Material-recycled nylon 66 fiber

Abstract

This recycled nylon 66 fiber is characterized by including 5 wt% or more of recycled nylon 66 and having an overall fineness of 110-2100 dtex, a strength of 7.6-10.0 cN / dtex, and an elongation of 15.0-35.0%.　Provided is a material-recycled nylon 66 fiber having high strength and a good fluff quality.

Description

Material: Recycled nylon 66 fiber

[0001] The present invention relates to nylon 66 fibers made from recycled polyhexamethylene adipamide resin and a method for producing the same.

[0002] Nylon 6 and nylon 66 multifilaments have higher strength and elongation and superior fluff quality compared to general-purpose multifilaments such as polyester and polypropylene, and are therefore used in a wide range of industrial applications, such as airbags, tire cords, strings for sports rackets, ropes, fishing nets, and bag belts.

[0003] Furthermore, with the recent rise in environmental awareness, the value of environmentally friendly materials, for example, products made from recycled raw materials, is increasing, and there is a demand for the development of fibers made from recycled raw materials.

[0004] Nylon 6 and polyester can be recycled relatively easily, and methods for producing recycled fibers having properties almost equivalent to those of virgin fibers have been disclosed, as in Patent Documents 1 and 2 listed below.

[0005] Patent Document 3 discloses a method for producing recycled nylon fiber by crushing and washing nylon waste materials, including nylon 66 all-gloss yarn, nylon 66 semi-gloss yarn, nylon 66 matte yarn, nylon 66 ultra-high strength yarn, nylon 66 high strength yarn, nylon 66 fine duny high strength yarn, nylon 66 fishing net waste wire, and nylon 66 waste cloth, to reduce the oil content to 0.22% by weight, followed by dehydration and melt granulation to produce material recycled nylon resin chips, and melt spinning the material recycled nylon chips. However, Patent Document 3 states that the draw ratio in the drawing step included in the fiber production process is set to 1.2 to 1.5 times, and that if the draw ratio exceeds 1.5 times, the yarn becomes prone to breakage due to excessive drawing, making it clear that the strength level required for industrial fibers cannot be achieved.

[0006] International Publication No. 2022 / 196407 Japanese Patent Application Laid-Open No. 2003-13328 Japanese Patent No. 6629943

[0007] However, nylon 66 is more susceptible to thermal and oxidative degradation and gelation than other polymers, making it difficult to recycle.

[0008] The object of the present invention is to solve the above-mentioned problems by suppressing polymer degradation due to heat, oxidative degradation, etc., and to obtain material recycled nylon 66 fiber having strength, elongation, and fluff quality equivalent to those of 100% virgin nylon 66 fiber.

[0009] The present invention was developed through extensive research to solve the above-mentioned problems and has the following features: (1) A recycled nylon 66 fiber containing 5% by weight or more of recycled nylon 66 resin and having 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 (1) above, characterized in that the UVA value at a wavelength of 290 nm in a solution concentration of 5 mg / mL is 0.30 or less. (3) The recycled nylon 66 fiber according to (1) or (2) above, characterized in that the fuzz count is 0 to 3 pieces / 10,000 m. (4) The recycled nylon 66 fiber according to any one of (1) to (3) above, which is produced from repellent chips using any one or more of waste from the fiber manufacturing process, waste airbag fabric edge scraps, waste fabric scraps from scouring processing, waste airbag rejects, waste airbag cutting and sewing of airbags, and airbags collected from scrapped vehicles. (5) A fabric for an airbag, characterized by using the recycled nylon 66 fiber described in (1) or (2). (6) A tire cord, characterized by using the recycled nylon 66 fiber described in (1) or (2). (7) A racket string, characterized by using the recycled nylon 66 fiber described in (1) or (2). (8) A V-ribbed belt, characterized by using the recycled nylon 66 fiber described in (1) or (2). (9) A fabric for a bag, characterized by using the recycled nylon 66 fiber described in (1) or (2).

