JP2005336385A - Copolyester, fiber by using the same and method for producing copolyester - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a copolyester capable of being produced without using an antimony compound as a polycondensation catalyst, without substantially containing the antimony, having a good color tone and suitable for a cation-dyeable polyester fiber having an excellent color developing property. <P>SOLUTION: This copolyester is characterized by having ethylene terephthalate units of ≥80 mol % recurring units constituting the polyester, copolymerizing 0.5-8.0 mol % sulfonic acid salt group-containing component based on the total acid component of the copolyester and containing 100-400 ppm solid solution consisting of a magnesium compound with an aluminum compound. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a copolyester suitable for cationic dyeable polyester fibers, a polyester fiber using the copolyester, and a production method for obtaining such a copolyester.

  Polyesters mainly composed of polyethylene terephthalate (hereinafter abbreviated as PET) are not only used for clothing and industrial fibers but also for magnetic tapes and capacitors because of their excellent mechanical and chemical properties. It is widely used as a resin for molded articles such as films or bottles. However, the fiber obtained by melt-spinning a simple polyester does not have good dyeability for use as a fiber for clothing, and since dyeing with disperse dyes is common, there is a problem that the sharpness of the dyed product is poor. was there. Therefore, in order to solve the problem, a copolyester obtained by copolymerizing a sulfonate group-containing component typified by 5-sodium isophthalic acid has been developed. This copolyester is a basic dye (hereinafter referred to as a cationic dye). ) Has been widely used as a molding resin for dyeable polyester fibers for clothing.

  Antimony compounds represented by antimony trioxide are widely used as polycondensation catalysts in the production of polyesters mainly composed of PET, including such copolyesters, because they have excellent catalytic activity and are inexpensive. It is used. However, in polyesters produced using an antimony compound as a polycondensation catalyst, metal antimony is deposited during polycondensation, resulting in darkening and foreign matter in the resulting polyester. At this time, there are problems in production such that foreign matter adheres to the base around the hole and fluff is generated, and there is a problem that the sharpness of the dyed product is inferior. In recent years, polyesters that do not contain antimony are also desired because of problems with safety of antimony that have been pointed out from the environmental viewpoint.

  Attempts have been made to use antimony trioxide as a polycondensation catalyst and to suppress the occurrence of blackening and foreign matters in polyester. For example, a method for suppressing the formation of black foreign substances in polyester by using a compound of antimony trioxide, bismuth and selenium as a polycondensation catalyst has been proposed (see Patent Document 1). Moreover, the method of suppressing precipitation of metal antimony using antimony trioxide containing an oxide of sodium and iron as a polycondensation catalyst is disclosed (see Patent Document 2). However, since these polycondensation catalysts contain antimony, the objective of obtaining a polyester that does not contain antimony cannot be achieved.

  On the other hand, a polycondensation catalyst that replaces the antimony compound has also been studied. In particular, tetraalkoxy titanate has already been proposed, but polyesters produced using this have problems such as remarkable coloring and easy thermal decomposition.

  As a polycondensation catalyst that does not contain antimony and overcomes the problems when using tetraalkoxy titanate, a germanium compound has been put to practical use, but this catalyst is very expensive, There is a problem that the concentration of the catalyst in the reaction system changes due to the fact that it tends to distill out of the reaction system during the polymerization, making it difficult to control the polymerization.

In addition, a polycondensation catalyst has been proposed in which an aluminum compound and a metal compound other than the above can be combined to provide a catalytic activity higher than the combined catalytic activity (Patent Document). 3).
Japanese Patent No. 26650502 (Claims, Effects of Invention) Japanese Patent Laid-Open No. 9-291141 (claims, effects of the invention) JP 2000-302854 A (Means for Solving the Problems)

  The present invention is suitable for a cationic dyeable polyester fiber that can be produced without using an antimony compound as a polycondensation catalyst, is substantially free of antimony, has a good color tone, and has excellent color developability. It is an object of the present invention to provide a copolyester, a polyester fiber using the copolyester, and a method for producing such a copolyester.

  In the production of a copolyester in which a sulfonate group-containing component is copolymerized, the present inventors sequentially used an aluminum compound and a magnesium compound as a polycondensation catalyst following the example of Patent Document 3 described above. When the addition method was tested, a sufficient catalytic effect was exhibited, but the color tone of the obtained copolyester was not satisfactory. Therefore, as a result of intensive studies, a copolyester having a good color tone is obtained by using a solid solution composed of an aluminum compound and a magnesium compound instead of sequentially adding an aluminum compound and a magnesium compound as a polycondensation catalyst. And the fiber obtained from the copolyester has been found to exhibit excellent color by dyeing with a cationic dye, and the present invention has been completed.

