A method for preparing spinning-grade nylon 6 regenerated chips

Abstract

This invention discloses a method for preparing spinning-grade recycled nylon 6 chips. The method involves collecting and crushing waste nylon 6 fibers or materials; then conveying them to a first bath for high-temperature steam cleaning; followed by a second pretreatment bath for high-pressure rinsing and ultrasonic cleaning to remove remaining impurities from the raw material surface; then dehydrating the pretreated material using a centrifuge in a "low-speed + high-speed" mode; finally, crystallizing the raw material; and finally granulating it into spinning-grade recycled nylon 6 chips. This method ensures that the granulated chips meet spinning-grade standards and can be directly used for spinning fine denier porous yarns.

Description

Technical Field

[0001] The invention relates to a method for preparing a spinning-grade nylon 6 regenerated slice, and belongs to the technical field of textiles. Background Art

[0002] In the production process of nylon 6, some waste products will be generated in each process. These waste products may exist in various forms, from solid waste blocks to DTY waste yarns with good fluffiness. The total amount of these waste products accounts for 3%-6% of the total output of nylon 6, causing great economic losses to the company and also posing great pressure on the entire social environment. However, with the development of engineering technology and the continuous advancement of technology, as well as the gradual improvement of environmental protection requirements, the treatment of nylon 6 waste yarn has become more diverse, such as modification for engineering plastics or professional chemical depolymerization to re-prepare CPL, or directly used for filling for industrial purposes; in recent years, some universities and other research institutions have directly recycled and granulated nylon 6 waste yarns, and also used them for spinning, but the final ideal result can only be used in coarse denier or industrial yarns, which can neither meet the requirements of slicing for the production of fine denier porous yarns, nor can the economic value of this part be excavated. In addition, due to the limitations of the technology, it has not been promoted and applied in factories. Summary of the invention

[0003] The purpose of the present invention is to provide a method for preparing spinning-grade nylon 6 regenerated chips, wherein the obtained spinning-grade nylon 6 regenerated chips can be directly used for spinning and can produce fine-denier porous yarns of the same quality as normal chips.

[0004] To achieve the above object, the present invention adopts the following technical solution:

[0005] A method for preparing a spinning-grade nylon 6 regenerated chip comprises the following steps:

[0006] The first process: raw material preparation stage

[0007] According to the various waste silks and waste materials such as nylon FDY / HOY / POY / DTY in the production sites of each workshop, whether oily or oil-free, they can be used as raw materials and concentrated at the equipment inlet for crushing. Considering the influence of temperature and humidity on the crystallinity of nylon 6, the front and rear shredder blades are made of cold steel forging materials, plus air cooling to prevent the temperature of the blade from rising after long-term work, resulting in oxidation and denaturation of nylon 6 waste silk; ensure that the waste silk only undergoes physical changes after being cut in two ways, and maintains the original crystallization unchanged; the main control parameters of this link process are: temperature control at 30-70℃, raw material crushing length L is 2-6mm (the length of a single piece of waste silk or waste block after being chopped).

[0008] The second process: raw material pretreatment process

[0009] First pretreatment

[0010] After two crushing / shredding processes in the first process, the waste silk or waste blocks have become smaller units. Through the positive air pressure of the blower, the agglomerated raw materials are concentrated and blown to the first bath through the U-shaped pipe. In the first bath, they are evenly spread on the plate chain through the plate conveyor chain. While the raw materials are transported forward, the high-pressure and high-temperature steam under the plate chain is sprayed upward through the holes in the bottom plate of the plate chain, so that impurities such as grease and low-boiling monomers on the surface of the raw materials evaporate; in order to ensure that the raw materials do not undergo large crystallization under high-temperature steam, a high-pressure pure water spray head is also arranged on the plate conveyor chain, which is arranged at intervals with the high-pressure steam spray position, and repeatedly washes the raw materials passing through "up and down, high temperature and normal temperature". The plate chain also vibrates during the conveying process, which is more conducive to the sinking of large impurities and falling through the holes on the plate chain. At the end of the plate conveyor chain, there is also a pressure roller, and an adjustable gap is left between the pressure roller and the plate of the plate chain to squeeze the moisture in the raw materials passing through. The steam and other exhaust gases generated in this process are sucked away by the negative pressure cover above the bathing device and discharged to the outside after being treated by the exhaust gas treatment device. The main control parameters of this process are: high-pressure steam temperature T1 is 120-140℃, high-pressure steam pressure P1 is 1.2-2.2Pa, plate chain conveying speed V1 is 10-30cm / min, and high-pressure pure water injection pressure P2 is 1.2-2.2Pa.

