A preparation method of PTT top

Abstract

This application relates to the technical field of wool top products, and specifically discloses a preparation method of PTT wool top. The preparation method of PTT wool top includes: raw material drying → screw extrusion spinning → winding and bundling → post-treatment of tow → cutting and strip-making of tow → first gilling → second gilling → ball-forming gilling; in the raw material drying process: drying is carried out with modified PTT polyester chips as raw materials, and the preparation method of the modified PTT polyester chips includes: esterification reaction: mixing 1,3-propanediol with terephthalic acid for reaction, and adding an esterification catalyst and an auxiliary agent at the same time, until the esterification water discharge is completed, and the reaction is ended to obtain a polymerization monomer; polymerization reaction: mixing an organic-inorganic hybrid microsphere containing a sulfonic acid group on the surface with the polymerization monomer, and carrying out polymerization and pelletizing in the presence of a polymerization catalyst and a stabilizer to obtain PTT polyester chips. By modifying the PTT polyester in this application, the PTT wool top has a good dye uptake rate for cationic dyes, broadening the application field.

Description

Technical Field

[0001] This application relates to the technical field of woolen products, and more specifically, it relates to a method for preparing PTT wool top. Background Art

[0002] The odd-carbon effect of the three methylene groups in the molecular structure of polytrimethylene terephthalate (PTT) makes the resilience and softness of PTT fibers superior to those of polyester and polyamide fibers, and it has natural antistatic properties. The wool top made of PTT fibers has a soft handfeel and resilience, and excellent skin-friendly performance, and is widely used in fields such as carpets and sportswear. However, PTT fibers cannot be dyed with cationic dyes with good environmental protection effects and bright dyeing colors, and can only be dyed with disperse dyes. The cost of disperse dyeing is high and the environmental protection is poor, and the color is not as bright and beautiful as that of polyester and polyamide fibers dyed with cationic dyes.

[0003] Therefore, due to the limitations of dyeing, PTT fibers and their fabrics severely restrict the development of this product in the application fields. Summary of the Invention

[0004] In order to solve the problem of poor uptake rate of cationic dyes by PTT wool top, this application provides a method for preparing PTT wool top.

[0005] A method for preparing PTT wool top provided by this application adopts the following technical scheme:

[0006] A method for preparing PTT wool top includes the following technological steps: raw material drying → screw extrusion spinning → winding and bundling → post-treatment of tow → cutting and forming of tow into strips → first gilling → second gilling → balling gilling;

[0007] In the raw material drying process: drying is carried out with modified PTT polyester chips as raw materials. The preparation method of the modified PTT polyester chips includes the following steps:

[0008] S10, esterification reaction: Mix 1,3-propanediol and terephthalic acid for reaction, and at the same time add an esterification catalyst and an auxiliary agent until the esterification water discharge is completed, and end the reaction to obtain a polymerization monomer;

[0009] S20, polymerization reaction: Mix an organic-inorganic hybrid microsphere with a sulfonic acid group on the surface with the polymerization monomer, and carry out polymerization in the presence of a polymerization catalyst and a stabilizer to obtain a modified PPT polyester. The obtained modified PTT polyester is pelletized to obtain PTT polyester chips.

[0010] By adopting the above technical solution, the PTT polyester chips are modified by using organic-inorganic hybrid microspheres with a large number of sulfonic acid groups on the surface, so that a large number of sulfonic acid groups are introduced into the PTT fibers. These groups can form strong interactions with cationic dyes, enabling the PTT fibers to be dyed with cationic dyes, maintaining the original excellent properties of PTT and improving its dyeability. The modified PTT fibers and their fabrics can be dyed with cations at normal temperature and pressure to obtain PTT fiber products with bright colors, further expanding the application fields of PTT top.

[0011] Preferably, the preparation method of the organic-inorganic hybrid microspheres is as follows: silica gel particles, a silanizing reagent containing a mercapto group, and toluene are ultrasonically mixed and reacted, and the supernatant is removed by centrifugation, followed by washing and drying to obtain silica gel particles modified with silane; the silane particles modified with silanization, sodium allyloxyhydroxypropyl sulfonate, and an initiator are ultrasonically mixed and reacted, and the supernatant is removed by centrifugation, followed by washing and drying; the mass ratio of the silica gel particles to the silanizing reagent containing a mercapto group is 1:(0.5-1); the mass ratio of the silane particles modified with silanization to sodium allyloxyhydroxypropyl sulfonate is 1:(1-10).

