JPH0258366B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to easily dyeable polyester fibers, and more particularly, the present invention relates to easily dyeable polyester fibers, which are dyed deep and vividly with normal pressure boiling non-carriers against cationic dyes and disperse dyes, have good light fastness of dyed products, and can be dyed with irregular cross-section yarns. This invention relates to easily dyeable polyester fibers that do not cause cracks even when the fibers are dyed. It has long been known that polyester fibers containing 5-metal sulfoisophthalic acid are dyeable with basic dyes and are suitable for use in clothing, carpets, etc. that require a high level of dyeability. There is. (Special Publication No. 10497, etc.). However, this type of basic dye dyeable polyester fiber, for example, 5-
Unless the content of metal sulfoisophthalic acid is 5 mol % or more of the dicarboxylic acid component, it will not be possible to dye the product in a sufficiently deep color by normal pressure (boil) dyeing at 100°C. Therefore, a large amount of 5-metal sulfoisophthalic acid must be used, but as the content of special acidic components that have an affinity with basic dyes increases, the operability in the polymerization and silk-spinning process becomes significantly lower. The production cost of the polymer increases. Furthermore, there were various practical problems such as poor hydrolysis resistance and mechanical properties of this product. Therefore, when obtaining deep-colored and clearly dyed fibers, a copolymerized polyester containing a relatively small amount of acidic group-containing components (5-metal sulfoisophthalic acid, etc.) is obtained, then melt-spun, stretched, and then subjected to high temperature and high pressure. Dyeing was carried out under normal pressure boiling conditions using a carrier. However, since the dyeing conditions under high temperature and high pressure are harsh for this type of polyester fiber, it is impossible to avoid deterioration of the mechanical properties of the fiber, and there is a problem that the dyeing cost is high. In particular, when dyeing a mixture of hair with wool or the like, the dyeing method described above cannot be used because the hair will be significantly damaged if dyed at a temperature of 100° C. or higher. On the other hand, in order to dye at temperatures below 100°C, a carrier must be used, which inevitably increases costs associated with waste liquid treatment. In addition, for carpets and clothing applications that require particularly high bulk, high bulk is imparted by making the cross-sectional shape of the fibers irregular (including trilobal, hollow, etc.). In polyester fibers containing acidic group components such as 5-metal sulfoisophthalic acid, many cracks occur in the fibers during the drawing process, crimping process, dyeing process, etc., and these cracks become a trigger for spinning. It becomes pulverized during the process and causes fluffing and yarn breakage during stretching and spinning. This tendency is particularly noticeable in the case of fibers with irregular cross sections, so the degree of irregularity cannot be increased. Although the cause of this cracking has not yet been elucidated, it is thought to be unique to this type of polyester fiber, and it has been confirmed that it becomes more pronounced the longer the standing time after spinning until it is subjected to stretching. A direct spinning/drawing method has been proposed as a means to solve this problem, but although the cracks are alleviated, the operability is significantly lowered, so it is not practical. In addition, various methods have been proposed to improve the dyeability of polyester fibers dyeable with basic dyes.
