CN109722735B - Low-shrinkage polyester drawn yarn and preparation method thereof - Google Patents

Low-shrinkage polyester drawn yarn and preparation method thereof Download PDF

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CN109722735B
CN109722735B CN201811615746.8A CN201811615746A CN109722735B CN 109722735 B CN109722735 B CN 109722735B CN 201811615746 A CN201811615746 A CN 201811615746A CN 109722735 B CN109722735 B CN 109722735B
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trimethylsilyl
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CN109722735A (en
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王丽丽
王雪
孙晓华
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Jiangsu Hengli Chemical Fiber Co Ltd
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Abstract

The invention relates to a low-shrinkage polyester drawn yarn and a preparation method thereof, wherein the preparation method comprises the following steps: processing the modified polyester according to an FDY process, and adding a relaxation heat treatment process between a tension heat setting process and a winding process to obtain the low-shrinkage polyester drawn yarn; the preparation method of the modified polyester comprises the following steps: uniformly mixing terephthalic acid, ethylene glycol, dihydric alcohol with trimethylsilyl lateral group and dibasic acid with tert-butyl lateral group, and then carrying out esterification reaction and polycondensation reaction in sequence. The boiling water shrinkage rate of the prepared low-shrinkage polyester drawn yarn is 3.0 +/-0.5%, the dye uptake of the low-shrinkage polyester drawn yarn at the temperature of 125 ℃ is 86.3-89.8%, and the K/S value is 22.32-24.34. The preparation method has the advantages of simple process and low cost, and the prepared low-shrinkage polyester drawn yarn has low dyeing property and heat shrinkage.

Description

Low-shrinkage polyester drawn yarn and preparation method thereof
Technical Field
The invention belongs to the technical field of modified polyester fibers, and relates to a low-shrinkage polyester drawn yarn and a preparation method thereof.
Background
Terylene is the trade name of polyester fiber in China and is an important variety in synthetic fiber. It is made up by using refined terephthalic acid (PTA) or dimethyl terephthalate (DMT) and Ethylene Glycol (EG) as raw material, and making them pass through the processes of esterification, ester exchange and polycondensation reaction to obtain the fibre-forming high polymer-polyethylene terephthalate (PET), and making spinning and post-treatment so as to obtain the invented fibre. With the expansion of the production scale of polyester, the production technology of polyester has been greatly improved, and the production of the conventional products from the beginning is gradually developed to the production direction of high technology, functionalization, differentiation fiber and the like, and the application field of polyester fiber is gradually developed from the initial clothing fiber to the fields of decoration, industry and the like. With the continuous improvement and perfection of fiber production technology, the added value of fiber is improved, which is a necessary trend of chemical fiber development.
With the improvement of the social and economic development level and the living standard of people, people have urgent needs for high-grade and comfort of the clothing fabric. The low-shrinkage polyester filament yarn has the advantages of low shrinkage rate and good dimensional stability, can be made into fabrics with good bulkiness, drapability and hand feeling, and has very wide market prospect. The low shrinkage and dimensional stability are one direction of development of polyester fibers, and what influences the quality of the fibers is the aggregation structure of polyester macromolecules, mainly relating to the acting force among polyester molecules, the crystalline form and structure, the oriented structure and the like, and the crystalline form and structure are the key points of the polyester macromolecules. The low-shrinkage polyester yarn has good dimensional stability and heat-resistant stability, so the low-shrinkage polyester yarn has a very wide application field.
The shrinkage rate is an important performance index of the civil polyester yarn, is different from the reversible expansion and contraction phenomena of common solid substances, the chemical fiber is usually subjected to irreversible thermal shrinkage after being heated, and the shrinkage performance is more obvious when the chemical fiber is washed and ironed by hot water. The low-shrinkage civil polyester yarn has the characteristic of small shrinkage after being heated. Although the prior art can also prepare the low-shrinkage polyester civil yarns by controlling the overfeed rate and carrying out tension heat setting, the length of the fibers is fixed and can not be changed in the tension heat setting process, so that the folding of macromolecular chains is inhibited, the growth of crystal grains is limited, and the defects of crystallization exist, which can influence the heat shrinkage recovery performance (high heat shrinkage rate) of the polyester yarns.
In addition, because the terylene belongs to hydrophobic fibers, molecules of the terylene do not contain hydrophilic groups, and the molecular structure of the terylene also lacks active groups capable of being combined with dyes, the dyeing performance of the terylene fibers is poor. In addition, the finished product of the polyester fiber is a partially crystallized supermolecular structure, molecular chains of the crystallized parts of the polyester fiber are mutually parallel and mostly in a trans-conformation, while an amorphous region is mostly in a cis-conformation, and the molecular arrangement of the amorphous region is quite tight, so that the dyeing difficulty of the polyester fiber is further increased. The conventional PET fiber is dyed by adopting disperse dyes, and generally needs to be dyed at high temperature (higher than 130 ℃) and high pressure, so that the method has the disadvantages of higher requirement on equipment, high production cost and poor dyeing effect besides increasing the complexity of the process.
Therefore, the development of the low-shrinkage polyester yarn with good dyeing property and low thermal shrinkage rate has practical significance.
Disclosure of Invention
The invention aims to overcome the problems in the prior art and provide a low-shrinkage polyester drawn yarn with good dyeing property and low thermal shrinkage and a preparation method thereof.
In order to achieve the purpose, the invention adopts the technical scheme that:
the preparation method of the low-shrinkage polyester drawn yarn comprises the steps of processing modified polyester according to an FDY process, and additionally arranging a relaxation heat treatment process between a tension heat setting process and a winding process to obtain the low-shrinkage polyester drawn yarn;
the preparation method of the modified polyester comprises the following steps: uniformly mixing terephthalic acid, ethylene glycol, dihydric alcohol with trimethylsilyl lateral group and dibasic acid with tert-butyl lateral group, and then carrying out esterification reaction and polycondensation reaction in sequence;
the structural formula of the dihydric alcohol with the trimethylsilyl lateral group is as follows:
Figure BDA0001925793400000021
in the formula, R is-CH2-、-CH(CH3) -or-C ((CH)3)2)-；
The dibasic acid with tertiary butyl side group is 5-tertiary butyl-1, 3-phthalic acid, 2-tertiary butyl-1, 6-hexanedicarboxylic acid, 3-tertiary butyl-1, 6-hexanedicarboxylic acid or 2, 5-di-tertiary butyl-1, 6-hexanedicarboxylic acid;
the relaxation heat treatment refers to that the modified polyester tows pass through a space with a certain temperature in a proper relaxation state;
the proper relaxation state means that the overfeed rate of winding is 3.0-5.0%;
the certain temperature is 180-200 ℃.
The invention introduces the dihydric alcohol chain segment with the trimethylsilyl lateral group and the dibasic acid chain segment with the tertiary butyl lateral group into the molecular chain of the polyester, thereby obviously improving the dyeing property of the modified polyester, and the method specifically comprises the following steps:
the invention uses diol (3-trimethylsilyl-1, 2-propylene glycol, 3-trimethylsilyl-3-methyl-1, 2-propylene glycol or 3-trimethylsilyl-3, 3-dimethyl-1, 2-propylene glycol) with trimethylsilyl lateral group and diacid chain segment with tertiary butyl lateral group to modify polyester, the diol with trimethylsilyl lateral group and the diacid chain segment with tertiary butyl lateral group can obviously increase the space free volume of modified polyester, especially the existence of the trimethylsilyl lateral group and the diacid chain segment with tertiary butyl lateral group in the diol with trimethylsilyl lateral group can cause the change of the activity of the main chain, thereby changing the interaction force among chain units, correspondingly changing the distance among the molecular chain units and increasing the free volume of modified polyester, the increase of the free volume of the cavity can reduce the difficulty of dye molecules penetrating into the modified polyester, improve the dyeing performance of the modified polyester, reduce the dyeing temperature, shorten the dyeing time, reduce the energy consumption and improve the dye uptake of the modified polyester. The disperse dyes are dyes with small molecular weight and no water-soluble group on the structure, and are mostly in the form of particles with the particle size of hundreds of nanometers to one micron. The dye has a very low dye-uptake rate within 100 ℃, even if the dye is dyed in a boiling dye bath, the dye-uptake rate and the dye-uptake percentage are not high, when the low-shrinkage polyester drawn yarn is dyed, along with the continuous increase of the temperature, the side group in the polyester macromolecular chain starts to move before the molecular chain, when the dye bath temperature is increased to 120-130 ℃, the violent degree of the movement of the dihydric alcohol with the side group of the trimethylsilyl group and the dibasic acid chain segment with the side group of the tertiary butyl group is greater than that of the molecular chain, and when the granular dye is diffused to the inside of the fiber, the free volume of a cavity formed by the side group of the trimethylsilyl group is larger than that of a slit formed by the molecular chain, so the dye diffusion rate is higher, and the fiber dyeing performance is.
In addition, the shrinkage rate of the polyester industrial yarn is reduced by the mutual matching of the heat treatment temperature and the overfeed rate, macromolecular chains in an amorphous region of the fiber are easy to form folded chains during heat treatment, further growth of crystal grains is facilitated, the crystallinity is increased at the moment, and a certain amount of shrinkage of the fiber can be generated along with the increase of the crystallinity.
As a preferred technical scheme:
according to the preparation method of the low-shrinkage polyester drawn yarn, the space with a certain temperature is a space between a pair of parallel-arranged non-coplanar hot plates, and the hot plates are positioned between the last group of heat setting rollers and the winding rollers in the FDY equipment; the length of the two hot plates is 3.0-4.0 m along the running direction of the modified polyester tows, and the two ends of the two hot plates are flush; when the modified polyester tows pass through the middle of the two hot plates, the distance between the modified polyester tows and the two hot plates is 5-10 mm; the heat treatment method has the advantages that the energy can be obtained through macromolecular rearrangement by controlling the temperature of the hot plate (namely the certain temperature), the length of the hot plate is controlled to ensure enough crystallization time, the distance between a tow and the hot plate is controlled to ensure the heat treatment efficiency, the three are mutually cooperated, the integrity of fiber crystallization is improved, and further the thermal shrinkage in the fiber application process is reduced, wherein the temperature of the hot plate is too low, and the sufficient energy can be hardly obtained through macromolecular rearrangement; the structure formed originally can be damaged when the temperature of the hot plate is too high; the length of the hot plate is too short, the crystallization time is too short, the integrity of fiber crystallization is influenced, and the thermal shrinkage rate of the fiber is influenced; the length of the hot plate is too long, the efficiency is reduced, and equipment waste is caused; the direct contact between the tows and the hot plate is easily caused when the distance between the tows and the hot plate is too small; the thermal efficiency is reduced due to the overlarge distance between the tows and the hot plate;
the distance between the last group of heat setting rollers and the winding roller is 300-400 mm; the distance between the two hot plates and the last group of heat setting rollers is 200-300 mm.
