Polyester resin, fiber, and method for producing polyester resin

Abstract

To provide a polyester resin from which a fiber that is excellent in dyeability with a cation dye and is also excellent in yarn quality characteristics (strength and extensibility) can be obtained with good operability.SOLUTION: A polyester resin contains a dicarboxylic acid component and a glycol component. In the polyester resin, the dicarboxylic acid component contains a terephthalic acid as a main component and an aromatic dicarboxylic acid having a metal sulfonate group, the glycol component contains ethylene glycol as a main component and contains diethylene glycol and triethylene glycol, and a content of the triethylene glycol in the glycol component is 0.5 mol% or more and 5.5 mol% or less.SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates to a polyester resin, a fiber, and a method for producing the polyester resin. [Background technology]

[0002] Polyester resins, such as polyethylene terephthalate (PET), polybutylene terephthalate (PBT), and polyethylene naphthalate (PEN), have excellent mechanical and chemical properties and are used in a wide range of fields (for example, fibers for clothing and industrial materials, films and sheets for packaging and magnetic tape, hollow molded bottles, casings for electrical and electronic components, and other engineering plastic molded products).

[0003] Antimony-based metal catalysts have been known as polycondensation catalysts used in the polycondensation of polyester resins. Antimony-based catalysts are inexpensive and have excellent catalytic activity, but when used in an amount sufficient to achieve a practical polymerization rate, metallic antimony precipitates during polycondensation, causing blackening or the generation of foreign matter in the polyester resin, which can cause production problems or surface defects in processed products.

[0004] Therefore, copolymerized polyesters suitable for polyester fibers having excellent cationic dyeability, which are produced without using an antimony-based catalyst as a polycondensation catalyst, have been investigated (for example, Patent Document 1). [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Application Laid-Open No. 2006-63215 Summary of the Invention [Problem to be solved by the invention]

[0006] In Patent Document 1, a metal catalyst such as magnesium is used, but there are still problems such as reduced operability due to metal precipitation during polymerization and poor color tone. For this reason, polyester resins using organic catalysts are also being studied. In recent years, from the viewpoint of environmental consideration, there has been a demand for polyester resins that use organic catalysts and that can give polyester fibers that are excellent in dyeability with cationic dyes and that are also excellent in yarn quality characteristics such as strength and elongation.

[0007] An object of the present invention is to provide a polyester resin which, using an organic catalyst, can give polyester fibers which are excellent in dyeability with cationic dyes and also in strength and elongation properties. [Means for solving the problem]

[0008] As a result of extensive research to solve the above-mentioned problems, the present inventors have found that a polyester resin of the present invention, which contains an aromatic dicarboxylic acid having a metal sulfonate group as a dicarboxylic acid component, and a glycol component containing diethylene glycol and triethylene glycol, wherein the content of triethylene glycol in the glycol component is within a specific range, has excellent dyeability with cationic dyes and also has excellent strength and elongation properties when made into fibers, thereby arriving at the present invention.

[0009] That is, the gist of the present invention is as follows: (1) (9) As stated above. (1) A polyester resin containing a dicarboxylic acid component and a glycol component, wherein the dicarboxylic acid component contains terephthalic acid as a main component and also contains an aromatic dicarboxylic acid having a metal sulfonate group, and the glycol component contains ethylene glycol as a main component and also contains diethylene glycol and triethylene glycol, and the content of triethylene glycol in the glycol component is 0.5 mol% or more and 5.5 mol% or less. The content of sulfur components other than aromatic dicarboxylic acids having metal sulfonate groups is 5 to 100 ppm. A polyester resin characterized by: (2) The polyester resin according to (1), wherein the glycol component contains diethylene glycol in an amount of 2.5 mol % or more. (3) The polyester resin according to (1) or (2), wherein the glycol component contains tetraethylene glycol and the content of tetraethylene glycol in the glycol component is 2.0 mol % or less. (4) The polyester resin according to (3), wherein the total content of triethylene glycol and tetraethylene glycol in the glycol component is 7.0 mol % or less. (5) The polyester resin according to any one of (1) to (4), wherein the content of the aromatic dicarboxylic acid having a metal sulfonate group in the dicarboxylic acid component is 0.5 to 5.5 mol %. (6) The polyester resin according to any one of (1) to (5), wherein the dicarboxylic acid component contains an aliphatic dicarboxylic acid having 5 to 10 carbon atoms, and the content of the dicarboxylic acid component is 2 to 18 mol %. (7) The polyester resin according to any one of (1) to (6), wherein the dicarboxylic acid component contains isophthalic acid in an amount of 8 to 15 mol %. (8) (1)~( 7 ) A fiber made of the polyester resin according to any one of the above. (9) (1)~( 7 ) a method for producing the polyester resin according to any one of the above items (1) to (4), Other than aromatic dicarboxylic acids having metal sulfonate groups A method for producing a polyester resin, comprising the step of adding an organic sulfonic acid compound and heating at a temperature of 240°C or higher for 5 to 120 minutes under normal pressure or pressure to carry out an etherification reaction of a glycol component. [Effects of the Invention]

[0010] The polyester resin of the present invention uses an organic sulfonic acid compound as a catalyst, and can produce polyester fibers that are excellent in dyeability with cationic dyes, strength, and elongation, with good operability. DETAILED DESCRIPTION OF THE INVENTION

[0011] The polyester resin of the present invention will be described in detail below. The polyester resin of the present invention contains a dicarboxylic acid component and a glycol component. The dicarboxylic acid component is mainly composed of terephthalic acid, and further contains an aromatic dicarboxylic acid having a metal sulfonate group. That is, the acid component is mainly composed of terephthalic acid, and the aromatic dicarboxylic acid having a metal sulfonate group is a copolymerization component. By copolymerizing the aromatic dicarboxylic acid having a metal sulfonate group, it is possible to impart dyeability with cationic dyes to the polyester resin.