[0012] By adopting the above technical solution, the thiol-ene click chemistry method is used, with mild reaction conditions, fast reaction speed, high reaction efficiency, narrow particle size distribution of the obtained organic-inorganic hybrid microsphere particles, monodisperse particle size, and a large number of sulfonic acid groups on the surface at the same time, which has a good modification effect on PTT polyester and strong adsorption performance.

[0013] Preferably, the initiator is an azo initiator, including one or more of azobisisobutyronitrile, azobisisoheptonitrile, azobis(isobutylamidine) hydrochloride, and azobis(isobutylethyl)imidazoline hydrochloride.

[0014] By adopting the above technical solution, azo initiators have many advantages compared with peroxide initiators. They have low oxidation ability, can decompose at a suitable speed at 50-80 °C, the decomposition characteristics show a first-order reaction, there is no induced decomposition; at the same time, the decomposition speed is less affected by the solvent, there is no induced decomposition, and it will not explode when colliding. The product is easy to purify, cheap in price, and stable and safe to store.

[0015] Preferably, in S10, the temperature during the esterification reaction is raised from 220 °C to 250 °C at a gradient of 3 °C / 10 min.

[0016] By adopting the above technical solution, during esterification, the temperature should not be directly raised to a relatively high value or increased at a relatively fast rate, as this will cause a large amount of 1,3-propanediol in the system to escape, resulting in the failure of the reaction. However, an overly slow heating rate will lead to difficulties in the esterification reaction and an extended reaction time. A heating rate of 3°C / 10 min can stably and effectively control the esterification process. At the same time, increasing the temperature can accelerate the esterification reaction, but a reaction temperature above 250°C cannot effectively shorten the esterification time. Considering that too high a temperature may increase the possibility of side reactions, it is more appropriate to control the maximum temperature of the esterification reaction at 250°C.

[0017] Preferably, in S10 and S20, the catalyst is one of tetrabutyl titanate, stannous octoate, antimony trioxide, antimony acetate, zinc acetate, cobalt acetate, and manganese acetate, and the catalyst dosage is 0.035-0.055% of terephthalic acid; more preferably, the catalyst is tetrabutyl titanate.

[0018] By adopting the above technical solution, adding a catalyst can greatly promote the esterification and polymerization reactions. The electronegativity of metal atoms in metal catalysts has an important influence on the catalytic activity. An increase in electronegativity is beneficial to increasing the positive charge of the terephthalic acid carbonyl, thereby improving the catalytic activity. However, too large an electronegativity is not conducive to the removal of the metal from the reaction substrate, thus affecting its activity. Titanium-based, zinc-based, tin-based, and antimony-based catalysts have become catalysts with relatively high activity during polyester synthesis due to their moderate electronegativity and strong coordination ability with carbonyl oxygen. And the order of catalytic activity in the esterification reaction is: tetrabutyl titanate > zinc acetate > stannous octoate > cobalt acetate ≥ manganese acetate > antimony acetate ≥ antimony trioxide. As the dosages of tetrabutyl titanate, zinc acetate, and stannous octoate increase, the rate of the polycondensation reaction increases accordingly, which is more obvious in the initial stage of the reaction. However, the maximum intrinsic viscosity that the product can obtain is achieved when the reaction is catalyzed by a suitable dosage of the catalyst. This is because too high a catalyst dosage may cause a rapid increase in side reactions such as thermal oxidative degradation, resulting in a decrease in the molecular weight of the system. Therefore, adding an appropriate amount of catalyst can obtain PTT polyester with the maximum intrinsic viscosity.

[0019] Preferably, in S10, the mass ratio of terephthalic acid to 1,3-propanediol is 1:(1-2).

[0020] By adopting the above technical solution, as the content of 1,3-propanediol increases, the reaction rate becomes faster and the esterification time becomes shorter. However, in the later stage of the esterification reaction, a certain degree of polymerization occurs between the generated esters, generating some oligomers such as dimers and trimers, and releasing 1,3-propanediol. Therefore, it is not necessary to use an excessive amount of 1,3-propanediol during esterification. Therefore, selecting an appropriate mass ratio of terephthalic acid to 1,3-propanediol can shorten the esterification time and improve the esterification rate simultaneously.

[0021] Preferably, in S20, the temperature during the polymerization reaction is 260 - 275 °C, and the polymerization time is 175 - 300 °C.

