Preparation method of polyester fiber with low oligomer content

Abstract

The present invention relates to a method for preparing polyester fibers with low oligomer content. The pre-oriented polyester fibers are made into polyester fibers with low oligomer content through a texturing process. The texturing process flow is: pre-oriented polyester fibers → the first feed roller → the twist stopper → the first texturing hot box → the over-alkali catalytic device → the cooling plate → the false twister → the second feed roller → the middle network → the second setting hot box → the setting feed roller → the surfactant spraying chamber → oiling → DTY winding and forming with overfeed → polyester fibers with low oligomer content. The temperature of the first texturing hot box is 215 ± 5°C. The over-alkali catalytic device includes an alkaline environment catalytic reaction chamber, in which an alkaline catalytic solution with a temperature of 135 ± 1°C is placed, and the liquid level line is not lower than the lowest point of a pair of wire winding rollers fixed in the alkaline environment catalytic reaction chamber. The present invention adds an over-alkali catalytic process and, in combination with the set temperature of the first texturing hot box, can fully react the oligomers precipitated under high-temperature conditions.

Description

Technical Field

[0001] The present invention belongs to the technical field of chemical fiber production and synthesis, and relates to a method for preparing polyester fiber with low oligomer content. Background Art

[0002] Polyester fiber is a synthetic chemical fiber, which is obtained by spinning after synthesizing polyethylene terephthalate (PET) from monomers terephthalic acid (PTA) and ethylene glycol (EG) through a polymerization reaction (polycondensation). Polyester fiber is widely used in the production of spinning and fabrics due to its advantages such as durability, heat resistance, chemical resistance, wrinkle resistance, and easy dyeing.

[0003] Due to the reversibility of the polymerization reaction process, in addition to the required linear polymer chains in the polymerization product, there are also some cyclic polymers and short linear polymers generated, collectively referred to as oligomers. The forms of oligomers are: cyclic trimer, cyclic dimer, chain dimer, chain trimer, etc. Among them, the proportion of the stable cyclic trimer form is relatively high. For example, in Document 1 ("Structural Characterization of Oligomers in Recycled Polyester Fibers" [J]. Journal of Textile Research, 2015, 36(4): 25-30. DOI: 10.13475 / j.fzxb.20140306806.), the oligomer content is 1.52%; Document 2 ("Removal of Surface Cyclic Trimers in Disperse Dyeing of Polyester Fibers" [J]. Overseas Textile Technology, 2001(6): 29-33.) mentions that cyclic trimer is a cyclic oligomer in polyethylene terephthalate, with a degree of polymerization of 3, a content of about 1.5%, accounting for more than 70% of the total oligomers, and the oligomer content is relatively high.

[0004] In order to reduce the oligomer content in polyester fiber, Patent CN108130615A discloses a method for reducing the oligomer content in polyester fiber. By introducing a branched-chain diol (2-ethyl-2-methyl-1,3-propanediol) segment into the molecular chain of polyester to obtain a modified polyester, the lowest content of cyclic oligomers in the prepared polyester fiber is 0.5%, and the lowest content of linear oligomers is 0.22%, and the content is still relatively high; at the same time, this patent adds a branched-chain diol to obtain a modified polyester, and there are differences in the molecular structure or physical property indexes of its products compared with traditional polyester fibers.

[0005] In addition, "white powder" will be generated during the dyeing of the greige fabric woven from polyester fiber. The main component of these powders is oligomers, which are by-products of the polymerization reaction process. After high-temperature dyeing, the oligomers are separated and penetrate out of the macromolecular chain. The generation of oligomers during the dyeing process has a series of adverse effects. First, the weight of the white greige fabric decreases after dyeing, causing certain economic losses to customers; second, even if the oligomers do not detach from the macromolecular chain, they will have a certain impact on the strength and other internal properties of polyester fiber; most importantly, it is difficult to collect the oligomers during the dyeing process, causing irreversible damage to the environment.

[0006] Therefore, it is of great significance to study a preparation method of polyester fiber with low oligomer content to solve the problems existing in the prior art. Summary of the Invention

[0007] The object of the present invention is to solve the problems existing in the prior art and provide a preparation method of polyester fiber with low oligomer content.

[0008] To achieve the above object, the technical scheme adopted by the present invention is as follows:

[0009] A preparation method of polyester fiber with low oligomer content, wherein the pre-oriented polyester fiber is made into polyester fiber with low oligomer content through a texturing process;

[0010] The texturing process flow is: pre-oriented polyester fiber → first feed roller → twist stopper → first heat setting box → over-alkali catalytic device → cooling plate → false twister → second feed roller → mid-network → second heat setting box → setting feed roller → surfactant spraying chamber → oiling → DTY winding forming with overfeed → polyester fiber with low oligomer content;

[0011] The temperature of the first heat setting box is 215 ± 5 °C; below this temperature, the molecular chains are not active enough; above this temperature, larger molecular chains are formed, both of which are not conducive to the stretching activity of molecular chains;

[0012] The over-alkali catalytic device includes an alkaline environment catalytic reaction chamber, in which a pair of winding rollers are fixedly installed. The two winding rollers in the pair are of the same size and at the same height. An alkaline catalytic solution with a temperature of 135 ± 1 °C is placed in the alkaline environment catalytic reaction chamber, and the liquid level line is not lower than the lowest point of the winding rollers.

