Wool-like polyester filament and preparing method thereof

Abstract

A type of wool-like polyester filament and preparing method thereof are disclosed. The preparing method is manufacturing filament from a modified polyester through a POY process and a successive DTY processes, wherein the modified polyester is the product of the esterification and the successive polycondensation reactions of evenly mixed terephthalic acid, 1,4-butanediol, fluorinated dicarboxylic acid, tert-butyl branched hexanediol and 2,5,6,6-tetramethyl-2,5-heptanediol. The obtained fiber has a dye uptake of 90.32-93.27% and a K/S value of 22.15-23.42 when dyed at 100° C., and has an intrinsic viscosity drop of 17-20% when stored at 25° C. and R.H. 65% for 60 months. This invention features a method with ease of application and a product with good dyeing and degradation performance.

Claims

1. A preparing method for a wool-like polyester filament, characterized by manufacturing filament from a modified polyester through a partially orientated yarn (POY) process and successive drawn textured yarn (DTY) processes; wherein the modified polyester is a product of an esterification and successive polycondensation reactions of an evenly mixed mixture of terephthalic acid, 1,4-butanediol, a fluorinated dicarboxylic acid, a tert-butyl branched hexanediol and 2,5,6,6-tetramethyl-2,5-heptanediol; wherein the fluorinated dicarboxylic acid is selected from the group consisting of 2,2-difluoro-1,3-malonic acid, 2,2-difluoro-1,4-succinic acid, 2,2-difluoro-1,5-glutaric acid and 2,2,3,3-tetrafluoro-1,4-succinic acid; wherein the tert-butyl branched hexanediol has a molecular formula of ##STR00008## with R standing for —H, —CH.sub.2CH.sub.3 or —C(CH.sub.3).sub.3; wherein the 2,5,6,6-tetramethyl-2,5-heptanediol has a molecular formula of ##STR00009## wherein the DTY processes involve a first heating chamber temperature and a second heating chamber temperature, and the DTY processes involve technical parameters of 620-710 m/min for a spinning speed and 110-140° C. for the second heating chamber temperature.

2. The preparing method of claim 1, wherein the tert-butyl branched hexanediol is synthesized by means of: mixing a 300-350 g/L solution of material A and a 200-300 g/L solution of dilute sulfuric acid at a molar ratio of (1.5-2):1 of the material A to the sulfuric acid to form a mixed solution, and adding the mixed solution into an electrolytic cell, then cooling the mixed solution to 10-15° C. and carrying out an electrolytic reduction until a concentration of the material A decreases to less 10 wt %, and finally obtaining the tert-butyl branched hexanediol through a series of processes of cooling crystallization, separation and purification; wherein the material A is 2,2-methylpropionaldehyde, 2,2-dimethyl-3-pentanone or 2,2,4,4-tetramethyl-3-pentanone when R in Formula 1 stands for —H, —CH.sub.2CH.sub.3 or —C(CH.sub.3).sub.3, respectively; wherein the 2,5,6,6-tetramethyl-2,5-heptanediol is synthesized by means of: (1) mixing KOH, 3-methyl-3-hydroxybutyne, 3,3-dimethyl-2-butanone and isopropyl ether in a molar ratio of (1-1.2):1:(1.2-1.3):(2.0-3.0), then carrying out the reaction in an ice bath for 2-4 hrs, finally obtaining octyne diol through a series of processes of cooling crystallization, centrifugation, washing, refining and drying, (2) mixing the octyne diol, an alcohol and a Pd catalyst in a weight ratio of (2-3):10:(0.01-0.03), then carrying out the reaction with a continuous hydrogen input at 40-50° C. for 50-60 min, finally obtaining the 2,5,6,6-tetramethyl-2,5-heptanediol through a series of processes of separation and purification.

3. The preparing method of claim 2, wherein the modified polyester is prepared by means of: (1) Esterification concocting the terephthalic acid, the 1,4-butanediol, the fluorinated dicarboxylic acid, the tert-butyl branched hexanediol and the 2,5,6,6-tetramethyl-2,5-heptanediol into a slurry, then adding in a matting agent and a stabilizer and carrying out the esterification in a nitrogen atmosphere with a pressure 1 KPa less than an absolute pressure at 180-220° C., finally ending the esterification when a water distillation rate reaches more than 90% of a theoretical value; (2) Polycondensation adding a catalyst into products of the esterification, then smoothly reducing the pressure to less than 500 Pa within 30-50 min and carrying out the polycondensation at 250-260° C. for 30-50 min, successively, further reducing the pressure to less than 100 Pa and continuing the polycondensation at 265-270° C. for 50-70 min.

4. The preparing method of claim 3, wherein a molar ratio of the terephthalic acid and the 1,4-butanediol is 1:(1.2-2.0), and a total addition of the fluorinated dicarboxylic acid, the tert-butyl branched hexanediol and the 2,5,6,6-tetramethyl-2,5-heptanediol is 3-5 mol % of an amount of the terephthalic acid, wherein a molar ratio of the fluorinated dicarboxylic acid, the tert-butyl branched hexanediol and the 2,5,6,6-tetramethyl-2,5-heptanediol is (3-4):(1-2):(3-4), while an amount of the catalyst, the matting agent and the stabilizer is 0.03-0.05 wt %, 0.20-0.25 wt % and 0.01-0.05 wt % of the amount of the terephthalic acid, respectively.

5. The preparing method of claim 4, wherein the catalyst is tetrabutyl titanate, wherein the matting agent is titanium dioxide, and wherein the stabilizer is triphenyl phosphate, trimethyl phosphate or trimethyl phosphite.

6. The preparing method of claim 5, wherein the modified polyester has a molecular weight of 25000-30000 Da and a molecular weight distribution index of 1.9-2.4.

7. The preparing method of claim 1, wherein the POY process comprises steps of metering, spinneret extruding, cooling, oiling, stretching, heat setting and winding; wherein the POY process involves the parameters of 265-275° C. for a spinning temperature, 20-22° C. for a cooling temperature, 2800-3000 m/min for a winding speed; wherein each of the DTY processes comprises steps of filament guiding, hot stretching, false-twisting, heat setting and winding; wherein the DTY processes involve parameters of 3.5-5.5% for a setting over-feed ratio, 2.5-5.0% for a winding over-feed ratio, 200-220° C. for the first heating chamber temperature, 1.4-1.5 for a draw ratio.

