CN109722732B

CN109722732B - Superfine denier polyester fiber and preparation method thereof

Info

Publication number: CN109722732B
Application number: CN201811614133.2A
Authority: CN
Inventors: 张元华; 康爱旗; 汤方明
Original assignee: Jiangsu Hengli Chemical Fiber Co Ltd
Current assignee: Jiangsu Hengli Chemical Fiber Co Ltd
Priority date: 2018-12-27
Filing date: 2018-12-27
Publication date: 2020-10-16
Anticipated expiration: 2038-12-27
Also published as: CN109722732A

Abstract

The invention relates to a superfine denier polyester fiber and a preparation method thereof, wherein the preparation method comprises the following steps: preparing modified polyester FDY yarns from the modified polyester melt according to an FDY process to obtain superfine denier polyester fibers; the prepared superfine denier polyester fiber is modified polyester FDY (fully drawn yarn), the molecular chain of the modified polyester comprises a terephthalic acid chain segment, an ethylene glycol chain segment and a main chain silicon-containing dihydric alcohol chain segment, the main chain silicon-containing dihydric alcohol is dimethyl silicon glycol, dimethyl diphenyl disiloxane glycol or tetramethyl disiloxane glycol, solid heteropoly acid powder subjected to high-temperature roasting is dispersed in the modified polyester, the high-temperature roasting temperature is 400-700 ℃, and the solid heteropoly acid is SiO₂‑TiO₂、SiO₂‑ZrO₂、B₂O₃‑Al₂O₃、TiO₂-ZnO and SiO₂-one or more of CaO. The preparation method has simple process, can effectively improve the hydrolysis rate and the dyeing property of the polyester, and the prepared product has excellent mechanical property.

Description

Superfine denier polyester fiber and preparation method thereof

Technical Field

The invention belongs to the technical field of polyester fibers, and relates to a superfine denier polyester fiber and a preparation method thereof.

Background

Polyethylene terephthalate (PET) is a polymer with excellent performance, and the PET has the advantages of high modulus, high strength, good shape retention, good barrier property and the like, so that the PET is widely applied to the fields of fibers, bottle packaging, films, sheets and the like, the yield is increased year by year, and the industrial position is remarkably improved. With the expansion of the production scale of polyester fibers, the production technology has been greatly improved, and the production of conventional products from the beginning has gradually progressed to the production direction of high-technology, functionalized and differentiated fibers, and the application field of polyester fibers has gradually progressed from the initial clothing fibers 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. There are two main ways to produce differentiated fibre products: the first method is to modify the existing fiber to obtain new performance, and the second method has the advantages of low investment, fast effect, etc. the main techniques of this method are polymer modification, superfine fiber production, profiled fiber production, composite spinning, etc.

The fine denier fiber and the superfine denier fiber are differential fibers which are developed rapidly in recent years, are high-quality and high-technology textile raw materials, and are typical representatives of new synthetic fibers which are developed from chemical fibers in the direction of high technology and high simulation. There is no well-established uniform standard for the definition of fine and ultra-fine denier fibers, and the single denier fiber is the standard by most manufacturers. I define fine denier fiber as filament number <1.2dtex and ultra fine denier fiber as filament number <0.56 dtex. When the fineness of the single filament is small to some extent, many new and different properties appear. The superfine denier fiber has small diameter and small bending resistance, and the yarn is softer; the specific surface area is large, the coverage is large, and the fabric is fluffier; the surface of the fabric has a concave-convex structure, so that the powder feeling is increased. The superfine fiber has capillary wicking property, so that the moisture permeability of the fabric is improved, the filling density is higher, and the heat retention of the fabric is better.

PET fibers have excellent physical and mechanical properties due to their regular molecular structure and high crystallinity, but this also causes difficulties in dyeing PET fibers. The molecular structure lacks active groups which can be bonded with dyes, and dyeing can be carried out only by using disperse dyes. The disperse dye belongs to nonionic dye, has larger molecular size, very low water solubility and low water absorbability of the PET fiber, and is not easy to swell in water, so that the disperse mass point of the dye is difficult to enter the fiber from the solution when the conventional method is used for dyeing. The dye uptake is low even in the boiling state. The carrier dyeing method or the high-temperature and high-pressure method is generally adopted, the carrier dyeing cost is high, and the problems are brought about in the technical aspect and the ecological aspect; the internal plasticization of the carrier facilitates the diffusion of the dye inside the fiber, but the residual carrier deteriorates the light resistance of the dye and causes contamination. The high-temperature high-pressure dyeing needs special pressure-resistant equipment, is not suitable for large-scale continuous production, and has large energy consumption and unsafe production.

In addition, with the rapid development of the PET industry, PET does not directly cause harm to the environment, but because the number of used waste products is large and resistance to air and microbial agents is strong, PET waste has become a global organic pollutant for environmental pollution. At present, common treatment methods for PET wastes include landfill, incineration and recycling, although the landfill and the incineration are the simplest methods and cause certain pollution to the environment, degradation and recycling are effective and scientific approaches for treating the PET wastes, but because the PET has a compact structure, high crystallinity and long natural degradation time, the proportion of the recycling is very small at present. Based on the requirements of enhancement of environmental consciousness, resource conservation and sustainability, natural degradation of the polyester fiber is a problem which needs to be solved urgently by science and technology workers in China.

Therefore, the research on the superfine denier polyester fiber with good dyeing property and high degradation rate has practical significance.

Disclosure of Invention

The invention aims to overcome the defects of poor dyeability and slow degradation rate of polyester fibers for clothes in the prior art, and provides the superfine polyester fibers which are modified to improve the polyester degradation rate, the polyester degradation effect and the dyeing property and the preparation method thereof.

In order to achieve the purpose, the invention adopts the following technical scheme:

a method for preparing superfine denier polyester fiber, preparing modified polyester FDY filament from modified polyester melt according to FDY process, obtaining superfine denier polyester fiber;

the preparation method of the modified polyester comprises the following steps: uniformly mixing terephthalic acid, ethylene glycol, dihydric alcohol with a silicon-containing main chain and solid heteropoly acid powder which is roasted at high temperature, and then carrying out esterification reaction and polycondensation reaction in sequence;

the dihydric alcohol with silicon-containing main chain is dimethyl silicon glycol, dimethyl diphenyl disiloxane glycol or tetramethyl disiloxane glycol; according to the invention, the diatomic alcohol with silicon-containing main chain is introduced into the polyester molecular chain, on one hand, the high molecular main chain contains-Si-O-Si-bonds, the silicon-oxygen bond gap is larger, the internal rotation activation energy is lower, the atom free rotation is facilitated, and the improvement of the mutual rotation between the high molecular chain and the chain is facilitatedForce and distance between chains, on the other hand, Si atom and-CH on the main chain of the polymer₃Is connected to-CH₃Perpendicular to the plane of the Si-O-Si atom, the-CH results from the Si-C bond being longer than the C-C bond₃Three of H are in a spread state, -CH₃Three of the supported H atoms can rotate freely to increase the distance between adjacent Si-O molecular chain segments, and moreover, inert methyl groups in the specifications of side chains prevent the approach of macromolecules, so that the macromolecular material is very flexible, and the free volume of a cavity is obviously increased compared with that of the macromolecular material without introducing dihydric alcohol containing silicon in the main chain. Disperse dyes are a class of dyes that are relatively small in molecule and structurally free of water-soluble groups, mostly in the form of particles, with a particle size of between a few hundred nanometers and a micron. When the modified polyester begins to be dyed, along with the continuous improvement of temperature, because the polyester macromolecular chain contains-Si-O-Si-bonds, the silicon-oxygen bonds are longer than the carbon-oxygen bonds, the internal rotation activation energy is lower, the molecular chain containing the carbon-oxygen bonds starts to move firstly, when the dyeing bath temperature needs to be improved to 120-130 ℃, the intensity of the movement of the macromolecular chains containing the silicon-oxygen bonds is larger than that of the molecular chains containing only the carbon-oxygen bonds, and simultaneously, because the free volume of cavities is larger, the diffusion rate of the granular dye to the interior of the fiber is obviously improved, the free volume of the cavities formed by the macromolecular chains containing the silicon-oxygen bonds is higher than that of the molecular chains containing only the carbon-oxygen bonds, so that water or other molecules such as dye and the like are easier to permeate into the modified polyester macromolecules, the dyeing and the like of the modified polyester can be positively influenced, the dyeing temperature, reduces energy consumption and improves the dye uptake of the fiber.

