FULLY DULL POLYESTER DRAWN YARN AND PREPARING METHOD THEREOF

Abstract

A type of fully dull polyester drawn yarns and a preparing method thereof are disclosed. The preparing method is to melt spinning a modified polyester with the fully drawn yarn (FDY) technique, and the modified polyester is a product of an esterification and successive polycondensation reactions of evenly mixed terephthalic acid, ethylene glycol, 2,5,6,6-tetramethyl-2,5-heptanediol, a fluorinated dicarboxylic acid, a matting agent, a calcined multiphase solid acid base powder and a doped Bi.sub.2O.sub.3 powder. The obtained fiber has an intrinsic viscosity drop of 18-26% when stored at 25 C. and R.H. 65% for 60 months. The method of improving the degradation performance of polyester fiber through the incorporation of 2,5,6,6-tetramethyl-2,5-heptanediol, the fluorinated dicarboxylic acid, the doped Bi.sub.2O.sub.3 powder and the calcined multiphase solid acid base powder is easy to operate.

Claims

1. A preparing method for a fully dull polyester drawn yarn, comprising: manufacturing a fully drawn yarn (FDY) with a modified polyester; wherein the modified polyester is a product of esterification and successive polycondensation reactions of an evenly mixed mixture of terephthalic acid, ethylene glycol, 2,5,6,6-tetramethyl-2,5-heptanediol, a fluorinated dicarboxylic acid, a matting agent, a calcined multiphase solid acid base powder and a doped Bi.sub.2O.sub.3 powder; wherein the 2,5,6,6-tetramethyl-2,5-heptanediol has a molecular formula of ##STR00003## 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 matting agent has an additive amount equal to or larger than 2 wt % of the evenly mixed mixture; wherein the calcined multiphase solid acid base powder is SiO.sub.2Al.sub.2O.sub.3 and/or SiO.sub.2MgO calcined at 400-700 C.; wherein the doped Bi.sub.2O.sub.3 powder is obtained through a process of evenly mixing a Ca.sup.2+ solution and a Bi.sup.3+ solution to form an evenly mixed solution, then adding a precipitant to the evenly mixed solution until pH=9-10 to obtain a precipitate, and finally calcining the precipitate.

2. The preparing method of claim 1, wherein the Ca.sup.2+ solution is an aqueous one with a concentration of 2-3%, an anion in the Ca.sup.2+ solution is NO.sub.3.sup.; wherein the Bi.sup.3+ solution is a product of dissolving 20-25 wt % of Bi.sub.2O.sub.3 in nitric acid; wherein the precipitant is ammonia water with a concentration of 2 mol/L; wherein the evenly mixed solution has a (5-8):100 molar ratio of Ca.sup.2+ with respective to Bi.sup.3+ before precipitation; wherein the calcining is a high temperature treatment for 2-4 hrs; wherein the SiO.sub.2Al.sub.2O.sub.3 or SiO.sub.2MgO has a SiO.sub.2 content of 20-60 wt % and an average size of less than 0.5 micron after the calcining.

3. The preparing method of claim 2, 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 a first 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 at a weight ratio of (2-3):10:(0.01-0.03), then carrying out a second reaction accompanied 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.

4. The preparing method of claim 3, wherein the modified polyester is manufactured through following steps: (1) Esterification concocting the terephthalic acid, the ethylene glycol, the 2,5,6,6-tetramethyl-2,5-heptanediol and the fluorinated dicarboxylic acid into a slurry, then adding the calcined multiphase solid acid base powder, the doped Bi.sub.2O.sub.3 powder, a catalyst, the matting agent and a stabilizer in the slurry and carrying out the esterification in a nitrogen atmosphere with a pressure of normal value-0.3 MPa at 250-260 C., and finally ending the esterification when a water distillation rate reaches more than 90% of a theoretical value; (2) Polycondensation for products of the esterification, smoothly reducing the pressure to less than 500 Pa (absolute value) within 30-50 min and carrying out the successive polycondensation reactions at 250-260 C. for 30-50 min, further reducing the pressure to less than 100 Pa (absolute value) and continuing the successive polycondensation reactions at 270-282 C. for 50-90 min.

5. The preparing method of claim 4, wherein a molar ratio of the terephthalic acid and the ethylene glycol is 1:(1.2-2.0), and a total addition of the 2,5,6,6-tetramethyl-2,5-heptanediol and the fluorinated dicarboxylic acid is 3-5 mol % of an amount of the terephthalic acid, a molar ratio of the 2,5,6,6-tetramethyl-2,5-heptanediol and the fluorinated dicarboxylic acid is 2-3:3-4, while an amount of the calcined multiphase solid acid base powder, the doped Bi.sub.2O.sub.3 powder, the catalyst, the matting agent and the stabilizer are 0.03-0.05 wt %, 0.04-0.07 wt %, 0.03-0.05 wt %, 2-3 wt % and 0.01-0.05 wt % of the amount of the terephthalic acid, respectively.

6. The preparing method of claim 5, wherein the catalyst is selected from the group consisting of antimony trioxide, ethylene glycol antimony and antimony acetate, wherein the matting agent is titanium dioxide, and wherein the stabilizer is selected from the group consisting of triphenyl phosphate, trimethyl phosphate and trimethyl phosphite.

7. The preparing method claim 6, wherein the modified polyester has a molecular weight of 25000-30000 and a molecular weight distribution index of 1.8-2.2.

8. The preparing method of claim 1, wherein a FDY technique process includes the steps of metering, spinneret extruding, cooling, oiling, stretching, heat setting and winding; wherein the FDY process involves the following parameters: a spinning temperature of 285-295 C., a cooling temperature of 20-25 C., an interlacing pressure of 0.20-0.30 MPa, a first godet roller speed of 1600-1800 m/min, a first godet roller temperature of 70-80 C., a second godet roller speed of 3000-3200 m/min, a second godet roller temperature of 105-130 C., a winding speed of 2950-3130 m/min.