That is, the gist of the present invention is as follows.
(1) 80 mol% or more of the repeating units constituting the polyester are ethylene terephthalate units, the sulfonate group-containing component is copolymerized in an amount of 0.5 to 8.0 mol% based on the total acid components of the polyester, and the magnesium compound and aluminum A copolyester comprising 100 to 400 ppm of a solid solution comprising a compound.
(2) The copolymer polyester of (1) above, wherein the sulfonate group-containing component is 5-sodium sulfoisophthalic acid diethylene glycol ester.
(3) The copolymer polyester of (1) above, wherein the sulfonate group-containing component is 5-sodium sulfoisophthalic acid dimethyl ester.
(4) A polyester fiber formed by using the copolyester according to any one of (1) to (3) above.
(5) A method for producing a copolyester, wherein an ethylene terephthalate oligomer and a sulfonate group-containing component are used as starting materials, and a polycondensation reaction is carried out using a solid solution comprising a magnesium compound and an aluminum compound as a polycondensation catalyst. .

  The copolymerized polyester of the present invention is substantially free of antimony and has a low environmental load, is excellent in color tone, and is suitable as a resin for cationic dyeable polyester fibers. In addition, the solid solution consisting of magnesium compound and aluminum compound contained as catalyst residue has a refractive index close to that of PET, so there is no dullness compared to the case of containing an antimony compound, and color development when dyed by fiberization. It is a copolyester resin having excellent properties.

  In addition, the polyester fiber of the present invention is a polyester fiber suitable for clothing having the above-described excellent characteristics due to the use of the copolymer polyester of the present invention.

  In addition, since the production method of the present invention uses a solid solution composed of a magnesium compound and an aluminum compound as a polycondensation catalyst, an appropriate polymerization activity can be obtained as a combined effect of both compounds, so that no antimony compound is used. In addition, the copolyester can be produced efficiently.

  Hereinafter, the present invention will be described in detail.

  In the copolymerized polyester of the present invention, 80 mol% or more of the repeating units constituting the polyester are ethylene terephthalate units, and the sulfonate group-containing component is copolymerized in an amount of 0.5 to 8.0 mol% with respect to the total acid component of the polyester. Is. When the ethylene terephthalate unit is less than 80 mol%, good physical properties peculiar to polyester are liable to be lowered. On the other hand, if the copolymerization ratio of the sulfonate group-containing component is less than 0.5 mol%, the dyeing seat of the cationic dye will be insufficient, and the dyeability of the fiber will be insufficient. On the other hand, when the copolymerization ratio of the sulfonate group-containing component exceeds 8.0 mol%, the melt viscosity of the copolymerized polyester becomes high, so that it is difficult to sufficiently increase the degree of polymerization, and the material strength, for example, when fibers are used. Yarn strength decreases.

  The sulfonate group-containing component to be copolymerized is not particularly limited as long as it is a sulfonate group-containing component having a functional group that reacts with the polyester. For example, 5-sodium sulfoisophthalic acid, 5-potassium sulfone Dicarboxylic acids such as isophthalic acid, 5-lithium sulfoisophthalic acid, sodium sulfonaphthalenedicarboxylic acid, 2-sodium sulfoterephthalic acid and their alkyl and / or hydroxyalkyl esters, and oxycarboxylic acids such as sodium sulfobenzoic acid and their alkyl Examples include esters. Of these, 5-sodium sulfoisophthalic acid diethylene glycol ester and 5-sodium sulfoisophthalic acid dimethyl ester are particularly preferable from the viewpoints of color developability with a cationic dye, operability during melt spinning, and cost.

  The copolymerized polyester of the present invention may be copolymerized with a copolymerized component other than the sulfonate group-containing component as long as the effects of the present invention are not impaired. Examples of such copolymer components include aromatic dicarboxylic acid components such as isophthalic acid, phthalic anhydride, and naphthalenedicarboxylic acid, fats such as succinic acid, glutaric acid, adipic acid, sebacic acid, dodecanedicarboxylic acid, and dimer acid. Group dicarboxylic acid component, 1,2-propylene glycol, 1,3-propylene glycol, triethylene glycol, tetraethylene glycol, 1,2-butylene glycol, 1,3-butylene glycol, 2,3-butylene glycol, 1, Aromatic glycol components such as aliphatic glycol components such as 4-butylene glycol, alicyclic glycol components such as 1,4-cyclohexanedimethanol, polyalkylene ether components such as polyethylene glycol, and alkylene oxide adducts of bisphenol A and bisphenol S Ingredients, 4-hydroxybenzoic acid, ε-caprolacto Hydroxycarboxylic acid component and the like.

