TW201420633A - Copolymerized polyester and polyester fiber formed from same - Google Patents

Abstract

The present invention provides: a copolymerized polyester which has high moisture absorption characteristics, while maintaining excellent characteristics of a polyester; and a polyester fiber which is formed from this copolymerized polyester and has excellent moisture absorption. A copolymerized polyester of the present invention is a copolymerized polyester which is obtained by copolymerizing 10-25% by weight of a polyethylene glycol having a number average molecular weight of 8,000-20,000 and comprises ethylene terephthalate as a main repeating unit, and which is characterized by having an amorphous structure that is mainly formed of a polyethylene glycol, while having a polyethylene terephthalate coexistent with the polyethylene glycol.

Description

Copolymerized polyester and polyester fiber composed thereof

The present invention relates to a hygroscopic copolymerized polyester and a polyester fiber composed thereof. More specifically, the present invention relates to a copolymerizable polyester which can be separately spun and which has excellent hygroscopicity and a polyester fiber excellent in hygroscopicity.

Conventionally, polyesters such as polyethylene terephthalate are excellent in strength, thermal stability, and chemical resistance, and are widely used for applications such as fibers, films, and molded articles. However, since polyethylene terephthalate is inherently hydrophobic and extremely hygroscopic, it is used as a clothing to generate a "sweet feeling" when the humidity is high, or to generate static when the humidity is low in winter. Comfort is not the ideal material. Further, when polyethylene terephthalate is used as a resin or a film, there is a problem that it is charged due to low hygroscopicity.

In order to solve such problems, there has been proposed a method of copolymerizing a diol having an oxygen-alkylene glycol on a polyester side chain (refer to Patent Document 1), and copolymerizing a dicarboxylic acid containing a sulfonic acid metal salt. A method of copolymerizing a compound having hygroscopic property into a polyester, such as a method of polyester (refer to Patent Document 2). However, since the entire surface of the polyester polymer is modified by copolymerizing the moisture absorbing component to the polyester, there is a problem that the polyester having the so-called excellent mechanical properties originally has an advantage.

Further, there has been proposed a method in which acrylic acid or methacrylic acid is graft-polymerized to a polyester fiber, and further, after graft polymerization, an alkali metal is substituted for the carboxyl group to impart hygroscopicity (see Patent Document 3). However, this proposal has not yet reached practical use due to problems such as a decrease in light resistance, a slippage due to adhesion of a moisture absorbing component to a composition or a fiber surface layer, or a decrease in strength over time.

Further, in the method of imparting hygroscopicity in the post-fiber processing stage, there are various problems in dyeing or the obtained fiber fabric characteristics. Therefore, in order to provide hygroscopicity at the stage of fiber production and to solve the problem, there has been proposed a core-sheath type composite fiber in which a hygroscopic resin having high hygroscopicity is used as a core portion and coated with a sheath of polyester ( Refer to Patent Documents 4 to 8.). However, in the core-sheath type composite fiber, when the hot-water treatment such as refining or dyeing is performed, the hygroscopic resin of the core is largely swollen with water, and cracks (sheath cracking) occur on the surface of the fiber. There is a problem that the quality of the fabric is lowered when the hygroscopic resin flows out to the outside or the dyeing fastness is remarkably deteriorated.

In order to suppress the cracking of the sheath, it is proposed to provide a hollow portion adjacent to the absorbent core component from the melt spinning stage in advance (see Patent Documents 9 and 10). However, in the case where the fiber is formed into a cross-sectional shape having a hollow portion as in the proposal, in the case where the fiber is subjected to the twisting process or the false twisting process, the hollow portion is crushed in the relevant step due to the subsequent hot water treatment. As in the case described above, there is a problem that the hygroscopic polymer swells and sheath cracking occurs.