8. A wool-like polyester filament prepared by the preparing method of claim 1, which is characterized by a modified polyester DTY with a monofilament fineness of 2.0-2.7 dtex; wherein the modified polyester has a molecular chain structure composed of terephthalic acid segments, 1,4-butanediol segments, fluorinated dicarboxylic acid segments, tert-butyl branched hexanediol segments and 2,5,6,6-tetramethyl-2,5-heptanediol segments; wherein the modified polyester is further dispersed with a matting agent and a doped Bi.sub.2O.sub.3 powder, and a content of the matting agent is 0.20-0.25 wt %.

9. The wool-like polyester filament of claim 8, wherein the wool-like polyester filament is characterized by mechanical performance indices of breaking strength ≥3.0 cN/dtex, breaking strength CV value ≤5.0%, elongation at break 30.0±4.0%, elongation at break CV value ≤8.0%, boiling water shrinkage rate 6.5±0.5%, oil content 2.5±0.5 wt %, interlacing degree 60±10/m, and crimp ratio 40±4.0%.

10. The wool-like polyester filament of claim 8, wherein the wool-like polyester filament is characterized by dyeing performance indices of dye uptake 90.32-93.27% (dyed at 100° C.), K/S value 22.15-23.42, color fastness to soaping level 4, color fastness to dry crocking level 4, and color fastness to wet crocking >level 4; and by an intrinsic viscosity drop of 17-20% after a storage at 25° C. and R.H. 65% for 60 months.

11. The wool-like polyester filament of claim 8, wherein the tert-butyl branched hexanediol is synthesized by means of: mixing a 300-350 g/L solution of material A and a 200-300 g/L dilute solution of sulfuric acid at a molar ratio of (1.5-2):1 of the material A to the sulfuric acid to form a mixed solution, and adding the mixed solution into an electrolytic cell, then cooling the mixed solution to 10-15° C. and carrying out an electrolytic reduction until a concentration of the material A decreases to less 10 wt %, and finally obtaining the tert-butyl branched hexanediol through a series of processes of cooling crystallization, separation and purification; wherein the material A is 2,2-methylpropionaldehyde, 2,2-dimethyl-3-pentanone or 2,2,4,4-tetramethyl-3-pentanone when R in Formula 1 stands for —H, —CH.sub.2CH.sub.3 or —C(CH.sub.3).sub.3, respectively; wherein the 2,5,6,6-tetramethyl-2,5-heptanediol is synthesized by means of: (1) mixing KOH, 3-methyl-3-hydroxybutyne, 3,3-dimethyl-2-butanone and isopropyl ether in a molar ratio of (1-1.2):1:(1.2-1.3):(2.0-3.0), then carrying out the reaction in an ice bath for 2-4 hrs, finally obtaining octyne diol through a series of processes of cooling crystallization, centrifugation, washing, refining and drying, (2) mixing the octyne diol, an alcohol and a Pd catalyst in a weight ratio of (2-3):10:(0.01-0.03), then carrying out the reaction with a continuous hydrogen input at 40-50° C. for 50-60 min, finally obtaining the 2,5,6,6-tetramethyl-2,5-heptanediol through a series of processes of separation and purification.

12. The wool-like polyester filament of claim 11, wherein the modified polyester is prepared by means of: (1) Esterification concocting the terephthalic acid, the 1,4-butanediol, the fluorinated dicarboxylic acid, the tert-butyl branched hexanediol and the 2,5,6,6-tetramethyl-2,5-heptanediol into a slurry, then adding in the matting agent and a stabilizer and carrying out the esterification in a nitrogen atmosphere with a pressure 1 KPa less than an absolute pressure at 180-220° C., finally ending the esterification when a water distillation rate reaches more than 90% of a theoretical value; (2) Polycondensation adding a catalyst into products of the esterification, then smoothly reducing the pressure to less than 500 Pa within 30-50 min and carrying out the polycondensation at 250-260° C. for 30-50 min, successively, further reducing the pressure to less than 100 Pa and continuing the polycondensation at 265-270° C. for 50-70 min.

13. The wool-like polyester filament of claim 12, wherein a molar ratio of the terephthalic acid and the 1,4-butanediol is 1:(1.2-2.0), and a total addition of the fluorinated dicarboxylic acid, the tert-butyl branched hexanediol and the 2,5,6,6-tetramethyl-2,5-heptanediol is 3-5 mol % of an amount of the terephthalic acid, wherein a molar ratio of the fluorinated dicarboxylic acid, the tert-butyl branched hexanediol and the 2,5,6,6-tetramethyl-2,5-heptanediol is (3-4):(1-2):(3-4), while an amount of the catalyst, the matting agent and the stabilizer is 0.03-0.05 wt %, 0.20-0.25 wt % and 0.01-0.05 wt % of the amount of the terephthalic acid, respectively.

14. The wool-like polyester filament of claim 13, wherein the catalyst is tetrabutyl titanate, wherein the matting agent is titanium dioxide, and wherein the stabilizer is triphenyl phosphate, trimethyl phosphate or trimethyl phosphite.

15. The wool-like polyester filament of claim 8, wherein the modified polyester has a molecular weight of 25000-30000 Da and a molecular weight distribution index of 1.9-2.4.

16. The wool-like polyester filament of claim 8, wherein the POY process comprises steps of metering, spinneret extruding, cooling, oiling, stretching, heat setting and winding; wherein the POY process involves the parameters of 265-275° C. for a spinning temperature, 20-22° C. for a cooling temperature, 2800-3000 m/min for a winding speed; wherein each of the DTY processes comprises steps of filament guiding, hot stretching, false-twisting, heat setting and winding; wherein the DTY processes involve parameters of 3.5-5.5% for a setting over-feed ratio, 2.5-5.0% for a winding over-feed ratio, 200-220° C. for the first heating chamber temperature, 1.4-1.5 for a draw ratio.

Description

BRIEF DESCRIPTION OF THE DRAWING

(1) FIGURE is the diagram of equipment for synthesizing the tert-butyl branched hexanediol.

DETAILED DESCRIPTION OF THE EMBODIMENTS

(2) Based on above mentioned method, the following embodiments are carried out for further demonstration in the present invention. It is to be understood that these embodiments are only intended to illustrate the invention and are not intended to limit the scope of the invention. In addition, it should be understood that after reading the contents described in the present invention, those technical personnel in this field can make various changes or modifications to the invention, and these equivalent forms also fall within the scope of the claims attached to the application.