  The copolymerized polyester of the present invention contains 100 to 400 ppm of a solid solution composed of a magnesium compound and an aluminum compound. Since the solid solution composed of the magnesium compound and the aluminum compound is the one used in the polycondensation catalyst in the process of producing the copolymer polyester of the present invention, it depends on the amount used as the polycondensation catalyst. Contained. In addition, the copolyester of the present invention is substantially free of antimony because a conventional antimony compound is not used as a polycondensation catalyst in the production process. Therefore, when the content of the solid solution composed of the magnesium compound and the aluminum compound is less than 100 ppm, the action as a polycondensation catalyst is insufficient, so that the degree of polymerization of the copolymer polyester of the present invention is increased to a range suitable for fiberization. It will not be. On the other hand, when it exceeds 400 ppm, the color tone of the copolyester deteriorates, or the solid solution composed of the magnesium compound and the aluminum compound aggregates in the copolyester to form coarse particles, and the pack pressure increases when used for spinning. This may cause troubles such as thread breakage.

  In addition, about a polymerization degree suitable for said fiberization, intrinsic viscosity can be used as a parameter | index. That is, the intrinsic viscosity of the copolymerized polyester of the present invention is preferably in the range of 0.40 to 0.80, and particularly preferably in the range of 0.45 to 0.75. If the intrinsic viscosity is less than 0.40, the strength tends to be insufficient when the fiber is used, which is not preferable. On the other hand, the range exceeding 0.80 is not preferable because melt spinning becomes difficult.

  The solid solution composed of an aluminum compound and a magnesium compound used in the present invention is a solid in which each compound is uniformly dissolved. In this solid solution, the aluminum / magnesium element mass (molar) ratio is preferably 0.1 to 10.0, more preferably 0.2 to 5.0, as the ratio of aluminum / magnesium.

  Although it does not specifically limit as an aluminum compound which comprises the above-mentioned solid solution, For example, aluminum hydroxide, aluminum hydroxide chloride, aluminum formate, aluminum acetate, aluminum propionate, aluminum oxalate, aluminum acrylate, stearic acid Examples include carboxylates such as aluminum and aluminum benzoate, and inorganic salts such as aluminum chloride, aluminum carbonate, and aluminum phosphate, aluminum methoxide, aluminum ethoxide, aluminum n-propoxide, and aluminum n-butoxide. Examples include aluminum alkoxide, aluminum acetylacetonate, aluminum acetylacetate, and organic alcohols such as trimethylaluminum and triethylaluminum. Minium compounds and partial hydrolysates of these organoaluminum compounds are included, and aluminum oxide, metallic aluminum, and the like are also included. Of these, carboxylates and inorganic acid salts are preferred, and among these, aluminum hydroxide, aluminum acetate, and aluminum chloride are particularly preferred.

  On the other hand, examples of the magnesium compound include magnesium hydroxide, magnesium carbonate, magnesium acetate, magnesium acetylacetonate, and carboxylic acids other than acetic acid. Among these, magnesium hydroxide and magnesium carbonate are particularly preferable.

  In addition, as a solid solution which consists of an aluminum compound and a magnesium compound in this invention, the thing comprised by selecting 2 or more types in either one or both of an aluminum compound and a magnesium compound may be sufficient.

  In addition, in the solid solution composed of the aluminum compound and the magnesium compound in the present invention, a compound of a metal other than magnesium and aluminum (other metals) may be dissolved as necessary. It is preferable that 70% or more of the mass of the solid solution is occupied by the aluminum compound and the magnesium compound. Examples of other metals include zinc, titanium, tin, cobalt, manganese, niobium, tantalum, tungsten, indium, zirconium, hafnium, silicon, iron, nickel, and gallium.

  Among the solid solutions composed of an aluminum compound and a magnesium compound in the present invention, particularly preferred are solid solutions composed of aluminum hydroxide, magnesium hydroxide and magnesium carbonate. In addition, a solution in which a small amount of zinc oxide is dissolved therein is also suitable.

  Titanium oxide particles may be added to the copolyester of the present invention. Titanium oxide is commonly used as a matting agent and white pigment for polyester. However, the addition of an appropriate amount of titanium oxide to the copolymerized polyester of the present invention improves the whiteness of the fiber. It is preferable in that a fabric having a good color tone can be obtained. The addition amount of titanium oxide is preferably 0.005 to 5.0 parts by mass with respect to 100 parts by mass of the copolyester (not including the mass of titanium oxide). If the added amount of titanium oxide is less than 0.005 parts by mass, it is difficult to obtain the effect of improving the whiteness. On the other hand, if it exceeds 5.0% by mass, the appearance of the copolyester tends to be yellowish. Therefore, secondary aggregation of the titanium oxide particles is likely to occur, the coarse particles are likely to cause problems such as an increase in pack pressure and wear of the guide during spinning, and the operability during melt spinning tends to decrease, such being undesirable. As said titanium oxide particle, an average particle diameter of 1.0 micrometer or less is preferable, and a 0.1-0.6 micrometer thing is especially preferable.

