JP2023034956A - Polyester resin and method for producing the same - Google Patents

Abstract

To provide a polyester resin from which a fiber that is excellent in dyeability to a cationic dye and is also excellent in yarn quality characteristics (strength and elongation) can be obtained with good operability.SOLUTION: A polyester resin contains a dicarboxylic acid component and a glycol component. The dicarboxylic acid component contains a terephthalic acid as a main component and contains an aromatic dicarboxylic acid having a metal sulfonate group, the glycol component contains ethylene glycol as a main component, and in DSC, a crystallization calorific value is 20 J/g or less and melting endotherm is 5 J/g or more.SELECTED DRAWING: None

Description

The present invention relates to polyester resins, fibers and processes for producing polyester resins.

Polyester resins represented by polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polyethylene naphthalate (PEN), etc. have excellent mechanical and chemical properties and are used in a wide range of fields (for example, clothing and industrial applications). fibers for materials, films or sheets for packaging and magnetic tape, bottles that are hollow molded products, casings for electrical and electronic parts, and other engineering plastic molded products).

Conventionally, an antimony-based metal-based catalyst is known as a polycondensation catalyst used in the polycondensation of polyester resins. Antimony-based catalysts are inexpensive and have excellent catalytic activity. problems or cause surface imperfections in the workpiece.

Therefore, copolyesters suitable for polyester fibers with excellent cationic dyeability, which are produced without using antimony-based catalysts as polycondensation catalysts, have been investigated (for example, Patent Document 1).

JP 2006-63215 A

In Patent Literature 1, a metal-based catalyst such as magnesium is used, but there are still problems such as deterioration of operability due to deposition of metal during polymerization or poor color tone. Therefore, polyester resins using organic catalysts are also being investigated.
In recent years, from the viewpoint of environmental friendliness, organic catalysts have been used to produce polyester resins that are excellent in dyeability with cationic dyes and that are excellent in both strength and elongation properties. is desired.

SUMMARY OF THE INVENTION An object of the present invention is to provide a polyester resin which uses an organic catalyst and which is excellent in dyeability with cationic dyes and which can yield polyester fibers having excellent strength and elongation properties.

As a result of intensive studies to solve the above problems, the present inventors have found that the dicarboxylic acid component contains an aromatic dicarboxylic acid having a metal sulfonate group, has a low metal content derived from a metal catalyst, and has a specific range. The inventors have found that the polyester fiber obtained by using a polyester resin having crystallinity has excellent dyeability with cationic dyes, and has excellent properties such as strength and elongation when made into a fiber, and arrived at the present invention. .

That is, the gist of the present invention is as follows (1) to (5).
(1) When the total amount of acid components is 100 mol%, it contains 70 mol% or more of terephthalic acid, 0.5 to 6.0 mol% of an aromatic dicarboxylic acid having a metal sulfonate group, and the total amount of glycol components. is 100 mol%, a polyester resin containing 85 mol% or more of ethylene glycol and 3 to 15 mol% of a glycol component other than ethylene glycol, when measured by DSC at a cooling rate of 20 ° C./min. A polyester resin characterized by having a melting heat value of 20 J/g or less and a melting endotherm value of 5 J/g or more when measured at a heating rate of 20°C/min.
(2) The polyester resin according to (1), wherein the acid component further contains 2 to 18 mol% of an aliphatic dicarboxylic acid having 5 to 10 carbon atoms when the total amount of the acid component is 100 mol%.
(3) The polyester resin according to (1), which further contains 5 to 16 mol % of isophthalic acid when the total amount of the acid components is 100 mol %.
(4) A fiber containing the polyester resin according to any one of (1) to (3).
(5) A method for producing a polyester resin according to any one of (1) to (3), wherein an organic sulfonic acid compound is added to the polyester raw material, and the total glycol component/total acid component is Adjusting the molar ratio to 1.05 to 2.00, heating at a temperature of 240 ° C. or higher for 5 to 120 minutes at normal pressure or under pressure to etherify the glycol component. A method for producing a polyester resin.

The polyester resin of the present invention uses an organic sulfonic acid-based compound as a catalyst and has moderate crystallinity, so that it has excellent dyeability with cationic dyes and is excellent in both strength and elongation. can get well. Further, according to the polyester resin of the present invention, it is possible to obtain a polyester fiber having a small single filament fineness and a polyester fiber having an irregular cross section with good workability.