The high-temperature roasting temperature of the solid heteropoly acid is 400-700 ℃, the high-temperature roasting aims at removing impurities in polyester, and decomposing and activating a catalyst intermediate (the precursor of the catalyst is subjected to oxidation, reduction and other reactions in the process of going to the catalyst, the catalyst intermediate refers to a substance in the process, the components are uncertain and are generally referred to) under a certain atmosphere and temperature, the temperature is set to mainly meet the decomposition and activation conditions of the catalyst intermediate, the high-temperature roasting temperature can be adjusted within a proper range, but the adjustment range is not too large, and the high-temperature roasting temperature is highOver-temperature part of SiO in warm roasting₂The gasification can affect the set proportion, and the temperature is too low to meet the requirements of the decomposition and activation of the catalyst intermediate;

the solid heteropoly acid is SiO₂-TiO₂、SiO₂-ZrO₂、B₂O₃-Al₂O₃、TiO₂-ZnO and SiO₂-one or more of CaO.

Because the terminal carboxyl group in the polyester system is the position where polyester hydrolysis occurs first, unshared electron pairs on hydroxyl oxygen atoms in the carboxyl group are conjugated with pi electrons of carbonyl groups to generate delocalization of electrons, the delocalization results in that the action force of hydroxyl bonds is weakened, so that the carboxylic acid is dissociated into negative ions and protons, and the negative charges of the carboxyl group are evenly distributed on two oxygen atoms due to the delocalization of the electrons, so that the stability of the carboxyl negative ions is improved, and the carboxylic acid is favorably dissociated into the ions. The invention introduces solid heteropoly acid in the preparation process of polyester, and the solid heteropoly acid can be dissociated to generate H⁺Ion, H⁺The ions can attack carboxyl anions to form a tetrahedral intermediate with positive ions, so that the oxygen of the carbonyl group is protonated and the oxygen is positively charged, thereby attracting electrons on the carbonyl carbon and enabling the carbonyl carbon to have electropositivity, so that the carbonyl carbon can be more easily subjected to a nucleophilic reagent (such as H) with weaker alkalinity₂O), after the nucleophilic reagent attacks, the acyloxy of the tetrahedral intermediate is broken and decomposed into acid and alcohol, and the carbonyl is continuously destroyed, the macromolecular chain is continuously broken, the content of the terminal carboxyl is continuously increased, the hydrolysis of the polyester is further promoted, and the hydrolysis rate is improved.

Solid heteropoly acid SiO₂-TiO₂The preparation process comprises the following steps:

according to parts by weight, firstly, 1 part of silicon dioxide powder and 50-60 parts of water are stirred and dispersed, 2-3 parts of titanyl sulfate solution with the concentration of 4-5 wt% are dropwise added, then, sodium hydroxide solution with the concentration of 0.5-1.0mol/L is used for adjusting the pH value to be neutral, then, sulfuric acid with the concentration of 8-10 wt% is used for adjusting the pH value to be 8, and after aging is carried out for 1-2h, deionized water is washed until no SO exists₄ ^2-Then the mixture is filtered, the filter cake is washed by absolute ethyl alcohol for a plurality of times,then placing the mixture in a drying oven to be dried at the temperature of 100 ℃, and finally calcining the sample at the temperature of 400-700 ℃ for 2-4h respectively to obtain solid heteropoly acid SiO₂-TiO₂。

Solid heteropoly acid SiO₂-ZrO₂The preparation process comprises the following steps:

according to parts by weight, firstly, 1 part of silicon dioxide powder and 50-60 parts of water are stirred and dispersed, 2-3 parts of zirconium sulfate solution with the concentration of 4-5 wt% are dropwise added, then, sodium hydroxide solution with the concentration of 0.5-1.0mol/L is used for adjusting the pH value to be neutral, then, sulfuric acid with the concentration of 8-10 wt% is used for adjusting the pH value to be 8, and after aging is carried out for 1-2h, deionized water is washed until no SO exists₄ ^2-Then pumping filtration is carried out, the filter cake is washed by absolute ethyl alcohol for a plurality of times, then the filter cake is placed in a drying oven to be dried under the temperature condition of 100 ℃, and finally the sample is respectively calcined for 2 to 4 hours at the temperature of 400 to 700 ℃ to obtain solid heteropoly acid SiO₂-ZrO₂。

Solid heteropoly acid B₂O₃-Al₂O₃The preparation process comprises the following steps:

according to the weight portion, firstly, 2-3 portions of 4-5 wt% aluminum sulfate solution are dropwise added into 1 portion of boric acid, then 0.5-1.0mol/L sodium hydroxide solution is used for adjusting the pH value to be neutral, then 8-10 wt% sulfuric acid is used for adjusting the pH value to be 8, after aging is carried out for 1-2h, deionized water is used for washing until no SO exists₄ ^2-Then pumping filtration is carried out, the filter cake is washed by absolute ethyl alcohol for a plurality of times, then the filter cake is placed in a drying oven to be dried under the temperature condition of 100 ℃, and finally the sample is respectively calcined for 2 to 4 hours at the temperature of 400 to 700 ℃ to obtain the solid heteropoly acid B₂O₃-Al₂O₃。

Solid heteropoly acid TiO₂The specific preparation process of ZnO is as follows:

according to the weight portion, firstly, 2-3 portions of titanyl sulfate solution with the concentration of 4-5 wt% are added into 1 portion of zinc sulfate drop by drop, then sodium hydroxide solution with the concentration of 0.5-1.0mol/L is used for adjusting the pH value to be neutral, then sulfuric acid with the concentration of 8-10 wt% is used for adjusting the pH value to be 8, after aging is carried out for 1-2h, deionized water is used for washing until no SO exists₄ ^2-Then suction filtering, washing the filter cake with absolute ethyl alcohol for many times, and placing the filter cake in a drying oven at the temperature of 100 DEG CDrying, and finally calcining the sample at 400-700 ℃ for 2-4h to obtain solid heteropoly acid TiO₂-ZnO。

Solid heteropoly acid SiO₂The specific preparation process of CaO is as follows:

according to parts by weight, firstly, 1 part of silicon dioxide powder and 50-60 parts of water are stirred and dispersed, 2-3 parts of calcium sulfate solution with the concentration of 4-5 wt% are dropwise added, then, sodium hydroxide solution with the concentration of 0.5-1.0mol/L is used for adjusting the pH value to be neutral, then, sulfuric acid with the concentration of 8-10 wt% is used for adjusting the pH value to be 8, and after aging is carried out for 1-2h, deionized water is washed until no SO exists₄ ^2-Then pumping filtration is carried out, the filter cake is washed by absolute ethyl alcohol for a plurality of times and then is placed in a drying oven to be dried under the temperature condition of 100 ℃, and finally the sample is respectively calcined for 2 to 4 hours at the temperature of 400 to 700 ℃ to obtain solid heteropoly acid SiO₂-CaO。

As a preferred technical scheme:

according to the preparation method of the superfine denier polyester fiber, the high-temperature roasting time is 2-4 hours; SiO 2₂-TiO₂、SiO₂-ZrO₂、B₂O₃-Al₂O₃、TiO₂-ZnO and SiO₂TiO in CaO₂、ZrO₂、Al₂O₃The content of ZnO and CaO is respectively 30-50 wt%, 20-40 wt% and 20-50 wt%; and (3) crushing the solid heteropoly acid after high-temperature roasting to obtain powder with the average grain diameter of less than 0.5 micron.