  In addition, as long as the effects of the present invention are not impaired, antioxidants such as hindered phenol compounds, phosphorus compounds and sulfur compounds, color improvers such as cobalt compounds, fluorescent agents and dyes, cerium oxide Various additives such as a light-proofing agent such as may be added to the copolymerized polyester of the present invention.

  The copolyester of the present invention is suitable for a cationic dyeable fiber, and the polyester fiber of the present invention can be obtained by melt spinning using this in a usual manner. For example, the copolyester pellets of the present invention are dried by a conventional method, supplied to an ordinary melt spinning machine base, melt-spun at a temperature higher than the melting point of the copolyester by 20 ° C., and a speed of 1000 to 4000 m / min. Then, it is once wound as an unstretched yarn or semi-unstretched yarn, or it is continuously stretched 1.5 to 3.5 times without being spun off, and heat treatment is performed at 80 to 180 ° C. to obtain a target fiber.

  The polyester fiber of the present invention may be a composite fiber using other resins in addition to the copolyester of the present invention, and the form of the fiber may be a long fiber or a short fiber. It can also be used after being subjected to post-processing such as processing, false twisting, or treatment with a chemical solution.

  Further, it goes without saying that the polyester fiber of the present invention may contain titanium oxide particles and various additives that can be added to the copolymer polyester of the present invention as described above. And various additives may be added during melt spinning.

  Next, the manufacturing method which can manufacture the above copolyester is demonstrated.

  The production method of the present invention is a method for producing a copolyester in which a sulfonate group-containing component is copolymerized, and is desired by performing polycondensation using an ethylene terephthalate oligomer and a sulfonate group-containing component as starting materials. The copolyester is produced by using a solid solution composed of the magnesium compound and the aluminum compound as described above as a polycondensation catalyst. In the production method of the present invention, an appropriate polymerization activity is obtained by using a solid solution composed of a magnesium compound and an aluminum compound, instead of adding a magnesium compound and an aluminum compound as separate catalyst substances to the system, and aluminum. The problem that minute foreign matters such as insoluble decomposition products are generated in the copolyester or the color tone is not excellent, which occurs when the compound and the magnesium compound are sequentially added, is solved.

  In the production method of the present invention, the amount of the solid solution comprising the magnesium compound and the aluminum compound as the polycondensation catalyst is 100 to 400 ppm with respect to the total amount of the copolyester obtained by polycondensation. preferable. When the amount of the solid solution used is less than 100 ppm, the activity as a polycondensation catalyst is insufficient, and it is difficult to sufficiently increase the degree of polymerization of the copolymer polyester, and a copolymer polyester having an intrinsic viscosity suitable for fiberization is obtained. Since it is hard to be done, it is not preferable. On the other hand, if the amount used exceeds 400 ppm, the color tone of the resulting copolymerized polyester deteriorates, or the solid solution aggregates in the copolymerized polyester to become coarse particles, increasing the pack pressure when used for melt spinning, Since it may cause troubles such as thread breakage, it is not preferable.

  Below, the manufacturing method of this invention is demonstrated in detail based on a preferable aspect.

  In the production method of the present invention, an ethylene terephthalate oligomer and then a sulfonate group-containing component are charged as a starting material into a suitable reaction vessel. Here, the timing and method of adding the sulfonate group-containing component are not particularly limited, but in order to improve the dispersibility of the sulfonate group-containing component, ethylene is added before the addition of the sulfonate group-containing component. The terephthalate oligomer is preferably depolymerized using ethylene glycol (hereinafter abbreviated as EG). As the amount of EG used when depolymerizing the ethylene terephthalate oligomer, the ethylene terephthalate oligomer is preferably 1 to 50 parts by mass with respect to 100 parts by mass, and 3 to 30 parts by mass. More preferably. When the amount of EG used is less than 1 part by mass, depolymerization of the ethylene terephthalate oligomer tends to be insufficient, and foreign substances derived from the sulfonate group-containing component are likely to be generated, which is not preferable. On the other hand, when it exceeds 50 parts by mass, the content of diethylene glycol (hereinafter abbreviated as DEG) in the resulting copolymerized polyester tends to increase, and as a result, the heat resistance of the copolymerized polyester decreases. In addition, when the fiber is formed, the fiber tends to be inferior in false twisting, which is not preferable.

  Moreover, as temperature for depolymerizing an ethylene terephthalate oligomer, 210-260 degreeC is preferable. A depolymerization temperature of less than 210 ° C. is not preferable because the ethylene terephthalate oligomer is solidified and cannot be depolymerized. On the other hand, if the depolymerization temperature exceeds 260 ° C., the content of DEG in the resulting copolyester tends to increase, such being undesirable.