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 contains terephthalic acid as a main component, and further contains an aromatic dicarboxylic acid having a metal sulfonate group. That is, terephthalic acid is used as the main acid component, and an aromatic dicarboxylic acid having a metal sulfonate group is used as a copolymer component. By copolymerizing an aromatic dicarboxylic acid having a metal sulfonate group, the polyester resin can be imparted with cationic dyeability.

When the total amount of all acid components constituting the polyester is 100 mol %, the content of the aromatic dicarboxylic acid having a metal sulfonate group is 0.5 to 6.0 mol %, and 0.8 to 5.0 mol %. 0 mol % is preferred.
When the content of the aromatic dicarboxylic acid having a metal sulfonate group is less than 0.5 mol%, the number of dyeing sites for the cationic dye in the entire polymer (the number of reactive groups that react with the cationic dye) is not sufficient. When the polyester resin is used to make fibers, there are cases where sufficient dyeability cannot be obtained.
On the other hand, when the content exceeds 6.0 mol %, the melt viscosity of the polyester tends to be too high in the polycondensation step, and it may be difficult to sufficiently increase the degree of polymerization. As a result, the strength of the material (for example, yarn strength when made into fibers) may decrease.

In addition, the aromatic dicarboxylic acid having a metal sulfonate group acts as a catalyst in the etherification step in the method for producing the polyester resin of the present invention, which will be described later. Therefore, by setting the content in the above range, it becomes easier to control the crystallinity of the obtained polyester resin, and the crystallinity in the specific range described later (crystallization when measured at a cooling rate of 20 ° C./min in DSC calorific value of 20 J/g or less and melting calorific value of 5 J/g or more when measured at a heating rate of 20°C/min).

Aromatic dicarboxylic acids having a metal sulfonate group include, for example, 5-sodium sulfoisophthalic acid, 5-potassium sulfoisophthalic acid, 5-lithium sulfoisophthalic acid, sodium sulfonaphthalenedicarboxylic acid, sodium sulfophenyldicarboxylic acid, 5-sodium Sulfoterephthalic acid and the like may be mentioned, but in the present invention, 5-sodium sulfoisophthalic acid is preferably used from the viewpoints of color development by cationic dyes, workability in melt spinning, and cost. These acids may be used as they are, but ester-forming derivatives may also be used. Among them, esters with ethylene glycol are preferably used from the viewpoint of workability.

The proportion of terephthalic acid in the acid component is 70 mol % or more, preferably 80 to 99.5 mol %. If the proportion of terephthalic acid is less than 70 mol %, the crystallinity of the resin composition is lowered, the melting point is lowered, and the workability in melt spinning and drawing may be lowered. On the other hand, when the proportion of terephthalic acid exceeds 99.5 mol %, the copolymerization amount of the aromatic dicarboxylic acid having a metal sulfonate group decreases, so the effect of dyeability with cationic dyes may decrease.

Furthermore, the acid component constituting the polyester preferably contains 2 to 18 mol % of an aliphatic dicarboxylic acid having 5 to 10 carbon atoms when the total amount of all acid components is 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, the polyester resin can be imparted with cationic dyeability under normal pressure conditions.

When the content (copolymerization amount) of the aliphatic dicarboxylic acid having 5 to 10 carbon atoms is less than 2 mol%, the copolyester fiber has poor dyeability with cationic dyes under normal pressure conditions. be enough. On the other hand, if the content of the aliphatic dicarboxylic acid component exceeds 18 mol %, the thermal stability of the copolyester is lowered, resulting in low fiber strength.

Examples of aliphatic dicarboxylic acids having 5 to 10 carbon atoms include glutaric acid, adipic acid, pimelic acid, suberic acid, and sebacic acid. Acids are preferably used.

Further, the polyester resin of the present invention preferably contains 5 to 16 mol % of isophthalic acid in the acid component constituting the polyester, when the total amount of all acid components is 100 mol %. By containing 5 mol% or more of isophthalic acid, it is possible to make the fiber highly heat-shrinkable. It is possible to obtain a woven or knitted fabric having On the other hand, when the content of isophthalic acid exceeds 16 mol %, the strength of the yarn tends to decrease and the workability during spinning tends to deteriorate.

Acid components other than terephthalic acid, aromatic dicarboxylic acids having a metal sulfonate group, aliphatic dicarboxylic acids having 5 to 10 carbon atoms, and isophthalic acid in the polyester resin of the present invention include phthalic acid, phthalic anhydride, and naphthalenedicarboxylic acid. , 1,4-cyclohexanedicarboxylic acid, dodecanedioic acid, etc., dimer acid, trimellitic anhydride, trimellitic acid, pyromellitic acid, 1,4-cyclohexanedicarboxylic acid, dimer acid, etc., and these are 2 More than one kind may be used in combination, and ester-forming derivatives of these acids may also be used.

