Method for preparing polyester industrial filament by using recycled polyester chips recycled from bottles and prepared polyester industrial filament

Abstract

The invention belongs to the field of chemical fibers, and particularly relates to a method for preparing polyester industrial filaments by using recycled polyester chips recycled from bottles and the prepared polyester industrial filaments, regenerated PET chips with the viscosity of 0.65-0.8 dl / g and the filtration value of 0-5 MPa are selected, 1.0-1.3 dl / g regenerated high-viscosity chips are obtained after tackifying, and spinning is carried out on an existing industrial filament production line; the temperature of a screw is controlled to be 280-330 DEG C, and the lengths of a feeding section and a metering section are adjusted, so that the slices are fully melted, meanwhile, it is ensured that a large amount of melt is not degraded due to the fact that the melt contains IPA, and the stability of the outlet pressure of the screw is ensured; a spinning assembly adopts a multi-layer metal filter screen structure of 5-30 [mu] m, so that the problem that the spinning assembly is quickly boosted due to many impurities of regenerated slices is solved; and the stretching and setting conditions are optimized and adjusted, so that the physical property, broken filaments and spinnability can meet the requirements.

Description

Technical Field

[0001] The invention belongs to the field of chemical fibers, and particularly relates to a method for preparing polyester industrial filaments by using recycled polyester chips from bottles and the prepared polyester industrial filaments. Background Art

[0002] With the implementation of carbon peak and carbon neutrality policies and the deepening of the concept of sustainable development, recycled bottle flakes will be returned to spinning products, opening up a new way to reuse discarded polyester bottles. In recent years, the technology of spinning recycled polyester staple fibers from waste PET bottle flakes has almost matured, and the market demand for various types of recycled polyester industrial yarns is also large. Due to the difference in the characteristics of PET bottle flakes and virgin polyester chips, the spun filaments must achieve continuous and uninterrupted high-speed spinning, and the requirements for raw materials and processes are higher than the technical level of spinning recycled polyester staple fibers.

[0003] Waste PET bottles are separated, crushed, washed and dried for re-granulation. Recycled PET bottle flakes contain impurities such as PVC, HDPE, and aluminum, which are the key factors affecting the color of PET. Recycled slices contain IPA, small molecules, impurities, etc. The strength of the prepared regenerated silk is lower than that of the original silk.

[0004] In the process of preparing polyester industrial filaments from virgin chips, a three-layer filtration structure is used in the spinning assembly, with a felt net in the middle and supported by sieve plates at the top and bottom. In the process of preparing polyester industrial filaments from recycled chips, there are relatively many impurities, and the melt has a greater impact on the filter net, resulting in clogging of the filtration structure and rapid pressure increase of the spinning assembly; the orifice expansion phenomenon is prone to occur during the spinning process, resulting in more spinning sticky plates, hairy fibers, and injection head fibers.

[0005] Technical issues that need to be solved:

[0006] 1) How to screen recycled polyester chips from bottles and eliminate abnormalities before spinning;

[0007] 2) Select the appropriate solid phase adhesion process;

[0008] 3) Ensure that physical properties, hair quality and other indicators are qualified by selecting appropriate melting, spinning, cooling and stretching processes;

[0009] 4) Since automotive products have high requirements for color value, it is necessary to study the control methods for the color value of automotive products. Summary of the invention

[0010] In view of the deficiencies in the prior art, the object of the present invention is to provide a method for preparing polyester industrial filaments using recycled polyester chips and the prepared polyester industrial filaments.

[0011] In order to solve the above technical problems, the technical solution adopted by the present invention is: a method for preparing polyester industrial filaments by recycling recycled polyester chips from bottles, comprising the following steps:

[0012] Step 1, placing bottle recycled polyester chips with a viscosity of 0.65-0.8 dl / g and a filtration value of 0-5 MPa, and a certain amount of original chips in an intermittent solid phase polymerization reactor, and uniformly raising the temperature in the intermittent solid phase polymerization reactor to 150-180° C. and heating for 2-12 hours under a vacuum degree of 10-15 Pa to obtain pre-crystallized chips; continuing to uniformly raise the temperature in the intermittent solid phase polymerization reactor to 180-220° C. and continue heating for 20-40 hours, so that the viscosity of the bottle recycled polyester chips is increased to 1.0-1.3 dl / g through solid phase polymerization, forming regenerated high-viscosity chips;

[0013] Step 2, conveying the regenerated high-viscosity slices to a screw extruder, and extruding the melt through the screw extruder, wherein the screw outlet temperature of the screw extruder is ≥280° C.; the length ratio of the feed section, the melting section, and the metering section in the screw extruder is 1: (1.0-3.0): (1.0-4.0);

[0014] Step 3, the melt extruded by the screw extruder is distributed to the spinning manifold to form a spinning melt, and the spinning melt is ejected from the spinneret after filtering at 295-305°C to obtain a melt flow; the filtering accuracy is 5-30 μm;

[0015] Step 4, slowly cooling the melt flow, and then cooling the melt flow by ring blowing or side blowing to obtain a wire body;

[0016] Step 5, after the cooled filament body enters the spinning tunnel, it is stretched, shaped and wound to obtain polyester industrial filament prepared from recycled polyester chips, wherein the parameters for stretching and shaping are: a pulling speed of 300 to 4000 m / min, oiling the surface of the filament body before stretching and shaping; a total stretching multiple of 1.0 to 6.5; a shaping temperature of 230°C to 260°C; a total relaxation rate of 1.6 to 9%, and winding is performed at a winding speed of 2000 to 7000 m / min to obtain polyester industrial filament prepared from recycled polyester chips recycled from bottles.

[0017] In a preferred embodiment, bottle recycled polyester chips and virgin chips constitute the overall chips, and the mass proportion of bottle recycled polyester chips in the overall chips is ≥10wt% and ≤100wt%; a certain amount of virgin chips refers to the mass proportion of virgin chips in the overall chips is ≥0wt% and ≤90wt%.

[0018] Preferably, the length ratio of the feed section, melting section and metering section in the screw extruder is 1: (1.5-2.5): (2.5-4). More preferably, the length ratio of the feed section, melting section and metering section in the screw extruder is 1: (1.8-2.2): (2.8-4).

[0019] Furthermore, in step 4, the slow cooling treatment is completed by a heating hood with a temperature of 300-350°C and an insulating cylinder with a height of 50-500mm; the ring blowing temperature is 50-70°C, the dynamic pressure is 0.02-0.06kPa, and the humidity is 50-70%; the side blowing temperature is 18-25°C, the wind speed is 0.4-0.6m / s, and the humidity is 50-70%.

[0020] In a preferred embodiment, in step 3, a multi-layer metal filter is used, the filtering accuracy of the multi-layer metal filter decreases layer by layer along the traveling direction of the spinning melt, and the spinning melt is evenly distributed to the spinneret holes.

[0021] Furthermore, the polyester industrial filament prepared by recycling the recycled polyester chips from bottles has a fineness of 167 to 3300 dtex.

[0022] Preferably, the polyester industrial filament prepared from recycled polyester chips from bottles has a breaking strength of ≥6.0 cN / dtex.

[0023] Furthermore, the polyester industrial filament prepared by using recycled polyester chips from bottles has a breaking strength variation coefficient of ≤4.0%.

[0024] Preferably, in step 3, the ratio of the micropore channel length of the spinneret hole to the diameter of the spinneret hole is 1.0 to 3.0.