The preparation method of the superfine denier polyester fiber comprises the following steps:

(1) performing esterification reaction;

preparing terephthalic acid, ethylene glycol and dihydric alcohol with a silicon-containing main chain into slurry, adding solid heteropoly acid powder subjected to high-temperature roasting, a catalyst, a flatting 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 a theoretical value;

(2) performing polycondensation reaction;

and 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 low vacuum stage from normal pressure to below 500Pa in 30-50 min at the reaction temperature of 250-260 ℃ for 30-50 min, then continuously pumping the 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 270-280 ℃, and the reaction time is 50-90 min.

According to the preparation method of the superfine denier polyester fiber, the molar ratio of the terephthalic acid, the glycol and the dihydric alcohol with silicon-containing main chain is 1: 1.2-2.0: 0.03-0.05, and the addition amounts of the solid heteropoly acid powder subjected to high-temperature roasting, 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 the terephthalic acid respectively. The addition amount of the dihydric alcohol with the silicon-containing main chain and the solid heteropoly acid is not limited, and the adjustment can be carried out by a person skilled in the art under the actual condition, but the adjustment range is not too large, the excessive addition amount has too large damage to the regularity of a polyester macromolecular structure, the influence on the crystallinity and the mechanical property of the fiber is too large, the production and the application of the fiber are not facilitated, and the dyeing effect and the degradation effect are not obviously improved if the addition amount is too low;

according to the preparation method of the superfine denier polyester fiber, 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.

The preparation method of the superfine denier polyester fiber comprises the steps of preparing the modified polyester, wherein the number average molecular weight of the modified polyester is 25000-30000, and the molecular weight distribution index is 1.8-2.2.

The preparation method of the superfine denier polyester fiber 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 2200-2600 m/min, the first roller temperature is 75-90 ℃, the two roller speed is 4200-4500 m/min, the two roller temperature is 115-135 ℃, and the winding speed is 4130-4415 m/min.

The invention also provides the superfine denier polyester fiber prepared by the preparation method of the superfine denier polyester fiber, which is modified polyester FDY yarn;

the molecular chain of the modified polyester comprises a terephthalic acid chain segment, an ethylene glycol chain segment and a dihydric alcohol chain segment with a silicon-containing main chain;

the modified polyester is dispersed with the solid heteropoly acid powder which is roasted at high temperature;

the filament number of the superfine denier polyester fiber is 0.28-0.35 dtex.

As a preferred technical scheme:

the superfine denier polyester fiber has the breaking strength of more than or equal to 3.7cN/dtex, the elongation at break of 30.0 +/-4.0 percent, the network degree of 14 +/-4 pieces/m, the linear density deviation rate of less than or equal to 1.00 percent, the breaking strength CV value of less than or equal to 5.00 percent, the elongation at break CV value of less than or equal to 8.0 percent and the boiling water shrinkage of 7.0 +/-0.5 percent; according to the invention, polyester is modified by the chain silicon-containing dihydric alcohol and the solid heteropoly acid, the quality and the quality of the prepared fiber are not reduced compared with the prior art, and the modified fiber still has good mechanical properties, spinnability and the like;

the dye uptake of the superfine denier polyester fiber at the temperature of 120 ℃ is 87.3-92.2%, and the K/S value is 22.06-25.34; under the same other test conditions, the dye uptake of the comparative sample under the temperature condition of 130 ℃ is 84.8 percent, the K/S value is 21.03, and the comparative sample is only different from the superfine denier polyester fiber of the invention in that the material is common polyester and solid heteropoly acid powder which is roasted at high temperature is not added;

after the superfine denier polyester fiber is placed for 60 months at the temperature of 25 ℃ and the relative humidity of 65%, the intrinsic viscosity of the superfine denier polyester fiber is reduced by 13-18%; under the same conditions, the intrinsic viscosity of the comparative sample is reduced by 3.2%, and the comparative sample is different from the superfine denier polyester fiber of the invention only in that the material is common polyester and solid heteropoly acid powder which is roasted at high temperature is not added.

The invention mechanism is as follows:

according to the invention, polyester is modified by dihydric alcohol with a silicon-containing main chain, the cavity free volume of the modified polyester is increased, and the increase of the cavity free volume can reduce the difficulty of dye molecules penetrating into the modified polyester, so that the dyeing property of the prepared superfine denier polyester fiber is greatly improved; in addition, the modification of polyester by the solid heteropoly acid can promote the nucleophilic addition reaction in the hydrolysis process and obviously improve the degradation rate.

The specific action mechanism of the dihydric alcohol with the silicon-containing main chain for modifying the polyester to improve the dyeing property of the polyester fiber is as follows:

the dihydric alcohol with the silicon-containing main chain is dimethyl silicon glycol, dimethyl diphenyl disiloxane glycol or tetramethyl disiloxane glycol, and the structural formulas are respectively as follows:

the rigidity of the high molecular chain is determined by the size of a rotation potential barrier in the molecular chain, the main chain structures are different, wherein the bond angles and bond lengths are different or the bonding modes are different, the rigidity is also different, after the diatomic alcohol with silicon in the main chain is introduced, the high molecular main chain contains-Si-O-Si-bonds, the silicon-oxygen bond gaps are larger, the internal rotation activation energy is lower, the free rotation of atoms is facilitated, and meanwhile, the Si atoms and-CH on the high molecular main chain₃Is connected to-CH₃Perpendicular to the plane of the Si-O-Si atom, the-CH results from the Si-C bond being longer than the C-C bond₃Three of H are in a spread state, -CH₃Three propped H atoms in the polymer material can freely rotate to increase the distance between adjacent Si-O molecular chain segments, and in addition, the inert methyl of the side chain blocks the approach of the high polymer, so that the high polymer material is very flexible, and the free volume of the cavity is obviously increased compared with the high polymer material without introducing the dihydric alcohol containing silicon in the main chain; when the Si atom on the main chain of the macromolecule is connected with 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 simultaneously, the rigidity of the long branched chain substituent is small, so that the micromolecule is divided into two partsThe chain chains are easy to tangle, which is not beneficial to the increase of free volume, and the introduction of the diol with silicon-containing main chain also increases the cavity free volume 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, shorten the dyeing time, reduce the energy consumption and simultaneously improve the dye uptake of the fiber.

The specific action mechanism of the solid heteropoly acid for modifying the polyester and improving the degradation performance of the polyester fiber is as follows:

the hydrolysis reaction of polyester is the reverse reaction of esterification reaction, and the essence is the breaking process of acyl-oxygen bond in ester bond, i.e. nucleophilic addition of nucleophilic reagent on carbonyl group to form tetrahedral intermediate and eliminate negative ion to complete hydrolysis. One important reason for the slow hydrolysis rate of conventional polyesters is that the carbonyl carbon atoms in the polyesters have a low capability of being attacked by nucleophiles, because the carbonyl carbon atoms in the polyesters are surrounded by electron-donating groups and lack electron-withdrawing groups, so that the carbonyl carbon atoms in the polyesters have a low capability of being attacked by nucleophiles, and often need stronger nucleophilic groups to perform nucleophilic reactions with the carbonyl carbon atoms in the polyesters.