Example 1

(3) A method for preparing the wool-like polyester filament, comprising the steps:

(4) (1) Preparation of modified polyester

(5) (1.1) Synthesizing 2,2,5,5-tetramethyl-3,4-hexanediol

(6) (a) mixing 320 g/L of 2,2-methylpropionaldehyde solution and 200 g/L of dilute sulfuric acid solution in the mole ratio 1.5:1 of 2,2-methylpropionaldehyde to sulfuric acid at first, and adding the mixture into a electrolytic cell, then cooling the mixed solution to 12° C. and carrying out the electrolytic reduction until the concentration of 2,2-methylpropionaldehyde decreasing to 9.5 wt %, finally obtaining the target compound through a series of processes of cooling crystallization, separation and purification, wherein used equipment being shown in FIGURE, and involved chemical reaction equation being as follows,

(7) ##STR00005##

(8) and the molecular formula of obtained 2,2,5,5-tetramethyl-3,4-hexanediol being shown in Formula I

(9) ##STR00006##

(10) with R standing for —H;

(11) (1.2) Synthesizing 2,5,6,6-tetramethyl-2,5-heptanediol

(12) (a) mixing KOH, 3-methyl-3-hydroxybutyne, 3,3-dimethyl-2-butanone and isopropyl ether in the molar ratio of 1:1:1.2:2.0, then carrying out the reaction in an ice bath for 2 hr, finally obtaining octyne diol through a series of processes of cooling crystallization, centrifugation, washing, refining and drying;

(13) (b) mixing octyne diol, alcohol and Pd catalyst in the weight ratio of 2:10:0.01, then carrying out the reaction accompanied with a continuous hydrogen input at 40° C. for 50 min, finally obtaining 2,5,6,6-tetramethyl-2,5-heptanediol through a series of processes of separation and purification, wherein obtained target compound possessing a molecular structure just as shown in Formula II;

(14) ##STR00007##

(15) (1.3) Esterification

(16) concocting terephthalic acid, 1,4-butanediol, 2,2-difluoro-1,3-malonic acid, 2,2,5,5-tetramethyl-3,4-hexanediol and 2,5,6,6-tetramethyl-2,5-heptanediol into a slurry, then adding in titanium dioxide and triphenyl phosphate and carrying out the esterification in a nitrogen atmosphere with a pressure 1 KPa less than the absolute pressure at 180° C., finally ending the reaction when the water distillation reaching 90% of the theoretical value, wherein the molar ratio of terephthalic acid and 1,4-butanediol being 1:1.2, and being relative to the amount of terephthalic acid, the total addition of 2,2-difluoro-1,3-malonic acid, 2,2,5,5-tetramethyl-3,4-hexanediol and 2,5,6,6-tetramethyl-2,5-heptanediol being 4 mol % in a molar ratio of 3:1:3.2, while the additions of titanium dioxide and triphenyl phosphate being 0.25 wt % and 0.03 wt %, respectively;

(17) (1.3) Polycondensation

(18) adding tetrabutyl titanate into the esterification products, then smoothly reducing the pressure to less than 499 Pa within 30 min and carrying out reaction at 250° C. for 30 min, successively, further reducing the pressure to 99 Pa and continuing the reaction at 265° C. for 50 min, wherein the addition of tetrabutyl titanate being 0.04 wt % according to terephthalic acid, and the obtained modified polyester possessing a molecular weight of 30000 Da and a molecular weight distribution index of 2.0;

(19) (2) Spinning Modified Polyester POY

(20) through a technological way including stages of metering, spinneret extruding (at 265° C.), cooling (at 20° C.), oiling, stretching, heat setting and winding (2900 m/min), converting the modified polyester into POY;

(21) (3) Preparing Modified Polyester DTY

(22) converting above POY into DTY through a technological way including stages of guiding, hot stretching (in the first heating chamber at 220° C. and with a draw ratio 1.4), false-twisting, heat setting (in the second heating chamber at 110° C. with an over-feed ratio 3.5%) and winding (at 620 m/min with an over-feed ratio 3.5%).

(23) The wool-like polyester filament, i.e., the DTY obtained hereinabove, possesses the mechanical performance indices of monofilament fineness 1.0 dtex, breaking strength 3.3 cN/dtex, breaking strength CV value 4.8%, elongation at break 30.0%, elongation at break CV value 7.0%, boiling water shrinkage rate 4.0%, oil content 2.0 wt %, interlacing degree 55/m, and crimp ratio 40.0%;

(24) The dyeing process of the wool-like polyester filament obtained hereinabove is described as follows: throwing the filament into a dyeing bath of 2% (o.w.f) of Disperse Red 3B, then heating the bath to 55° C. and holding for 10 min, further increasing the temperature to 100° C. in a rate of 0.8° C./min and holding for 60 min again, finally cooling the bathe to 50° C. and carry out the reductive cleaning for 20 min;

(25) wherein the dye uptake measurement being as follows: drawing 2 mL of the pre-dyeing bathe and the residual bath into two 10 mL volumetric flasks respectively, and for each one, adding in 4 mL acetone to fully dissolve the dye and diluting the solution to 10 mL with distilled water, then measure the absorbance of the diluted solution with a spectrophotometer, finally calculating
dye uptake (%)=(1−A.sub.1)/A.sub.0×100%

(26) with A.sub.0 standing for the absorbance of the pre-dyeing solution, A.sub.1 for the residual one;

(27) wherein the color fastness being tested according to the standards of GB3920-83, GB251-64 and GB3921-83, while the K/S value being directly measured with a SF600X DATACOLOR colorimeter during which the tests being performed 5 times within different wavelength bands and being averaged.

(28) The dyeing performance indices obtained hereinabove of the wool like polyester filament are as following: dye uptake 90.32%, K/S value 22.15, color fastness to soaping level 4, color fastness to dry crocking level 4, and color fastness to wet crocking level 5.

(29) The wool-like polyester filament obtained hereinabove shows an intrinsic viscosity drop by 26% when stored at 25° C. and R.H. 65% for 60 months.

(30) Comparison 1

(31) A method for preparing the wool-like polyester filament involved steps basically the same as those in Example 1, except for no modification for polyester, i.e., there is no 2,2-difluoro-1,3-malonic acid, 2,2,5,5-tetramethyl-3,4-hexanediol and 2,5,6,6-tetramethyl-2,5-heptanediol in step (1), from which the finally obtained wool-like polyester filament possesses

(32) the mechanical performance indices of monofilament fineness 1.0 dtex, breaking strength 3.2 cN/dtex, breaking strength CV value 4.7%, elongation at break 32%, elongation at break CV value 7.0%, boiling water shrinkage rate 4.2%, oil content 2.0 wt %, interlacing degree 55/m, and crimp ratio 40.0%;

(33) the dyeing performance indices of dye uptake 89.78% (dye at 100° C.), K/S value 21.31, color fastness to soaping less than level 4 (level 3-4 under polyester staining while level 3-4 under cotton staining), color fastness to dry crocking level 4, and color fastness to wet crocking level 3-4;

(34) and an intrinsic viscosity drop by 4.8% when stored at 25° C. and R.H. 65% for 60 months.

