content to 0.22% by weight, followed by dehydration and melt granulation. The recycled nylon granules are then melt-spun to produce recycled nylon fibers. However, Patent Document 3 describes a stretching process in the fiber manufacturing process where the stretching ratio is set to 1.2 to 1.5 times. If it exceeds 1.5 times, the excessive stretching causes the nylon to break easily, thus clearly failing to achieve the strength level required for industrial fibers.

[0006] Existing technical documents

[0007] Patent documents

[0008] Patent Document 1: International Publication No. 2022 / 196407

[0009] Patent Document 2: Japanese Patent Application Publication No. 2003-13328

[0010] Patent Document 3: Japanese Patent No. 6629943 Summary of the Invention

[0011] The problem that the invention aims to solve

[0012] However, compared to other polymers, Nylon 66 is prone to thermal / oxidative degradation, gelation, and is difficult to regenerate, which are problems.

[0013] The purpose of this invention is to solve the above-mentioned problems, suppress polymer degradation caused by heat / oxidation, and obtain recycled nylon 66 fibers with the same tensile strength and hairiness as virgin 100% nylon 66 fibers.

[0014] Methods for solving problems

[0015] The present invention has been thoroughly researched to solve the above-mentioned problems and includes the following structure.

[0016] (1) A recycled nylon 66 fiber, characterized in that it contains more than 5% by weight of recycled nylon 66 resin, has a total fineness of 110 to 2100 dtex, a strength of 7.6 to 10.0 cN / dtex, and an elongation of 15.0 to 35.0%.

[0017] (2) The regenerated nylon 66 fiber according to (1) above is characterized in that the UVA value at a wavelength of 290 nm at a solution concentration of 5 mg / mL is less than 0.30.

[0018] (3) The regenerated nylon 66 fiber according to (1) or (2) above is characterized in that the number of hairs is 0 to 3 per 10,000 meters.

[0019] (4) The recycled nylon 66 fiber according to any one of (1) to (3) above is manufactured from granules made from any one or more of the following raw materials: waste from fiber manufacturing process, waste from the edge of airbag base fabric, waste from base fabric during scouring, waste from defective airbags, waste from airbag cutting and sewing, and waste vehicle recycled airbags.

[0020] (5) A fabric for airbags, characterized in that it uses the recycled nylon 66 fiber described in (1) or (2) above.

[0021] (6) A tire cord, characterized in that it uses the recycled nylon 66 fiber described in (1) or (2) above.

[0022] (7) A racket string, characterized in that it uses the recycled nylon 66 fiber described in (1) or (2) above.

[0023] (8) A multi-wedge belt, characterized in that it uses the recycled nylon 66 fiber described in (1) or (2) above.

[0024] (9) A fabric for bags, characterized in that it uses the recycled nylon 66 fiber described in (1) or (2) above.

[0025] The effects of the invention

[0026] Through this invention, it is possible to obtain recycled nylon 66 fiber with the same tensile strength and elongation properties as virgin 100% nylon 66 fiber, as well as good hair quality. Attached Figure Description

[0027] Figure 1 This is a schematic diagram of the manufacturing process of recycled nylon 66 fiber, the material of this invention. Detailed Implementation

[0028] The present invention will now be described in detail.

[0029] The recycled nylon 66 fibers involved in the embodiments of the present invention are preferably nylon 66 fibers in which 5% by weight or more of recycled polyhexamethylene adipamide resin is blended. That is, the recycled nylon 66 fibers of the present invention contain 5% by weight or more of recycled polyhexamethylene adipamide resin. From the perspective of the increasing awareness of environmental protection in recent years, the higher the blending amount, the better; preferably, nylon 66 fibers in which 20% to 100% by weight of recycled polyhexamethylene adipamide resin is blended are preferred.