[0010] The present invention makes it possible to obtain material recycled nylon 66 fibers having the same strength and elongation as 100% virgin nylon 66 fibers and good fluff quality.

[0011] 1 is a schematic diagram of the material recycled nylon 66 fiber manufacturing process of the present invention.

[0012] The present invention will be described in detail below.

[0013] The material recycled nylon 6,6 fiber according to an embodiment of the present invention is preferably nylon 6,6 blended with 5% by weight or more of the fiber containing recycled polyhexamethylene adipamide resin. That is, the recycled nylon 6,6 fiber of the present invention contains 5% by weight or more of recycled polyhexamethylene adipamide resin. In view of the growing awareness of global environmental conservation in recent years, the higher the blending amount, the better, and nylon 6,6 fiber blended with 20% by weight to 100% by weight of recycled polyhexamethylene adipamide resin is preferred.

[0014] The polyhexamethylene adipamide resin may contain, for example, 10 mol% or less of other copolymerization components within the range that does not impair the effects of the present invention, but it is preferable to contain a large amount of hexamethylene adipamide units, because this increases the regularity of the molecular chains of the resulting fiber, making it easier for oriented crystallization to occur during the spinning process, resulting in a fiber with excellent mechanical properties. The hexamethylene adipamide unit content is more preferably 95 mol% or more, and even more preferably 98 mol% or more.

[0015] The recycled nylon 6,6 fiber of the present invention may contain, as necessary, components other than nylon, such as an end-capping agent such as monocarboxylic acid, a delustering agent such as titanium oxide, a polymerization catalyst or heat-resistant agent such as a phosphorus compound, an antioxidant or heat stabilizer such as a copper compound or an alkali metal or alkaline earth metal halide, but the nylon component is preferably 95% by weight or more, more preferably 97% by weight or more. If the nylon component is less than 95% by weight, the heat resistance of the nylon will decrease, which is not preferred.

[0016] The recycled nylon 66 fiber of the present invention has a total fineness of 110 to 2100 dtex. A more preferred range is 350 to 2100 dtex. A fineness of less than 110 dtex is too thin to withstand the high mechanical drawing ratio required to achieve high strength, increasing the likelihood of fuzz generation. A fineness exceeding 2100 dtex is undesirable because it reduces cooling efficiency and mechanical properties. Furthermore, the single fiber fineness is preferably 2 to 35 dtex. A single fiber fineness of 2 to 35 dtex allows for stable production of high-strength recycled 66 fiber while maintaining quality. There are no particular restrictions on the number of single fibers; the important factor is the single fiber fineness.

[0017] The recycled nylon 66 fiber of the present invention has a strength of 7.6 to 10.0 cN / dtex. It is preferably 8.0 to 9.7 cN / dtex, and more preferably 8.5 to 9.7 cN / dtex. A strength within this range results in a nylon fiber suitable for industrial materials such as airbags and durable clothing fabrics. A strength of less than 7.6 cN / dtex is insufficient to improve the durability of fibers for industrial materials such as airbags. When attempting to obtain nylon fibers with a strength exceeding 10.0 cN / dtex, mechanical drawing is required at a high ratio, resulting in poor fluff quality. Such recycled nylon 66 fibers are unsuitable for industrial materials such as airbags, which require high quality, and are therefore undesirable.

[0018] The elongation is preferably 15.0% to 35.0%, and more preferably 17.0% to 30.0%. Although a higher elongation is preferable, a practical elongation of 35.0% or less is required to obtain a desired strength with nylon. By keeping the elongation within this range, the toughness and breaking load of the recycled nylon 66 fiber can be increased, and excellent durability can be maintained.

[0019] Although it depends on the total fineness and single fiber fineness, the strength-strain product is preferably 38 cN / dtex × √% or more, and more preferably 40 cN / dtex × √% or more. A high strength-strain product suppresses the generation of fluff, yarn breakage, etc., and results in a high-strength, extremely high-quality recycled nylon 66 fiber. Note that the strength (cN / dtex) and elongation (%) refer to values ​​measured under the constant-rate elongation conditions specified in JIS L1013 (1999) 8.5.1 standard time test, and the strength-strain product is a value calculated by multiplying strength by √(elongation).