According to the preparation method of the low-shrinkage polyester drawn yarn, the synthesis steps of the dihydric alcohol with the trimethylsilyl lateral group are as follows:
(1) mixing trimethylsilyl propylene, peracetic acid and dichloromethane according to a molar ratio of 1: 5-10: 10-15, reacting for 5-8 hours at the temperature of 35-40 ℃, stirring during the reaction, removing a solvent after the reaction is finished, and purifying and refining to obtain trimethylsilyl propylene epoxide;
(2) mixing water, concentrated sulfuric acid and trimethylsilyl propylene epoxide, heating the mixture to 80-85 ℃ in a water bath under the stirring condition, carrying out heat preservation reaction for l 0-15 min, cooling the mixture to room temperature after the reaction is finished, and carrying out neutralization, distillation, separation and purification to obtain dihydric alcohol with a trimethylsilyl lateral group, wherein the concentrated sulfuric acid is sulfuric acid with the mass concentration of 70%, the molar ratio of the trimethylsilyl propylene epoxide to the water is 1: 20-40 at the beginning of the reaction, and the mass of the concentrated sulfuric acid accounts for 0.1-0.15% of the total mass of the mixture;
the structural formula of the dihydric alcohol with the trimethylsilyl lateral groupWherein R is-CH (CH)3) -and-C ((CH)3)2) -when said trimethylsilyl propene corresponds to 3-trimethylsilyl-3-methylpropene and 3-trimethylsilyl-3, 3-dimethylpropene;
the synthesis method of the 2-tert-butyl-1, 6-hexanedicarboxylic acid, the 3-tert-butyl-1, 6-hexanedicarboxylic acid and the 2, 5-di-tert-butyl-1, 6-hexanedicarboxylic acid comprises the following steps:
firstly, mixing tungstic acid and hydrogen peroxide, stirring for 10-15 min at room temperature, then adding raw material alcohol, reacting for 1-2 h at the temperature of 80-85 ℃, then heating to 90-95 ℃ and reacting for 2-3 h, wherein reactants are always in a reflux state in the reaction process, and finally cooling, crystallizing, washing and refining;
when the reaction starts, the molar ratio of the tungstic acid to the raw material alcohol to the hydrogen peroxide is 1: 30-40: 120-150;
the raw material alcohols corresponding to the 2-tert-butyl-1, 6-hexanedicarboxylic acid, the 3-tert-butyl-1, 6-hexanedicarboxylic acid and the 2, 5-di-tert-butyl-1, 6-hexanedicarboxylic acid are respectively 2-tert-butylcyclohexanol, 4-tert-butylcyclohexanol and 2, 4-di-tert-butylcyclohexanol.
The preparation method of the low-shrinkage polyester drawn yarn comprises the following steps:
(1) performing esterification reaction;
preparing terephthalic acid, ethylene glycol, dihydric alcohol with trimethylsilyl lateral group and dibasic acid with tert-butyl lateral group into slurry, adding a catalyst, a delustering agent and a stabilizer, uniformly mixing, pressurizing in a nitrogen atmosphere to perform esterification reaction, wherein the pressurizing pressure is normal pressure to 0.3MPa, the esterification reaction temperature is 250-260 ℃, and the esterification reaction end point is determined when the water distillation amount in the esterification reaction reaches more than 90% of the theoretical value;
(2) performing polycondensation reaction;
after the esterification reaction is finished, starting the polycondensation reaction in a low vacuum stage under the condition of negative pressure, wherein the pressure in the stage is stably pumped from normal pressure to below 500Pa in 30-50 min, the reaction temperature is 250-260 ℃, the reaction time is 30-50 min, then continuously pumping vacuum to perform the polycondensation reaction in a high vacuum stage, so that the reaction pressure is further reduced to below 100Pa, the reaction temperature is 270-282 ℃, and the reaction time is 50-90 min.
According to the preparation method of the low-shrinkage polyester drawn yarn, the molar ratio of terephthalic acid to ethylene glycol is 1: 1.2-2.0, the sum of the addition amounts of the dihydric alcohol with the trimethylsilyl side group and the dibasic acid with the tert-butyl side group is 3-5 mol% (mole percentage) of the addition amount of the terephthalic acid, and the molar ratio of the dihydric alcohol with the trimethylsilyl side group to the dibasic acid with the tert-butyl side group is 1-2: 2-3; the addition amounts of the dihydric alcohol with the trimethylsilyl lateral group and the dibasic acid with the tert-butyl lateral group are not limited to the above, and the adjustment range is not too large, the excessive addition amount greatly damages the regularity of the macromolecular structure of the polyester, greatly affects the crystallinity and the mechanical property of the fiber, is not beneficial to the production and application of the fiber, and the effect is not obvious if the addition amount is too low;
the addition amounts of the catalyst, the delustering agent and the stabilizer are respectively 0.03-0.05 wt%, 0.20-0.25 wt% and 0.01-0.05 wt% (mass percentage) of the addition amount of the terephthalic acid.
According to the preparation method of the low-shrinkage polyester drawn yarn, the catalyst is antimony trioxide, ethylene glycol antimony or antimony acetate, the flatting agent is titanium dioxide, and the stabilizer is triphenyl phosphate, trimethyl phosphate or trimethyl phosphite.
According to the preparation method of the low-shrinkage polyester drawn yarn, the number average molecular weight of the modified polyester is 25000-30000, and the molecular weight distribution index is 1.8-2.2.
According to the preparation method of the low-shrinkage polyester drawn yarn, the flow of the FDY process is as follows: metering, spinneret plate extruding, cooling, oiling, stretching, heat setting and winding;
the FDY process comprises the following parameters: the spinning temperature is 285-300 ℃, the cooling temperature is 20-25 ℃, the network pressure is 0.20-0.30 MPa, the first roller speed is 2600-2800 m/min, the first roller temperature is 83-92 ℃, the two roller speed is 4200-4500 m/min, the two roller temperature is 125-145 ℃, and the winding speed is 4130-4420 m/min.
The invention also provides the low-shrinkage polyester drawn yarn prepared by the preparation method of the low-shrinkage polyester drawn yarn, which is modified polyester FDY yarn;
the molecular chain of the modified polyester comprises a terephthalic acid chain segment, an ethylene glycol chain segment, a dihydric alcohol chain segment with a trimethylsilyl lateral group and a dibasic acid chain segment with a tert-butyl lateral group.
As a preferred technical scheme:
the low-shrinkage polyester drawn yarn has the filament number of 1-2 dtex, the breaking strength of more than or equal to 4.5cN/dtex, the elongation at break of 18.0 +/-2.0 percent, the network degree of 10 +/-5 pieces/m, the linear density deviation rate of less than or equal to 1.0 percent, the CV value of the breaking strength of less than or equal to 8.0 percent and the CV value of the elongation at break of less than or equal to 8.0 percent; the low-shrinkage polyester drawn yarn prepared by the invention has other mechanical properties (except heat shrinkage) equivalent to those of common polyester products prepared by the prior art, and other mechanical properties are not reduced due to the improvement of dyeing property;
the boiling water shrinkage is 3.0 +/-0.5%; the boiling water shrinkage rate of the civil polyester yarn in the prior art is 6-10%, the size stability of the fiber is improved, and the thermal shrinkage in the application process is reduced;
the dye uptake of the low-shrinkage polyester drawn yarns at the temperature of 125 ℃ is 86.3-89.8%, the K/S value is 22.32-24.34, the soaping color fastness (polyester staining and cotton staining) reaches 5 level, the dry rubbing fastness reaches 5 level, and the wet rubbing fastness is higher than 4 level; under the same other test conditions, the dye uptake of the comparison sample at the temperature of 130 ℃ is 86.2%, the K/S value is 21.78, the soaping resistance color fastness is less than 5 grade, the polyester staining is 4-5 grade, the cotton staining is 4 grade, the dry rubbing fastness is 4-5 grade, the wet rubbing fastness is 3-4 grade, and the comparison sample is only different from the low-shrinkage polyester drawn yarn provided by the invention in that the comparison sample is made of common polyester.
The invention mechanism is as follows:
the invention obviously improves the dyeing property of the polyester by introducing the dihydric alcohol chain segment with the trimethylsilyl lateral group and the dibasic acid with the tert-butyl lateral group into the molecular chain of the polyester, and reduces the heat shrinkage rate of the polyester drawn yarn by adding the relaxation heat treatment process between the tension heat setting process and the winding process.
The mechanism of reducing the heat shrinkage is as follows:
in the post-processing and stretching process of the fiber, the fiber orientation degree is greatly increased and has certain crystallinity due to the action of mechanical stress, so that the fiber elongation and the total deformation work are reduced, but in the stretching process, although the deformation of the fiber is mostly plastic deformation which can not be recovered at normal temperature, and is often fixed due to crystallization, a part of the fiber can be recovered due to the relaxation of tensile stress at room temperature, or can be subjected to shrinkage recovery in subsequent heat treatment, the shrinkage recovery, namely the shrinkage rate of the fiber in the application process of the fiber, greatly influences the performance (such as safety performance, durability and the like) of the fiber, if the fiber is used as a tire cord, the tire cord is repeatedly stretched, compressed and bent in the use process of the tire, so that the tire is heated, the tire cord is subjected to shrinkage creep, but the blade cord can be delaminated when the cord is excessively shrunk, further, the tire is disassembled, which brings great danger to the safety of the tire.