[Previous Technical Literature] [Patent Literature]

[Patent Document 1] Japanese Patent Laid-Open No. 48-8270

[Patent Document 2] Japanese Patent Laid-Open No. Hei 2-26985

[Patent Document 3] Japanese Patent Laid-Open No. 52-74020

[Patent Document 4] Japanese Patent Laid-Open No. Hei 2-99612

[Patent Document 5] Japanese Patent Laid-Open No. Hei 4-361616

[Patent Document 6] Japanese Patent Laid-Open No. 4-341617

[Patent Document 7] Japanese Patent Laid-Open No. Hei 8-198954

[Patent Document 8] Japanese Patent Laid-Open No. Hei 9-132871

[Patent Document 9] Japanese Patent Laid-Open No. Hei 9-111579

[Patent Document 10] Japanese Patent Laid-Open No. 52-55721

Accordingly, an object of the present invention is to provide a copolymerized polyester and a polyester fiber excellent in hygroscopicity composed of the copolymerized polyester, which overcomes the above-mentioned problems of the prior art while maintaining the original polyester. Excellent characteristics and high hygroscopic properties on one side.

The present invention solves the above problems, and the copolymerized polyester of the present invention is a main repeating unit in which 10 to 25 wt% of polyethylene glycol having a number average molecular weight of 8,000 to 20,000 is copolymerized as a total of ethylene terephthalate. A polymerized polyester having a copolymerized polyester mainly comprising polyethylene glycol and having an amorphous structure of polyethylene glycol and polyethylene terephthalate.

According to a preferred embodiment of the copolymerized polyester according to the present invention, the above-mentioned mainly comprises polyethylene glycol coexisting with polyethylene glycol and polyterephthalic acid. The amorphous structure of ethylene diester has a polyethylene glycol ratio of 70 to 99% by weight.

According to a preferred embodiment of the copolymerized polyester of the present invention, the copolymerized polyester of the present invention is set to 5 minutes by a DSC (Wide Differential Scanning Calorimeter) at a temperature increase rate of 16 ° C /min to 300 ° C. After the constant temperature state, the mixture was rapidly cooled, and when the temperature was raised to 300 ° C at a temperature increase rate of 16 ° C /min, the melting peak observed in the range of 200 ° C or more was present in the copolymerized polyester in the range of 251 to 260 ° C.

According to a preferred embodiment of the copolymerized polyester of the present invention, the hygroscopic parameter ΔMR of the copolymerized polyester of the present invention is from 2 to 10%.

In the present invention, a polyester fiber excellent in hygroscopicity can be obtained from the copolymerized polyester.

According to the present invention, a copolymerized polyester can be obtained which maintains an excellent characteristic of the polyester on one side and has high hygroscopic properties on one side. The copolymerized polyester of the present invention has high hygroscopicity and can be spun separately, and the obtained polyester fiber can be suitably used as a knitted fabric composed of a monofilament, and is used as a comfortable material for underwear, sportswear, and lining. .

[Formation of the Invention]

The copolymerized polyester of the present invention is a copolymerized polyester of ethylene terephthalate in which the main repeating unit of 10 to 25 wt% of polyethylene glycol having a number average molecular weight of 8,000 to 20,000 is copolymerized.

In the present invention, the main repeating unit is para-xylene. The polyester of the ethylene glycol diester is a polyester which is an acid component of terephthalic acid, such an ester-forming derivative, and ethylene glycol which is a diol component as a main component. Preferably, among all the diol components, ethylene glycol accounts for 80 mol% or more, and more preferably 90 mol% or more of the polyester. In the range which does not impair the effects of the present invention, for example, cyclohexanedimethanol, butanediol, neopentyl glycol, and diethyl diol which are diol components other than ethylene glycol can be copolymerized in a range of 20 mol% or less. Glycol and the like.

In order to impart hygroscopicity to the copolymerized polyester of the present invention, it is necessary to copolymerize polyethylene glycol.

In the polyethylene glycol used in the present invention as a copolymerization component, it is important that the number average molecular weight is from 8,000 to 20,000. The number average molecular weight is determined by the terminal basis quantification method. The terminal basis quantitative method is a method of determining the molecular weight from the integral ratio of the terminal group of the NMR to the main chain.