9. A fully dull polyester drawn yarn prepared by the preparing method of claim 1, comprising: a modified polyester FDY; wherein the modified polyester has a molecular chain structure composed of terephthalic acid segments, ethylene glycol segments, 2,5,6,6-tetramethyl-2,5-heptanediol segments and fluorinated dicarboxylic acid segments; wherein the modified polyester is dispersed with the matting agent, the doped Bi.sub.2O.sub.3 powder and the calcined multiphase solid acid base powder, and a content of the matting agent is equal to or larger than 2 wt %.

10. The fully dull polyester drawn yarn of claim 9, wherein the fully dull polyester drawn yan has mechanical performance indices of a monofilament fineness 1.0-3.0 dtex, a breaking strength 2.0 cN/dtex, an elongation at break 42.04.0%, an interlacing degree 194/m, a linear density deviation rate 1.0%, a breaking strength CV value %, a breaking elongation CV value 10.0%, and a boiling water shrinkage rate 50.010.5%; and has an intrinsic viscosity drop of 18-25% after a storage at 25 C. and R.H. 65% for 60 months.

11. The fully dull polyester drawn yarn of claim 9, wherein wherein the Ca.sup.2+ solution is an aqueous one with a concentration of 2-3%, an anion in the Ca.sup.2+ solution is NO.sub.3.sup.; wherein the Bi.sup.3+ solution is a product of dissolving 20-25 wt % of Bi.sub.2O.sub.3 in nitric acid; wherein the precipitant is ammonia water with a concentration of 2 mol/L; wherein the evenly mixed solution has a (5-8):100 molar ratio of Ca.sup.2+with respective to Bi.sup.3+ before precipitation; wherein the calcining is a high temperature treatment for 2-4 hrs; wherein the SiO.sub.2Al.sub.2O.sub.3 or SiO.sub.2MgO has a SiO.sub.2 content of 20-60 wt % and an average size of less than 0.5 micron after the calcining.

12. The fully dull polyester drawn yarn of claim 11, 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 a first 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 at a weight ratio of (2-3):10:(0.01-0.03), then carrying out a second reaction accompanied 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.

13. The fully dull polyester drawn yarn of claim 12, wherein the modified polyester is manufactured through following steps: (1) Esterification concocting the terephthalic acid, the ethylene glycol, the 2,5,6,6-tetramethyl-2,5-heptanediol and the fluorinated dicarboxylic acid into a slurry, then adding the calcined multiphase solid acid base powder, the doped Bi.sub.2O.sub.3 powder, a catalyst, the matting agent and a stabilizer in the slurry and carrying out the esterification in a nitrogen atmosphere with a pressure of normal value-0.3 MPa at 250-260 C., and finally ending the esterification when a water distillation rate reaches more than 90% of a theoretical value; (2) Polycondensation for products of the esterification, smoothly reducing the pressure to less than 500 Pa (absolute value) within 30-50 min and carrying out the successive polycondensation reactions at 250-260 C. for 30-50 min, further reducing the pressure to less than 100 Pa (absolute value) and continuing the successive polycondensation reactions at 270-282 C. for 50-90 min.

14. The fully dull polyester drawn yarn of claim 13, wherein a molar ratio of the terephthalic acid and the ethylene glycol is 1:(1.2-2.0), and a total addition of the 2,5,6,6-tetramethyl-2,5-heptanediol and the fluorinated dicarboxylic acid is 3-5 mol % of an amount of the terephthalic acid, a molar ratio of the 2,5,6,6-tetramethyl-2,5-heptanediol and the fluorinated dicarboxylic acid is 2-3:3-4, while an amount of the calcined multiphase solid acid base powder, the doped Bi.sub.2O.sub.3 powder, the catalyst, the matting agent and the stabilizer are 0.03-0.05 wt%, 0.04-0.07 wt %, 0.03-0.05 wt %, 2-3 wt % and 0.01-0.05 wt % of the amount of the terephthalic acid, respectively.

15. The fully dull polyester drawn yarn of claim 14, wherein the catalyst is selected from the group consisting of antimony trioxide, ethylene glycol antimony and antimony acetate, wherein the matting agent is titanium dioxide, and wherein the stabilizer is selected from the group consisting of triphenyl phosphate, trimethyl phosphate and trimethyl phosphite.

16. The fully dull polyester drawn yarn of claim 15, wherein the modified polyester has a molecular weight of 25000-30000 and a molecular weight distribution index of 1.8-2.2.

17. The fully dull polyester drawn yarn of claim 9, wherein a FDY process includes the steps of metering, spinneret extruding, cooling, oiling, stretching, heat setting and winding; wherein the FDY process involves the following parameters: a spinning temperature of 285-295 C., a cooling temperature of 20-25 C., an interlacing pressure of 0.20-0.30 MPa, a first godet roller speed of 1600-1800 m/min, a first godet roller temperature of 70-80 C., a second godet roller speed of 3000-3200 m/min, a second godet roller temperature of 105-130 C., a winding speed of 2950-3130 m/min.