At present, in the spinning and drawing process of polyester drawn yarns, in order to reduce the shrinkage rate of the polyester drawn yarns as much as possible, tension heat setting (a heat setting roller is adopted to set fibers under certain tension) is often required after multiple drawing, overfeeding with the overfeeding rate of 1-2% is carried out after tension heat setting, the moving capability of a polymer chain segment is improved under the conditions of certain temperature and certain tension by carrying out tension heat setting on the fibers, so that intermolecular bonding is tighter, the average size and crystallinity of crystal grains of the fibers are improved, the shrinkage rate of the fibers is reduced, but because the fibers have certain high elastic deformation in the drawing process, elastic recovery can be generated under the condition that the tension is reduced, therefore, the speed of a winding head must be lower than the speed of the last group of heat setting rollers, namely certain overfeeding rate is required, so as to ensure that the drawn yarns are shrunk under certain low tension, obtaining satisfactory finished product quality and package, preventing package edge collapse caused by overlarge tension, controlling the overfeeding rate within a certain range (1-2%), and having adverse effect on the finished product quality and the package when the overfeeding rate is overlarge. Although the shrinkage can be reduced to a certain extent by tension heat setting and overfeeding, in the tension heat setting process, the length of the fiber is fixed and can not be changed, so that the folding of macromolecular chains is inhibited, the growth rate of crystal grains is limited, the crystallization defect (the crystallinity is increased less) is caused, and the crystallization defect can not be reduced by controlling the overfeeding alone, so that when the prepared fiber is subjected to heat treatment in the application process, the macromolecular chains and chain segments of the fiber have higher mobility, the de-orientation effect is easy to generate, and the fiber is subjected to a certain amount of shrinkage (the shrinkage is larger).
In fact, the heat setting of the fibers is not only tension heat setting but also relaxation heat setting. The relaxation heat setting is also called as free shrinkage heat setting, namely, the fiber is subjected to heat treatment at a certain temperature under the condition of no tension or small tension, the fiber can be freely shrunk under the condition of the relaxation heat setting, macromolecular chains in an amorphous region easily form folding chains, and further growth of crystal grains is facilitated. At present, the relaxation heat setting is mainly used for carrying out heat setting treatment on polyester short fibers, the heat treatment temperature is low (about 130 ℃), the heat treatment time is long, and the relaxation heat setting is difficult to be suitable for filament production.
According to the invention, the overfeed rate of polyester filament bundle winding is increased to 3-5% in the processing process of the polyester drawn yarn, and meanwhile, a pair of hot plates which are arranged in parallel up and down are arranged between the last heat setting roller and the winding roller in the FDY equipment, so that the polyester filament bundle passes through the two hot plates, the crystallinity of the polyester filament bundle is improved, the high elastic deformation in the polyester filament bundle is recovered, the internal stress of the polyester filament bundle is relaxed by a certain amount, and the shrinkage recovery of the polyester drawn yarn when the polyester drawn yarn is subjected to heat treatment in the application process is reduced. The heat treatment temperature and the higher overfeed rate are matched with each other to reduce the shrinkage rate of the polyester drawn yarns, macromolecular chains in an amorphous area of the fibers are easy to form folding chains during heat treatment, further growth of crystal grains is facilitated, the crystallinity is increased at the moment, and the fibers can shrink a certain amount along with the increase of the crystallinity. In addition, the heat treatment temperature, the length of the hot plate and the distance between the tows and the hot plate are matched, so that the defect that the relaxation heat treatment in the prior art is not suitable for filament production is overcome, the completeness of fiber crystallization is improved, the stability of fiber size is improved, and the thermal shrinkage in the application process is reduced.
The mechanism for improving dyeing performance is as follows:
the macromolecular chains in the polymer are not completely tightly packed, and voids always exist among the macromolecular chains, and the void volume is the free volume. Since small molecules are allowed to penetrate into the polymer, voids are sufficiently large in the polymer or between the polymers, the permeability and diffusivity of the small molecules are related to the size of the voids (i.e., the size of free volume) in the polymer structure, and within a certain range, the larger the size of the free volume, the higher the permeability of the small molecules, and the better the diffusivity. The free volume is divided into a cavity free volume and a slit free volume, the cavity free volume has larger space size than the slit free volume, and the effect of the cavity free volume is more obvious than the effect of the slit free volume for improving the permeability of small molecules.
The size and type of free volume depends primarily on the structure of the polymer, and the primary factors affecting the polymer structure are steric hindrance, pendant group size, pendant group structure, and the like. When a certain position on the main chain of the polymer is substituted by a side group, the activity of the main chain is inevitably changed, so that the interaction force between chains is changed, the distance between the chains is also correspondingly changed, and consequently, the cohesive energy and the free volume are changed, and the polarity, the size, the length and the like of the substituent on the side chain of the polymer have certain influences on the rigidity of the molecular chain, the interaction between molecules and the free volume fraction of the polymer structure, so that the effects generated by different substituents are different, and the osmotic separation performance of the polymer is often different.
The structural formula of the diol with the trimethylsilyl lateral group is as follows:
Figure BDA0001925793400000091
in the formula, R is-CH2- (diols with trimethylsilyl side group being 3-trimethylsilyl-1, 2-propanediol), -CH (CH)3) - (diols with trimethylsilyl side groups being 3-trimethylsilyl-3-methyl-1, 2-propanediol) or-C ((CH)3)2) - (the diol having trimethylsilyl side groups is 3-trimethylsilyl-3, 3-dimethyl-1, 2-propanediol).
For ethylene glycol straight chain molecules, the C atoms on the main chain are arranged in a zigzag arrangement from top to bottom, and when the H atom on a certain methylene on the main chain is replaced by a methyl group (-CH)3) When in substitution, the C atom on the substituent group and the main chain C atom are not in the same plane, so that four sp3 hybridized orbitals on the center C are respectively overlapped with empty orbitals on the four surrounding C atoms to form four completely same sigma bonds which are arranged in a regular tetrahedron, the four carbon atoms are respectively positioned at four vertexes of the regular tetrahedron, when three hydrogen of the methyl group is further substituted by methyl or trimethylsilyl, a larger tetrahedron structure can be formed, compared with the molecular chain which is arranged in a zigzag manner, the molecular chain which is arranged in the regular tetrahedron shape has the advantages that the free volume of the empty hole is greatly increased, the permeability and the diffusivity of small molecules can be obviously improved, in addition, the bond length of the carbon-silicon bond in the trimethylsilyl group is larger than that of the carbon-carbon bond, the atom free rotation is facilitated, and the free volume of the empty hole is; when the H atom on a certain methylene on the main chain is replaced by the long branched chain substituent, the slit free volume is mainly increased, the increase amplitude is small, the improvement effect on the permeability and the diffusivity of the micromolecule is limited, and meanwhile, the long branched chain substituent has low rigidity, the molecular chains are easy to tangle, and the increase of the free volume is not facilitated.
The existence of trimethylsilyl in the diol with trimethylsilyl lateral groups can cause the change of the activity of a main chain, thereby changing the interaction force among chain units, and correspondingly changing the distance among molecular chain units, so that the free volume of the cavity of the modified polyester is increased. Compared with short-branched-chain substituent groups (such as methyl groups, ethyl groups and the like), the trimethylsilyl group occupies a larger spatial position, and a larger free volume is obtained in the molecular chain arrangement mode; compared with the long-branched-chain substituent, on one hand, the increased free volume of the trimethylsilyl group is more hollow free volume, while the increased free volume of the long-branched-chain substituent is more slit free volume, and on the other hand, the rigidity of the trimethylsilyl group is higher than that of the long-branched-chain substituent, so that the entanglement among molecular chains is reduced, and therefore, the longer-branched-chain substituent of the trimethylsilyl group has more free volume in the molecular chain arrangement mode. The introduction of the diol with trimethylsilyl lateral groups increases the spatial free volume of the modified polyester, and particularly the increase of the free volume of a cavity is more obvious.
For straight chain molecules such as isophthalic acid and adipic acid, when the H atom on the benzene ring of isophthalic acid or the H atom on the methylene group of adipic acid is replaced by a methyl group (-CH)3) When in substitution, the C atoms on the side groups and the main chain C atoms are not in the same plane, so that four sp3 hybridized orbitals on the center C are respectively overlapped with empty orbitals on the four surrounding C atoms to form four completely same sigma bonds which are arranged in a regular tetrahedron, the four carbon atoms are respectively positioned at four vertexes of the regular tetrahedron, when three hydrogen of a methyl group is further substituted by the methyl group, the three hydrogen is equivalent to tert-butyl to be substituted to form a larger tetrahedron structure, molecular chains arranged in the regular tetrahedron are relatively arranged in a zigzag manner, the free volume of the empty holes is obviously increased by a lot, and the permeability and diffusivity of small molecules can be obviously improved; when the H atom on the benzene ring of the isophthalic acid or the H atom on the methylene of the adipic acid is replaced by the long branched chain substituent, the slit free volume is mainly increased, the increase amplitude is small, the improvement effect on the permeability and the diffusivity of the small molecule is limited, and meanwhile, the long branched chain substituent has small rigidity, the molecular chains are easy to tangle, and the increase of the free volume is not facilitated.
The dibasic acid with the tertiary butyl side group is 5-tertiary butyl-1, 3-phthalic acid, 2-tertiary butyl-1, 6-adipic acid, 3-tertiary butyl-1, 6-adipic acid or 2, 5-di-tertiary butyl-1, 6-adipic acid, wherein the 2-tertiary butyl-1, 6-adipic acid, 3-tertiary butyl-1, 6-adipic acid and 2, 5-di-tertiary butyl-1, 6-adipic acid are adipic acid, and the adipic acid is fatty acid, the rigidity of the fatty acid is less than that of the 5-tertiary butyl-1, 3-phthalic acid, which is beneficial to improving the softness of a polyester chain segment, and the existence of the tertiary butyl in the dibasic acid with the tertiary butyl side group can cause the change of the activity of a main chain so as to change the interaction force among chain units, the distance between molecular chain units is also changed correspondingly, which leads to the increase of the free volume of the hollow of the modified polyester. Compared with short-chain substituent groups (such as methyl, ethyl and the like), the tertiary butyl group occupies a larger spatial position, and a larger free volume is obtained in the molecular chain arrangement mode; compared with the long-branched-chain substituent, on one hand, the tertiary butyl group has the increased free volume of a cavity, the long-branched-chain substituent has the increased free volume of a slit, and on the other hand, the rigidity of the tertiary butyl group is higher than that of the long-branched-chain substituent, so that entanglement among molecular chains is reduced, and the tertiary butyl group has more free volume than the long-branched-chain substituent in the arrangement mode of the molecular chains. In addition, when the dibasic acid with the tertiary butyl side group is 5-tertiary butyl-1, 3-phthalic acid, a benzene ring connected with the m-phthalic acid forms a larger asymmetric chain segment, so that the steric hindrance of inter-chain-segment migration is increased, the steric hindrance of rotation around a m-connection bond in the chain segment is increased, the introduction of the m-isomer is favorable for increasing the free volume, and the introduction of the dibasic acid with the tertiary butyl side group also increases the free volume of a cavity of the modified polyester.