[0012] When the total amount of all acid components constituting the polyester is taken as 100 mol %, the content of the aromatic dicarboxylic acid having a metal sulfonate group is preferably 0.5 to 5.5 mol %, more preferably 0.8 to 5.0 mol %. If the content of aromatic dicarboxylic acid having a metal sulfonate group is less than 0.5 mol %, the dyeing sites for the cationic dye (the number of reactive groups that react with the cationic dye) in the entire polymer will be insufficient, and sufficient dyeability may not be obtained when the resulting polyester resin is used to make fibers.

[0013] On the other hand, if the content exceeds 5.5 mol%, the melt viscosity of the polyester tends to be too high in the polycondensation step, making it difficult to sufficiently increase the degree of polymerization, which may result in a decrease in the strength of the material (e.g., the strength of the yarn when made into a fiber). Furthermore, since the aromatic dicarboxylic acid having a metal sulfonate group acts as a catalyst in the etherification step described below, by setting the content within the above range, the contents of ethylene glycol and triethylene glycol in the glycol component can be set within specific ranges.

[0014] Examples of aromatic dicarboxylic acids having a metal sulfonate group include 5-sodium sulfoisophthalic acid, 5-potassium sulfoisophthalic acid, 5-lithium sulfoisophthalic acid, sodium sulfonaphthalenedicarboxylic acid, sodium sulfophenyldicarboxylic acid, and 5-sodium sulfoterephthalic acid. In the present invention, 5-sodium sulfoisophthalic acid is preferably used in terms of color development with cationic dyes, operability during melt spinning and drawing when forming fibers (hereinafter simply referred to as operability), and cost. These acids may be used as they are, or ester-forming derivatives may be used. Among these, esters with ethylene glycol are preferably used in terms of operability.

[0015] The proportion of terephthalic acid in the acid component is preferably 75 to 99.5 mol%, and more preferably 85 to 99 mol%. If the proportion of terephthalic acid is less than 75 mol%, the crystallinity of the resin composition may decrease, the melting point may be lowered, and runnability may be reduced. On the other hand, if the proportion of terephthalic acid exceeds 99.5 mol%, the amount of aromatic dicarboxylic acid having a metal sulfonate group copolymerized decreases, and the effect of dyeability with cationic dyes may be reduced.

[0016] Furthermore, the acid components constituting the polyester preferably contain 2 to 18 mol % of an aliphatic dicarboxylic acid having 5 to 10 carbon atoms, when the total amount of all acid components is taken as 100 mol %. By copolymerizing an appropriate amount of an aromatic dicarboxylic acid having a metal sulfonate group and an aliphatic dicarboxylic acid having 5 to 10 carbon atoms, dyeability with cationic dyes under normal pressure conditions can be imparted to the polyester resin.

[0017] If the content (copolymerization amount) of the aliphatic dicarboxylic acid having 5 to 10 carbon atoms is less than 2 mol%, the dyeability with cationic dyes under normal pressure conditions when the copolymerized polyester is made into a fiber becomes insufficient. On the other hand, if the content of the aliphatic dicarboxylic acid component exceeds 18 mol%, the thermal stability of the copolymerized polyester decreases, and the yarn strength when made into a fiber becomes low.

[0018] Examples of the aliphatic dicarboxylic acid having 5 to 10 carbon atoms include glutaric acid, adipic acid, pimelic acid, suberic acid, and sebacic acid. In the present invention, adipic acid is preferably used from the viewpoints of operability and cost during melt spinning.

[0019] Furthermore, the polyester resin of the present invention preferably contains 8 to 15 mol% of isophthalic acid among the acid components constituting the polyester, assuming the total amount of all acid components to be 100 mol%. By containing 8 mol% or more of isophthalic acid, the resulting fiber can have high heat shrinkage. For example, when used in a side-by-side composite fiber with another polyester resin, it is possible to obtain a woven or knitted fabric that exhibits both dyeability with cationic dyes and stretchability. On the other hand, if the isophthalic acid content exceeds 15 mol%, the yarn strength tends to decrease and the operability during spinning tends to deteriorate.

[0020] In the polyester resin of the present invention, examples of acid components other than terephthalic acid, aromatic dicarboxylic acid having a metal sulfonate group, aliphatic dicarboxylic acid having 5 to 10 carbon atoms, and isophthalic acid include phthalic acid, phthalic anhydride, naphthalenedicarboxylic acid, 1,4-cyclohexanedicarboxylic acid, dodecanedioic acid, and other dimer acids, as well as trimellitic anhydride, trimellitic acid, pyromellitic acid, 1,4-cyclohexanedicarboxylic acid, and dimer acids. Two or more of these may be used in combination, and ester-forming derivatives of these acids may also be used.

[0021] The polyester resin of the present invention contains diethylene glycol and triethylene glycol, and when the total amount of all glycol components constituting the polyester is taken as 100 mol %, the triethylene glycol content is 0.5 mol % to 5.5 mol %. The triethylene glycol content is preferably 0.6 mol % to 5.0 mol %, and more preferably 0.7 mol % to 4.0 mol %. If the triethylene glycol content is less than 0.5 mol %, the operability is poor, and the dyeability effect and excellent yarn quality characteristics (strength and elongation) when made into fibers are not fully exhibited. On the other hand, if the content exceeds 5.5 mol %, the melting point is low, and the operability and heat resistance are reduced.

[0022] The total content of triethylene glycol and tetraethylene glycol in the total glycol components is preferably 7.0 mol% or less, more preferably 0.6 mol% to 4.0 mol%, and even more preferably 0.8 mol% to 3.0 mol%. If it exceeds 7.0 mol%, heat resistance may decrease, and the operability when producing fibers and the yarn quality of the fibers may be poor. On the other hand, if it is less than 0.6 mol%, the operability when producing fibers and the dyeability may be poor.