The polyester resin of the present invention has an ethylene glycol content of 85 mol % or more when the total amount of all glycol components is 100 mol %. When the proportion of ethylene glycol is less than 85 mol %, the crystallinity of the resin composition is lowered, the melting point is lowered, and the workability in melt spinning and drawing may be lowered.

The polyester resin of the present invention contains 3 to 15 mol % of glycol components other than ethylene glycol when the total amount of all glycol components is 100 mol %. Specifically, it preferably contains at least one glycol component of diethylene glycol, triethylene glycol and tetraethylene glycol. When the total content of these glycol components exceeds 15 mol %, the melting point becomes low, and the workability and heat resistance when made into fibers deteriorate. On the other hand, if it is less than 3 mol %, the crystallization heat value exceeds 20 J/g when measured by DSC at a cooling rate of 20° C./min, and the dyeability of the fiber may be poor.

In order to adjust the content of the glycol component, for example, the content of the aromatic dicarboxylic acid having a metal sulfonate group is set within a preferable range, or an organic sulfonic acid compound is used as a polymerization catalyst in the method for producing a polyester resin described below. Alternatively, the amount of the organic sulfonic acid compound to be added is set within a preferable range, or the molar ratio (G/A) between the glycol component (G) and the acid component (A) before being subjected to the etherification reaction is set within a preferable range. , a method of adjusting the temperature or time in the etherification reaction can be adopted.

The polyester resin of the present invention may contain glycol components other than those mentioned above. Specific examples include 1,2-propylene glycol, neopentyl glycol, 1,6-hexanediol, 1,4-butanediol, 1,4-cyclohexanediol, 1,4-cyclohexanedimethanol, dimer diol, and bisphenol. An ethylene oxide adduct of S, an ethylene oxide adduct of bisphenol A, and the like can be used.

The polyester resin of the present invention has a crystallization exotherm of 20 J/g or less when measured by DSC at a temperature decrease rate of 20°C/min, and a melting endotherm of 5 J/min when measured at a temperature increase rate of 20°C/min. g or more. The heat value of crystallization measured by DSC at a cooling rate of 20° C./min is preferably 18 J/g or less, more preferably 1 to 12 J/g. The melting endotherm when measured at a heating rate of 20° C./min is preferably 7 J/g or more, more preferably 10 to 25 J/g.
Since the polyester resin of the present invention has such crystallinity, the melt tension during spinning is lowered and the workability is improved. Therefore, even polyester fibers with complicated cross-sectional shapes such as ultrafine fibers and multi-leaf cross-sections can be obtained with good workability. In addition, the obtained polyester fiber has good dyeability.

When the heat of crystallization exceeds 20 J/g, the crystallinity of the polyester resin is too high, so that the workability deteriorates when obtaining ultrafine fibers or polyester fibers with a complicated cross-sectional shape, and the dyeability of the fibers is inferior, which is preferable. do not have. On the other hand, if the melting endotherm is less than 5 J/g, the melting point of the polyester resin becomes too low, and the workability and heat resistance when made into fibers are lowered, which is not preferable.
In addition, in order to obtain the polyester resin of the present invention having crystallinity within the above range, it is possible by adopting the composition of the polyester resin of the present invention described above and adopting the production method of the present invention described below.

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, still more preferably 0.6 to 0.8 dl/g. If the intrinsic viscosity is less than 0.45 dl/g, the resulting fiber may not have sufficient filament properties.

In addition, 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 ethane tetrachloride as a solvent.

The polyester resin of the present invention can be any polymer, antistatic agent, antifoaming agent, dyeability improver, dye, pigment, matting agent, fluorescent brightening agent, stabilizer, as long as the effects of the present invention are not impaired. , antioxidants, colorants, flame retardants, and other additives may be added. Examples of antioxidants include aromatic amine-based and phenol-based antioxidants. Examples of stabilizers include phosphorus-based stabilizers such as phosphoric acid or phosphate-based stabilizers, sulfur-based stabilizers, and amine-based stabilizers.

The polyester resin of the present invention may contain an organic, inorganic, or organometallic toner, or a fluorescent brightening agent, etc., as long as the effects of the present invention are not impaired. Thereby, coloring such as yellowing of the polyester resin can be further suppressed. Alternatively, other resins such as polyethylene or inorganic nucleating agents such as talc may be added to improve crystallinity.