The increase of the free volume of the cavity enables water or other molecules such as dye to be easier to permeate into the modified polyester macromolecules, has positive influence on the dyeing of the modified polyester and the like, can reduce the dyeing temperature and the energy consumption, and simultaneously improves the dye uptake of the fiber during dyeing.
Has the advantages that:
(1) according to the preparation method of the low-shrinkage polyester drawn yarn, the heat treatment temperature is matched with the higher overfeed rate, so that the integrity of fiber crystallization is improved, and the thermal shrinkage in the application process is reduced;
(2) according to the preparation method of the low-shrinkage polyester drawn yarn, the dibasic acid with the tert-butyl side group and the dihydric alcohol with the trimethylsilyl side group are introduced into the polyester to modify the polyester, so that the dyeing temperature is reduced, the dyeing time is shortened, the dye-uptake of the fiber is improved, the energy consumption is reduced, and the spinnability is improved;
(3) the low-shrinkage polyester drawn yarn disclosed by the invention is excellent in dyeing performance, excellent in mechanical performance and good in application prospect.
Detailed Description
The invention will be further illustrated with reference to specific embodiments. It should be understood that these examples are for illustrative purposes only and are not intended to limit the scope of the present invention. Further, it should be understood that various changes or modifications of the present invention may be made by those skilled in the art after reading the teaching of the present invention, and such equivalents may fall within the scope of the present invention as defined in the appended claims.
Figure BDA0001925793400000111
Example 1
The preparation method of the low-shrinkage polyester drawn yarn comprises the following steps:
(1) preparing modified polyester;
(1.1) esterification reaction;
preparing terephthalic acid, ethylene glycol, 3-trimethylsilyl-1, 2-propanediol and 5-tert-butyl-1, 3-phthalic acid into slurry, adding antimony trioxide, titanium dioxide and triphenyl phosphate, uniformly mixing, pressurizing in a nitrogen atmosphere to perform esterification reaction, wherein the pressurizing pressure is normal pressure, the esterification reaction temperature is 250 ℃, and the esterification reaction end point is determined when the distilled water amount in the esterification reaction reaches 91% of a theoretical value, wherein the molar ratio of the terephthalic acid to the ethylene glycol is 1:2.1, the sum of the added amounts of the 3-trimethylsilyl-1, 2-propanediol and the 5-tert-butyl-1, 3-phthalic acid is 4 mol% of the added amount of the terephthalic acid, and the added amounts of the 3-trimethylsilyl-1, 2-propanediol and the 5-tert-butyl-1, the molar ratio of the 3-phthalic acid is 1:3, and the addition amounts of the antimony trioxide, the titanium dioxide and the triphenyl phosphate are respectively 0.03 wt%, 0.20 wt% and 0.04 wt% of the addition amount of the terephthalic acid;
(1.2) polycondensation reaction;
after the esterification reaction is finished, starting the polycondensation reaction in a low vacuum stage under the condition of negative pressure, stably pumping the pressure in the stage from normal pressure to the absolute pressure of 500Pa within 30min, controlling the reaction temperature to be 255 ℃ and the reaction time to be 30min, then continuing to pump vacuum, and carrying out the polycondensation reaction in a high vacuum stage to further reduce the reaction pressure to the absolute pressure of 100Pa, control the reaction temperature to be 270 ℃ and control the reaction time to be 40min, wherein the number average molecular weight of the prepared modified polyester is 25000 and the molecular weight distribution index is 1.8;
(2) preparing low-shrinkage polyester drawn yarns;
processing the modified polyester according to an FDY process to obtain the low-shrinkage polyester drawn yarn, wherein the FDY process comprises the following steps: metering, spinneret plate extruding, cooling, oiling, stretching, heat setting, relaxation heat treatment and winding, wherein the relaxation heat treatment refers to that polyester filament bundles with 4.9% of winding overfeed rate pass through a space between a pair of hot plates which are arranged in parallel and are not coplanar and have the temperature of 200 ℃, the hot plates are positioned between the last group of heat setting rollers and the winding rollers in the FDY equipment, the length of the two hot plates is 3.0m along the running direction of the polyester filament bundles, the two ends of the two hot plates are flush, the distance between the polyester filament bundles and the two hot plates is 5mm when the polyester filament bundles pass through the middle of the two hot plates, the distance between the last group of heat setting rollers and the winding rollers is 300mm, and the distance between the two hot plates and the last group of heat setting rollers is 200 mm;
the parameters of the FDY process are as follows: the spinning temperature is 285 ℃, the cooling temperature is 20 ℃, the network pressure is 0.23MPa, the one-roller speed is 2800m/min, the one-roller temperature is 88 ℃, the two-roller speed is 4200m/min, the two-roller temperature is 125 ℃, and the winding speed is 4220 m/min.
The finally prepared low-shrinkage polyester drawn yarn is modified polyester FDY yarn, the filament number of the low-shrinkage polyester drawn yarn is 2dtex, the breaking strength is 4.8cN/dtex, the elongation at break is 18.0 percent, the network degree is 12/m, the linear density deviation rate is 0.95 percent, the CV value of the breaking strength is 7.8 percent, the CV value of the elongation at break is 8.0 percent, and the shrinkage in boiling water is 3.5 percent;
the dye uptake of the low-shrinkage polyester drawn yarn at the temperature of 125 ℃ is 88.6 percent, the K/S value is 24.34, the soaping-resistant color fastness reaches 5 grade, the dry rubbing fastness reaches 5 grade, and the wet rubbing fastness reaches 6 grade.
Comparative example 1
A preparation method of low-shrinkage polyester drawn yarn, its step is basically the same as example 1, the difference lies in, step (1) does not add 3-trimethylsilyl-1, 2-propanediol and 5-tert-butyl-1, 3-phthalic acid, namely modify polyester, the monofilament number of low-shrinkage polyester drawn yarn that it makes is 2.0dtex, breaking strength is 4.5cN/dtex, elongation at break is 19.0%, the network degree is 12/m, the linear density deviation rate is 1.00%, the breaking strength CV value is 7.7%, the elongation at break CV value is 8.0%, the boiling water shrinkage factor is 3.5%; under the same conditions as other testing conditions in example 1, the dye uptake rate of the polyester is 84.7% under the temperature condition of 130 ℃, the K/S value is 21.58, the soaping fastness is less than grade 5, the polyester staining is grade 4-5, the cotton staining is grade 4, the dry rubbing fastness is grade 4-5, and the wet rubbing fastness is grade 3-4.
Compared with the example 1, the invention can find that the dyeing property of the fiber is obviously improved by adding the 3-trimethylsilyl-1, 2-propanediol and the 5-tert-butyl-1, 3-phthalic acid, and the addition of the 3-trimethylsilyl-1, 2-propanediol and the 5-tert-butyl-1, 3-phthalic acid has little influence on other properties of the fiber and does not influence the processing property and the mechanical property of the fiber.
Comparative example 2
A preparation method of low shrinkage type polyester drawn yarn, its step is basically the same as example 1, the difference lies in, step (1) uses 1,2 dodecyl glycol to replace 3-trimethylsilyl-1, 2-propanediol and 5-tert-butyl-1, 3-phthalic acid, the filament number of the low shrinkage type polyester drawn yarn made is 2.0dtex, breaking strength is 4.6cN/dtex, elongation at break is 18.0%, the network degree is 12/m, the linear density deviation rate is 1.00%, the breaking strength CV value is 7.6%, the elongation at break CV value is 8.0%, the boiling water shrinkage factor is 3.5%; under the same conditions as other testing conditions in example 1, the dye uptake rate of the polyester is 85.6% under the temperature condition of 130 ℃, the K/S value is 21.67, the soaping fastness is less than grade 5, the polyester staining is grade 4-5, the cotton staining is grade 4, the dry rubbing fastness is grade 4-5, and the wet rubbing fastness is grade 3-4.
In comparison with example 1, it can be seen that the diacid with tertiary butyl side groups (5-tertiary butyl-1, 3-phthalic acid) and the diol with trimethylsilyl side groups (3-trimethylsilyl-1, 2-propanediol) are more advantageous for improving the dyeing properties of the fibers than the 1, 2-dodecyldiol with a long branched substituent, mainly because the diacid with tertiary butyl side groups and the diol with trimethylsilyl side groups on one hand have a free volume which is increased more by the tertiary butyl group and is a hollow free volume, while the diol with a long branched substituent has a free volume which is increased more by the long branched substituent and on the other hand the diacid with tertiary butyl side groups has a rigidity which is greater than that of the long branched chain, reducing entanglement between the molecular chains, so that the diacid with tertiary butyl side groups has more favorable dyeing properties than the 1, the 2-dodecyl glycol has more free volume in the molecular chain arrangement mode, thereby being more beneficial to improving the dyeing property of the fiber.
Comparative example 3
A preparation method of a low shrinkage type polyester drawn yarn, which is basically the same as the example 1, and is characterized in that the step (2) does not include a relaxation heat treatment process, the winding speed is 2680m/min, the winding overfeed rate is 1.47%, the filament number of the finally prepared low shrinkage type polyester drawn yarn is 2.0dtex, the breaking strength is 4.3cN/dtex, the elongation at break is 22.0%, the network degree is 12/m, the linear density deviation rate is 1.10%, the breaking strength CV value is 7.9%, the elongation at break CV value is 8.0%, and the boiling water shrinkage rate is 5.5%; under the same conditions as other testing conditions in example 1, the dye uptake rate of the polyester is 88.3% under the temperature condition of 130 ℃, the K/S value is 23.87, the soaping fastness is less than grade 5, the polyester staining is grade 4-5, the cotton staining is grade 4, the dry rubbing fastness is grade 4-5, and the wet rubbing fastness is grade 3-4. Comparing example 1 with comparative example 3, it can be seen that the shrinkage rate of the low-shrinkage polyester drawn yarn is significantly reduced by adding the relaxation heat treatment process.
