JP2009161670A - Cation-dyeable polyester - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a cation-dyeable polyester providing high-tenacity fibers. <P>SOLUTION: The cation-dyeable polyester is a polyester composed of ethylene terephthalate being its main repeating unit, and is a copolyester which contains, in an acid component constituting the polyester, a metal salt (A) of sulfoisophthalic acid and a compound (B) represented by formula (I) in such a state that the following expressions (1) and (2) are simultaneously satisfied. In the formula (I), R represents a hydrogen atom or C1-10 alkyl group and X represents a quaternary phosphonium ion or quaternary ammonium ion. In the expressions (1): 0.3≤A+B≤3.0 and (2): 0.2≤B/(A+B)≤0.7, A and B represent copolymerization amounts (mole%) of the metal salt (A) and the compound (B), respectively. A diethylene glycol content in the copolyester is 2.5 wt.% or less. An intrinsic viscosity of the polyester obtained is in the range of 0.55-1.00 dL/g. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a cationic dyeable polyester that is dyeable to a cationic dye and a fiber comprising the same.

  Polyesters, especially polyethylene terephthalate, polyethylene naphthalate, polytrimethylene terephthalate and polytetramethylene terephthalate are widely used as fibers, films and other molded products because of their excellent mechanical, physical and chemical properties. Yes. In particular, polyethylene terephthalate is used in a very wide range of applications because of its characteristics and price.

  Polyesters typified by polyethylene terephthalate have been variously modified depending on the application, and copolyesters obtained by copolymerizing various components are widely known. Among these, cationic dyeable polyesters obtained by copolymerizing components having cationic dyeability are widely known mainly for clothing applications.

  Polyethylene terephthalate usually used to obtain such a cationic dyeable polyester is usually obtained by directly esterifying terephthalic acid and ethylene glycol, for example, a lower alkyl ester of terephthalic acid such as dimethyl terephthalate and ethylene glycol. Is transesterified, or terephthalic acid and ethylene oxide are reacted to form an ethylene glycol diester of terephthalic acid and / or a low polymer thereof. Next, this reaction product is produced by heating under reduced pressure in the presence of a polycondensation catalyst to carry out a polycondensation reaction until a predetermined degree of polymerization is obtained. At any stage of this production process, sulfone, which is a copolymerization component, is produced. A method is adopted in which a cationic dyeable monomer is obtained by copolymerizing 2 to 3 mol% of a cationic dyeable monomer typified by a metal salt of isophthalic acid and dyed at a high temperature and high pressure (for example, (See Patent Document 1.)

  However, since typical cationic dyeable monomers such as 5-sodium sulfoisophthalic acid and derivatives thereof, which are typical cationic dyeable monomers, are ionic components, ionic bonds are formed in the polyester polymerization stage. Since the intermolecular force works and the melt viscosity increases, it is difficult to produce a high molecular weight cationic dyeable polyester, and the strength of the fiber obtained by melt spinning is low. .

  In order to solve such a problem, a technique of copolymerizing a cationic dyeable monomer having a small ion binding intermolecular force has been disclosed (for example, see Patent Document 2 and Patent Document 3). Examples of cationic dyeable monomers having a small ion binding intermolecular force include 5-sulfoisophthalic acid tetrabutylphosphonate. These cationic dyeable monomer copolyesters have poor thermal stability and are heavy. It is well known that the quality of polyester depends greatly on the type of catalyst used in the condensation step. Moreover, although the strength of the obtained yarn is improved as compared with the case of using the above-mentioned 5-sodium sulfoisophthalic acid and its derivatives, the 5-sulfoisophthalic acid tetrabutylphosphonate used is very expensive, and as a result There was a problem that the cost of the resulting cationic dyeable polyester increased significantly.

Japanese Patent Publication No.34-10497 JP-A-1-162822 JP 2006-176628 A

  The object of the present invention is to solve the above-mentioned problems, and to provide a cationic dyeable polyester capable of obtaining a highly strong fiber capable of cationic dyeing and a cationic dyeable polyester fiber comprising the same. .