[0011] Second pretreatment

[0012] After the first pretreatment, the raw materials with less water content are directly transported to the second pretreatment bath. The bottom of the second cleaning box also uses a plate conveyor chain, which circulates and transports the fragmented raw materials forward; there are many small holes on the plate, which is conducive to the fall of impurities. Below the plate conveyor chain, the difference is that 4 sections of ultrasonic vibration cleaners are arranged below; above the plate conveyor chain, multiple high-pressure spray nozzles are arranged to spray pure water downward to rinse the passing raw materials. This link adopts the flushing form of "high-pressure pure water spray on the top and 4 sections of ultrasonic vibration cleaner on the bottom" to clean the remaining impurities on the surface of the raw materials again. The plate chain also vibrates during the conveying process, which is more conducive to the sinking of larger impurities and falling through the holes on the plate chain. This link controls the weight ratio of water to raw materials, that is, the bath ratio. At the end of the plate conveyor chain, there is also a pressing roller, and an adjustable gap is left between the pressing roller and the plate of the plate chain to squeeze the water in the passing raw materials. This process is an important treatment process for raw materials to reach spinning grade slices; this process does not generate steam, and the wastewater generated is returned to the sewage treatment equipment through the water pipe for treatment and then discharged into the sewage pipe network. The main control parameters of this process are: plate chain conveying speed V2 is 120-140cm / min, high-pressure pure water injection pressure P3 is 1.2-2.2Pa, ultrasonic oscillation frequency f1 is 25-130KHz, f2 is 50-60KHz, f3 is 40-80KHz, f4 is 25-130KHz, and the weight ratio of raw materials to water is above 1:25.

[0013] Raw material water treatment

[0014] This process uses a centrifuge, and the centrifugal filtration effect of the centrifuge is used to make the centrifugal pressure generated by the suspension under the centrifugal force field act on the filter medium, so that the liquid passes through the filter medium to become filtrate, and the solid particles are trapped on the surface of the filter medium, thereby achieving liquid-solid separation; this loop is controlled by electronic control, and the "low speed + high speed" mode is used to dehydrate the raw materials in steps. This step can reduce the fiber denaturation and large changes in crystallinity caused by friction. The main control parameters of this process are: low-speed dehydration time t1 is 10-60s, and high-speed dehydration time t2 is 10-60s.

[0015] The first pretreatment mentioned above evaporates impurities such as grease and low-boiling monomers on the surface of the raw materials. In order to ensure that the raw materials do not undergo significant crystallization under high-temperature steam, vibration is also applied during transportation, which is more conducive to the sinking of larger impurities and achieves the effects of preliminary oil removal, impurity removal, and cleaning.

[0016] The second pretreatment further processes the remaining tiny impurities on the surface of the raw materials, making the raw materials even cleaner and minimizing the impact of the remaining small impurities on product quality;

[0017] The raw material water filtration treatment adopts the "low speed + high speed" mode to dehydrate the raw materials in steps. This step can reduce the water content of the raw materials, basically drying most of the water, and the whole process is energy-saving. It can also reduce the fiber denaturation and large changes in crystallinity caused by friction.

[0018] The third process: raw material crystallization treatment

[0019] The raw material obtained in step (2) is transported to a high temperature box, which is divided into three stages: dehumidification, drying, and balancing. The dehumidification stage is at 100-190°C for 20-50s to remove most of the moisture in the raw material to facilitate subsequent drying; the drying stage is at 150-210°C for 6-15s to dry the raw material on the basis of dehumidification, with a moisture content of 0.05%-0.12%; the balancing stage is at 85-100°C for 10-50s to fully rehydrate the raw material on the basis of drying, achieve internal and external balance, and achieve crystallization treatment, with a moisture content of 0.03%-0.06%. The treated raw material is stored in a tank filled with nitrogen. Direct drying to the target moisture content will lead to unstable raw material performance. The most direct manifestation is that the AA rate (full roll rate) in the subsequent spinning process is only 88%-93%. After drying and then balancing, the raw material performance is relatively stable, and the full roll rate is basically maintained at 94-97%, which is close to the spinning condition of normal slices (the normal full roll rate of conventional raw materials is maintained at more than 95%).