For example, so-called chemical modification methods, such as a method in which a modifier mainly containing a metal sulfonate group is added during or after polymerization of polyester, a method in which bifunctional carboxylic acid is further copolymerized to disturb molecular orientation, or Examples include a combined chemical and physical modification method in which highly oriented polyester containing metal sulfonate groups is spun and further stretched at a specific stretching temperature and stretching ratio, and furthermore, a material modification method. However, with chemical modification methods, although the effect of improving dyeability is recognized to a certain extent, it causes a decrease in light resistance, a decrease in melting point, a decrease in strength and elongation physical properties, and it is difficult to control the content because the modifier is easily distilled out. and
Furthermore, the problem of increased costs due to the addition of modifiers also arises. In addition, a combination of chemical and physical modification improves the dyeing rate and brightness slightly, but it is difficult to obtain a sufficiently deep color, and the undrawn yarn obtained by high-speed spinning must be drawn under special conditions, which increases production costs. is expensive (JP-A No. 50-89632, etc.). Furthermore, as a physical modification method,
There have been many proposals, such as JP-A-55-40876, which improves the direct spinning and drawing method based on JP-B-52-8418, but all of them are lacking in terms of light resistance and deep color clarity. I have to say that's enough. The present inventors focused on the above-mentioned matters, and in particular, suppressed the problems in chemical modification methods, namely, the decrease in light fastness and melting point, while achieving a deeper and more vivid dyeing state by boiling non-carrier dyeing. We are conducting research with the aim of obtaining a hydrophilic group-containing modifier with excellent light resistance, and have already filed a patent application for this method (Japanese Patent Application No. 55-138574 and its application). (Japanese Patent Application No. 128090/1983, which is a divisional application from 1983). The inventors of the present invention continued their research and achieved even better light fastness and deep color by using voile non-carrier dyeing.
In order to provide easy-to-dye polyester fibers that provide vividness, we have been conducting research in particular on the physical properties and internal structure of polyester fibers. The present invention was completed as a result of such research, and consists of (1) a copolymer polyester of a dicarboxylic acid component and a glycol component, in which 80 mol% or more of the dicarboxylic acid component is terephthalic acid; or its ester-forming derivative, in which 80 mol% or more of the glycol component is one or more glycols selected from ethylene glycol, tetramethylene glycol, and 1,4-cyclohexanediol, and 1% or more of the glycol component is one or more glycols selected from ethylene glycol, tetramethylene glycol, and 1,4-cyclohexanediol, and ~
It is composed of a copolymerized polyester in which 10% by weight is a glycol represented by the following general formula [], and the gist is that the temperature (Tα) at which the loss tangent (Tanδ) in viscoelasticity measurement is maximum is 90 to 110°C. It is something. HO(−C _k H _2k O) _−n R−O(−C _l H _2l O)− _o H
...[] (In the formula, R is a divalent aliphatic hydrocarbon group having 4 to 20 carbon atoms, k and l are the same or different integers of 2 to 4, m and n are the same or different integers, and 1≦ (m
+n)≦10. ) The easily dyeable polyester fiber according to the present invention has the above-mentioned structural characteristics regarding the copolymer composition, and also has a temperature (Tα) at which the loss tangent (Tanδ) in viscoelasticity measurement reaches a maximum value of 90 to 110. It is also an important component that it is defined as ℃. It has been conventionally believed that the temperature (Tα) at which Tanδ is at its maximum is the measure of the ease with which micro-Brownian motion of molecular motion in the amorphous portion occurs when looking at the fiber from a microstructural perspective. The higher the value, the larger the micro-Brownian momentum. Therefore, the lower Tα and the higher Tanδ, the greater the diffusion of dye molecules,