According to the invention, solid heteropoly acid is added into the polyester preparation raw material, so that the attack capability of carbonyl carbon atoms in the polyester for receiving nucleophilic reagents is obviously improved, and the hydrolysis rate of the polyester is further improved. The solid heteropoly acid selected by the invention is a strong acid polynuclear complex acid catalyst consisting of oxygen atoms bridging heteroatoms (central atoms) and metal atoms (coordination atoms), has strong high temperature resistance and high catalytic resistance, and the catalytic function of the catalyst is derived from an acid part with catalytic activity on the surface of the solid, and the solid heteropoly acid can be added during polyester synthesis due to high temperature resistance; because the esterification reaction of the polyester is carried out under the acidic condition, and the acid can be used as a polyester esterification catalyst, the addition of the solid heteropoly acid does not generate adverse effect on the polymerization reaction, and only contributes to the esterification reaction of terephthalic acid and ethylene glycol, thereby reducing the esterification reaction temperature and the side reaction in the esterification process.

The terminal carboxyl group in the polyester system is the position where polyester hydrolysis occurs first, unshared electron pairs on hydroxyl oxygen atoms in the carboxyl group are conjugated with pi electrons of carbonyl groups to generate delocalization of electrons, the delocalization results in that the action force of hydroxyl bonds is weakened, carboxylic acid is dissociated into negative ions and protons, and the negative charges of the carboxyl group are evenly distributed on two oxygen atoms due to the delocalization of the electrons, so that the stability of the carboxyl group negative ions is improved, and the carboxylic acid is favorably dissociated into the ions. Solid heteropolyacids capable of dissociating to give H⁺Ion, H⁺The ions can attack carboxyl anions to form a tetrahedral intermediate with positive ions, so that the oxygen of the carbonyl group is protonated and the oxygen is positively charged, thereby attracting electrons on the carbonyl carbon and enabling the carbonyl carbon to have electropositivity, so that the carbonyl carbon can be more easily subjected to a nucleophilic reagent (such as H) with weaker alkalinity₂O), after the nucleophilic reagent attacks, the acyloxy of the tetrahedral intermediate is broken and decomposed into acid and alcohol, and the carbonyl is continuously destroyed, the macromolecular chain is continuously broken, the content of the terminal carboxyl is continuously increased, the hydrolysis of the polyester is further promoted, and the hydrolysis rate is improved. The conventional polyester FDY fiber has excellent mechanical properties, but the fiber has compact structure, high crystallinity and long natural degradation time, and is difficult to recycle when being used as the main application of clothes.

Has the advantages that:

(1) according to the preparation method of the superfine denier polyester fiber, disclosed by the invention, the polyester is modified by adding the solid heteropoly acid, so that the nucleophilic addition reaction in the hydrolysis process is promoted, the degradation rate of the polyester is increased, and the problem of recycling of waste clothes can be effectively solved when the superfine denier polyester fiber is used for weaving clothes;

(2) according to the preparation method of the superfine denier polyester fiber, disclosed by the invention, polyester is modified by dihydric alcohol with a silicon-containing main chain, so that the cavity free volume of the modified polyester is increased, and the dyeing property of the fiber is improved;

(3) the preparation method of the superfine denier polyester fiber has the advantages of simple process, low cost and great 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.

Example 1

A method for preparing superfine denier polyester fiber comprises the following steps:

(1) preparation of solid heteropoly acid powder SiO₂-TiO₂；

According to parts by weight, firstly, 1 part of silicon dioxide powder and 55 parts of water are stirred and dispersed, 2 parts of titanyl sulfate solution with the concentration of 4.5 wt% are dropwise added, then sodium hydroxide solution with the concentration of 1.0mol/L is used for adjusting the pH value to be neutral, then sulfuric acid with the concentration of 10 wt% is used for adjusting the pH value to be 8, and after aging is carried out for 2 hours, deionized water is washed until no SO exists₄ ^2-Then pumping filtration is carried out, the filter cake is washed by absolute ethyl alcohol for a plurality of times, then the filter cake is placed in a drying oven to be dried under the temperature condition of 100 ℃, and finally the sample is respectively calcined for 2 hours at 500 ℃ and then is crushed to obtain solid heteropoly acid SiO with the average grain diameter of 0.4 micron₂-TiO₂Powder of SiO₂-TiO₂Medium TiO 2₂In an amount of 42 wt%;

(2) preparing modified polyester;

(1.1) esterification reaction;

preparing terephthalic acid, ethylene glycol and dimethyl silicon glycol into slurry, and adding solid heteropoly acid powder SiO₂-TiO₂Mixing antimony trioxide, titanium dioxide and triphenyl phosphate uniformly, pressurizing in nitrogen atmosphere to perform esterification reaction, wherein the pressurizing pressure is 0.3MPa, the temperature of the esterification reaction is 250 ℃, and the esterification reaction is ester when the water distillate in the esterification reaction reaches 95 of a theoretical valueThe reaction end point is that the molar ratio of the phthalic acid to the ethylene glycol is 1:1.2, the adding amount of the dimethyl silicon glycol is 3mol percent of the adding amount of the terephthalic acid, and the solid heteropoly acid powder SiO is₂-TiO₂The addition amounts of the antimony trioxide, the titanium dioxide and the triphenyl phosphate are respectively 0.03 wt%, 0.22 wt% and 0.02 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, wherein the pressure in the stage is stably pumped from normal pressure to absolute pressure of 490Pa within 30min, the reaction temperature is 252 ℃, the reaction time is 35min, 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 absolute pressure of 100Pa, the reaction temperature is 270 ℃, the reaction time is 50min, and the number average molecular weight of the prepared modified polyester is 25000 and the molecular weight distribution index is 1.8;

(3) preparing superfine denier polyester fiber;

the modified polyester melt is subjected to metering, spinneret plate extrusion, cooling, oiling, stretching, heat setting and winding to prepare modified polyester FDY yarns, and the superfine denier polyester fibers are obtained; the parameters of the FDY process are as follows: the spinning temperature is 290 ℃, the cooling temperature is 24 ℃, the network pressure is 0.25MPa, the speed of one roller is 2400m/min, the temperature of one roller is 80 ℃, the speed of two rollers is 4300m/min, the temperature of two rollers is 120 ℃, and the winding speed is 4215 m/min.

The filament number of the finally prepared superfine denier polyester fiber is 0.30dtex, the breaking strength is 4.1cN/dtex, the elongation at break is 34 percent, the network degree is 10/m, the linear density deviation rate is 0.8 percent, the CV value of the breaking strength is 4.4 percent, the CV value of the elongation at break is 7.2 percent, and the shrinkage in boiling water is 6.5 percent;

the dye uptake of the superfine denier polyester fiber at the temperature of 120 ℃ is 87.3 percent, and the K/S value is 22.06;

after the superfine denier polyester fiber is placed for 60 months under the conditions that the temperature is 25 ℃ and the relative humidity is 65 percent, the intrinsic viscosity of the superfine denier polyester fiber is reduced by 13 percent.

Comparative example 1

A process for the preparation of polyester fibers, the process essentially corresponding to example 1The difference is that dimethyl silicon glycol and solid heteropoly acid powder SiO are not added in the step (1.1)₂-TiO₂. The filament number of the finally prepared polyester fiber is 0.30dtex, the breaking strength is 4.1cN/dtex, the elongation at break is 36 percent, the network degree is 10 pieces/m, the linear density deviation rate is 1.0 percent, the CV value of the breaking strength is 4.5 percent, the CV value of the elongation at break is 7.2 percent, and the shrinkage in boiling water is 6.5 percent; under the same conditions as other test conditions of example 1, the dye uptake of the polyester fiber at a temperature of 130 ℃ was 84.8%, the K/S value was 21.03, and the intrinsic viscosity decreased by 3.2% after standing at a temperature of 25 ℃ and a relative humidity of 65% for 60 months. Comparing example 1 with comparative example 1, the invention improves the dyeing property and natural degradation property of polyester fiber greatly by modifying polyester, and the mechanical property is not affected.