[0020] The fourth process: granulation process

[0021] The product produced in the third step is used as raw material, and a complete set of processes including a granulating main machine, a stainless steel vacuum environmental protection machine, a granulating auxiliary machine, a filtering extruder, a stainless steel cooling water tank, a stainless steel air-cooled drying rack, a granulator, a vibrating screen, and a storage tank are used to produce nylon 6 chips in large and small granules; the chips in this step are then processed by a granulating dehumidification and drying system to reach the moisture content required by the process and can be directly used for downstream spinning.

[0022] The preparation method of the present invention mainly processes and controls the crystallization of raw materials. 1. The structure of synthetic fiber crystallization is often affected by supercrystallinity. Large grains usually reduce the elongation at break and toughness of fiber polymers. The tensile strength, modulus, elongation at break and toughness of small grain polymers are higher than those of large grain structure fibers, because there are more defects in the voids and crystal interfaces inside the large grains. 2. At different temperatures, the flexibility, aggregate structure and even the macroscopic morphology of fiber polymers will change to varying degrees, thereby affecting the molding and processing properties and use performance of the fibers. 3. The molecule of nylon 6, professionally known as polyamide 6 (molecular formula -NH-(CH2)5-CO-), is composed of multiple combinations of flexible chain methylene groups and connected by amide bonds -CONH-. Amide bond polar groups can form stable hydrogen bonds, which can not only make the molecules interact with each other to form crystal regions, but also can react with water molecules to form a certain hygroscopicity. The more the number of methylene groups, the more conformations, and the greater the molecular flexibility. Due to the characteristics of the two groups, polyamide molecules can easily form a steady-state structure, i.e. crystallization, through certain chain segment movement and hydrogen bonding. 4. The moisture content of nylon 6 affects the concentration of amine groups, which affects the viscosity of nylon 6 slices, and the viscosity directly affects the strength of the finished yarn.

[0023] The chips produced by the present invention meet the following index range of spinning-grade chips.

[0024] BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 It is a structural schematic diagram of the plate type conveyor chain of the present invention;

[0026] Figure 2 This is a schematic diagram of the structure of the first pretreatment equipment;

[0027] Figure 3 It is a schematic diagram of the second pre-processing structure;

[0028] In the figure: 1-pretreatment bath box, 2-plate conveyor chain, 3-high-pressure pure water jet head, 4-high-pressure and high-temperature steam equipment, 5-ultrasonic oscillation cleaner. DETAILED DESCRIPTION

[0029] In order to make the contents of the present invention easier to understand, the technical solution of the present invention is further described below in conjunction with specific implementation methods, but the present invention is not limited thereto.

[0030] Embodiment 1:

[0031] A method for preparing a spinning-grade nylon 6 regenerated chip comprises the following steps:

[0032] The first process: raw material preparation stage

[0033] According to the various waste silks and waste materials such as nylon FDY / HOY / POY / DTY in the production sites of each workshop, whether oily or oil-free, they can be used as raw materials and concentrated at the equipment inlet for crushing. Considering the influence of temperature and humidity on the crystallinity of nylon 6, the front and rear shredder blades are made of cold steel forging materials, plus air cooling to prevent the temperature of the blade from rising after long-term work, resulting in oxidation and denaturation of nylon 6 waste silk; ensure that the waste silk only undergoes physical changes after being cut in two ways, and maintains the original crystallization unchanged; the main control parameters of this link process are: temperature control at 30-70℃, raw material crushing length L is 2-6mm (the length of a single piece of waste silk or waste block after being chopped).

[0034] The second process: raw material pretreatment process

[0035] like Figure 1-3 As shown, the first bath and the second pretreatment bath are both provided with a pretreatment bath box 1, a plate conveyor chain 2 and a high-pressure pure water jet head 3, wherein the first bath is also provided with a high-pressure and high-temperature steam device 4, and the second pretreatment bath is also provided with an ultrasonic oscillation cleaner 5, and a plurality of holes are provided on the plate conveyor chain 2.

