Preparation method of nonlinear polyester high-strength and high-modulus fiber

Abstract

The invention discloses a preparation method of a nonlinear polyester high-strength high-modulus fiber, which comprises the following steps: pretreating a raw material with the intrinsic viscosity of 0.8-1.2 dL / g; the raw material is 100% non-linear polyester chips, and dibasic acid such as IPA or dibasic alcohol such as NPG is contained in the non-linear polyester chips or on a polymer molecular chain. The raw material purity index filtering pressure rise value is less than 5.0 Mpa / kg; s2, the raw materials pretreated in the step S1 are subjected to melt extrusion, spinning and cooling, and the melt draw ratio of a melt in the spinning process is 250-2000; the tows cooled in the step S2 are dragged, shaped and rolled, and the strength gt of the nonlinear polyester high-strength high-modulus fiber is obtained; 7.8 g / d, the dimensional stability index 1t; and 11%. By improving the purity of the raw materials, reducing impurity crystal nucleuses, improving the draftability, selecting slices with intrinsic viscosity in a corresponding range, and through the spinning process design of a special spinneret plate, a melt draw ratio and the like, the problems that non-linear polyester slices are low in crystallization speed, low in crystallinity, poor in crystal region stability and the like, and are not beneficial to spinning traction are solved; and the balance between productivity and good mechanical properties is realized.

Description

Technical Field

[0001] The invention relates to the technical field of machine vision, and in particular to a method for preparing nonlinear polyester high-strength and high-modulus fibers. Background Art

[0002] At present, conventional high-strength polyester fiber molecular chains are all linear structures. The advantage of linear polyester fiber is that the linear molecular chains are easy to be arranged in an orderly and regular manner during the spinning process, so that the fiber has high strength, high modulus, and good dimensional stability, and can be used in the fields of automobile tire cords, industrial fabrics, etc. If non-linear polyester chips are used instead, if the molecular chain contains dibasic acids such as IPA (isophthalic acid) or diols such as NPG (neopentyl glycol), the presence of branched chains inside the fiber will reduce the regularity of the PET molecular chain, reduce the melting point of the copolymer, lower the crystallization temperature, and destroy the morphology and stability of the crystallization area, resulting in lower strength and modulus and poor dimensional stability of the fiber obtained after spinning.

[0003] In addition, if the raw materials contain more trace impurities, such as a small amount of mechanical impurities, annular colloids and degraded carbides in bottle recycled polyester chips, it will also affect the regularity of the forward arrangement of the polyester molecular chain in the spinning process, as well as interfere with the crystallization and the amount of crystallization, which is not conducive to high-speed spinning, resulting in poor spinnability, low fiber strength or poor quality stability.

[0004] According to literature research, if you want to improve fiber properties such as strength and dimensional stability, you can improve the orientation and crystallization of the nascent fiber during the spinning process. Generally, the higher the melt stretching ratio SD / R of the nascent silk fiber (the speed of the pre-stretching roller / the melt ejection speed), the greater the inertia and friction force on the molecular chain, the greater the degree of orientation, the larger the grain size, the greater the stability of the crystallization zone, and the mechanical properties of the fiber, thereby improving the strength and dimensional stability of the fiber. However, the improvement brought by the increase in the melt stretching ratio to the performance is not unlimited. Too high a ratio will cause melt fracture and is also affected by the fiber skin-core structure and micropore formation. Therefore, in order to avoid exceeding the limiting relationship between strength and stretchability, the melt stretching ratio SD / R should be maintained at a certain value.

[0005] At present, there is no development technology and large-scale application of 100% nonlinear polyester high-strength and high-modulus fiber products in the industry. This patent is created to overcome this technical difficulty. Therefore, this application designs a preparation method for nonlinear polyester high-strength and high-modulus fibers, overcomes the influence of nonlinear polyester side chains and impurities on forward crystallization, takes into account high strength, high dimensional stability and manufacturability, realizes high-speed and high-precision manufacturing, and improves product performance, which obviously has practical significance. Summary of the invention

[0006] The purpose of the present invention is to provide a method for preparing linear polyester high-strength and high-modulus fibers to improve product performance and production stability.