(35) The comparison shows that the modification herein by means of 2,2-difluoro-1,3-malonic acid, 2,2,5,5-tetramethyl-3,4-hexanediol and 2,5,6,6-tetramethyl-2,5-heptanediol will significantly improve the dyeing and natural degradation performance of polyester fiber without loss of mechanical properties.

(36) Comparison 2

(37) A method for preparing the wool-line polyester filament involved steps basically the same as those in Example 1, except for using 3,3-difluoroglutaric acid instead of 2,2-difluoro-1,3-malonic acid in step (1), from which the finally obtained wool-like polyester filament possesses

(38) the mechanical performance indices of monofilament fineness 1.0 dtex, breaking strength 3.2 cN/dtex, breaking strength CV value 4.6%, elongation at break 32%, elongation at break CV value 7.0%, boiling water shrinkage rate 4.2%, oil content 2.0 wt %, interlacing degree 55/m, and crimp ratio 40.0%;

(39) and an intrinsic viscosity drop by 4.9% when stored at 25° C. and R.H. 65% for 60 months.

(40) The comparison shows that compared with α-C bonded fluorine atom, β-C bonded fluorine atom in the modified polyester can only make rather weak effect upon the natural degradation of the obtained polyester fiber, because its electron-withdrawing effect just pass to the neighbor atoms of β-C so as to give little influence on the nucleophilic addition reaction of ester carbonyl when attacked by OH.sup.−.

(41) Comparison 3

(42) A method for preparing the wool-like polyester filament involved steps basically the same as those in Example 1, except for using 1,2-dodecyl glycol instead of 2,2,5,5-tetramethyl-3,4-hexanediol and 2,5,6,6-tetramethyl-2,5-heptanediol in step (1), from which the finally obtained wool-like polyester filament possesses

(43) the mechanical performance indices of monofilament fineness 1.0 dtex, breaking strength 3.2 cN/dtex, breaking strength CV value 4.7%, elongation at break 31%, elongation at break CV value 7.0%, boiling water shrinkage rate 4.0%, oil content 2.0 wt %, interlacing degree 55/m, and crimp ratio 40.0%;

(44) and the dyeing performance indices of dye uptake 89.98% (at 100° C.), K/S value 21.57, color fastness to soaping level 4-5, color fastness to dry crocking less than level 4 (level 3-4 under polyester staining while level 3-4 under cotton staining), and color fastness to wet crocking level 3-4.

(45) The comparison shows that 2,2,5,5-tetramethyl-3,4-hexanediol and 2,5,6,6-tetramethyl-2,5-heptanediol are more efficient than 1,2-dodecyl glycol on improving the dyeing performances of the wool-like polyester filament, and the reason on one hand is that the short side chain can enlarge the void free volume whereas the long side can mainly enlarge the slit free volume, and the void free volume is more efficient than the slit one for the penetration of dye particles into the fiber, on the other hand, the short side chain with higher rigidity will seldom cause the molecular chain entanglement and gain more free volume in the molecular aggregate.

Example 2

(46) A method for preparing the wool-like polyester filament, comprising the steps:

(47) (1) Preparation of Modified Polyester

(48) (1.1) Synthesizing 2,2,5,5-tetramethyl-3,4-diethyl-3,4-hexanediol

(49) (a) mixing 350 g/L of 2,2-dimethyl-3-pentanone solution and 210 g/L of dilute sulfuric acid solution in the mole ratio 1.6:1 of 2,2-dimethyl-3-pentanone to sulfuric acid at first, and adding the mixture into a electrolytic cell, then cooling the mixed solution to 11° C. and carrying out the electrolytic reduction until the concentration of 2,2-dimethyl-3-pentanone decreasing to 9.0 wt %, finally obtaining the target compound through a series of processes of cooling crystallization, separation and purification, wherein used equipment and involved chemical reaction equation being the same as those in Example 1, and the molecular formula of obtained 2,2,5,5-tetramethyl-3,4-diethyl-3,4-hexanediol being shown in Formula I with R standing for —CH.sub.2CH.sub.3;

(50) (1.2) Synthesizing 2,5,6,6-tetramethyl-2,5-heptanediol

(51) (a) mixing KOH, 3-methyl-3-hydroxybutyne, 3,3-dimethyl-2-butanone and isopropyl ether in the molar ratio of 1.1:1:1.2:2.3, then carrying out the reaction in an ice bath for 2 hr, finally obtaining octyne diol through a series of processes of cooling crystallization, centrifugation, washing, refining and drying;

(52) (b) mixing octyne diol, alcohol and Pd catalyst in the weight ratio of 2:10:0.01, then carrying out the reaction accompanied with a continuous hydrogen input at 45° C. for 50 min, finally obtaining 2,5,6,6-tetramethyl-2,5-heptanediol through a series of processes of separation and purification, wherein obtained target compound possessing a molecular structure just as shown in Formula II;

(53) (1.3) Esterification

(54) concocting terephthalic acid, 1,4-butanediol, 2,2-difluoro-1,4-succinic acid, 2,2,5,5-tetramethyl-3,4-diethyl-3,4-hexanediol and 2,5,6,6-tetramethyl-2,5-heptanediol into a slurry, then adding in titanium dioxide and trimethyl phosphate and carrying out the esterification in a nitrogen atmosphere with a pressure 1 KPa less than the absolute pressure at 180° C., finally ending the reaction when the water distillation reaching 91% of the theoretical value, wherein the molar ratio of terephthalic acid and 1,4-butanediol being 1:2.0, and being relative to the amount of terephthalic acid, the total addition of 2,2-difluoro-1,4-succinic acid, 2,2,5,5-tetramethyl-3,4-diethyl-3,4-hexanediol and 2,5,6,6-tetramethyl-2,5-heptanediol being 3 mol % in a molar ratio of 3:2:3, while the additions of titanium dioxide and trimethyl phosphate being 0.23 wt % and 0.02 wt %, respectively;

(55) (1.3) Polycondensation

(56) adding tetrabutyl titanate into the esterification products, then smoothly reducing the pressure to less than 450 Pa within 50 min and carrying out reaction at 260° C. for 50 min, successively, further reducing the pressure to 90 Pa and continuing the reaction at 265° C. for 70 min, wherein the addition of tetrabutyl titanate being 0.03 wt % according to terephthalic acid, and the obtained modified polyester possessing a molecular weight of 28000 Da and a molecular weight distribution index of 2.2;

(57) (2) Spinning Modified Polyester POY

(58) through a technological way including stages of metering, spinneret extruding (at 265° C.), cooling (at 22° C.), oiling, stretching, heat setting and winding (2800 m/min), converting the modified polyester into POY;

(59) (3) Preparing Modified Polyester DTY

(60) converting above POY into DTY through a technological way including stages of guiding, hot stretching (in the first heating chamber at 215° C. and with a draw ratio 1.5), false-twisting, heat setting (in the second heating chamber at 120° C. with an over-feed ratio 5.5%) and winding (at 620 m/min with an over-feed ratio 2.5%).