Example 2
The preparation method of the low-shrinkage polyester drawn yarn comprises the following steps:
(1) preparing modified polyester;
(1.1) preparation of 2-tert-butyl-1, 6-hexanedicarboxylic acid: firstly, mixing tungstic acid and hydrogen peroxide, stirring for 10min at room temperature, then adding 2-tert-butylcyclohexanol, reacting for 1h at the temperature of 80 ℃, heating to 94 ℃ for reaction for 2h, wherein reactants are always in a reflux state in the reaction process, and finally cooling, crystallizing, washing and refining, wherein the molar ratio of the tungstic acid to the 2-tert-butylcyclohexanol to the hydrogen peroxide is 1:35:120 at the beginning of the reaction;
(1.2) esterification reaction;
preparing terephthalic acid, ethylene glycol, 3-trimethylsilyl-1, 2-propanediol and 2-tert-butyl-1, 6-hexanedioic acid into slurry, adding antimony trioxide, titanium dioxide and trimethyl phosphite, uniformly mixing, pressurizing in a nitrogen atmosphere to perform esterification reaction, wherein the pressurizing pressure is 0.3MPa, the esterification reaction temperature is 260 ℃, and the esterification reaction end point is determined when the distilled water amount in the esterification reaction reaches 92% of a theoretical value, wherein the molar ratio of the terephthalic acid to the ethylene glycol is 1:2.0, the sum of the adding amounts of the 3-trimethylsilyl-1, 2-propanediol and the 2-tert-butyl-1, 6-hexanedioic acid is 3 mol% of the adding amount of the terephthalic acid, and the adding amounts of the 3-trimethylsilyl-1, 2-propanediol and the 2-tert-butyl-1, the molar ratio of 6-hexanedicarboxylic acid is 2:2, and the addition amounts of antimony trioxide, titanium dioxide and trimethyl phosphite are 0.04 wt%, 0.25wt% and 0.01 wt% of the addition amount of terephthalic acid respectively;
(1.3) a polycondensation reaction;
after the esterification reaction is finished, starting the polycondensation reaction in the low vacuum stage under the negative pressure condition, stably pumping the pressure in the stage from normal pressure to absolute pressure of 400Pa within 40min, controlling the reaction temperature to 272 ℃, controlling the reaction time to 40min, then continuing to pump vacuum, and carrying out the polycondensation reaction in the high vacuum stage, so that the reaction pressure is further reduced to absolute pressure of 80Pa, the reaction temperature is 272 ℃, the reaction time is 65min, and the number average molecular weight of the prepared modified polyester is 28000 and the molecular weight distribution index is 1.8;
(2) preparing low-shrinkage polyester drawn yarns;
processing the modified polyester according to an FDY process to obtain the low-shrinkage polyester drawn yarn, wherein the FDY process comprises the following steps: metering, spinneret plate extruding, cooling, oiling, stretching, heat setting, relaxation heat treatment and winding, wherein the relaxation heat treatment refers to that polyester filament bundles with 4.2% of winding overfeed rate pass through a space between a pair of hot plates which are arranged in parallel and are not coplanar and have the temperature of 207 ℃, the hot plates are positioned between the last group of heat setting rollers and the winding rollers in the FDY equipment, the length of the two hot plates is 3.2m along the running direction of the polyester filament bundles, the two ends of the two hot plates are flush, the distance between the polyester filament bundles and the two hot plates is 6mm when the polyester filament bundles pass through the middle of the two hot plates, the distance between the last group of heat setting rollers and the winding rollers is 311mm, and the distance between the two hot plates and the last group of heat setting rollers is 220 mm;
the parameters of the FDY process are as follows: the spinning temperature is 285 ℃, the cooling temperature is 25 ℃, the network pressure is 0.20MPa, the first roller speed is 2700m/min, the first roller temperature is 90 ℃, the two roller speed is 4500m/min, the two roller temperature is 145 ℃, and the winding speed is 4130 m/min.
The finally prepared low-shrinkage polyester drawn yarn is modified polyester FDY yarn, the filament number of the low-shrinkage polyester drawn yarn is 1.5dtex, the breaking strength is 4.5cN/dtex, the elongation at break is 18.0 percent, the network degree is 5/m, the linear density deviation rate is 0.96 percent, the CV value of the breaking strength is 7.2 percent, the CV value of the elongation at break is 7.6 percent, and the shrinkage in boiling water is 3.5 percent;
the dye uptake of the low-shrinkage polyester drawn yarn at the temperature of 125 ℃ is 86.3 percent, the K/S value is 23.65, the soaping-resistant color fastness reaches 5 grade, the dry rubbing fastness reaches 5 grade, and the wet rubbing fastness reaches 6 grade.
Example 3
The preparation method of the low-shrinkage polyester drawn yarn comprises the following steps:
(1) preparing modified polyester;
(1.1) preparation of 2-tert-butyl-1, 6-hexanedicarboxylic acid: firstly, mixing tungstic acid and hydrogen peroxide, stirring for 12min at room temperature, then adding 2-tert-butylcyclohexanol, reacting for 1.5h at 83 ℃, then heating to 90 ℃ for reacting for 2h, wherein reactants are always in a reflux state in the reaction process, and finally cooling, crystallizing, washing and refining, wherein the molar ratio of tungstic acid, 2-tert-butylcyclohexanol and hydrogen peroxide is 1:33:120 at the beginning of the reaction;
(1.2) preparing dihydric alcohol with trimethylsilyl lateral groups;
(a) mixing 3-trimethylsilyl-3-methylpropene, peracetic acid and dichloromethane according to a molar ratio of 1:5:10, reacting for 5 hours at the temperature of 35 ℃, stirring during the reaction, removing a solvent after the reaction is finished, and purifying and refining to obtain trimethylsilyl propylene epoxide;
(b) mixing water, concentrated sulfuric acid and trimethylsilyl propylene epoxide, heating to 80 ℃ in water bath under stirring, carrying out heat preservation reaction for 10min, cooling to room temperature after the reaction is finished, and carrying out neutralization, distillation, separation and purification to obtain the diol with the trimethylsilyl side group shown in the formula (I), wherein R in the formula (I) is-CH (CH)3) The concentrated sulfuric acid is sulfuric acid with the mass concentration of 70%, the molar ratio of the trimethylsilyl propylene epoxide to water is 1:20 when the reaction starts, and the mass of the concentrated sulfuric acid accounts for 0.1% of the mass sum of the mixture;
(1.3) esterification reaction;
preparing terephthalic acid, ethylene glycol, diol with trimethylsilyl groups and 2-tert-butyl-1, 6-hexanedicarboxylic acid into slurry, adding ethylene glycol antimony, titanium dioxide and triphenyl phosphate, uniformly mixing, pressurizing in a nitrogen atmosphere to perform esterification reaction, wherein the pressurizing pressure is 0.2MPa, the esterification reaction temperature is 255 ℃, the esterification reaction endpoint is determined when the water distillation amount in the esterification reaction reaches 90% of a theoretical value, the molar ratio of the terephthalic acid to the ethylene glycol is 1:1.2, the sum of the addition amounts of the diol with trimethylsilyl groups and the 2-tert-butyl-1, 6-hexanedicarboxylic acid is 3 mol% of the addition amount of the terephthalic acid, the molar ratio of the diol with trimethylsilyl groups and the 2-tert-butyl-1, 6-hexanedicarboxylic acid is 1:2.4, and the addition amounts of the ethylene glycol antimony, the titanium dioxide and the triphenyl phosphate are respectively 0.04 wt% of the addition amount of the terephthalic acid, 0.22 wt% and 0.05 wt%;
(1.4) a polycondensation reaction;
after the esterification reaction is finished, starting the polycondensation reaction in a low vacuum stage under the negative pressure condition, wherein the pressure in the stage is stably pumped from normal pressure to the absolute pressure of 450Pa within 45min, the reaction temperature is 276 ℃, the reaction time is 50min, then continuing to pump vacuum, and carrying out the polycondensation reaction in a high vacuum stage, so that the reaction pressure is further reduced to the absolute pressure of 100Pa, the reaction temperature is 275 ℃, the reaction time is 60min, and the number average molecular weight of the prepared modified polyester is 25000 and the molecular weight distribution index is 2.0;
(2) preparing low-shrinkage polyester drawn yarns;
processing the modified polyester according to an FDY process to obtain the low-shrinkage polyester drawn yarn, wherein the FDY process comprises the following steps: metering, spinneret extrusion, cooling, oiling, stretching, heat setting, relaxation heat treatment and winding, wherein the relaxation heat treatment refers to that polyester filament bundles with 3.3% of winding overfeed rate pass through a space between a pair of hot plates which are arranged in parallel and are not coplanar and have the temperature of 215 ℃, the hot plates are positioned between the last group of heat setting rollers and the winding rollers in the FDY equipment, the length of the two hot plates is 3.3m along the running direction of the polyester filament bundles, the two ends of the two hot plates are flush, the distance between the polyester filament bundles and the two hot plates is 7mm when the polyester filament bundles pass through the middle of the two hot plates, the distance between the last group of heat setting rollers and the winding rollers is 335mm, and the distance between the two hot plates and the last group of heat setting rollers is 235 mm;
the parameters of the FDY process are as follows: the spinning temperature is 290 ℃, the cooling temperature is 20 ℃, the network pressure is 0.20MPa, the speed of one roller is 2600m/min, the temperature of one roller is 92 ℃, the speed of two rollers is 4300m/min, the temperature of two rollers is 125 ℃, and the winding speed is 4130 m/min.
The finally prepared low-shrinkage polyester drawn yarn is modified polyester FDY yarn, the filament number of the low-shrinkage polyester drawn yarn is 1dtex, the breaking strength is 4.5cN/dtex, the elongation at break is 20.0 percent, the network degree is 10/m, the linear density deviation rate is 0.97 percent, the CV value of the breaking strength is 7.6 percent, the CV value of the elongation at break is 8.0 percent, and the shrinkage in boiling water is 2.5 percent;
the dye uptake of the low-shrinkage polyester drawn yarn at the temperature of 125 ℃ is 86.3 percent, the K/S value is 22.32, the soaping-resistant color fastness reaches 5 grade, the dry rubbing fastness reaches 5 grade, and the wet rubbing fastness reaches 5 grade.