[0025] Furthermore, the polyester industrial filament prepared from the recycled polyester chips from bottles has an elongation at break of 7-33%.

[0026] Preferably, the polyester industrial filament prepared from recycled polyester chips from bottles has an intermediate elongation of 5-20%.

[0027] Due to the high viscosity and low melting point of recycled bottle chips, 0.65-0.8dl / g recycled PET chips were selected, and 1.0-1.3dl / g recycled viscosity chips were obtained after viscosity enhancement, and spun on the existing industrial yarn production line; the screw temperature was controlled at 280-330℃ to fully melt the chips while ensuring that the melt was not degraded in large quantities due to the presence of IPA, and to ensure the stability of the screw outlet pressure; the spinning assembly used a 5-30μm multi-layer metal filter structure to improve the problem of fast pressure rise of the spinning assembly due to the large number of impurities in the recycled chips; the stretching and shaping conditions were optimized and adjusted so that the physical properties, hair and spinnability could meet the requirements. The production process parameters suitable for recycled chips were summarized, which can stably regenerate polyester industrial filaments, and the various indicators of recycled polyester industrial filaments are close to those of original filaments of the same specifications.

[0028] Another object of the present invention is to provide polyester industrial filaments obtained by the aforementioned method of preparing polyester industrial filaments using bottle recycled polyester chips.

[0029] Furthermore, the polyester industrial filament is used to prepare tire cord fabric, safety belts, air bags or sewing threads.

[0030] Compared with the prior art, the present invention has the following beneficial effects:

[0031] 1. After the bottle recycling chips are melted, the melt viscosity is high, the impurities are high, and they are easy to degrade. During the spinning process, the orifice expansion phenomenon is prone to occur, resulting in many spinning sticky plates, hairy fibers, and injection head fibers. According to the melt characteristics of the bottle chips, a pre-spinning filtration value test is designed to eliminate abnormal influences: After experimental research, 1kg of bottle recycling chips are used each time to carry out the filtration value (also called pressure filtration difference: under specified conditions, the chips are melted and extruded by a single-screw extruder, and the difference between the maximum pressure value before the head filter and the initial pressure value, where the speed frequency of the single-screw extruder is 10Hz) test. If the filtration value meets 0-5MPa, it can be used for chip spinning; if the filtration value is higher than 5MPa, it will cause abnormal pressure increase of the spinning component, resulting in spinning breakage, hairy fibers, and low product line density. In severe cases, normal production cannot be achieved.

[0032] 2. Since the waste PET bottles are separated, crushed, washed and dried for re-granulation during the preparation of bottle recycling slices, the recycled PET contains impurities such as PVC, HDPE, and aluminum. The presence of impurities is a key factor affecting the color of PET. Automotive products have relatively high requirements for color values, so the problem is solved from two aspects: a. Control the vacuum degree of the solid-phase viscosity increase drum to make the vacuum degree as small as possible. On the one hand, it can increase the reaction rate and reduce the reaction time. On the other hand, it can reduce the contact between the slices and oxygen to reduce the change in color value caused by the reaction of impurities in the recycled PET with oxygen; b. The solid-phase viscosity increase temperature uses a temperature below 220°C for the viscosity increase reaction. Using too high a temperature will cause the slices to oxidize and turn yellow; c. Add the process of knitting, dyeing, and color judgment, knit and dye the standard samples together with the recycled products produced each time, and use the recycled products without color difference in automotive products;

[0033] 3. According to experimental research, compared with virgin slices, the weight of 100 grains of bottle recycled slices is 1.1 to 1.3 times that of virgin slices, while the melting point is 4 to 7°C lower than that of virgin slices, and the characteristic viscosity is 0.06 to 0.1 dl / g higher than that of virgin slices. Therefore, when using bottle recycled slices for spinning, the length of each functional zone of the screw used should be different from that of virgin slices for spinning. According to the bulk density and melting time of bottle recycled slices after drying, by optimizing the length of each functional section (feeding section, melting section and metering section, increasing the length of melting section and metering section, and reducing the length of feeding section), the stability of screw extrusion volume and extrusion pressure can be guaranteed, thereby ensuring the normal spinning production.

[0034] The softening point and melting point of bottle recycled chips are lower than those of virgin chips, and the crystallinity after drying is also lower than that of virgin chips, so the melting temperature and time are lower than those of virgin chips. In addition, due to the complex composition of bottle recycled chips, the melting rates of different components and particles of different shapes vary greatly. Therefore, compared with the spinning of virgin chips, the melting process of bottle recycled chips should adopt relatively mild melting conditions, that is, appropriately lengthen the melting section or metering section to extend the residence time (increase viscosity to improve the mechanical properties of recycled polyester filament), and appropriately reduce the temperature of the melting section and metering section to reduce melt degradation. According to the above-mentioned differences in the characteristics of bottle recycled chips and virgin chips, the length of the metering section can also be appropriately increased to increase its residence time, effectively stabilize the screw extrusion pressure, and also play an important role in stabilizing spinning.

[0035] 4. The spinning melt of recycled bottle thickening slices has high viscosity (0.06-0.1dl / g higher than the original material), many impurities, and easy degradation. The orifice expansion phenomenon is easy to occur during the spinning process, resulting in many spinning sticky plates, hairy fibers, and injection head fibers. According to the characteristics of the spinning melt of recycled bottle thickening slices, suitable component filter elements and multi-layer metal filter structures are designed to improve the problem of fast component pressure increase caused by many impurities in the recycled slices, reduce the shear rate of the melt passing through the spinneret hole, significantly suppress the expansion phenomenon, greatly reduce defects and injection head fibers, and greatly improve the spinnability. At present, the maximum spinning speed of bottle slices can reach 5600m / min, which has reached the same level as the direct spinning of the original melt.

[0036] 5. Through the control of the filtration value, characteristic viscosity, and viscosity increase of the regenerated chips, as well as the appropriate extension of the melting section and the metering section to extend the residence time, and the use of multi-layer metal filters, the performance parameters of the polyester industrial filament prepared from the regenerated chips are closer to those of the polyester industrial filament prepared from the original chips. BRIEF DESCRIPTION OF THE DRAWINGS

[0037] Figure 1 Schematic diagram of the cross-sectional structure of a single hole of a spinneret;

[0038] Figure 2 It is a local structural diagram of the spinning assembly;

[0039] Among them, 1 is the spinning assembly, 2 is the spinning box, 3 is the heating cover, 4 is the spinneret, 5 is the insulation cylinder, a is the melt flow direction, b is the melt thin flow out direction, and c is the cooling air direction. DETAILED DESCRIPTION

[0040] The technical solution of the present invention is further described in detail below in conjunction with specific embodiments and drawings. It should be understood that the following embodiments are only used to explain the present invention and are not used to limit the present invention.

[0041] The present invention intends to select bottle recycled polyester chips with a characteristic viscosity (0.65-0.8dl / g), and then use a suitable viscosity-increasing process to increase the viscosity of the recycled chips to 1.0-1.3dl / g, design melting and cooling temperatures matching the recycled chips, obtain a stably extruded spinning melt, and optimize the stretching process parameters to obtain polyester industrial filaments prepared from bottle recycled polyester chips with qualified physical properties and hair fibers.

[0042] In order to further improve the mechanical properties of the yarn, the regenerated chips can be blended with the original chips in proportion and spun. When blending and spinning, the original chips with a viscosity of 0.655 to 0.68 dl / g are used.