The present invention is found in a copolymerized polyester comprising polyethylene glycol and polyethylene terephthalate, and it has been found that the hygroscopic property is made extremely large by making polyethylene glycol a specific number average molecular weight. Specifically, the moisture absorption performance is made extremely large by using polyethylene glycol having a number average molecular weight of 8,000 or more. Although the reason is not clear, it is considered that when the number average molecular weight of the polyethylene glycol is 8000 or more, the polyethylene glycol and the polyethylene terephthalate in the polymer form a specific structure to make moisture absorption. Performance is extremely high.

Further, when the number average molecular weight of the polyethylene glycol exceeds 20,000, the reactivity with polyethylene terephthalate is lowered to deteriorate the spinning property, or the polyethylene glycol is eluted in hot water.

From the formability of copolymerized polyester, especially the viewpoint of silkiness The number average molecular weight of the polyethylene glycol is preferably 15,000 or less, and more preferably 10,000 or less.

In the copolymerized polyester of the present invention, the copolymerization ratio of polyethylene glycol must be 10 to 25% by weight. When the copolymerization ratio of polyethylene glycol is less than 10% by weight, the hygroscopicity of the copolymerized polyester is not obtained, and the hygroscopicity is as high as that of the polyester which is not copolymerized with polyethylene glycol. Moreover, from the viewpoint of melt moldability, for example, from the viewpoint of yarn-forming property, the copolymerization ratio of polyethylene glycol must be 25% by weight or less. If the copolymerization ratio exceeds 25% by weight, the use in a high temperature region or the mechanical strength of the obtained molded article tends to be lowered. Moreover, when it is used for the production of a fiber, there is a problem that it cannot be used as a monofilament.

By setting the copolymerization ratio of the polyethylene glycol to 25% by weight or less and improving the spinnability, the spinning speed can be accelerated, the productivity can be improved, and the fine fine fiber can be further obtained. The copolymerization ratio of polyethylene glycol is more preferably 20% by weight or less, still more preferably 15% by weight or less.

In the case of copolymerizing polyethylene terephthalate with polyethylene glycol, the obtained copolymerization is carried out except for an amorphous structure containing polyethylene glycol and an amorphous structure containing polyethylene terephthalate. The polyester also has an amorphous structure in which polyethylene terephthalate and polyethylene glycol coexist.

Further, in an amorphous structure in which polyethylene terephthalate and polyethylene glycol coexist, a polyethylene terephthalate mainly containing polyethylene terephthalate and polyethylene glycol are formed. The amorphous structure of the diol and the amorphous structure mainly comprising polyethylene glycol and polyethylene glycol and polyethylene terephthalate. In the copolymerized polyester of the present invention, among the amorphous structures, it is necessary to have coexistence of polyethylene glycol mainly comprising polyethylene glycol. Amorphous structure of diol and polyethylene terephthalate.

In the present invention, the hygroscopic property is increased by having an amorphous structure mainly comprising polyethylene glycol and polyethylene terephthalate, and the spinning property is further improved. The formability becomes good.

The amorphous structure mainly comprising polyethylene glycol coexisting with polyethylene glycol and polyethylene terephthalate, and is capable of measuring the glass transition temperature by using temperature-modulated differential scanning calorimetry (TM-DSC). Learned. Specifically, it was measured by the following method.

After the copolymerized polyester was melted at a temperature of 290 ° C, it was sufficiently cooled in water at a temperature of 25 ° C. The cooled copolymerized polyester was dried at 25 ° C to remove moisture adhering to the surface to obtain a measurement sample. The DSC signal was separated into a reversible component and an irreversible component by measuring the phase shift behavior of the sample obtained by TM-DSC in a temperature range of -85 to 300 ° C, a temperature increase rate of 2 ° C/min, and a nitrogen atmosphere. The glass transition temperature can be observed by a reversible component.