[0036] First pretreatment

[0037] After two crushing / shredding steps in the first process, the waste silk or waste blocks have become smaller units. Through the positive air pressure of the blower, the agglomerated raw materials are concentrated and blown to the first bath through the U-shaped pipe. In the first bath, they are evenly spread on the plate conveyor chain through the plate conveyor chain. While the raw materials are transported forward, the high-pressure and high-temperature steam under the plate conveyor chain is sprayed upward through the holes in the bottom plate of the plate conveyor chain, so that impurities such as grease and low-boiling monomers on the surface of the raw materials evaporate; in order to ensure that the raw materials do not undergo large crystallization under high-temperature steam, a high-pressure pure water spray head is also arranged on the plate conveyor chain, which is arranged at intervals with the high-pressure steam spray position, and repeatedly washes the raw materials passing through "up and down, high temperature and normal temperature". The plate chain also vibrates during the conveying process, which is more conducive to the sinking of large impurities and falling through the holes on the plate chain. At the end of the plate conveyor chain, there is also a pressure roller, and an adjustable gap is left between the pressure roller and the plate of the plate chain to squeeze the moisture in the passing raw materials. The steam and other exhaust gases generated in this process are sucked away by the negative pressure cover above the bathing device and discharged to the outside after being treated by the exhaust gas treatment device. The main control parameters of this process are: high-pressure steam temperature T1 is 120℃, high-pressure steam pressure P1 is 1.2Pa, plate chain conveying speed V1 is 30cm / min, and high-pressure pure water injection pressure P2 is 1.2Pa.

[0038] Second pretreatment

[0039] After the first pretreatment, the raw materials with less water content are directly transported to the second pretreatment bath. The bottom of the second cleaning box also uses a plate conveyor chain, which circulates and transports the fragmented raw materials forward; there are many small holes on the plate, which is conducive to the fall of impurities. Below the plate conveyor chain, the difference is that 4 sections of ultrasonic vibration cleaners are arranged below; above the plate conveyor chain, multiple high-pressure spray nozzles are arranged to spray pure water downward to rinse the passing raw materials. This link adopts the flushing form of "high-pressure pure water spray on the top and 4 sections of ultrasonic vibration cleaner on the bottom" to clean the remaining impurities on the surface of the raw materials again. The plate chain also vibrates during the conveying process, which is more conducive to the sinking of larger impurities and falling through the holes on the plate chain. This link controls the weight ratio of water to raw materials, that is, the bath ratio. At the end of the plate conveyor chain, there is also a pressing roller, and an adjustable gap is left between the pressing roller and the plate of the plate chain to squeeze the water in the passing raw materials. This process is an important treatment process for raw materials to reach spinning grade chips; this process does not generate steam, and the wastewater generated is returned to the sewage treatment equipment through the water pipe for treatment and then discharged into the sewage pipe network. The main control parameters of this process are: plate chain conveying speed V2 is 120cm / min, high-pressure pure water injection pressure P3 is 1.2Pa, ultrasonic oscillation frequency f1 is 25KHz, f2 is 50KHz, f3 is 40KHz, f4 is 25KHz, and the weight ratio of raw materials to water is 1:25.

[0040] Raw material water treatment

[0041] This process uses a centrifuge, and the centrifugal filtration effect of the centrifuge is used to make the centrifugal pressure generated by the suspension under the centrifugal force field act on the filter medium, so that the liquid passes through the filter medium to become filtrate, and the solid particles are trapped on the surface of the filter medium, thereby achieving liquid-solid separation; this loop is controlled by electronic control, and the "low speed + high speed" mode is used to dehydrate the raw materials in steps. This step can reduce the fiber denaturation and large changes in crystallinity caused by friction. The main control parameters of this process are: low-speed dehydration time t1 is 60s, and high-speed dehydration time t2 is 60s.

[0042] The third process: raw material crystallization treatment

[0043] The raw material obtained in step (2) is transported to a high temperature box, which is divided into three stages: dehumidification, drying, and balancing. The dehumidification stage is at 150°C for 40 seconds to remove most of the moisture in the raw material to facilitate subsequent drying; the drying stage is at 180°C for 9 seconds. On the basis of dehumidification, the raw material is made to reach a dry state with a moisture content of 0.05%-0.12%; the balancing stage is at 90°C for 30 seconds. On the basis of drying, the raw material is made to fully regain moisture, achieve internal and external balance, and achieve crystallization treatment with a moisture content of 0.03%-0.06%. The treated raw material is stored in a tank filled with nitrogen.