(61) The wool-like polyester filament, i.e., the DTY obtained hereinabove, possesses the mechanical performance indices of monofilament fineness 1.5 dtex, breaking strength 3.2 cN/dtex, breaking strength CV value 4.6%, elongation at break 32%, elongation at break CV value 7.5%, boiling water shrinkage rate 4.5%, oil content 2.0 wt %, interlacing degree 70/m, and crimp ratio 44.0%;

(62) The dyeing process of the wool-like polyester filament obtained hereinabove is carried out under the conditions just the same as Example 1, and the dyeing performance indices are as following: dye uptake 90.32%, K/S value 23.42, color fastness to soaping level 4, color fastness to dry crocking level 4, and color fastness to wet crocking level 5.

(63) The wool-like polyester filament obtained hereinabove shows an intrinsic viscosity drop by 19% when stored at 25° C. and R.H. 65% for 60 months.

Example 3

(64) A method for preparing the wool-like polyester filament, comprising the steps:

(65) (1) Preparation of Modified Polyester

(66) (1.1) Synthesizing 2,2,4,4-tetramethyl-3,4-di-tert-butyl-3,4-hexanediol

(67) (a) mixing 340 g/L of 2,2,4,4-tetramethyl-3-pentanone solution and 230 g/L of dilute sulfuric acid solution in the mole ratio 1.7:1 of 2,2,4,4-tetramethyl-3-pentanone to sulfuric acid at first, and adding the mixture into a electrolytic cell, then cooling the mixed solution to 10° C. and carrying out the electrolytic reduction until the concentration of 2,2,4,4-tetramethyl-3-pentanone decreasing to 9.6 wt %, finally obtaining the target compound through a series of processes of cooling crystallization, separation and purification, wherein used equipment and involved chemical reaction equation being the same as those in Example 1, and the molecular formula of obtained 2,2,4,4-tetramethyl-3,4-di-tert-butyl-3,4-hexanediol being shown in Formula I with R standing for —CH(CH.sub.3).sub.3;

(68) (1.2) Synthesizing 2,5,6,6-tetramethyl-2,5-heptanediol

(69) (a) mixing KOH, 3-methyl-3-hydroxybutyne, 3,3-dimethyl-2-butanone and isopropyl ether in the molar ratio of 1.2:1:1.25:2.0, then carrying out the reaction in an ice bath for 2 hr, finally obtaining octyne diol through a series of processes of cooling crystallization, centrifugation, washing, refining and drying;

(70) (b) mixing octyne diol, alcohol and Pd catalyst in the weight ratio of 3:10:0.03, then carrying out the reaction accompanied with a continuous hydrogen input at 40° C. for 50 min, finally obtaining 2,5,6,6-tetramethyl-2,5-heptanediol through a series of processes of separation and purification, wherein obtained target compound possessing a molecular structure just as shown in Formula II;

(71) (1.3) Esterification

(72) concocting terephthalic acid, 1,4-butanediol, 2,2-difluoro-1,5-glutaric acid, 2,2,4,4-tetramethyl-3,4-di-tert-butyl-3,4-hexanediol and 2,5,6,6-tetramethyl-2,5-heptanediol into a slurry, then adding in titanium dioxide and trimethyl phosphite and carrying out the esterification in a nitrogen atmosphere with a pressure 1 KPa less than the absolute pressure at 190° C., finally ending the reaction when the water distillation reaching 93% of the theoretical value, wherein the molar ratio of terephthalic acid and 1,4-butanediol being 1:1.2, and being relative to the amount of terephthalic acid, the total addition of 2,2-difluoro-1,5-glutaric acid, 2,2,4,4-tetramethyl-3,4-di-tert-butyl-3,4-hexanediol and 2,5,6,6-tetramethyl-2,5-heptanediol being 3 mol % in a molar ratio of 3.4:1:3, while the additions of titanium dioxide and triphenyl phosphite being 0.20 wt % and 0.05 wt %, respectively;

(73) (1.3) Polycondensation

(74) adding tetrabutyl titanate into the esterification products, then smoothly reducing the pressure to less than 480 Pa within 40 min and carrying out reaction at 255° C. for 40 min, successively, further reducing the pressure to 95 Pa and continuing the reaction at 268° C. for 50 min, wherein the addition of tetrabutyl titanate being 0.03 wt % according to terephthalic acid, and the obtained modified polyester possessing a molecular weight of 25000 Da and a molecular weight distribution index of 2.4;

(75) (2) Spinning Modified Polyester POY

(76) through a technological way including stages of metering, spinneret extruding (at 267° C.), cooling (at 20° C.), oiling, stretching, heat setting and winding (2800 m/min), converting the modified polyester into POY;

(77) (3) Preparing Modified Polyester DTY

(78) converting above POY into DTY through a technological way including stages of guiding, hot stretching (in the first heating chamber at 200° C. and with a draw ratio 1.43), false-twisting, heat setting (in the second heating chamber at 120° C. with an over-feed ratio 3.5%) and winding (at 620 m/min with an over-feed ratio 2.5%).

(79) The wool-like polyester filament, i.e., the DTY obtained hereinabove, possesses the mechanical performance indices of monofilament fineness 1.8 dtex, breaking strength 3.0 cN/dtex, breaking strength CV value 4.1%, elongation at break 27%, elongation at break CV value 8.0%, boiling water shrinkage rate 5.0%, oil content 3.0 wt %, interlacing degree 60/m, and crimp ratio 36.0%;

(80) The dyeing process of the wool-like polyester filament obtained hereinabove is carried out under the conditions just the same as Example 1, and the dyeing performance indices are as following: dye uptake 92.56%, K/S value 23.42, color fastness to soaping level 4, color fastness to dry crocking level 4, and color fastness to wet crocking level 5.