[0022] By adopting the above technical solution, at different polymerization temperatures, the intrinsic viscosity of the reactants increases to a certain maximum value with the increase of the polycondensation time and then decreases. A higher polymerization temperature can make the reaction faster, but it does not necessarily always result in a polycondensation product with a higher intrinsic viscosity. To obtain a product with a higher intrinsic viscosity, it is necessary to control the reaction time and select an appropriate polymerization temperature. If the reaction time is too short or the temperature is too low, the reaction proceeds slowly and cannot effectively improve the intrinsic viscosity of the polymer; if the time is too long or the temperature is too high, side reactions such as thermal oxidative degradation will cause the viscosity of the system to decrease.

[0023] Preferably, after the esterification reaction is completed and before the polymerization reaction, a nucleating agent is added to the polymerization monomer, and the nucleating agent is one of calcium carbonate, talcum powder, barium sulfate, silicon dioxide, and titanium dioxide.

[0024] By adopting the above technical solution, due to the unique helical molecular internal structure of PTT polyester, this polyester variety is more prone to crystallization, which causes difficulties in the subsequent spinning process. In this application, the crystallinity of the fiber surface is controlled by adding a nucleating agent during the polymerization process to ensure stable spinning conditions during the spinning process, so that the fiber is dyed evenly. The nucleating agent can not only promote the fiber crystallization process, but also enhance the strength of the fiber and improve the spinnability of the chips.

[0025] Preferably, an antifoaming agent is added while adding the nucleating agent.

[0026] By adopting the above technical solution, the antifoaming agent can prevent bumping when adding the nucleating agent.

[0027] Preferably, in the raw material drying process, 0.05 - 0.07% of calcium stearate is also added to the modified PTT polyester chip raw material.

[0028] By adopting the above technical solution, calcium stearate can improve the fluidity of the modified PTT polyester chip raw material in the subsequent screw extrusion and spinning process.

[0029] In summary, the present application has the following beneficial effects:

[0030] 1. In this application, an organic-inorganic hybrid microsphere with a large number of sulfonic acid groups on its surface is used to modify PTT polyester chips, introducing a large number of sulfonic acid groups into PTT fibers. Through the strong adsorption effect formed by these groups and cationic dyes, PTT top can be dyed with cationic dyes, thus broadening the application field of PTT top; 2. In this application, the thiol-ene click chemistry method is adopted, with mild reaction conditions, fast reaction speed and high reaction efficiency. The obtained organic-inorganic hybrid microsphere particles have a narrow particle size distribution, monodisperse particle size, and a large number of sulfonic acid groups on the surface, which has a good modification effect on PTT fibers and strong adsorption performance at the same time;

[0031] 3. In this application, the crystallinity of the fiber surface is controlled by adding a nucleating agent during the polymerization process to ensure stable spinning conditions during the spinning process, so that the fiber is dyed evenly. The nucleating agent can not only promote the fiber crystallization process, but also enhance the strength of the fiber and improve the spinnability of the chips. Detailed implementation mode

[0032] The following further elaborates on this application in combination with preparation examples and implementation examples.

[0033] Preparation example

[0034] Preparation example 1

[0035] The following takes Preparation example 1 as an example for illustration. The preparation example of this application discloses a preparation method of an organic-inorganic hybrid microsphere, and the specific method is as follows:

[0036] S100, in a flask, add 80 ml of toluene, 6 g of silica gel particles with a particle size of 5 μm, 3 g of 3-mercaptopropyltriethoxysilane, ultrasonically mix evenly for 1 min, connect a condenser to the flask, add a magnetic stirrer, and keep the magnetic stirrer at a speed of 300 r / min. The reaction device is placed in an oil bath, heated under reflux for 6 h, then stop the reaction, cool to room temperature, and then use a high-speed centrifuge to centrifuge at a speed of 10,000 r / min to remove the supernatant. Filter and wash successively with toluene, acetone, methanol, and acetone, repeat the filtration and washing 3 times, and vacuum dry in a vacuum drying oven at 50 °C for 24 h to obtain silica gel particles modified with silane;