Description

DETAILED DESCRIPTION OF THE EMBODIMENTS

[0069] 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

[0070] A method for preparing the fully dull polyester drawn yarns, comprising the steps:

[0071] (1) Preparation of modified polyester

[0072] (1.1) Preparation of multiphase solid acid base SiO.sub.2Al.sub.2O.sub.3

[0073] adding 4 wt % of disperser PEG 6000 into a sodium silicate solution with an SiO.sub.2 equivalent concentration of 12 wt % and stirring the mixture at 45 C. till be soluble, then evenly adding in 12 wt % of sulfuric acid solution till pH=10, after aging for 1.0 hr continuing to add in sulfuric acid solution till pH=8, heating the solution to 95 C. and aging for 2 hr, then filtering the solution under vacuum and washing the residue with water until no SO4.sup.2 detection then further washing with anhydrous ethanol for several times, finally drying the product at 80 C. and grinding it to obtain silica powder;

[0074] adding 1 part of above silica powder into 55 parts of water and stirring to disperse, then dripping in 2 parts of aluminum sulfate solution with a weight concentration of 4.5%, adjusting the pH value firstly to neutral and then to 8 with 0.5 mol/L sodium hydroxide solution and 8% sulfuric acid successively, after aging for 2 hr filtering the solution under vacuum and washing the residue until no SO4.sup.2 detection, further washing the filter cake with anhydrous ethanol for several times and then drying it at 100 C., finally calcining the product at 500 C. for 3 hr to obtain solid acid base SiO.sub.2Al.sub.2O.sub.3 with an average size of 0.4 micron and a silica content of 40 wt %;

[0075] (1.2) Doping modification of Bi.sub.2O.sub.3

[0076] (1.2.1) evenly mixing a 2.5 wt % of Ca(NO.sub.3).sub.2 aqueous solution and a 22 wt % of Bi.sub.2O.sub.3 nitric acid solution in 7:100 molar ratio of Ca.sup.2+ and Bi.sup.3+;

[0077] (1.2.2) depositing the mixed solution by adding 2 mol/L of ammonia water till pH=10, then washing and drying (105 C., 2.5 hr) the precipitate;

[0078] (1.2.3) after the treatment composed of a heating at 400 C. for 2.5 hr, a heating at 700 C. for 1.5 hr and a cooling in air, crushing the precipitate to doped Bi.sub.2O.sub.3 powder with an average size of 0.45 micron;

[0079] (1.3) Synthesizing 2,5,6,6-tetramethyl-2,5-heptanediol

[0080] (1.3.1) 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;

[0081] (1.3.2) 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 I;

##STR00002##

[0082] (1.4) Esterification

[0083] concocting terephthalic acid, ethylene glycol, 2,5,6,6-tetramethyl-2,5-heptanediol and 2,2-difluoro-1,3-malonic acid into a slurry, then adding in multiphase solid acid base SiO.sub.2Al.sub.2O.sub.3, doped Bi.sub.2O.sub.3, antimony trioxide, titanium dioxide and triphenyl phosphate and carrying out the esterification in a nitrogen atmosphere with a pressure of 0.3 MPa at 250 C., finally ending the reaction when the water distillation reaching 90.1% of the theoretical value, wherein the molar ration of terephthalic acid and ethylene glycol is 1:1.2, and being relative to the amount of terephthalic acid, the total addition of 2,5,6,6-tetramethyl-2,5-heptanediol and 2,2-difluoro-1,3-malonic acid is 3 mol % in a molar ratio of 2:3, while the addition of multiphase solid acid base SiO.sub.2Al.sub.2O.sub.3, doped Bi.sub.2O.sub.3, antimony trioxide, titanium dioxide and triphenyl phosphate are 0.03 wt %, 0.04 wt %, 0.03 wt %, 2 wt % and 0.01 wt %, respectively;

[0084] (1.5) Polycondensation

[0085] for the esterification products, smoothly reducing the pressure to 499 Pa (absolute value) within 30 min and carrying out reaction at 250 C. for 30 min, successively, further reducing the pressure to 99 Pa (absolute value) and continuing the reaction at 270 C. for 50 min, finally obtaining the modified polyester with a molecular weight of 25000 and a molecular weight distribution index of 1.8;

[0086] (2) Spinning of Fully Dull Polyester Drawn Yarn

[0087] through a FDY technological way including stages of metering, spinneret extruding (at 285 C.), cooling (at 20 C.), oiling, stretching as well as heat setting (carried on with the parameters of interlacing pressure 0.20 MPa, godet roller 1 speed 1600 m/min, godet roller 1 temperature 70 C., godet roller 2 speed 3000 m/min, godet roller 2 temperature 105 C.), and winding (2950 m/min), converting the modified polyester into fully dull polyester drawn yarns.

[0088] Finally obtained fully dull polyester yarn has an intrinsic viscosity drop of 18% after stored at 25 C. and R.H. 65% for 60 months, and the other property indices are listed in Table 1.

[0089] Comparison 1

[0090] A method for preparing the fully dull polyester drawn yarns involved steps basically the same as those in Example 1, except for no addition of 2,5,6,6-tetramethyl-2,5-heptanediol, 2,2-difluoro-1,3-malonic acid, multiphase solid acid base SiO.sub.2Al.sub.2O.sub.3 and doped Bi.sub.2O.sub.3 in step (1), from which the finally obtained fully dull polyester drawn yarn has an intrinsic viscosity drop of 4.8% after stored at 25 C. and R.H. 65% for 60 months, and the other property indices are listed in Table 1.

[0091] Comparison 2

[0092] A method for preparing the fully dull polyester drawn yarns involved steps basically the same as those in Example 1, except for no addition of 2,5,6,6-tetramethyl-2,5-heptanediol in step (1), from which the finally obtained fully dull polyester drawn yarn has an intrinsic viscosity drop of 12.6% after stored at 25 C. and R.H. 65% for 60 months, and the other property indices are listed in Table 1.

[0093] Comparison 3

[0094] A method for preparing the fully dull polyester drawn yarns involved steps basically the same as those in Example 1, except for no addition of 2,2-difluoro-1,3-malonic acid in step (1), from which the finally obtained fully dull polyester drawn yarn has an intrinsic viscosity drop of 11.1% after stored at 25 C. and R.H. 65% for 60 months, and the other property indices are listed in Table 1.