Comparative example 2

Compared with the example 1, the introduction of the diol containing silicon in the main chain leads the main chain of the polymer to contain-Si-O-Si bonds, so that the silicon-oxygen bond gaps are larger, the internal rotation activation energy is lower, and the free rotation of atoms is facilitated, so that the free volume of cavities is increased, and the dyeing property of the fiber is more favorably improved compared with a long branch chain substituent.

Example 2

(1) preparation of solid heteropoly acid powder SiO₂-ZrO₂；

According to parts by weight, firstly, 1 part of silicon dioxide powder and 58 parts of water are stirred and dispersed, 2 parts of 5 wt% zirconium sulfate solution is dropwise added, then 1.0mol/L sodium hydroxide solution is used for adjusting the pH value to be neutral, then 10 wt% sulfuric acid is used for adjusting the pH value to be 8, and after aging is carried out for 1h, deionized water is washed until no SO exists₄ ^2-Then pumping filtration is carried out, the filter cake is washed by absolute ethyl alcohol for a plurality of times, then the filter cake is placed in a drying oven to be dried under the temperature condition of 100 ℃, and finally the sample is calcined for 4 hours at the temperature of 400 ℃ respectively and then is crushed to obtain solid heteropoly acid SiO with the average grain diameter of 0.45 micron₂-ZrO₂Powder of SiO₂-ZrO₂Medium ZrO of₂The content of (B) is 45 wt%;

(2) preparing modified polyester;

(2.1) esterification reaction;

preparing terephthalic acid, ethylene glycol and dimethyl diphenyl disiloxane glycol into slurry, and adding solid heteropoly acid powder SiO₂-ZrO₂After evenly mixing antimony trioxide, titanium dioxide and trimethyl phosphate, pressurizing in a nitrogen atmosphere to perform esterification reaction, wherein the pressurizing pressure is 0.2MPa, the temperature of the esterification reaction is 252 ℃, the end point of the esterification reaction is when the distilled amount of water in the esterification reaction reaches 90% of a theoretical value, the molar ratio of phthalic acid to ethylene glycol is 1:1.5, the addition amount of dimethyl diphenyl disiloxane glycol is 3.2 mol% of that of terephthalic acid, and solid heteropoly acid powder SiO is prepared by mixing solid heteropoly acid powder with ethylene glycol, and the mixture is mixed uniformly₂-ZrO₂The addition amounts of the antimony trioxide, the titanium dioxide and the trimethyl phosphate are respectively 0.032 wt%, 0.04 wt%, 0.20 wt% and 0.04 wt% of the addition amount of the terephthalic acid;

(2.2) a polycondensation reaction;

after the esterification reaction is finished, starting the polycondensation reaction in a low vacuum stage under the negative pressure condition, smoothly pumping the pressure in the stage from normal pressure to absolute pressure of 420Pa within 35min, controlling the reaction temperature to be 255 ℃ and the reaction time to be 40min, 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 271 ℃ and control the reaction time to be 55min, wherein the number average molecular weight of the prepared modified polyester is 26300 and the molecular weight distribution index is 2.2;

(3) preparing superfine denier polyester fiber;

the modified polyester melt is subjected to metering, spinneret plate extrusion, cooling, oiling, stretching, heat setting and winding to prepare modified polyester FDY yarns, and the superfine denier polyester fibers are obtained; (ii) a The parameters of the FDY process are as follows: the spinning temperature is 290 ℃, the cooling temperature is 24 ℃, the network pressure is 0.25MPa, the speed of one roller is 2400m/min, the temperature of one roller is 80 ℃, the speed of two rollers is 4300m/min, the temperature of two rollers is 120 ℃, and the winding speed is 4215 m/min.

The filament number of the finally prepared superfine denier polyester fiber is 0.28dtex, the breaking strength is 3.9cN/dtex, the elongation at break is 33 percent, the network degree is 10/m, the linear density deviation rate is 0.8 percent, the CV value of the breaking strength is 4.5 percent, the CV value of the elongation at break is 7.2 percent, and the shrinkage in boiling water is 6.6 percent;

the dye uptake of the superfine denier polyester fiber at the temperature of 120 ℃ is 87.5 percent, and the K/S value is 22.36;

Example 3

(1) preparation of solid heteropolyacid powder B₂O₃-Al₂O₃；

According to parts by weight, firstly, 2.5 parts of 4 wt% aluminum sulfate solution is dropwise added into 1 part of boric acid, then the pH value is adjusted to be neutral by 1.0mol/L sodium hydroxide solution, then the pH value is adjusted to be 8 by 9 wt% sulfuric acid, and after aging for 1.5h, deionized water is washed until no SO exists₄ ^2-Then pumping filtration is carried out, the filter cake is washed by absolute ethyl alcohol for a plurality of times, then the filter cake is placed in a drying oven to be dried under the temperature condition of 100 ℃, and finally the sample is respectively calcined for 2 hours at 700 ℃ and then is crushed to obtain solid heteropoly acid B₂O₃-Al₂O₃Powder of B₂O₃-Al₂O₃Middle Al₂O₃The contents of (A) and (B) are respectively 30 wt%;

(2) preparing modified polyester;

(2.1) esterification reaction;

mixing terephthalic acid, ethylene glycol and tetramethyl disiloxane glycol into slurry, and adding solid heteropoly acid powder B₂O₃-Al₂O₃Ethylene glycol antimony, titanium dioxide and trimethyl phosphiteAfter homogenizing, pressurizing in nitrogen atmosphere to carry out esterification reaction, wherein the pressurizing pressure is 0.1MPa, the temperature of the esterification reaction is 255 ℃, the end point of the esterification reaction is when the distilled amount of water in the esterification reaction reaches 92% of the theoretical value, the molar ratio of phthalic acid to ethylene glycol is 1:1.3, the adding amount of tetramethyl disiloxane glycol is 3.4 mol% of that of terephthalic acid, and solid heteropoly acid powder B₂O₃-Al₂O₃The addition amounts of ethylene glycol antimony, titanium dioxide and trimethyl phosphite are 0.034 wt%, 0.05 wt%, 0.24 wt% and 0.01 wt% of the addition amount of terephthalic acid, respectively;

(2.2) 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 the absolute pressure of 500Pa within 45min, controlling the reaction temperature to be 256 ℃ and the reaction time to be 30min, then continuously pumping the vacuum to perform the polycondensation reaction in a high vacuum stage, further reducing the reaction pressure to the absolute pressure of 96Pa, controlling the reaction temperature to be 273 ℃ and the reaction time to be 60min, wherein the number average molecular weight of the prepared modified polyester is 25800 and the molecular weight distribution index is 2.0;

(3) preparing superfine denier polyester fiber;

The filament number of the finally prepared superfine denier polyester fiber is 0.35dtex, the breaking strength is 4.0cN/dtex, the elongation at break is 33 percent, the network degree is 10/m, the linear density deviation rate is 0.8 percent, the CV value of the breaking strength is 4.8 percent, the CV value of the elongation at break is 7.5 percent, and the shrinkage in boiling water is 6.6 percent;

the dye uptake of the superfine denier polyester fiber at the temperature of 120 ℃ is 87.9 percent, and the K/S value is 22.9;

Example 4

(1) preparation of solid heteropoly acid powder TiO₂-ZnO；

According to parts by weight, firstly, 3 parts of titanyl sulfate solution with the concentration of 5 wt% is dropwise added into 1 part of zinc sulfate, then the pH value is adjusted to be neutral by using sodium hydroxide solution with the concentration of 1.0mol/L, then the pH value is adjusted to be 8 by using sulfuric acid with the concentration of 10 wt%, and after aging is carried out for 2 hours, deionized water is washed until no SO exists₄ ^2-Then pumping filtration is carried out, the filter cake is washed by absolute ethyl alcohol for a plurality of times and then is placed in a drying oven to be dried under the temperature condition of 100 ℃, and finally, the sample is respectively calcined for 2.5 hours at the temperature of 600 ℃ and then is crushed to obtain solid heteropoly acid TiO with the average grain diameter of 0.45 micron₂-ZnO powder, TiO₂The ZnO contents of the ZnO are 35 wt%, respectively;