[0030] In the polyhexamethylene adipamide resin, other copolymer components, for example, less than 10 mol%, may be included without impairing the effects of the present invention. However, by including a large amount of hexamethylene adipamide units, the regularity of the molecular chains of the resulting fibers is improved, making them easier to orient and crystallize during the fiber-making process, thus resulting in fibers with excellent mechanical properties, which is therefore preferred. More preferably, the hexamethylene adipamide units are 95 mol% or more, and even more preferably 98 mol% or more.

[0031] The recycled nylon 66 fiber of the present invention may, as needed, contain end-capping agents such as monocarboxylic acids, matting agents such as titanium dioxide, polymerization catalysts such as phosphorus compounds, heat-resistant agents, antioxidants such as copper compounds and alkali metal or alkaline earth metal halides, and heat-resistant stabilizers as components other than nylon. However, the nylon content is preferably 95% by weight or more, more preferably 97% by weight or more. When the nylon content is less than 95% by weight, the heat resistance of the nylon decreases, which is therefore undesirable.

[0032] The total fineness of the recycled nylon 66 fibers of the present invention is 110 to 2100 dtex, more preferably in the range of 350 to 2100 dtex. If the fineness is less than 110 dtex, the fineness is too fine and therefore cannot withstand mechanical stretching at high ratios to achieve high strength, increasing the likelihood of fuzzing. When the fineness exceeds 2100 dtex, cooling efficiency decreases and mechanical properties deteriorate, making it undesirable. Furthermore, the fineness of individual fibers is preferably 2 to 35 dtex. If the fineness of individual fibers is 2 to 35 dtex, high-strength recycled 66 fibers can be stably obtained while maintaining quality. There is no particular requirement for the number of monofilaments; the fineness of individual fibers is important.

[0033] The recycled nylon 66 fiber of the present invention has a strength of 7.6 to 10.0 cN / dtex. Preferably, it is 8.0 to 9.7 cN / dtex, more preferably 8.5 to 9.7 cN / dtex. If the strength is within this range, it becomes a nylon fiber suitable for industrial materials such as airbags, and for clothing fabrics with excellent durability. If the strength is less than 7.6 cN / dtex, it is insufficient for improving the durability of fibers used in industrial materials such as airbags. In the case of obtaining nylon fibers with a strength exceeding 10.0 cN / dtex, high-ratio mechanical stretching leads to deterioration of the fiber quality. Such recycled nylon 66 fiber is unsuitable for industrial materials such as airbags that require high quality, and is therefore not preferred.

[0034] Furthermore, the elongation is 15.0% to 35.0%, more preferably 17.0% to 30.0%. Higher elongation is preferred, but in practice, it is below 35.0% to obtain the required strength in nylon. By using this range, the toughness and breaking energy of the recycled nylon 66 fiber can be increased, maintaining excellent durability.

[0035] Although it also depends on the total fineness and the fineness of individual fibers, the preferred strength-to-elasticity product is 38. The above, preferably 40 The above describes the high strength-elongation product of recycled nylon 66 fiber, which suppresses fuzz and thread breakage, resulting in extremely high-quality material even at high strength. Furthermore, strength (cN / dtex) and elongation (%) refer to values ​​measured under constant-rate elongation conditions as shown in JIS L1013 (1999) 8.5.1 standard tests. The strength-elongation product is calculated by multiplying strength by... The value calculated from (elongation).

[0036] The regenerated nylon 66 fiber of the present invention preferably has a hair count of 0 to 3 fibers per 10,000 meters or less, particularly preferably 0 to 2 fibers per 10,000 meters, and even more preferably 0 to 1 fibers per 10,000 meters. This low hair count allows it to be used in applications requiring excellent hair quality, such as airbags. Furthermore, the hair count refers to the total number of hairs measured while unwinding at a speed of 150 m / min over a filament length of 100,000 meters or more, converted to the number of hairs per 10,000 meters.

[0037] The UVA value (absorbance) of the recycled nylon 66 fiber at a wavelength of 290 nm at a solution concentration of 5 mg / mL according to the present invention is preferably 0.30 or less. More preferably, it is 0.27 or less, and even more preferably, it is 0.24 or less. It is known that nylon exhibits carbonyl absorption near 290 nm when it deteriorates, and the degree of polymer deterioration can be quantitatively evaluated by measuring this absorption. If the UVA value at a wavelength of 290 nm exceeds 0.30, polymer deterioration occurs, and therefore the fiber with the high tensile strength described above cannot be obtained.