[0095] Comparison 4

[0096] A method for preparing the fully dull polyester drawn yarns involved steps basically the same as those in Example 1, except for no addition of doped Bi.sub.2O.sub.3 in step (1), from which the finally obtained fully dull polyester drawn yarn has an intrinsic viscosity drop of 12.7% after stored at 25 C. and R.H. 65% for 60 months, and the other property indices are listed in Table 1.

[0097] Comparison 5

[0098] A method for preparing the fully dull polyester drawn yarns involved steps basically the same as those in Example 1, except for no addition of multiphase solid acid base SiO.sub.2Al.sub.2O.sub.3 in step (1), from which the finally obtained fully dull polyester drawn yarn has an intrinsic viscosity drop of 13.2% after stored at 25 C. and R.H. 65% for 60 months, and the other property indices are listed in Table 1.

[0099] Based on the comparative analysis between Example 1 and Comparison 1-5, it could be found that the incorporation of addition of 2,5,6,6-tetramethyl-2,5-heptanediol, 2,2-difluoro-1,3-malonic acid, multiphase solid acid base SiO.sub.2Al.sub.2O.sub.3 and doped Bi.sub.2O.sub.3 will significantly improve the natural degradation performance of polyester fiber, in which doped Bi.sub.2O.sub.3 increases the conductivity of oxygen ion and the oxygen reduction extent, 2,2-difluoro-1,3-malonic acid reduces the electron cloud density of CO bond, solid acid base SiO.sub.2Al.sub.2O.sub.3 releases nucleophilic ion OH.sup., and 2,5,6,6-tetramethyl-2,5-heptanediol enlarges the free volume favorable to the penetration of air and wafter. All those effects can promote the nucleophilic addition involved in polyester hydrolysis and synergistically improve the degradation polyester without decaying the processibility and mechanical property of the fiber.

[0100] Comparison 6

[0101] A method for preparing the fully dull polyester drawn yarn involved steps basically the same as those in Example 1, except for using 1,2-dodecyl glycol instead of 2,5,6,6-tetramethyl-2,5-heptanediol in step (1), from which the finally obtained fully dull polyester yarn possesses the mechanical performance indices of monofilament fineness 2.95 dtex, breaking strength 2.2 cN/dtex, elongation at break 45.1%, interlacing degree 22/m, linear density deviation rate 0.82%, breaking strength CV value 6.5%, breaking elongation CV value 10.4%, and boiling water shrinkage rate 40.5%, as well as an intrinsic viscosity drop of 13.7% after stored at 25 C. and R.H. 65% for 60 months

[0102] The comparison with Example 1 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

[0103] A method for preparing the fully dull polyester drawn yarns, comprising the steps:

[0104] (1) Preparation of modified polyester

[0105] (1.1) Preparation of multiphase solid acid base SiO.sub.2MgO

[0106] adding 3 wt % of disperser PEG 6000 into a sodium silicate solution with an SiO.sub.2 equivalent concentration of 10 wt % and stirring the mixture at 40 C. till be soluble, then evenly adding in 10 wt % of sulfuric acid solution till pH=10, after aging for 0.5 hr continuing to add in sulfuric acid solution till pH=8, heating the solution to 90 C. and aging for 2 hr, then filtering the solution under vacuum and washing the residue with water until no SO4.sup.2 detection then further washing with anhydrous ethanol for several times, finally drying the product at 80 C. and grinding it to obtain silica powder;

[0107] adding 1 part of above silica powder into 50 parts of water and stirring to disperse, then dripping in 3 parts of magnesium sulfate solution with a weight concentration of 4%, adjusting the pH value firstly to neutral and then to 8 with 0.5 mol/L sodium hydroxide solution and 8% sulfuric acid successively, after aging for lhr filtering the solution under vacuum and washing the residue until no SO4.sup.2 detection, further washing the filter cake with anhydrous ethanol for several times and then drying it at 100 C., finally calcining the product at 400 C. for 4 hr to obtain solid acid base SiO.sub.2MgO with an average size of 0.4 micron and a silica content of 20 wt %;

[0108] (1.2) Doping modification of Bi.sub.2O.sub.3

[0109] (1.2.1) evenly mixing a 2 wt % of Ca(NO.sub.3).sub.2 aqueous solution and a 20 wt % of Bi.sub.2O.sub.3 nitric acid solution in 5:100 molar ratio of Ca.sup.2+ and Bi.sup.3+;

[0110] (1.2.2) depositing the mixed solution by adding 2 mol/L of ammonia water till pH=9, then washing and drying (105 C., 2 hr) the precipitate;

[0111] (1.2.3) after the treatment composed of a heating at 400 C. for 2 hr, a heating at 700 C. for 1 hr and a cooling in air, crushing the precipitate to doped Bi.sub.2O.sub.3 powder with an average size of 0.4 micron;

[0112] (1.3) Synthesizing 2,5,6,6-tetramethyl-2,5-heptanediol

[0113] (1.3.1) 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;

[0114] (1.3.2) 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 I;

[0115] (1.4) Esterification

[0116] concocting terephthalic acid, ethylene glycol, 2,5,6,6-tetramethyl-2,5-heptanediol and 2,2-difluoro-1,4-succinic acid into a slurry, then adding in multiphase solid acid base SiO.sub.2MgO, doped Bi.sub.2O.sub.3, ethylene glycol antimony, titanium dioxide and trimethyl phosphate and carrying out the esterification in a nitrogen atmosphere with a pressure of normal value at 260 C., finally ending the reaction when the water distillation reaching 95% of the theoretical value, wherein the molar ration of terephthalic acid and ethylene glycol is 1:2.0, and being relative to the amount of terephthalic acid, the total addition of 2,5,6,6-tetramethyl-2,5-heptanediol and 2,2-difluoro-1,4-succinic acid is 5 mool % in a molar ratio of 3:4, while the addition of multiphase solid acid base SiO.sub.2MgO, doped Bi.sub.2O.sub.3, ethylene glycol antimony, titanium dioxide and trimethyl phosphate are 0.05 wt %, 0.07 wt %, 0.05 wt %, 3 wt % and 0.05 wt %, respectively;