  In view of the above problems, the present inventors have intensively studied, and as a result, have completed the present invention. That is, the present invention is a copolyester in which the main repeating unit is composed of ethylene terephthalate, and is represented by the metal salt of sulfoisophthalic acid (A) and the following formula (I) in the acid component constituting the copolyester. A copolyester containing the compound (B) satisfying the following mathematical expressions (1) and (2) at the same time, the glass transition temperature of the copolyester being in the range of 70 to 85 ° C. A cationic dyeable polyester characterized in that the intrinsic viscosity of the copolymerized polyester is in the range of 0.55 to 1.00 dL / g, whereby the above-mentioned problems can be solved.

［上記式中、Ｒは水素原子又は炭素数１〜１０個のアルキル基を表し、Ｘは４級ホスホニウムイオン又は４級アンモニウムイオンを表す。］
０．３≦Ａ＋Ｂ＜３．０ （１）
０．２≦Ｂ／（Ａ＋Ｂ）≦０．７ （２）
［上記数式中、Ａは共重合ポリエステルを構成する全酸成分を基準とするスルホイソフタル酸の金属塩（Ａ）の共重合量（モル％）、Ｂは共重合ポリエステルを構成する全酸成分を基準とする上記式（Ｉ）で表される化合物（Ｂ）の共重合量（モル％）を表す。］

[In the above formula, R represents a hydrogen atom or an alkyl group having 1 to 10 carbon atoms, and X represents a quaternary phosphonium ion or a quaternary ammonium ion. ]
0.3 ≦ A + B <3.0 (1)
0.2 ≦ B / (A + B) ≦ 0.7 (2)
[In the above formula, A is the copolymerization amount (mol%) of the metal salt of sulfoisophthalic acid (A) based on the total acid component constituting the copolyester, and B is the total acid component constituting the copolyester. This represents the copolymerization amount (mol%) of the compound (B) represented by the above formula (I) as a reference. ]

  ADVANTAGE OF THE INVENTION According to this invention, the polyester fiber which has favorable dyeing | staining property by cationic dyeing and has higher intensity | strength than the conventional cationic dyeable polyester can be provided, hold | maintaining the outstanding characteristic of polyester.

  Hereinafter, the present invention will be described in detail. The copolymerized polyester used in the present invention is a copolymerized polyester mainly composed of ethylene terephthalate obtained by polycondensation reaction of terephthalic acid or an ester-forming derivative thereof and an ethylene glycol component. A copolyester containing a metal salt of sulfoisophthalic acid (A) as a component and a compound (B) represented by the following formula (I) in a state satisfying the following mathematical formulas (1) and (2) simultaneously: The polyester is characterized in that the glass transition temperature of the copolyester is in the range of 70 to 85 ° C., and the intrinsic viscosity of the copolyester obtained is in the range of 0.55 to 1.00 dL / g.

［上記式中、Ｒは水素原子又は炭素数１〜１０個のアルキル基を表し、Ｘは４級ホスホニウム塩又は４級アンモニウム塩を表す。］
０．３≦Ａ＋Ｂ＜３．０ （１）
０．２≦Ｂ／（Ａ＋Ｂ）≦０．７ （２）
［上記数式中、Ａは共重合ポリエステルを構成する全酸成分を基準とするスルホイソフタル酸の金属塩（Ａ）の共重合量（モル％）、Ｂは共重合ポリエステルを構成する全酸成分を基準とする上記式（Ｉ）で表される化合物（Ｂ）の共重合量（モル％）を表す。］

[In the above formula, R represents a hydrogen atom or an alkyl group having 1 to 10 carbon atoms, and X represents a quaternary phosphonium salt or a quaternary ammonium salt. ]
0.3 ≦ A + B <3.0 (1)
0.2 ≦ B / (A + B) ≦ 0.7 (2)
[In the above formula, A is the copolymerization amount (mol%) of the metal salt of sulfoisophthalic acid (A) based on the total acid component constituting the copolyester, and B is the total acid component constituting the copolyester. This represents the copolymerization amount (mol%) of the compound (B) represented by the above formula (I) as a reference. ]

  Here, the ester-forming derivative of terephthalic acid is dimethyl ester, diethyl ester, dipropyl ester, dibutyl ester, dihexyl ester, dioctyl ester, didecyl ester, or diphenyl ester or terephthalic acid dichloride, terephthalic acid diterephthalic acid. Among them, dimethyl terephthalate is preferable.