[0007] To achieve the above object, the technical solution adopted by the present invention is: a method for preparing nonlinear polyester high-strength and high-modulus fiber, comprising the following steps:

[0008] S1. Pretreating the raw material, wherein the intrinsic viscosity of the raw material is 0.8-1.2 dL / g; the raw material is 100% nonlinear polyester chips, wherein the nonlinear polyester chips or polymer molecular chains contain dibasic acids such as IPA or diols such as NPG, and the raw material purity index filtration pressure rise value is less than 5.0 Mpa / kg;

[0009] S2, melt-extrude, spin and cool the raw material pretreated in step S1, wherein the melt stretch ratio of the melt during spinning is 250 to 2000, more preferably, the melt stretch ratio is ≤1900;

[0010] S3, drawing, shaping, and winding the filament bundle cooled in step S2 to obtain nonlinear polyester high-strength and high-modulus fibers.

[0011] Preferably, in step S1, the intrinsic viscosity of the raw material is 0.9-1.15 dL / g.

[0012] Preferably, the nonlinear polyester chips in S1 include polyester bottle chips, polyester recycled bottles, polyester packaging sheets, polyester textiles or recycled polyester chips produced by processing polyester waste silk.

[0013] Preferably, the content of IPA in the nonlinear polyester chips in step S1 is 0.4% to 2.5%, and more preferably 0.8% to 1.8%. The content of IPA in the nonlinear polyester chips can be controlled by selecting different types of raw material sources or raw material mixing ratios.

[0014] Preferably, the raw material pretreatment method in S1 includes melt filtration and slicing and drying the raw materials, wherein the melt filtration uses a filter screen less than 25 microns to remove impurities, and the moisture content of the granulated slices after drying is less than 50 ppm.

[0015] Preferably, the raw material purity test method in step S1 includes: selecting a woven mesh of ≥1500 mesh or a sintered filter screen of ≤10 microns, and the filtration pressure rise value of the slices after melting through the filter screen of the filter performance instrument is less than 5.0Mpa / kg.

[0016] Preferably, in step S2, the melt extrusion method includes inputting the raw material into a screw extruder for high-temperature melting and extruding it into a spinning assembly, the temperature range of each zone of the screw is 270°C to 330°C, and the temperature setting selected in each zone is adjusted according to the viscosity of the raw material and the spinning conditions; the screw head pressure is 9 to 17 MPa.

[0017] Preferably, in step S2, the cooling method includes side-blowing air cooling and ring-blowing air cooling, the wind speed of side-blowing air cooling is 0.3-1.5 m / s, the wind pressure of ring-blowing air cooling is 200-1000 MPa, and the cooling air temperature is 15-80° C. More preferably, the wind pressure of ring-blowing air cooling is 250-850 MPa, and the temperature of the blowing cooling zone is 15-77° C.

[0018] Preferably, in step S3, the filament bundle is drawn and shaped by a high-temperature hot roller, the preheating temperature of the drawing is room temperature to 100° C., the first roller speed is 2200 to 3500 m / min, the drawing ratio is 1.7 to 2.30, the maximum hot roller speed is 4600 to 6700 m / min; the temperature of the heat setting is 210 to 260° C. Drawing and shaping by a high-temperature hot roller can make the filament bundle completely crystallized, the microstructure tends to be stable, the strength and modulus are stabilized, the thermal shrinkage rate is reduced, and good conditions are provided for subsequent winding and forming.

[0019] Preferably, the nonlinear polyester high-strength and high-modulus fiber prepared in step S3 has a strength of >7.8 g / d, a dimensional stability index of E%+H%<11%, and more preferably, the dimensional stability index can reach E%+H%≤10%.

[0020] Preferably, the nonlinear polyester high-strength and high-modulus fiber prepared in step S3 is twisted and dipped to obtain a product that can be used in the fields of cord frame materials, air spring cord frame materials, industrial canvas, rubber hoses, etc.

[0021] Preferably, the dipping method includes a one-bath dipping method or a two-bath dipping method for polyester tire cord fabrics in the industry, both of which can achieve enhanced adhesion performance with rubber.

[0022] In the above, the 100% nonlinear polyester chips used in this application are recycled polyesters, and some of the polymer molecular chains contain dibasic acids such as isophthalic acid (IPA) or diols such as NPG. Trace impurities that are difficult to remove are easily mixed into the raw material recovery and regeneration granulation process. Trace impurities form crystal nuclei during the spinning process, interfering with the forward arrangement of the molecular chains and the regularity of the crystallization, thereby causing yarn breakage and easy generation of hairiness during high-speed spinning, making it difficult to produce high-strength, high-dimensional stability fibers; IPA or other side chains will also affect the crystal morphology and quantity in the fiber, which is not conducive to the formation of neatly arranged and stable crystal regions, so the dimensional stability is poor.