[0117] (1.5) Polycondensation

[0118] for the esterification products, smoothly reducing the pressure to 450 Pa (absolute value) within 50 min and carrying out reaction at 260 C. for 50 min, successively, further reducing the pressure to 90 Pa (absolute value) and continuing the reaction at 282 C. for 90 min, finally obtaining the modified polyester with a molecular weight of 30000 and a molecular weight distribution index of 2.2;

[0119] (2) Spinning of fully dull polyester drawn yarn

[0120] through a FDY technological way including stages of metering, spinneret extruding (at 295 C.), cooling (at 25 C.), oiling, stretching as well as heat setting (carried on with the parameters of interlacing pressure 0.30 MPa, godet roller 1 speed 1800 m/min, godet roller 1 temperature 80 C., godet roller 2 speed 3200 m/min, godet roller 2 temperature 130 C.), and winding (3130 m/min), converting the modified polyester into fully dull polyester drawn yarns.

[0121] Finally obtained fully dull polyester yarn has an intrinsic viscosity drop of 25% after stored at 25 C. and R.H. 65% for 60 months, and the other property indices are listed in Table 1.

Example 3

[0122] A method for preparing the fully dull polyester drawn yarns, comprising the steps:

[0123] (1) Preparation of modified polyester

[0124] (1.1) Preparation of multiphase solid acid base SiO.sub.2Al.sub.2O.sub.3

[0125] adding 3 wt % of disperser PEG 6000 into a sodium silicate solution with an SiO.sub.2 equivalent concentration of 10 wt % and stirring the mixture at 40 C. till be soluble, then evenly adding in 10 wt % of sulfuric acid solution till pH=10, after aging for 0.5 hr continuing to add in sulfuric acid solution till pH=8, heating the solution to 90 C. and aging for 2 hr, then filtering the solution under vacuum and washing the residue with water until no SO4.sup.2 detection then further washing with anhydrous ethanol for several times, finally drying the product at 85 C. and grinding it to obtain silica powder;

[0126] adding 1 part of above silica powder into 60 parts of water and stirring to disperse, then dripping in 2 parts of aluminum sulfate solution with a weight concentration of 4%, adjusting the pH value firstly to neutral and then to 8 with 1.0 mol/L sodium hydroxide solution and 10% sulfuric acid successively, after aging for 2 hr filtering the solution under vacuum and washing the residue until no SO4.sup.2 detection, further washing the filter cake with anhydrous ethanol for several times and then drying it at 100 C., finally calcining the product at 700 C. for 2 hr to obtain solid acid base SiO.sub.2Al.sub.2O.sub.3 with an average size of 0.4 micron and a silica content of 60 wt %;

[0127] (1.2) Doping modification of Bi.sub.2O.sub.3

[0128] (1.2.1) evenly mixing a 3 wt % of Ca(NO.sub.3).sub.2 aqueous solution and a 25 wt % of Bi.sub.2O.sub.3 nitric acid solution in 8:100 molar ratio of Ca.sup.2+ and Bi.sup.3+;

[0129] (1.2.2) depositing the mixed solution by adding 2 mol/L of ammonia water till pH=9, then washing and drying (110 C., 3 hr) the precipitate;

[0130] (1.2.3) after the treatment composed of a heating at 400 C. for 3 hr, a heating at 700 C. for 2 hr and a cooling in air, crushing the precipitate to doped Bi.sub.2O.sub.3 powder with an average size of 0.4 micron;

[0131] (1.3) Synthesizing 2,5,6,6-tetramethyl-2,5-heptanediol

[0132] (1.3.1) 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 3 hr, finally obtaining octyne diol through a series of processes of cooling crystallization, centrifugation, washing, refining and drying;

[0133] (1.3.2) 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 I;

[0134] (1.4) Esterification

[0135] concocting terephthalic acid, ethylene glycol, 2,5,6,6-tetramethyl-2,5-heptanediol and 2,2-difluoro-1,5-glutaric acid into a slurry, then adding in multiphase solid acid base SiO.sub.2Al.sub.2O.sub.3, doped Bi.sub.2O.sub.3, antimony acetate, titanium dioxide and trimethyl phosphite and carrying out the esterification in a nitrogen atmosphere with a pressure of 0.2 MPa at 255 C., finally ending the reaction when the water distillation reaching 92% of the theoretical value, wherein the molar ration of terephthalic acid and ethylene glycol is 1:1.6, and being relative to the amount of terephthalic acid, the total addition of 2,5,6,6-tetramethyl-2,5-heptanediol and 2,2-difluoro-1,5-glutaric acid is 4 mol % in a molar ratio of 2:4, while the addition of multiphase solid acid base SiO.sub.2Al.sub.2O.sub.3, doped Bi.sub.2O.sub.3, antimony acetate, titanium dioxide and trimethyl phosphite are 0.04 wt %, 0.055 wt %, 0.04 wt %, 2.5 wt % and 0.03 wt %, respectively;

[0136] (1.5) Polycondensation

[0137] for the esterification products, smoothly reducing the pressure to 480 Pa (absolute value) within 40 min and carrying out reaction at 255 C. for 40 min, successively, further reducing the pressure to 95 Pa (absolute value) and continuing the reaction at 276 C. for 70 min, finally obtaining the modified polyester with a molecular weight of 27000 and a molecular weight distribution index of 2.0;

[0138] (2) Spinning of fully dull polyester drawn yarn

[0139] through a FDY technological way including stages of metering, spinneret extruding (at 290 C.), cooling (at 22 C.), oiling, stretching as well as heat setting (carried on with the parameters of interlacing pressure 0.25 MPa, godet roller 1 speed 1700 m/min, godet roller 1 temperature 75 C., godet roller 2 speed 3100 m/min, godet roller 2 temperature 118 C.), and winding (3030 m/min), converting the modified polyester into fully dull polyester drawn yarns.