  The time for depolymerizing the ethylene terephthalate oligomer is preferably 5 to 90 minutes, more preferably 15 to 60 minutes. If the depolymerization time is less than 5 minutes, the depolymerization of the ethylene terephthalate oligomer tends to be insufficient, and foreign substances derived from the sulfonate group-containing component tend to be generated, which is not preferable. On the other hand, if it exceeds 90 minutes, the content of DEG in the resulting copolyester tends to increase, such being undesirable.

  In addition to the ethylene terephthalate oligomer as one starting material, which is preferably depolymerized as described above, a sulfonate group-containing component as the other starting material is charged. When the sulfonate group-containing component is added, it is preferably added in the form of an EG solution or a slurry.

  In the production method of the present invention, when an alkali metal compound is added at the same time or before the introduction of the sulfonate group-containing component, it is possible to suppress the by-production of DEG, and a high-quality copolymer polyester is obtained. Therefore, it is preferable. Examples of such alkali metal compounds include hydroxides, organic carboxylates, alcoholates, inorganic weak acid salts, etc., specifically sodium, potassium, lithium hydroxides, formates, acetates, etc. Aliphatic carboxylates, methylates, ethylates, butyrates, carbonates, bicarbonates, borates and the like can be mentioned. Among these, sodium acetate and lithium acetate are particularly preferably used because they have a high effect of suppressing the by-production of DEG.

The addition amount of the alkali metal compound is preferably 5 × 10 ^{−4 to} 5 × 10 ⁻³ with respect to 1 mol of the acid component of the polyester. If the amount of the alkali metal compound added is less than 5 × 10 ⁻⁴ mol relative to 1 mol of the acid component of the polyester, the amount of DEG produced as a by-product during the reaction increases, which is not preferable. On the other hand, when it exceeds 5 × 10 ⁻³ mol, an insoluble component is easily generated in the polyester derived from the alkali metal atom, which is not preferable.

  If the sulfonate group-containing component is added before the alkali metal compound is added, the amount of DEG produced as a by-product during the reaction tends to increase. Therefore, it is preferable that the alkali metal compound is added at the same time as or before the addition of the sulfonate group-containing component.

  After adding the ethylene terephthalate oligomer and the sulfonate group-containing component as described above, a solid solution composed of an aluminum compound and a magnesium compound as a polycondensation catalyst is added, and the addition method is particularly limited. Although it is not a thing, it is preferable to add the said solid solution as a slurry disperse | distributed in the dispersion medium. At this time, the content of the solid solution in the slurry is preferably 0.5 to 3.0% by mass. If it is less than 0.5% by mass, the amount of slurry added is increased, and a large amount of distillate is produced during polymerization, which is not preferable because it tends to increase costs. On the other hand, if it exceeds 3.0% by mass, the solid solution tends to agglomerate when the slurry is added to the system, the solid solution becomes coarse particles in the copolyester, and when the polyester fiber is spun, the pack pressure increases or the yarn breaks. This is not preferable because it tends to cause troubles.

  Examples of the dispersion medium used for the solid solution slurry include EG, 1,2-propylene glycol, 1,3-propylene glycol, DEG, triethylene glycol, tetraethylene glycol, 1,2-butylene glycol, and 1,3-butylene. Glycol, 2,3-butylene glycol, 1,4-butylene glycol, and the like. Among these, EG is particularly preferable.

  Further, in order to prevent the solid solution from agglomerating into coarse particles, it is preferable to add a predetermined amount of the solid solution to a dispersion medium such as EG and mix with stirring, followed by ultrasonic treatment. The frequency of the ultrasonic wave at this time may be in a normal frequency range, and for example, processing in the range of about 20 kHz to 100 kHz can be employed. As an oscillation source for generating ultrasonic waves, known means may be used, and examples thereof include a piezoelectric vibrator using crystal, an electrostrictive oscillator using nickel or ferrite, and the like. In addition, the ultrasonic treatment time is preferably in the range of 0.5 to 5.0 hours.

  If the method of the present invention is described in more detail, for example, it can be carried out as follows.

  First, as a preparatory stage, to obtain ethylene terephthalate oligomer as a starting material, existence of bis- (β-hydroxyethyl) terephthalate or its low polymer (ethylene terephthalate oligomer) at 230-250 ° C under nitrogen gas pressure A slurry consisting of EG and terephthalic acid (hereinafter abbreviated as TPA), with a mass ratio of 1.1 to 2.0, is added to the esterification reaction tank, and esterification is carried out in a residence time of 7 to 8 hours. The reaction is obtained continuously. The esterification reaction product thus obtained becomes an ethylene terephthalate oligomer among the starting materials referred to in the present invention.