[0044] The fourth process: granulation process

[0045] The product produced in the third step is used as raw material, and a complete set of processes including a granulating main machine, a stainless steel vacuum environmental protection machine, a granulating auxiliary machine, a filtering extruder, a stainless steel cooling water tank, a stainless steel air-cooled drying rack, a granulator, a vibrating screen, and a storage tank are used to produce nylon 6 chips in large and small granules; the chips in this step are then processed by a granulating dehumidification and drying system to reach the moisture content required by the process and can be directly used for downstream spinning.

[0046] Embodiment 2:

[0047] A method for preparing a spinning-grade nylon 6 regenerated chip comprises the following steps:

[0048] The first process: raw material preparation stage

[0049] According to the various waste silks and waste materials such as nylon FDY / HOY / POY / DTY in the production sites of each workshop, whether oily or oil-free, they can be used as raw materials and concentrated at the equipment inlet for crushing. Considering the influence of temperature and humidity on the crystallinity of nylon 6, the front and rear shredder blades are made of cold steel forging materials, plus air cooling to prevent the temperature of the blade from rising after long-term work, resulting in oxidation and denaturation of nylon 6 waste silk; ensure that the waste silk only undergoes physical changes after being cut in two ways, and maintains the original crystallization unchanged; the main control parameters of this link process are: temperature control at 30-70℃, raw material crushing length L is 2-6mm (the length of a single piece of waste silk or waste block after being chopped).

[0050] The second process: raw material pretreatment process

[0051] like Figure 1-3 As shown, the first bath and the second pretreatment bath are both provided with a pretreatment bath box 1, a plate conveyor chain 2 and a high-pressure pure water jet head 3, wherein the first bath is also provided with a high-pressure and high-temperature steam device 4, and the second pretreatment bath is also provided with an ultrasonic oscillation cleaner 5, and a plurality of holes are provided on the plate conveyor chain 2.

[0052] First pretreatment

[0053] After two crushing / shredding processes in the first process, the waste silk or waste blocks have become smaller units. Through the positive air pressure of the blower, the agglomerated raw materials are concentrated and blown to the first bath through the U-shaped pipe. In the first bath, they are evenly spread on the plate chain through the plate conveyor chain. While the raw materials are transported forward, the high-pressure and high-temperature steam under the plate chain is sprayed upward through the holes in the bottom plate of the plate chain, so that impurities such as grease and low-boiling monomers on the surface of the raw materials evaporate; in order to ensure that the raw materials do not undergo large crystallization under high-temperature steam, a high-pressure pure water spray head is also arranged on the plate conveyor chain, which is arranged at intervals with the high-pressure steam spray position, and repeatedly washes the raw materials passing through "up and down, high temperature and normal temperature". The plate chain also vibrates during the conveying process, which is more conducive to the sinking of large impurities and falling through the holes on the plate chain. At the end of the plate conveyor chain, there is also a pressure roller, and an adjustable gap is left between the pressure roller and the plate of the plate chain to squeeze the moisture in the raw materials passing through. The steam and other exhaust gases generated in this process are sucked away by the negative pressure cover above the bathing device and discharged to the outside after being treated by the exhaust gas treatment device. The main control parameters of this process are: high-pressure steam temperature T1 is 140℃, high-pressure steam pressure P1 is 2.0Pa, plate chain conveying speed V1 is 20cm / min, and high-pressure pure water injection pressure P2 is 2.0Pa.