[0037] S200. Install a condenser in a flask, add 50 ml of a reaction solvent water-ethanol mixed solution (volume ratio 2:1), add 1 g of silica gel particles modified with silane, 1 g of allyloxyhydroxypropylsulfonic acid sodium salt, and 0.1 g of azobisisobutyronitrile, ultrasonically mix for 1 minute, then purge with nitrogen for 15 minutes, add a magnetic stirrer, and keep the magnetic stirrer at a speed of 300 r / min. The reaction device is placed in an oil bath and heated evenly and slowly, and the temperature is raised to 75 °C within 30 minutes; maintain the reaction at 75 °C for 12 hours, stop the reaction, cool to room temperature to obtain microsphere particles, then use a high-speed centrifuge to centrifuge at a speed of 10,000 r / min, remove the supernatant, add the reaction solution and wash 3 times, and vacuum dry in a vacuum oven at 50 °C for 24 hours. In this preparation example, azobisisobutyronitrile is selected as the initiator, and in other preparation examples, one or more of azobisisoheptonitrile, azobis(isobutyramidine) hydrochloride, and azobis(isobutyl ether azoline) hydrochloride can also be selected.

[0038] Preparation Example 2

[0039] This preparation example is basically the same as Preparation Example 1, except that: in S100, 6 g of silica gel particles with a particle size of 5 μm and 6 g of 3-mercaptopropyltriethoxysilane are added; in S20, 1 g of silica gel particles modified with silane and 10 g of allyloxyhydroxypropylsulfonic acid sodium salt are added.

[0040] Preparation Example 3

[0041] The preparation example of this application discloses a preparation method of modified PTT polyester chips, and the specific method is as follows:

[0042] S10. Add 16.6 Kg of terephthalic acid and 7.6 Kg of 1,3-propanediol to a reaction kettle, add 6.3 g of tetrabutyl titanate and 0.5 g of sodium acetate, stir evenly, then start to heat up to 220 °C and pressurize to 0.3 Mpa for esterification. During esterification, the temperature is increased to 250 °C at a gradient of 3 °C / 10 min. After the esterification water is discharged, return to normal pressure and end the esterification reaction to obtain a polymerization monomer;

[0043] S20. Add 9.9 g of tetrabutyl titanate and 1 g of triphenyl phosphate to the above polymerization monomer, heat up, turn on the vacuum system, control the temperature at 250 °C, after 40 minutes, end at low vacuum (below 2.0 Kpa). Under vacuum conditions, close the vacuum valve, add 0.1 g of organic-inorganic hybrid microspheres to 1 L of a diol solution to form a mixed solution, add the mixed solution to the reaction kettle, close the feeding valve, turn on the vacuum valve, and enter high vacuum; control the polymerization temperature at 260 °C, polymerize for 300 minutes, and the vacuum degree < 40 Pa. After the polymerization is completed, obtain modified PTT polyester, and cut the modified PTT polyester into chips; among them, the organic-inorganic hybrid microspheres are obtained from Preparation Example 1.

[0044] Preparation Example 4

[0045] This preparation example is basically the same as Preparation Example 3, except that in S20, the organic-inorganic hybrid microspheres are obtained from Preparation Example 2.

[0046] Preparation Example 5

[0047] This preparation example is basically the same as Preparation Example 3, except that in S10, 16.6 Kg of terephthalic acid and 10.64 Kg of 1,3-propanediol are added to the reaction kettle.

[0048] Preparation Example 6

[0049] This preparation example is basically the same as Preparation Example 3, except that in S10, 16.6 Kg of terephthalic acid and 15.2 Kg of 1,3-propanediol are added to the reaction kettle.

[0050] Preparation Example 7

[0051] This preparation example is basically the same as Preparation Example 5, except that in S20, the polymerization temperature is 275 °C and the polymerization time is 175 °C.

[0052] Preparation Example 8

[0053] This preparation example is basically the same as Preparation Example 5, except that in S20, 9.9 g of tetrabutyl titanate and 1 g of triphenyl phosphate are added to the above polymerization monomers, and methyl silicone oil is added. The temperature is raised, and the vacuum system is turned on. The temperature is controlled at 250 °C. After 40 min, the low vacuum (below 2.0 KPa) ends. Under the vacuum state, the vacuum valve is closed, 0.1 g of organic-inorganic hybrid microspheres are added to 1 L of diol solution to form a mixed solution, the mixed solution and 0.05 g of calcium carbonate are added to the reaction kettle, the feeding valve is closed, the vacuum valve is opened, and high vacuum is entered; the polymerization temperature is controlled at 260 °C, the polymerization is carried out for 300 min, and the vacuum degree < 40 Pa. After the polymerization is completed, the modified PTT polyester is obtained. The modified PTT polyester is pelletized to obtain modified PTT polyester chips; in this application, calcium carbonate is selected as the nucleating agent, and in other embodiments, talc powder, barium sulfate, silicon dioxide or titanium dioxide can also be selected.