  Next, this esterification reaction product, that is, ethylene terephthalate oligomer is transferred to a polymerization reactor, and 1 to 50 parts by mass of EG is added to 100 parts by mass of ethylene terephthalate oligomer, and depolymerization takes 15 to 60 minutes. I do. After adding an alkali metal compound, a predetermined amount of a sulfonate group-containing component (EG solution or slurry) is added, and a solid solution (EG slurry) composed of a magnesium compound and an aluminum compound is added as a polycondensation catalyst. The temperature of the polymerization reactor is raised to 260 to 280 ° C., and a polycondensation reaction is performed under a reduced pressure of 0.01 to 13.3 hPa until a predetermined intrinsic viscosity is obtained.

  In the production method of the present invention, for example, when a dialkylene glycol ester typified by 5-sodium sulfoisophthalic acid diethylene glycol ester (hereinafter abbreviated as SIPG) is used as the sulfonate group-containing component, as described above, After depolymerizing the ethylene terephthalate oligomer with a predetermined amount of EG, an alkali metal compound is added, and SIPG is introduced into the system in the form of an EG solution having a concentration of 30 to 40% by mass, and then the above polycondensation catalyst. It is preferable to carry out a procedure in which a predetermined amount of solid solution is charged in the form of EG slurry and pressure reduction is started. For example, when dimethyl ester represented by 5-sodium sulfoisophthalic acid dimethyl ester (hereinafter abbreviated as SIPM) is used as the sulfonate group-containing component, the ethylene terephthalate oligomer is dissolved with a predetermined amount of EG. After polymerization, an alkali metal compound is added, SIPM is added in the form of an EG slurry with a concentration of 30 to 40% by mass, and then a predetermined amount of the above solid solution as a polycondensation catalyst is charged in the form of EG slurry. Then, it is preferable to carry out by the procedure of starting depressurization.

Next, the present invention will be specifically described with reference to examples. In addition, the measuring method of the characteristic value in an Example and a comparative example is as follows. However, (a)-(e) measured about the pellet of the copolymer polyester, (f) and (g) measured about the polyester fiber obtained using the copolymer polyester.
(a) Intrinsic viscosity ([η])
Phenol / tetrachloroethane = 1/1 (mass ratio) was used as a solvent, and the temperature was measured at 20 ° C.
(b) Content of solid solution consisting of magnesium compound and aluminum compound Using a fluorescent X-ray analyzer (3270, manufactured by Rigaku Corporation), the content of aluminum element in the polyester resin was measured, and this was determined as the amount of aluminum element in the solid solution. Converted from the ratio, the solid solution content was determined.
(c) Diethylene glycol content (D%)
After the obtained copolyester was hydrolyzed with alkali, the amount of EG and DEG (number of moles) was quantified using a gas chromatograph (GC-9A manufactured by Shimadzu Corporation), and the amount of EG and DEG (number of moles) The percentage (%) of the substance amount (in moles) of DEG relative to the sum of
(d) Color tone of copolymerized polyester Color tone was measured using a color difference meter (ND-Σ80 type manufactured by Nippon Denshoku Industries Co., Ltd.). Judgment of the color tone was performed by Hunter's Lab color system. L value is lightness (larger value is brighter), a value is red-green hue (+ is reddish,-is greenish), b value is yellow-blue hue (+ is yellowish,-is Blue). As the color tone of the copolyester, the larger the L value, the closer the a value is to 0, and the smaller the b value, the better as long as it is not extremely small. Here, L value and b value were measured. The L value was 65 or more and the b value was 5.0 or less.
(e) Content of titanium oxide Using a fluorescent X-ray analyzer (3270, manufactured by Rigaku Corporation), the content of titanium element is measured, and all of the titanium element in the copolyester is present in the form of titanium dioxide. Assuming that.
(f) Fiber strength (cN / dtex)
A polyester fiber (filament yarn) cut to a length of 50 cm is subjected to a tensile test at a speed of 50 cm / min using a universal testing machine (Orientic Tensilon RTC-1210 type). It was obtained from the strain curve. Here, 2.5 cN / dtex or more was considered acceptable.
(G) Dyeability (L value after dyeing)
Polyester fibers (filament yarns) were knitted and refined at 60 ° C. for 20 minutes, then dyed at 130 ° C. for 60 minutes and air-dried under the following dyeing conditions. Next, after heat setting for 1 minute at 150 ° C. using a small pin tenter, a four-layer sample piece was prepared.