[0043] A method for preparing polyester industrial filaments by recycling recycled polyester chips from bottles comprises the following steps:

[0044] Step 1, placing bottle recycled polyester chips with a viscosity (0.65-0.8 dl / g) and a filtration value (0-5 MPa) in an intermittent drum reactor (i.e., an intermittent solid phase polymerization reactor), rotating it under a vacuum degree of 10-15 Pa, and then heating the temperature in the reactor to 150-180° C. and heating it for 2-12 hours by heating the heat transfer oil pipe to obtain pre-crystallized chips, and then continuing to heat the temperature in the reactor to 180-220° C. by heating the heat transfer oil pipe, and continue heating for 20-40 hours, so that the viscosity of the bottle recycled chips is increased from 0.65-0.8 dl / g to 1.0-1.3 dl / g after solid phase polymerization, and forming high viscosity chips.

[0045] Filtration value: 1kg of regenerated chips are melt-extruded through a single-screw extruder, and the difference between the maximum pressure and the initial pressure before the die filter (3000 mesh woven mesh). The filtration performance test device includes a single-screw extruder (speed frequency 10Hz), a die filter and a pressure measuring component. The die filter refers to the filter on the feed side of the spinneret of the spinning assembly. The filtration performance test device simulates a real spinning scene; the melt extruded by the single-screw extruder passes through the filter, and then the pressure measuring component detects the difference between the maximum pressure and the initial pressure before the die filter.

[0046] Step 2: conveying the high-viscosity slices after solid phase polymerization to a screw extruder, and then extruding the melt through the screw extruder, wherein the screw diameter of the screw extruder is 75-170 mm, the screw aspect ratio is 24-33, and the screw outlet temperature is ≥280°C.

[0047] Step 3: The extruded melt is distributed to the melt pipes of each spinning box through the melt main pipe to form a spinning melt. The spinning melt enters the spinning assembly through a metering pump and is filtered through a filter screen in the spinning assembly. The melt is ejected from the spinneret to obtain a melt stream ( Figure 2 ). The spinning box 2 includes the metering pump and the spinning assembly, and the spinning assembly 1 includes a filter screen and a spinneret. The number of spinneret holes in the spinneret is 28-960; the ratio of the microporous channel length of the spinneret hole to the diameter of the spinneret hole is 1.0-3.0, such as Figure 1 As shown in , L1 is the microporous channel length, D1 is the spinneret diameter; the filter screen in the spinning assembly has a screen accuracy of 5 to 30 μm to improve the uniformity of the filament body. The spinning manifold is heated at a biphenyl temperature of 295 to 305°C to maintain good melt fluidity and pressure.

[0048] Step 4, after slow cooling treatment of each group of melt streams, cool the melt streams by ring blowing or side blowing to obtain the wire body. Among them, the temperature of the ring blowing is 50-70°C, the dynamic pressure is 0.02-0.06 kPa, and the humidity is 50-70%; the temperature of the side blowing is 18-25°C, the wind speed is 0.4-0.6 m / s, and the humidity is 50-70%. The slow cooling device includes a heating hood 3 and an insulation cylinder 5. The melt streams ejected from the spinneret 4 enter the heating hood and the insulation cylinder successively; the temperature control point of the heating hood is 300-350°C to maintain a good insulation effect. The function of the heating hood: to heat the internal air so that the melt stays in the hot air for a period of time and does not cool down rapidly. On the one hand, it can make the melt less likely to break; on the other hand, it can eliminate the internal stress of macromolecules and improve the tensile properties of fibers. An insulating cylinder 5 with a height of 50 to 500 mm is used, that is, the distance traveled by the melt stream in the insulating cylinder is 50 to 500 mm of the height of the insulating cylinder, so as to improve the phenomenon of large CV value of physical properties and many broken fibers caused by uneven cooling. The melt stream coming out of the insulating cylinder enters the ring blowing or side blowing device. The role of the insulating cylinder is to extend the length of the windless belt, on the one hand, reduce the impact of the airflow below on the spinneret and the unsolidified melt; on the other hand, it also plays a role in delaying cooling, so that the spinning stretching is completed before the melt solidifies, which is conducive to the formation of macromolecular straight chains and the uniformity of orientation of each part; its length is variable, which has a great influence on the elongation at break of the fiber.

[0049] Step 5, after the cooled filament body is put into the spinning tunnel for stretching, shaping and winding, the polyester industrial filament prepared from the recycled polyester chips from bottles is obtained, wherein the stretching and shaping parameters are: a pulling speed of 300 to 4000 m / min; oiling on the surface of the filament body; a total stretching multiple of 2.0 to 6.5; a shaping temperature of 230°C to 260°C; a total relaxation rate of 1.6 to 9%, and the winding is carried out at a winding speed of 2000 to 7000 m / min to obtain the polyester industrial filament prepared from the recycled polyester chips from bottles.

[0050] The polyester industrial filaments prepared from the recycled polyester chips from the bottles have a fineness of 100-3300 dtex;

[0051] The breaking strength of the polyester industrial filament prepared from the recycled polyester chips from the bottle is greater than or equal to 6.0 cN / dtex;

[0052] The coefficient of variation of the breaking strength of the polyester industrial filament prepared from the recycled polyester chips from the bottle is less than or equal to 4.0%;

[0053] The breaking elongation of the polyester industrial filament prepared from the bottle recycled polyester chips is 7-33%;

[0054] The intermediate elongation of the polyester industrial filaments prepared from the bottle recycled polyester chips is 5-20%.

[0055] Compared with polyester industrial filament made from 100% recycled polyester chips from bottles, which is made from 100% virgin PET chips, the carbon emissions are reduced by about 43%.

[0056] Polyester industrial filaments are prepared by recycling recycled polyester chips from bottles and can be used in the preparation of recycled tire cord fabrics, recycled sewing threads, recycled airbags, and recycled seat belts.

[0057] When it is used to prepare recycled tire cord fabric, the specific steps are:

[0058] Step 1, placing bottle recycled polyester chips with viscosity (0.65-0.8 dl / g) and filtration value (0-5 MPa) in an intermittent drum reactor, rotating it under a vacuum of 10-15 pa, and then heating the temperature in the reactor to 150-180° C. and heating it for 2-12 hours by heating the heat transfer oil pipe to obtain pre-crystallized chips, and then continuing to heat the temperature in the reactor to 210-220° C. by heating the heat transfer oil pipe, and continue heating for 25-40 hours, so that the viscosity of the bottle recycled chips is increased from 0.65-0.8 dl / g to 1.1-1.2 dl / g after solid phase polymerization, and high viscosity chips are formed.

[0059] Step 2, conveying the high-viscosity slices after solid phase polymerization to a screw extruder, and then extruding the melt through the screw extruder, wherein the screw diameter of the screw extruder is 75-170 mm, the screw aspect ratio is 24-33, the screw outlet temperature is ≥280°C, and the length ratio of the feed section, the melting section, and the metering section in the screw extruder is 1: (1.0-3.0): (1.0-4.0), the feed section temperature is 290-310°C, the melting section temperature is 300-320°C, and the metering section temperature is 290-310°C.

[0060] Step 3: The extruded melt is distributed to the melt pipes of each spinning box through the melt main pipe to form a spinning melt. The spinning melt enters the spinning assembly through a metering pump and is filtered through the filter in the spinning assembly. The melt is ejected from the spinneret to obtain a melt stream. The number of spinneret holes in the spinneret is 192-960; the ratio of the microporous channel length of the spinneret hole to the diameter of the spinneret hole is 1.0-3.0; the filter accuracy of the filter in the spinning assembly is 5-30 μm to improve the uniformity of the filament body. A biphenyl temperature of 295-305°C is used to maintain good melt fluidity and pressure.