[0038] The following describes a method for manufacturing recycled polyhexamethylene adipamide resin granules (hereinafter referred to as nylon 66 granules) used in the embodiments of the present invention.

[0039] The nylon 66 process waste used in the manufacture of the nylon 66 granules in the embodiments of the present invention is generated in the fiber manufacturing process and the airbag base fabric manufacturing process, wherein there is waste generated from the spinneret installation to the drum packaging. This includes fiber manufacturing process waste such as fiber waste generated during the collection of fiber products (pushing waste), fiber waste generated due to thread breakage during spinning and stretching processes (broken thread waste), and waste that is rejected in the sorting of materials obtained as the final form of fiber products such as coiled packaging (product waste). It also includes edge waste generated during the weaving of airbag base fabric (airbag base fabric edge waste), waste generated during the scouring of airbag base fabric (airbag scouring base fabric waste), waste that is rejected in the sorting of materials obtained as the final form of airbag base fabric (airbag defective product waste), and waste generated during the cutting / sewing of airbags from airbag base fabric (airbag cutting and sewing waste). Any process waste is suitable. Furthermore, it is not limited to process waste; airbags obtained from the dismantling / separation of scrap vehicles (scrap vehicle recycled airbags) can also be used.

[0040] The manufacturing process of nylon 66 granules in the embodiments of the present invention preferably consists of the following steps: melting / filtering / discharging waste material, water cooling / cutting of discharged resin, and impregnation of granules with hot water. Furthermore, before melting the waste material, cutting the waste material, impregnating the waste material with hot water, and crushing the waste material can also be appropriately performed. Further, the impregnation of granules with hot water can be performed after water cooling / cutting of discharged resin. Each step will be described below.

[0041] In embodiments of the present invention, the moisture content of the nylon 66 process waste used in the manufacture of nylon 66 granules is preferably below 30,000 ppm. Through repeated and in-depth research, the inventors discovered that when granules formed from nylon 66 process waste with a moisture content of below 30,000 ppm are used for yarn production, raw yarn with the UVA value specified in the present invention is obtained, resulting in recycled nylon 66 fibers with excellent tensile and elongation properties.

[0042] In addition, as a method to adjust the moisture content of the waste material from the Nylon 66 process to the above-mentioned range, there are methods such as using a vacuum drying oven set to 100°C, but it is not limited to the method described herein.

[0043] The prepared waste material is then fed into the melting / filtration / discharge process. Melting methods include pressure melting and extrusion; any melting method can produce Nylon 66 flakes. Furthermore, the extruder can be either a single-shaft or a twin-shaft type.

[0044] Regarding the atmosphere in the molten zone, the oxygen partial pressure is preferably in the range of 1 to 1000 Pa, more preferably in the range of 1 to 500 Pa. Nylon 66 is prone to oxidative degradation and gelation due to oxidative degradation compared to other polymers, making it a polymer with high regeneration difficulty. Therefore, the inventors conducted repeated and in-depth research and discovered that by adjusting the oxygen partial pressure of the molten zone atmosphere to the above-mentioned range, the contact between the polymer and oxygen can be suppressed as much as possible, thereby suppressing oxidative degradation during melting. Furthermore, to adjust the oxygen partial pressure of the molten zone atmosphere to the above-mentioned range, it is preferable to replace (purge) with inactive gases such as helium, argon, or nitrogen, or to perform vacuuming.

[0045] The melting temperature of the fiber waste is 240–360°C. If the melting temperature is above 240°C, there will be no unmelted material, and there will be no problem of increased filtration pressure in the melting system, thus enabling the production of stable nylon 66 granules. If the melting temperature is below 360°C, preferably below 340°C, the thermal degradation of the nylon 66 granules can be suppressed.