The L value of this sample piece was measured with a color difference meter (CR-100 manufactured by Minolta Co., Ltd.) to evaluate the dyeability. The lower the L value, the deeper the color of the fiber, and the more dye is exhausted into the fiber. Therefore, it was judged that the lower the L value, the better the dyeability, and those having an L value after dyeing of 35 or less were accepted.
(Dyeing conditions)
Dye Astrazone Blue 0.5% omf
Leveling agent Acetic acid 0.2mL / L
Sodium acetate 0.2g / L
Bath ratio 1:50

Example 1
A slurry with a TPA / EG mass ratio (1 / mole) of 1 / 1.6 is continuously fed to an esterification reactor containing ethylene terephthalate oligomer, under the conditions of a temperature of 250 ° C., a pressure of 0.1 MPa, and a residence time of 8 hours. Then, an esterification reaction was performed to continuously obtain an ethylene terephthalate oligomer having a reaction rate of 95%.

49.0 kg of this ethylene terephthalate oligomer was transferred to a polycondensation reactor, 4.0 kg of EG was added, and a depolymerization reaction was carried out at 250 ° C. for 40 minutes. Next, after adding 0.3 kg of EG slurry prepared so that the concentration of titanium oxide (KA-30 manufactured by Titanium Industry Co., Ltd.) is 35% by mass, EG prepared so that the concentration of lithium acetate is 5% by mass. 0.8 kg of the solution (the amount of lithium acetate corresponding to 1 mol of the acid component of the polyester corresponds to 1.5 × 10 ⁻³ mol) was added. Next, 7.4 kg of an EG solution prepared so that the concentration of SIPG is 30% by mass (the amount of copolymerization of SIPG corresponds to 2.5 mol% in the total acid components constituting the polyester) is added, and water is added as a catalyst. Prepared so that the concentration of solid solution (HT-P manufactured by Sakai Chemical Industry Co., Ltd.) with aluminum / magnesium hydroxide and magnesium carbonate, with an aluminum / magnesium substance amount (molar) ratio of 0.4, was 1.5% by mass. 0.8 kg of EG slurry (corresponding to 250 ppm with respect to the amount of copolymerized polyester in which the amount of solid solution used is obtained) was added. Thereafter, pressure reduction was started in parallel with the temperature increase, the temperature in the polycondensation reaction can was 275 ° C. after 30 minutes, and the pressure was 1.2 hPa or less after 60 minutes. Then, while maintaining the temperature (275 ° C.) and reduced pressure (1.2 hPa or less) conditions, the polycondensation reaction is performed for 2 hours with stirring, and the copolymerized polyester of the present invention is obtained by discharging and pelletizing by a conventional method. Obtained in the form of pellets.

  The copolyester pellets obtained above were dried by a conventional method and then spun using a conventional melt spinning apparatus. At this time, the spinning temperature was set to 300 ° C., the discharge rate was set to 39.6 g / min, and the mixture was filtered through a filter with a diameter of 100 mm and a mesh opening of 2000 mesh (American type) installed in the nozzle pack. Spinning from a nozzle having 36 holes with / D = 2, the partially undrawn yarn was scraped off at a speed of 3300 m / min. Next, this partially undrawn yarn was supplied to a drawing machine, preheated at 80 ° C., drawn 1.5 times while being in contact with a heat plate at a temperature of 150 ° C., and then heat-treated to obtain an 83 dtex / 36 f filament yarn. As a result, the polyester fiber of the present invention was obtained.

Example 2 and Comparative Example 1
The same procedure as in Example 1 was conducted except that the amount of SIPG copolymerized, the amount of titanium oxide added, and the amount of solid solution as a polycondensation catalyst were changed as shown in Table 1.

Example 3
49.8 kg of ethylene terephthalate oligomer obtained in the same manner as in Example 1 was transferred to a polycondensation reaction can, and 4.0 kg of EG was added, followed by depolymerization reaction at 250 ° C. for 40 minutes. Next, after adding 0.5 kg of EG slurry prepared so that the concentration of titanium oxide (KA-30 manufactured by Titanium Industry Co., Ltd.) is 35% by mass, EG prepared so that the concentration of lithium acetate is 5% by mass. 0.8 kg of the solution (the amount of lithium acetate with respect to 1 mol of the acid component of the polyester corresponds to 1.5 × 10 ⁻³ mol) was added. Next, 2.0 kg of EG slurry prepared so that the concentration of SIPM is 30% by mass (the copolymerization amount of SIPM corresponds to 0.8 mol% in the total acid components constituting the polyester) is added, and water is used as a catalyst. EG slurry prepared from aluminum oxide, magnesium hydroxide, and magnesium carbonate, with a solid solution (HT-P manufactured by Sakai Chemical Industry Co., Ltd.) with an aluminum / magnesium substance amount (molar) ratio of 0.4. 0.8 kg (corresponding to 150 ppm with respect to the amount of copolymerized polyester in which the amount of solid solution used is obtained) was added. Thereafter, pressure reduction was started in parallel with the temperature increase, the temperature in the polycondensation reaction can was 275 ° C. after 30 minutes, and the pressure was 1.2 hPa or less after 60 minutes. Then, while maintaining the temperature (275 ° C.) and reduced pressure (1.2 hPa or less) conditions, the polycondensation reaction is performed for 2 hours with stirring, and the copolymerized polyester of the present invention is obtained by discharging and pelletizing by a conventional method. Obtained in the form of pellets. Moreover, it carried out similarly to Example 1, and obtained the polyester fiber of this invention using the pellet of said copolyester.