Improves stainability. In this regard, the Tα of the polyester fiber of the present invention is 90 to 110°C, which is extremely low compared to known fibers, so the dye exhaustion is good, and even with a boiled non-carrier, dyed products with sufficiently deep and vivid colors can be obtained. can be obtained. However, if the temperature is lower than 90°C, a problem arises in that the hydrolysis resistance decreases, as shown in Comparative Example 2 below. On the other hand, Tα
If the temperature is higher than 110°C, it is not possible to obtain dyed products with sufficiently deep colors using boiled non-carriers. The preferable Tanδ at the preferable Tα point of the fiber of the present invention is
It is 0.2 or more. The polyester fiber according to the present invention is one in which the relationship between the crystal size ACS in the 100 planes of the equatorial diffraction curve determined by wide-angle X-ray diffraction method and the crystal orientation angle (θc) in the 100 planes satisfies the following formula [] It is desired that θc≦{9.0−(0.14ACS)} ...[] If the requirements of the above formula [] are not satisfied, please refer to JIS・
The temporary mechanical property measure evaluated by the product of the tensile strength (DT) determined by L-1074 and the 1/2 power of the elongation (DE) becomes lower. The reason for this has not yet been clarified despite the efforts of the present inventors. The above-mentioned DE is preferably less than 80%, and if it exceeds this value, it is not preferable, especially in the case of top dyeing, since color spots called "eye peeling" tend to appear on the fabric. Although the reason for this is still unknown, there is a tendency for the higher the DE, the higher the θc. The preferred θc value in the present invention is 6.0 degrees or less, more preferably 5.0 degrees or less. Next, a preferable polyester composition constituting the fiber according to the present invention will be explained, but it is of course possible to blend it with other polyesters and spin the fiber at or before the spinning stage. In the preferred copolyester constituting the fiber of the present invention, 80 mol% or more of the dicarboxylic acid component is terephthalic acid or its ester-forming derivative, and further 0.5 to 5 mol%, preferably 0.5 to 3.5 mol% - It consists of metal sulfoisophthalic acid or its ester-forming derivative. If the content of 5-metal sulfoisophthalic acid is less than 0.5 mol%, the number of dyeing seats for the cationic dye will be insufficient and the amount to retain the cationic dye that has penetrated into the fiber will be insufficient, resulting in poor dyeing properties and color development of the dyed product. becomes scarce. On the other hand, if it exceeds 5 mol %, the mechanical properties of the fiber itself will be significantly reduced, which will be a problem in practical use, and the operability during spinning will also be significantly reduced, making it more expensive. In addition, 5-metal sulfoisophthalic acid further reduces light resistance and hydrolysis resistance, as well as lowering the melting point, so it is best to reduce it as much as possible, especially to keep it below 3 mol% to ensure high mechanical properties. is desired, but in normal use it is 5 mol%.
If it is below, there is no practical problem. The metal of 5-metal sulfoisophthalic acid may be any metal as long as it can form a salt with a sulfonic group, such as alkali metal calcium such as sodium, potassium, lithium, alkaline earth metal lanthanum such as barium, etc. The most common is sodium. Further, as the ester-forming derivative of the dicarboxylic acid, esters with lower alcohols such as methanol and ethanol are generally used, but esters with glycols such as ethylene glycol can also be used. In addition, as other dicarboxylic acid components, aromatic dicarboxylic acids such as isophthalic acid and naphthalene dicarboxylic acid, or ester-forming derivatives thereof, glutaric acid, adipic acid, azelaic acid, sebacic acid, etc. may be used as long as the quality of the copolymerized polyester is not deteriorated. aliphatic dicarboxylic acid or its ester-forming derivative, P-(2-hydroxyethoxy)