[0023] The content of tetraethylene glycol in the total glycol components is preferably 2.0 mol% or less, more preferably 1.0 mol% or less, and even more preferably 0.5 mol% or less. If it exceeds 2.0 mol%, the heat resistance and yarn quality may deteriorate.

[0024] The diethylene glycol content is preferably 2.5 mol% or more, more preferably 3.5 mol% or more, and even more preferably 4.5 mol% or more of the total glycol components. By setting the diethylene glycol content within this range, dyeability of the resulting fiber can be improved. From the viewpoints of operability and yarn quality characteristics, the upper limit of the diethylene glycol content is preferably 12 mol%.

[0025] In order to adjust the content of each of diethylene glycol, triethylene glycol, and tetraethylene glycol, for example, the content of aromatic dicarboxylic acid having a metal sulfonate group can be set within a preferred range, an organic sulfonic acid compound can be used as a polymerization catalyst in the production method of a polyester resin described below, the amount of organic sulfonic acid compound added can be set within a preferred range, the molar ratio (G / A) of glycol component (G) to acid component (A) before being subjected to the etherification reaction can be set within a preferred range, or the temperature or time of the etherification reaction can be adjusted.

[0026] The polyester resin of the present invention may contain a glycol component other than those mentioned above, such as 1,2-propylene glycol, neopentyl glycol, 1,6-hexanediol, 1,4-butanediol, 1,4-cyclohexanediol, 1,4-cyclohexanedimethanol, dimer diol, an ethylene oxide adduct of bisphenol S, or an ethylene oxide adduct of bisphenol A.

[0027] The polyester resin of the present invention preferably has an intrinsic viscosity of 0.45 dL / g or more, more preferably 0.5 dL / g or more, and even more preferably 0.6 to 0.8 dL / g. If the intrinsic viscosity is less than 0.45 dL / g, sufficient yarn quality characteristics may not be obtained.

[0028] The intrinsic viscosity in the present invention is a value measured at a temperature of 20°C using an equal weight mixture of phenol and tetrachloroethane as a solvent.

[0029] The polyester resin of the present invention may contain any polymer, antistatic agent, antifoaming agent, dyeability improver, dye, pigment, matting agent, fluorescent brightener, stabilizer, antioxidant, colorant, flame retardant, or other additives, as long as the effects of the present invention are not impaired. Examples of antioxidants include aromatic amine-based and phenol-based antioxidants. Examples of stabilizers include phosphorus-based, sulfur-based, and amine-based stabilizers such as phosphoric acid or phosphate ester-based stabilizers.

[0030] The polyester resin of the present invention may contain organic, inorganic, or organometallic toners, fluorescent brighteners, etc., to the extent that the effects of the present invention are not impaired. This can further suppress coloration, such as yellowing, of the polyester resin. Alternatively, other resins such as polyethylene, or inorganic nucleating agents such as talc may be added to improve crystallinity.

[0031] The polyester resin of the present invention may contain a cobalt compound for the purpose of improving color tone, etc., as long as the effects of the present invention are not impaired. The cobalt compound is not particularly limited, but specific examples include cobalt acetate, cobalt nitrate, cobalt chloride, cobalt acetylacetonate, cobalt naphthenate, and hydrates thereof. Cobalt acetate tetrahydrate is particularly preferred. The amount of the cobalt compound added is preferably 10 ppm or less, more preferably 5 ppm or less, and even more preferably 3 ppm or less, in terms of cobalt atoms, relative to the polyester resin.

[0032] The polyester resin of the present invention may be mixed with waste resin generated in the manufacturing process or recycled polyester resin recovered from the market (for example, PET bottles).

[0033] (Method of producing polyester resin) The method for producing a polyester resin of the present invention includes a step of adding an organic sulfonic acid compound to a polyester raw material and heating the mixture at a temperature of 240°C or higher for 5 to 120 minutes under normal pressure or pressure to carry out an etherification reaction of the glycol component.

[0034] In the present invention, by including a step of carrying out an etherification reaction under specific conditions before carrying out the polycondensation reaction, the contents of diethylene glycol and triethylene glycol can be set within specific ranges, thereby obtaining a polyester resin with excellent operability and dyeability.

[0035] Examples of raw materials for polyester resins include glycol components containing ethylene glycol as a main component, dicarboxylic acid components, and esters as low-order condensates of glycol components and dicarboxylic acid components.

[0036] For example, when producing polyethylene terephthalate as a polyester resin, the esterified product can be obtained by directly reacting terephthalic acid, ethylene glycol, and, if necessary, other copolymerization components, distilling off water, and esterifying the mixture to obtain an esterified product as a raw material for the polyester resin. Alternatively, dimethyl terephthalate, ethylene glycol, and, if necessary, other copolymerization components can be reacted, distilling off methyl alcohol, and then transesterifying the mixture to obtain an esterified product.

[0037] The method for preparing the esterified product will be described below. A slurry containing preferably 1.02 to 2.5 mol, more preferably 1.03 to 1.8 mol, of ethylene glycol per mol of dicarboxylic acid or its ester derivative is prepared, and this is continuously fed to an esterification reactor to obtain an esterified product.

[0038] The esterification reaction is carried out under reflux conditions of ethylene glycol while removing water or alcohol produced by the reaction from the system using a rectification column. The esterification reaction can be carried out using a multistage apparatus in which multiple esterification reactors are connected in series.

[0039] When the esterification reaction is carried out in multiple stages, the temperature of the first stage esterification reaction is preferably 240 to 270°C, more preferably 245 to 265°C. The pressure is 0.2 to 3 kg / cm. 2 G is preferably 0.5 to 2 kg / cm 2 G is more preferred.