Comparative Examples 2-4
The same procedure as in Example 3 was carried out except that the copolymerization amount of SIPM, the addition amount of titanium oxide, and the addition amount of the solid solution as the polycondensation catalyst were changed as shown in Table 1.

Example 4
As a polycondensation catalyst, in the solid solution described in Example 1 composed of aluminum hydroxide, magnesium hydroxide and magnesium carbonate, the zinc oxide (zinc) / (aluminum + magnesium) substance amount (molar) ratio is 0.05. The solution was used in the same manner as in Example 3 except that the solid solution was used and the addition amount was changed as shown in Table 1.

Comparative Example 5
Example 3 except that the polycondensation catalyst was used in an amount corresponding to 150 ppm with respect to the copolyester from which aluminum acetate can be obtained and magnesium acetate in an amount corresponding to 105 ppm with respect to the polyester, and these were added sequentially. It carried out like.

Comparative Example 6
As a polycondensation catalyst, it carried out like Example 3 except having added in the quantity used as 250 ppm with respect to the copolyester which can obtain antimony trioxide.

  Table 1 summarizes the characteristic values and evaluation results of the copolyesters and polyester fibers obtained in Examples 1 to 4 and Comparative Examples 1 to 6.

  As is clear from Table 1, in Examples 1 to 4, copolymer polyesters having good color tone and intrinsic viscosity suitable for fiberization were obtained. As a result of melt spinning these copolyesters, polyester fibers having sufficient strength and good dyeability when dyed with a cationic dye could be obtained.

  On the other hand, Comparative Examples 1-6 had the following problems.

  In Comparative Example 1, a copolymer polyester having a sufficient intrinsic viscosity could not be obtained because the amount of copolymerization of SIPG as a sulfonate group-containing component was too large. As a result, yarn breakage occurred frequently during melt spinning, and fibers could not be obtained.

  In Comparative Example 2, since the copolymerization amount of SIPM, which is a sulfonate group-containing component, was too small, when the obtained copolymer polyester was melt-spun into a polyester fiber, it was inferior in dyeability with a cationic dye. It became a thing.

  In Comparative Example 3, a copolyester having a sufficient intrinsic viscosity could not be obtained because the content of the solid solution composed of the magnesium compound and the aluminum compound was too small. As a result, the strength of the polyester fiber obtained by melt spinning was low and was not practical.

  Since the comparative example 4 had too much content of the solid solution which consists of a magnesium compound and an aluminum compound, the color tone of obtained copolymer polyester worsened. Moreover, due to the coarse particles that appear to be due to the solid solution, yarn breakage occurred frequently during melt spinning, and fibers could not be obtained.

  Since Comparative Example 5 did not use a solid solution composed of an aluminum compound and a magnesium compound as a polycondensation catalyst, but separately added separate aluminum compounds and magnesium compounds, the copolymer polyester obtained was used. The color tone of became worse. As a result, the polyester fiber obtained by melt spinning was inferior in color developability when dyed with a cationic dye.

In Comparative Example 6, since antimony trioxide was used as the polycondensation catalyst, the color tone of the obtained copolyester deteriorated. As a result, the polyester fiber obtained by melt spinning was inferior in color developability when dyed with a cationic dye.

Claims (5)

  80 mol% or more of the repeating unit constituting the polyester is an ethylene terephthalate unit, and the sulfonate group-containing component is copolymerized in an amount of 0.5 to 8.0 mol% with respect to the total acid component of the polyester. A copolyester characterized by comprising 100 to 400 ppm of a solid solution.   The copolymerized polyester according to claim 1, wherein the sulfonate group-containing component is 5-sodium sulfoisophthalic acid diethylene glycol ester.   The copolymerized polyester according to claim 1, wherein the sulfonate group-containing component is 5-sodium sulfoisophthalic acid dimethyl ester.   The polyester fiber formed using the copolyester in any one of Claims 1-3. A method for producing a copolyester, characterized in that an ethylene terephthalate oligomer and a sulfonate group-containing component are used as starting materials, and a polycondensation reaction is carried out using a solid solution comprising a magnesium compound and an aluminum compound as a polycondensation catalyst.