(81) The wool-like polyester filament obtained hereinabove shows an intrinsic viscosity drop by 20% when stored at 25° C. and R.H. 65% for 60 months.

Example 4

(82) A method for preparing the wool-like polyester filament, comprising the steps:

(83) (1) Preparation of Modified Polyester

(84) (1.1) Synthesizing 2,2,5,5-tetramethyl-3,4-hexanediol

(85) (a) mixing 300 g/L of 2,2-methylpropionaldehyde solution and 250 g/L of dilute sulfuric acid solution in the mole ratio 1.8:1 of 2,2-methylpropionaldehyde to sulfuric acid at first, and adding the mixture into a electrolytic cell, then cooling the mixed solution to 15° C. and carrying out the electrolytic reduction until the concentration of 2,2-methylpropionaldehyde decreasing to 9.3 wt %, finally obtaining the target compound through a series of processes of cooling crystallization, separation and purification, wherein used equipment and involved chemical reaction equation being the same as those in Example 1, and the molecular formula of obtained 2,2,5,5-tetramethyl-3,4-hexanediol being shown in Formula I with R standing for —H;

(86) (1.2) Synthesizing 2,5,6,6-tetramethyl-2,5-heptanediol

(87) (a) mixing KOH, 3-methyl-3-hydroxybutyne, 3,3-dimethyl-2-butanone and isopropyl ether in the molar ratio of 1.2:1:1.3:2.5, then carrying out the reaction in an ice bath for 3 hr, finally obtaining octyne diol through a series of processes of cooling crystallization, centrifugation, washing, refining and drying;

(88) (b) mixing octyne diol, alcohol and Pd catalyst in the weight ratio of 2.5:10:0.02, then carrying out the reaction accompanied with a continuous hydrogen input at 45° C. for 60 min, finally obtaining 2,5,6,6-tetramethyl-2,5-heptanediol through a series of processes of separation and purification, wherein obtained target compound possessing a molecular structure just as shown in Formula II;

(89) (1.3) Esterification

(90) concocting terephthalic acid, 1,4-butanediol, 2,2,3,3-tetrafluoro-1,4-succinic acid, 2,2,5,5-tetramethyl-3,4-hexanediol and 2,5,6,6-tetramethyl-2,5-heptanediol into a slurry, then adding in titanium dioxide and trimethyl phosphite and carrying out the esterification in a nitrogen atmosphere with a pressure 1 KPa less than the absolute pressure at 190° C., finally ending the reaction when the water distillation reaching 93% of the theoretical value, wherein the molar ratio of terephthalic acid and 1,4-butanediol being 1:1.5, and being relative to the amount of terephthalic acid, the total addition of 2,2,3,3-tetrafluoro-1,4-succinic acid, 2,2,5,5-tetramethyl-3,4-hexanediol and 2,5,6,6-tetramethyl-2,5-heptanediol being 5 mol % in a molar ratio of 3.8:1.6:4, while the additions of titanium dioxide and trimethyl phosphite being 0.20 wt % and 0.01 wt %, respectively;

(91) (1.3) Polycondensation

(92) adding tetrabutyl titanate into the esterification products, then smoothly reducing the pressure to less than 480 Pa within 35 min and carrying out reaction at 258° C. for 45 min, successively, further reducing the pressure to 96 Pa and continuing the reaction at 266° C. for 65 min, wherein the addition of tetrabutyl titanate being 0.05 wt % according to terephthalic acid, and the obtained modified polyester possessing a molecular weight of 25000 Da and a molecular weight distribution index of 1.9;

(93) (2) Spinning Modified Polyester POY

(94) through a technological way including stages of metering, spinneret extruding (at 268° C.), cooling (at 21° C.), oiling, stretching, heat setting and winding (3000 m/min), converting the modified polyester into POY;

(95) (3) Preparing Modified Polyester DTY

(96) converting above POY into DTY through a technological way including stages of guiding, hot stretching (in the first heating chamber at 200° C. and with a draw ratio 1.48), false-twisting, heat setting (in the second heating chamber at 110° C. with an over-feed ratio 4.5%) and winding (at 650 m/min with an over-feed ratio 5.0%).

(97) The wool-like polyester filament, i.e., the DTY obtained hereinabove, possesses the mechanical performance indices of monofilament fineness 2.5 dtex, breaking strength 3.0 cN/dtex, breaking strength CV value 4.8%, elongation at break 29%, elongation at break CV value 7.9%, boiling water shrinkage rate 5.5%, oil content 2.5 wt %, interlacing degree 55/m, and crimp ratio 41.0%;

(98) The dyeing process of the wool-like polyester filament obtained hereinabove is carried out under the conditions just the same as Example 1, and the dyeing performance indices are as following: dye uptake 91.85%, K/S value 22.15, color fastness to soaping level 4, color fastness to dry crocking level 4, and color fastness to wet crocking level 6.

(99) The wool-like polyester filament obtained hereinabove shows an intrinsic viscosity drop by 20% when stored at 25° C. and R.H. 65% for 60 months.

Example 5

(100) A method for preparing the wool-like polyester filament, comprising the steps:

(101) (1) Preparation of Modified Polyester

(102) (1.1) Synthesizing 2,2,5,5-tetramethyl-3,4-diethyl-3,4-hexanediol

(103) (a) mixing 310 g/L of 2,2-dimethyl-3-pentanone solution and 300 g/L of dilute sulfuric acid solution in the mole ratio 1.9:1 of 2,2-dimethyl-3-pentanone to sulfuric acid at first, and adding the mixture into a electrolytic cell, then cooling the mixed solution to 15° C. and carrying out the electrolytic reduction until the concentration of 2,2-dimethyl-3-pentanone decreasing to 8.8 wt %, finally obtaining the target compound through a series of processes of cooling crystallization, separation and purification, wherein used equipment and involved chemical reaction equation being the same as those in Example 1, and the molecular formula of obtained 2,2,5,5-tetramethyl-3,4-diethyl-3,4-hexanediol being shown in Formula I with R standing for —CH.sub.2CH.sub.3;

(104) (1.2) Synthesizing 2,5,6,6-tetramethyl-2,5-heptanediol

(105) (a) mixing KOH, 3-methyl-3-hydroxybutyne, 3,3-dimethyl-2-butanone and isopropyl ether in the molar ratio of 1:1:1.3:3.0, then carrying out the reaction in an ice bath for 4 hr, finally obtaining octyne diol through a series of processes of cooling crystallization, centrifugation, washing, refining and drying;