[0013] As a preferred technical scheme:

[0014] For the above-mentioned preparation method of polyester fiber with low oligomer content, the over-alkali catalytic device further includes a solvent preparation device. An alkaline substance inlet and a catalyst inlet are respectively arranged at the top of the solvent preparation device. A heating device, a pH detector I, a temperature detector and a stirring impeller that do not contact each other are arranged in the bottom area of the solvent preparation device. The stirring impeller is driven by a stirring motor;

[0015] The solvent preparation device is communicated with the alkaline environment catalytic reaction chamber through a pipeline, and a transfer pump is installed on the pipeline;

[0016] A pH detector II is arranged below the liquid level line in the alkaline environment catalytic reaction chamber, and a drain port is arranged on one side of the bottom of the alkaline environment catalytic reaction chamber.

[0017] A method for preparing a polyester fiber with low oligomer content as described above, the alkaline substance inlet and the catalyst inlet are respectively connected to the top of the solvent preparation device through pipelines, and flow control valves are installed on the pipelines to regulate the flow rate of the alkaline catalyst solution.

[0018] A method for preparing a polyester fiber with low oligomer content as described above, the alkaline catalyst solution is composed of an alkaline substance and a catalyst. The alkaline substance is a NaOH solution with a concentration of 3 g / L, and the catalyst is OL-Igomex NU. The catalyst concentration in the alkaline catalyst solution is 2.0 ± 0.05 g / L.

[0019] A method for preparing a polyester fiber with low oligomer content as described above, after passing through the surfactant spray chamber, the mass content of the surfactant on the tow is 0.2 ± 0.05%. The surfactant is added to the surface of the tow. The purpose is that during the dyeing process, water combines with the hydrophilic group of the surfactant, and the lipophilic group at the other end of the surfactant brings out the surface oligomers, so as to achieve the purpose of removing a small amount of oligomers on the surface layer of the tow that have not been completely eliminated after setting during dyeing.

[0020] A method for preparing a polyester fiber with low oligomer content as described above, the oligomer content in the pre-oriented polyester fiber is 1.50 ± 0.30 wt%, and the oligomer content in the polyester fiber with low oligomer content is less than 0.3 wt%. The yarn containing extremely few oligomers has the unique gloss, oil repellency, strength, and stable fabric weight after dyeing of the high molecular polymer product; for the polyester fiber product after reducing oligomers, there are fewer oligomer crystals on the surface of the tow, increasing the spinnability and weaving efficiency of the tow.

[0021] A method for preparing a polyester fiber with low oligomer content as described above, the polyester fiber with low oligomer content is woven into a grey cloth and then subjected to high-temperature alkaline dyeing. The temperature of the high-temperature alkaline dyeing is 130 °C, and the pH value is 9 ± 1. The oligomer content of the grey cloth after dyeing does not exceed 0.2 wt%.

[0022] A method for preparing a polyester fiber with low oligomer content as described above, the pre-oriented polyester fiber is prepared by transporting a polyester melt with an intrinsic viscosity of 0.692 - 0.695 dL / g to a spinning device through a melt direct spinning process.

[0023] A method for preparing a polyester fiber with low oligomer content as described above, the specific preparation process of the pre-oriented polyester fiber is as follows: the polyester melt is transported into the spinning box through a melt pipeline, extruded through a spinneret, and then passes through a slow cooling zone, ring blowing cooling, oiling, and winding to obtain the pre-oriented polyester fiber.

[0024] The melt pipeline includes Melt Pipeline I and Melt Pipeline II; after melt polymerization, it enters the heat exchanger through Melt Pipeline I after being pressurized by a booster pump from the melt inlet. After the heat exchanger adjusts and controls the temperature of the spinning melt, it enters each line and spinning position from the melt outlet through Melt Pipeline II; a three-stage melt valve is configured in front of Melt Pipeline II to ensure that it is fully open during high-load production of the product structure, and part of the valve body of the three-stage melt valve is closed during low-load production of the product structure. Its main purpose is to obtain a controllable product structure, and the denier range of the tow that can be produced is 5D to 800D. Thus, it ensures that the melt is extruded from the booster pump to the spinneret, effectively controlling the flow rate of the melt in the 285°C high-temperature pipeline within the range of 3.50 ± 0.20 m / min and the residence time within the range of 30 ± 5 min, thereby preparing pre-oriented polyester fibers with fewer side reactions.

[0025] Principle of the invention:

[0026] In the process flow of texturing of the present invention, an over-alkali catalytic device is added between the first texturing hot box and the cooling plate, and the temperature of the first texturing hot box is set accordingly. During the stretching process, oligomers are removed; and a surfactant is added to the surface layer of the tow before oiling, so that trace oligomers can be further removed during the subsequent dyeing process. The first texturing hot box heats the polyester fiber to make the polymer molecular chains more active, achieving the effect of uniform stretching. For the polyester pre-oriented yarn, below 215°C, as the temperature increases, the stretching deformation is more sufficient, the molecular chains are more complete, and the amorphous region is less. Setting the temperature at 215 ± 5°C is beneficial to the full stretching of the unoriented macromolecular chains in the pre-oriented yarn; during the stretching process of the active macromolecular chains, the oligomers wrapped in the macromolecular chains precipitate out and adhere to the surface of the tow, which is beneficial to the next process of hydrolyzing cyclic oligomers by over-alkali catalysis; after passing through the first texturing hot box, it directly enters the alkaline catalytic chamber. During the stretching process after the filaments are heated, the oligomers that precipitate from the pre-oriented yarn to the surface layer of the tow are hydrolyzed into carboxylates and ethylene glycol under the condition of an alkaline catalyst and are removed. The relatively less linear oligomers can be removed together during the dyeing process through the process flow of adding surfactant spray, and there is no problem of oligomer pits removed after the finished yarn (in the prior art, during the high-temperature coloring process of the fabric, an alkaline catalyst is added to remove oligomers, and after the oligomers are removed from the fiber surface, there are oligomer pits, which affect the weight stability of the fabric and the stability of the refraction effect of the fabric).