[0061] Step 4: After the melt stream is subjected to slow cooling treatment, the melt stream is cooled by annular blowing to obtain the filament body. The annular blowing temperature is 50-70°C, the dynamic pressure is 0.02-0.06 kPa, the humidity is 50-70%, and the slow cooling treatment uses a heating hood with a temperature of 300-350°C and an insulation cylinder with a height of 50-120 mm.

[0062] Step 5: After the cooled filament body enters the spinning tunnel, it is stretched, shaped and wound to obtain polyester industrial filament prepared from bottle recycled polyester chips. Specifically, oil is applied on the surface of the filament body, and then stretched, shaped and wound; wherein the stretching and shaping is completed by 6 pairs of rollers; the first pair of rollers: the temperature is 80-95°C, the speed is 2700-3200 m / min, the second pair of rollers: the temperature is 90-100°C, the speed is 3700-4300 m / min / minute, the third, fourth and fifth pairs of rollers: temperature is 240-260°C, speed is 5600-6000 m / min, the sixth pair of rollers: no heating, speed is 5500-5900 m / min; the parameters of stretching and shaping are: total stretching multiple is 2.0-3.0; total relaxation rate is 2.0-5.0%, and winding shaping is carried out at a winding speed of 5000-6000 m / min to obtain polyester industrial filaments prepared from bottle recycled polyester chips.

[0063] The polyester industrial filaments prepared from the recycled polyester chips from the bottles have a fineness of 1100-3300 dtex;

[0064] The breaking strength of the polyester industrial filament prepared from the recycled polyester chips from the bottle is greater than or equal to 6.5 cN / dtex;

[0065] The coefficient of variation of the breaking strength of the polyester industrial filament prepared from the recycled polyester chips from the bottle is less than or equal to 3.0%;

[0066] The breaking elongation of the polyester industrial filament prepared from the recycled polyester chips from the bottle is 9-15%;

[0067] The intermediate elongation of the polyester industrial filament prepared from the bottle recycled polyester chips is 5-7%.

[0068] When it is used to prepare recycled sewing thread, the specific steps are:

[0069] Step 1, placing bottle recycled polyester chips with a viscosity (0.65-0.8 dl / g) and a filtration value (0-5 MPa) in an intermittent drum reactor, rotating it under a vacuum of 10-15 pa, and then heating the temperature in the reactor to 150-180° C. and heating it for 2-12 hours by heating the heat transfer oil pipe to obtain pre-crystallized chips, and then continuing to heat the temperature in the reactor to 180-220° C. by heating the heat transfer oil pipe, and continue heating for 20-35 hours, so that the viscosity of the bottle recycled chips is increased from 0.65-0.8 dl / g to 1.1-1.2 dl / g after solid phase polymerization, and high viscosity chips are formed.

[0070] Step 2, conveying the high-viscosity slices after solid phase polymerization to a screw extruder, and then extruding the melt through the screw extruder, wherein the screw diameter of the screw extruder is 75-170 mm, the screw aspect ratio is 24-33, the screw outlet temperature is ≥280°C, the length ratio of the feed section, the melting section, and the metering section in the screw extruder is 1: (1.0-3.0): (1.0-4.0), the feed section temperature is 280-300°C, the melting section temperature is 300-325°C, and the metering section temperature is 280-295°C.

[0071] Step 3: The extruded melt is distributed to the melt pipes of each spinning box through the melt main pipe to form a spinning melt. The spinning melt enters the spinning assembly through a metering pump and is filtered through the filter screen in the spinning assembly. The melt is ejected from the spinneret to obtain a melt stream. The number of spinneret holes in the spinneret is 28-144; the ratio of the microporous channel length of the spinneret hole to the diameter of the spinneret hole is 1.0-3.0; the filter screen accuracy of the filter screen in the spinning assembly is 5-30 μm to improve the uniformity of the filament body. A biphenyl temperature of 295-305°C is used to maintain good melt fluidity and pressure. Step 4: After the melt stream is slowly cooled, the melt stream is cooled by side blowing to obtain the filament body. The side blowing temperature is 18-25°C, the wind speed is 0.4-0.6m / s, and the humidity is 50-70%. During the slow cooling treatment, a heating hood with a temperature of 300 to 350°C and a heat-insulating cylinder with a height of 100 to 300 mm are used.

[0072] Step 5, after the cooled filament body enters the spinning tunnel, it is stretched, shaped and wound to obtain polyester industrial filament prepared from bottle recycled polyester chips. Specifically, oil is applied on the surface of the filament body, and then stretched, shaped and wound; wherein the stretching and shaping is completed by 5 pairs of rollers; the first pair of rollers: the temperature is 80-95°C, the speed is 350-550 m / min, the second pair of rollers: the temperature is 100-125°C, the speed is 350-550 m / min, the third pair of rollers: the temperature is 1 00~125℃, speed is 1400~1550 m / min, the fourth pair of rollers: temperature is 230~255℃, speed is 2400~2700 m / min, the fifth pair of rollers: no heating, speed is 2300~2500 m / min; the parameters of stretching and shaping are: total stretching multiple is 5~6.2; total relaxation rate is 3~8%, and winding is carried out at a winding speed of 2000~4000 m / min to obtain polyester industrial filament prepared from bottle recycled polyester chips.

[0073] The polyester industrial filaments prepared from the recycled polyester chips from the bottles have a fineness of 100-1110 dtex;

[0074] The breaking strength of the polyester industrial filament prepared from the recycled polyester chips from the bottle is greater than or equal to 6.5 cN / dtex;

[0075] The coefficient of variation of the breaking strength of the polyester industrial filament prepared from the recycled polyester chips from the bottle is less than or equal to 4.0%;

[0076] The breaking elongation of the polyester industrial filament prepared from the recycled polyester chips from the bottle is 13-19%;

[0077] When it is used to prepare a regenerative airbag, the specific steps are:

[0078] Step 1, placing bottle recycled polyester chips with viscosity (0.65-0.8 dl / g) and filtration value (0-5 MPa) in an intermittent drum reactor, rotating it under a vacuum of 10-15 pa, and then heating the temperature in the reactor to 150-180° C. and heating it for 2-12 hours by heating the heat transfer oil pipe to obtain pre-crystallized chips, and then continuing to heat the temperature in the reactor to 210-220° C. by heating the heat transfer oil pipe, and continue heating for 25-40 hours, so that the viscosity of the bottle recycled chips is increased from 0.65-0.8 dl / g to 1.1-1.2 dl / g after solid phase polymerization, and high viscosity chips are formed.

[0079] Step 2, conveying the high-viscosity slices after solid phase polymerization to a screw extruder, and then extruding the melt through the screw extruder, wherein the screw diameter of the screw extruder is 75-170 mm, the screw aspect ratio is 24-33, the screw outlet temperature is ≥280°C, the length ratio of the feed section, the melting section, and the metering section in the screw extruder is 1: (1.0-3.0): (1.0-4.0), the feed section temperature is 290-305°C, the melting section temperature is 300-315°C, and the metering section temperature is 280-290°C.