[0023] In this regard, the present application pre-treats the raw materials before spinning, improves the filtration accuracy of the melt during the regeneration granulation process, and reduces the number of trace impurities; controls the viscosity of the raw materials and improves the crystallization speed of polyester during spinning; through the special design of the spinneret and the design of the melt stretching ratio, the inertia force and friction force on the polymer macromolecular chain are increased, the molecular orientation degree is improved, the grain size and crystallinity are increased, and the adverse effects of IPA and NPG on crystallization can be compensated, the stretchability of nonlinear polyester materials can be improved, and the mechanical properties of the fiber can be improved. The present application evaluates the dimensional stability of nonlinear polyester fibers by the sum of the fixed load elongation E% and the dry heat shrinkage H%.

[0024] Due to the application of the above technical solution, the present invention has the following advantages compared with the prior art:

[0025] 1. The present invention controls the impurity content in the nonlinear polyester chips through raw material pretreatment to reduce the interference of impurities on the molecular chain and crystallization, improves the generation of yarn breakage and hairiness during high-speed spinning, and is beneficial to improving fiber strength and spinnability.

[0026] 2. Select appropriate raw material viscosity, and further improve the stretching tension of the melt refinement process through the design of spinneret and melt stretching ratio, improve crystallinity and grain size stability, and ultimately improve fiber performance; solve the problem of poor material forward and crystallization stability caused by the inability to remove IPA or NPG in nonlinear polyester chips.

[0027] 3. The raw material used in the present invention is 100% non-linear recycled polyester, and no additional virgin polyester chips are needed, which reduces the consumption of natural resources and carbon emissions, and is more environmentally friendly. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] In order to more clearly illustrate the specific implementation methods of the present invention or the technical solutions in the prior art, the drawings required for use in the specific implementation methods or the description of the prior art will be briefly introduced below. Obviously, some of the drawings described below are some implementation methods of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0029] Figure 1 This is a preparation flow chart in Example 1 of the present invention. DETAILED DESCRIPTION

[0030] The technical solution of the present invention will be described clearly and completely below. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of them. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0031] A method for preparing a nonlinear polyester high-strength and high-modulus fiber comprises the following steps:

[0032] S1. Pre-treating the raw material, wherein the intrinsic viscosity of the raw material is 0.8-1.2 dL / g; the raw material is 100% non-linear polyester chips, wherein the non-linear polyester chips contain IPA, and the filtration pressure rise value of the raw material purity index is <5 Mpa / kg;

[0033] S2. Melt-extrude, spin and cool the raw materials pretreated in step S1, wherein the melt drawing ratio of the melt-spun filaments during the spinning process is 250 to 2000.

[0034] S3, drawing, shaping, and winding the filament bundle cooled in step S2 to obtain nonlinear polyester high-strength and high-modulus fibers.

[0035] Furthermore, in step S1, the intrinsic viscosity of the raw material is preferably 0.9 to 1.15 dL / g.

[0036] Furthermore, the nonlinear polyester chips in S1 include chips for polyester bottles, polyester recycled bottles, polyester packaging sheets, polyester textiles or recycled polyester chips produced by processing polyester waste silk, etc.

[0037] Furthermore, the content of IPA in the nonlinear polyester chips in step S1 is 0.4% to 2.5%. The content of IPA in the nonlinear polyester chips can be controlled by selecting different types of raw material sources or raw material mixing ratios.

[0038] Furthermore, the content of IPA in the nonlinear polyester slice in step S1 is 0.8% to 1.8%.

[0039] Furthermore, the raw material pretreatment method in S1 includes melt filtration of the raw material and drying of polyester chips, wherein the melt filtration uses a filter screen less than 25 microns to remove impurities, and the moisture content of the pelletized chips after drying is less than 50 ppm.

[0040] Furthermore, the method for testing the purity of raw materials in step S1 includes: using a filtration performance instrument, selecting a filter screen larger than 2000 meshes, and testing that the filtration pressure rise of the raw materials is less than 5Mpa / kg.

[0041] Furthermore, in step S2, the melt extrusion method includes inputting the raw material into a screw extruder for high-temperature melt extrusion, and inputting the spinning assembly, the temperature range of each zone of the screw is 270°C to 330°C, and the temperature setting selected in each zone is adjusted according to the viscosity of the raw material and the spinning conditions; the screw head pressure is 11 to 16 MPa.