If it is confirmed that the glass transition temperature measured by TM-DSC is higher than the glass transition temperature (-67 ° C) of polyethylene glycol, and it is 0 ° C or less, it can be confirmed that there is a coexistence of polyethylene glycol mainly containing polyethylene glycol. Amorphous structure of diol and polyethylene terephthalate.

Further, in the present invention, the amorphous structure mainly comprising polyethylene glycol and polyethylene terephthalate is contained in the polyethylene glycol, and if the ratio of the polyethylene glycol is 70% by weight or more, the moisture absorption property It is further elevated to be a preferred form. The proportion of polyethylene glycol is more preferably 80% by weight or more.

Moreover, in the present invention, the coexistence of polyethylene glycol is mainly contained. There is an amorphous structure of polyethylene glycol and polyethylene terephthalate. When the ratio of polyethylene glycol (PEG) is 99% by weight or less, it can be used as a monofilament when used for producing fibers. The polyethylene glycol ratio is more preferably 90% by weight or less.

The ratio of polyethylene glycol coexisting with polyethylene glycol having an amorphous structure of polyethylene glycol and polyethylene terephthalate is determined by temperature-modulated differential scanning calorimetry (TM-DSC). The glass transition temperature (T _{g, obs} (unit: K)), the temperature from the glass transition can be calculated according to Couchman's formula (Formula 1).

(wherein, the X _PET system mainly comprises a weight fraction of polyethylene terephthalate in an amorphous structure in which polyethylene glycol and polyethylene terephthalate coexist, X _PEG The system mainly comprises a polyethylene glycol having a weight fraction of polyethylene glycol in an amorphous structure in which polyethylene glycol and polyethylene terephthalate coexist, and X _PET =1-X _PEG is established. △C _p, difference in heat capacity before and after glass transfer of polyethylene polyethylene terephthalate monomer (△C _{p, PET} =0.4052Jg ^-1 K ^-1 ), △C _{p, PEG-} based polyethylene glycol The difference in heat capacity before and after glass transfer (△C _{p, PEG} = 0.8672Jg ^-1 K ^-1 ), T _g, glass transition temperature of _PET polyethylene terephthalate monomer (T _{g, PET} = 342K ), T _{g, PEG} is the glass transition temperature (T _{g, PEG} = 206 K) of the polyethylene glycol monomer.

The copolymerized polyester of the present invention is a copolymerized polyester having high heat resistance and excellent hygroscopicity, and is melt-formed and is suitable for use in fibers and films. The molded article or the like can be suitably used as a raw material for synthetic fibers. In this case, the hygroscopic parameter (?MR) is preferably 2% or more because of sufficient hygroscopicity. The moisture absorption parameter (ΔMR) is more preferably 4% or more. Further, when the hygroscopic parameter of the copolymerized polyester is 10% or less, the spinnability or the stretchability tends to be good, which is a preferred embodiment.

Here, the hygroscopic parameter (ΔMR) means that the sample which has been humidified and stabilized in a standard state of 20° C.×65% RH is moved to a high-humidity state of 30° C.×90% RH, and the weight after 24 hours. The amount of increase (g) is divided by the value (%) of the absolute dry weight (g) of the sample. Here, the absolute dry weight (g) means a sample weight which is dried at a temperature of 105 ° C and dried until no weight change is observed.

In the copolymerized polyester of the present invention, a pigment such as titanium oxide or carbon black, a surfactant such as an alkylbenzenesulfonate, an antioxidant, an anti-coloring agent, and light resistance can be added to the extent that the object of the present invention is not impaired. Agents, antistatic agents, etc.

The copolymerized polyester of the present invention is produced by a polymerization method such as a transesterification method or an esterification method. In the transesterification method, after the terephthalic acid ester-forming derivative and ethylene glycol are added to the reaction vessel, the reaction is carried out at a temperature of 150 to 250 ° C in the presence of a transesterification catalyst. The stabilizer and the polymerization catalyst are added, and the mixture is heated to a temperature of 260 to 300 ° C under a reduced pressure of 500 Pa or less, and allowed to react for 3 to 5 hours to obtain a copolymerized polyester.