[0054] Second pretreatment

[0055] After the first pretreatment, the raw materials with less water content are directly transported to the second pretreatment bath. The bottom of the second cleaning box also uses a plate conveyor chain, which circulates and transports the fragmented raw materials forward; there are many small holes on the plate, which is conducive to the fall of impurities. Below the plate conveyor chain, the difference is that 4 sections of ultrasonic vibration cleaners are arranged below; above the plate conveyor chain, multiple high-pressure spray nozzles are arranged to spray pure water downward to rinse the passing raw materials. This link adopts the flushing form of "high-pressure pure water spray on the top and 4 sections of ultrasonic vibration cleaner on the bottom" to clean the remaining impurities on the surface of the raw materials again. The plate chain also vibrates during the conveying process, which is more conducive to the sinking of larger impurities and falling through the holes on the plate chain. This link controls the weight ratio of water to raw materials, that is, the bath ratio. At the end of the plate conveyor chain, there is also a pressing roller, and an adjustable gap is left between the pressing roller and the plate of the plate chain to squeeze the water in the passing raw materials. This process is an important treatment process for raw materials to reach spinning grade chips; this process does not generate steam, and the wastewater generated is returned to the sewage treatment equipment through the water pipe for treatment and then discharged into the sewage pipe network. The main control parameters of this process are: plate chain conveying speed V2 is 120cm / min, high-pressure pure water injection pressure P3 is 1.8Pa, ultrasonic oscillation frequency f1 is 30KHz, f2 is 60KHz, f3 is 70KHz, f4 is 30KHz, and the weight ratio of raw materials to water is 1:25.

[0056] Raw material water treatment

[0057] This process uses a centrifuge, and the centrifugal filtration effect of the centrifuge is used to make the centrifugal pressure generated by the suspension under the centrifugal force field act on the filter medium, so that the liquid passes through the filter medium to become filtrate, and the solid particles are trapped on the surface of the filter medium, thereby achieving liquid-solid separation; this loop is controlled by electronic control, and the "low speed + high speed" mode is used to dehydrate the raw materials in steps. This step can reduce the fiber denaturation and large changes in crystallinity caused by friction. The main control parameters of this process are: low-speed dehydration time t1 is 30s, and high-speed dehydration time t2 is 30s.

[0058] The third process: raw material crystallization treatment

[0059] The raw material obtained in step (2) is transported to a high temperature box, which is divided into three stages: dehumidification, drying, and balancing. The dehumidification stage is at 100°C for 50 seconds to remove most of the moisture in the raw material to facilitate subsequent drying; the drying stage is at 150°C for 15 seconds to make the raw material reach a dry state on the basis of dehumidification, with a moisture content of 0.05%-0.12%; the balancing stage is at 100°C for 50 seconds to make the raw material fully regain moisture on the basis of drying to achieve internal and external balance and crystallization treatment, with a moisture content of 0.03%-0.06%. The treated raw material is stored in a tank filled with nitrogen.

[0060] The fourth process: granulation process

[0061] The product produced in the third step is used as raw material, and a complete set of processes including a granulating main machine, a stainless steel vacuum environmental protection machine, a granulating auxiliary machine, a filtering extruder, a stainless steel cooling water tank, a stainless steel air-cooled drying rack, a granulator, a vibrating screen, and a storage tank are used to produce nylon 6 chips in large and small granules; the chips in this step are then processed by a granulating dehumidification and drying system to reach the moisture content required by the process and can be directly used for downstream spinning.

[0062] Embodiment 3:

[0063] A method for preparing a spinning-grade nylon 6 regenerated chip comprises the following steps:

[0064] The first process: raw material preparation stage

[0065] According to the various waste silks and waste materials such as nylon FDY / HOY / POY / DTY in the production sites of each workshop, whether oily or oil-free, they can be used as raw materials and concentrated at the equipment inlet for crushing. Considering the influence of temperature and humidity on the crystallinity of nylon 6, the front and rear shredder blades are made of cold steel forging materials, plus air cooling to prevent the temperature of the blade from rising after long-term work, resulting in oxidation and denaturation of nylon 6 waste silk; ensure that the waste silk only undergoes physical changes after being cut in two ways, and maintains the original crystallization unchanged; the main control parameters of this link process are: temperature control at 30-70℃, raw material crushing length L is 2-6mm (the length of a single piece of waste silk or waste block after being chopped).

[0066] The second process: raw material pretreatment process

[0067] like Figure 1-3 As shown, the first bath and the second pretreatment bath are both provided with a pretreatment bath box 1, a plate conveyor chain 2 and a high-pressure pure water jet head 3, wherein the first bath is also provided with a high-pressure and high-temperature steam device 4, and the second pretreatment bath is also provided with an ultrasonic oscillation cleaner 5, and a plurality of holes are provided on the plate conveyor chain 2.