[0042] Furthermore, in step S2, the cooling method includes side-blowing air cooling and ring-blowing air cooling, the wind speed of the side-blowing air cooling is 0.3-1.5 m / s, the wind pressure of the ring-blowing air cooling is 250-850 MPa, and the cooling air temperature is 15-77°C.

[0043] Preferably, in step S3, the filament bundle is drawn and shaped by a high-temperature hot roller, the preheating temperature of the drawing is room temperature to 100°C, the first roller speed is 2200 to 3500 m / min, the drawing ratio is 1.7 to 2.30, the maximum hot roller speed is 4600 to 6700 m / min; the temperature of the heat setting is 210 to 260°C.

[0044] Furthermore, the nonlinear polyester high-strength and high-modulus fiber prepared in step S3 is twisted and dipped to obtain a product that can be used in the fields of cord frame materials, air spring cord frame materials, industrial canvas, hoses, etc.

[0045] The dipping method includes a one-bath dipping method or a two-bath dipping method for polyester tire cord fabrics in the industry, both of which can achieve enhanced bonding performance with rubber.

[0046] The technical solution of the present invention will be clearly and completely described below in conjunction with specific embodiments. Obviously, the described embodiments are part of the embodiments of the present invention, rather than all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0047] Example 1

[0048] In this embodiment, nonlinear polyester chips made from recycled polyester bottle flakes are used as raw materials to produce 1000D polyester high-strength high-modulus fiber. The 1000D nonlinear polyester fiber produced in this embodiment is used for tire cord fabric. In this embodiment, the intrinsic viscosity of the raw material is 1.15dL / g, the IPA content is 1.6%; the raw material purity filtration pressure rise value is 3.0Mpa / kg.

[0049] Preparation process: PET chip pretreatment → spinning → twisting → weaving → dipping and heat treatment.

[0050] The moisture content of the slices spun in this embodiment was tested to be 12ppm, the melt drawing ratio of the melt during the spinning process was 800, the spinning temperature of this embodiment was 290°C, the cooling air temperature was 27°C, and the air pressure was 350-400Mpa; the draft ratio was 2.0, the maximum hot roller speed was 5800m / min, and the heat setting temperature was 225°C; the dipping method was a two-bath dipping method, the first bath of the dipping liquid was the D417 formula, and the second bath was conventional RFL dipping.

[0051] Example 2

[0052] In this embodiment, nonlinear polyester chips made from recycled polyester bottle flakes are used as raw materials to produce 1000D polyester high-strength high-modulus fiber. The 1000D nonlinear polyester fiber produced in this embodiment is used for tire cord fabric. In this embodiment, the intrinsic viscosity of the raw material is 0.95dL / g, the content of IPA in the nonlinear polyester chips is 1.15%; the raw material purity filtration pressure rise value is 2.8Mpa / kg.

[0053] Preparation process: PET chip pretreatment → spinning → twisting → weaving → dipping and heat treatment.

[0054] The moisture content of the slices spun in this embodiment was tested to be 10ppm, the melt drawing ratio of the melt during the spinning process was 652, the spinning temperature of this embodiment was 300°C, the cooling air temperature was 61°C, and the air pressure was 350-400Mpa; the draft ratio was 2.15, the maximum hot roller speed was 5800m / min, and the heat setting temperature was 248°C; the dipping method was a two-bath dipping method, the first bath of the dipping liquid was the D417 formula, and the second bath was conventional RFL dipping.

[0055] Example 3

[0056] In this embodiment, nonlinear polyester chips made from recycled polyester bottle flakes are used as raw materials to produce 1000D polyester high-strength high-modulus fiber. The 1000D nonlinear polyester fiber produced in this embodiment is used for tire cord fabric. In this embodiment, the intrinsic viscosity of the raw material is 1.1dL / g, the content of IPA in the nonlinear polyester chips is 1.45%; the raw material purity filtration pressure rise value is 3.1Mpa / kg.

[0057] Preparation process: PET chip pretreatment → spinning → twisting → weaving → dipping and heat treatment.

[0058] The moisture content of the slices spun in this embodiment was tested to be 10ppm, the melt drawing ratio of the melt during the spinning process was 791, the spinning temperature of this embodiment was 305°C, the cooling air temperature was 67°C, and the air pressure was 350-400Mpa; the draft ratio was 2.01, the maximum hot roller speed was 5750m / min, and the heat setting temperature was 255°C; the dipping method was a two-bath dipping method, the first bath of the dipping liquid was the D417 formula, and the second bath was conventional RFL dipping.