Further, in the esterification method, esterification reaction is carried out at a temperature of 150 to 260 ° C under pressure of nitrogen by adding terephthalic acid and ethylene glycol to the reaction vessel, after the esterification reaction is completed. , adding stabilizer The copolymerized polyester or the like can be obtained by heating to a temperature of 260 to 300 ° C under a reduced pressure of 500 Pa or less and reacting for 3 to 5 hours.

In the production of the copolymerized polyester of the present invention, as the addition period of the polyethylene glycol, it may be added together with other raw materials before the esterification reaction or the transesterification reaction, and also in the esterification reaction or ester. After the end of the exchange reaction, it is added before the start of the polymerization reaction, and the latter is a better form.

In the present invention, the polyethylene glycol having a number average molecular weight of 8,000 or more can be obtained in a solid state such as a sheet or a powder. When polyethylene glycol is added, it is added in a molten state by heating to a temperature of 70 ° C or higher, and is sufficiently dispersed before the start of depressurization of the polycondensation reaction, and polyethylene glycol becomes easy to be paired with polyethylene. By reacting ethylene phthalate, the obtained copolymerized polyester can have an amorphous structure mainly comprising polyethylene glycol and having polyethylene glycol and polyethylene terephthalate, and the hygroscopic property becomes high.

Further, the obtained copolymerized polyester can improve the spinnability, accelerate the spinning speed, and improve the productivity even if it is a single-type fiber, and further obtain a fine-denier fiber, which is a preferred embodiment.

Examples of the transesterification catalyst used in the production of the copolymerized polyester of the present invention include zinc acetate, manganese acetate, magnesium acetate, and titanium tetrabutoxide. Moreover, as a catalyst for polymerization, antimony trioxide, cerium oxide, etc. are mentioned.

The copolymerized polyester of the present invention can be specifically obtained by the following method.

After cooling the oligomer of bis-β-hydroxyethyl terephthalate obtained by the esterification reaction (hereinafter referred to as BHT), it is made into a solid state. It was pulverized to obtain powdery BHT. After thoroughly mixing the powdery BHT and the powdery polyethylene glycol, the mixture is added to a polycondensation reaction apparatus, and while being stirred, it is melted at a temperature of 250 to 270 °C. By adding a stabilizer and a polymerization catalyst or the like to the molten BHT and polyethylene glycol mixture, the mixture is heated to a temperature of 260 to 300 ° C under a reduced pressure of 500 Pa or less, and allowed to react for 3 to 5 hours. A copolymerized polyester is obtained.

Further, after the BHT is synthesized by using a transesterification reaction apparatus or an esterification reaction apparatus, the BHT is transferred to the polycondensation reaction apparatus through the transfer tube from the reaction apparatuses, and the molten polyethylene is injected by way of the transfer tube. The diol was slightly agitated by a polycondensation reaction apparatus to slightly disperse the polyethylene glycol. Thereafter, by adding a stabilizer and a polymerization catalyst or the like to the molten BHT and polyethylene glycol mixture, the mixture is heated to a temperature of 260 to 300 ° C under a reduced pressure of 500 Pa or less to carry out a reaction for 3 to 5 hours. A copolymerized polyester can be obtained. At this time, the filter is placed in the transfer tube, and if polyethylene glycol is injected before the BHT is about to pass through the filter, the polyethylene glycol is easily dispersed in the BHT by the filter on the middle of the transfer tube.

The copolymerized polyester of the present invention can be formed into various resin molded articles by a molding method such as extrusion molding, blow molding, vacuum molding, or injection molding. In particular, when the copolymerized polyester is fiberized by melt spinning, moisture absorption performance is easily exhibited, which is a preferable form.

As the fiber using the copolymerized polyester of the present invention, it is preferred that 20 to 100% by weight of the entire fiber to be formed is the copolymerized polyester of the present invention. When the copolymerized polyester of the present invention is less than 20% by weight, the effect of improving the moisture absorption and desorption property is hardly observed. Further, from the viewpoint of sufficient moisture absorption and desorption, it is preferably 50 to 100 of the total fiber. The weight % is composed of the copolymerized polyester of the present invention.