(2) preparing modified polyester;

(2.1) esterification reaction;

preparing terephthalic acid, ethylene glycol and dimethyl silicon glycol into slurry, and adding solid heteropoly acid powder TiO powder₂Uniformly mixing ZnO, ethylene glycol antimony, titanium dioxide and triphenyl phosphate, pressurizing in a nitrogen atmosphere to perform esterification reaction, wherein the pressurizing pressure is 0.1MPa, the temperature of the esterification reaction is 250 ℃, the end point of the esterification reaction is when the distilled amount of water in the esterification reaction reaches 95% of a theoretical value, the molar ratio of phthalic acid to ethylene glycol is 1:1.6, the addition amount of dimethyl silicon glycol is 3.6 mol% of that of terephthalic acid, and solid heteropoly acid powder TiO is solid₂-the amounts of added ZnO, ethylene glycol antimony, titanium dioxide and triphenyl phosphate are 0.036 wt%, 0.04 wt%, 0.25 wt% and 0.03 wt%, respectively, of the amount of added terephthalic acid;

(2.2) 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 260 ℃ and the reaction time to be 40min, 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 99Pa, control the reaction temperature to be 273 ℃ and control the reaction time to be 75min, wherein the number average molecular weight of the prepared modified polyester is 27000 and the molecular weight distribution index is 1.9;

(3) preparing superfine denier polyester fiber;

The filament number of the finally prepared superfine denier polyester fiber is 0.30dtex, the breaking strength is 4.0cN/dtex, the elongation at break is 33 percent, the network degree is 15/m, the linear density deviation rate is 0.8 percent, the CV value of the breaking strength is 4.6 percent, the CV value of the elongation at break is 7.5 percent, and the shrinkage in boiling water is 6.7 percent;

the dye uptake of the superfine denier polyester fiber at the temperature of 120 ℃ is 88.3 percent, and the K/S value is 23.06;

after the superfine denier polyester fiber is placed for 60 months under the conditions that the temperature is 25 ℃ and the relative humidity is 65 percent, the intrinsic viscosity of the superfine denier polyester fiber is reduced by 14 percent.

Example 5

(1) preparation of solid heteropoly acid powder SiO₂-CaO；

According to parts by weight, firstly, 1 part of silicon dioxide powder and 50 parts of water are stirred and dispersed, 3 parts of calcium sulfate solution with the concentration of 5 wt% are dropwise added, then sodium hydroxide solution with the concentration of 1.0mol/L is used for adjusting the pH value to be neutral, then sulfuric acid with the concentration of 10 wt% is used for adjusting the pH value to be 8, and after aging is carried out for 2 hours, deionized water is used for washing until no SO exists₄ ^2-Then pumping filtration is carried out, the filter cake is washed by absolute ethyl alcohol for a plurality of times and then is placed in a drying oven to be dried at the temperature of 100 ℃, and finally, the sample is respectively calcined at the temperature of 650 ℃ for 3.5h and then is crushed to obtain solid heteropoly acid SiO with the average grain diameter of 0.45 micron₂CaO powder, SiO₂CaO in the CaO in an amount of 45% by weight;

(2) preparing modified polyester;

(2.1) esterification reaction;

preparing terephthalic acid, ethylene glycol and dimethyl diphenyl disiloxane glycol into slurry, and adding solid heteropoly acid powder SiO₂Uniformly mixing CaO, antimony acetate, titanium dioxide and trimethyl phosphate, 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 when the distilled amount of water in the esterification reaction reaches 91% of a theoretical value, the molar ratio of phthalic acid to ethylene glycol is 1:1.8, the addition amount of dimethyl diphenyl disiloxane glycol is 3.8 mol% of that of terephthalic acid, and solid heteropoly acid powder SiO is₂CaO, antimony acetate, titanium dioxide and trimethyl phosphate are added in amounts of 0.038 wt%, 0.03 wt%, 0.25 wt% and 0.01 wt%, respectively, of the amount of terephthalic acid added;

(2.2) a polycondensation reaction;

after the esterification reaction is finished, starting the polycondensation reaction in a low vacuum stage under the negative pressure condition, stably pumping the pressure in the stage from normal pressure to absolute pressure of 490Pa within 50min, at the reaction temperature of 258 ℃ for 35min, 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 absolute pressure of 100Pa, the reaction temperature is 274 ℃, the reaction time is 80min, and the number average molecular weight of the prepared modified polyester is 28000 and the molecular weight distribution index is 2.1;

(3) preparing superfine denier polyester fiber;

The filament number of the finally prepared superfine denier polyester fiber is 0.3dtex, the breaking strength is 4.0cN/dtex, the elongation at break is 32 percent, the network degree is 15/m, the linear density deviation rate is 0.8 percent, the CV value of the breaking strength is 4.5 percent, the CV value of the elongation at break is 7.6 percent, and the shrinkage in boiling water is 6.7 percent;

the dye uptake of the superfine denier polyester fiber at the temperature of 120 ℃ is 88.8 percent, and the K/S value is 23.36;

Example 6

(1) preparing solid heteropoly acid powder;

the solid heteropoly acid powder is made of SiO with average grain diameter of 0.45 micron₂-TiO₂Powder and SiO₂-ZrO₂The powder is obtained by mixing according to the mass ratio of 1:1, wherein SiO is₂-TiO₂And SiO₂-ZrO₂Medium TiO 2₂And ZrO₂The contents of (A) are respectively 30 wt% and 50 wt%;

(2) preparing modified polyester;

(2.1) esterification reaction;

preparing terephthalic acid, ethylene glycol and tetramethyl disiloxane glycol into slurry, adding solid heteropoly acid powder, antimony acetate, titanium dioxide and trimethyl phosphite, uniformly mixing, pressurizing in a nitrogen atmosphere to perform esterification reaction, wherein the pressurizing pressure is normal pressure, the esterification reaction temperature is 254 ℃, the esterification reaction endpoint is when the water distillation amount in the esterification reaction reaches 94% of a theoretical value, the molar ratio of the phthalic acid to the ethylene glycol is 1:2.0, the adding amount of the tetramethyl disiloxane glycol is 4.0 mol% of the adding amount of the terephthalic acid, and the adding amounts of the solid heteropoly acid powder, the antimony acetate, the titanium dioxide and the trimethyl phosphite are respectively 0.04 wt%, 0.20 wt% and 0.05 wt% of the adding amount of the terephthalic acid;

(2.2) 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 450Pa within 35min, controlling the reaction temperature to be 250 ℃ and the reaction time to be 50min, 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 100Pa, control the reaction temperature to be 275 ℃ and control the reaction time to be 85min, wherein the number average molecular weight of the prepared modified polyester is 29000 and the molecular weight distribution index is 1.9;

(3) preparing superfine denier polyester fiber;

The filament number of the finally prepared superfine denier polyester fiber is 0.3dtex, the breaking strength is 4.0cN/dtex, the elongation at break is 30 percent, the network degree is 10/m, the linear density deviation rate is 0.8 percent, the CV value of the breaking strength is 4.5 percent, the CV value of the elongation at break is 7.4 percent, and the shrinkage in boiling water is 6.8 percent;

the dye uptake of the superfine denier polyester fiber at the temperature of 120 ℃ is 89.3 percent, and the K/S value is 23.34;

Example 7

(1) preparing solid heteropoly acid powder;

the solid heteropoly acid powder is made of SiO with average grain diameter of 0.45 micron₂-TiO₂Powder, B₂O₃-Al₂O₃Powder and SiO₂-ZrO₂The powder is obtained by mixing according to the mass ratio of 1:1:1, wherein SiO is₂-TiO₂、B₂O₃-Al₂O₃And SiO₂-ZrO₂Medium TiO 2₂、Al₂O₃And ZrO₂The contents of (A) are 50 wt%, 20 wt% and 20 wt%, respectively;