[0040] The temperature of the final stage esterification reaction is preferably 250 to 290°C, more preferably 255 to 275°C. The pressure is 0 to 1.5 kg / cm. 2G is preferably 0 to 1.3 kg / cm 2 G is more preferred.

[0041] When the esterification reaction is carried out in three or more stages, the reaction conditions for the intermediate stages are preferably intermediate between the reaction conditions for the first stage and the reaction conditions for the final stage. The reaction rate of the multi-stage esterification reaction is preferably increased smoothly in each stage. The final esterification reaction rate preferably reaches 90% or more, more preferably 93% or more. These esterification reactions can produce an esterified product, the molecular weight of which is preferably about 500 to 5,000.

[0042] When terephthalic acid is used in the esterification reaction, the reaction proceeds due to the catalytic action of terephthalic acid as an acid.

[0043] To the esterified product obtained as described above, an aromatic dicarboxylic acid having a metal sulfonate group and an alkali metal compound are added, and a depolymerization reaction is carried out as necessary. Then, an organic sulfonic acid compound is added to carry out an etherification reaction. Thereafter, a polycondensation reaction is carried out to obtain the polyester resin of the present invention.

[0044] The amount of aromatic dicarboxylic acid having a metal sulfonate group added relative to the esterified product is, for example, a mass ratio of (esterified product) / (aromatic dicarboxylic acid having a metal sulfonate group)=4.0 to 30.0, which makes it easier to keep the content of aromatic dicarboxylic acid having a metal sulfonate group within the range of the present invention and to keep the contents of diethylene glycol and triethylene glycol within the specific ranges.

[0045] In the present invention, the polymerization catalyst , other than aromatic dicarboxylic acids having a metal sulfonate group By using an organic sulfonic acid compound, the contents of diethylene glycol and triethylene glycol in the resulting polyester resin can be set within a specific range. The aforementionedExamples of organic sulfonic acid compounds include benzenesulfonic acid, m- or p-benzenedisulfonic acid, 1,3,5-benzenetrisulfonic acid, o-, m-, or p-sulfobenzoic acid, benzaldehyde-o-sulfonic acid, acetophenone-p-sulfonic acid, acetophenone-3,5-disulfonic acid, o-, m-, or p-aminobenzenesulfonic acid, sulfanilic acid, 2-aminotoluene-3-sulfonic acid, phenylhydroxylamine-3-sulfonic acid, phenylhydrazine-3-sulfonic acid, 1-nitronaphthalene-3-sulfonic acid, thiophenol-4-sulfonic acid, anisole-o-sulfonic acid, 1,5-naphthalenedisulfonic acid, o-, m-, or p-chlorobenzenesulfonic acid, o-, m-, or p-bromobenzenesulfonic acid, o-, m-, or p-nitrobenzenesulfonic acid, nitrobenzene-2,4-disulfonic acid, nitrobenzene-3,5-disulfonic acid, nitrobenzene-2,5-disulfonic acid, 2-nitrotoluene-5-sulfonic acid, 2-nitrotoluene-4-sulfonic acid, 2-nitrotoluene-6-sulfonic acid, 3-nitrotoluene-5-sulfonic acid, 4-nitrotoluene-2-sulfonic acid, 3-nitro-o-xylene-4-sulfonic acid, 5-nitro-o-xylene-4-sulfonic acid, 2-nitro-m-xylene-4-sulfonic acid, 5-nitro-m-xylene-4-sulfonic acid, 3-nitro-p-xylene-2-sulfonic acid, 5-nitro-p-xylene-2-sulfonic acid, 6-nitro-p-xylene-2-sulfonic acid, 2,4-dinitrobenzenesulfonic acid, 3,5-dinitrobenzenesulfonic acid, o-, m- or p-fluorobenzenesulfonic acid, 4-chloro-3-methylbenzenesulfonic acid, 2-chloro-4-sulfobenzoic acid, 5-sulfosalicyl Acid, 2 -Sulfobenzoic anhydride, 3,4-dimethyl-2-sulfobenzoic anhydride, 4-methyl-2-sulfobenzoic anhydride, 5-methoxy-2-sulfobenzoic anhydride, 1-sulfonaphthoic anhydride, 8-sulfonaphthoic anhydride Things, MeTanesulfonic acid, ethanesulfonic acid, methionic acid, cyclopentanesulfonic acid, 1,1-ethanedisulfonic acid, 1,2-ethanedisulfonic acid, 1,2-ethanedisulfonic anhydride, 3-propanedisulfonic acid, β-sulfopropionic acid, isethionic acid, dithionic acid, dithionic anhydride, 3-oxy-1-propanesulfonic acid, 2-chloroethanesulfonic acid, phenylmethanesulfonic acid, β-phenylethanesulfonic acid, α-phenylethanesulfonic acid, ammonium chlorosulfonate, methyl benzenesulfonate, ethyl p-toluenesulfonate, ethyl methanesulfonate, 5-dimethylsulfosalicylate Lu et al. Among these, from the viewpoint of versatility, 2-sulfobenzoic anhydride, o-sulfobenzoic acid, m-sulfobenzoic acid, p-sulfobenzoic acid, 5-sulfosalicylic acid, benzenesulfonic acid, o-aminobenzenesulfonic acid, m-aminobenzenesulfonic acid, p-aminobenzenesulfonic acid, p-toluenesulfonic acid, methyl p-toluenesulfonate, and salts thereof are preferred.