[0027] Beneficial effects:

[0028] (1) For the preparation method of polyester fiber with low oligomer content of the present invention, an over-alkali catalytic process is added during the stretching deformation process, and the temperature of the first texturing hot box is set accordingly. Under alkaline conditions, the oligomers are catalytically reacted to generate carboxylates and ethylene glycol, effectively reacting the oligomers precipitated under high-temperature conditions; an additional surfactant process is added to the tow before oiling to precipitate trace oligomers during the dyeing process after the tow is processed into a fabric.

[0029] (2) The preparation method of a polyester fiber with low oligomer content according to the present invention adopts a melt pipeline with adjustable pipeline capacity to control the residence time of the melt in the pipeline from the source, reduce the oligomers generated by the degradation of the melt in the pipeline, reduce the circulation of inferior fluids of oligomers, and effectively protect the PET pump and the heat exchanger;

[0030] (3) The preparation method of a polyester fiber with low oligomer content according to the present invention has the characteristic of a small amount of oligomers, effectively reducing the environmental pollution caused by the generation of oligomers and reducing the loss of fabric weight per unit area caused by oligomers in the post-textile fabric; the color of the fabric after dyeing and finishing is stable, eliminating the influence of fiber oligomer pits on the fabric color. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] Figure 1 is a flow chart of the melt pipeline;

[0032] Figure 2 is a cross-sectional view of the melt pipeline;

[0033] Figure 3 is a top view of the over-alkali catalysis process;

[0034] Figure 4 is a process equipment diagram of the over-alkali catalysis process;

[0035] Figure 5 is a schematic diagram of the over-alkali catalysis device;

[0036] Figure 6 is a schematic diagram of the texturing process flow;

[0037] Among them, 1 - melt inlet; 2 - booster pump, 3 - melt pipeline Ⅰ; 4 - heat exchanger; 5 - melt distribution valve; 6 - melt outlet Ⅰ; 7 - Three - stage melt valve; 8 - Heat medium inlet; 9 - Melt pipe Ⅱ; 10 - Heat medium outlet; 11 - Melt outlet Ⅱ; 12 - Pipe housing; 13 - Heat medium chamber; 14 - Melt pipe housing; 15 - Melt chamber; 15 - 1 - Melt chamber Ⅰ, 15 - 2 - Melt chamber Ⅱ, 15 - 3 - Melt chamber Ⅲ; 16 - Motor; 17 - Belt pulley system; 18 - Tow; 19 - Winding roller; 20 - Alkaline environment catalytic reaction chamber; 21 - Outlet turning roller; 22 - Liquid level line; 23 - pH value detector Ⅱ; 24 - Drain outlet; 25 - Delivery pump; 26 - Stirring motor; 27 - Stirring impeller; 28 - pH value detector Ⅰ; 29 - Temperature detector; 30 - Heating device; 31 - Solvent preparation device; 32 - Flow control valve; 33 - Alkaline substance inlet; 34 - Catalyst inlet; 35 - Pre - oriented polyester fiber; 36 - First feeding roller; 37 - Twisting stopper; 38 - First texturing hot box; 39 - Over - alkaline catalytic device; 40 - Cooling plate; 41 - False - twister; 42 - Second feeding roller; 43 - Network nozzle; 44 - Second setting hot box; 45 - Setting feeding roller; 46 - Surfactant spraying chamber; 47 - Oiling device; 48 - Winding guide; 49 - Finished bobbin. Detailed implementation manners

[0038] The present invention will be further described below in conjunction with specific implementation manners. It should be understood that these embodiments are only used to illustrate the present invention and not to limit the scope of the present invention. In addition, it should be understood that after reading the content taught by the present invention, those skilled in the art can make various changes or modifications to the present invention, and these equivalent forms also fall within the scope defined by the appended claims of this application.

[0039] The test methods for the performance indicators in the embodiments and comparative examples of the present invention are as follows:

[0040] Denier, denier CV value: Refer to the standard of "GB / T 14343 - 2008 Chemical Fibers - Test Method for Linear Density of Filament Yarns", and use a YG086 - type lea - reel winder to test, weigh and calculate.

[0041] Breaking strength, breaking elongation, breaking strength CV value, breaking elongation CV value: Refer to the standard of "GB / T 14344 - 2008 Chemical Fibers - Test Method for Tensile Properties of Filament Yarns", and use a full - automatic strength and elongation tester to test the core - yarn breaking and fuzzing polyester fibers prepared in each embodiment.

[0042] Test method for the content of oligomers in fiber / blanket: Use the Soxhlet extraction method. Take 30 g of the sample, and the mass of the sample after removing the surface sizing agent is m1; use trichloroethylene as the solvent to extract the sample after removing the surface sizing agent, and the mass of the surface oligomers in the sample after extraction is m2; the oligomer content is (m2 / m1)×100%.

[0043] Example 1

[0044] A method for preparing a polyester fiber with low oligomer content is as follows:

[0045] The polyester melt with an intrinsic viscosity of 0.692 dl / g is transported through a melt pipe into a spinning box. After being extruded through a spinneret, it successively passes through a slow cooling zone, ring blowing cooling, oiling, and winding to obtain a pre-oriented polyester fiber with an oligomer content of 1.80 wt%. Then, the pre-oriented polyester fiber is processed through a texturing process to obtain a polyester fiber with low oligomer content. Among them, the length of the slow cooling zone is 45 mm, the temperature of the ring blowing cooling is 19 °C, the rotation speed of the oil agent pump during oiling is 23 r / min, and the winding speed is 2680 m / min.