[0046] It is extremely important to filter the fiber waste during the melting process. By filtering along with the melting, foreign matter can be removed from the nylon 66 granules. As a result, the pressure rise in the spinning assembly during the manufacture of nylon 66 fibers is suppressed, thus reducing spinning problems such as assembly leakage and abnormal discharge, and enabling the manufacture of nylon 66 fibers with good operability.

[0047] Regarding the filter, a filter with a filtration accuracy of 5–50 μm is preferred. If the filtration accuracy is 5 μm or higher, there will be no pressure rise in the melting system due to filter clogging, allowing for stable melting of fiber waste. If the filtration accuracy is below 50 μm, foreign matter can be removed from the nylon 66 granules. Regarding the filter, as long as filtration is performed normally, metal mesh, metal nonwoven fabric, and metal short fiber filters can all be used.

[0048] The melting / filtration time is preferably less than 5 minutes / kg. If it is less than 5 minutes / kg, the thermal process during melting / filtration can suppress the thermal degradation of nylon 66 granules and the yellowing of the resulting nylon 66 fibers.

[0049] For granulation, the melted / filtered nylon 66 resin is discharged from the die. When discharging from the die, it is preferable to discharge the granules in a manner with a diameter of 1 to 3 mm.

[0050] The nylon 66 resin discharged from the die is then used for a water cooling / cutting process. The water cooling of the nylon 66 resin should be sufficient to allow for easy cutting. Cutting of the nylon 66 resin can be performed using known methods, but a length of 1–4 mm is preferred.

[0051] Figure 1 This is a schematic diagram of a direct spinning stretching apparatus preferably used in this invention.

[0052] The following is based on Figure 1 The manufacturing method of the recycled nylon 66 fiber of the present invention will be described using an example.

[0053] First, nylon raw material granules are prepared to become the raw material for the recycled nylon 66 fiber of the present invention. The polymerization method for the nylon can be a known polymerization method.

[0054] The relative viscosity (hereinafter referred to as viscosity) of the raw material granules for the recycled nylon 66 fiber of the present invention is preferably 2.8 to 3.9, more preferably 3.0 to 3.9. When metering and mixing the recycled nylon 66 granules with virgin nylon 66 granules, the weighted average of the viscosity / ratio of each granule is acceptable as long as it falls within the above range. If the viscosity of the granules exceeds 3.9, when the total fineness is set within the range specified in the present invention, micro-deterioration and hairiness occur due to thickening, thermal degradation, and gelation caused by long-term polymer retention, resulting in the formation of small foreign matter. When the viscosity of the granules is less than 2.8, it is difficult to obtain recycled nylon 66 fibers with the strength specified in the present invention. Furthermore, the relative viscosity of sulfuric acid refers to the value measured at 25°C using an Ostwald viscometer after dissolving the sample in 98% sulfuric acid.

[0055] The recycled nylon 66 fiber of the present invention is preferably manufactured by metering recycled nylon 66 granules, or metering and mixing recycled nylon 66 granules and virgin nylon 66 granules, drying them to adjust to a specified moisture content, and then manufacturing them through a manufacturing process consisting of conventional melt spinning, cooling, oiling, and stretching. The manufacturing apparatus used in embodiments of the present invention has a mixing device, either within or separate from the melt spinning apparatus, for metering and mixing recycled nylon 66 granules and virgin nylon 66 granules. The melt spinning apparatus used in embodiments of the present invention can be an extrusion spinning machine or a pressure melting spinning machine. When a colorant is added, granules mixed with a masterbatch containing a high concentration of colorant can be fed into the spinning machine, and each granule can be metered and fed in directly above the spinning machine. Alternatively, the colorant can be added directly to the spinning machine in powder or liquid form.