[0059] Example 4

[0060] In this embodiment, nonlinear polyester chips made from recycled polyester bottle flakes are used as raw materials to produce 1000D polyester high-strength high-modulus fiber. The 1000D nonlinear polyester fiber produced in this embodiment is used for tire cord fabric. In this embodiment, the intrinsic viscosity of the raw material is 1.04dL / g, the content of IPA in the nonlinear polyester chips is 1.8%; the raw material purity filtration pressure rise value is 3.0Mpa / kg.

[0061] Preparation process: PET chip pretreatment → spinning → twisting → weaving → dipping and heat treatment.

[0062] The moisture content of the slices spun in this embodiment was tested to be 14ppm, the melt drawing ratio of the melt during the spinning process was 760, the spinning temperature of this embodiment was 303°C, the cooling air temperature was 58°C, and the air pressure was 350-400Mpa; the draft ratio was 2.08, the maximum hot roller speed was 5850m / min, and the heat setting temperature was 233°C; the dipping method was a two-bath dipping method, the first bath of the dipping liquid was the D417 formula, and the second bath was conventional RFL dipping.

[0063] Example 5

[0064] In this embodiment, nonlinear polyester chips made from recycled polyester bottle flakes are used as raw materials to produce 1000D polyester high-strength high-modulus fiber. The 1000D nonlinear polyester fiber produced in this embodiment is used for tire cord fabric. In this embodiment, the intrinsic viscosity of the raw material is 1.00 dL / g, the content of IPA in the nonlinear polyester chips is 0.8%; the raw material purity filtration pressure rise value is 3.0 Mpa / kg.

[0065] Preparation process: PET chip pretreatment → spinning → twisting → weaving → dipping and heat treatment.

[0066] The moisture content of the slices spun in this embodiment was tested to be 10ppm, the melt drawing ratio of the melt during the spinning process was 840, the spinning temperature of this embodiment was 288°C, the cooling air temperature was 35°C, and the air pressure was 350-400Mpa; the draft ratio was 1.95, the maximum hot roller speed was 5800m / min, and the heat setting temperature was 255°C; the dipping method was a two-bath dipping method, the first bath of the dipping liquid was the D417 formula, and the second bath was conventional RFL dipping.

[0067] Example 6

[0068] In this embodiment, nonlinear polyester chips made from recycled polyester bottle flakes are used as raw materials to produce 1000D polyester high-strength high-modulus fiber. The 1000D nonlinear polyester fiber produced in this embodiment is used for tire cord fabric. In this embodiment, the intrinsic viscosity of the raw material is 1.07dL / g, the content of IPA in the nonlinear polyester chips is 1.30%; the raw material purity filtration pressure rise value is 5.0Mpa / kg.

[0069] Preparation process: PET chip pretreatment → spinning → twisting → weaving → dipping and heat treatment.

[0070] The moisture content of the slices spun in this embodiment was tested to be 10ppm, the melt drawing ratio of the melt during the spinning process was 781, the spinning temperature of this embodiment was 297°C, the cooling air temperature was 60°C, and the air pressure was 350-400Mpa; the draft ratio was 2.05, the maximum hot roller speed was 5700m / min, and the heat setting temperature was 242°C; the dipping method was a two-bath dipping method, the first bath of the dipping liquid was the D417 formula, and the second bath was conventional RFL dipping.

[0071] Example 7

[0072] In this embodiment, nonlinear polyester chips made from recycled polyester bottle flakes are used as raw materials to produce 1000D polyester high-strength high-modulus fiber. The 1000D nonlinear polyester fiber produced in this embodiment is used for tire cord fabric. The intrinsic viscosity of the raw material is 1.02dL / g, and the content of IPA in the nonlinear polyester chips is 1.23%; the raw material purity filtration pressure rise value is 3.3Mpa / kg.

[0073] Preparation process: PET chip pretreatment → spinning → twisting → weaving → dipping and heat treatment.

[0074] The moisture content of the slices spun in this embodiment was tested to be 11ppm, the melt drawing ratio of the melt during the spinning process was 350, the spinning temperature of this embodiment was 296°C, the cooling air temperature was 47°C, and the air pressure was 350-400Mpa; the draft ratio was 2.05, the maximum hot roller speed was 5850m / min, and the heat setting temperature was 239°C; the dipping method was a two-bath dipping method, the first bath of the dipping liquid was the D417 formula, and the second bath was conventional RFL dipping.