[0140] Finally obtained fully dull polyester yarn has an intrinsic viscosity drop of 21% after stored at 25 C. and R.H. 65% for 60 months, and the other property indices are listed in Table 1.

Example 4

[0141] A method for preparing the fully dull polyester drawn yarns, comprising the steps:

[0142] (1) Preparation of modified polyester

[0143] (1.1) Preparation of multiphase solid acid base SiO.sub.2MgO

[0144] adding 4 wt % of disperser PEG 6000 into a sodium silicate solution with an SiO.sub.2 equivalent concentration of 14 wt % and stirring the mixture at 45 C. till be soluble, then evenly adding in 13 wt % of sulfuric acid solution till pH=10, after aging for 1.0 hr continuing to add in sulfuric acid solution till pH=8, heating the solution to 95 C. and aging for 2 hr, then filtering the solution under vacuum and washing the residue with water until no SO4.sup.2 detection then further washing with anhydrous ethanol for several times, finally drying the product at 85 C. and grinding it to obtain silica powder;

[0145] adding 1 part of above silica powder into 57 parts of water and stirring to disperse, then dripping in 2 parts of magnesium sulfate solution with a weight concentration of 4%, adjusting the pH value firstly to neutral and then to 8 with 0.8 mol/L sodium hydroxide solution and 9% sulfuric acid successively, after aging for 1.5 hr filtering the solution under vacuum and washing the residue until no SO4.sup.2 detection, further washing the filter cake with anhydrous ethanol for several times and then drying it at 100 C., finally calcining the product at 600 C. for 4 hr to obtain solid acid base SiO.sub.2MgO with an average size of 0.4 micron and a silica content of 45 wt %;

[0146] (1.2) Doping modification of Bi.sub.2O.sub.3

[0147] (1.2.1) evenly mixing a 2.5 wt % of Ca(NO.sub.3).sub.2 aqueous solution and a 25 wt % of Bi.sub.2O.sub.3 nitric acid solution in 8:100 molar ratio of Ca.sup.2+ and Bi.sup.3+;

[0148] (1.2.2) depositing the mixed solution by adding 2 mol/L of ammonia water till pH=10, then washing and drying (110 C., 3 hr) the precipitate;

[0149] (1.2.3) after the treatment composed of a heating at 400 C. for 2.5 hr, a heating at 700 C. for 2 hr and a cooling in air, crushing the precipitate to doped Bi.sub.2O.sub.3 powder with an average size of 0.4 micron;

[0150] (1.3) Synthesizing 2,5,6,6-tetramethyl-2,5-heptanediol

[0151] (1.3.1) 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;

[0152] (1.3.2) 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 I;

[0153] (1.4) Esterification

[0154] concocting terephthalic acid, ethylene glycol, 2,5,6,6-tetramethyl-2,5-heptanediol and 2,2,3,3-tetrafluoro-1,4-succinic acid into a slurry, then adding in multiphase solid acid base SiO.sub.2MgO, doped Bi.sub.2O.sub.3, ethylene glycol antimony, titanium dioxide and triphenyl phosphate and carrying out the esterification in a nitrogen atmosphere with a pressure of 0.25 MPa at 250 C., finally ending the reaction when the water distillation reaching 94% of the theoretical value, wherein the molar ration of terephthalic acid and ethylene glycol is 1:1.9, and being relative to the amount of terephthalic acid, the total addition of 2,5,6,6-tetramethyl-2,5-heptanediol and 2,2,3,3-tetrafluoro-1,4-succinic acid is 5 mol % in a molar ratio of 2.5:3.5, while the addition of multiphase solid acid base SiO.sub.2MgO, doped Bi.sub.2O.sub.3, ethylene glycol antimony, titanium dioxide and triphenyl phosphate are 0.03 wt %, 0.04 wt %, 0.03 wt %, 2 wt % and 0.05 wt %, respectively;

[0155] (1.5) Polycondensation

[0156] for the esterification products, smoothly reducing the pressure to 480 Pa (absolute value) within 35 min and carrying out reaction at 258 C. for 45 min, successively, further reducing the pressure to 96 Pa (absolute value) and continuing the reaction at 270 C. for 55 min, finally obtaining the modified polyester with a molecular weight of 26000 and a molecular weight distribution index of 1.9;

[0157] (2) Spinning of fully dull polyester drawn yarn

[0158] through a FDY technological way including stages of metering, spinneret extruding (at 285 C.), cooling (at 25 C.), oiling, stretching as well as heat setting (carried on with the parameters of interlacing pressure 0.25 MPa, godet roller 1 speed 1800 m/min, godet roller 1 temperature 75 C., godet roller 2 speed 3100 m/min, godet roller 2 temperature 105 C.), and winding (2950 m/min), converting the modified polyester into fully dull polyester drawn yarns.

[0159] Finally obtained fully dull polyester yarn has an intrinsic viscosity drop of 18% after stored at 25 C. and R.H. 65% for 60 months, and the other property indices are listed in Table 1.