[0046] As Figures 1 - 2 shown, the melt pipe includes a melt pipe I 3 and a melt pipe II 9. A three-stage melt valve 7 is configured in front of the melt pipe II 9. The cross-sectional diameters of the three-stage melt valve 7 are 100 mm, 80 mm, and 50 mm in sequence. The polyester melt enters the booster pump 2 through the melt inlet 1. After being pressurized by the booster pump 2, it enters the heat exchanger 4 through the melt pipe I 3 with a cross-sectional diameter of 150 mm. After the temperature of the spinning melt is adjusted and controlled by the heat exchanger 4, one branch of the polyester melt enters the melt distribution valve 5, and then enters each line and spinning position through the melt pipe II 9 from the melt outlet II 11. The other branch enters other lines and spinning positions through the melt outlet I 6.

[0047] The melt pipe II 9 is a circular multi-layer pipe. The melt pipe II 9 is composed of a pipe outer shell 12, a heat medium cavity 13, a melt pipe outer shell 14, and a melt cavity 15. The melt cavity 15 is composed of a melt cavity I 15-1, a melt cavity II 15-2, and a melt cavity III 15-3 (all with fully open openings). The outer periphery of the melt cavity 15 is the heat medium cavity 13. The heat medium cavity 13 is filled with liquid heat medium. The liquid heat medium enters the heat medium cavity 13 from the heat medium inlet 8 and flows out through the heat medium outlet 10 for circulation to maintain the melt temperature.

[0048] The liquid heat medium is Dowtherm RP, and its main component is hydrogenated terphenyl synthetic heat transfer oil. The temperature of the liquid heat medium is 285 °C.

[0049] The process parameters for preparing the pre-oriented polyester fiber are as follows: the length of the melt pipe is 95 m, the temperature of the melt pipe is 285 °C, the melt flow rate is 3.542 m / min, the flow rate is 1317 kg / h, and the residence time in the pipe is 26.82 min.

[0050] As Figure 6As shown in the figure, the texturing process flow is as follows: pre-oriented polyester fiber 35 → the first feeding roller 36 → the twist stopper 37 → the first texturing hot box 38 → the over-alkali catalytic device 39 → the cooling plate 40 → the false twister 41 → the second feeding roller 42 → the medium network (network nozzle 43) → the second setting hot box 44 → the setting feeding roller 45 → the surfactant spraying chamber 46 → oiling on the oiling device 47 → DTY winding forming overfeed (winding guide 48) → polyester fiber with low oligomer content (finished bobbin 49);

[0051] As Figures 3 - 5 shown in the figure, the over-alkali catalytic device includes an alkaline environment catalytic reaction chamber 20, a solvent preparation device 31 and an outlet turning roller 21 connected by pipelines. A pair of wire winding rollers 19 are fixedly installed in the alkaline environment catalytic reaction chamber 20. The wire winding rollers 19 are driven by a motor 16 and a pulley system 17. An alkaline catalytic liquid with a temperature of 136 °C is placed in the alkaline environment catalytic reaction chamber 20, and the liquid level line 22 is not lower than the lowest point of the wire winding rollers 19; The top of the solvent preparation device 31 is respectively provided with an alkaline substance inlet 33 and a catalyst inlet 34, and the alkaline substance inlet 33 and the catalyst inlet 34 are respectively connected to the top of the solvent preparation device 31 through pipelines. A delivery pump 25 and a flow control valve 32 are installed on the pipelines. When the alkaline catalytic liquid is lower than the liquid level line 22, the delivery pump 25 is turned on for replenishment, and the flow control valve 32 is used to regulate the flow of the alkaline catalytic liquid; A heating device 30, a pH detector I 28, a temperature detector 29 and a stirring impeller 27 that do not contact each other are arranged in the bottom area of the solvent preparation device 31. The stirring impeller 27 is driven by a stirring motor 26; A pH detector II 23 is arranged below the liquid level line 22 in the alkaline environment catalytic reaction chamber 20, and a drain port 24 is arranged on one side of the bottom of the alkaline environment catalytic reaction chamber 20;

[0052] The alkaline catalytic liquid is composed of an alkaline substance and a catalyst. The alkaline substance is a NaOH solution with a concentration of 3 g / L, and the catalyst is OLIGOMEX NU. The catalyst concentration in the alkaline catalytic liquid is 2.05 g / L;

[0053] The texturing process parameters are as follows: pre-network pressure 0.03 MPa, the temperature of the first texturing hot box 220 °C, the false twister speed ratio 1.78, the speed of the second feeding roller 720 m / min, the ratio of the speed of the second feeding roller to the speed of the first feeding roller 1.64, the main network pressure 0.13 MPa, the temperature of the second setting hot box 175 °C, the overfeed rate of the setting feeding roller -3.10%, the pump speed of the surfactant atomization pump 5.0 r / min, the overfeed rate of winding forming -3.75%;

[0054] After passing through the surfactant (the surfactant is an aqueous solution of sodium dodecylbenzenesulfonate with a concentration of 70 wt%, Zhejiang Transfar Chemical Co., Ltd.) spraying chamber, the mass content of the surfactant on the tow 18 is 0.18%.