[0020] The recycled nylon 6,6 fiber of the present invention preferably has a fluff count of 0 to 3 fluffs / 10,000 m or less, particularly 0 to 2 fluffs / 10,000 m, and even more preferably 0 to 1 fluff / 10,000 m. A low fluff count enables the fiber to be used in applications requiring excellent fluff quality, such as airbags. The fluff count is calculated by measuring the total fluff count over a filament length of 100,000 m or more while rewinding at a speed of 150 m / min, and converting it to the number of fluffs per 10,000 m.

[0021] The UVA value (absorbance) at a wavelength of 290 nm of the recycled nylon 6,6 fiber of the present invention at a solution concentration of 5 mg / mL is preferably 0.30 or less, more preferably 0.27 or less, and even more preferably 0.24 or less. It is known that as nylon degradation progresses, it exhibits carbonyl group absorption around 290 nm, and measuring this absorption allows the degree of polymer degradation to be quantitatively evaluated. If the UVA value at a wavelength of 290 nm exceeds 0.30, polymer degradation has progressed, making it impossible to obtain a fiber with the high strength and elongation described above.

[0022] Hereinafter, a method for producing recycled polyhexamethylene adipamide resin chips (hereinafter referred to as nylon 66 chips) used in the recycled nylon 66 fiber according to an embodiment of the present invention will be described.

[0023] The nylon 66 process scrap used in the production of nylon 66 chips in an embodiment of the present invention is generated in the fiber manufacturing process and the airbag base fabric manufacturing process. This includes fiber scraps (washed-in scraps) generated between the time the spinneret is attached and the time it is collected as a fiber product such as a drum package, fiber scraps (broken thread scraps) generated due to thread breakage problems during the spinning or drawing process, and scraps (product scraps) obtained as the final form of a fiber product such as a drum package that have failed product selection. Also, scraps (airbag base fabric ear end scraps) generated when weaving the airbag base fabric, scraps generated during the scouring process of the airbag base fabric (airbag scouring base fabric scraps), scraps (airbag rejected product scraps) obtained as the final form of the airbag base fabric that have failed product selection, and scraps (airbag cutting and sewing scraps) generated when cutting and sewing airbags from the airbag base fabric. Any of these process scraps can be suitably used. In addition to process scraps, airbags obtained by dismantling and sorting from scrapped cars (scrapped car collected airbags) can also be used.

[0024] The nylon 66 chip manufacturing process in an embodiment of the present invention preferably comprises the steps of melting, filtering, and discharging scraps, water-cooling and cutting the extruded resin, and immersing the chips in hot water. Furthermore, before melting the scraps, the scraps may be appropriately cut, immersed in hot water, and crushed. Furthermore, after water-cooling and cutting the extruded resin, the chips may be immersed in hot water. Each step is described below.

[0025] The moisture content of the nylon 66 process scrap used in the production of nylon 66 chips in an embodiment of the present invention is preferably 30,000 ppm or less. As a result of extensive research, the inventors have found that when nylon 66 process scrap with a moisture content of 30,000 ppm or less is repellentized and used for spinning, a raw yarn having the UVA value specified in the present invention can be obtained, and a material recycled nylon 66 fiber having excellent strength and elongation can be obtained.

[0026] The moisture content of nylon 66 process scrap can be adjusted to the above range by, for example, subjecting it to a vacuum drying oven set at 100°C, but the method is not limited to the methods described herein.

[0027] The prepared scraps are subjected to the melting, filtering, and extrusion processes. The melting method can be a pressure melter or an extruder, and nylon 66 chips can be produced using either method. The extruder can be either a single-screw or twin-screw type.