[0080] Step 3: The extruded melt is distributed to the melt pipes of each spinning box through the melt main pipe to form a spinning melt. The spinning melt enters the spinning assembly through a metering pump and is filtered through the filter in the spinning assembly. The melt is ejected from the spinneret to obtain a melt stream. The number of spinneret holes in the spinneret is 72 to 300; the ratio of the microporous channel length of the spinneret hole to the diameter of the spinneret hole is 1.0 to 3.0; the filter screen accuracy of the filter in the spinning assembly is 5 to 30 μm to improve the uniformity of the filament body. A biphenyl temperature of 295 to 305°C is used to maintain good melt fluidity and pressure.

[0081] Step 4: After each group of melt streams are subjected to slow cooling treatment, the melt streams are cooled by side blowing to obtain the wire body. The side blowing temperature is 18-25°C, the wind speed is 0.4-0.6m / s, and the humidity is 50-70%. During the slow cooling treatment, a heating hood with a temperature of 300-350°C and a heat insulation cylinder with a height of 200-400mm are used.

[0082] Step 5, after the cooled filament body enters the spinning tunnel, it is stretched, shaped and wound to obtain polyester industrial filament prepared from bottle recycled polyester chips. Specifically, oil is applied on the surface of the filament body, and then stretched, shaped and wound; wherein the stretching and shaping are completed by 6 pairs of rollers; the first pair of rollers: the temperature is 80-95°C, the speed is 300-600 m / min, the second pair of rollers: the temperature is 100-135°C, the speed is 300-600 m / min, the third pair of rollers: the temperature is 100-135°C, the speed is 1400-1 600 m / min, the fourth pair of rollers: temperature of 230-255°C, speed of 2500-2700 m / min, the fifth pair of rollers: temperature of 230-255°C, speed of 2400-2600 m / min, the sixth pair of rollers: no heating, speed of 2000-2600 m / min; the parameters of stretching and shaping are: total stretching multiple of 5-6.2; total relaxation rate of 7-9%, and winding molding is carried out under the condition of a winding speed of 2000-4000 m / min to obtain polyester industrial filaments prepared from bottle recycled polyester chips.

[0083] The polyester industrial filament prepared from the bottle recycled polyester chips has a fineness of 350 to 2220 dtex;

[0084] The breaking strength of the polyester industrial filament prepared from the recycled polyester chips from the bottle is greater than or equal to 7.3 cN / dtex;

[0085] The coefficient of variation of the breaking strength of the polyester industrial filament prepared from the recycled polyester chips from the bottle is less than or equal to 3.0%;

[0086] The breaking elongation of the polyester industrial filament prepared from the bottle recycled polyester chips is 18-24%;

[0087] When it is used to prepare a recycled safety belt, the specific steps are:

[0088] Step 1, placing bottle recycled polyester chips with a viscosity (0.65-0.8 dl / g) and a filtration value (0-5 MPa) in an intermittent drum reactor, rotating it under a vacuum of 10-15 pa, and then heating the temperature in the reactor to 150-180° C. and heating it for 2-12 hours by heating the heat transfer oil pipe to obtain pre-crystallized chips, and then continuing to heat the temperature in the reactor to 180-220° C. by heating the heat transfer oil pipe, and continue heating for 20-35 hours, so that the viscosity of the bottle recycled chips is increased from 0.65-0.8 dl / g to 1.1-1.2 dl / g after solid phase polymerization, and high viscosity chips are formed.

[0089] Step 2, conveying the high-viscosity slices after solid phase polymerization to a screw extruder, and then extruding the melt through the screw extruder, wherein the screw diameter of the screw extruder is 75-170 mm, the screw aspect ratio is 24-33, the screw outlet temperature is ≥280°C, the length ratio of the feed section, the melting section, and the metering section in the screw extruder is 1: (1.0-3.0): (1.0-4.0), the feed section temperature is 295-305°C, the melting section temperature is 300-320°C, and the metering section temperature is 285-300°C.

[0090] Step 3: The extruded melt is distributed to the melt pipes of each spinning box through the melt main pipe to form a spinning melt. The spinning melt enters the spinning assembly through a metering pump and is filtered through the filter screen in the spinning assembly. The melt is ejected from the spinneret to obtain a melt stream. The number of spinneret holes in the spinneret is 72-192; the ratio of the microporous channel length of the spinneret hole to the diameter of the spinneret hole is 1.0-3.0; the filter screen accuracy of the filter screen in the spinning assembly is 5-30μm to improve the uniformity of the filament body. A biphenyl temperature of 295-305°C is used to maintain good melt fluidity and pressure.

[0091] Step 4: After each group of melt streams are subjected to slow cooling treatment, the melt streams are cooled by side blowing to obtain the wire body. The side blowing temperature is 18-25°C, the wind speed is 0.4-0.6m / s, and the humidity is 50-70%. During the slow cooling treatment, a heating hood with a temperature of 300-350°C and a heat insulation cylinder with a height of 300-500mm are used.

[0092] Step 5, after the cooled filament body enters the spinning tunnel, it is stretched, shaped and wound to obtain polyester industrial filament prepared from bottle recycled polyester chips. Specifically, oil is applied on the surface of the filament body, and then stretched, shaped and wound; wherein the stretching and shaping is completed by 5 pairs of rollers; the first pair of rollers: the temperature is 85-100°C, the speed is 300-500 m / min, the second pair of rollers: the temperature is 110-140°C, the speed is 300-500 m / min, the third pair of rollers: the temperature is 1 00~140℃, speed is 1200~1500m / min, the fourth pair of rollers: temperature is 220~250℃, speed is 2300~2600m / min, the fifth pair of rollers: no heating, speed is 2300~4000m / min; the parameters of stretching and shaping are: total stretching multiple is 5~6.5; total relaxation rate is 1~5%, and winding is carried out at a winding speed of 2000~4000m / min to obtain polyester industrial filament prepared from bottle recycled polyester chips.

[0093] The polyester industrial filaments prepared from the recycled polyester chips from the bottles have a fineness of 555-2220 dtex;

[0094] The breaking strength of the polyester industrial filament prepared from the recycled polyester chips from the bottle is greater than or equal to 7.3 cN / dtex;

[0095] The coefficient of variation of the breaking strength of the polyester industrial filament prepared from the recycled polyester chips from the bottle is less than or equal to 3.0%;

[0096] The breaking elongation of the polyester industrial filament prepared from the bottle recycled polyester chips is 12-18%;

[0097] The intermediate elongation of the polyester industrial filament prepared from the bottle recycled polyester chips is 5-7%.

[0098] Example 1

[0099] Preparation of polyester industrial filament used in recycled tire cord fabric (recycled tire cord fabric yarn, which is a high modulus low shrinkage yarn):

[0100] Step 1, placing bottle recycled PET polyester chips with an average viscosity of 0.75 dl / g and a filtration value (0-5 MPa) in an intermittent drum reactor, rotating it under a vacuum condition of 10 Pa, and then uniformly raising the temperature in the reactor to 160° C. and heating it for 11 hours by heating the heat transfer oil pipe to obtain pre-crystallized chips, and then continuing to uniformly raise the temperature in the reactor to 217° C. by heating the heat transfer oil pipe, and continue heating for 31-32 hours, so that the viscosity of the bottle recycled chips is increased from 0.75 dl / g to 1.149 dl / g after solid phase polymerization, and high viscosity chips are formed.

[0101] Step 2: convey the high-viscosity slices after solid phase polymerization to a screw extruder, and then extrude the melt through the screw extruder, wherein the screw diameter of the screw extruder is 130 mm, and the length and temperature of the feed section, the length and temperature of the melting section, the length and temperature of the metering section, and the screw outlet temperature are shown in Table 1.