In particular, the fiber (100%) is composed of the copolymerized polyester of the present invention, that is, the fiber is substantially made into a single fiber, and the hygroscopicity of the fiber can be maximized.

Further, in the conventional core-sheath type composite fiber, there is a problem that the sheath is cracked due to swelling due to moisture absorption, but the fiber composed of the copolymerized polyester of the present invention is used as a monofilament, and the like. The problem has also been solved. Further, by using the fiber composed of the copolymerized polyester of the present invention as a monofilament, since the copolymerized polyester is exposed to the surface, there is an effect of increasing the moisture absorption rate.

The hygroscopicity of the fibers composed of the copolymerized polyester of the present invention is an important criterion for determining the comfort of clothes when it is hot. When the fabric is formed, the hygroscopic parameter (?MR) is preferably 2.0% or more in order to impart comfort. Further, from the viewpoint of comfort, the moisture absorption parameter (?MR) is preferably 4.0% or more. However, if the hygroscopicity parameter of the fiber composed of the copolymerized polyester exceeds 20%, it affects the properties of the fiber. For example, the strength is lowered or the light resistance is deteriorated, and it may become unsuitable for use in the use of clothing or the like. The moisture absorption parameter is preferably 10% or less.

The fiber composed of the copolymerized polyester of the present invention preferably has a single fiber fineness of 10 dtex or less from the viewpoint of the use of the clothing which is suitable for considering hygroscopicity. The single yarn fineness is preferably 5 dtex or less. Further, in the present invention, it is possible to obtain a fiber having a finer single-filament fineness, and it is also possible to obtain a fiber of 1 dtex or less.

The fiber composed of the copolymerized polyester of the present invention can be produced by a melt spinning step. Specifically, from heating to 280 to 300 ° C The temperature of the spinning nozzle melts and extrudes the copolymerized polyester of the present invention. The strands extruded from the spinning nozzle are usually taken up after being cooled and cooled.

Further, the spinning speed is capable of generating molecular orientation by setting it as 500 m/min to 10000 m/min, and improving the workability in the step of the subsequent stretching step.

Further, the process of the fiber composed of the copolymerized polyester of the present invention may be suitably carried out by temporarily winding the spun yarn, stretching the yarn using a stretching machine, or not temporarily spinning the spun yarn. The thread of the yarn, and the procedure of the direct spinning stretching method of the continuous spinning step.

[Examples]

A. moisture absorption parameter (△MR):

3 g of the measurement sample was prepared, and the absolute dry weight (Wd) thereof was measured. The sample was allowed to stand in a constant temperature and humidity machine (LHU-123 manufactured by ESPEC) which had been humidified to 20 ° C × 65% RH for 24 hours, and the weight of the sample (W20) in an equilibrium state was measured, followed by constant temperature and humidity. The setting of the machine was changed to 30 ° C × 90% RH, and the weight (W30) after standing for 24 hours was further measured, and the moisture absorption parameter was determined according to the following formula I.

. Hygroscopic parameter (△MR)=(W30-W20)/Wd(%)...Form I

B. Glass transition temperature, PEG ratio:

Temperature-amplitude differential scanning calorimetry (TM-DSC) was used to determine the temperature observed in the reversible component when the temperature was raised at a rate of 2 ° C/min from a temperature of -85 ° C to 300 ° C in a nitrogen atmosphere. Glass transition temperature below °C.

. Device: DSC Q1000 manufactured by TA Instruments

. Data Analysis: Universal Analysis 2000 by TA Instruments

Further, from the obtained glass transition temperature, the PEG ratio was calculated by the following (Formula 1).