[0046] When a metal catalyst is not used as the polymerization catalyst, the content of metal components derived from the metal catalyst in the resulting polyester resin of the present invention can be reduced. A high content of metal components may result in the generation of foreign matter during melt spinning. The content of metal components is preferably 1 ppm or less, more preferably 0.5 ppm or less, and even more preferably 0 ppm. Examples of metal catalysts include compounds of antimony, germanium, tin, titanium, zinc, aluminum, iron, magnesium, potassium, calcium, sodium, manganese, nickel, and cobalt.

[0047] The organic sulfonic acid compound can be added, for example, in the form of a solid, a slurry, or a solution dissolved in water, glycol, or the like.

[0048] The above-mentioned as a polymerization catalyst The amount of organic sulfonic acid compound added depends on the type, but is generally 0.5 x 10 per mole of the acid component that constitutes the polyester resin. -4~40×10 -4 The amount is preferably 1.0 to 20.0 × 10 -4 It is more preferable that the amount is less than the above range and is therefore less than 100% by weight. If the amount is too small, it may be impossible to obtain a polyester resin with a high degree of polymerization, and it may be impossible to obtain a fiber with excellent strength and dyeability. Alternatively, the contents of diethylene glycol and triethylene glycol may not fall within the specific range. On the other hand, if the amount is too large and exceeds the above range, the content of triethylene glycol may become too high, or this may cause discoloration of the polyester resin.

[0049] The above-mentioned as a polymerization catalyst By adjusting the amount of the organic sulfonic acid compound to be added within the above range, the content of sulfur components other than the aromatic dicarboxylic acid having a metal sulfonate group (i.e., sulfur components derived from the catalyst) in the resulting polyester resin can be reduced. 5 ~100 ppm and The sulfur content is preferably 6 to 60 ppm. If the sulfur content is less than 5 ppm, the yarn quality may be poor when made into fibers. On the other hand, if the sulfur content exceeds 100 ppm, it may cause discoloration of the polyester.

[0050] The temperature of the etherification reaction is preferably 240°C or higher, more preferably 240 to 300°C, and even more preferably 250 to 280°C. If the temperature is lower than 240°C, the reaction may not proceed sufficiently, and the contents of diethylene glycol and triethylene glycol may not be within the specified range. If the temperature exceeds 300°C, decomposition of the esterified product may proceed during the reaction, which may result in a decrease in operability when producing fibers and in the yarn quality characteristics of the fibers.

[0051] The etherification reaction time is preferably 5 to 120 minutes, more preferably 10 to 60 minutes. If the reaction time is less than 5 minutes, the reaction may not proceed sufficiently, and the diethylene glycol and triethylene glycol contents may not fall within the specified range. If the reaction time exceeds 120 minutes, the etherification reaction may proceed too far, and the diethylene glycol and triethylene glycol contents may not fall within the specified range, or decomposition of the esterified product may proceed during the reaction, which may result in a decrease in operability when producing fibers and in the yarn quality characteristics of the fibers.

[0052] The etherification reaction is preferably carried out under normal pressure or pressure, and the pressure is 0 to 3.0 kg / cm. 2 Preferably it is G.

[0053] The content of diethylene glycol and triethylene glycol can be set within a specific range by adjusting the ratio (G / A) of glycol components to acid components in the raw materials used in the etherification reaction. G / A is preferably 1.05 to 3.00, and more preferably 1.10 to 2.00. To adjust G / A, a glycol component such as ethylene glycol may be added to the polyester raw material as needed. If it is less than 1.05, the amount of triethylene glycol produced tends to be small, whereas if it exceeds 3.00, the amount of triethylene glycol produced tends to be large.

[0054] After the etherification reaction, a polycondensation reaction can be carried out to obtain the polyester resin of the present invention. Examples of the polycondensation reaction include a melt polycondensation reaction. The polycondensation reaction may be carried out in one stage or in multiple stages.

[0055] The polycondensation reaction conditions are not particularly limited, but the temperature of the first stage polycondensation reaction is preferably 250 to 290° C., more preferably 260 to 280° C. The pressure is preferably 500 to 20 hPa, more preferably 200 to 30 hPa.

[0056] In the case of a multi-stage process, the temperature of the polycondensation reaction in the final stage is preferably 265 to 300°C, and more preferably 275 to 295°C. The pressure is preferably 10 to 0.1 hPa, and more preferably 5 to 0.5 hPa. When the process is carried out in three or more stages, the reaction conditions in the intermediate stages are preferably between those in the first stage and the final stage. It is preferable to smoothly increase the degree of polymerization in each of these stages.

[0057] Furthermore, during the polycondensation reaction, if necessary, a hindered phenol-based antioxidant, a phosphorus compound capable of suppressing thermal decomposition of the resin, and titanium oxide for improving whiteness can also be added together with the above-mentioned polymerization catalyst.

[0058] Examples of hindered phenol antioxidants include 2,6-di-t-butyl-4-methylphenol, n-octadecyl-3-(3',5'-di-t-butyl-4'-hydroxyphenyl)propionate, tetrakis[methylene-3-(3,5-di-t-butyl-4-hydroxyphenyl)propionate]methane, tris(3,5-di-t-butyl-4-hydroxybenzyl)isocyanurate, 4,4'-butylidenebis-(3-methyl-6-t-butylphenol), ... Examples of suitable compounds include ethylene glycol-bis[3-(3-t-butyl-4-hydroxy-5-methylphenyl)propionate] and 3,9-bis{2-[3-(3-t-butyl-4-hydroxy-5-methylphenyl)propionyloxy]-1,1'-dimethylethyl}-2,4,8,10-tetraoxaspiro[5,5]undecane, but tetrakis[methylene-3-(3,5-di-t-butyl-4-hydroxyphenyl)propionate]methane is preferred from the standpoint of effectiveness and cost. These compounds can be used alone or in combination of two or more.