A cobalt compound may be added to the polyester resin of the present invention for the purpose of improving the 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 thereof include cobalt acetate, cobalt nitrate, cobalt chloride, cobalt acetylacetonate, cobalt naphthenate, and hydrates thereof. Among them, 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 still more preferably 3 ppm or less, relative to the polyester resin in terms of cobalt atoms.

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

(Method for producing polyester resin)
In the method for producing the polyester resin of the present invention, an organic sulfonic acid compound is added to the polyester raw material, and the molar ratio of all glycol components / all acid components is adjusted to 1.05 to 2.00. It includes a step of heating at a temperature of 240° C. or higher for 5 to 120 minutes under pressure or pressure to etherify the glycol component.

In the present invention, the content of diethylene glycol and triethylene glycol can be set within a specific range by including a step of performing an etherification reaction under specific conditions before performing a polycondensation reaction. As a result, it is possible to obtain a polyester resin that is excellent in workability when made into fibers and also excellent in dyeability when made into fibers.

Raw materials for the polyester resin include, for example, a glycol component containing ethylene glycol as a main component, a dicarboxylic acid component, and an esterified product as a low-order condensate composed of a glycol component and a dicarboxylic acid component.

As a method for obtaining the esterified product, for example, when producing polyethylene terephthalate as a polyester resin, terephthalic acid, ethylene glycol, and if necessary, other copolymer components are directly reacted to distill off water to obtain an ester. to obtain an esterified product as a raw material for a polyester resin. Alternatively, dimethyl terephthalate, ethylene glycol and, if necessary, other copolymer components are reacted to distill off the methyl alcohol and transesterify to obtain an esterified product.

The method for preparing the esterified product will be described below.
Dicarboxylic acid or a slurry containing preferably 1.02 to 2.5 mol, more preferably 1.03 to 1.8 mol of ethylene glycol per 1 mol of an ester derivative thereof is prepared and esterified. It is continuously supplied to the reactor to obtain an esterified product.

The esterification reaction is carried out under the condition that ethylene glycol is refluxed while removing water or alcohol produced by the reaction out of the system in a rectifying column. The esterification reaction can be carried out using a multi-stage apparatus in which multiple esterification reactors are connected in series.

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

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

When the reaction is carried out in three or more stages, the reaction conditions for the esterification reaction in the intermediate stage are preferably between the reaction conditions in the first stage and the reaction conditions in the final stage.
It is preferable that the reaction rate of the multistage esterification reaction be smoothly increased in each stage. The final esterification reaction rate preferably reaches 90% or more, more preferably 93% or more. Esterified products can be obtained by these esterification reactions, and the preferred molecular weight thereof is about 500 to 5,000.

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

An aromatic dicarboxylic acid having a metal sulfonate group and an alkali metal compound are added to the esterified product obtained as described above, and an organic sulfonic acid compound is added to carry out an etherification reaction. Thereafter, the polycondensation reaction is allowed to proceed to obtain the polyester resin of the present invention.

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

In the present invention, by using an organic sulfonic acid-based compound as a polymerization catalyst, the contents of diethylene glycol and triethylene glycol in the resulting polyester resin can be set within specific ranges. Examples 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- Sulfosalicylic acid, 4-sulfophthalic acid, 2-sulfobenzoic anhydride, 3,4-dimethyl-2-sulfobenzoic anhydride, 4-methyl-2-sulfobenzoic anhydride, 5-methoxy-2-sulfobenzoic anhydride Acid anhydride, 1-sulfonaphthoic anhydride, 8-sulfonaphthoic anhydride, 3,6-disulfophthalic anhydride, 4,6-disulfoisophthalic anhydride, 2,5-disulfoterephthalic anhydride, methane sulfonic acid, ethanesulfonic acid, methionic acid, cyclopentanesulfonic acid, 1,1-ethanedisulfonic acid, 1,2-ethanedisulfonic acid, 1,2-ethanedisulfuric acid phonic 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, dimethyl 5-sulfosalicylate, trimethyl 4-sulfophthalate, and the like, and These salts are mentioned. Among them, 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, 5-sulfoisophthalic acid, and salts thereof.

By using an organic sulfonic acid compound as a polymerization catalyst, polymerization becomes possible without using a metal catalyst, and the content of metal components derived from the metal catalyst in the polyester resin of the present invention can be reduced. If the content of metal components is high, foreign matter may be generated during melt processing. The content of the metal component is preferably 1 ppm or less, more preferably 0.5 ppm or less, and even more preferably 0 ppm. Examples of metal-based catalysts include compounds such as antimony, germanium, tin, titanium, zinc, aluminum, iron, magnesium, potassium, calcium, sodium, manganese, nickel, and cobalt.