(wherein, the X _PET system mainly comprises a weight fraction of polyethylene terephthalate in an amorphous structure in which polyethylene glycol and polyethylene terephthalate coexist, X _PEG The system mainly comprises a polyethylene glycol having a weight fraction of polyethylene glycol in an amorphous structure in which polyethylene glycol and polyethylene terephthalate coexist, and X _PET = 1 - x _PEG is established. △C _p, difference in heat capacity before and after glass transfer of polyethylene polyethylene terephthalate monomer (△C _{p, PET} =0.4052Jg ^-1 K ^-1 ), △C _{p, PEG-} based polyethylene glycol The difference in heat capacity before and after glass transfer (△C _{p, PEG} = 0.8672Jg ^-1 K ^-1 ), T _g, glass transition temperature of _PET polyethylene terephthalate monomer (T _{g, PET} = 342K ), T _{g, PEG} is the glass transition temperature (T _{g, PEG} = 206 K) of the polyethylene glycol monomer.

C. Spinning:

The mixture was vacuum dried at a temperature of 150 ° C for 10 hours, and at a spinning temperature of 290 ° C, a spinning speed of 1000 m / min, and a nozzle diameter of 0.23 μm to 12 H (hole), the line at the time of 1 kg spinning was evaluated on the following basis. Breaking frequency. The one who did not break at one time was evaluated as ○, the wire break was confirmed, but the range of operability was evaluated as Δ, and the occurrence of wire breakage was evaluated as ×. ○ and △ are regarded as qualified.

D. Stretchability:

The wire breakage frequency at which the undrawn yarn obtained by spinning was stretched under the conditions of a stretching temperature of 80 ° C and a draw ratio of 2.7 times was evaluated on the following basis. The one who did not break at one time was evaluated as ○, the wire break was confirmed, but the range of operability was evaluated as Δ, and the occurrence of wire breakage was evaluated as ×. ○ and △ are regarded as qualified.

E. melting peak

After being heated to 300 ° C at a temperature increase rate of 16 ° C / min by DSC (differential scanning calorimeter), the temperature was set to a constant temperature of 5 minutes, and then quenched, and then heated up to 300 ° C at a temperature increase rate of 16 ° C / min. The endothermic peak found was used as the melting peak.

(Example 1)

429 g of dimethyl terephthalate and 274 g of ethylene glycol are added to the transesterification reactor of the reaction apparatus in which the transesterification reaction apparatus and the polycondensation reaction apparatus are connected to a transfer tube having a 400-mesh filter. 0.1 g of manganese acetate as a transesterification catalyst was subjected to a transesterification reaction while distilling off methanol at a temperature of 140 to 240 ° C, and then 0.15 g of trimethyl phosphate was added thereto to synthesize BHT. Then, when BHT is transferred from the transesterification reactor to the polycondensation reaction apparatus through a transfer tube, 75 g of polyethylene glycol having a molecular weight of 8300 (PEG6000 manufactured by Sanyo Chemical Industries Co., Ltd.) heated to a temperature of 70 ° C is injected. Stirring was started at the same time as the end of the transfer through the transfer tube in front of the filter. Next, 0.1 g of Irganox 1010 (manufactured by BASF Corporation) as an antioxidant, 0.1 g of antimony as an antifoaming agent, and 0.15 g of antimony trioxide as a polymerization catalyst were placed in a polycondensation reaction apparatus at a reduction of 100 Pa. The polymerization was carried out for 3 hours under the conditions of a temperature of 290 ° C under pressure. After that, the resulting copolymerized polyester strands It was extruded in cold water and immediately cut to obtain a polyester chip.

The proportion of the polyethylene glycol copolymerized in the copolymer obtained in this manner was 15% by weight. Further, the obtained copolymerized polyester had a ΔMR of 3.2% and a glass transition temperature (Tg) of -59 ° C and 90 ° C. The Tg on the low temperature side was calculated as the Tg of the amorphous structure of polyethylene glycol, and the ratio of polyethylene glycol was calculated. The ratio of polyethylene glycol was 89%.