[0059] Examples of phosphorus compounds that can be used include phosphorous acid, phosphoric acid, trimethyl phosphite, triphenyl phosphite, tridecyl phosphite, trimethyl phosphate, triethyl phosphate, tridecyl phosphate, and triphenyl phosphate. These compounds can be used alone or in combination of two or more.

[0060] Titanium oxide is commonly used as a matting agent or white pigment for polyester, and adding an appropriate amount of titanium oxide to the polyester resin of the present invention is preferable because it improves the whiteness of the fibers when made into fibers and enables the production of woven or knitted fabrics with good color tone. The amount of titanium oxide added is preferably 0.05 to 5 parts by mass per 100 parts by mass of the polyester resin.

[0061] (Uses of polyester resin) The polyester resin of the present invention can be used in a variety of applications, particularly in fiber applications, but can also be used in molded products such as sheets, films, and injection molded articles.

[0062] The fiber of the present invention is made from the polyester resin of the present invention. The fiber of the present invention can be obtained, for example, by spinning the polyester resin of the present invention. The spinning method can be carried out under known conditions. The fiber of the present invention may be, for example, an ultrafine fiber having a single fiber fineness of 0.8 dtex or less (preferably 0.6 to 0.3 dtex).

[0063] The fibers of the present invention may be, for example, monofilaments, multifilaments, or the like, and may be either long fibers or short fibers. The shape of the single fibers constituting the fiber of the present invention is not particularly limited, and they may have not only a round cross section but also an irregular cross section such as a polygonal cross section.

[0064] The fiber of the present invention may be not only a fiber in which all of the single fibers are formed from the polyester resin of the present invention, but also a conjugated fiber in which the polyester resin of the present invention is conjugated with other polyester resins (such as virgin polyester resins or polyester resins containing other copolymer components). Examples of the form of the conjugated fiber include a core-sheath type, a side-by-side type, and an islands-in-sea type.

[0065] The proportion of the polyester resin of the present invention contained in the fiber of the present invention is preferably 30% by mass or more, more preferably 50% by mass or more, and even more preferably 70% by mass or more, and when the fiber of the present invention is not a composite fiber, it is preferably 80% by mass or more, more preferably 90% by mass or more, and even more preferably 100% by mass.

[0066] When the fiber of the present invention is a multifilament, its characteristic values ​​may include, for example, a single yarn fineness of 0.3 to 30 decitex, a single yarn count of 2 to 300, a total fineness of 5 to 350, a strength of 1 to 5 cN / decitex, and an elongation of 10 to 400%.

[0067] The fiber of the present invention can be dyed with a cationic dye, and when dyed, it exhibits excellent dyeability without causing color spots or color differences.Furthermore, it also exhibits excellent yarn quality properties such as strength. [Example]

[0068] The present invention will be specifically described below based on examples, but the present invention is not limited to these. Measurements and evaluations were carried out by the following methods.

[0069] (1) Intrinsic viscosity [η] The measurement was carried out at 20°C using an equal weight mixture of phenol and tetrachloroethane as a solvent.

[0070] (2) Composition of polyester resin 10 mg of sample was dissolved in 1 mL of a mixed solvent of deuterated chloroform / deuterated trifluoroacetic acid = 9 / 1 (mass ratio), and the sample was analyzed using a JEOL LA-400 NMR spectrometer. 1 H-NMR was measured, and the total amount of the dicarboxylic acid component, triethylene glycol component, and tetraethylene glycol component, as well as the molar ratio of each of the other glycol components, were calculated from the integrated proton peak intensity of each component in the obtained chart. Next, the amounts of triethylene glycol and tetraethylene glycol were determined as follows. The polyester resin was hydrolyzed in a 0.75N potassium hydroxide / methanol solution, and then neutralized by adding terephthalic acid. The filtrate was then measured by gas chromatography, and the molar ratio of triethylene glycol to tetraethylene glycol was calculated using a calibration curve prepared in advance. 1 The contents of triethylene glycol and tetraethylene glycol in all glycol components were calculated from the results of H-NMR measurement (the molar ratio between the total amount of triethylene glycol and tetraethylene glycol and each of the other glycol components).

[0071] (3) Melting point (Tm), glass transition temperature (Tg) The measurements were carried out using a PerkinElmer DSC-7 differential scanning calorimeter in a nitrogen stream at a temperature range of 25 to 280°C and a heating rate of 20°C / min.

[0072] (4) Content of sulfur components derived from catalyst The polyester resin was melt-molded at 300°C to form a disk-shaped molded plate with a diameter of 3 cm and a thickness of 1 cm, and quantitative analysis of the sulfur component was performed using a Rigaku ZSX Primus X-ray fluorescence analyzer by the calibration curve method. Next, 10 mg of the sample was dissolved in 1 mL of a mixed solvent of deuterated chloroform / deuterated trifluoroacetic acid = 9 / 1 (mass ratio), and the sample was analyzed using a JEOL LA-400 NMR spectrometer. 1H-NMR was measured, and the molar ratio of 5-Na sulfoisophthalic acid diglycol ester (SIPG) was calculated from the integrated proton peak intensity of each component in the obtained chart, and the sulfur content derived from SIPG was calculated from that. The amount of sulfur components derived from the catalyst was calculated by subtracting the amount of sulfur derived from SIPG calculated by NMR from the amount of sulfur components quantitatively analyzed by an X-ray fluorescence analyzer.