[0068] First pretreatment

[0069] After two crushing / shredding processes in the first process, the waste silk or waste blocks have become smaller units. Through the positive air pressure of the blower, the agglomerated raw materials are concentrated and blown to the first bath through the U-shaped pipe. In the first bath, they are evenly spread on the plate chain through the plate conveyor chain. While the raw materials are transported forward, the high-pressure and high-temperature steam under the plate chain is sprayed upward through the holes in the bottom plate of the plate chain, so that impurities such as grease and low-boiling monomers on the surface of the raw materials evaporate; in order to ensure that the raw materials do not undergo large crystallization under high-temperature steam, a high-pressure pure water spray head is also arranged on the plate conveyor chain, which is arranged at intervals with the high-pressure steam spray position, and repeatedly washes the raw materials passing through "up and down, high temperature and normal temperature". The plate chain also vibrates during the conveying process, which is more conducive to the sinking of large impurities and falling through the holes on the plate chain. At the end of the plate conveyor chain, there is also a pressure roller, and an adjustable gap is left between the pressure roller and the plate of the plate chain to squeeze the moisture in the raw materials passing through. The steam and other exhaust gases generated in this process are sucked away by the negative pressure cover above the bathing device and discharged to the outside after being treated by the exhaust gas treatment device. The main control parameters of this process are: high-pressure steam temperature T1 is 140℃, high-pressure steam pressure P1 is 2.2Pa, plate chain conveying speed V1 is 20cm / min, and high-pressure pure water injection pressure P2 is 2.2Pa.

[0070] Second pretreatment

[0071] After the first pretreatment, the raw materials with less water content are directly transported to the second pretreatment bath. The bottom of the second cleaning box also uses a plate conveyor chain, which circulates and transports the fragmented raw materials forward; there are many small holes on the plate, which is conducive to the fall of impurities. Below the plate conveyor chain, the difference is that 4 sections of ultrasonic vibration cleaners are arranged below; above the plate conveyor chain, multiple high-pressure spray nozzles are arranged to spray pure water downward to rinse the passing raw materials. This link adopts the flushing form of "high-pressure pure water spray on the top and 4 sections of ultrasonic vibration cleaner on the bottom" to clean the remaining impurities on the surface of the raw materials again. The plate chain also vibrates during the conveying process, which is more conducive to the sinking of larger impurities and falling through the holes on the plate chain. This link controls the weight ratio of water to raw materials, that is, the bath ratio. At the end of the plate conveyor chain, there is also a pressing roller, and an adjustable gap is left between the pressing roller and the plate of the plate chain to squeeze the water in the passing raw materials. This process is an important treatment process for raw materials to reach spinning grade chips; this process does not generate steam, and the wastewater generated is returned to the sewage treatment equipment through the water pipe for treatment and then discharged into the sewage pipe network. The main control parameters of this process are: plate chain conveying speed V2 is 140cm / min, high-pressure pure water injection pressure P3 is 2.2Pa, ultrasonic oscillation frequency f1 is 100KHz, f2 is 60KHz, f3 is 80KHz, f4 is 100KHz, and the weight ratio of raw materials to water is 1:25.

[0072] Raw material water treatment

[0073] This process uses a centrifuge, and the centrifugal filtration effect of the centrifuge is used to make the centrifugal pressure generated by the suspension under the centrifugal force field act on the filter medium, so that the liquid passes through the filter medium to become filtrate, and the solid particles are trapped on the surface of the filter medium, thereby achieving liquid-solid separation; this loop is controlled by electronic control, and the "low speed + high speed" mode is used to dehydrate the raw materials in steps. This step can reduce the fiber denaturation and large changes in crystallinity caused by friction. The main control parameters of this process are: low-speed dehydration time t1 is 10s, and high-speed dehydration time t2 is 10s.

[0074] The third process: raw material crystallization treatment

[0075] The raw material obtained in step (2) is transported to a high temperature box, which is divided into three stages: dehumidification, drying, and balancing. The dehumidification stage is at 190°C for 20 seconds to remove most of the moisture in the raw material to facilitate subsequent drying; the drying stage is at 210°C for 15 seconds. On the basis of dehumidification, the raw material is made to reach a dry state with a moisture content of 0.05%-0.12%; the balancing stage is at 100°C for 10 seconds. On the basis of drying, the raw material is fully rehumidified to achieve internal and external balance and crystallization treatment, with a moisture content of 0.03%-0.06%. The treated raw material is stored in a tank filled with nitrogen.