[0028] The oxygen partial pressure of the melting zone atmosphere is preferably 1 to 1,000 Pa, more preferably 1 to 500 Pa. Nylon 66 is more susceptible to oxidative degradation and the accompanying gelation than other polymers, making it a polymer that is difficult to recycle. Therefore, the inventors conducted extensive research and found that oxidative degradation during melting can be suppressed by adjusting the oxygen partial pressure of the melting zone atmosphere to the above range and minimizing contact between the polymer and oxygen as much as possible. Adjusting the oxygen partial pressure of the melting zone atmosphere to the above range is preferably achieved by replacing (purging) the atmosphere with an inert gas such as helium, argon, or nitrogen, or by evacuating the atmosphere.

[0029] The melting temperature of the fiber waste is 240 to 360°C. If the melting temperature is 240°C or higher, there is no occurrence of unmelted material, and stable production of nylon 66 chips is possible without problems such as an increase in filtration pressure in the melting system. If the melting temperature is 360°C or lower, preferably 340°C or lower, thermal degradation of the nylon 66 chips can be suppressed.

[0030] It is extremely important to perform filtration simultaneously when melting the fiber waste. By performing filtration simultaneously with melting, foreign matter can be removed from the nylon 66 chips, and as a result, an increase in the internal pressure of the spin pack during the production of nylon 66 fiber is suppressed, thereby reducing spinning problems such as pack leakage and discharge abnormalities, and enabling the production of nylon 66 fiber with good operability.

[0031] It is preferable to use a filter with a filtration accuracy of 5 to 50 μm. A filtration accuracy of 5 μm or more allows for stable melting of fiber waste without increasing pressure in the melting system due to filter clogging. A filtration accuracy of 50 μm or less allows for removal of foreign matter from nylon 66 chips. Any filter can be used, such as a wire mesh type, metal nonwoven fabric type, or metal short fiber type, as long as it can perform filtration normally.

[0032] The melting and filtration time is preferably 5 minutes / kg or less, which can suppress thermal degradation of the nylon 66 chips due to the thermal history experienced during melting and filtration, and can suppress yellowing of the resulting nylon 66 fiber.

[0033] The melted and filtered nylon 66 resin is extruded from a die to form pellets, preferably in a pellet diameter of 1 to 3 mm.

[0034] The nylon 66 resin discharged from the die is subjected to a water-cooling and cutting process. The nylon 66 resin may be water-cooled to a degree that allows the nylon 66 resin to be easily cut. The nylon 66 resin may be cut by a known method, but it is preferable to cut it into lengths of 1 to 4 mm.

[0035] FIG. 1 is a schematic diagram of a direct spinning and drawing apparatus preferably used in the present invention.

[0036] The method for producing the material recycled nylon 66 fiber of the present invention will be described below using FIG. 1 as an example.

[0037] First, raw nylon chips are prepared as the raw material for the material recycled nylon 66 fiber of the present invention. As the nylon polymerization method, a known polymerization method can be used.

[0038] The sulfuric acid relative viscosity (hereinafter referred to as viscosity) of the raw material chips 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 material recycled nylon 66 chips and virgin nylon 66 chips are weighed and mixed, the weighted average value based on the viscosity and ratio of each chip should fall within the above range. If the viscosity of the chips exceeds 3.9, when the total fineness is within the range specified in the present invention, the polymer will thicken due to long-term retention, thermal degradation, gelation, etc., resulting in the generation of minute foreign matter and a deterioration in fluff quality. If the viscosity of the chips is less than 2.8, it will be difficult to obtain recycled nylon 66 fiber with the strength specified in the present invention. The sulfuric acid relative viscosity refers to the value measured at 25°C by dissolving a sample in 98% sulfuric acid and using an Ostwald viscometer.

[0039] The recycled nylon 66 fiber of the present invention is preferably produced by a manufacturing process consisting of weighing material recycled nylon 66 chips or weighing and mixing material recycled nylon 66 chips with virgin nylon 66 chips, drying to adjust to a predetermined moisture content, followed by so-called conventional melt spinning, cooling, oiling, and drawing. The manufacturing apparatus used in embodiments of the present invention includes a mixer, either within the melt spinning apparatus or separately from the melt spinning apparatus, capable of weighing and mixing the material recycled nylon 66 chips and virgin nylon 66 chips. The melt spinning apparatus used in embodiments of the present invention can be either an extruder-type spinning machine or a pressure melter-type spinning machine. When a colorant is added, master chips containing a high concentration of colorant may be mixed with base chips and the resulting mixture may be added to the spinning machine, or each chip may be weighed and added directly above the spinning machine. Alternatively, the colorant may be added directly to the spinning machine in powder or liquid form.