[0073] The evaluation methods for fibers (operability, dyeability, strength, elongation, stretchability) are as follows: (5) Fiber runnability (broken yarn during spinning) A case where the number of times the yarn was broken during 24 hours of continuous melt spinning was 3 times / (day / spindle) or less was marked as "○", and other cases were marked as "×". (6) Fiber runnability (breakage during drawing) The number of times that thread breakage occurred during 12 consecutive hours of drawing was counted, and the rate of thread breakage (%) was calculated and evaluated using the following formula. Breakage rate (%) = {(total number of spindles drawn) - (number of spindles that could be drawn without breaking threads for 12 hours)} ÷ (total number of spindles drawn) × 100 ○: Breakage rate during stretching ≦5% ×: Breakage rate during stretching > 5%

[0074] (7) Thread quality According to JIS L-1013, strength and elongation were measured using an autograph DSS-500 manufactured by Shimadzu Corporation at a gripping distance of 50 cm and a pulling speed of 50 cm / min. In the present invention, the strength is preferably 2.0 cN / dtex or more, more preferably 3.0 cN / dtex or more. The elongation is preferably 28% or more, more preferably 30% or more. When both the strength and elongation are within the above ranges, this is an indicator of an excellent balance of yarn quality characteristics.

[0075] (8) Stainability The obtained multifilament was knitted into a cylindrical knitted fabric using a knitting machine (manufactured by Koike Machinery Works, number of needles: 300, diameter of kettle: 3.5 inches). The produced cylindrical knitted fabric was dyed at 130°C for 30 minutes under conditions of 0.5% owf using Astorazon Blue FRR as the dye and a dye solution containing acetic acid, sodium acetate, and Ionet as auxiliaries. Thirty dyed cylindrical knitted fabrics were visually observed and evaluated for the presence or absence of dye streaks or dye spots. The number of good products with neither dye streaks nor dye spots was counted and rated as follows: 〇: 27 or more good quality items ×: The number of good products is 26 or less

[0076] (9) Normal pressure dyeability (L value after dyeing) The obtained multifilament yarn was knitted into a cylindrical knitted fabric using a knitting machine (manufactured by Koike Kikai Seisakusho, number of needles: 300, diameter of kettle: 3.5 inches). The resulting cylindrical knit fabric was scoured at 60°C for 20 minutes, then dyed at 100°C for 60 minutes under normal pressure under the dyeing conditions described below and air-dried. Next, a small pin tenter was used to heat-set the fabric at 150°C for 1 minute, after which a four-ply sample piece was prepared. The L value of this sample piece was measured using a color difference meter to evaluate its dyeability. The lower the L value, the darker the color of the fiber, and the better the dyeability. An L value of 35 or less was considered acceptable. The 30 dyed cylindrical knitted fabrics were visually inspected for the presence or absence of dye streaks or dye spots, and the number of non-defective fabrics having neither dye streaks nor dye spots was counted and evaluated as follows: 〇: 27 or more good quality items ×: The number of good products is 26 or less (Dyeing conditions) Dye: Astrazon Blue 0.5% omf Leveling agent: acetic acid 0.2mL / L Sodium acetate 0.2g / L Bath ratio: 1:50 (10) Stretchability The samples (tubular knit fabrics) used for dyeability evaluation were subjected to a sensory evaluation by 10 panelists. Evaluation was made on a scale of 1 to 10, with the highest stretchability being given a perfect score of 10, and the average score of the 10 panelists was expressed. A score of 7 or more was marked as ○, and a score of less than 7 was marked as ×.

[0077] [Preparation of esterified products] A slurry of terephthalic acid and ethylene glycol (molar ratio 1 / 1.6) was continuously supplied to an esterification reactor and reacted at a temperature of 250°C and a pressure of 0.2 MPa for a residence time of 8 hours to obtain an esterified product (terephthalic acid:ethylene glycol = 100:111 (molar ratio)).

[0078] Example 1 [Polyester resin] The heated and melted esterified product and 5-Na sulfoisophthalic acid diglycol ester (SIPG) as a polymerization catalyst were charged into a polycondensation reactor heated to 280°C, and 2.0 × 10 5-sulfosalicylic acid dihydrate (SS) was added. -4 The reaction mixture was added in an amount of 1000 mol / mol of acid component, and the etherification reaction was carried out at 260°C under atmospheric pressure for 10 minutes. Next, while maintaining the reactor temperature at 280°C, the system pressure was gradually reduced to 0.5 hPa or less after 60 minutes. Under these conditions, the polycondensation reaction was carried out with stirring for 3 hours to obtain a polyester resin. The polyester resin contained 25 ppm of catalyst-derived sulfur components and a triethylene glycol content of 1.1 mol%.

[0079] [Production of Long Fibers] The resulting polyester resin was dried and then spun at a spinning temperature of 303°C using a spinneret with 84 nozzles, followed by cooling and oil application while winding at a speed of 2900 m / min to obtain a partially oriented yarn. This was then drawn under conditions of a roll heater temperature of 90°C, a plate heater of 150°C, and a drawing speed of 600 m / min, and then wound up to obtain a 45 dtex / 84 filament multifilament yarn (drawn yarn).

[0080] Examples 2 to 6, Comparative Examples 1 to 7 [Polyester resin] As shown in Table 1, the same operation as in Example 1 was carried out, except that the amount of 5-Na sulfoisophthalic acid diglycol ester (SIPG), the amount of 5-sulfosalicylic acid dihydrate (SS), and the etherification conditions were changed, to obtain a polyester resin. Then, a multifilament yarn was obtained in the same manner as in Example 1.

[0081] Comparative Example 8 A polyester resin was obtained in the same manner as in Example 1, except that antimony trioxide (Sb) was used instead of 5-sulfosalicylic acid dihydrate (SS). Then, a multifilament yarn was obtained in the same manner as in Example 1.