[0054] Example

[0055] Examples 1-7

[0056] The embodiments of this application disclose a method for preparing PTT top fibers, and the specific method is as follows:

[0057] S1. Add 1000 Kg of modified PTT polyester chips and 50 g of calcium stearate into a vacuum drum device for drying. When feeding the raw materials of the modified PTT polyester chips, the temperature of the drum is 55 °C. After the feeding is completed, evacuate the drum to make the vacuum degree inside the drum 0.1 Mpa. At the same time, heat the drum to raise the temperature of the drum to 130 °C and keep it for 5 h. The steam pressure during the temperature rise of the drum is 0.1 Mpa, and the steam pressure during the heat preservation of the drum is 0.4 Mpa. After the heat preservation is completed, cool the drum for 1 h to make the discharge temperature of the raw materials of the modified PTT polyester chips 120 °C. The moisture content of the raw materials of the modified PTT polyester chips after drying is less than 0.005%. The modified PTT polyester chips are obtained by using Preparation Example 3.

[0058] S2. Melt and extrude and spin the dried modified PTT polyester chips in a screw extruder. The modified PTT polyester chips are pushed by a screw with a rotation speed of 50 m / s and pass through Zone 1 and Zone 2 of the screw extruder for preheating in sequence. The temperature of Zone 1 is 250 °C, and the temperature of Zone 2 is 255 °C. Then pass through Zone 3 and Zone 4 for melting in sequence. The temperature of Zone 3 is 260 °C, and the temperature of Zone 4 is 260 °C. Then pass through Zone 5 and Zone 6 in sequence and are quantitatively distributed to each spinning station for extrusion and spinning. The number of holes in the spinneret used at each spinning station is 900. The temperature of Zone 5 is 255 °C, and the temperature of Zone 6 is 250 °C. The filament bundles obtained by spinning at each spinning station respectively enter a filament chamber with a temperature of 30 °C for ring blowing and curing. The ring blowing air volume is 1000 m / s, and the ring blowing air supply temperature is 28 °C. The dry heat shrinkage rate of the obtained filament bundles should reach 45%.

[0059] S3. Pass the filament bundles obtained at each spinning station through a feed wheel and a traction roller group in sequence for bundling to obtain a single-strand PTT fiber bundle. During bundling, the speeds of the traction roller group and the feed wheel are both 900 n / min.

[0060] S4. Pass multiple single-strand PTT fiber tows through tension rollers and tension and re-bundle them on the tension roller set to obtain a PTT fiber tow; then immerse the PTT fiber tow in a spinning finish for lubrication, and then pass the PTT fiber tow through the first drafting roller set. The rotational speed of the first drafting roller set is the same as that of the tension balls. Then, subject the PTT fiber tow passing through the first drafting roller set to the first oil bath. The temperature of the first oil bath is 65°C, the concentration ratio of the finish is 0.6%, and the polyester spinning finish for practical use in the oil bath is used. Then, pass the PTT fiber tow after the oil bath through the second drafting roller set. The rotational speed of the second drafting roller set is faster than that of the first drafting roller set, so that the PTT fiber tow undergoes a first draft of 3 times. Feed the PTT fiber tow after the second draft into a steam box to spray steam at 90°C, and then pass the PTT fiber tow through the third drafting roller set. The rotational speed of the third drafting balls is faster than that of the second drafting roller set, so that the PTT fiber tow undergoes a second draft of 1.2 times. Perform oil rolling and preheating on the PTT fiber tow after the second draft. The preheating temperature is 100°C. Then, crimp the preheated PTT fiber tow on a crimper. The main crimping pressure is 4 Mpa, the back crimping pressure is 3 Mpa, and the number of crimps is 28 per 25 mm. Then, perform heat setting on the crimped PTT fiber tow. The heat setting is divided into three temperature segments at one time. The temperatures of the three temperature segments are 110°C, 115°C, and 110°C in sequence, and the heat setting time for each temperature segment is 10 min. After the heat setting is completed, the finished tow is obtained;

[0061] S5. Cut the finished tow into strips on a cutting and slitting machine, and then perform first passage gilling, second passage gilling, and balling gilling on a gilling machine to finally obtain PTT top.