Example 4
The preparation method of the low-shrinkage polyester drawn yarn comprises the following steps:
(1) preparing modified polyester;
(1.1) preparation of 3-tert-butyl-1, 6-hexanedicarboxylic acid: firstly, mixing tungstic acid and hydrogen peroxide, stirring for 13min at room temperature, then adding 4-tert-butylcyclohexanol, reacting for 2h at the temperature of 85 ℃, heating to 90 ℃ and reacting for 3h, wherein reactants are always in a reflux state in the reaction process, and finally cooling, crystallizing, washing and refining, wherein the molar ratio of the tungstic acid to the 4-tert-butylcyclohexanol to the hydrogen peroxide is 1:30:130 at the beginning of the reaction;
(1.2) preparing dihydric alcohol with trimethylsilyl lateral groups;
(a) mixing 3-trimethylsilyl-3-methylpropene, peracetic acid and dichloromethane according to the molar ratio of 1:10:15, reacting for 8 hours at the temperature of 40 ℃, stirring during the reaction, removing the solvent after the reaction is finished, and purifying and refining to obtain trimethylsilyl propylene epoxide;
(b) mixing water, concentrated sulfuric acid and trimethylsilyl propylene epoxide, heating to 85 ℃ in water bath under stirring, carrying out heat preservation reaction for 15min, cooling to room temperature after the reaction is finished, and carrying out neutralization, distillation, separation and purification to obtain the diol with the trimethylsilyl side group shown in the formula (I), wherein R in the formula (I) is-CH (CH)3) The concentrated sulfuric acid is sulfuric acid with the mass concentration of 70%, the molar ratio of the trimethylsilyl propylene epoxide to water is 1:40 when the reaction starts, and the mass of the concentrated sulfuric acid accounts for 0.15% of the mass sum of the mixture;
(1.3) esterification reaction;
preparing terephthalic acid, ethylene glycol, diol with trimethylsilyl groups and 3-tert-butyl-1, 6-hexanedicarboxylic acid into slurry, adding ethylene glycol antimony, titanium dioxide and trimethyl phosphite, uniformly mixing, pressurizing in a nitrogen atmosphere to perform esterification reaction, wherein the pressurizing pressure is 0.1MPa, the esterification reaction temperature is 250 ℃, the esterification reaction endpoint is determined when the distilled water amount in the esterification reaction reaches 90% of a theoretical value, the molar ratio of the terephthalic acid to the ethylene glycol is 1:1.5, the sum of the adding amounts of the diol with trimethylsilyl groups and the 3-tert-butyl-1, 6-hexanedicarboxylic acid is 5mol% of the adding amount of the terephthalic acid, the molar ratio of the diol with trimethylsilyl groups and the 3-tert-butyl-1, 6-hexanedicarboxylic acid is 1.6:2.8, and the adding amounts of the ethylene glycol antimony, the titanium dioxide and the trimethyl phosphite are respectively 0.05wt% of the adding amount of the terephthalic acid, 0.20 wt% and 0.03 wt%;
(1.4) a polycondensation reaction;
after the esterification reaction is finished, starting the polycondensation reaction in the low vacuum stage under the negative pressure condition, stably pumping the pressure in the stage from normal pressure to absolute pressure of 420Pa within 50min, controlling the reaction temperature to be 280 ℃ and the reaction time to be 80min, then continuing to pump vacuum, and carrying out the polycondensation reaction in the high vacuum stage, so that the reaction pressure is further reduced to absolute pressure of 85Pa, the reaction temperature is 270 ℃ and the reaction time is 40min, wherein the number average molecular weight of the prepared modified polyester is 29000 and the molecular weight distribution index is 2.2;
(2) preparing low-shrinkage polyester drawn yarns;
processing the modified polyester according to an FDY process to obtain the low-shrinkage polyester drawn yarn, wherein the FDY process comprises the following steps: metering, spinneret extrusion, cooling, oiling, stretching, heat setting, relaxation heat treatment and winding, wherein the relaxation heat treatment refers to that polyester filament bundles with the winding overfeed rate of 4.8% pass through a space between a pair of hot plates which are arranged in parallel and are not coplanar and have the temperature of 222 ℃, the hot plates are positioned between the last group of heat setting rollers and the winding rollers in the FDY equipment, the length of the two hot plates is 3.4m along the running direction of the polyester filament bundles, the two ends of the two hot plates are flush, the distance between the polyester filament bundles and the two hot plates is 8mm when the polyester filament bundles pass through the middle of the two hot plates, the distance between the last group of heat setting rollers and the winding rollers is 346mm, and the distance between the two hot plates and the last group of heat setting rollers is 250 mm;
the parameters of the FDY process are as follows: the spinning temperature is 290 ℃, the cooling temperature is 22 ℃, the network pressure is 0.30MPa, the speed of one roller is 2600m/min, the temperature of one roller is 83 ℃, the speed of two rollers is 4300m/min, the temperature of two rollers is 130 ℃, and the winding speed is 4420 m/min.
The finally prepared low-shrinkage polyester drawn yarn is modified polyester FDY yarn, the filament number of the low-shrinkage polyester drawn yarn is 1dtex, the breaking strength is 4.44cN/dtex, the elongation at break is 16.0 percent, the network degree is 15/m, the linear density deviation rate is 1.0 percent, the CV value of the breaking strength is 7.6 percent, the CV value of the elongation at break is 7.9 percent, and the shrinkage in boiling water is 3.0 percent;
the dye uptake of the low-shrinkage polyester drawn yarn at the temperature of 125 ℃ is 89.8 percent, the K/S value is 22.32, the soaping-resistant color fastness reaches 5 grade, the dry rubbing fastness reaches 5 grade, and the wet rubbing fastness reaches 5 grade.
Example 5
The preparation method of the low-shrinkage polyester drawn yarn comprises the following steps:
(1) preparing modified polyester;
(1.1) preparation of 3-tert-butyl-1, 6-hexanedicarboxylic acid: firstly, mixing tungstic acid and hydrogen peroxide, stirring for 14min at room temperature, then adding 4-tert-butylcyclohexanol, reacting for 2h at the temperature of 82 ℃, then heating to 92 ℃ for reacting for 3h, wherein reactants are always in a reflux state in the reaction process, and finally cooling, crystallizing, washing and refining, wherein the molar ratio of the tungstic acid to the 4-tert-butylcyclohexanol to the hydrogen peroxide is 1:40:130 at the beginning of the reaction;
(1.2) preparing dihydric alcohol with trimethylsilyl lateral groups;
(a) mixing 3-trimethylsilyl-3-methylpropene, peracetic acid and dichloromethane according to a molar ratio of 1:10:10, reacting for 6 hours at the temperature of 36 ℃, stirring during the reaction, removing a solvent after the reaction is finished, and purifying and refining to obtain trimethylsilyl propylene epoxide;
(b) mixing water, concentrated sulfuric acid and trimethylsilyl propylene epoxide, heating to 84 ℃ in water bath under stirring, preserving heat for reaction for 12min, cooling to room temperature after the reaction is finished, and obtaining the dihydric alcohol with the trimethylsilyl lateral group shown in the formula (I) through neutralization, distillation, separation and purification, wherein R in the formula (I) is-CH (CH)3) The concentrated sulfuric acid is sulfuric acid with the mass concentration of 70%, the molar ratio of the trimethylsilyl propylene epoxide to water is 1:30 when the reaction starts, and the mass of the concentrated sulfuric acid accounts for 0.14% of the mass sum of the mixture;
(1.3) esterification reaction;
preparing terephthalic acid, ethylene glycol, diol with trimethylsilyl groups and 3-tert-butyl-1, 6-hexanedicarboxylic acid into slurry, adding antimony acetate, titanium dioxide and trimethyl phosphate, uniformly mixing, pressurizing in a nitrogen atmosphere to perform esterification reaction, wherein the pressurizing pressure is 0.3MPa, the esterification reaction temperature is 252 ℃, the esterification reaction end point is reached when the water distillation amount in the esterification reaction reaches 90% of a theoretical value, the molar ratio of the terephthalic acid to the ethylene glycol is 1:1.8, the sum of the addition amounts of the diol with trimethylsilyl groups and the 3-tert-butyl-1, 6-hexanedicarboxylic acid is 4 mol% of the addition amount of the terephthalic acid, the molar ratio of the diol with trimethylsilyl groups and the 3-tert-butyl-1, 6-hexanedicarboxylic acid is 1.2:2, and the addition amounts of the antimony acetate, the titanium dioxide and the trimethyl phosphate are respectively 0.03 wt% of the addition amount of the terephthalic acid, 0.24 wt% and 0.04 wt%;
(1.4) a polycondensation reaction;
after the esterification reaction is finished, starting the polycondensation reaction in a low vacuum stage under the condition of negative pressure, smoothly pumping the pressure in the stage from normal pressure to absolute pressure of 500Pa within 30min, controlling the reaction temperature to 282 ℃ and the reaction time to 80min, then continuing to pump vacuum, and carrying out the polycondensation reaction in a high vacuum stage to further reduce the reaction pressure to absolute pressure of 88Pa, control the reaction temperature to 272 ℃ and control the reaction time to 75min, wherein the number average molecular weight of the prepared modified polyester is 30000 and the molecular weight distribution index is 1.9;
(2) preparing low-shrinkage polyester drawn yarns;
processing the modified polyester according to an FDY process to obtain the low-shrinkage polyester drawn yarn, wherein the FDY process comprises the following steps: metering, spinneret plate extruding, cooling, oiling, stretching, heat setting, relaxation heat treatment and winding, wherein the relaxation heat treatment refers to that polyester filament bundles with the winding overfeed rate of 4.0% pass through a space between a pair of hot plates which are arranged in parallel and are not coplanar and have the temperature of 232 ℃, the hot plates are positioned between the last group of heat setting rollers and the winding rollers in the FDY equipment, the length of the two hot plates is 3.6m along the running direction of the polyester filament bundles, the two ends of the two hot plates are flush, the distance between the polyester filament bundles and the two hot plates is 8.5mm when the polyester filament bundles pass through the middle of the two hot plates, the distance between the last group of heat setting rollers and the winding rollers is 368mm, and the distance between the two hot plates and the last group of heat setting rollers is 260 mm;
the parameters of the FDY process are as follows: the spinning temperature is 300 ℃, the cooling temperature is 21 ℃, the network pressure is 0.28MPa, the one-roll speed is 2800m/min, the one-roll temperature is 83 ℃, the two-roll speed is 4200m/min, the two-roll temperature is 135 ℃, and the winding speed is 4350 m/min.
The finally prepared low-shrinkage polyester drawn yarn is modified polyester FDY yarn, the filament number of the low-shrinkage polyester drawn yarn is 2dtex, the breaking strength is 4.6cN/dtex, the elongation at break is 18.0 percent, the network degree is 10/m, the linear density deviation rate is 0.95 percent, the CV value of the breaking strength is 8.0 percent, the CV value of the elongation at break is 8.0 percent, and the shrinkage in boiling water is 3.2 percent;
the dye uptake of the low-shrinkage polyester drawn yarn at the temperature of 125 ℃ is 87.38%, the K/S value is 24.34, the soaping-resistant color fastness reaches 5 grade, the dry rubbing fastness reaches 5 grade, and the wet rubbing fastness reaches 5 grade.