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.

Although the amount of the organic sulfonic acid compound to be added depends on the type, it is preferably 0.5×10 ⁻⁴ to 40×10 ⁻⁴ mol per 1 mol of the acid component constituting the polyester resin. .0×10 ⁻⁴ to 20.0×10 ⁻⁴ mol is more preferable. If the added amount exceeds the above range and is too small, it may not be possible to obtain a polyester resin with a high degree of polymerization, and fibers having excellent strength and dyeability may not be obtained. Alternatively, the content of diethylene glycol and triethylene glycol may not fall within a specific range. On the other hand, if the content exceeds the above range and is excessive, the content of triethylene glycol may become too large, or it may cause coloring of the polyester resin.

By setting the amount of the organic sulfonic acid-based compound to be added within the above range, the content of the sulfur component other than the aromatic dicarboxylic acid having a metal sulfonate group (that is, the sulfur component derived from the catalyst) in the obtained polyester resin can be reduced to , preferably 5 to 100 ppm, more preferably 6 to 60 ppm. If the content of the sulfur component is less than 5 ppm, the fibrous properties may be poor. On the other hand, if it exceeds 100 ppm, it may cause coloring of the polyester.

It is important to adjust the molar ratio of total glycol component/total acid component in the starting material to be subjected to the etherification reaction to 1.05 to 2.00. Thereby, the crystallinity of the obtained polyester resin can be made within the scope of the present invention, and the contents of diethylene glycol and triethylene glycol can be made within specific ranges.
G/A is preferably 1.10 to 1.80, more preferably 1.20 to 1.65. In order to adjust the G/A, if necessary, a glycol component such as ethylene glycol may be additionally added to the polyester raw material.

The etherification reaction temperature is preferably 240°C or higher, more preferably 240°C to 300°C, even more preferably 250°C to 280°C. If the temperature is lower than 240°C, the reaction may not proceed sufficiently, and the content of diethylene glycol and triethylene glycol may not be within the specific range. If the temperature exceeds 300° C., the decomposition of the esterified product proceeds during the reaction, and the workability of the fiber and the yarn properties of the fiber may deteriorate.

The etherification reaction time is preferably 5 to 120 minutes, more preferably 10 to 60 minutes. If it is less than 5 minutes, the reaction may not proceed sufficiently, and the content of diethylene glycol and triethylene glycol may not be within the specific range. If it exceeds 120 minutes, the etherification reaction proceeds too much, and the content of diethylene glycol and triethylene glycol may not fall within the specified range, or the decomposition of the esterified product may proceed during the reaction. The operability at the time of processing and the yarn quality characteristics as a fiber may deteriorate.

The etherification reaction is preferably allowed to proceed under normal pressure or increased pressure, and the pressure is preferably from 0 to 3.0 kg/cm ² G.

After the etherification reaction, a polycondensation reaction can be performed to obtain the polyester resin of the present invention. Examples of polycondensation reactions include melt polycondensation reactions. The polycondensation reaction may be carried out in one step, or may be carried out in multiple steps.

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 500-20 hPa, more preferably 200-30 hPa.

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

Furthermore, at the time of the polycondensation reaction, a hindered phenol-based antioxidant, a phosphorus compound capable of suppressing thermal decomposition of the resin, and titanium oxide for improving whiteness are optionally added together with the above polymerization catalyst. can also be added.

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), triethylene glycol-bis[3-(3-t-butyl-4-hydroxy-5-methylphenyl)propionate], 3,9-bis {2-[3-(3-t-butyl-4-hydroxy-5-methylphenyl)propionyloxy]-1,1′-dimethylethyl}-2,4,8,10-tetraoxaspiro[5,5 ] undecane and the like are used, but tetrakis[methylene-3-(3,5-di-t-butyl-4-hydroxyphenyl)propionate]methane is preferred from the viewpoint of effect and cost. These can be used alone or in combination of two or more.

Phosphorus compounds that can be used include, for example, phosphorous acid, phosphoric acid, trimethylphosphite, triphenylphosphite, tridecylphosphite, trimethylphosphate, tridecylphosphate, and triphenylphosphate. These can be used alone or in combination of two or more.