[0102] Step 3, the extruded melt is distributed to the melt pipes of each spinning box through the melt main pipe to form a spinning melt. The spinning melt enters the spinning assembly through a metering pump and is filtered through the filter screen in the spinning assembly. The melt is ejected from the spinneret to obtain a melt stream. The number of spinneret holes in the spinneret is shown in Table 2; the ratio of the microporous channel length of the spinneret hole to the diameter of the spinneret hole is 1.3, and the microporous channel length refers to the length of the spinneret hole corresponding to the forward direction of the melt; the maximum accuracy of the filter screen in the spinning assembly is 25μm (referring to the maximum accuracy in the four-layer metal filter screen) to improve the uniformity of the filament body. A biphenyl temperature of 298°C is used to maintain good melt fluidity and pressure.

[0103] Step 4: After each group of melt streams are subjected to slow cooling treatment, the melt streams are cooled by annular blowing to obtain the filament body. The annular blowing temperature is 60°C, the dynamic pressure is 0.03kPa, and the humidity is 60%. The temperature of the heating cover in the slow cooling device is 330°C, and the height of the insulation cylinder is 80mm, so as to improve the phenomenon of large CV value of physical properties and many broken filaments caused by uneven cooling.

[0104] Step 5, after the cooled silk strip body enters the spinning tunnel, it is stretched, shaped and wound to obtain polyester industrial filaments prepared from recycled polyester chips from bottles. Specifically, oil is applied on the surface of the silk strip body, and then it is stretched, shaped and wound; wherein the stretching and shaping are completed by 6 pairs of rollers; the first pair of rollers: the temperature is 92°C and the speed is 2853 m / min, the second pair of rollers: the temperature is 97°C and the speed is 4020 m / min, the third, fourth and fifth pairs of rollers: the temperature is 258°C and the speed is 5820 m / min, the sixth pair of rollers: no heating, the speed is 5600 m / min; the parameters of stretching and shaping are: the total stretching multiple is 2.04; the total relaxation rate is 3.78%, and the winding is carried out at a winding speed of 5600 m / min to obtain polyester industrial filaments prepared from recycled polyester chips from bottles.

[0105] Example 2

[0106] Preparation of polyester industrial filament (regenerated sewing thread) used in recycled sewing thread:

[0107] Step 1, placing bottle recycled PET polyester chips with an average viscosity of 0.75 dl / g and a filtration value (0-5 MPa) in an intermittent drum reactor, rotating it under a vacuum of 15 pa, and then uniformly raising the temperature in the reactor to 160°C by heating the heat transfer oil pipe and heating it for 11 hours to obtain pre-crystallized chips, and then continuing to uniformly raise the temperature in the reactor to 215°C by heating the heat transfer oil pipe, and continue heating for 29 hours, so that the viscosity of the bottle recycled chips is increased from 0.75 dl / g to 1.121 dl / g after solid phase polymerization, and high viscosity chips are formed.

[0108] Step 2: convey the high-viscosity slices after solid phase polymerization to a screw extruder, and then extrude the melt through the screw extruder, wherein the screw diameter of the screw extruder is 125 mm, and the length and temperature of the feed section, the length and temperature of the melting section, the length and temperature of the metering section, and the screw outlet temperature are shown in Table 1.

[0109] Step 3: The extruded melt is distributed to the melt pipes of each spinning box through the melt main pipe to form a spinning melt. The spinning melt enters the spinning assembly through a metering pump and is filtered through the filter screen in the spinning assembly. The melt is ejected from the spinneret to obtain a melt stream. The number of spinneret holes in the spinneret is shown in Table 2; the ratio of the microporous channel length of the spinneret hole to the diameter of the spinneret hole is 2.0, and the microporous channel length refers to the length of the spinneret hole corresponding to the forward direction of the melt; the maximum accuracy of the filter screen in the spinning assembly is 20μm to improve the uniformity of the filament body. A biphenyl temperature of 296°C is used to maintain good melt fluidity and pressure.

[0110] Step 4: After each group of melt streams are subjected to slow cooling treatment, the melt streams are cooled by side blowing to obtain the filament body. The side blowing temperature is 25°C, the wind speed is 0.5m / s, and the humidity is 60%. The temperature of the heating cover in the slow cooling device is 330°C, and the height of the insulation cylinder is 150mm, so as to improve the phenomenon of large CV value of physical properties and many broken ends and hairy filaments caused by uneven cooling.

[0111] Step 5, after the cooled silk strip body enters the spinning tunnel, it is stretched, shaped and wound to obtain polyester industrial filaments prepared from recycled polyester chips from bottles. Specifically, oil is applied on the surface of the silk strip body, and then it is stretched, shaped and wound; wherein the stretching and shaping are completed by 5 pairs of rollers; the first pair of rollers: temperature is 87°C, speed is 446 m / min, the second pair of rollers: temperature is 115°C, speed is 456 m / min, the third pair of rollers: temperature is 115°C, speed is 1476 m / min, the fourth pair of rollers: temperature is 242°C, speed is 2540 m / min, the fifth pair of rollers: no heating, speed is 2409 m / min; wherein the parameters of stretching and shaping are: total stretching multiple is 5.70; total relaxation rate is 5.51%, and winding is carried out at a winding speed of 2400 m / min to obtain polyester industrial filaments prepared from recycled polyester chips from bottles.

[0112] Example 3

[0113] Preparation of polyester industrial filament (regenerated airbag filament) used in recycled airbags:

[0114] Step 1. Place bottle recycled PET polyester chips with an average viscosity of 0.75 dl / g and a filtration value (0-5 MPa) in an intermittent drum reactor, rotate it under a vacuum condition of 10 Pa, and then heat the temperature in the reactor to 160° C. and heat it for 11 hours by heating the heat transfer oil pipe to obtain pre-crystallized chips, and then continue to heat the temperature in the reactor to 217° C. by heating the heat transfer oil pipe, and continue to heat it for 32 hours, so that the viscosity of the bottle recycled chips is increased from 0.75 dl / g to 1.15 dl / g after solid phase polymerization, and high viscosity chips are formed.

[0115] Step 2: convey the high-viscosity slices after solid phase polymerization to a screw extruder, and then extrude the melt through the screw extruder, wherein the screw diameter of the screw extruder is 130 mm, and the length and temperature of the feed section, the length and temperature of the melting section, the length and temperature of the metering section, and the screw outlet temperature are shown in Table 1.

[0116] Step 3: The extruded melt is distributed to the melt pipes of each spinning box through the melt main pipe to form a spinning melt. The spinning melt enters the spinning assembly through a metering pump and is filtered through the filter screen in the spinning assembly. The melt is ejected from the spinneret to obtain a melt stream. The number of spinneret holes in the spinneret is shown in Table 2; the ratio of the microporous channel length of the spinneret hole to the diameter of the spinneret hole is 2.0, and the microporous channel length refers to the length of the spinneret hole corresponding to the forward direction of the melt; the maximum accuracy of the filter screen in the spinning assembly is 20μm to improve the uniformity of the filament body. A biphenyl temperature of 296°C is used to maintain good melt fluidity and pressure.

[0117] Step 4: After each group of melt streams are subjected to slow cooling treatment, the melt streams are cooled by side blowing to obtain the wire body. The side blowing temperature is 25°C, the wind speed is 0.55m / s, and the humidity is 60%. The temperature of the heating cover in the slow cooling device is 330°C, and the height of the insulation cylinder is 250mm, so as to improve the phenomenon of large CV value of physical properties and many broken wires caused by uneven cooling.