[0075] Example 8

[0076] In this embodiment, nonlinear polyester chips made from recycled polyester bottle flakes are used as raw materials to produce 1000D polyester high-strength high-modulus fiber. The 1000D nonlinear polyester fiber produced in this embodiment is used for tire cord fabric. In this embodiment, the intrinsic viscosity of the raw material is 1.05dL / g, the content of IPA in the nonlinear polyester chips is 1.33%; the raw material purity filtration pressure rise value is 2.5Mpa / kg.

[0077] Preparation process: PET chip pretreatment → spinning → twisting → weaving → dipping and heat treatment.

[0078] The moisture content test result of the spun slices in this embodiment is 10ppm, the melt stretching ratio of the melt during the spinning process is 1410, the spinning temperature of this embodiment is 301°C, the cooling air temperature is 61°C, and the air pressure is 350-400Mpa; the draft ratio is 1.93, the maximum hot roller speed is 5800m / min, and the heat setting temperature is 235°C; the dipping method is a two-bath dipping method, the first bath of the dipping liquid is D417 formula, and the second bath is conventional RFL dipping.

[0079] Example 9

[0080] In this embodiment, nonlinear polyester chips made from recycled polyester bottle flakes are used as raw materials to produce 1000D polyester high-strength high-modulus fiber. The 1000D nonlinear polyester fiber produced in this embodiment is used for tire cord fabric. In this embodiment, the intrinsic viscosity of the raw material is 1.058dL / g, the content of IPA in the nonlinear polyester chips is 1.48%; the raw material purity filtration pressure rise value is 3.5Mpa / kg.

[0081] Preparation process: PET chip pretreatment → spinning → twisting → weaving → dipping and heat treatment.

[0082] The moisture content test result of the spun slices in this embodiment is 8ppm, the melt stretching ratio of the melt during the spinning process is 1900, the spinning temperature of this embodiment is 300°C, the cooling air temperature is 65°C, and the air pressure is 350-400Mpa; the draft ratio is 1.90, the maximum hot roller speed is 5800m / min, and the heat setting temperature is 235°C; the dipping method is a two-bath dipping method, the first bath of the dipping liquid is D417 formula, and the second bath is conventional RFL dipping.

[0083] Comparative Example 1

[0084] In this embodiment, nonlinear polyester chips made from recycled polyester bottle flakes are used as raw materials to produce 1000D polyester high-strength high-modulus fiber. The 1000D nonlinear polyester fiber produced in this embodiment is used for tire cord fabric. In this embodiment, the intrinsic viscosity of the raw material is 1.055dL / g, the content of IPA in the nonlinear polyester chips is 1.55%; the raw material purity filtration pressure rise value is 6.0Mpa / kg.

[0085] Preparation process: PET chip pretreatment → spinning → twisting → weaving → dipping and heat treatment.

[0086] The moisture content of the slices spun in this embodiment was tested to be 13ppm, the melt drawing ratio of the melt during the spinning process was 798, the spinning temperature of this embodiment was 300°C, the cooling air temperature was 65°C, and the air pressure was 350-400Mpa; the draft ratio was 2.05, the maximum hot roller speed was 5800m / min, and the heat setting temperature was 235°C; the dipping method was a two-bath dipping method, the first bath of the dipping liquid was the D417 formula, and the second bath was conventional RFL dipping.

[0087] Comparative Example 2

[0088] In this embodiment, nonlinear polyester chips made from recycled polyester bottle flakes are used as raw materials to produce 1000D polyester high-strength high-modulus fiber. The 1000D nonlinear polyester fiber produced in this embodiment is used for tire cord fabric. In this embodiment, the intrinsic viscosity of the raw material is 1.048dL / g, the content of IPA in the nonlinear polyester chips is 1.31%; the raw material purity filtration pressure rise value is 3.0Mpa / kg.

[0089] Preparation process: PET chip pretreatment → spinning → twisting → weaving → dipping and heat treatment.

[0090] The moisture content of the slices spun in this embodiment was tested to be 8ppm, the melt drawing ratio of the melt during the spinning process was 240, the spinning temperature of this embodiment was 300°C, the cooling air temperature was 65°C, and the air pressure was 350-400Mpa; the draft ratio was 2.16, the maximum hot roller speed was 5850m / min, and the heat setting temperature was 235°C; the dipping method was a two-bath dipping method, the first bath of the dipping liquid was the D417 formula, and the second bath was conventional RFL dipping.