[0056] Next, the metered nylon granules are fed into an extrusion spinning machine and fed into the spinneret via a metering pump for melt spinning. At this time, to suppress polymer thickening, thermal degradation, and gelation, the pressure in the extruder supply section is preferably under vacuum (0.0 kPa). Furthermore, the spinning temperature is set to a value 50°C higher than the polymer's melting point. The nylon discharged from the spinneret 1 preferably passes through a heating cylinder 2 located 5 to 300 cm directly below the spinneret. The temperature inside this heating cylinder is preferably -30 to +30°C, more preferably -15 to +15°C, which is the melting point of the polymer nylon. By passing through a high-temperature atmosphere surrounded by the heating cylinder and slowly cooling the spun filaments without direct cooling, the orientation of the melt-spun nylon molecules is moderated, improving the uniformity of molecular orientation between individual fibers. Therefore, it is possible to achieve high strength in recycled nylon 66 fibers. On the other hand, if the undrawn yarn is cooled directly without passing through a high-temperature atmosphere, the orientation of the undrawn yarn increases, and the orientation deviation between individual fibers becomes larger. If such undrawn yarn is hot-drawn, it is possible that high-strength recycled nylon 66 fibers cannot be obtained as a result.

[0057] The unstretched filament 5, after passing through a high-temperature atmosphere, is then cooled and solidified by spraying air at 10–80°C, preferably 10–50°C, through a cross-flow cooling device 3. When the cooling air exceeds 80°C, the swaying of the individual fibers during spinning increases, leading to collisions between the individual fibers and causing a deterioration in the spinning properties.

[0058] The resulting cooling filament can then be oiled using a known oiling device 4, pulled by a traction roller 6 (1FR), stretched, and then wound. A known oil can be used, but to suppress monofilament entanglement on the traction roller 6, its application amount is preferably 0.3 to 1.5% by weight, more preferably 0.5 to 1.0% by weight.

[0059] Furthermore, the spinning speed, defined by the rotational speed of the traction roller 6, is preferably 500 to 1000 m / min, more preferably 600 to 800 m / min. If the spinning speed is 500 m / min or higher, the final production speed becomes sufficient, production efficiency is good, and recycled nylon 66 fibers can be manufactured cheaply. If it is 1000 m / min or lower, frequent yarn breakage and fuzzing can be prevented, which is preferable. Furthermore, the stretching speed, expressed by the maximum speed of the stretching roller, is preferably 2800 m / min or higher, more preferably 3000 m / min or higher.

[0060] The spun yarn obtained by the above method can be stretched, relaxed, heat-treated, and wound using known methods. Here, we will specifically illustrate the case of two-stage stretching. The spun yarn, which is stretched by the traction roller 6, is wound into the winding machine 11 in the following order: feed roller 7 (2FR), first stretch roller 8 (1DR), second stretch roller 9 (2DR), and relaxation roller 10 (RR).

[0061] Pre-stretching is performed between 1FR and 2FR, the first stage of stretching is performed between 2FR and 1DR, and the second stage of stretching is performed between 1DR and 2DR. The temperature of 2FR is set to 30–50°C, and the temperature of 1DR is set to 100–225°C. Pre-stretching and the first stage of stretching are preferably performed before or after the glass transition temperature. The remaining stretching and heat setting are typically performed at a high temperature of 180–240°C, more preferably 200–220°C.

[0062] Regarding the overall draw ratio (hereinafter also simply referred to as draw ratio), that is, the ratio between the traction roller 6 and the second draw roller 9, a high draw ratio is preferred in order to obtain high-strength recycled nylon 66 fibers. If it is within the fineness range described in this invention, a draw ratio of 3.8 to 5.0 is sufficient. Furthermore, the winding speed is generally preferred to be 2000 to 5000 m / min, more preferably 2500 to 4500 m / min. Moreover, it is preferable to wind the yarn into a package using a winding device under a winding tension of 20 to 250 gf.

[0063] The high-strength and high-quality recycled nylon 66 fiber described in this invention can be manufactured using the methods described above.

[0064] Example

[0065] The present invention will now be described in detail through examples. The definitions and measurement methods of the various characteristics in the present invention are as follows.