[0118] Step 5, after the cooled filament body enters the spinning tunnel, it is stretched, shaped and wound to obtain polyester industrial filament prepared from bottle recycled polyester chips. Specifically, oil is applied on the surface of the filament body, and then stretched, shaped and wound; wherein the stretching and shaping is completed by 6 pairs of rollers; the first pair of rollers: temperature 92 ° C, speed 452 m / min, the second pair of rollers: temperature 120 ° C, speed 462 m / min, the third pair of rollers: temperature 120 ° C, speed 1 492 m / min, the fourth pair of rollers: temperature of 240°C, speed of 2615 m / min, the fifth pair of rollers: temperature of 240°C, speed of 2500 m / min, the sixth pair of rollers: no heating, speed of 2400 m / min; wherein, the parameters for stretching and shaping are: total stretching multiple of 5.79; total relaxation rate of 8.22%, and winding shaping is carried out at a winding speed of 2400 m / min to obtain polyester industrial filaments prepared from bottle recycled polyester chips.

[0119] Example 4

[0120] Preparation of polyester industrial filament (regenerated seat belt yarn) used in recycled seat belts:

[0121] Step 1. Place bottle recycled PET polyester chips with an average viscosity of 0.75 dl / g and a filtration value (0-5 MPa) in an intermittent drum reactor, rotate it under a vacuum of 10 Pa, and then evenly increase the temperature in the reactor to 160° C. and heat it for 11 hours by heating the heat transfer oil pipe to obtain pre-crystallized chips. Then continue to evenly increase the temperature in the reactor to 215° C. by heating the heat transfer oil pipe, and continue to heat it for 30 hours, so that the viscosity of the bottle recycled chips is increased from 0.75 dl / g to 1.13 dl / g after solid phase polymerization, and form high viscosity chips.

[0122] Step 2: convey the high-viscosity slices after solid phase polymerization to a screw extruder, and then extrude the melt through the screw extruder, wherein the screw diameter of the screw extruder is 130 mm, and the length and temperature of the feed section, the length and temperature of the melting section, the length and temperature of the metering section, and the screw outlet temperature are shown in Table 1.

[0123] Step 3: The extruded melt is distributed to the melt pipes of each spinning box through the melt main pipe to form a spinning melt. The spinning melt enters the spinning assembly through a metering pump and is filtered through the filter screen in the spinning assembly. The melt is ejected from the spinneret to obtain a melt stream. The number of spinneret holes in the spinneret is shown in Table 2; the ratio of the microporous channel length of the spinneret hole to the diameter of the spinneret hole is 2.0, and the microporous channel length refers to the length of the spinneret hole corresponding to the forward direction of the melt; the maximum accuracy of the filter screen in the spinning assembly is 25μm to improve the uniformity of the filament body. A biphenyl temperature of 296°C is used to maintain good melt fluidity and pressure.

[0124] Step 4: After each group of melt streams are subjected to slow cooling treatment, the melt streams are cooled by side blowing to obtain the wire body. The side blowing temperature is 25°C, the wind speed is 0.55m / s, and the humidity is 60%. The temperature of the heating cover in the slow cooling device is 310°C, and the height of the insulation cylinder is 450mm, so as to improve the phenomenon of large CV value of physical properties and many broken wires caused by uneven cooling.

[0125] Step 5, after the cooled silk strip body enters the spinning tunnel, it is stretched, shaped and wound to obtain polyester industrial filaments prepared from recycled polyester chips from bottles. Specifically, oil is applied on the surface of the silk strip body, and then it is stretched, shaped and wound; wherein the stretching and shaping are completed by 5 pairs of rollers; the first pair of rollers: the temperature is 94°C, the drawing speed is 408 m / min, the second pair of rollers: the temperature is 123°C, the drawing speed is 416 m / min, the third pair of rollers: the temperature is 123°C, the drawing speed is 1334 m / min, the fourth pair of rollers: the temperature is 230°C, the drawing speed is 2465 m / min, the fifth pair of rollers: no heating, the drawing speed is 2400 m / min; wherein the parameters of the stretching and shaping are: the total stretching multiple is 6.04; the total relaxation rate is 2.64%, and the winding is carried out at a winding speed of 2400 m / min to obtain polyester industrial filaments prepared from recycled polyester chips from bottles.

[0126] Comparative Example 1

[0127] 0.665 dl / g virgin PET chips were used to completely replace the regenerated chips in Examples 1-4, and the virgin chips were used to produce polyester industrial filaments for different products according to the methods of Examples 1-4. The relevant parameters in the steps are shown in Tables 1-4.

[0128] In Examples 1-4 and Comparative Example 1, the filter screen in the spinning assembly adopts a four-layer metal filter screen, which has good high-temperature oxidation resistance, resistance to melt scouring and corrosion, and good structural stability; and the filtering accuracy is reduced layer by layer, which can remove impurities and gel particles that may remain in the regenerated slice melt, prevent clogging of the spinneret holes of the spinning assembly, and establish a stable spinning pressure, which is conducive to evenly distributing the melt to all the spinneret holes on the spinning plate, and making the melt have the same flow path, flow rate and pressure. For example, from top to bottom, the accuracy of the first layer of metal filter screen is 20 or 25μm, the accuracy of the second layer of metal filter screen is 15μm, the accuracy of the third layer of metal filter screen is 10μm, and the accuracy of the fourth layer of metal filter screen is 5μm. The four layers of metal filter screen are pressed into an integrated structure.

[0129] Table 1 Screw extruder related parameters

[0130]

[0131]

[0132] Table 2 Spinning related parameters 1

[0133]

[0134] Table 3 Spinning related parameters II

[0135]

[0136] Table 4 Parameters related to the stretching part

[0137]

[0138]

[0139] The relevant performance parameters of the polyester industrial filaments obtained in Examples 1-4 and Comparative Example 1 are shown in Tables 5 to 7.

[0140] Table 5 Relevant performance parameters of polyester industrial filament

[0141]

[0142]

[0143] In this paper, the fineness, fineness variation coefficient CV, breaking strength, breaking strength, breaking strength variation coefficient CV, breaking elongation, breaking elongation CV, intermediate elongation, and dry heat shrinkage are measured according to GB / T 16604. The oil content is measured according to GB / T6504-NMR. The network degree is measured according to the hook method.

[0144] Table 6 Relevant performance parameters of polyester industrial filament

[0145]

[0146] Table 7 Relevant performance parameters of polyester industrial filament

[0147]

[0148]

[0149] The relevant performance parameters of the original slices used in Comparative Example 1 are shown in Table 8, and the relevant performance parameters of the regenerated slices used in Example 3 are also shown in Table 8.

[0150] Table 8 Comparison of performance of original slices and regenerated slices

[0151]

[0152]

[0153] The L value and B value are determined by Lab color analysis.

[0154] Comparative Example 2

[0155] Recycled chips can be blended and spun with virgin chips in proportion to improve the mechanical properties of the yarn. The higher the content of recycled chips, the lower the strength of the polyester industrial filament.

[0156] The regenerated slices used in Example 3 were mixed with the original slices used in Comparative Example 1, and the mass ratio of the regenerated slices was 30% (the mass ratio of the original slices was 70%) and 50% (the mass ratio of the original slices was 50%), respectively. According to the specific steps in Example 3, polyester industrial filaments prepared by mixed slices with the mass ratio of the regenerated slices being 30% and 50% were prepared. The performance parameter data were tested, and the data of the two were compared with the polyester industrial filaments prepared in Example 3 (i.e., 100% regenerated slices), as shown in Table 9.