(2) preparing modified polyester;

(2.1) esterification reaction;

preparing terephthalic acid, ethylene glycol and tetramethyldisiloxane glycol into slurry, adding solid heteropolyacid powder, antimony trioxide, 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 260 ℃, the esterification reaction endpoint is determined when the distilled amount of water in the esterification reaction reaches 99% of a theoretical value, the molar ratio of the phthalic acid to the ethylene glycol is 1:1.3, the adding amount of the tetramethyldisiloxane glycol is 4.2 mol% of the adding amount of the terephthalic acid, and the adding amounts of the solid heteropolyacid powder, the antimony trioxide, the titanium dioxide and the trimethyl phosphate are respectively 0.042 wt%, 0.04 wt%, 0.21 wt% and 0.01 wt% of the adding amount of the terephthalic acid;

(2.2) 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 the absolute pressure of 500Pa within 45min, controlling the reaction temperature to be 250 ℃ and the reaction time to be 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 90Pa, the reaction temperature is 280 ℃ and the reaction time is 90min, wherein the number average molecular weight of the prepared modified polyester is 30000 and the molecular weight distribution index is 1.8;

(3) preparing superfine denier polyester fiber;

the modified polyester melt is subjected to metering, spinneret plate extrusion, cooling, oiling, stretching, heat setting and winding to prepare modified polyester FDY yarns, and the superfine denier polyester fibers are obtained; 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 one-roller speed is 2200m/min, the one-roller temperature is 75 ℃, the two-roller speed is 4200m/min, the two-roller temperature is 115 ℃, and the winding speed is 4130 m/min.

The filament number of the finally prepared superfine denier polyester fiber is 0.3dtex, the breaking strength is 4.1cN/dtex, the elongation at break is 30 percent, the network degree is 10/m, the linear density deviation rate is 0.8 percent, the CV value of the breaking strength is 4.5 percent, the CV value of the elongation at break is 7.5 percent, and the shrinkage in boiling water is 6.9 percent;

the dye uptake of the superfine denier polyester fiber at the temperature of 120 ℃ is 89.6 percent, and the K/S value is 23.71;

Example 8

(1) preparing modified polyester;

(1.1) esterification reaction;

preparing terephthalic acid, ethylene glycol and dimethyl silicon glycol into slurry, and adding solid heteropoly acid powder B₂O₃-Al₂O₃After uniformly mixing antimony trioxide, titanium dioxide and triphenyl phosphate, pressurizing in a nitrogen atmosphere to perform esterification reaction, wherein the pressurizing pressure is 0.3MPa, the temperature of the esterification reaction is 250 ℃, the end point of the esterification reaction is when the distilled amount of water in the esterification reaction reaches 95 of a theoretical value, the molar ratio of phthalic acid to ethylene glycol is 1:1.2, the addition amount of dimethyl silicon glycol is 4.3 mol% of that of terephthalic acid, and solid heteropoly acid powder B₂O₃-Al₂O₃The addition amounts of the antimony trioxide, the titanium dioxide and the triphenyl phosphate are respectively 0.043 wt%, 0.03 wt%, 0.22 wt% and 0.02 wt% of the addition amount of the terephthalic acid, and the solid heteropoly acid powder B₂O₃-Al₂O₃Has an average particle diameter of 0.4 μm, B₂O₃-Al₂O₃Middle Al₂O₃The contents of (A) and (B) are respectively 40 wt%; (ii) a

(1.2) polycondensation reaction;

(2) preparing superfine denier polyester fiber;

The filament number of the finally prepared superfine denier polyester fiber is 0.3dtex, the breaking strength is 4.0cN/dtex, the elongation at break is 30 percent, the network degree is 15/m, the linear density deviation rate is 0.8 percent, the CV value of the breaking strength is 4.6 percent, the CV value of the elongation at break is 7.6 percent, and the shrinkage in boiling water is 6.9 percent;

the dye uptake of the superfine denier polyester fiber at the temperature of 120 ℃ is 89.9 percent, and the K/S value is 24.24;

Example 9

(1) preparing modified polyester;

(1.1) esterification reaction;

preparing terephthalic acid, ethylene glycol and dimethyl diphenyl disiloxane glycol into slurry, and adding solid heteropoly acid powder TiO₂Uniformly mixing ZnO, antimony trioxide, titanium dioxide and trimethyl phosphate, pressurizing in a nitrogen atmosphere to perform esterification reaction, wherein the pressurizing pressure is 0.2MPa, the esterification reaction temperature is 252 ℃, the esterification reaction endpoint is when the water distillate in the esterification reaction reaches 90% of a theoretical value, the molar ratio of phthalic acid to ethylene glycol is 1:1.5, the addition amount of dimethyl diphenyl disiloxane glycol is 4.4 mol% of that of terephthalic acid, and solid heteropoly acid powder TiO powder is obtained₂The amounts of ZnO, antimony trioxide, titanium dioxide and trimethyl phosphate added are terephthalic acid respectively0.045 wt%, 0.04 wt%, 0.20 wt% and 0.04 wt% of the addition amount, solid heteropoly acid powder TiO₂-ZnO average particle size 0.4 micron, TiO₂-the content of ZnO in ZnO is 20 wt%;

(1.2) polycondensation reaction;

(2) preparing superfine denier polyester fiber;

the modified polyester melt is subjected to metering, spinneret plate extrusion, cooling, oiling, stretching, heat setting and winding to prepare modified polyester FDY yarns, and the superfine denier polyester fibers are obtained; 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 speed of one roller is 2600m/min, the temperature of one roller is 90 ℃, the speed of two rollers is 4500m/min, the temperature of two rollers is 135 ℃, and the winding speed is 4415 m/min.

The filament number of the finally prepared superfine denier polyester fiber is 0.32dtex, the breaking strength is 3.9cN/dtex, the elongation at break is 28 percent, the network degree is 10/m, the linear density deviation rate is 0.7 percent, the CV value of the breaking strength is 4.7 percent, the CV value of the elongation at break is 7.5 percent, and the shrinkage in boiling water is 7.0 percent;

the dye uptake of the superfine denier polyester fiber at the temperature of 120 ℃ is 90.2 percent, and the K/S value is 23.84;

after the superfine denier polyester fiber is placed for 60 months under the conditions that the temperature is 25 ℃ and the relative humidity is 65 percent, the intrinsic viscosity of the superfine denier polyester fiber is reduced by 15 percent.

Example 10

(1) preparing modified polyester;

(1.1) esterification reaction;

will be benzene to benzenePreparing slurry from dicarboxylic acid, ethylene glycol and tetramethyl disiloxane glycol, and adding solid heteropoly acid powder TiO₂Uniformly mixing ZnO, ethylene glycol antimony, titanium dioxide and trimethyl phosphite, pressurizing in a nitrogen atmosphere to perform esterification reaction, wherein the pressurizing pressure is 0.1MPa, the esterification reaction temperature is 255 ℃, the esterification reaction endpoint is when the distilled amount of water in the esterification reaction reaches 92% of a theoretical value, the molar ratio of phthalic acid to ethylene glycol is 1:1.3, the addition amount of tetramethyl disiloxane glycol is 4.5 mol% of that of terephthalic acid, and solid heteropoly acid powder TiO powder is₂The addition amounts of ZnO, ethylene glycol antimony, titanium dioxide and trimethyl phosphite were 0.045 wt%, 0.05 wt%, 0.24 wt% and 0.01 wt%, respectively, of the addition amount of terephthalic acid, and solid heteropoly acid powder TiO₂-ZnO average particle size 0.4 micron, TiO₂-the content of ZnO in ZnO is 40 wt%;

(1.2) polycondensation reaction;

(2) preparing superfine denier polyester fiber;

The filament number of the finally prepared superfine denier polyester fiber is 0.3dtex, the breaking strength is 4.0cN/dtex, the elongation at break is 28 percent, the network degree is 15/m, the linear density deviation rate is 0.8 percent, the CV value of the breaking strength is 4.5 percent, the CV value of the elongation at break is 7.6 percent, and the shrinkage in boiling water is 7.2 percent;

the dye uptake of the superfine denier polyester fiber at the temperature of 120 ℃ is 91.2 percent, and the K/S value is 24.88;

after the superfine denier polyester fiber is placed for 60 months under the conditions that the temperature is 25 ℃ and the relative humidity is 65 percent, the intrinsic viscosity of the superfine denier polyester fiber is reduced by 16 percent.