[0040] Next, the measured nylon chips are fed to an extruder-type spinning machine and placed in a spinneret by a metering pump for melt spinning. In this process, the pressure in the extruder feed section is preferably a vacuum (0.0 kPa) to suppress polymer thickening, thermal degradation, and gelation. The spinning temperature is set to a value 50°C higher than the melting point of the polymer. The nylon discharged from spinneret 1 is preferably passed through a heating barrel 2 that surrounds the area 5 to 300 cm from directly below the spinneret. The temperature inside this heating barrel is preferably −30 to +30°C relative to the melting point of the nylon polymer, and more preferably −15 to +15°C relative to the melting point. By slowly cooling the spun yarn through a high-temperature atmosphere surrounded by the heating barrel rather than immediately cooling it, the orientation of the melt-spun nylon molecules is relaxed, improving the uniformity of molecular orientation between single fibers, thereby enabling the high strength of material recycled nylon 66 fibers. On the other hand, if the undrawn yarn is cooled immediately without passing through a high-temperature atmosphere, the orientation of the undrawn yarn increases and the variation in the degree of orientation among the individual fibers increases. If such an undrawn yarn is hot-drawn, it may not be possible to obtain a high-strength recycled nylon 66 fiber.

[0041] The undrawn yarn 5 that has passed through the high-temperature atmosphere is then cooled and solidified by blowing air at a temperature of 10 to 80°C, preferably 10 to 50°C, onto it in a cross-flow cooler 3. If the cooling air temperature exceeds 80°C, the vibration of the single fibers during spinning increases, causing collisions between the single fibers and the like, which deteriorates spinnability.

[0042] Thereafter, the cooled yarn obtained is oiled by a known oiling device 4, taken up by a take-up roller 6 (1FR), stretched, and then wound up. Any known oil can be used as the oil, but in order to prevent the single yarn from winding on the take-up roller 6, the amount of oil applied is preferably 0.3 to 1.5% by weight, more preferably 0.5 to 1.0% by weight.

[0043] Furthermore, the spinning speed, defined as the rotation speed of the take-up roller 6, is preferably 500 to 1,000 m / min, more preferably 600 to 800 m / min. A spinning speed of 500 m / min or higher ensures a sufficient final production speed, enabling efficient and inexpensive production of material recycled nylon 66 fiber. A spinning speed of 1,000 m / min or lower is preferable because it prevents frequent yarn breakage and fuzzing. Furthermore, the drawing speed, which is expressed as the maximum speed of the drawing roll, is preferably 2,800 m / min or higher, more preferably 3,000 m / min or higher.

[0044] The spun yarn obtained by the above-mentioned methods can be drawn, heat-treated for relaxation, and wound up using known methods. To give a specific example of two-stage drawing, the spun yarn taken up by the take-up roller 6 is wound around the yarn feed roller 7 (2FR), the first drawing roller 8 (1DR), the second drawing roller 9 (2DR), and the relaxation roller 10 (RR) in this order, where it is subjected to heat treatment and drawing, and then wound up on the winder 11.

[0045] Pre-stretching is performed between 1FR and 2FR, the first-stage stretching is performed between 2FR and 1DR, and the second-stage stretching is performed between 1DR and 2DR. The temperature of 2FR is preferably set to 30 to 50°C, the temperature of 1DR to 100 to 225°C, and the pre-stretching and first-stage stretching are preferably hot stretched at around the glass transition temperature. The remaining stretching and heat setting temperatures are preferably performed at high temperatures, typically 180 to 240°C, more preferably 200 to 220°C.