[0062] Examples 2 - 6

[0063] This example is basically the same as Example 1, except that different preparation examples are used for the modified PTT polyester chips, as shown in Table 1 specifically.

[0064] Table 1 Preparation examples of modified PTT polyester chips in Examples 1 - 6

[0065]

[0066] Example 7

[0067] The difference between this example and Example 3 is that in S1, 1000 Kg of modified PTT polyester chips and 70 g of calcium stearate are added to a vacuum rotary drum device for drying.

[0068] Comparative example

[0069] Comparative example 1

[0070] The difference between this comparative example and Example 1 is that in Preparation Example 3, no organic-inorganic hybrid microspheres are added, that is, the PTT polyester is not modified.

[0071] Comparative Example 2

[0072] The difference between this comparative example and Example 1 is that the organic-inorganic hybrid microspheres are replaced with isophthalic acid-5-sulfonate.

[0073] Performance detection test

[0074] PTT top obtained from Examples 1-7 with the same weight was used as Test Samples 1-7, and PTT top obtained from Comparative Examples 1-2 with the same weight as the test samples was used as Control Samples 1-2. The test samples and control samples were subjected to dyeing detection, and the results are shown in Table 2.

[0075] During dyeing, after adding water to the PTT top according to a bath ratio of 1:30, 4% of dissolved disperse cationic red SD-GRL, 3% of sodium sulfate, and 2% of acetic acid were added. The temperature was raised to 60 °C at a rate of 3 °C / min and run for 15 min, then the temperature was raised to 100 °C at a rate of 1.5 °C / min. After running for 60 min, the temperature was lowered to 40 °C at a rate of 3 °C / min and then drained. The dyed top was washed twice with clear water, and finally the dyed top was dried after drying or functional finishing.

[0076] Refer to GB / T2397-2003 to determine the dyeing exhaustion of PTT top;

[0077] Refer to GB / T9337-2001 to determine the dyeing uptake rate of PTT top;

[0078] Refer to GB / T3921-1997 to determine the washing fastness of PTT top during dyeing;

[0079] Refer to GB / T3920-1997 to determine the light fastness of PTT top during dyeing;

[0080] Refer to GB / T5718-1997 to determine the heat fastness (180 °C) of PTT top during dyeing.

[0081] Table 2 Performance detection data table

[0082]

[0083] Referring to Table 2 and combining Examples 1 and Comparative Examples 1-2, it can be seen that after modifying PTT polyester chips with organic-inorganic hybrid microspheres containing a large number of sulfonic acid groups on the surface, the organic-inorganic hybrid microspheres adopt the thiol-ene click chemistry method, with mild reaction conditions, fast reaction speed, high reaction efficiency, narrow particle size distribution of the obtained microspheres, monodisperse particle size, and a large number of sulfonic acid groups on the surface at the same time, which can adsorb cationic dyes, resulting in a high dye uptake rate between the PTT top and cationic dyes, maintaining the original excellent properties of the PTT top and improving its dyeability; at the same time, after the PTT top is washed with water, the cationic dyes are not easily detached from the fiber. After the PTT top prepared by the present invention is dyed with cationic dyes, the build-up power, color yield, wash fastness, light fastness and heat fastness grades of the PTT top are all improved compared with those of the PTT top made from the existing isophthalic acid-5-sulfonate modified PTT polyester chips and ordinary PTT polyester chips.

[0084] Referring to Table 2 and combining Examples 1, 3 and 4, it can be seen that within an appropriate range, changing the molar ratio of terephthalic acid to 1,3-propanediol, the PTT tops prepared from the modified PTT polyester chips all have good dye uptake rates for cationic dyes; as the content of 1,3-propanediol increases, the reaction rate is faster and the esterification time is shorter; however, in the later stage of the esterification reaction, a certain degree of polymerization occurs between the generated esters, generating some oligomers such as dimers and trimers, and releasing excess 1,3-propanediol. Therefore, it is not necessary to use an excessive amount of 1,3-propanediol during the esterification reaction.