[0066] (1) Relative viscosity of sulfuric acid (ηr): Using polymer granules or fibers as samples, 0.25 g of the sample was dissolved in 25 ml of 98% sulfuric acid and measured using an Ostwald viscometer at 25 °C. The viscosity was calculated using the following formula. The measured value was obtained by averaging five samples.

[0067] ηr = Number of seconds for the sample solution to flow down / Number of seconds for sulfuric acid to flow down only.

[0068] (2) UVA value (absorbance): Using polymer granules or fibers as samples, 1g or 0.1g of the sample was dissolved in 20ml of formic acid. The spectrum was measured using a HITACHI self-recording spectrophotometer U-3900H at a temperature of 25℃ and a wavelength range of 250~340nm. The absorbance at 290nm was read from the obtained spectrum.

[0069] (3) Total fineness: determined by JIS L1090 ​​(1999).

[0070] (4) Number of single fibers: calculated by the method of JIS L1013(1999) 8.4.

[0071] (5) Single fiber fineness: Calculated by dividing the total fineness by the number of single fibers.

[0072] (6) Strength / Elongation: Determined under constant elongation conditions as shown in JIS L1013(1999) 8.5.1 standard test. The specimens were tested using a TENSILON UCT-100 (manufactured by Original Tech Co.), with a clamp spacing of 25 cm and a tensile speed of 30 cm / min. Strength was determined from the maximum strength in the SS curve, and elongation was determined from the elongation at the point showing the maximum strength in the SS curve. Strength was obtained by dividing the strength by the total fineness.

[0073] (7) Number of fibers: The obtained fiber roll was unwound at a speed of 150 m / min. A laser fiber detector "Flight V" manufactured by Huberline Co., Ltd. was installed 2 m away from the unwound filaments, and the total number of fibers detected was evaluated. The evaluation was conducted for more than 100,000 meters and expressed as the number of fibers per 10,000 meters.

[0074] (Example 1)

[0075] <Manufacturing of Virgin Nylon 66 Granules>

[0076] A 5% by weight aqueous solution of copper acetate as an antioxidant was added to nylon 66 granules obtained by liquid-phase polymerization, resulting in an adsorption of 68 ppm of copper relative to the polymer weight. Next, a 50% by weight aqueous solution of potassium iodide and a 20% by weight aqueous solution of potassium bromide were added at a rate of 0.1 parts by weight of potassium per 100 parts by weight of polymer granules, respectively. Solid-phase polymerization was then carried out using a batch solid-phase polymerization apparatus to obtain nylon 66 granules with a relative viscosity of 3.75 for sulfuric acid.

[0077] <Manufacturing of recycled nylon 66 pellets>

[0078] Waste material from defective airbags was melted at 340°C using a pressure melter with an oxygen partial pressure of 50 Pa achieved through N2 purging and vacuuming. The molten polymer was then fed into a single-shaft extruder. The extruder was set to melt at 290°C while maintaining a front-end pressure of 8 MPa, and the material was filtered using a nonwoven fabric filter with a filtration precision of 37 μm. The discharge rate was adjusted to a total melt-filtration time of 5 minutes / kg. The filtered molten polymer was discharged from the die, water-cooled, and cut to obtain recycled nylon 66 pellets with a diameter of 1.2 mm and a length of 2.0 mm.

[0079] <Manufacturing of Recycled Nylon 66 Fiber>

[0080] The obtained virgin nylon 66 pellets and recycled nylon 66 pellets were metered / mixed at the ratios listed in Table 1 and fed into an extruder with a diameter of 110 mm, where they were melted under vacuum at a melt temperature of 300°C. The molten polymer was metered and pumped into the spinning assembly to obtain multifilaments with a total fineness of 470 dtex. The molten polymer was then filtered through a metal nonwoven fabric filter with a pore size of 15 μm within the spinning assembly and spun through a die with 72 circular orifices. A 15 cm long heating cylinder was installed 3 cm below the die surface, and the cylinder was heated to a temperature of 250°C. The internal atmosphere temperature is the air temperature at the center of the heating cylinder, 1 cm from the inner wall. A unidirectional flow chimney was installed directly below the heating cylinder, spraying 20°C cold air at a speed of 35 m / min onto the filaments for cooling and solidification. An oiling agent was then applied to the filaments.