(About copolymer polyester)
The copolymer polyester in the present invention is a polyester having ethylene terephthalate as a main repeating unit, and the main repeating unit indicates that 80 mol% or more of all repeating units constituting the copolymer polyester is an ethylene terephthalate unit. . Other components may be copolymerized within the other 20 mol% or less range. Preferably 90 mol% or more is an ethylene terephthalate unit. Other copolymer components include diphthalic acid components such as isophthalic acid, 2,6-naphthalenedicarboxylic acid, 2,7-naphthalenedicarboxylic acid, 4,4′-diphenyldicarboxylic acid, 4,4′-diphenylmethanedicarboxylic acid, diphenyl Examples thereof include ketone dicarboxylic acid, 4,4′-diphenylsulfone dicarboxylic acid, succinic acid, adipic acid, and azelaic acid, and 1,2-propylene glycol, trimethylene glycol, tetramethylene glycol, heptamethylene glycol, Hexamethylene glycol, diethylene glycol, dipropylene glycol, bis (trimethylene glycol), bis (tetramethylene glycol), triethylene glycol, 1,4-dihydroxycyclohexane, 1,4-cyclohexa Can dimethanol mentioned, it may be copolymerized as a repeating unit derived component by reacting these one or more dicarboxylic acids and one or more glycol components.

(About metal salt of sulfoisophthalic acid (A))
Examples of the metal salt (A) of sulfoisophthalic acid used in the present invention include alkali metal salts (lithium salt, sodium salt, potassium salt, rubidium salt, cesium salt) of 5-sulfoisophthalic acid. If necessary, alkaline earth salts such as magnesium salts and calcium salts of these compounds may be used in combination. These ester-forming derivatives are also preferably exemplified. Examples of the ester-forming derivative include dimethyl ester, diethyl ester, dipropyl ester, dibutyl ester, dihexyl ester, dioctyl ester, didecyl ester, diphenyl ester, and dihalogenated metal salt of 5-sulfoisophthalic acid. Of these, dimethyl ester is preferred. Among these compounds, an alkali metal salt of 5-sulfoisophthalic acid is preferably exemplified from the viewpoint of thermal stability, cost, etc., and in particular, 5-sodium sulfoisophthalic acid which is 5-sodium sulfoisophthalic acid or a dimethyl ester thereof. Particularly preferred is dimethyl acid. In the case of a compound satisfying these conditions, it is possible to achieve both sufficient cationic dyeability and sufficient fiber strength when used as a polyester fiber.

(Compound (B))
The compound (B) represented by the above formula (I) is quaternary phosphonium salt or quaternary ammonium salt of 5-sulfoisophthalic acid or a lower alkyl ester thereof. As the quaternary phosphonium salt or quaternary ammonium salt, a quaternary phosphonium salt or a quaternary ammonium salt in which an alkyl group, a benzyl group or a phenyl group is bonded to a phosphorus atom or a nitrogen atom is preferable, and a quaternary phosphonium salt is particularly preferable. preferable. The four substituents may be the same or different. Specific examples of the compound represented by the above formula (I) include 5-sulfoisophthalic acid tetrabutylphosphonium salt, 5-sulfoisophthalic acid ethyltributylphosphonium salt, 5-sulfoisophthalic acid benzyltributylphosphonium salt, and 5-sulfoisophthalic acid. Acid phenyltributylphosphonium salt, 5-sulfoisophthalic acid tetraphenylphosphonium salt, 5-sulfoisophthalic acid butyltriphenylphosphonium salt, 5-sulfoisophthalic acid benzyltriphenylphosphonium salt, 5-sulfoisophthalic acid tetramethylammonium salt, 5- Sulfoisophthalic acid tetraethylammonium salt, 5-sulfoisophthalic acid tetrabutylammonium salt, 5-sulfoisophthalic acid tetraphenylammonium salt, 5-sulfoisophthalic acid benzyl trime Le ammonium salt, 5-sulfoisophthalic acid benzyl trimethyl ammonium salt, or dimethyl esters thereof isophthalic acid derivatives, the diethyl ester, dipropionate pull ester, dibutyl ester, hexyl ester to di, dioctyl ester, didecyl ester is preferably exemplified. Among these isophthalic acid derivatives, 5-sulfoisophthalic acid dimethyltetrabutylphosphonium salt, 5-sulfoisophthalic acid dimethylbenzyltributylphosphonium salt, 5-sulfoisophthalic acid dimethyltetraphenylphosphonium salt, 5-sulfoisophthalic acid dimethyltetramethylammonium salt More preferred examples include salts, dimethyltetraethylammonium salt of 5-sulfoisophthalic acid, dimethyltetrabutylammonium salt of 5-sulfoisophthalic acid, and dimethylbenzyltrimethylammonium salt of 5-sulfoisophthalic acid. In the case of a compound satisfying these conditions, it is possible to achieve both sufficient cationic dyeability and sufficient fiber strength when used as a polyester fiber.