[0046] Regarding the total draw ratio (hereinafter simply referred to as the draw ratio), i.e., the ratio between the take-up roller 6 and the second draw roller 9, a high draw ratio is preferred to obtain high-strength recycled nylon 66 fibers. For the fineness range described in the present invention, drawing at 3.8 to 5.0 times is sufficient. The winding speed is preferably 2000 to 5000 m / min, more preferably 2500 to 4500 m / min. Furthermore, it is preferred that the winding tension be 20 to 250 gf, and the fibers are wound into a cheese strip by a winding device.

[0047] By the above-described method, the recycled nylon 66 fiber described in the present invention, which has high strength and good fluff quality, can be produced.

[0048] The present invention will be described in detail below with reference to examples. The definitions and measuring methods of the various properties in the present invention are as follows.

[0049] (1) Sulfuric acid relative viscosity (ηr): Using polymer chips or fibers as a sample, 0.25 g of the sample was dissolved in 25 ml of 98% sulfuric acid, and the viscosity was measured at 25°C using an Ostwald viscometer. The viscosity was calculated using the following formula. The measured value was calculated from the average value of five samples: ηr = number of seconds for the sample solution to flow down / number of seconds for sulfuric acid alone to flow down.

[0050] (2) UVA value (absorbance): Using a polymer chip or fiber as a sample, 1 g or 0.1 g of the sample was dissolved in 20 ml of special-grade formic acid, and the absorbance at 290 nm was read from the spectrum measured at a temperature of 25°C in the wavelength range of 250 to 340 nm using a Hitachi U-3900H self-recording spectrophotometer.

[0051] (3) Total fineness: Measured according to JIS L1090 ​​(1999).

[0052] (4) Number of single fibers: Calculated according to the method of JIS L1013 (1999) 8.4.

[0053] (5) Single fiber fineness: Calculated by dividing the total fineness by the number of single fibers.

[0054] (6) Tenacity, strength, and elongation: Measurements were made under the constant-speed elongation conditions specified in JIS L1013 (1999) 8.5.1 Standard Time Test. The sample was measured using a Tensilon UCT-100 manufactured by Orientec Co., Ltd., with a gripping distance of 25 cm and a pulling speed of 30 cm / min. Tenacity was determined from the maximum strength in the S-S curve, and elongation was determined from the elongation at the point showing the maximum strength in the S-S curve, and tenacity was determined by dividing the strength by the total fineness.

[0055] (7) Number of fluffs in yarn production: The obtained fiber package was rewound at a speed of 150 m / min, and a laser fluff detector "Flytec V" manufactured by Heberlein was installed 2 m away from the yarn during rewinding, and the total number of fluffs detected was evaluated. The evaluation was carried out for 100,000 m or more, and the number was converted to the number per 10,000 m and displayed.

[0056] Example 1 Production of Virgin Nylon 66 Chips A 5 wt% aqueous solution of copper acetate was added as an antioxidant to nylon 66 chips obtained by liquid-phase polymerization and mixed to add and adsorb 68 ppm of copper relative to the polymer weight. Next, a 50 wt% aqueous solution of potassium iodide and a 20 wt% aqueous solution of potassium bromide were added and adsorbed in amounts of 0.1 part by weight of each to 100 parts by weight of the polymer chips, and solid-state polymerization was carried out using a batch-type solid-state polymerization apparatus to obtain nylon 66 chips with a relative viscosity in sulfuric acid of 3.75.

[0057] <Manufacturing of Material Recycled Nylon 66 Chips> Airbag rejects are recycled into N ２ The polymer was melted at 340°C in a pressure melter with an oxygen partial pressure of 50 Pa achieved by purging and evacuation, and the molten polymer was introduced into a single-screw extruder. The melt temperature in the extruder was 290°C, and the polymer was melted while maintaining a tip pressure of 8 MPa. The extrusion rate was adjusted so that the total melt filtration time was 5 minutes / kg. The filtered molten polymer was extruded from a nozzle, water-cooled, and cut to obtain recycled nylon 66 chips with a diameter of 1.2 mm and a length of 2.0 mm.