[0157] Table 9 Performance parameters of polyester industrial filaments prepared from recycled chips in different proportions

[0158]

[0159] The viscosity of oil-containing threads is measured using GB / T 14190 standard.

[0160] Comparative Example 3

[0161] Compared with Example 4, the only difference is that the four-layer metal filter is replaced by a three-layer filter structure commonly used in original slices (felt mesh in the middle, supported by sieve plates at the top and bottom, and a filtration accuracy of 20 μm).

[0162] Comparative Example 4

[0163] Compared with Example 4, the only difference is that the length ratio of the feeding section, the melting section and the metering section is 1:1:1 and the lengths of the feeding section, the melting section and the metering section are all 864 mm.

[0164] Comparative Example 5

[0165] Compared with Example 4, the only difference is that the regenerated slices with a filtration value of 10 MPa are selected.

[0166] The polyester industrial filaments prepared in Comparative Examples 3-5 were tested, and the results are shown in Table 10. The breakage times and hair amount test data of Comparative Examples 3-5, Example 4, and Example 4 in the process of preparing polyester industrial filaments by replacing 100% virgin chips are shown in Table 11.

[0167] Table 10 Test results of polyester industrial filaments obtained in Comparative Examples 3-5

[0168]

[0169] Table 11 Detection data of the number of broken ends and the amount of hair in comparative examples 3-5 and embodiment 4

[0170]

[0171] In Comparative Example 3, since the filter screen structure used is a felt screen, there are relatively more impurities in the process of preparing polyester industrial filaments from recycled slices, which leads to blockage of the filter structure and rapid pressure increase of the spinning component. As the pressure of the component increases, the efficiency of the metering pump decreases (the fineness decreases), the melt is severely degraded (the strength and elongation decrease), and the hairy fibers and broken ends increase significantly.

[0172] Because recycled bottle flakes contain IPA, high screw temperature will lead to a large amount of degradation. However, when the temperature is low and the length of the metering section is not increased, the melt fluidity is poor, the mixing is uneven, the spinnability deteriorates, and the stretching uniformity is affected. Therefore, the fineness of comparative example 4 decreases, the fineness CV increases, the strength and elongation decrease, the strength CV increases, and the hair and broken ends increase significantly.

[0173] In comparative example 5, since the regenerated slices with high filtration values ​​contain more impurities, the filtration structure will be blocked and the spinning component will be pressurized quickly. As the pressure of the component increases, the efficiency of the metering pump decreases (the fineness decreases), the melt is severely degraded (the strength and elongation decrease), and the hairy fibers and broken ends increase significantly.

[0174] It should be understood that the above embodiments do not limit the present invention in any form, and any technical solutions obtained by equivalent replacement or equivalent transformation shall fall within the protection scope of the present invention.

Claims

1. A method for preparing polyester industrial filament by recycling recycled polyester chips from bottles, characterized in that: The steps include: Step 1, placing bottle recycled polyester chips with a viscosity of 0.65-0.8 dl / g and a filtration value of 0-5 MPa, and a certain amount of original chips in an intermittent solid phase polymerization reactor, and under a vacuum degree of 10-15 Pa, uniformly raising the temperature in the intermittent solid phase polymerization reactor to 150-180° C. and heating for 2-12 hours to obtain pre-crystallized chips; continuing to uniformly raise the temperature in the intermittent solid phase polymerization reactor to 180-220° C. and continue heating for 20-40 hours, so that the viscosity of the bottle recycled polyester chips is increased to 1.0-1.3 dl / g through solid phase polymerization, forming regenerated high-viscosity chips; Step 2, conveying the regenerated high-viscosity slices to a screw extruder, and extruding the melt through the screw extruder, wherein the screw outlet temperature of the screw extruder is ≥280°C; the length ratio of the feed section, the melting section, and the metering section in the screw extruder is 1: (1.0-3.0): (1.0-4.0); Step 3, the melt extruded by the screw extruder is distributed to the spinning manifold to form a spinning melt, and the spinning melt is ejected from the spinneret after filtering at 295-305°C to obtain a melt flow; wherein the filtering accuracy is 5-30 μm; Step 4, slowly cooling the melt flow, and then cooling the melt flow by ring blowing or side blowing to obtain a wire body; Step 5, after the cooled filament body enters the spinning tunnel, it is stretched, shaped and wound to obtain polyester industrial filament prepared from recycled polyester chips, wherein the stretching and shaping parameters are: a pulling speed of 300-4000 m / min; oiling on the surface of the filament body; a total stretching multiple of 1.0-6.5, a shaping temperature of 230°C-260°C; a total relaxation rate of 1.6-9%, and winding is performed at a winding speed of 2000-7000 m / min to obtain polyester industrial filament prepared from recycled polyester chips recycled from bottles.

2. The method for preparing polyester industrial filament by using recycled polyester chips from bottles according to claim 1, characterized in that: The recycled polyester chips from bottles and the virgin chips constitute the overall chips, in which the mass proportion of the recycled polyester chips from bottles in the overall chips is ≥10wt% and ≤100wt%; a certain amount of virgin chips refers to the mass proportion of the virgin chips in the overall chips is ≥0wt% and ≤90wt%.

3. The method for preparing polyester industrial filament by using recycled polyester chips from bottles according to claim 1, characterized in that: In step 4, the slow cooling treatment is completed by a heating hood with a temperature of 300~350℃ and an insulating cylinder with a height of 50~500mm; the ring blowing temperature is 50~70℃, the dynamic pressure is 0.02~0.06kPa, and the humidity is 50~70%; the side blowing temperature is 18~25℃, the wind speed is 0.4~0.6m / s, and the humidity is 50~70%.

4. The method for preparing polyester industrial filament by using recycled polyester chips from bottles according to claim 1, characterized in that: In step 3, a multi-layer metal filter is used, and the filtering accuracy of the multi-layer metal filter decreases layer by layer along the forward direction of the spinning melt, and the spinning melt is evenly distributed to the spinneret holes.

5. The method for preparing polyester industrial filament by using recycled polyester chips from bottles according to claim 1, characterized in that: The polyester industrial filament prepared by using recycled polyester chips from bottles has a fineness of 167-3300 dtex and a breaking strength of ≥6.0 cN / dtex.

6. The method for preparing polyester industrial filament by using recycled polyester chips from bottles according to claim 1, characterized in that: The polyester industrial filament prepared by using recycled polyester chips from bottles has a breaking strength variation coefficient of ≤4.0%.

7. The method for preparing polyester industrial filament by using recycled polyester chips from bottles according to claim 1, characterized in that: In step 3, the ratio of the micropore channel length of the spinneret hole to the diameter of the spinneret hole is 1.0 to 3.

0.

8. The method for preparing polyester industrial filament by using recycled polyester chips from bottles according to claim 1, characterized in that: The polyester industrial filament prepared by using recycled polyester chips from bottles has an elongation at break of 7-33% and an intermediate elongation of 5-20%.

9. Polyester industrial filaments obtained by the method for preparing polyester industrial filaments by using recycled polyester chips from bottles as described in any one of claims 1 to 8.

10. The polyester industrial filament prepared according to claim 9, characterized in that: The polyester industrial filament is used for preparing tire cord fabric, safety belt, air bag or sewing thread.

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