Oxydicarboxylic acids such as benzoic acid or ester-forming derivatives thereof can also be used in combination. Next, as a glycol component, it is preferable that 80 mol% or more of it is one or more glycols selected from ethylene glycol, tetramethylene glycol, and 1,4-cyclohexanedimethanol, and among them, ethylene glycol is most suitable. It is. In addition, as another glycol component, a polyester containing 1 to 10% by weight, preferably 1.5 to 6% by weight of a glycol represented by the general formula [] shown below as a copolymerization component represented by the formula [] below is used. Awarded. As will be described later, the glycol of the general formula [] has the function of increasing the affinity with water, which is a special dye transport medium, increasing the diffusion rate of the dye, and improving the dyeability. Moreover, it has the effect of lowering (Tα) of the resulting copolymerized polyester and increasing (Tan δ) at the (Tα) point. Although the reason for this is not necessarily clear, it is thought that by employing a special spinning method as described below, the orientation of the crystal parts is hindered by the plasticizing effect. In addition, the glycol represented by the general formula [] is
Unlike other high-molecular-weight polyethylene glycols that have a plasticizing effect, it does not damage the light resistance of dyed products, and its melting point lowering effect is much smaller than that of low-molecular-weight glycols such as neopentyl glycol and diethylene glycol. There are also advantages. If the content of the glycol represented by the general formula [] is less than 1% by weight, dyeability cannot be sufficiently improved, while if it exceeds 10% by weight, the light fastness of the dyed product will be significantly impaired. Particularly preferable content is 1.5~
6% by weight, and if a higher degree of light resistance is required, it is preferably used in combination with the aforementioned 5-metal sulfoisophthalic acid. HO(−C _k H _2k O) _−n R−O(−C _l H _2l O)− _o OH
...[] [(-C _k H _2k O) _-n R-O(-C _l H _2l O) _-o ]
...[] In the above general formula [] and general formula [], R
is a divalent aliphatic hydrocarbon group having 4 to 20 carbon atoms, such as a linear aliphatic hydrocarbon group such as ( _-CH2 ) _-6 , ( _-CH2 ) _-10 , _-CH2- CH( _CH3 ) _−CH2− ,
CH ₂ −C(CH ₃ ) ₂ −CH ₂ −, −CH(CH ₃ )CH ₂ −
an aliphatic hydrocarbon group having a side chain such as CH ₂ −,

【formula】

【formula】

【formula】

Examples include hydrocarbon groups having an aliphatic cyclic group such as the formula: Among them, an aliphatic hydrocarbon group having a side chain, particularly a 2,2-dimethylpropylene group, is most suitable. In addition, the glycol represented by the general formula [] can be prepared by HO-R-
It can be synthesized by adding ethylene oxide to the glycol represented by OH. The average value of (m+n) in the general formula [] is 1 to 10,
More preferably, it is 2 to 8, and even more preferably 3 to 6. If (m+n) = 0, it is undesirable because it tends to distill off during the polymerization reaction and the melting point of the copolyester becomes low. On the other hand, if it exceeds 10, the light resistance of the dyed fibers decreases. Sexuality becomes poor. However, as long as the effect of the present invention is not impaired, a small amount of glycol represented by HO-R-OH or a glycol in which (m+n) in the general formula [] exceeds 10 may be included, and furthermore, the above-mentioned glycols may be included. HO-R
In addition to the glycol represented by -OH, small amounts of diethylene glycol, triethylene glycol, propylene glycol, 1,4-bis(β-hydroxyethoxy)benzene, bisphenol A, bisethoxylated 2,2-bis(2,5-dimethyl −
4-hydroxyphenyl)propane, diphenylsilanol, etc. may be included. Further, a branched component such as pentaerythritol or pyromellitic acid may be copolymerized within a range that does not impede the moldability of the polyester. The method for producing a copolymerized polyester using each of the above raw material components is not particularly restricted and may be carried out according to a normal polyester production method, but as a general method, a dicarboxylic acid or its ester-forming derivative and a A method of subjecting metal sulfoisophthalic acid or its ester-forming derivative to a transesterification reaction with a glycol component and then subjecting it to a polycondensation reaction,
Examples include a method in which a dicarboxylic acid component and a glycol component are subjected to an esterification reaction and then subjected to polycondensation. When obtaining a polyester through an esterification reaction, it is preferable to add the glycol of the general formula [] from just before the end of the esterification reaction to the start of the polycondensation reaction to suppress decomposition of ether bonds. Metal compounds such as sodium, magnesium, calcium, manganese, zinc, titanium, antimony, germanium, and tungsten are generally used as catalysts in the transesterification, esterification, and polycondensation reactions. The easily dyeable polyester fiber of the present invention can be produced by a method in which the copolymerized polyester is made into a highly oriented undrawn yarn by a high-speed spinning method, then stretched at high temperature and low tension, and if necessary heat-treated by a conventional method, or 55−