Titanium oxide is generally used as a delustering agent or white pigment for polyesters, but by adding an appropriate amount of titanium oxide to the polyester resin of the present invention, the whiteness of the fiber is improved. is preferable in that a woven or knitted fabric with a good color tone can be obtained. The amount of titanium oxide to be added is preferably 0.05 to 5 parts by mass with respect to 100 parts by mass of the polyester resin.

(Use of polyester resin)
The polyester resin of the present invention can be applied to various uses. Among them, it is suitable for fiber applications, but it can also be used for molding applications such as sheets, films and injection molded articles.

The fiber of the present invention is made of the polyester resin of the present invention.
The fiber of the present invention can be obtained, for example, by spinning using the polyester resin of the present invention. The spinning method and the like can be carried out according to known conditions. By using the polyester resin of the present invention, even ultrafine fibers having a single filament fineness of 0.8 decitex or less (preferably 0.6 to 0.3 decitex) can be obtained with good workability.

The fibers of the present invention may be, for example, monofilaments, multifilaments, or the like, and may be long fibers, short fibers, or the like.

The shape of the single fiber constituting the fiber of the present invention is not particularly limited, and may be not only a circular cross section but also a polygonal cross section such as a triangle or a square.
Moreover, since the polyester resin of the present invention has crystallinity within a specific range, it is possible to obtain a polyester fiber having a complicated cross-sectional shape such as a multi-leaf cross-sectional shape.

The fibers of the present invention include not only fibers in which all of the single fibers are formed of the polyester resin of the present invention, but also polyester resins of the present invention and other polyester resins (virgin polyester resins and other copolymer components). It may be a conjugate fiber that is conjugated with a polyester resin, etc.). Examples of the form of the composite fiber include core-sheath type, side-by-side type, and sea-island type.

When the fiber of the present invention is a multifilament, its characteristic values include, for example, a single filament fineness of 0.3 to 30 decitex, a single filament count of 2 to 300, a total fineness of 5 to 350, a strength of 1 to 5 cN/dtex, Examples include those having an elongation in the range of 10 to 400%.

The fiber of the present invention can be dyed with a cationic dye, and when dyed, does not cause mottling or color difference, and has excellent dyeability. Furthermore, it is excellent in filament properties such as elongation and strength.

EXAMPLES The present invention will be specifically described below based on examples, but the present invention is not limited to these. Measurement and evaluation were performed by the following methods.

(1) Intrinsic viscosity [η]
Measurement was performed at a temperature of 20° C. using an equal weight mixture of phenol and ethane tetrachloride as a solvent.

(2) Composition of polyester resin Dissolve 10 mg of sample in 1 mL of a mixed solvent of deuterated chloroform / deuterated trifluoroacetic acid = 9/1 (mass ratio), and ¹ by LA-400 type NMR manufactured by JEOL Ltd. H-NMR was measured, and the molar ratio of the dicarboxylic acid component and the glycol component was calculated from the proton peak integrated intensity of each component in the obtained chart.

(3) Melting point (Tm), glass transition temperature (Tg), crystallization exotherm, melting endotherm The melting point, glass transition temperature and melting heat value were measured at a temperature increase rate of 20°C/min, and the crystallization heat value was measured at a temperature decrease rate of 20°C/min.

(4) Content of sulfur component of catalyst A polyester resin is melt-molded at 300 ° C. to form a disc-shaped molded plate with a diameter of 3 cm and a thickness of 1 cm, and a calibration curve method is used using a fluorescent X-ray analyzer ZSX Primus manufactured by Rigaku. Quantitative analysis of sulfur components was performed by
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 ¹ H-NMR was analyzed with a JEOL LA-400 NMR. The molar ratio of 5-Na sulfoisophthalic acid diglycol ester (SIPG) was calculated from the proton peak integrated intensity of each component in the measured and obtained chart, and the sulfur content derived from SIPG was calculated therefrom.
The catalyst-derived sulfur content was calculated by subtracting the SIPG-derived sulfur content calculated by NMR from the sulfur content quantitatively analyzed by the fluorescent X-ray spectrometer.