[0058] <Production of Material Recycled Nylon 66 Fiber> The resulting virgin nylon 66 chips and material recycled nylon 66 chips were weighed and mixed in the ratios listed in Table 1, then fed into a 110 mm diameter extruder and melted under vacuum at a melt temperature of 300°C. The molten polymer was discharged using a metering pump to adjust the discharge rate so as to obtain multifilaments with a total fineness of 470 dtex, and then placed in a spinning pack. The resulting mixture was then filtered through a metal nonwoven filter with a 15 μm roughness in the spinning pack and spun through a spinneret with 72 circular holes. A heating cylinder with a length of 15 cm was installed 3 cm below the spinneret surface, and heated to a cylinder ambient temperature of 250°C. The cylinder ambient temperature here refers to the air temperature at the center of the heating cylinder length, 1 cm away from the inner wall. A uniflow chimney for blowing air from one direction was attached directly below the heating cylinder, and cold air at 20°C was blown onto the yarn at a speed of 35 m / min to cool and solidify it, after which an oil agent was applied to the yarn.

[0059] The undrawn yarn to which the oiling agent had been applied was wound around the 1FR rotating at a surface speed of 818 m / min and taken up, and then drawn at a total draw ratio of 4.5x. The taken-up yarn was continuously stretched by 5% between the take-up roller and the 2FR without being taken up once, and then subsequently subjected to a first-stage drawing at a rotational speed ratio of 2.80x and a second-stage drawing at a rotational speed ratio of 1.46x, and then taken up at a speed of 3358 m / min. The roller surfaces of the 1FR and 2FR were mirror-finished, while the 1DR, 2DR, and RR were matte-finished. The roller temperatures were as follows: 1FR was unheated, 2FR was 40°C, 1DR was 150°C, 2DR was 225°C, and RR was 150°C. Material recycled nylon 66 fiber was obtained by this melt spinning and drawing. The entanglement treatment was carried out by injecting high-pressure air perpendicular to the running yarn in the entanglement device. Guides for regulating the running yarn were provided before and after the entanglement device, and the pressure of the injected air was kept constant at 0.4 MPa.

[0060] Example 2 The same procedure as in Example 1 was carried out except that the raw material of recycled nylon 66 chips was changed to waste from the fiber manufacturing process, the total draw ratio was changed to 4.8 times, and the proportion of recycled chips was changed to 100%.

[0061] (Example 3) The same procedure as in Example 1 was carried out, except that the raw material for the recycled nylon 66 chips was changed to waste selvage of an airbag base fabric, the total draw ratio was changed to 4.6 times, the ratio of recycled chips was changed to 50%, and the total fineness of the recycled nylon 66 fiber was changed to 110 dtex.

[0062] (Example 4) The same procedure as in Example 1 was carried out, except that the raw material for the recycled nylon 66 chips was airbag cutting and sewing waste, the total draw ratio was 5.8 times, the draw speed was 2645 m / min, the ratio of recycled chips was 5%, and the total fineness of the recycled nylon 66 fiber was 1400 dtex.

[0063] (Example 5) The same procedure as in Example 1 was carried out except that the raw material of the recycled nylon 66 chips was recycled airbags from scrapped automobiles, the total draw ratio was 5.7 times, the draw speed was 2050 m / min, and the total fineness of the recycled nylon 66 fibers was 2100 dtex.

[0064] (Example 6) The same procedure as in Example 1 was carried out, except that the raw material for the material recycled nylon 66 chips was base fabric scraps from the scouring process, the melting atmosphere during the production of the material recycled nylon 66 chips was vacuum, and the total fineness of the material recycled nylon 66 fibers was 350 dtex.

[0065] Comparative Example 1 The same procedure as in Example 1 was carried out except that the ratio of raw material chips used was changed to 100% virgin chips and the total stretching ratio was changed to 4.4 times.