12832 and 56-316 (the yarn melt-spun from the spinneret is once cooled and solidified, and then in a heating zone provided before reaching the yarn take-up device). The yarn can be obtained by a method such as passing the fiber through the fiber and drawing it under a temperature gradient by the frictional force with the air to form a drawn yarn all at once. In this case, it is preferable to use an asymmetrical cooling method in combination because it provides a three-dimensional crimp function and the crimp imparting step can be omitted. By the way, in order to achieve the purpose of the present invention, the take-up speed in the above special direct spinning and drawing process must be
It should be at least 3000 m/min, preferably between 4000 and 6000 m/min. However, if the take-up speed is less than 3000 m/min, the mechanical properties of the obtained fibers will be poor and cracks will occur during the heat treatment process. On the other hand, if the speed exceeds 6000 m/min, the dyeing properties will deteriorate, which is not preferable. By the method described above, it is possible to obtain easily dyeable polyester fibers that not only satisfy the requirements of 90°C≦Tα≦110°C but also achieve the following values: θc≦9.0−0.4ACS DT≧1g/dDE≦60. The fiber of the present invention obtained in this way is
It absorbs disperse dyes and basic dyes well even under normal pressure boil non-carrier dyeing conditions, exhibits extremely excellent dyeability and clear dyeability, and has good light fastness of dyed products and is made into yarn with irregular cross sections. It can be said to be an ideal fiber as it does not cause cracks even when The denier of the single yarn of the fiber of the present invention is not particularly limited, but for staple use, it is generally 0.5 to 6 denier for spun yarn types, and 3 to 20 denier for carpet use. Similarly, in filament applications, the optimum denier and number of filaments can be freely selected depending on the application. Next, examples of the present invention will be shown. The various measured values specified in the present invention were measured by the following methods. Quantitative analysis of the glycol component in the polyester was carried out by determining the amount of H atoms by NMR, and the melting point of the polyester was measured by DSC using a sample amount of 10 mg and a heating rate of 20° C./min in a nitrogen atmosphere. Further, 5-metal sulfoisophthalic acid in the polyester was determined by a method of quantifying S atoms from relative values with a standard substance using fluorescent X-rays. The dyeing rate with disperse dye is Dispersol Earth Scarlet B (manufactured by ICI, disperse dye)
4.0% owf, Disper TL (manufactured by Meisei Kagaku Kogyo Co., Ltd.,
Dispersant) 1g/, bath ratio 1:100, the sample was dyed for 90 minutes at normal pressure boiling temperature (98℃), and the dyeing rate with basic dye was Cevron Blue B (manufactured by DuPont,
Basic dye) 10% owf, 0.2 g each of acetic acid and sodium acetate, bath ratio 1:100, dye the sample for 90 minutes at normal pressure and boiling temperature, measure the staining solution absorbance before and after dyeing, and calculate using the following formula. did. Dyeing rate (%) = 100 (X-Y)/X A sample dyed at 1g/1:100 for 90 minutes at normal pressure and boiling temperature (98°C) was washed with water and dried, and then evaluated in terms of fluorescence reflectance (%). Light resistance is determined by Resolin Red FB (manufactured by Bayer).
Dispersible dye) 0.2% owf, Disper TL 1g/,
The sample was dyed for 60 minutes at a bath ratio of 1:100 at normal pressure and boiling temperature, and after reduction cleaning according to the usual method, JIS-L-
Dyeing with a fade-o-meter according to 0342
The color was photobleached by irradiation for 40 hours and expressed as fastness (grade) based on the blue scale standard. Hydrolysis resistance was determined by immersing sample fibers in pure water (PH5.7) at a bath ratio of 1:100 and treating them at normal pressure and boiling temperature for 4 hours. d) was measured and expressed as a retention rate with respect to the breaking strength before treatment. Temperature dependence of loss tangent (Tanδ) Using Rheovibron manufactured by Toyo Sokki Co., Ltd.