Example 6
The preparation method of the low-shrinkage polyester drawn yarn comprises the following steps:
(1) preparing modified polyester;
(1.1) preparation of 2, 5-di-tert-butyl-1, 6-hexanedicarboxylic acid: firstly, mixing tungstic acid and hydrogen peroxide, stirring for 15min at room temperature, then adding 2, 4-di-tert-butylcyclohexanol, reacting for 1.5h at 83 ℃, then heating to 92 ℃ and reacting for 2.5h, wherein reactants are always in a reflux state in the reaction process, and finally cooling, crystallizing, washing and refining, wherein the molar ratio of the tungstic acid to the 2, 4-di-tert-butylcyclohexanol to the hydrogen peroxide is 1:40:120 when the reaction starts;
(1.2) preparing dihydric alcohol with trimethylsilyl lateral groups;
(a) mixing 3-trimethylsilyl-3, 3-dimethylpropene, peracetic acid and dichloromethane according to the molar ratio of 1:8:12, reacting for 5 hours at the temperature of 40 ℃, stirring during the reaction, removing the solvent after the reaction is finished, and purifying and refining to obtain trimethylsilyl propylene epoxide;
(b) mixing water, concentrated sulfuric acid and trimethylsilyl propylene epoxide, heating to 85 ℃ in water bath under stirring, preserving heat for reaction for 10min, cooling to room temperature after the reaction is finished, and obtaining the dihydric alcohol with the trimethylsilyl lateral group shown in the formula (I) through neutralization, distillation, separation and purification, wherein R in the formula (I) is-C ((CH)3)2) The concentrated sulfuric acid is 70% sulfuric acid, the molar ratio of trimethylsilyl propylene epoxide to water is 1:25 at the beginning of the reaction, and the mass of the concentrated sulfuric acid is the mass of the mixture0.12% of sum;
(1.3) esterification reaction;
preparing terephthalic acid, ethylene glycol, diol with trimethylsilyl groups and 2, 5-di-tert-butyl-1, 6-hexanedicarboxylic acid into slurry, adding antimony trioxide, titanium dioxide and triphenyl phosphate, uniformly mixing, pressurizing in a nitrogen atmosphere to perform esterification reaction, wherein the pressurizing pressure is normal pressure, the esterification reaction temperature is 260 ℃, the esterification reaction endpoint is determined when the distilled water amount in the esterification reaction reaches 95% of a theoretical value, the molar ratio of the terephthalic acid to the ethylene glycol is 1:2.0, the sum of the addition amounts of the diol with trimethylsilyl groups and the 2, 5-di-tert-butyl-1, 6-hexanedicarboxylic acid is 5mol% of the addition amount of the terephthalic acid, the molar ratio of the diol with trimethylsilyl groups and the 2, 5-di-tert-butyl-1, 6-hexanedicarboxylic acid is 2:3, antimony trioxide, and 2, 5-di-tert-butyl-1, 6-hexanedicarboxylic acid are added, and, The addition amounts of titanium dioxide and triphenyl phosphate are 0.05wt%, 0.25wt% and 0.05wt%, respectively, of the addition amount of terephthalic acid;
(1.4) a polycondensation reaction;
after the esterification reaction is finished, starting the polycondensation reaction in a low vacuum stage under the condition of negative pressure, stably pumping the pressure in the stage from normal pressure to absolute pressure of 490Pa within 30min, controlling the reaction temperature to be 270 ℃ and the reaction time to be 90min, then continuing to pump vacuum, and carrying out the polycondensation reaction in a high vacuum stage to further reduce the reaction pressure to absolute pressure of 90Pa, control the reaction temperature to be 270 ℃ and control the reaction time to be 55min, wherein the number average molecular weight of the prepared modified polyester is 27000 and the molecular weight distribution index is 1.9;
(2) preparing low-shrinkage polyester drawn yarns;
processing the modified polyester according to an FDY process to obtain the low-shrinkage polyester drawn yarn, wherein the FDY process comprises the following steps: metering, spinneret plate extruding, cooling, oiling, stretching, heat setting, relaxation heat treatment and winding, wherein the relaxation heat treatment refers to that polyester filament bundles with 3.0% of winding overfeed rate pass through a space between a pair of hot plates which are arranged in parallel and are not coplanar and have 235 ℃ of temperature, the hot plates are positioned between the last group of heat setting rollers and the winding rollers in the FDY equipment, the length of the two hot plates is 3.8m along the running direction of the polyester filament bundles, the two ends of the two hot plates are flush, when the polyester filament bundles pass through the middle of the two hot plates, the distance between the polyester filament bundles and the two hot plates is 9mm, the distance between the last group of heat setting rollers and the winding rollers is 384mm, and the distance between the two hot plates and the last group of heat setting rollers is 280 mm;
the parameters of the FDY process are as follows: the spinning temperature is 300 ℃, the cooling temperature is 25 ℃, the network pressure is 0.30MPa, the one-roller speed is 2750m/min, the one-roller temperature is 83 ℃, the two-roller speed is 4200m/min, the two-roller temperature is 145 ℃, and the winding speed is 4420 m/min.
The finally prepared low-shrinkage polyester drawn yarn is modified polyester FDY yarn, the filament number of the low-shrinkage polyester drawn yarn is 1.3dtex, the breaking strength is 4.5cN/dtex, the elongation at break is 16.0 percent, the network degree is 13/m, the linear density deviation rate is 1.0 percent, the CV value of the breaking strength is 7.5 percent, the CV value of the elongation at break is 7.8 percent, and the shrinkage in boiling water is 2.5 percent;
the dye uptake of the low-shrinkage polyester drawn yarn at the temperature of 125 ℃ is 89.8 percent, the K/S value is 22.99, the soaping-resistant color fastness reaches 5 grade, the dry rubbing fastness reaches 5 grade, and the wet rubbing fastness reaches 6 grade.
Example 7
The preparation method of the low-shrinkage polyester drawn yarn comprises the following steps:
(1) preparing modified polyester;
(1.1) preparation of 2, 5-di-tert-butyl-1, 6-hexanedicarboxylic acid: firstly, mixing tungstic acid and hydrogen peroxide, stirring for 11min at room temperature, then adding 2, 4-di-tert-butylcyclohexanol, reacting for 1h at the temperature of 80 ℃, then heating to 95 ℃ and reacting for 2.2h, wherein reactants are always in a reflux state in the reaction process, and finally cooling, crystallizing, washing and refining, wherein the molar ratio of the tungstic acid to the 2, 4-di-tert-butylcyclohexanol to the hydrogen peroxide is 1:35:150 at the beginning of the reaction;
(1.2) preparing dihydric alcohol with trimethylsilyl lateral groups;
(a) mixing 3-trimethylsilyl-3, 3-dimethylpropene, peracetic acid and dichloromethane according to the molar ratio of 1:10:10, reacting for 6 hours at the temperature of 35 ℃, stirring during the reaction, removing the solvent after the reaction is finished, and purifying and refining to obtain trimethylsilyl propylene epoxide;
(b) mixing water, concentrated sulfuric acid and trimethylMixing silicon-based propylene epoxide, heating to 80 ℃ in water bath under the condition of stirring, preserving heat for reaction for 15min, cooling to room temperature after the reaction is finished, and obtaining the dihydric alcohol with the trimethylsilyl lateral group shown in the formula (I) through neutralization, distillation, separation and purification, wherein R in the formula (I) is-C ((CH)3)2) The concentrated sulfuric acid is sulfuric acid with the mass concentration of 70%, the molar ratio of the trimethylsilyl propylene epoxide to water is 1:35 when the reaction starts, and the mass of the concentrated sulfuric acid accounts for 0.14% of the mass sum of the mixture;
(1.3) esterification reaction;
preparing terephthalic acid, ethylene glycol, diol with trimethylsilyl groups and 2, 5-di-tert-butyl-1, 6-hexanedicarboxylic acid into slurry, adding ethylene glycol antimony, titanium dioxide and trimethyl phosphite, uniformly mixing, pressurizing in a nitrogen atmosphere to perform esterification reaction, wherein the pressurizing pressure is 0.2MPa, the esterification reaction temperature is 250 ℃, and the esterification reaction end point is reached when the water distillation amount in the esterification reaction reaches 92% of a theoretical value, wherein the molar ratio of the terephthalic acid to the ethylene glycol is 1:1.9, the sum of the addition amounts of the diol with trimethylsilyl groups and the 2, 5-di-tert-butyl-1, 6-hexanedicarboxylic acid is 4 mol% of the addition amount of the terephthalic acid, the molar ratio of the diol with trimethylsilyl groups and the 2, 5-di-tert-butyl-1, 6-hexanedicarboxylic acid is 1:2.6, and the ethylene glycol antimony, 5-di-tert-butyl-1, 6-hexanedicarboxylic acid, The addition amounts of titanium dioxide and trimethyl phosphite are 0.04 wt%, 0.22 wt% and 0.01 wt% of the addition amount of terephthalic acid, respectively;
(1.4) a polycondensation reaction;
after the esterification reaction is finished, starting the polycondensation reaction in a low vacuum stage under the condition of negative pressure, stably pumping the pressure in the stage from normal pressure to absolute pressure of 440Pa within 40min, controlling the reaction temperature to be 280 ℃ and the reaction time to be 60min, then continuing to pump vacuum, and carrying out the polycondensation reaction in a high vacuum stage to further reduce the reaction pressure to absolute pressure of 95Pa, control the reaction temperature to be 274 ℃ and control the reaction time to be 50min, wherein the number average molecular weight of the prepared modified polyester is 30000 and the molecular weight distribution index is 2.0;
(2) preparing low-shrinkage polyester drawn yarns;
processing the modified polyester according to an FDY process to obtain the low-shrinkage polyester drawn yarn, wherein the FDY process comprises the following steps: metering, spinneret plate extruding, cooling, oiling, stretching, heat setting, relaxation heat treatment and winding, wherein the relaxation heat treatment refers to that polyester filament bundles with 5.0% of winding overfeed rate pass through a space between a pair of hot plates which are arranged in parallel and are not coplanar and have the temperature of 240 ℃, the hot plates are positioned between the last group of heat setting rollers and the winding rollers in the FDY equipment, the length of the two hot plates is 4.0m along the running direction of the polyester filament bundles, the two ends of the two hot plates are flush, the distance between the polyester filament bundles and the two hot plates is 10mm when the polyester filament bundles pass through the middle of the two hot plates, the distance between the last group of heat setting rollers and the winding rollers is 400mm, and the distance between the two hot plates and the last group of heat setting rollers is 300 mm;
the parameters of the FDY process are as follows: the spinning temperature is 295 ℃, the cooling temperature is 20 ℃, the network pressure is 0.25MPa, the speed of one roller is 2800m/min, the temperature of one roller is 92 ℃, the speed of two rollers is 4500m/min, the temperature of two rollers is 125 ℃, and the winding speed is 4390 m/min.