[0081] Unstretched filaments treated with an oiling agent were wound onto a 1FR roller rotating at a surface speed of 818 m / min and then stretched at a comprehensive stretch ratio of 4.5. The traction filaments were then continuously stretched by 5% between the traction roller and the 2FR roller without being wound, followed by a first stage of stretching at a speed ratio of 2.80, a second stage of stretching at a speed ratio of 1.46, and finally wound at a speed of 3358 m / min. The roller surfaces of 1FR and 2FR were mirror-polished, while 1DR, 2DR, and RR were pear-skin polished. Furthermore, the roller temperatures were as follows: 1FR unheated, 2FR 40°C, 1DR 150°C, 2DR 225°C, and RR 150°C. Recycled nylon 66 fibers were obtained through this melt spinning and stretching process. The weaving process was performed by injecting high-pressure air perpendicular to the moving filament within a weaving application device. Guides that restrict the movement of the filaments are set before and after the interlacing application device, and the pressure of the injected air is kept constant at 0.4 MPa.

[0082] (Example 2)

[0083] The raw material for the recycled nylon 66 pellets was changed to waste from the fiber manufacturing process, the overall stretch ratio was changed to 4.8 times, and the ratio of recycled pellets was changed to 100%. Otherwise, it was carried out in the same manner as in Example 1.

[0084] (Example 3)

[0085] The raw material for the recycled nylon 66 granules was changed to waste material from the edge of the airbag base fabric. The overall tensile ratio was changed to 4.6 times, the proportion of recycled granules was changed to 50%, and the total fineness of the recycled nylon 66 fibers was changed to 110 dtex. Otherwise, it was carried out in the same manner as in Example 1.

[0086] (Example 4)

[0087] The raw material for the recycled nylon 66 granules was waste material from the cutting and sewing of airbags. The overall stretch ratio was 5.8 times, the stretching speed was 2645 m / min, the ratio of recycled granules was 5%, and the total fineness of the recycled nylon 66 fibers was 1400 dtex. Otherwise, it was carried out in the same manner as in Example 1.

[0088] (Example 5)

[0089] The raw material for the recycled nylon 66 granules was recycled airbags from scrap vehicles. The overall stretch ratio was 5.7 times, the stretching speed was 2050 m / min, and the total fineness of the recycled nylon 66 fibers was 2100 dtex. Otherwise, it was carried out in the same manner as in Example 1.

[0090] (Example 6)

[0091] The raw material for the recycled nylon 66 pellets is the base fabric waste from the refining process. The molten atmosphere during the manufacturing of the recycled nylon 66 pellets is a vacuum. The total fineness of the recycled nylon 66 fibers is 350 dtex. Otherwise, it is carried out in the same manner as in Example 1.

[0092] (Comparative Example 1)

[0093] The ratio of raw material pellets used was changed to 100% virgin pellets, and the overall stretch ratio was changed to 4.4 times. Otherwise, it was carried out in the same manner as in Example 1.

[0094] (Comparative Example 2)

[0095] The molten atmosphere during the manufacture of recycled nylon 66 pellets was the same as in Example 1, except that it was the same as in Example 1.

[0096] (Comparative Example 3)

[0097] The raw material moisture content of the recycled nylon 66 pellets was 49,000 ppm, and the ratio of recycled pellets was 100%. Otherwise, it was carried out in the same manner as in Example 1.

[0098] (Comparative Example 4)

[0099] The raw material moisture content of the recycled nylon 66 pellets was 150,000 ppm, and the ratio of recycled pellets was 100%. Otherwise, it was carried out in the same manner as in Example 1.

[0100]

[0101] The physical properties of the virgin nylon 66 fibers obtained in Comparative Example 1, and the recycled nylon 66 fibers obtained in Examples 1-6 and Comparative Examples 2-4 were evaluated, and the results are shown in Table 1.