cm, heating rate 2 from measurement temperature 25℃ to 200℃
Measured under the conditions of ℃/min and measurement frequency 110Hz, tanδ
Find the temperature (Tα) at which is the maximum. Single yarn denier Measured according to JIS-L1073 (1965). Woolen yarn denier Measured according to JIS-L1095 (1979). Tensile strength (DT) and elongation (DE) Measured according to JIS-L1074 (1977). Crystal size ACS (100) of equatorial diffraction curve in wide-angle X-ray diffraction diagram
Calculated using Sherrer's formula from the half-width of the surface diffraction intensity [For details, see Maruzen Co., Ltd. [X-ray Crystallography] (Supervised by Isamu Nita) Volume 1, page 140] Sherrer's formula is expressed by the following formula. . [However, in the above formula, λ is the wavelength of the X-ray (Å), B is the half-width (radq), α is the correction angle (6.98×10 ^-4 rad), and θ
is the diffraction angle (degrees)] The X-rays used in the examples of the present invention are
45KV, tube current 70mA, copper anticathode, Ni filter, wavelength 1.54Å, the diffractometer was a SG-7 goniometer manufactured by Rigaku Denki Co., Ltd., and the X-ray generator was a rotorflex.
RU-3H type was used. Crystal orientation angle θc is defined as the half width (Bm) of the (100) plane diffraction intensity of the diffraction curve along the Debye ring in a wide-angle X-ray diffraction diagram (see page 600 of the above-mentioned “X-ray Crystallography”). The X-ray, diffractometer, and X-ray generator used for the measurement are the same as those used for the measurement of crystal size ACS. Example 1 and Comparative Example 1 100 parts of dimethyl terephthalate (DMT) (parts by weight: the same below), a specified amount of 5-sodium sulfoisophthalic acid dimethyl ester (DSN), 700 parts of ethylene glycol (EG), and R in the general formula [] is a 2,2-dimethylpropylene group and the value of (m+n) is changed or the molecular weight is
A predetermined amount of polyester glycol (PEG) of 2000 was placed in a transesterification reactor, 0.38 parts of zinc acetate dihydrate, 0.50 parts of sodium acetate, and 0.33 parts of antimony trioxide were added thereto, and the mixture was heated at 130 °C to 150 to 220 °C.
The transesterification reaction was carried out while raising the temperature over a period of minutes and distilling off methanol as a by-product. This reaction powder is cooled by blowing cold air from one side at a speed of 2.0 m/sec, then passed through a 120 cm long heating heater installed at a position 3 m below the spinneret, and further
7200 denier/2400 multifilaments were produced by drawing at a speed of 4000 m/min. Cut this multifilament yarn into a length of 70 mm to make a staple, and dry heat the staple at 145℃.
A three-dimensional three-dimensional crimped staple was produced by relaxing heat treatment for 5 minutes, and the staple cotton was subjected to X-ray diffraction analysis.
The temperature dependence of ACS, θc, and loss tangent (Tanδ) for 100 planes was measured. The obtained staples were made into slivers using a roller card in a normal roughing process, and while the slivers were aligned and drafted, 17 parts of an EG solution containing 22% titanium dioxide was added to the threads, and then diethyl-2-carbohydrate was added to the threads. 0.8 parts of ethoxyethylphosphonate was added and held for 10 minutes. The obtained product was transferred to a polycondensation vessel at 210 °C and heated to 80 °C.
The internal temperature was raised to 210 to 275°C over several minutes while the pressure on the yarn was gradually reduced, and a condensation reaction was then carried out at 275°C and 0.1 mm of Hg for 40 minutes to obtain a copolymerized polyester of a predetermined composition. This copolymerized polyester is spun at a
At 280℃, C-shaped slit-shaped spinning hole (outermost diameter 1.0
The yarn is spun at a discharge rate of 3,200 g/min from a spinneret with 2,000 pieces (mm, slit width 0.15 mm) perforated, and the roving is spun into roving using a room temperature cooling air flow directly below the spinning nozzle. After making 16 count yarn, date 400
After knitting to an interlock of g/cm ² and scouring, the dyeing rate, sharpness, light resistance, and hydrolysis resistance were measured, and the occurrence of cracks in the fibers was observed. The results are summarized in Table 1 together with the copolyester composition and the melting point of the copolyester. Comparative Example 2 Using a copolymerized polyester prepared in the same manner as in Example 1 and Comparative Example 1, the spinning temperature was 280°C, and the yarn take-up speed was 1300 m/min, 2500 m/min, or 4000 m/min.