[0091] Comparative Example 3

[0092] In this embodiment, nonlinear polyester chips made from recycled polyester bottle flakes are used as raw materials to produce 1000D polyester high-strength high-modulus fiber. The 1000D nonlinear polyester fiber produced in this embodiment is used for tire cord fabric. In this embodiment, the intrinsic viscosity of the raw material is 1.05dL / g, the content of IPA in the nonlinear polyester chips is 1.45%; the raw material purity filtration pressure rise value is 3.0Mpa / kg.

[0093] Preparation process: PET chip pretreatment → spinning → twisting → weaving → dipping and heat treatment.

[0094] The moisture content of the slices spun in this embodiment was tested to be 9ppm, the melt drawing ratio of the melt during the spinning process was 2283, the spinning temperature in this embodiment was 300°C, the cooling air temperature was 65°C, and the air pressure was 350-400Mpa; the draft ratio was 1.86, the maximum hot roller speed was 5600m / min, and the heat setting temperature was 235°C; the dipping method was a two-bath dipping method, the first bath of the dipping liquid was the D417 formula, and the second bath was conventional RFL dipping.

[0095] The raw material parameters and preparation process parameters used in Examples 1 to 9 are shown in Table 1 below, and the raw material parameters and preparation process parameters used in Comparative Examples 1 to 3 are shown in Table 2 below.

[0096] Table 1

[0097]

[0098] Table 2

[0099] Comparative Example 1 2 3 raw material Bottle recycled polyester Bottle recycled polyester Bottle recycled polyester IPA Content 1.55 1.31 1.45 Intrinsic viscosity 1.055 1.048 1.05 Filtration boost MPa / kg 6Mpa 3Mpa 3Mpa Spinneret stretch ratio 798 240 2283 Draft ratio 2.05 2.16 1.86 Maximum roller speed 5700 5850 5600 Heat setting temperature 235 235 235

[0100] The high-strength and high-modulus fibers and cords produced in Examples 1 to 9 and Comparative Examples 1 to 3 were tested. The physical property test results of Examples 1 to 9 are shown in Table 3 below; the physical property test results of Comparative Examples 1 to 3 are shown in Table 4 below.

[0101] Table 3

[0102]

[0103] Table 4

[0104]

[0105] In the above, in Examples 1 to 9 and Comparative Examples 1 to 3, the raw silk testing method is:

[0106] (1) Strength and elongation test

[0107] The strength and elongation test method of nonlinear polyester fiber is in accordance with the standard ASTM D885, with a tensile speed of 300mm / min, a clamp distance of 250mm, a pre-tension of 0.05cN / dt ex, and a twisting condition of 60T / m. The strength, tenacity, elongation at break and 4.5g / d elongation at constant load (EASL) of the cord fabric warp yarn are measured using a Text echno tensile tester.

[0108] (2) Dry heat shrinkage

[0109] Heat shrinkage instrument: 177°C, heat treatment time 10 minutes. Pre-tension 0.05 cN / dt ex.

[0110] (3) Linear density D

[0111] Denier——nominal fineness (1000DX2 is 2000D), D.

[0112] (4) Dimensional stability

[0113] In the above text, dry heat shrinkage + fixed elongation load = E + H = dimensional stability index. Generally, the smaller the E + H index, the better the dimensional stability;

[0114] In the above, in Examples 1 to 9 and Comparative Examples 1 to 3, the dipping line test method is:

[0115] (1) Strength and elongation test

[0116] According to GB / T 19390, stretching speed: 300mm / min, clamp distance 250mm; pre-tension

[0117] 0.05cN / dt ex, using a tensile tester to measure the strength, tenacity, elongation at break and elongation at fixed load (EASL) of the cord fabric warp yarn.

[0118] (2) Dry heat shrinkage

[0119] Oven method: 177°C, heat treatment time 2 minutes, pre-tension 0.05 cN / dt ex.

[0120] (3) Dimensional stability

[0121] Dry heat shrinkage + fixed elongation load = E + H = dimensional stability index. Generally, the smaller the E + H index, the better the dimensional stability;

[0122] By comparing the above embodiments, it can be clearly seen that after the non-linear polyester chips are controlled by controlling the filtration pressure rise, the melt stretching ratio is set within 250-2000, and the dimensional stability index E%+H% of the produced non-linear polyester high-strength yarn is <11%, especially when the melt stretching ratio is higher, such as when the melt stretching ratio is >650 in this embodiment, the dimensional stability index is ≤10%, and the polyester fiber with high dimensional stability is obtained. The dimensional stability index of the dipped line is ≤6.8%, which meets the requirements of tire cord fabric.