Example 11

(1) preparing modified polyester;

(1.1) esterification reaction;

preparing terephthalic acid, ethylene glycol and dimethyl silicon glycol into slurry, and adding solid heteropoly acid powder SiO₂Uniformly mixing CaO, ethylene glycol antimony, titanium dioxide and triphenyl phosphate, 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 when the distilled amount of water in the esterification reaction reaches 95% of a theoretical value, the molar ratio of phthalic acid to ethylene glycol is 1:1.6, the addition amount of dimethyl silicon glycol is 4.7 mol% of that of terephthalic acid, and solid heteropoly acid powder SiO is₂The addition amounts of CaO, ethylene glycol antimony, titanium dioxide and triphenyl phosphate are 0.048 wt%, 0.04 wt%, 0.25 wt% and 0.03 wt% of the addition amount of terephthalic acid, respectively, and solid heteropoly acid powder SiO₂CaO having an average particle size of 0.4. mu.m, SiO₂The CaO content of CaO is 20% by weight;

(1.2) polycondensation reaction;

(2) preparing superfine denier polyester fiber;

The filament number of the finally prepared superfine denier polyester fiber is 0.3dtex, the breaking strength is 4.0cN/dtex, the elongation at break is 28 percent, the network degree is 10/m, the linear density deviation rate is 0.8 percent, the breaking strength CV value is 5.00 percent, the elongation at break CV value is 8.0 percent, and the boiling water shrinkage rate is 7.4 percent;

the dye uptake of the superfine denier polyester fiber at the temperature of 120 ℃ is 91.7 percent, and the K/S value is 24.99;

after the superfine denier polyester fiber is placed for 60 months under the conditions that the temperature is 25 ℃ and the relative humidity is 65 percent, the intrinsic viscosity of the superfine denier polyester fiber is reduced by 17 percent.

Example 12

(1) preparing modified polyester;

(1.1) esterification reaction;

preparing terephthalic acid, ethylene glycol and dimethyl silicon glycol into slurry, and adding solid heteropoly acid powder SiO₂Uniformly mixing CaO, ethylene glycol antimony, titanium dioxide and triphenyl phosphate, 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 when the distilled amount of water in the esterification reaction reaches 95% of a theoretical value, the molar ratio of phthalic acid to ethylene glycol is 1:1.6, the addition amount of dimethyl silicon glycol is 4.9 mol% of that of terephthalic acid, and solid heteropoly acid powder SiO is₂The addition amounts of CaO, ethylene glycol antimony, titanium dioxide and triphenyl phosphate are 0.048 wt%, 0.04 wt%, 0.25 wt% and 0.03 wt% of the addition amount of terephthalic acid, respectively, and solid heteropoly acid powder SiO₂CaO having an average particle size of 0.4. mu.m, SiO₂CaO in the CaO in an amount of 50% by weight;

(1.2) polycondensation reaction;

(2) preparing superfine denier polyester fiber;

The filament number of the finally prepared superfine denier polyester fiber is 0.3dtex, the breaking strength is 3.7cN/dtex, the elongation at break is 26 percent, the network degree is 10/m, the linear density deviation rate is 1.00 percent, the CV value of the breaking strength is 4.8 percent, the CV value of the elongation at break is 7.8 percent, and the shrinkage in boiling water is 7.5 percent;

the dye uptake of the superfine denier polyester fiber at the temperature of 120 ℃ is 92.2 percent, and the K/S value is 25.34;

after the superfine denier polyester fiber is placed for 60 months under the conditions that the temperature is 25 ℃ and the relative humidity is 65 percent, the intrinsic viscosity of the superfine denier polyester fiber is reduced by 18 percent.

Claims

1. A method for preparing superfine denier polyester fiber is characterized in that: preparing modified polyester FDY yarns from the modified polyester melt according to an FDY process to obtain superfine denier polyester fibers;

the molar ratio of the terephthalic acid to the glycol containing silicon in the main chain is 1: 1.2-2.0: 0.03-0.05;

the dihydric alcohol with silicon-containing main chain is dimethyl silicon glycol, dimethyl diphenyl disiloxane glycol or tetramethyl disiloxane glycol;

the high-temperature roasting temperature of the solid heteropoly acid is 400-700 ℃, and the solid heteropoly acid is SiO₂-TiO₂、SiO₂-ZrO₂、B₂O₃-Al₂O₃、TiO₂-ZnO and SiO₂-one or more of CaO.

2. The method for preparing the superfine denier polyester fiber according to claim 1, wherein the high temperature roasting time is 2-4 h; SiO 2₂-TiO₂、SiO₂-ZrO₂、B₂O₃-Al₂O₃、TiO₂-ZnO and SiO₂TiO in CaO₂、ZrO₂、Al₂O₃The content of ZnO and CaO is respectively 30-50 wt%, 20-40 wt% and 20-50 wt%; and (3) crushing the solid heteropoly acid after high-temperature roasting to obtain powder with the average grain diameter of less than 0.5 micron.

3. The method for preparing the superfine denier polyester fiber according to claim 2, wherein the modified polyester is prepared by the following steps:

(1) performing esterification reaction;

(2) performing polycondensation reaction;

4. The method for preparing the superfine denier polyester fiber of claim 3, wherein the solid heteropoly acid powder after high temperature roasting, the catalyst, the delustering agent and the stabilizer are added in an amount of 0.03-0.05 wt%, 0.20-0.25 wt% and 0.01-0.05 wt% of the terephthalic acid.

5. The method of claim 4, wherein the catalyst is antimony trioxide, ethylene glycol antimony or antimony acetate, the matting agent is titanium dioxide, and the stabilizer is triphenyl phosphate, trimethyl phosphate or trimethyl phosphite.

6. The method for preparing the superfine denier polyester fiber according to claim 5, 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.

7. The method for preparing the superfine denier polyester fiber according to claim 6, wherein the FDY process comprises the following steps: metering, spinneret plate extruding, cooling, oiling, stretching, heat setting and winding;

8. A super fine denier polyester fiber produced by the method of any one of claims 1 to 7, wherein: is modified polyester FDY yarn;

the filament number of the superfine denier polyester fiber is 0.28-0.35 dtex.

9. The superfine denier polyester fiber of claim 8, wherein the superfine denier polyester fiber has breaking strength of 3.7cN/dtex or more, elongation at break of 30.0 +/-4.0%, network degree of 14 +/-4/m, linear density deviation rate of 1.00% or less, breaking strength CV value of 5.00% or less, elongation at break CV value of 8.0% or less, and boiling water shrinkage of 7.0 +/-0.5%.

10. The superfine denier polyester fiber of claim 8, wherein the superfine denier polyester fiber has a dye uptake of 87.3-92.2% at a temperature of 120 ℃, and a K/S value of 22.06-25.34; after the superfine denier polyester fiber is placed for 60 months under the conditions that the temperature is 25 ℃ and the relative humidity is 65%, the intrinsic viscosity of the superfine denier polyester fiber is reduced by 13-18%.