(106) (b) mixing octyne diol, alcohol and Pd catalyst in the weight ratio of 2.5:10:0.02, then carrying out the reaction accompanied with a continuous hydrogen input at 50° C. for 55 min, finally obtaining 2,5,6,6-tetramethyl-2,5-heptanediol through a series of processes of separation and purification, wherein obtained target compound possessing a molecular structure just as shown in Formula II;

(107) (1.3) Esterification

(108) concocting terephthalic acid, 1,4-butanediol, 2,2-difluoro-1,3-malonic acid, 2,2,5,5-tetramethyl-3,4-diethyl-3,4-hexanediol and 2,5,6,6-tetramethyl-2,5-heptanediol into a slurry, then adding in titanium dioxide and triphenyl phosphate and carrying out the esterification in a nitrogen atmosphere with a pressure 1 KPa less than the absolute pressure at 220° C., finally ending the reaction when the water distillation reaching 93% of the theoretical value, wherein the molar ratio of terephthalic acid and 1,4-butanediol being 1:1.8, and being relative to the amount of terephthalic acid, the total addition of 2,2-difluoro-1,3-malonic acid, 2,2,5,5-tetramethyl-3,4-diethyl-3,4-hexanediol and 2,5,6,6-tetramethyl-2,5-heptanediol being 4 mol % in a molar ratio of 4:1.2:3.5, while the additions of titanium dioxide and triphenyl phosphate being 0.25 wt % and 0.01 wt %, respectively;

(109) (1.3) Polycondensation

(110) adding tetrabutyl titanate into the esterification products, then smoothly reducing the pressure to less than 480 Pa within 50 min and carrying out reaction at 255° C. for 50 min, successively, further reducing the pressure to 95 Pa and continuing the reaction at 270° C. for 55 min, wherein the addition of tetrabutyl titanate being 0.04 wt % according to terephthalic acid, and the obtained modified polyester possessing a molecular weight of 30000 Da and a molecular weight distribution index of 1.9;

(111) (2) Spinning Modified Polyester POY

(112) through a technological way including stages of metering, spinneret extruding (at 275° C.), cooling (at 21° C.), oiling, stretching, heat setting and winding (2850 m/min), converting the modified polyester into POY;

(113) (3) Preparing Modified Polyester DTY

(114) converting above POY into DTY through a technological way including stages of guiding, hot stretching (in the first heating chamber at 220° C. and with a draw ratio 1.4), false-twisting, heat setting (in the second heating chamber at 120° C. with an over-feed ratio 4.5%) and winding (at 650 m/min with an over-feed ratio 4.0%).

(115) The wool-like polyester filament, i.e., the DTY obtained hereinabove, possesses the mechanical performance indices of monofilament fineness 3.0 dtex, breaking strength 3.2 cN/dtex, breaking strength CV value 5.0%, elongation at break 26%, elongation at break CV value 7.2%, boiling water shrinkage rate 6.0%, oil content 2.5 wt %, interlacing degree 65/m, and crimp ratio 40.0%;

(116) The dyeing process of the wool-like polyester filament obtained hereinabove is carried out under the conditions just the same as Example 1, and the dyeing performance indices are as following: dye uptake 93.27%, K/S value 23.05, color fastness to soaping level 4, color fastness to dry crocking level 4, and color fastness to wet crocking level 6.

(117) The wool-like polyester filament obtained hereinabove shows an intrinsic viscosity drop by 17% when stored at 25° C. and R.H. 65% for 60 months.

Example 6

(118) A method for preparing the wool-like polyester filament, comprising the steps:

(119) (1) Preparation of Modified Polyester

(120) (1.1) Synthesizing 2,2,4,4-tetramethyl-3,4-di-tert-butyl-3,4-hexanediol

(121) (a) mixing 350 g/L of 2,2,4,4-tetramethyl-3-pentanone solution and 220 g/L of dilute sulfuric acid solution in the mole ratio 2:1 of 2,2,4,4-tetramethyl-3-pentanone to sulfuric acid at first, and adding the mixture into a electrolytic cell, then cooling the mixed solution to 13° C. and carrying out the electrolytic reduction until the concentration of 2,2,4,4-tetramethyl-3-pentanone decreasing to 9.6 wt %, finally obtaining the target compound through a series of processes of cooling crystallization, separation and purification, wherein used equipment and involved chemical reaction equation being the same as those in Example 1, and the molecular formula of obtained 2,2,4,4-tetramethyl-3,4-di-tert-butyl-3,4-hexanediol being shown in Formula I with R standing for —CH(CH.sub.3).sub.3;

(122) (1.2) Synthesizing 2,5,6,6-tetramethyl-2,5-heptanediol

(123) (a) mixing KOH, 3-methyl-3-hydroxybutyne, 3,3-dimethyl-2-butanone and isopropyl ether in the molar ratio of 1.1:1:1.2:3.0, then carrying out the reaction in an ice bath for 4 hr, finally obtaining octyne diol through a series of processes of cooling crystallization, centrifugation, washing, refining and drying;

(124) (b) mixing octyne diol, alcohol and Pd catalyst in the weight ratio of 3:10:0.03, then carrying out the reaction accompanied with a continuous hydrogen input at 50° C. for 60 min, finally obtaining 2,5,6,6-tetramethyl-2,5-heptanediol through a series of processes of separation and purification, wherein obtained target compound possessing a molecular structure just as shown in Formula II;

(125) (1.3) Esterification

(126) concocting terephthalic acid, 1,4-butanediol, 2,2-difluoro-1,4-succinic acid, 2,2,4,4-tetramethyl-3,4-di-tert-butyl-3,4-hexanediol and 2,5,6,6-tetramethyl-2,5-heptanediol into a slurry, then adding in titanium dioxide and trimethyl phosphate and carrying out the esterification in a nitrogen atmosphere with a pressure 1 KPa less than the absolute pressure at 220° C., finally ending the reaction when the water distillation reaching 90% of the theoretical value, wherein the molar ratio of terephthalic acid and 1,4-butanediol being 1:2.0, and being relative to the amount of terephthalic acid, the total addition of 2,2-difluoro-1,4-succinic acid, 2,2,4,4-tetramethyl-3,4-di-tert-butyl-3,4-hexanediol and 2,5,6,6-tetramethyl-2,5-heptanediol being 5 mol % in a molar ratio of 4:2:4, while the additions of titanium dioxide and triphenyl phosphate being 0.21 wt % and 0.01 wt %, respectively;

(127) (1.3) Polycondensation

(128) adding tetrabutyl titanate into the esterification products, then smoothly reducing the pressure to less than 450 Pa within 30 min and carrying out reaction at 260° C. for 30 min, successively, further reducing the pressure to 92 Pa and continuing the reaction at 270° C. for 70 min, wherein the addition of tetrabutyl titanate being 0.05 wt % according to terephthalic acid, and the obtained modified polyester possessing a molecular weight of 28000 Da and a molecular weight distribution index of 1.9;

(129) (2) Spinning Modified Polyester POY

(130) through a technological way including stages of metering, spinneret extruding (at 275° C.), cooling (at 22° C.), oiling, stretching, heat setting and winding (3000 m/min), converting the modified polyester into POY;

(131) (3) Preparing Modified Polyester DTY

(132) converting above POY into DTY through a technological way including stages of guiding, hot stretching (in the first heating chamber at 215° C. and with a draw ratio 1.4), false-twisting, heat setting (in the second heating chamber at 140° C. with an over-feed ratio 5.5%) and winding (at 710 m/min with an over-feed ratio 5.0%).