Example 5

[0160] A method for preparing the fully dull polyester drawn yarns, comprising the steps:

[0161] (1) Preparation of modified polyester

[0162] (1.1) Preparation of multiphase solid acid base SiO.sub.2MgO

[0163] adding 5 wt % of disperser PEG 6000 into a sodium silicate solution with an SiO.sub.2 equivalent concentration of 15wt% and stirring the mixture at 45 C. till be soluble, then evenly adding in 10 wt % of sulfuric acid solution till pH=10, after aging for 1.0 hr continuing to add in sulfuric acid solution till pH=8, heating the solution to 95 C. and aging for 2 hr, then filtering the solution under vacuum and washing the residue with water until no SO4.sup.2 detection then further washing with anhydrous ethanol for several times, finally drying the product at 85 C. and grinding it to obtain silica powder;

[0164] adding 1 part of above silica powder into 59 parts of water and stirring to disperse, then dripping in 2 parts of magnesium sulfate solution with a weight concentration of 4%, adjusting the pH value firstly to neutral and then to 8 with 0.7 mol/L sodium hydroxide solution and 10% sulfuric acid successively, after aging for 2 hr filtering the solution under vacuum and washing the residue until no SO4.sup.2 detection, further washing the filter cake with anhydrous ethanol for several times and then drying it at 100 C., finally calcining the product at 650 C. for 3.5 hr to obtain solid acid base SiO.sub.2MgO with an average size of 0.45 micron and a silica content of 51 wt %;

[0165] (1.2) Doping modification of Bi.sub.2O.sub.3

[0166] (1.2.1) evenly mixing a 2.5 wt % of Ca(NO.sub.3).sub.2 aqueous solution and a 24 wt % of Bi.sub.2O.sub.3 nitric acid solution in 6:100 molar ratio of Ca.sup.2+ and Bi.sup.3+;

[0167] (1.2.2) depositing the mixed solution by adding 2 mol/L of ammonia water till pH=10, then washing and drying (107 C., 2.5 hr) the precipitate;

[0168] (1.2.3) after the treatment composed of a heating at 400 C. for 2.5 hr, a heating at 700 C. for 2 hr and a cooling in air, crushing the precipitate to doped Bi.sub.2O.sub.3 powder with an average size of 0.45 micron;

[0169] (1.3) Synthesizing 2,5,6,6-tetramethyl-2,5-heptanediol

[0170] (1.3.1) 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;

[0171] (1.3.2) 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 I;

[0172] (1.4) Esterification

[0173] concocting terephthalic acid, ethylene glycol, 2,5,6,6-tetramethyl-2,5-heptanediol and 2,2-difluoro-1,3-malonic acid into a slurry, then adding in multiphase solid acid base SiO.sub.2MgO, doped Bi.sub.2O.sub.3, antimony acetate, titanium dioxide and triphenyl phosphate and carrying out the esterification in a nitrogen atmosphere with a pressure of 0.15 MPa at 260 C., finally ending the reaction when the water distillation reaching 96% of the theoretical value, wherein the molar ration of terephthalic acid and ethylene glycol is 1:2.0, and being relative to the amount of terephthalic acid, the total addition of 2,5,6,6-tetramethyl-2,5-heptanediol and 2,2-difluoro-1,3-malonic acid is 3 mol % in a molar ratio of 2:4, while the addition of multiphase solid acid base SiO.sub.2MgO, doped Bi.sub.2O.sub.3, ethylene glycol antimony, titanium dioxide and triphenyl phosphate are 0.04 wt %, 0.05 wt %, 0.04 wt %, 3 wt % and 0.04 wt %, respectively;

[0174] (1.5) Polycondensation

[0175] for the esterification products, smoothly reducing the pressure to 480 Pa (absolute value) within 50 min and carrying out reaction at 255 C. for 50 min, successively, further reducing the pressure to 95 Pa (absolute value) and continuing the reaction at 282 C. for 80 min, finally obtaining the modified polyester with a molecular weight of 29000 and a molecular weight distribution index of 2.1;

[0176] (2) Spinning of fully dull polyester drawn yarn

[0177] through a FDY technological way including stages of metering, spinneret extruding (at 285 C.), cooling (at 25 C.), oiling, stretching as well as heat setting (carried on with the parameters of interlacing pressure 0.25 MPa, godet roller 1 speed 1800 m/min, godet roller 1 temperature 75 C., godet roller 2 speed 3100 m/min, godet roller 2 temperature 105 C.), and winding (2950 m/min), converting the modified polyester into fully dull polyester drawn yarns.

[0178] Finally obtained fully dull polyester yarn has an intrinsic viscosity drop of 18% after stored at 25 C. and R.H. 65% for 60 months, and the other property indices are listed in Table 1.

Example 6

[0179] A method for preparing the fully dull polyester drawn yarns, comprising the steps:

[0180] (1) Preparation of modified polyester

[0181] (1.1) Doping modification of Bi.sub.2O.sub.3

[0182] (a) evenly mixing a 3 wt % of Ca(NO.sub.3).sub.2 aqueous solution and a 24 wt % of Bi.sub.2O.sub.3 nitric acid solution, maintaining a 7:100 of molar ratio of Ca.sup.2+ and Bi.sup.3+;

[0183] (b) depositing the mixed solution by adding 2 mol/L of ammonia water until pH value reaches 10, then washing and drying (110 C., 2.5 hr) the precipitate;

[0184] (c) after the treatment composed of a heating at 400 C. for 3 hr, a heating at 700 C. for 1.5 hr and a cooling in air, crushing the precipitate to doped Bi.sub.2O.sub.3 powder with an average size of 0.45 m;