[0076] The fourth process: granulation process

[0077] The product produced in the third step is used as raw material, and a complete set of processes including a granulating main machine, a stainless steel vacuum environmental protection machine, a granulating auxiliary machine, a filtering extruder, a stainless steel cooling water tank, a stainless steel air-cooled drying rack, a granulator, a vibrating screen, and a storage tank are used to produce nylon 6 chips in large and small granules; the chips in this step are then processed by a granulating dehumidification and drying system to reach the moisture content required by the process and can be directly used for downstream spinning.

[0078] The above description is only a preferred embodiment of the present invention. All equivalent changes and modifications made according to the scope of the patent application of the present invention should fall within the scope of the present invention.

Claims

1. A method for preparing a spinning-grade nylon 6 regenerated chip, characterized in that: The steps include: (1) Raw material preparation stage: nylon 6 waste yarn or waste materials are collected and crushed; (2) Raw material pretreatment process: 1) First pretreatment: The raw material after crushing in step (1) is transported to the first bath for high-temperature steam impurity removal treatment; 2) Second pretreatment: After the first pretreatment, the raw material with less water content is directly transported to the second pretreatment bath for high-pressure washing and ultrasonic vibration cleaning, and the remaining impurities on the surface of the raw material are cleaned again; 3) Raw material water filtration treatment: The raw material after the second pretreatment is dehydrated in a "low speed + high speed" mode using a centrifuge; (3) Raw material crystallization treatment: the raw material obtained in step (2) is subjected to three-stage treatment of dehumidification, drying and balancing; (4) pelletizing the raw material obtained in step (3) to obtain regenerated nylon 6 chips; The first pretreatment in step (2) is specifically to concentrate the raw materials crushed in step (1) and blow them into the first bath through a U-shaped pipe. In the first bath, the raw materials are evenly spread on the plate conveyor chain through the action of the plate conveyor chain. While the raw materials are transported forward, the high-pressure and high-temperature steam under the plate conveyor chain is sprayed upward through the holes in the bottom plate of the plate conveyor chain to evaporate the grease and low-boiling-point monomer impurities on the surface of the raw materials. In order to ensure that the raw materials do not undergo large crystallization under the high-temperature steam, a high-pressure pure water spray head is also arranged on the plate conveyor chain, which is arranged at intervals with the high-pressure steam spray position to repeatedly rinse the raw materials passing through; The second pretreatment in step (2) is specifically that after the first pretreatment, the raw materials with less water content are directly transported to the second pretreatment bath, and the bottom of the second cleaning box also adopts a plate conveyor chain, which circulates and transports the raw materials forward. An ultrasonic vibration cleaner is arranged below the plate conveyor chain, and a plurality of high-pressure spray nozzles are arranged above the plate conveyor chain to spray pure water downward to rinse the raw materials passing through; The three-stage treatment of dehumidification, drying and balancing in step (3) is specifically as follows: the raw material obtained in step (2) is transported to a high-temperature box, which is divided into three stages: dehumidification, drying and balancing. The dehumidification stage is at 100-190°C for 20-50s to remove most of the moisture in the raw material to facilitate subsequent drying; the drying stage is at 150-210°C for 6-15s to dry the raw material on the basis of dehumidification, with a moisture content of 0.05%-0.12%; the balancing stage is at 85-100°C for 10-50s to fully rehydrate the raw material on the basis of drying, achieve internal and external balance, and achieve crystallization treatment, with a moisture content of 0.03%-0.06%.

2. The method for preparing the spinning-grade nylon 6 regenerated chips according to claim 1, characterized in that: The pulverization process in step (1) is specifically carried out through two pulverization steps. The front and rear pulverizer blades are both made of cold steel forging materials, and are cooled by air to prevent the blades from overheating after long-term operation, thereby preventing the nylon 6 waste from oxidizing and degenerating. This ensures that only physical changes occur to the waste silk after the waste silk is cut through the two steps, and the original crystal structure remains unchanged. The length of the waste silk after pulverization is 2-6 mm.

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