[0055] The oligomer content in the finally obtained polyester fiber with low oligomer content is 0.30 wt%; the fineness of the polyester fiber with low oligomer content is 221.32 dtex, the fineness CV value is 0.39%, the number of filaments is 288 f, the breaking strength is 4.28 cN / dtex, the breaking strength CV value is 1.85%, the breaking elongation is 20.52%, the breaking elongation CV value is 6.66%, the surfactant content is 0.18%, and the cross-section integrity is 99.7%; after the polyester fiber with low oligomer content is woven into a grey cloth, it is subjected to high-temperature alkaline dyeing. The temperature of the high-temperature alkaline dyeing is 130 °C, the pH value is 9, and the oligomer content of the dyed grey cloth is 0.17 wt%.

[0056] Example 2

[0057] A preparation method of polyester fiber with low oligomer content is as follows:

[0058] The polyester melt with an intrinsic viscosity of 0.692 dL / g is transported through a melt pipeline into a spinning box. After being extruded through a spinneret plate, it successively passes through a slow cooling zone, ring blowing cooling, oiling, and winding to obtain a pre-oriented polyester fiber with an oligomer content of 1.78 wt%. Then, the pre-oriented polyester fiber is processed by a texturing process to obtain a polyester fiber with low oligomer content; among them, the length of the slow cooling zone is 50 mm, the temperature of the ring blowing cooling is 21 °C, the rotation speed of the oil agent pump during oiling is 9 r / min, and the winding speed is 3070 m / min;

[0059] The melt pipeline includes melt pipeline I and melt pipeline II. A three-stage melt valve is configured in front of melt pipeline II. The cross-sectional diameters of the three-stage melt valve are 73 mm, 46 mm, and 25 mm in sequence; the polyester melt enters a booster pump through a melt inlet. After being boosted by the booster pump, it enters a heat exchanger through melt pipeline I with a cross-sectional diameter of 98 mm. After the temperature of the spinning melt is adjusted and controlled by the heat exchanger, one branch enters a melt distribution valve, and then enters each line and spinning position through melt pipeline II from the melt outlet; the other branch enters other lines and spinning positions through melt outlet I;

[0060] Melt pipeline II is a circular multi-layer pipe. Melt pipeline II is composed of a pipeline outer shell, a heat medium chamber, a melt pipe outer shell, and a melt chamber. The melt chamber is composed of melt chamber I, melt chamber II, and melt chamber III (melt chamber I and melt chamber II are open, and melt chamber III is closed). The outer periphery of the melt chamber is the heat medium chamber, and the heat medium chamber is filled with liquid heat medium. The liquid heat medium enters the heat medium chamber from the heat medium inlet and flows out through the heat medium outlet for circulation to maintain the melt temperature;

[0061] The liquid heat medium is Dowtherm RP, and the main component is hydrogenated terphenyl synthetic heat transfer oil; the temperature of the liquid heat medium is 285 °C;

[0062] The preparation process parameters of the pre-oriented polyester fiber are as follows: the melt pipe length is 95 m, the melt pipe temperature is 285 °C, the melt flow rate is 3.461 m / min, the flow rate is 589 kg / h, and the residence time in the pipe is 27.45 min;

[0063] The texturing process flow is: pre-oriented polyester fiber → the first feed roller → the twist stopper → the first texturing hot box → the over-alkali catalytic device → the cooling plate → the false twister → the second feed roller → the middle network → the second setting hot box → the setting feed roller → the surfactant spraying chamber → oiling → DTY winding and forming with overfeed → polyester fiber with low oligomer content;

[0064] The over-alkali catalytic device includes an alkaline environment catalytic reaction chamber, a solvent preparation device, and an outlet turning roller connected by pipelines. A pair of wire winding rollers are fixedly installed in the alkaline environment catalytic reaction chamber, and the wire winding rollers are driven by a motor and a belt pulley system. An alkaline catalytic liquid with a temperature of 134 °C is placed in the alkaline environment catalytic reaction chamber, and the liquid level is not lower than the lowest point of the wire winding rollers;

[0065] The top of the solvent preparation device is respectively provided with an alkaline substance inlet and a catalyst inlet, and the alkaline substance inlet and the catalyst inlet are respectively connected to the top of the solvent preparation device through pipelines. A delivery pump and a flow control valve are installed on the pipelines, and the flow control valve is used to regulate the flow rate of the alkaline catalytic liquid; a heating device, a pH detector I, a temperature detector, and a stirring impeller that do not contact each other are arranged in the bottom area of the solvent preparation device, and the stirring impeller is driven by a stirring motor;

[0066] A pH detector II is arranged below the liquid level in the alkaline environment catalytic reaction chamber, and a drain port is arranged on one side of the bottom of the alkaline environment catalytic reaction chamber;

[0067] The alkaline catalytic liquid is composed of an alkaline substance and a catalyst. The alkaline substance is a NaOH solution with a concentration of 3 g / L, the catalyst is OLIGOMEX NU, and the catalyst concentration in the alkaline catalytic liquid is 2.00 g / L;

[0068] The texturing process parameters are as follows: the pre-network pressure is 0.03 MPa, the temperature of the first texturing hot box is 215 °C, the speed ratio of the false twister is 1.70, the speed of the second feed roller is 860 m / min, the ratio of the speed of the second feed roller to the speed of the first feed roller is 1.70, the main network pressure is 0.15 MPa, the temperature of the second hot box is 140 °C, the overfeed rate of the setting feed roller is -5.0%, the pump speed of the surfactant atomization pump is 2.0 r / min, and the overfeed rate of the winding and forming is -5.05%;