(5) Workability of fibers (thread cut during spinning)
The case where the number of yarn cuts during continuous melt spinning for 24 hours was 3 times/(day/weight) or less was rated as "good", and the other cases were rated as "poor".
(6) Workability of fibers (cutting during drawing)
In the drawing process, the number of cut yarns generated when drawing was continuously performed for 6 hours was counted, and the cut yarn occurrence rate (%) was calculated and evaluated by the following formula.
Yarn occurrence rate (%) = {(total number of spindles for drawing) - (number of spindles that could be drawn without cutting for 6 hours)} / (total number of spindles for drawing) x 100
○: Cut yarn generation rate during stretching ≤ 5%
×: Cut yarn generation rate during stretching > 5%

(7) Thread Quality According to JIS L-1013, using Autograph DSS-500 manufactured by Shimadzu Corporation, strength and elongation were measured at a grip interval of 25 cm and a tensile speed of 30 cm.
In the present invention, the strength is preferably 2.0 cN/dtex or more, more preferably 3.0 cN/dtex or more. Also, the elongation is preferably 28% or more, more preferably 30% or more. Satisfying the above range for both strength and elongation is an index of excellent balance of yarn properties.

(8) Dyeability Using the obtained multifilament, a tubular knitted fabric was produced with a knitting machine (manufactured by Koike Kikai Seisakusho, number of needles: 300, hook diameter: 3.5 inches). The produced tubular knitted fabric was dyed with Astorazon Blue FRR and dyed with acetic acid, sodium acetate and Ionet as auxiliaries. w. f. Dyeing was performed at 130° C. for 30 minutes under the following conditions. The 30 dyed tubular knitted fabrics were visually observed to evaluate the presence or absence of staining streaks and staining spots.
○: The number of good products is 27 or more ×: The number of good products is 26 or less

(9) Normal pressure dyeability (L value after dyeing)
A tubular knitted fabric was produced from the obtained multifilament yarn using a knitting machine (manufactured by Koike Kikai Seisakusho, number of needles: 300, hook diameter: 3.5 inches).
The produced tubular knitted fabric was scouring at 60° C. for 20 minutes, then under normal pressure dyeing at 100° C. for 60 minutes under the following dyeing conditions, and air-dried. Next, after performing heat setting at 150° C. for 1 minute using a small pin tenter, a four-ply sample piece was prepared. The L value of this sample piece was measured with a color difference meter to evaluate dyeability. The lower the L value, the darker the color of the fiber, and it was judged that the dyeability was good, and the L value of 35 or less was accepted.
In addition, 30 dyed tubular knitted fabrics were visually evaluated for the presence or absence of staining streaks and staining spots, and the number of non-defective products having neither staining streaks nor staining spots was counted and evaluated as follows.
○: The number of good products is 27 or more ×: The number of good products is 26 or less (dyeing conditions)
Dye: Astrazon Blue 0.5% o. m. f.
Leveling agent: Acetic acid 0.2mL/L
Sodium acetate 0.2g/L
Bath ratio: 1:50

(10) Stretchability Sensory evaluation was performed by 10 panelists on the sample (tubular knitted fabric) used for dyeability evaluation. It was evaluated on a 10-point scale from 1 to 10, and the highest stretchability was given a perfect score of 10, and the average value of 10 people was shown. A score of 7 or more was evaluated as ◯, and a score of less than 7 was evaluated as x.

[Preparation of esterified product]
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, with a residence time of 8 hours. An esterified product (terephthalic acid: ethylene glycol = 100:111 (molar ratio)) was obtained.

Example 1
[Polyester resin]
49 parts by mass of the heat-melted esterified product and 6.0 parts by mass of 5-Na sulfoisophthalic acid diglycol ester (SIPG) as a polymerization catalyst were charged into a polycondensation reaction vessel heated to 280 ° C., and 5-sulfosalicylic acid di Hydrate (SS) was added in an amount of 2.0×10 ⁻⁴ mol/mol of acid component, and an etherification reaction was carried out at 260° C. for 10 minutes under normal pressure. Next, while maintaining the temperature of the reactor at 280° C., the system pressure was gradually reduced to 0.5 hPa or less after 60 minutes. A polycondensation reaction was carried out for 3 hours while stirring under these conditions to obtain a polyester resin.

[Manufacturing of long fibers]
After drying the obtained polyester resin, it is spun at a spinning temperature of 293° C. using a spinneret having 84 discharge holes, and is wound at a speed of 2900 m/min while cooling and oiling. A drawn yarn was obtained. After drawing under the conditions of a roll heater temperature of 80° C., a plate heater of 150° C. and a drawing speed of 600 m/min, the multifilament was wound up to obtain a multifilament (drawn yarn) of 45 decitex/84 filaments.

Examples 2-6, Comparative Examples 1-7
[Polyester resin]
As shown in Table 1, the esterification product, the amount of 5-Na sulfoisophthalic acid diglycol ester (SIPG) added, the amount of 5-sulfosalicylic acid dihydrate (SS) added, and the etherification reaction conditions are shown in Table 1. A polyester resin was obtained by performing the same operation as in Example 1, except that it was changed to that shown.
Then, a multifilament was obtained in the same manner as in Example 1.