[0102] As shown in Table 1, the recycled nylon 66 fiber of the present invention has the same tensile strength as the virgin nylon 66 fiber, while also having good hair quality.

[0103] In Examples 1 to 5, the recycled nylon 66 fibers of the present invention were manufactured by making various changes to the type of recycled raw materials, the proportion of recycled nylon 66, and the total fineness of the fibers, and all of them obtained the same degree of filament characteristics as virgin nylon 66 fibers.

[0104] Furthermore, as in Example 6, when the pre-melting atmosphere during the manufacture of recycled nylon 66 pellets was changed to a vacuum, the viscosity of the pellets increased due to the removal of moisture contained in the recycled raw materials, but the UVA value did not deteriorate. As a recycled fiber, it still obtained the same filament characteristics as the virgin fiber. On the other hand, as in Comparative Example 2, when the pre-melting atmosphere during the manufacture of recycled nylon 66 pellets was changed to atmospheric air, it was observed that the UVA value deteriorated, and the tensile strength and hairiness of the filament worsened compared to the virgin fiber.

[0105] Furthermore, as in Comparative Examples 3 and 4, when the moisture content of the process waste that becomes the raw material for recycled nylon 66 pellets exceeds 30,000 ppm, it can be seen that the UVA value of the pellets deteriorates. As a result, the tensile strength of the virgin filament deteriorates compared to that of the virgin fiber.

[0106] The results above suggest that reducing the oxygen partial pressure of the pre-melting atmosphere during the manufacturing of recycled nylon 66 pellets and controlling the moisture content of the process waste that will become the raw material for recycled nylon 66 pellets within a specified range are important for manufacturing high-strength recycled nylon 66 fibers with good hair quality suitable for industrial applications.

[0107] Industry availability

[0108] The recycled nylon 66 fiber of this invention is suitable for the sustainable materialization of industrial materials such as airbags and tire cords due to its high strength and good hair quality.

[0109] Explanation of symbols

[0110] 1: Spinneret

[0111] 2: Heating cylinder

[0112] 3: Cross-flow cooling device

[0113] 4: Refueling device

[0114] 5: Silk strips

[0115] 6: Traction Roller (1FR)

[0116] 7: Yarn feed roller (2FR)

[0117] 8: First stretching roller (1DR)

[0118] 9: Second stretching roller (2DR)

[0119] 10: Relaxation Roller (RR)

[0120] 11: Winding machine.

Claims

1. A type of recycled nylon 66 fiber, characterized in that, It contains more than 5% by weight of recycled nylon 66, with a total fineness of 110 to 2100 dtex, a strength of 7.6 to 10.0 cN / dtex, and an elongation of 15.0 to 35.0%.

2. The recycled nylon 66 fiber according to claim 1, characterized in that, The UVA value (absorbance) at a wavelength of 290 nm at a solution concentration of 5 mg / mL is below 0.

30.

3. The recycled nylon 66 fiber according to claim 1 or 2, characterized in that, The number of feathers is 0 to 3 per 10,000 meters.

4. The recycled nylon 66 fiber according to any one of claims 1 to 3, wherein the recycled nylon 66 fiber is manufactured from granules made from one or more of the following raw materials: waste from fiber manufacturing process, waste from the edge of airbag base fabric, waste from base fabric during scouring, waste from defective airbags, waste from airbag cutting and sewing, and airbags recycled from scrap vehicles.

5. A fabric for airbags, characterized in that, The recycled nylon 66 fiber as described in claim 1 or 2 was used.

6. A tire cord, characterized in that, The recycled nylon 66 fiber as described in claim 1 or 2 was used.

7. A racket string, characterized in that, The recycled nylon 66 fiber as described in claim 1 or 2 was used.

8. A multi-wedge belt, characterized in that, The recycled nylon 66 fiber as described in claim 1 or 2 was used.

9. A fabric for bags and luggage, characterized in that, The recycled nylon 66 fiber as described in claim 1 or 2 was used.

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