[0069] After passing through the surfactant (the surfactant is an aqueous solution of sodium dodecylbenzenesulfonate with a concentration of 70 wt%, Zhejiang Transfar Chemical Co., Ltd.) spraying chamber, the mass content of the surfactant on the tow is 0.15%;

[0070] The oligomer content in the finally obtained polyester fiber with low oligomer content is 0.25 wt%; the fineness of the polyester fiber with low oligomer content is 82.97 dtex, the CV value of the fineness of the polyester fiber with low oligomer content is 0.29%, the number of monofilaments is 72 f, the breaking strength is 4.50 cN / dtex, the CV value of the breaking strength is 2.19%, the breaking elongation is 20.55%, the CV value of the breaking elongation is 5.24%, the surfactant content is 0.15%, and the cross-sectional integrity is 99.9%; after the polyester fiber with low oligomer content is woven into a grey fabric, it is subjected to high-temperature alkaline dyeing. The temperature of the high-temperature alkaline dyeing is 130 °C, the pH value is 9, and the oligomer content of the dyed grey fabric is 0.14 wt%.

[0071] Example 3

[0072] A preparation method of polyester fiber with low oligomer content is as follows:

[0073] The polyester melt with an intrinsic viscosity of 0.695 dL / g is transported through the melt pipeline into the spinning box. After being extruded through the spinneret plate, it successively passes through the slow cooling zone, ring blowing cooling, oiling, and winding to obtain a pre-oriented polyester fiber with an oligomer content of 1.70 wt%. Then, the pre-oriented polyester fiber is processed by the texturing process to obtain the polyester fiber with low oligomer content; among them, the length of the slow cooling zone is 45 mm, the temperature of the ring blowing cooling is 19 °C, the rotation speed of the oil agent pump during oiling is 12.5 r / min, and the winding speed is 2850 m / min;

[0074] The melt pipeline includes Melt Pipeline I and Melt Pipeline II. A three-stage melt valve is configured in front of Melt Pipeline II. The cross-sectional diameters of the three-stage melt valve are 73 mm, 46 mm, and 25 mm in sequence; the polyester melt enters the booster pump through the melt inlet. After being pressurized by the booster pump, it enters the heat exchanger through Melt Pipeline I with a cross-sectional diameter of 98 mm. After adjusting and controlling the temperature of the spinning melt through the heat exchanger, one branch of the polyester melt enters the melt distribution valve, and then enters each line and spinning position through Melt Pipeline II from the melt outlet; the other branch enters other lines and spinning positions through Melt Outlet I;

[0075] Melt Pipeline II is a circular multi-layer pipe. Melt Pipeline II is composed of a pipeline shell, a heat medium chamber, a melt pipe shell, and a melt chamber. The melt chamber is composed of Melt Chamber I, Melt Chamber II, and Melt Chamber III (all with fully open openings). The outer periphery of the melt chamber is the heat medium chamber, and the heat medium chamber is filled with liquid heat medium. The liquid heat medium enters the heat medium chamber from the heat medium inlet and flows out through the heat medium outlet for circulation to maintain the melt temperature;

[0076] The liquid heat medium is Dowtherm RP, and the main component is hydrogenated terphenyl synthetic heat transfer oil; the temperature of the liquid heat medium is 285 °C;

[0077] The preparation process parameters of the pre-oriented polyester fiber are as follows: the melt pipe length is 95 m, the melt pipe temperature is 285 °C, the melt flow rate is 3.304 m / min, the flow rate is 860 kg / h, and the residence time in the pipe is 28.75 min;

[0078] The texturing process flow is as follows: pre-oriented polyester fiber → the first feed roller → the twist stopper → the first texturing hot box → the over-alkali catalytic device → the cooling plate → the false twister → the second feed roller → the middle network → the second setting hot box → the setting feed roller → the surfactant spray chamber → oiling → DTY winding forming with overfeed → polyester fiber with low oligomer content;

[0079] The over-alkali catalytic device includes an alkaline environment catalytic reaction chamber, a solvent preparation device, and an outlet turning roller connected by pipelines. A pair of wire winding rollers are fixedly installed in the alkaline environment catalytic reaction chamber. The wire winding rollers are driven by a motor and a pulley system. An alkaline catalytic liquid with a temperature of 135 °C is placed in the alkaline environment catalytic reaction chamber, and the liquid level is not lower than the lowest point of the wire winding rollers;

[0080] The alkaline catalytic liquid is composed of an alkaline substance and a catalyst. The alkaline substance is a NaOH solution with a concentration of 3 g / L, and the catalyst is OLIGOMEX NU. The catalyst concentration in the alkaline catalytic liquid is 2.00 g / L;

[0081] The top of the solvent preparation device is respectively provided with an alkaline substance inlet and a catalyst inlet, and the alkaline substance inlet and the catalyst inlet are respectively connected to the top of the solvent preparation device through pipelines. A delivery pump and a flow control valve are installed on the pipelines. The flow control valve is used to regulate the flow rate of the alkaline catalytic liquid; A heating device, a pH detector I, a temperature detector, and a stirring impeller that do not contact each other are arranged in the bottom area of the solvent preparation device. The stirring impeller is driven by a stirring motor;

[0082] A pH detector II is arranged below the liquid level in the alkaline environment catalytic reaction chamber, and a drain port is arranged on one side of the bottom of the alkaline environment catalytic reaction chamber;

[0083] The texturing process parameters are as follows: the pre-network pressure is 0.04 MPa, the temperature of the first texturing hot box is 210 °C, the speed ratio of the false twister is 1.65, the speed of the second feed roller is 880 m / min, the ratio of the speed of the second feed roller to the speed of the first feed roller is 1.67, the main network pressure is 0.12 MPa, the temperature of the second hot box is 150 °C, the overfeed rate of the setting feed roller is -5.5%, the pump speed of the surfactant atomization pump is 2.90 r / min, and the overfeed rate of the winding forming is -6.10%;

[0084] After passing through the surfactant (the surfactant is an aqueous solution of sodium dodecyl benzene sulfonate with a concentration of 70 wt%, Zhejiang Transfar Chemical Co., Ltd.) spray chamber, the mass content of the surfactant on the tow is 0.21%.