The finally prepared low-shrinkage polyester drawn yarn is modified polyester FDY yarn, the filament number of the low-shrinkage polyester drawn yarn is 2dtex, the breaking strength is 4.65cN/dtex, the elongation at break is 19.0 percent, the network degree is 8/m, the linear density deviation rate is 1.0 percent, the CV value of the breaking strength is 7.92 percent, the CV value of the elongation at break is 7.88 percent, and the shrinkage in boiling water is 2.5 percent;
the dye uptake of the low-shrinkage polyester drawn yarn at the temperature of 125 ℃ is 89.8 percent, the K/S value is 24.34, the soaping-resistant color fastness reaches 5 grade, the dry rubbing fastness reaches 5 grade, and the wet rubbing fastness reaches 6 grade.

Claims (10)

1. The preparation method of the low-shrinkage polyester drawn yarn is characterized by comprising the following steps of: processing the modified polyester according to an FDY process, and adding a relaxation heat treatment process between a tension heat setting process and a winding process to obtain the low-shrinkage polyester drawn yarn;
the preparation method of the modified polyester comprises the following steps: uniformly mixing terephthalic acid, ethylene glycol, dihydric alcohol with trimethylsilyl lateral group and dibasic acid with tert-butyl lateral group, and then carrying out esterification reaction and polycondensation reaction in sequence;
the structural formula of the dihydric alcohol with the trimethylsilyl lateral group is as follows:
Figure DEST_PATH_IMAGE001
；
in the formula, R is-CH2-、-CH(CH3) -or-C ((CH)3)2)-；
The dibasic acid with tertiary butyl side group is 5-tertiary butyl-1, 3-phthalic acid, 2-tertiary butyl-1, 6-hexanedicarboxylic acid, 3-tertiary butyl-1, 6-hexanedicarboxylic acid or 2, 4-di-tertiary butyl-1, 6-hexanedicarboxylic acid;
the relaxation heat treatment refers to that the modified polyester tows pass through a space with a certain temperature in a proper relaxation state;
the proper relaxation state means that the overfeed rate of winding is 3.0-5.0%;
the certain temperature is 180-200 ℃;
the space with a certain temperature is a space between a pair of hot plates which are arranged in parallel and are not coplanar, and the hot plates are positioned between the last group of heat setting rollers and the winding rollers in the FDY equipment; the length of the two hot plates is 3.0-4.0 m along the running direction of the modified polyester tows, and the two ends of the two hot plates are flush; when the modified polyester filament bundle passes through the middle of the two hot plates, the distance between the modified polyester filament bundle and the two hot plates is 5-10 mm.
2. The method for preparing the low-shrinkage polyester drawn yarn as claimed in claim 1, wherein a distance between the last group of the heat setting rollers and the winding roller is 300-400 mm; the distance between the two hot plates and the last group of heat setting rollers is 200-300 mm.
3. The method for preparing the low-shrinkage polyester drawn yarn as claimed in claim 1, wherein the synthesis of the diol with trimethylsilyl group side group comprises the following steps:
(1) mixing trimethylsilyl propylene, peracetic acid and dichloromethane according to a molar ratio of 1: 5-10: 10-15, reacting for 5-8 hours at the temperature of 35-40 ℃, stirring during the reaction, removing a solvent after the reaction is finished, and purifying and refining to obtain trimethylsilyl propylene epoxide;
(2) mixing water, concentrated sulfuric acid and trimethylsilyl propylene epoxide, heating the mixture to 80-85 ℃ in a water bath under the stirring condition, carrying out heat preservation reaction for l 0-15 min, cooling the mixture to room temperature after the reaction is finished, and carrying out neutralization, distillation, separation and purification to obtain dihydric alcohol with a trimethylsilyl lateral group, wherein the concentrated sulfuric acid is sulfuric acid with the mass concentration of 70%, the molar ratio of the trimethylsilyl propylene epoxide to the water is 1: 20-40 at the beginning of the reaction, and the mass of the concentrated sulfuric acid accounts for 0.1-0.15% of the total mass of the mixture;
the structural formula of the dihydric alcohol with the trimethylsilyl lateral group is shown in the specification, wherein R is-CH (CH)3) -and-C (CH)3)2-when said trimethylsilyl propene corresponds to 3-trimethylsilyl-3-methylpropene and 3-trimethylsilyl-3, 3-dimethylpropene;
the synthesis method of the 2-tert-butyl-1, 6-hexanedicarboxylic acid, the 3-tert-butyl-1, 6-hexanedicarboxylic acid and the 2, 4-di-tert-butyl-1, 6-hexanedicarboxylic acid comprises the following steps:
firstly, mixing tungstic acid and hydrogen peroxide, stirring for 10-15 min at room temperature, then adding raw material alcohol, reacting for 1-2 h at the temperature of 80-85 ℃, then heating to 90-95 ℃ and reacting for 2-3 h, wherein reactants are always in a reflux state in the reaction process, and finally cooling, crystallizing, washing and refining;
when the reaction starts, the molar ratio of the tungstic acid to the raw material alcohol to the hydrogen peroxide is 1: 30-40: 120-150;
the raw material alcohols corresponding to the 2-tert-butyl-1, 6-hexanedicarboxylic acid, the 3-tert-butyl-1, 6-hexanedicarboxylic acid and the 2, 4-di-tert-butyl-1, 6-hexanedicarboxylic acid are respectively 2-tert-butylcyclohexanol, 4-tert-butylcyclohexanol and 2, 4-di-tert-butylcyclohexanol.
4. The method for preparing the low-shrinkage polyester drawn yarn as claimed in claim 3, wherein the modified polyester is prepared by the following steps:
(1) performing esterification reaction;
preparing terephthalic acid, ethylene glycol, diol with trimethylsilyl lateral group and diacid with tert-butyl lateral group into slurry, adding a catalyst, a delustering agent and a stabilizer, uniformly mixing, pressurizing in a nitrogen atmosphere to perform esterification reaction, wherein the pressurizing pressure is normal pressure to 0.3MPa, the esterification reaction temperature is 250-260 ℃, and the esterification reaction end point is determined when the water distillation amount in the esterification reaction reaches more than 90% of the theoretical value;
(2) performing polycondensation reaction;
after the esterification reaction is finished, starting the polycondensation reaction in a low vacuum stage under the condition of negative pressure, wherein the pressure in the stage is stably pumped from normal pressure to below 500Pa in 30-50 min, the reaction temperature is 250-260 ℃, the reaction time is 30-50 min, then continuously pumping vacuum to perform the polycondensation reaction in a high vacuum stage, so that the reaction pressure is further reduced to below 100Pa, the reaction temperature is 270-282 ℃, and the reaction time is 50-90 min.
5. The method for preparing the low-shrinkage polyester drawn yarn as claimed in claim 4, wherein the molar ratio of terephthalic acid to ethylene glycol is 1: 1.2-2.0, the sum of the addition amounts of the diol with trimethylsilyl groups and the diacid with tert-butyl side groups is 3-5 mol% of the addition amount of terephthalic acid, the molar ratio of the diol with trimethylsilyl groups to the diacid with tert-butyl side groups is 1-2: 2-3, and the addition amounts of the catalyst, the delustering agent and the stabilizer are 0.03-0.05 wt%, 0.20-0.25 wt% and 0.01-0.05 wt% of the addition amount of terephthalic acid respectively.
6. The method for preparing the low shrinkage polyester drawn yarn as claimed in claim 5, wherein the catalyst is antimony trioxide, ethylene glycol antimony or antimony acetate, the delustering agent is titanium dioxide, and the stabilizer is triphenyl phosphate, trimethyl phosphate or trimethyl phosphite.
7. The method for preparing the low-shrinkage polyester drawn yarn as claimed in claim 6, wherein the modified polyester has a number average molecular weight of 25000 to 30000 and a molecular weight distribution index of 1.8 to 2.2.
8. The method for preparing the low-shrinkage polyester drawn yarn according to claim 1, wherein the FDY process comprises the following steps: metering, spinneret plate extruding, cooling, oiling, stretching, heat setting and winding;
the FDY process comprises the following parameters: the spinning temperature is 285-300 ℃, the cooling temperature is 20-25 ℃, the network pressure is 0.20-0.30 MPa, the first roller speed is 2600-2800 m/min, the first roller temperature is 83-92 ℃, the two roller speed is 4200-4500 m/min, the two roller temperature is 125-145 ℃, and the winding speed is 4130-4420 m/min.
9. The low-shrinkage polyester drawn yarn prepared by the preparation method of the low-shrinkage polyester drawn yarn according to any one of claims 1 to 8, which is characterized in that: is modified polyester FDY yarn;
the molecular chain of the modified polyester comprises a terephthalic acid chain segment, an ethylene glycol chain segment, a dihydric alcohol chain segment with a trimethylsilyl lateral group and a dibasic acid chain segment with a tert-butyl lateral group.
10. The drawn low-shrinkage polyester yarn as claimed in claim 9, wherein the drawn low-shrinkage polyester yarn has a single filament fineness of 1 to 2dtex, a breaking strength of 4.5cN/dtex or more, an elongation at break of 18.0 ± 2.0%, a network degree of 10 ± 5/m, a linear density deviation of 1.0% or less, a breaking strength CV value of 8.0% or less, an elongation at break CV value of 8.0% or less, and a boiling water shrinkage of 3.0 ± 0.5%;
the dye uptake of the low-shrinkage polyester drawn yarn at the temperature of 125 ℃ is 86.3-89.8%, the K/S value is 22.32-24.34, the soaping-resistant color fastness reaches 5 grade, the dry rubbing fastness reaches 5 grade, and the wet rubbing fastness is higher than 4 grade.
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