[0066] Comparative Example 2 The same procedure as in Example 1 was carried out except that the atmosphere in the molten part during the production of the material recycled nylon 66 chips was changed to ordinary air.

[0067] Comparative Example 3 The same procedure as in Example 1 was carried out except that the moisture content of the raw material recycled nylon 66 chips was set to 49,000 ppm and the proportion of recycled chips was set to 100%.

[0068] Comparative Example 4 The same procedure as in Example 1 was carried out except that the moisture content of the raw material recycled nylon 66 chips was set to 150,000 ppm and the proportion of recycled chips was set to 100%.

[0069]

[0070] The physical properties of the virgin nylon 66 fiber obtained in Comparative Example 1 and the material recycled nylon 66 fibers obtained in Examples 1 to 6 and Comparative Examples 2 to 4 were evaluated, and the results are shown in Table 1.

[0071] As is clear from Table 1, the material recycled nylon 66 fiber of the present invention has the same strength and elongation as virgin nylon 66 fiber, but has good fluff quality.

[0072] In Examples 1 to 5, the material recycled nylon 66 fibers of the present invention were produced by varying the type of recycled raw material, the proportion of material recycled nylon 66, and the total fiber fineness, but in all cases, the yarn properties were comparable to those of virgin nylon 66 fibers.

[0073] Furthermore, when the pre-melting atmosphere during the production of recycled nylon 66 chips was changed to a vacuum as in Example 6, the moisture contained in the recycled raw material was removed, resulting in an increase in chip viscosity, but the UVA value did not deteriorate, and the recycled fiber still had yarn properties equivalent to those of virgin fiber. On the other hand, when the pre-melting atmosphere during the production of recycled nylon 66 chips was changed to air as in Comparative Example 2, the UVA value deteriorated, and it can be seen that the strength, elongation, and fluff quality of the raw yarn were worse than those of virgin fiber.

[0074] Furthermore, when the moisture content of the process waste used to make the recycled nylon 66 chips exceeds 30,000 ppm, as in Comparative Examples 3 and 4, the UVA value of the chips deteriorates, and as a result, the strength and elongation of the raw yarn deteriorates compared to virgin fiber.

[0075] These results suggest that reducing the oxygen partial pressure in the pre-melting atmosphere during the production of recycled nylon 66 chips and keeping the moisture content of the process waste, which is the raw material for recycled nylon 66 chips, within a specified range are important for producing recycled nylon 66 fibers with high strength and good fluff quality that are suitable for industrial applications.

[0076] The material recycled nylon 6,6 fiber of the present invention has high strength and good fluff quality, and is therefore suitable for use in sustainable industrial materials such as airbags and tire cords.

[0077] 1: Spinneret 2: Heating barrel 3: Cross-flow cooler 4: Oil supply device 5: Yarn 6: Take-up roller (1FR) 7: Yarn feed roller (2FR) 8: First drawing roller (1DR) 9: Second drawing roller (2DR) 10: Relaxation roller (RR) 11: Winder

Claims

1. Recycled nylon 66 fiber containing 5% by weight or more of recycled nylon 66 and having 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 0.30 or less.

3. The recycled nylon 66 fiber according to claim 1 or 2, characterized in that the number of fuzz particles is 0 to 3 pieces / 10,000 m.

4. The recycled nylon 66 fiber according to any one of claims 1 to 3, which is produced from repellentized chips using any one or more of the following raw materials: waste from the textile manufacturing process, waste airbag base fabric edges, waste base fabric from scouring processing, waste airbag rejected products, waste airbag cutting and sewing, and airbags collected from scrapped automobiles.

5. A fabric for an airbag, comprising the recycled nylon 66 fiber according to claim 1 or 2.

6. A tire cord using the recycled nylon 66 fiber according to claim 1 or 2.

7. A racket string using the recycled nylon 66 fiber according to claim 1 or 2.

8. A V-ribbed belt using the recycled nylon 66 fiber according to claim 1 or 2.

9. A fabric for bags, comprising the recycled nylon 66 fiber according to claim 1 or 2.

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