[0085] The oligomer content in the finally obtained polyester fiber with low oligomer content is 0.29 wt%; the fineness of the polyester fiber with low oligomer content is 119.57 dtex, the fineness CV value is 0.29%, the number of monofilaments is 216 f, the breaking strength is 4.15 cN / dtex, the breaking strength CV value is 1.81%, the elongation at break is 22.01%, the elongation at break CV value is 5.12%, the surfactant content is 0.17 wt%, and the cross-section integrity is 99.5%; after the polyester fiber with low oligomer content is woven into a grey fabric, high-temperature alkaline dyeing is carried out. The temperature of the high-temperature alkaline dyeing is 130 °C, the pH value is 9, and the oligomer content of the dyed grey fabric is 0.15 wt%.

[0086] Example 4

[0087] A preparation method of a polyester fiber with low oligomer content is as follows:

[0088] The polyester melt with an intrinsic viscosity of 0.694 dL / g is transported through a melt pipeline into a spinning box, extruded through a spinneret plate, and then passes through a slow cooling zone, ring blowing cooling, oiling, and winding in sequence to obtain a pre-oriented polyester fiber with an oligomer content of 1.63 wt%. Then, the pre-oriented polyester fiber is processed by a texturing process to obtain a polyester fiber with low oligomer content; among them, the length of the slow cooling zone is 62 mm, the temperature of the ring blowing cooling is 20 °C, the rotational speed of the oil agent pump during oiling is 3 r / min, and the winding speed is 2550 m / min;

[0089] The melt pipeline includes a melt pipeline I and a melt pipeline II. A three-stage melt valve is configured in front of the melt pipeline II. The cross-sectional diameters of the three-stage melt valve are 73 mm, 46 mm, and 25 mm in sequence; the polyester melt enters a booster pump through a melt inlet, is pressurized by the booster pump, and then enters a heat exchanger through the melt pipeline I with a cross-sectional diameter of 98 mm. After the temperature of the spinning melt is adjusted and controlled by the heat exchanger, one branch of the polyester melt enters a melt distribution valve, and then enters each line and spinning position through the melt pipeline II from the melt outlet; the other branch enters other lines and spinning positions through the melt outlet I;

[0090] The melt pipeline II is a circular multi-layer pipe. The melt pipeline II is composed of a pipeline shell, a heat medium cavity, a melt pipe shell, and a melt cavity. The melt cavity is composed of a melt cavity I, a melt cavity II, and a melt cavity III (the melt cavity I is open, and the melt cavity II and the melt cavity III are closed). The outer periphery of the melt cavity is the heat medium cavity, and the heat medium cavity is filled with liquid heat medium. The liquid heat medium enters the heat medium cavity from the heat medium inlet and flows out through the heat medium outlet for circulation to maintain the melt temperature;

[0091] The liquid heat medium is Dowtherm RP, and the main component is hydrogenated terphenyl synthetic heat transfer oil; the temperature of the liquid heat medium is 285 °C;

[0092] The preparation process parameters of the pre-oriented polyester fiber are as follows: the melt pipe length is 95 m, the melt pipe temperature is 283 °C, the melt flow rate is 3.417 m / min, the flow rate is 166 kg / h, and the residence time in the pipe is 27.80 min;

[0093] The texturing process flow is as follows: pre-oriented polyester fiber → the first feed roller → the twist stopper → the first texturing hot box → the over-alkali catalytic device → the cooling plate → the false twister → the second feed roller → the middle network → the second setting hot box → the setting feed roller → the surfactant spray chamber → oiling → DTY winding and forming with overfeed → polyester fiber with low oligomer content;

[0094] The over-alkali catalytic device includes an alkaline environment catalytic reaction chamber, a solvent preparation device, and an outlet turning roller connected by pipelines. A pair of wire winding rollers are fixedly installed in the alkaline environment catalytic reaction chamber. The wire winding rollers are driven by a motor and a pulley system. An alkaline catalytic liquid with a temperature of 134 °C is placed in the alkaline environment catalytic reaction chamber, and the liquid level is not lower than the lowest point of the wire winding rollers;

[0095] The alkaline catalytic liquid is composed of an alkaline substance and a catalyst. The alkaline substance is a NaOH solution with a concentration of 3 g / L, and the catalyst is OLIGOMEX NU. The catalyst concentration in the alkaline catalytic liquid is 1.95 g / L;

[0096] An alkaline substance inlet and a catalyst inlet are respectively arranged at the top of the solvent preparation device, and the alkaline substance inlet and the catalyst inlet are respectively connected to the top of the solvent preparation device through pipelines. A delivery pump and a flow control valve are installed on the pipelines. The flow control valve is used to regulate the flow rate of the alkaline catalytic liquid; A heating device, a pH detector I, a temperature detector, and a stirring impeller that do not contact each other are arranged in the bottom area of the solvent preparation device. The stirring impeller is driven by a stirring motor;