[0185] (1.2) Esterification

[0186] concocting terephthalic acid, ethylene glycol, tetramethyldisiloxane diol and 2,2-difluoro-1,4-succinic acid into a slurry (in which the molar ration of terephthalic acid and ethylene glycol is 1:2.0, the total addition of tetramethyldisiloxane diol and 2,2-difluoro-1,4-succinic acid with a molar ratio of 3:5 is 4.5 mol % relative to the amount of terephthalic acid), and adding in 0.07 wt % of the doped Bi.sub.2O.sub.3, 0.04 wt % of antimony trioxide, 0.20 wt % of titanium dioxide and 0.05 wt % of trimethyl phosphite (all are relative to the amount of terephthalic acid), then carrying out the esterification in nitrogen under a normal pressure at 260 C., finally ending the reaction when the water distillation rate reaches 91% of the theoretical value;

[0187] (1.3) Polycondensation

[0188] after smoothly reducing the pressure from normal value to 450 Pa within 35 min, conducting the low vacuum polycondensation for the esterification products at 270 C. for 50 min, then further reducing the pressure to 100 Pa and continuing the high vacuum polycondensation at 275 C. for 85 min, finally obtaining the modified polyester with a molecular weight of 27800 and a molecular weight distribution index of 1.8;

[0189] (2) Spinning of fully dull polyester drawn yarn

[0190] through a FDY technological way including stages of metering, spinneret extruding (at 295 C.), cooling (at 18 C.), oiling, stretching as well as heat setting (carried on with the parameters of interlacing pressure 0.20 MPa, godet roller 1 speed 2300 m/min, godet roller 1 temperature 80 C., godet roller 2 speed 4400 m/min, godet roller 2 temperature 130 C.), and winding (4420 m/min), converting the modified polyester into fully dull polyester drawn yarns

[0191] with the mechanical performance indices of monofilament fineness 2.5 dtex, breaking strength 3.5 cN/dtex, elongation at break 33.0%, interlacing degree 11/m, linear density deviation rate 1.0%, breaking strength CV value 5.0%, breaking elongation CV value 8.2%, and boiling water shrinkage rate 6.5%;

[0192] with the dyeing performance indices of dye uptake 91.8% (at 120 C.), K/S value 25.56, color fastness to soaping level 5, color fastness to dry crocking level 5, and color fastness to wet crocking level 6;

[0193] and with an intrinsic viscosity drop by 22% when stored at 25 C. and R.H. 65% for 60 months.

Example 7

[0194] A method for preparing the fully dull polyester drawn yarns, comprising the steps:

[0195] (1) Preparation of modified polyester

[0196] (1.1) Doping modification of Bi.sub.2O.sub.3

[0197] (a) evenly mixing a 2.5 wt % of Ca(NO.sub.3).sub.2 aqueous solution and a 25 wt % of Bi.sub.2O.sub.3 nitric acid solution, maintaining a 8:100 of molar ratio of Ca.sup.2+ and Bi.sup.3+;

[0198] (b) depositing the mixed solution by adding 2 mol/L of ammonia water until pH value reaches 10, then washing and drying (110 C., 3 hr) the precipitate;

[0199] (c) after the treatment composed of a heating at 400 C. for 3 hr, a heating at 700 C. for 2 hr and a cooling in air, crushing the precipitate to doped Bi.sub.2O.sub.3 powder with an average size of 0.45 m;

[0200] (1.2) Esterification

[0201] concocting terephthalic acid, ethylene glycol, tetramethyldisiloxane diol and 2,2-difluoro-1,5-glutaric acid into a slurry (in which the molar ration of terephthalic acid and ethylene glycol is 1:1.3, the total addition of tetramethyldisiloxane diol and 2,2-difluoro-1,5-glutaric acid with a molar ratio of 2.5:3 is 5 mol % relative to the amount of terephthalic acid), and adding in 0.06 wt % of the doped Bi.sub.2O.sub.3, 0.04 wt % of antimony trioxide, 0.21 wt % of titanium dioxide and 0.01 wt % of trimethyl phosphate (all are relative to the amount of terephthalic acid), then carrying out the esterification under a 0.3 MPa of nitrogen pressure at 260 C., finally ending the reaction when the water distillation rate reaches 99% of the theoretical value;

[0202] (1.3) Polycondensation

[0203] after smoothly reducing the pressure from normal value to 500 Pa within 45 min, conducting the low vacuum polycondensation for the esterification products at 280 C. for 50 min, then further reducing the pressure to 90 Pa and continuing the high vacuum polycondensation at 277 C. for 90 min, finally obtaining the modified polyester with a molecular weight of 30000 and a molecular weight distribution index of 2.2;

[0204] (2) Spinning of fully dull polyester drawn yarn

[0205] through a FDY technological way including stages of metering, spinneret extruding (at 295 C.), cooling (at 22 C.), oiling, stretching as well as heat setting (carried on with the parameters of interlacing pressure 0.30 MPa, godet roller 1 speed 2700 m/min, godet roller 1 temperature 86 C., godet roller 2 speed 4500 m/min, godet roller 2 temperature 135 C.), and winding (4130 m/min), converting the modified polyester into fully dull polyester drawn yarns

[0206] with the mechanical performance indices of monofilament fineness 1.2 dtex, breaking strength 3.5 cN/dtex, elongation at break 32.0%, interlacing degree 13/m, linear density deviation rate 0.88%, breaking strength CV value 4.5%, breaking elongation CV value 9.0%, and boiling water shrinkage rate 7.0%;

[0207] with the dyeing performance indices of dye uptake 87.5% (at 120 C.), K/S value 23.55, color fastness to soaping level 5, color fastness to dry crocking level 5, and color fastness to wet crocking level 6;

[0208] and with an intrinsic viscosity drop by 26% when stored at 25 C. and R.H. 65% for 60 months.