(About Formula (1))
In the present invention, the total of the above-mentioned sulfoisophthalic acid metal salt (A) to be copolymerized with the polyester and the above-mentioned compound (B) is based on the total acid component constituting the copolymerized polyester, and the (A) component and (B ) The sum A + B of the components needs to be in the range of 0.3 mol% or more and less than 3.0 mol%. When the amount is less than 0.3 mol%, the dyeability with respect to the cationic dye becomes insufficient. On the other hand, if it is 3.0 mol% or more, the strength of the resulting polyester yarn is lowered, which is not preferable. Preferably it is 0.5-2.8 mol%, More preferably, it is 1.0-2.7 mol%.

(About Formula (2))
Further, the component ratio of the metal salt (A) of sulfoisophthalic acid and the compound (B) needs to be in the range of 0.2 to 0.7, with B / (A + B) being the value of the above mol%. In the state of 0.2 or less, that is, in a state where the proportion of component A is large, it is difficult to increase the degree of polymerization of the resulting copolyester due to the thickening effect by the metal salt of sulfoisophthalic acid. On the other hand, when the ratio of the compound (B) is 0.7 or more, that is, the polycondensation reaction is slow, and when the ratio of the compound (B) is further increased, it is difficult to increase the degree of polymerization because the thermal decomposition reaction proceeds. Become. Furthermore, when the ratio of the compound (B) increases, the thermal stability of the copolyester deteriorates, and the decrease in the molecular weight due to the thermal decomposition reaction upon remelting at the melt spinning stage increases, so the strength of the resulting polyester yarn decreases. Therefore, it is not preferable. Preferably it is 0.23-0.65, More preferably, it is 0.25-0.60.

  Although cationic dyeability can be imparted by copolymerizing a metal salt of sulfoisophthalic acid (A) with polyester, an increase in the melt viscosity of the copolymerized polyester that is thought to be derived from ionic bonds between the metal sulfonate groups. It was difficult to increase the degree of polymerization of the copolyester due to the viscous effect. Therefore, a copolyester having a sufficiently high degree of polymerization and a high intrinsic viscosity cannot be obtained, and the polyester fiber obtained from the copolyester having no high intrinsic viscosity has a problem that the fiber strength is remarkably lowered. On the other hand, in order to solve the problem, it is disclosed that a tetraalkylammonium salt of sulfoisophthalic acid or a tetraalkylphosphonium salt of sulfoisophthalic acid, that is, a compound (B) is copolymerized with a polyester. Since thermal decomposition tends to occur inside, there is a problem that the thermal decomposition reaction tends to proceed when the amount of copolymerization is increased, and it is still difficult to increase the fiber strength. In the copolymerized polyester of the present invention, the metal salt (A) of sulfoisophthalic acid and the compound (B) are used in combination, the copolymerization amount of both compounds, the copolymerization ratio, the glass transition temperature of the copolymerized polyester and the intrinsic property. The present inventors have found that by setting the viscosity within a specific range, both sufficient dyeability with a cationic dye and high fiber strength can be achieved.