[0097] A pH detector II is arranged below the liquid level in the alkaline environment catalytic reaction chamber, and a drain port is arranged on one side of the bottom of the alkaline environment catalytic reaction chamber;

[0098] The texturing process parameters are as follows: the pre-network pressure is 0.02 MPa, the temperature of the first texturing hot box is 205 °C, the speed ratio of the false twister is 1.68, the speed of the second feed roller is 680 m / min, the ratio of the speed of the second feed roller to the speed of the first feed roller is 1.57, the main network pressure is 0.09 MPa, the temperature of the second hot box is 110 °C, the overfeed rate of the setting feed roller is -4.0%, the pump speed of the surfactant atomization pump is 2.0 r / min, and the overfeed rate of the winding and forming is -3.65%;

[0099] After passing through the surfactant (the surfactant is an aqueous solution of sodium dodecylbenzenesulfonate with a concentration of 70 wt%, Zhejiang Transfar Chemical Co., Ltd.) spray chamber, the mass content of the surfactant on the tow is 0.25%.

[0100] The oligomer content in the finally obtained polyester fiber with low oligomer content is 0.27 wt%; the fineness of the polyester fiber with low oligomer content is 22.34 dtex, the fineness CV value is 0.19%, the number of filaments is 72 f, the breaking strength is 4.47 cN / dtex, the breaking strength CV value is 2.13%, the elongation at break is 21.24%, the elongation at break CV value is 5.35%, the surfactant content is 0.21 wt%, and the cross-section integrity is 99.8%; after the polyester fiber with low oligomer content is woven into a grey cloth, high-temperature alkaline dyeing is carried out. The temperature of the high-temperature alkaline dyeing is 130 °C, the pH value is 9, and the oligomer content of the dyed grey cloth is 0.17 wt%.

Claims

1. A method for preparing a polyester fiber with low oligomer content, characterized in that: Pre-oriented polyester fibers are made into polyester fibers with low oligomer content through the texturing process; The texturing process flow is: pre-oriented polyester fibers → the first feed roller → the first texturing hot box → the over-alkali catalytic device → the cooling plate → the false twister → the second feed roller → the middle network → the second setting hot box → the setting feed roller → the stop twister → the surfactant spraying chamber → oiling → DTY winding and forming with overfeed → polyester fibers with low oligomer content; The temperature of the first texturing hot box is 215 ± 5 °C; The over-alkali catalytic device includes an alkaline environment catalytic reaction chamber, in which a pair of wire winding rollers are fixedly installed. An alkaline catalytic liquid with a temperature of 135 ± 1 °C is placed in the alkaline environment catalytic reaction chamber, and the liquid level line is not lower than the lowest point of the wire winding rollers.

2. The preparation method of a polyester fiber with low oligomer content according to claim 1, characterized in that, The over-alkali catalytic device also includes a solvent preparation device. An alkaline substance inlet and a catalyst inlet are respectively arranged at the top of the solvent preparation device. A heating device, a pH detector I, a temperature detector and a stirring impeller that do not contact each other are arranged in the bottom area of the solvent preparation device. The stirring impeller is driven by a stirring motor; The solvent preparation device is communicated with the alkaline environment catalytic reaction chamber through a pipeline, and a delivery pump is installed on the pipeline; A pH detector II is arranged below the liquid level line in the alkaline environment catalytic reaction chamber, and a drain port is arranged on one side of the bottom of the alkaline environment catalytic reaction chamber.

3. The preparation method of a polyester fiber with low oligomer content according to claim 2, characterized in that, The alkaline substance inlet and the catalyst inlet are respectively connected to the top of the solvent preparation device through pipelines, and flow control valves are installed on the pipelines to regulate the flow rate of the alkaline catalytic liquid.

4. The preparation method of a polyester fiber with low oligomer content according to claim 3, characterized in that, The alkaline catalytic liquid is composed of an alkaline substance and a catalyst. The alkaline substance is a NaOH solution with a concentration of 3 g / L, and the catalyst is OL-Igomex NU. The catalyst concentration in the alkaline catalytic liquid is 2.0 ± 0.05 g / L.

5. The preparation method of a polyester fiber with low oligomer content according to claim 1, characterized in that, After passing through the surfactant spraying chamber, the mass content of the surfactant on the tow is 0.2 ± 0.05%.

6. The preparation method of a polyester fiber with low oligomer content according to claim 1, characterized in that, The oligomer content in the pre-oriented polyester fibers is 1.50 ± 0.30 wt%, and the oligomer content in the polyester fibers with low oligomer content is less than 0.35 wt%.

7. The method for preparing a polyester fiber with low oligomer content according to claim 6, characterized in that, The polyester fibers with low oligomer content are woven into a white greige fabric and then subjected to high-temperature alkaline dyeing. The temperature of the high-temperature alkaline dyeing is 130 °C, the pH value is 9 ± 1, and the oligomer content in the white greige fabric after dyeing ≤ 0.2 wt%.

8. A method for preparing a polyester fiber with low oligomer content according to claim 1, characterized in that, The pre-oriented polyester fibers are prepared by conveying a polyester melt with an intrinsic viscosity of 0.692 - 0.695 dL / g to a spinning device through the melt direct spinning process.

9. The preparation method of a polyester fiber with low oligomer content according to claim 8, characterized in that, The specific preparation process of the pre-oriented polyester fibers is: the polyester melt is conveyed into the spinning box through the melt pipeline, extruded through the spinneret plate, and then passes through the slow cooling zone, ring blowing cooling, oiling and winding in sequence to obtain the pre-oriented polyester fibers.

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