Next, the obtained copolymerized polyester chips were vacuum-dried at a temperature of 150 ° C for 10 hours at a spinning temperature of 290 ° C, an extrusion amount of 32 g / min, a spinning speed of 1000 m / min, and a nozzle diameter of 0.23 μm - 24H (hole). The conditions are melt-spun. The spinnability was good and no line breakage was observed. Subsequently, the stretching was carried out under the conditions of a stretching temperature of 80 ° C and a stretching ratio of 3.3 times. At the time of stretching, no wire breakage or entanglement of the monofilament occurred, and the stretchability was also good.

The fiber composed of the obtained copolymerized polyester had a total fineness of 97 dtex (monofilament fineness: 4 dtex) and ΔMR of 4.0%, and was a fiber excellent in hygroscopicity.

(Examples 2 to 4, Comparative Examples 1 to 2)

The same procedure as in Example 1 was carried out except that the copolymerization ratio of PEG was changed to the values shown in Table 1. The results are shown in Table 1.

As in Examples 2 to 4, the copolymerization ratio of PEG is within the scope of the present invention, and a polyester fiber having high hygroscopicity can be obtained. However, as in Comparative Examples 1 to 2, the copolymerization ratio of PEG was outside the range of the present invention, and the moisture absorption property was low or line breakage occurred at the time of spinning or stretching, and the desired polyester fiber could not be obtained.

(Examples 5 to 6, Comparative Examples 3 to 4)

Except that the molecular weight of PEG was changed to the value shown in Table 1, it was carried out in the same manner as in Example 1. The results are shown in Table 2.

(Comparative Example 5)

The same procedure as in Example 1 was carried out except that the polyethylene glycol was not injected from the transfer tube and the powder was maintained in the polycondensation reaction apparatus. The results are shown in Table 2.

As in Example 6, when the molecular weight of PEG was 20,000, a slight wire break was confirmed in the stretchability, but the workability was not problematic. However, as in Comparative Example 4, when the molecular weight of PEG was 100,000, fiber fibrillation, spinnability and stretchability were deteriorated. This is because the molecular weight of PEG is as large as 100,000, and PEG does not undergo copolymerization but becomes a state of being blended.

As in Example 5, when the molecular weight of PEG was 10,000, there was no problem in spinnability and stretchability.

Further, as in Comparative Example 3, when the molecular weight of PEG was 3,200, the wire was broken, the spinnability was poor, and the stretchability was also inferior.

Further, as in Comparative Example 5, in the case where PEG was added in the form of powder, the glass transition temperature was -67 ° C, mainly including an amorphous structure in which polyethylene glycol coexisted with polyethylene glycol and polyethylene terephthalate. The PEG ratio is 100%. That is, it is not an amorphous structure in which polyethylene glycol and polyethylene terephthalate coexist, but is an amorphous structure of polyethylene glycol alone. Further, the obtained polymer was poor in spinnability and could not obtain fibers.

Claims (5)

A copolymerized polyester characterized in that 10 to 25 wt% of a polyethylene glycol copolymerized in a number average molecular weight of 8,000 to 20,000 is a copolymerized polyester having a main repeating unit of ethylene terephthalate, having a main inclusion The polyethylene glycol coexists with the amorphous structure of polyethylene glycol and polyethylene terephthalate. The copolymerized polyester of claim 1, wherein the ratio of the polyethylene glycol which mainly comprises polyethylene glycol and the amorphous structure of polyethylene glycol and polyethylene terephthalate is from 70 to 99% by weight. The copolymerized polyester according to claim 1 or 2, which is heated to a temperature of 300 ° C at a temperature increase rate of 16 ° C / min by DSC (differential scanning calorimeter), is set to a constant temperature of 5 minutes, and then quenched, and then again When the temperature rise rate was raised to 300 ° C at 16 ° C /min, the melting peak observed in the range of 200 ° C or more was in the range of 251 to 260 ° C. The copolymerized polyester according to any one of claims 1 to 3, wherein the moisture absorption parameter ΔMR is from 2 to 10%. A polyester fiber composed of the copolymerized polyester according to any one of claims 1 to 4.