(Glass transition temperature)
The copolyester of the present invention needs to have a glass transition temperature (Tg) in the range of 70 to 85 ° C. in a measuring method by DSC (differential scanning calorimetry) method (temperature increase rate = 20 ° C./min). When the Tg is 70 ° C. or lower, the heat setting property of the polyester fiber obtained by melt spinning is deteriorated, the false twist crimping processability is deteriorated, and the polyester fiber is made of the copolymer polyester. The texture of the fabric obtained from is deteriorated. As a method for lowering the glass transition temperature, adipic acid, sebacic acid, diethylene glycol, polyethylene glycol and the like are copolymerized. In the present invention, these copolymer components satisfy the above glass transition temperature conditions. As long as it is within the range, it may be minutely copolymerized. The range of the preferable value of Tg is 71-82 degreeC, More preferably, it is 75-80 degreeC.

  On the other hand, since it is generally known that the glass transition temperature of polyethylene terephthalate is about 70 to 80 ° C., the copolymer polyester of the present invention may be copolymerized with other copolymer components as described above. Although it is good, it is not preferable to copolymerize a component that significantly lowers the glass transition temperature as a result of copolymerization. In order to set the glass transition temperature within the above range, for example, the type and copolymerization ratio of the compounds that may be copolymerized listed in the description of the above-described copolymerized polyester are appropriately adjusted for copolymerization. I can list them.

(About intrinsic viscosity)
The intrinsic viscosity (solvent: orthochlorophenol, measurement temperature: 35 ° C.) of the copolyester of the present invention is preferably in the range of 0.55 to 1.00 dL / g. When the intrinsic viscosity is 0.55 dL / g or less, the strength of the resulting polyester fiber is insufficient. On the other hand, when the intrinsic viscosity is 1.00 dL / g or more, the melt viscosity becomes too high and melt molding becomes difficult. Further, it is not preferable because the production cost in the polycondensation step of the copolyester is greatly increased by the solid phase polymerization method following the melt polymerization method. The intrinsic viscosity of the cationic dyeable polyester is more preferably in the range of 0.60 to 0.90 dL / g. In order to make the intrinsic viscosity of the copolyester in the range of 0.55 to 1.00 dL / g, it is difficult to adjust the final polymerization temperature and polymerization time during the melt polymerization, or when it is difficult only by the melt polymerization method. Can be appropriately adjusted by solid phase polymerization. In the present invention, the metal salt (A) of sulfoisophthalic acid and the compound (B) are copolymerized with polyethylene terephthalate so as to satisfy the above formulas (1) and (2), and the above-described method is used. It becomes possible to make an intrinsic viscosity into 0.55-1.00 dL / g.

(DEG content)
The diethylene glycol contained in the cationic dyeable polyester in the present invention is preferably 2.5% by weight or less. More preferably, it is 2.0 weight% or less, More preferably, it is 1.40-1.70 weight%. In general, when producing a cationic dyeable polyester, a small amount of alkali metal salt, alkaline earth metal salt, hydroxide is used as a DEG inhibitor to suppress the amount of diethylene glycol (DEG) by-produced in the polyester production process. At least one kind such as tetraalkylphosphonium, tetraalkylammonium hydroxide, and trialkylamine is used, and in the case of the present invention, the total moles of the metal salt (A) of sulfoisophthalic acid and the compound (B) are used. It is preferable to add about 1 to 20 mol% with respect to the amount.