[0082] Example 7 A polyester resin was obtained by the same procedure as in Example 1, except that 2.1 parts by mass of isophthalic acid (IPA) was added to the polycondensation reactor. The resulting polyester resin and the polyester resin obtained in Example 3 were used as the other polyester resin. After drying, these resins were fed in equal masses into a conjugate spinning melt extruder, melted at a spinning temperature of 290°C, and spun side-by-side into a spinneret with 12 nozzles. The spun yarn was cooled and solidified, then wound at a speed of 3,000 m / min while applying an oil, to obtain an undrawn yarn. The undrawn yarn was then heat-treated with a roller at 85°C, stretched at a draw ratio of 1.7, and simultaneously heat-treated at 185°C (heat plate temperature) to obtain a 56 dtex / 12 filament conjugate multifilament yarn.

[0083] Examples 8 and 9 A polyester resin was obtained in the same manner as in Example 7, except that the amount of isophthalic acid (IPA) added was changed. Then, a multifilament yarn was obtained in the same manner as in Example 7.

[0084] Example 10 A polyester resin was obtained in the same manner as in Example 1, except that 1.8 parts by mass of adipic acid (AD) was added to the polycondensation reactor. A multifilament yarn was then obtained in the same manner as in Example 1.

[0085] Examples 11 and 12 A polyester resin was obtained in the same manner as in Example 10, except that the amount of adipic acid (AD) added was changed. Then, a multifilament yarn was obtained in the same manner as in Example 1.

[0086] Table 1 shows the raw material composition of the polyester resins, the production conditions, and the compositions of the resulting polyester resins in the examples and comparative examples.

[0087] [Table 1]

[0088] Table 2 shows the properties of the polyester resins and fibers obtained in the examples and comparative examples.

[0089] [Table 2]

[0090] As shown in Table 2, the polyester resins obtained in Examples 1 to 12 had diethylene glycol and triethylene glycol contents within the ranges specified in the present invention, and therefore had excellent dyeability with cationic dyes and fibers with excellent yarn quality characteristics (strength, elongation) could be obtained with good operability. Among them, the conjugated fibers using the polyester resins obtained in Examples 7 to 9 also had excellent stretchability. The fibers made of the polyester resins obtained in Examples 10 to 12 also had excellent normal pressure dyeability.

[0091] On the other hand, in Comparative Example 1, the content of the aromatic dicarboxylic acid having a metal sulfonate group was high, and therefore the content of triethylene glycol in the polyester resin was high, resulting in an amorphous resin with poor heat resistance, poor spinning operability, and poor dyeing quality.

[0092] In Comparative Example 2, the content of the aromatic dicarboxylic acid having a metal sulfonate group was low, and therefore the content of triethylene glycol in the polyester resin was low, resulting in a resin with a high melting point and poor operability during stretching.

[0093] In Comparative Example 3, the etherification reaction was not carried out, so the content of triethylene glycol in the polyester resin was low, and as a result, the operability in stretching was poor.

[0094] In Comparative Example 4, the amount of 5-sulfosalicylic acid dihydrate added as a polymerization catalyst was large, which resulted in a high content of triethylene glycol in the polyester resin, resulting in an amorphous resin with low heat resistance. The spinning operability was poor, and the dyeing quality was also poor.

[0095] In Comparative Example 5, the amount of 5-sulfosalicylic acid dihydrate added as a polymerization catalyst was small, resulting in a low content of triethylene glycol, which resulted in poor operability in stretching.

[0096] In Comparative Example 6, the temperature of the etherification reaction was lowered, resulting in a lower content of triethylene glycol in the polyester resin, which resulted in poor operability in stretching.

[0097] In Comparative Example 7, the etherification reaction time was extended, resulting in a high content of triethylene glycol in the polyester resin. As a result, the resin was amorphous and had low heat resistance. The spinning operability was poor, and the dyeing quality was also poor.

[0098] In Comparative Example 8, antimony trioxide was added as a polymerization catalyst instead of 5-sulfosalicylic acid dihydrate (SS), resulting in a reduced content of triethylene glycol in the polyester resin, which resulted in poor operability during stretching.

Claims

1. A polyester resin comprising a dicarboxylic acid component and a glycol component, wherein the dicarboxylic acid component contains terephthalic acid as a main component and also contains an aromatic dicarboxylic acid having a metal sulfonate group; the glycol component contains ethylene glycol as a main component and also contains diethylene glycol and triethylene glycol, the content of triethylene glycol in the glycol component being 0.5 mol % or more and 5.5 mol % or less; and the content of sulfur components other than the aromatic dicarboxylic acid having a metal sulfonate group is 5 to 100 ppm.

2. 2. The polyester resin according to claim 1, wherein the glycol component contains diethylene glycol in an amount of 2.5 mol% or more.

3. 3. The polyester resin according to claim 1, wherein the glycol component contains tetraethylene glycol, and the content of tetraethylene glycol in the glycol component is 2.0 mol% or less.

4. 4. The polyester resin according to claim 3, wherein the total content of triethylene glycol and tetraethylene glycol in the glycol component is 7.0 mol% or less.

5. 5. The polyester resin according to claim 1, wherein the content of the aromatic dicarboxylic acid having a metal sulfonate group in the dicarboxylic acid component is 0.5 to 5.5 mol %.

6. 6. The polyester resin according to claim 1, wherein the dicarboxylic acid component comprises an aliphatic dicarboxylic acid having 5 to 10 carbon atoms, and the content of the aliphatic dicarboxylic acid in the dicarboxylic acid component is 2 to 18 mol%.

7. The polyester resin according to any one of claims 1 to 6, wherein the dicarboxylic acid component contains isophthalic acid in an amount of 8 to 15 mol%.

8. A fiber made of the polyester resin according to any one of claims 1 to 7.

9. A method for producing the polyester resin according to any one of claims 1 to 7, comprising the steps of adding an organic sulfonic acid compound other than an aromatic dicarboxylic acid having a metal sulfonate group to a polyester raw material, and heating the resulting mixture at a temperature of 240°C or higher for 5 to 120 minutes under normal pressure or pressure to carry out an etherification reaction of the glycol component.

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