(133) The wool-like polyester filament, i.e., the DTY obtained hereinabove, possesses the mechanical performance indices of monofilament fineness 2.4 dtex, breaking strength 3.1 cN/dtex, breaking strength CV value 5.0%, elongation at break 28%, elongation at break CV value 7.5%, boiling water shrinkage rate 5.0%, oil content 3.0 wt %, interlacing degree 70/m, and crimp ratio 36.0%;

(134) The dyeing process of the wool-like polyester filament obtained hereinabove is carried out under the conditions just the same as Example 1, and the dyeing performance indices are as following: dye uptake 93.27%, K/S value 23.42, color fastness to soaping level 4, color fastness to dry crocking level 4, and color fastness to wet crocking level 5.

(135) The wool-like polyester filament obtained hereinabove shows an intrinsic viscosity drop by 19% when stored at 25° C. and R.H. 65% for 60 months.

Example 7

(136) A method for preparing the wool-like polyester filament, comprising the steps:

(137) (1) Preparation of Modified Polyester

(138) (1.1) Synthesizing 2,2,5,5-tetramethyl-3,4-hexanediol

(139) (a) mixing 340 g/L of 2,2-methylpropionaldehyde solution and 260 g/L of dilute sulfuric acid solution in the mole ratio 1.5:1 of 2,2-methylpropionaldehyde to sulfuric acid at first, and adding the mixture into a electrolytic cell, then cooling the mixed solution to 13° C. and carrying out the electrolytic reduction until the concentration of 2,2-methylpropionaldehyde decreasing to 9.5 wt %, finally obtaining the target compound through a series of processes of cooling crystallization, separation and purification, wherein used equipment and involved chemical reaction equation being the same as those in Example 1, and the molecular formula of obtained 2,2,5,5-tetramethyl-3,4-hexanediol being shown in Formula I with R standing for —H;

(140) (1.2) Synthesizing 2,5,6,6-tetramethyl-2,5-heptanediol

(141) (a) mixing KOH, 3-methyl-3-hydroxybutyne, 3,3-dimethyl-2-butanone and isopropyl ether in the molar ratio of 1.2:1:1.2:3.0, then carrying out the reaction in an ice bath for 3 hr, finally obtaining octyne diol through a series of processes of cooling crystallization, centrifugation, washing, refining and drying;

(142) (b) mixing octyne diol, alcohol and Pd catalyst in the weight ratio of 3:10:0.02, then carrying out the reaction accompanied with a continuous hydrogen input at 42° C. for 55 min, finally obtaining 2,5,6,6-tetramethyl-2,5-heptanediol through a series of processes of separation and purification, wherein obtained target compound possessing a molecular structure just as shown in Formula II;

(143) (1.3) Esterification

(144) concocting terephthalic acid, 1,4-butanediol, 2,2-difluoro-1,5-glutaric acid, 2,2,5,5-tetramethyl-3,4-hexanediol and 2,5,6,6-tetramethyl-2,5-heptanediol into a slurry, then adding in titanium dioxide and trimethyl phosphite and carrying out the esterification in a nitrogen atmosphere with a pressure 1 KPa less than the absolute pressure at 220° C., finally ending the reaction when the water distillation reaching 93% of the theoretical value, wherein the molar ratio of terephthalic acid and 1,4-butanediol being 1:1.9, and being relative to the amount of terephthalic acid, the total addition of 2,2-difluoro-1,5-glutaric acid, 2,2,5,5-tetramethyl-3,4-hexanediol and 2,5,6,6-tetramethyl-2,5-heptanediol being 4 mol % in a molar ratio of 3.6:1:3.8, while the additions of titanium dioxide and trimethyl phosphite being 0.25 wt % and 0.05 wt %, respectively;

(145) (1.3) Polycondensation

(146) adding tetrabutyl titanate into the esterification products, then smoothly reducing the pressure to less than 490 Pa within 50 min and carrying out reaction at 255° C. for 50 min, successively, further reducing the pressure to 95 Pa and continuing the reaction at 268° C. for 50 min, wherein the addition of tetrabutyl titanate being 0.035 wt % according to terephthalic acid, and the obtained modified polyester possessing a molecular weight of 30000 Da and a molecular weight distribution index of 2.4;

(147) (2) Spinning Modified Polyester POY

(148) through a technological way including stages of metering, spinneret extruding (at 272° C.), cooling (at 20° C.), oiling, stretching, heat setting and winding (2900 m/min), converting the modified polyester into POY;

(149) (3) Preparing Modified Polyester DTY

(150) converting above POY into DTY through a technological way including stages of guiding, hot stretching (in the first heating chamber at 220° C. and with a draw ratio 1.5), false-twisting, heat setting (in the second heating chamber at 140° C. with an over-feed ratio 3.5%) and winding (at 710 m/min with an over-feed ratio 3.5%).

(151) The wool-like polyester filament, i.e., the DTY obtained hereinabove, possesses the mechanical performance indices of monofilament fineness 2.0 dtex, breaking strength 3.1 cN/dtex, breaking strength CV value 4.5%, elongation at break 26%, elongation at break CV value 8.0%, boiling water shrinkage rate 5.0%, oil content 2.5 wt %, interlacing degree 50/m, and crimp ratio 44.0%;

(152) The dyeing process of the wool-like polyester filament obtained hereinabove is carried out under the conditions just the same as Example 1, and the dyeing performance indices are as following: dye uptake 92.55%, K/S value 22.15, color fastness to soaping level 4, color fastness to dry crocking level 4, and color fastness to wet crocking level 5.

(153) The wool-like polyester filament obtained hereinabove shows an intrinsic viscosity drop by 18% when stored at 25° C. and R.H. 65% for 60 months.