(About the production method of copolyester)
The production of the copolyester in the present invention is not particularly limited, and the metal salt (A) of sulfoisophthalic acid (hereinafter sometimes abbreviated as compound A) and the compound (B) satisfy the condition described in claim 1. Other than this, a conventionally known polyester production method is used. That is, a low polymer is produced by a direct esterification reaction between terephthalic acid and ethylene glycol, or by an ester exchange reaction between an ester-forming derivative of terephthalic acid represented by dimethyl terephthalate and ethylene glycol. Next, this reaction product is produced by heating under reduced pressure in the presence of a polycondensation catalyst to carry out a polycondensation reaction until a predetermined polymerization degree is reached. It is possible to use a production method that is generally known for a method of copolymerizing an aromatic dicarboxylic acid containing sulfoisophthalic acid and / or an ester derivative thereof (metal salt (A) and compound (B) of sulfoisophthalic acid). it can. These compounds can be added to the reaction step at any time from the beginning of the transesterification or esterification reaction to the start of the polycondensation reaction.

  Moreover, the catalyst compound used when performing a normal transesterification reaction can also be used about the catalyst at the time of transesterification. As the polycondensation catalyst, commonly used antimony compounds, germanium compounds, and titanium compounds can be used. Further, a reaction product of a titanium compound and an aromatic polyvalent carboxylic acid or an anhydride thereof, or a reaction product of a titanium compound and a phosphorus compound may be used.

(About other additives)
In addition, the copolymer polyester in the present invention contains a small amount of additives as necessary, for example, antioxidants, fluorescent whitening agents, antistatic agents, antibacterial agents, ultraviolet absorbers, light stabilizers, heat stabilizers, and light-shielding agents. Or a matting agent etc. may be included. In particular, antioxidants and matting agents are particularly preferably added.

(About melt spinning)
There is no restriction | limiting in particular in the spinning method of the copolyester in this invention, A conventionally well-known method is employ | adopted. That is, it is preferable to produce the dried copolyester by melt spinning at a temperature in the range of 270 ° C. to 300 ° C., and the spinning speed of the melt spinning is preferably 400 to 5000 m / min. When the spinning speed is in this range, the polyester fiber obtained has sufficient strength and can be wound stably. Furthermore, it is preferable that the undrawn yarn or the partially drawn yarn obtained by the above-described method is drawn in a range of about 1.2 to 6.0 times in the drawing step. This stretching may be performed after winding the unstretched polyester fiber once, or may be performed continuously without winding. Also, there is no particular limitation on the shape of the die used at the time of spinning, and any of polygons such as circles, triangles / quadrangles, three or more multilobes, C-shaped sections, H-shaped sections, X-shaped sections, and hollow sections. There may be.

EXAMPLES Hereinafter, although an Example is given and this invention is demonstrated concretely, this invention is not restrict | limited to these Examples. In addition, the analysis item etc. in an Example were measured by the method of the following description.
(A) Intrinsic viscosity:
A dilute solution obtained by dissolving a polyester sample in orthochlorophenol at 100 ° C. for 60 minutes was determined from a value measured at 35 ° C. using an Ubbelohde viscometer. The intrinsic viscosity of the tip is ηC, and the intrinsic viscosity of the undrawn yarn after spinning is ηF.
(A) Diethylene glycol (DEG) content:
The polyester sample chip was decomposed using hydrazine hydrate (hydrated hydrazine), and the content of diethylene glycol in the decomposition product was measured using gas chromatography (manufactured by Hewlett-Packard (HP 6850)).
(C) Tensile strength (breaking strength) and tensile elongation (breaking elongation) of polyester fiber
The measurement was performed according to the method described in JIS L1013: 1999 8.5.
(D) Cationic dyeability:
CATHILON BLUE CD-FRLH) 0.2 g / L, CD-FBLH 0.2 g / L (both cation dyeable dyes manufactured by Hodogaya Chemical Co., Ltd.), sodium sulfate 3 g / L, acetic acid 0.3 g / L The sample was dyed at 125 ° C. for 1 hour at a bath ratio of 1:50, and the dyeing rate was determined by the following formula.
Dyeing rate = (OD ₀ −OD ₁ ) / OD ₀
OD ₀ : Absorbance at 576 nm of the dye solution before dyeing OD ₁ : Absorbance at 576 nm of the dye solution after dyeing In the examples of the present invention, those having a dyeing rate of 98% or more were judged to be good dyeability.