[0085] Referring to Table 2 and combining Examples 3 and 5, it can be seen that within an appropriate range, changing the temperature and time during the polymerization reaction, the PTT tops obtained all have good dye uptake rates for cationic dyes. During the polymerization reaction, if the reaction time is too short or the temperature is too low, the reaction proceeds slowly and cannot effectively increase the viscosity of the polymer; while if the time is too long or the temperature is too high, the viscosity of the system will decrease due to side reactions such as thermal oxidative degradation. The viscosity of the system has an important impact on the various properties of PTT. By setting appropriate polymerization temperature and reaction duration, the modified PTT polyester chips prepared not only retain their original excellent properties but also have good dyeability for cationic dyes.

[0086] Referring to Table 2 and combining Examples 3 and 7, it can be seen that when a nucleating agent is added during the preparation of the modified PTT polyester chips, the PTT tops prepared have good dyeing effects after being dyed with cationic dyes; the nucleating agent can control the crystallinity on the fiber surface and ensure stable spinning conditions and dyeing effects during the spinning process.

[0087] This specific embodiment is only an interpretation of the present application and does not limit the present application. After reading this specification, those skilled in the art can make modifications to this embodiment that do not contribute creatively as needed, but as long as it is within the scope of the claims of the present application, it is protected by the patent law.

Claims

1. A method for preparing PTT top, characterized in that: It includes the following technological steps: raw material drying → screw extrusion spinning → winding and bundling → post-treatment of tow → cutting and strip making of tow → first gilling → second gilling → balling gilling; In the said raw material drying process: drying is carried out with modified PTT polyester chips as raw materials. The preparation method of the said modified PTT polyester chips includes the following steps: S10, esterification reaction: Mix 1,3-propanediol and terephthalic acid for reaction, and at the same time add an esterification catalyst and an auxiliary agent until the esterification water discharge is completed, and end the reaction to obtain a polymerization monomer; S20, polymerization reaction: Mix the organic-inorganic hybrid microspheres with sulfonic acid groups on the surface with the said polymerization monomer, and carry out polymerization in the presence of a polymerization catalyst and a stabilizer to obtain modified PPT polyester. The obtained modified PTT polyester is pelletized to obtain PTT polyester chips; The preparation method of the said organic-inorganic hybrid microspheres is: ultrasonically mix and react silica gel particles, a silanizing reagent containing a mercapto group and toluene, remove the supernatant after centrifugation, wash and dry to obtain silica gel particles modified with silane; ultrasonically mix and react the silica gel particles modified with silane, sodium allyloxyhydroxypropyl sulfonate and an initiator, remove the supernatant after centrifugation, wash and dry; the mass ratio of the silica gel particles to the silanizing reagent containing a mercapto group is 1:(0.5 - 1); the mass ratio of the silica gel particles modified with silane to sodium allyloxyhydroxypropyl sulfonate is 1:(1 - 10); After the esterification reaction ends and before the polymerization reaction, a nucleating agent is added to the said polymerization monomer.

2. The preparation method of the PTT top according to claim 1, wherein: The said initiator is an azo initiator, including one or more of azobisisobutyronitrile, azobisisoheptonitrile, azobisisobutyramidine hydrochloride, azobisisobutyletheroxazoline hydrochloride.

3. The preparation method of the PTT top according to claim 1, characterized in that: In the said S10, the temperature during the esterification reaction is increased from 220°C to 250°C at a gradient of 3°C / 10 min.

4. The preparation method of the PTT top according to claim 1, characterized in that: In the said S10 and S20, the catalyst is one of tetrabutyl titanate, stannous octoate, antimony trioxide, antimony acetate, zinc acetate, cobalt acetate, manganese acetate, and the catalyst dosage is 0.035 - 0.055% of terephthalic acid.

5. The preparation method of the PTT top according to claim 1, characterized in that: In the said S10, the mass ratio of terephthalic acid to 1,3-propanediol is 1:(1 - 2).

6. The preparation method of the PTT top according to claim 1, characterized in that: In the said S20, the temperature during the polymerization reaction is 260 - 275°C, and the polymerization time is 300 min.

7. The preparation method of the PTT top according to claim 1, characterized in that: The said nucleating agent is one of calcium carbonate, talcum powder, barium sulfate, silicon dioxide, titanium dioxide.

8. The preparation method of the PTT top according to claim 1, characterized in that: A defoaming agent is also added while adding the said nucleating agent.

9. The preparation method of the PTT top according to claim 7, characterized in that: In the said raw material drying process, 0.05 - 0.07% of calcium stearate also needs to be added to the modified PTT polyester chip raw materials.

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