[0123] By comparing the comparative example with the embodiment, it can be clearly seen that if the raw material filtration pressure rise value is greater than 5Mpa / kg, it will affect the dimensional stability and spinnability of the precursor, and the yarn will be easily broken. The dimensional stability index after dipping is >6.8%, and the product is unqualified. If the melt stretch ratio is lower than 250, the E+H of the produced precursor is too high and the dimensional stability is poor; if the melt stretch ratio is too high, the stress after the melt is cooled will be too high, resulting in yarn breakage and poor spinnability.

[0124] The above description of the disclosed embodiments enables one skilled in the art to implement or use the present invention. Various modifications to these embodiments will be apparent to one skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the present invention. Therefore, the present invention will not be limited to the embodiments shown herein, but rather to the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A method for preparing nonlinear polyester high-strength and high-modulus fiber, characterized in that: The following steps are involved: S1. Pretreating the raw material, wherein the intrinsic viscosity of the raw material is 0.8-1.2 dL / g; The raw material is 100% nonlinear polyester chips, wherein the nonlinear polyester chips or polymer molecular chains contain dibasic acids such as IPA or diols such as NPG, and the raw material purity index filtration pressure rise value is less than 5.0Mpa / kg; S2, melt-extrude, spin and cool the raw materials pretreated in step S1, wherein the melt stretching ratio during the spinning process is 250 to 2000; S3, drawing, shaping, and winding the filament bundle cooled in step S2 to obtain nonlinear polyester high-strength and high-modulus fibers.

2. The method for preparing a nonlinear polyester high-strength and high-modulus fiber according to claim 1, characterized in that: The nonlinear polyester chips in S1 include polyester bottle chips, polyester recycled bottles, polyester packaging sheets, polyester textiles or recycled polyester chips produced by processing polyester waste silk.

3. The method for preparing a nonlinear polyester high-strength and high-modulus fiber according to claim 1, characterized in that: The raw material pretreatment method in S1 includes melt filtration and re-granulation and slicing and drying the raw materials. The melt filtration uses a filter screen less than 25 microns to remove impurities, and the moisture content of the slices after drying is less than 50 ppm.

4. The method for preparing a nonlinear polyester high-strength and high-modulus fiber according to claim 1, characterized in that: The method for testing the purity of the raw materials in step S1 is: select a woven mesh of ≥1500 mesh or a sintered filter of ≤10 microns, and the filtration pressure rise value after the slices are melted and passed through the filter of the filtration performance instrument is less than 5.0Mpa / kg.

5. The method for preparing a nonlinear polyester high-strength and high-modulus fiber according to claim 1, characterized in that: In step S2, the melt extrusion method includes inputting the raw material into a screw extruder for high-temperature melting and extruding it into a spinning assembly, the temperature range of each zone of the screw is 270°C to 330°C, and the screw head pressure is 9 to 17 MPa.

6. The method for preparing a nonlinear polyester high-strength and high-modulus fiber according to claim 1, characterized in that: In step S2, the cooling method includes side-blowing air cooling and ring-blowing air cooling, the wind speed of the side-blowing air cooling is 0.3-1.5 m / s, the wind pressure of the ring-blowing air cooling is 200-1000 MPa, and the cooling air temperature is 15-80°C.

7. The method for preparing a nonlinear polyester high-strength and high-modulus fiber according to claim 1, characterized in that: In step S3, the filament bundle is drawn and shaped by a high-temperature hot roller, the preheating temperature of the drawing is room temperature to 100°C, the first roller speed is 2200 to 3500 m / min, the drawing ratio is 1.7 to 2.30, the maximum hot roller speed is 4600 to 6700 m / min; the temperature of the heat setting is 210 to 260°C.

8. The method for preparing a nonlinear polyester high-strength and high-modulus fiber according to claim 1, characterized in that: The nonlinear polyester high-strength and high-modulus fiber prepared in step S3 has a strength of >7.8 g / d, and a dimensional stability index of E%+H%<11%.

9. The method for preparing a nonlinear polyester high-strength and high-modulus fiber according to claim 1, characterized in that: The nonlinear polyester high-strength and high-modulus fiber prepared in step S3 is twisted and dipped to obtain a product that can be used in the fields of cord fabric skeleton materials, air spring cord fabric skeleton materials, industrial canvas, rubber hoses, etc.

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