[Example 1]
Add 0.03 parts by weight of manganese acetate and 0.12 parts by weight of sodium acetate trihydrate to a mixture of 100 parts by weight of dimethyl terephthalate, 2.9 parts by weight of dimethyl 5-sodium sulfoisophthalate and 60 parts by weight of ethylene glycol. Then, the temperature was gradually raised from 140 ° C. to 240 ° C., and the ester exchange reaction was performed while distilling out the methanol produced as a result of the reaction out of the system. Thereafter, 0.03 part by weight of normal phosphoric acid was added to complete the transesterification reaction.
Thereafter, 0.05 parts by weight of antimony trioxide, 2.0 parts by weight of tetrabutylphosphonate 5-sulfoisophthalate, 0.3 parts by weight of tetraethylammonium hydroxide and 0.003 parts by weight of triethylamine were added to the reaction product. Move to the condensation tank, raise the temperature to 285 ° C., perform the polycondensation reaction at a high vacuum of 30 Pa or less, and perform the reaction when the value of the agitator power in the polycondensation tank reaches a predetermined power or when a predetermined time has elapsed. The chip was finished and chipped according to a conventional method.
The polyester chip thus obtained was dried at 140 ° C. for 5 hours, and then a 330 dtex / 36 filament yarn was prepared at a spinning temperature of 285 ° C. and a winding speed of 400 m / min. A filament drawn yarn was obtained. Details of the production conditions and evaluation results of the copolyester are shown in Table 1.

[Examples 2 to 4, Comparative Examples 1 to 8]
In Example 1, it implemented like Example 1 except having changed the addition amount of sodium 5-sulfoisophthalate and 5-sulfoisophthalate tetrabutylphosphonate so that it might become Table 1. FIG. Details of the production conditions and evaluation results of the copolyester are shown in Table 1.

[Comparative Example 9]
In Example 2, the same procedure as in Example 2 was performed except that the reaction was terminated when the value of the stirrer power in the polycondensation reaction was low. Details of the production conditions and evaluation results of the copolyester are shown in Table 1.

  ADVANTAGE OF THE INVENTION According to this invention, the polyester fiber which has favorable dyeing | staining property by cationic dyeing and has higher intensity | strength than the conventional cationic dyeable polyester can be provided, hold | maintaining the outstanding characteristic of polyester. Its industrial significance is extremely great.

Claims (5)

The main repeating unit is a copolymerized polyester composed of ethylene terephthalate, and a metal salt of sulfoisophthalic acid (A) and a compound (B) represented by the following formula (I) in the acid component constituting the copolymerized polyester Is a copolymer polyester containing the following mathematical formulas (1) and (2) simultaneously, wherein the copolymer polyester has a glass transition temperature in the range of 70 to 85 ° C. A cationic dyeable polyester having an intrinsic viscosity in the range of 0.55 to 1.00 dL / g.

[In the above formula, R represents a hydrogen atom or an alkyl group having 1 to 10 carbon atoms, and X represents a quaternary phosphonium ion or a quaternary ammonium ion. ]
0.3 ≦ A + B <3.0 (1)
0.2 ≦ B / (A + B) ≦ 0.7 (2)
[In the above formula, A is the copolymerization amount (mol%) of the metal salt of sulfoisophthalic acid (A) based on the total acid component constituting the copolyester, and B is the total acid component constituting the copolyester. This represents the copolymerization amount (mol%) of the compound (B) represented by the above formula (I) as a reference. ]   The cationic dyeable polyester according to claim 1, wherein the content of diethylene glycol in the copolymerized polyester is 2.5% by weight or less.   The cationic dyeable polyester according to claim 1 or 2, wherein the metal salt (A) of sulfoisophthalic acid is 5-sodium sulfoisophthalic acid or dimethyl 5-sodium sulfoisophthalate.   The cationic dyeing according to any one of claims 1 to 3, wherein the compound (B) represented by the formula (I) is 5-sulfoisophthalic acid tetrabutylphosphonate or 5-sulfoisophthalic acid dimethyltetrabutylphosphonate. Polyester.   Cationic dyeable polyester fiber obtained by melt spinning the cationic dyeable polyester according to any one of claims 1 to 4.