minute, cooling air speed 0.3m/min, heating heater temperature
22,000 denier/2,400 undrawn yarns were obtained in the same manner as above except that the temperature was changed to 20°C. This undrawn yarn is drawn by a factor of 2.6 using a known drawing device equipped with a steam jet slit and a 160°C hot plate in series, and then the two multifilaments are pulled together and mechanically crimped using a push-in crimper. and 70
After cutting into staples having a length of mm, mechanically crimped staple cotton was manufactured by subjecting it to relaxation heat treatment at 145° C. for 5 minutes. 100 by X-ray diffraction method of the obtained staple cotton
The temperature dependence of ACS, θc, and loss tangent (Tanδ) of the surface was investigated. This staple cotton is made into a 16 count wool yarn in the same manner as above, then knitted into an interlock yarn with a basis weight of 400 g/cm ² , and after scouring, the dyeing rate, brightness, light fastness, and hydrolysis resistance are measured. At the same time, the occurrence of cracks in the fibers was observed. The results are shown in Table 1 along with the copolyester composition and the melting point of the copolyester. Incidentally, in the coarse hair process in this example, pulverization occurred and the operability deteriorated significantly. Comparative Example 3 Polyethylene terephthalate with an intrinsic viscosity of 0.63 was melt-spun through a melt spinneret, cooled to a temperature of 80°C or less by blowing cooling air directly below the spinneret, and then placed at a position 3 m below the spinneret. The yarn was stretched by passing through a heater having a length of 120 cm and a temperature of 302°C, and then passed through a first take-up roller at a speed of 6100 m/min, and the yarn was wound. Table 1 shows the physical properties, dyeability, light resistance, etc. of the obtained filament.

【table】

[Table] As is clear from Table 1, the easily dyeable polyester fibers that meet the requirements of the present invention have no practical problems in terms of mechanical properties, and have excellent deep dyeability, sharpness, and light resistance. In particular, even compositions with a low content of 5-metal sulfoisophthalic acid exhibit excellent properties. On the other hand, comparative examples that do not meet the requirements of the present invention fail to satisfy any of the characteristics.

Claims (1)

[Scope of Claims] 1. A copolymer polyester of a dicarboxylic acid component and a glycol component, in which 80 mol% or more of the dicarboxylic acid component is terephthalic acid or its ester-forming derivative, and 80 mol% of the dicarboxylic acid component is
mol% or more of one or more glycols selected from ethylene glycol, tetramethylene glycol, and 1,4-cyclohexanediol, and 1 to 10% by weight of the resulting polyester is a glycol represented by the following general formula [] The temperature (Tα) at which the loss tangent (Tanδ) is maximum in viscoelasticity measurement is 90.
Easily dyeable polyester fiber characterized by a temperature of ~110℃. HO(−C _k H _2k O) _−n R−O(−C _l H _2l O)− _o H
...[] (In the formula, R is a divalent aliphatic hydrocarbon group having 4 to 20 carbon atoms, k and l are the same or different integers of 2 to 4,
m and n are the same or different integers, 1≦(m+n)≦
It is 10. ) 2 In claim 1, an easy-to-dye product composed of a copolymerized polyester in which 0.5 to 5.0 mol% of the dicarboxylic acid component is composed of 5-metal sulfoisophthalic acid or its ester-forming derivative. polyester fiber.