Comparative example 8
Instead of 5-sulfosalicylic acid dihydrate (SS), antimony trioxide (Sb) was used, and the esterified product, the amount of 5-Na sulfoisophthalic acid diglycol ester (SIPG) added, and the amount of antimony trioxide (Sb) A polyester resin was obtained in the same manner as in Example 1, except that the amount added and the etherification reaction conditions were changed to those shown in Table 1. Then, a multifilament was obtained in the same manner as in Example 1.

Example 7
2.1 parts by mass of isophthalic acid (IPA) was added to a polycondensation reactor, and the esterified product, the amount of 5-Na sulfoisophthalic acid diglycol ester (SIPG) added, and 5-sulfosalicylic acid dihydrate (SS) were added. A polyester resin was obtained in the same manner as in Example 1, except that the addition amount of and the etherification reaction conditions were changed to those shown in Table 1.
The obtained polyester resin and the polyester resin obtained in Example 3 are used as the other polyester resin, and these resins are dried and then supplied to a composite spinning melt extruder in equal mass, spinning at a spinning temperature of 290. °C, the two components were combined upstream of a spinneret having 12 discharge holes, joined side-by-side and spun. After the spun yarn was cooled and solidified, it was wound up at a speed of 3000 m/min while applying oil to obtain an undrawn yarn. Then, after heat treatment with rollers at a temperature of 85° C., the film was stretched at a draw ratio of 1.7 and simultaneously heat treated at 185° C. (heat plate temperature) to obtain a multifilament of 56 decitex/12 filament conjugate fibers.

Examples 8 and 9
By changing the amount of isophthalic acid (IPA) added, the amount of esterified product, 5-Na sulfoisophthalic acid diglycol ester (SIPG) added, the amount of 5-sulfosalicylic acid dihydrate (SS) added, and the etherification reaction conditions A polyester resin was obtained in the same manner as in Example 7, except that the was changed to that shown in Table 1. Then, a multifilament was obtained in the same manner as in Example 7.

Example 10
1.8 parts by mass of adipic acid (AD) was added to a polycondensation reactor, and the esterified product, the amount of 5-Na sulfoisophthalic acid diglycol ester (SIPG) added, and 5-sulfosalicylic acid dihydrate (SS) were added. A polyester resin was obtained in the same manner as in Example 1, except that the addition amount of and the etherification reaction conditions were changed to those shown in Table 1. Then, a multifilament was obtained in the same manner as in Example 1.

Examples 11 and 12
By changing the amount of adipic acid (AD) added, the esterification product, the amount of 5-Na sulfoisophthalic acid diglycol ester (SIPG) added, the amount of 5-sulfosalicylic acid dihydrate (SS) added, and the etherification reaction conditions A polyester resin was obtained in the same manner as in Example 10, except that the was changed to that shown in Table 1. Then, a multifilament was obtained in the same manner as in Example 1.

Table 1 shows the raw material composition and production conditions of the polyester resins in Examples and Comparative Examples.

Table 2 shows the characteristic values of the polyester resins and fibers obtained in Examples and Comparative Examples.

As shown in Tables 1 and 2, the polyester resins obtained in Examples 1 to 12 had diethylene glycol and triethylene glycol contents within the range defined by the present invention, and thus had excellent dyeability with cationic dyes. In addition, it was possible to obtain a fiber excellent in filament properties (strength, elongation) with good workability.
Among them, the composite fibers using the polyester resin obtained in Examples 7 to 9 were also excellent in stretchability. The polyester resin fibers obtained in Examples 10 to 12 were also excellent in normal pressure dyeability.

On the other hand, in Comparative Example 1, since the content of the aromatic dicarboxylic acid having a metal sulfonate group was high, the content of glycol components other than ethylene glycol in the polyester resin was increased. As a result, the resulting resin was amorphous and had poor heat resistance, and had poor operability in spinning, and could not be drawn, and could not be evaluated as a fiber.

In Comparative Example 2, since the content of the aromatic dicarboxylic acid having a metal sulfonate group was low, the content of glycol components other than ethylene glycol in the polyester resin was low. As a result, the resin had a high melting point, poor spinning operability, and poor dyeability.

In Comparative Example 3, since no etherification reaction was performed, the content of glycol components other than ethylene glycol in the polyester resin was reduced, resulting in poor spinning operability and poor dyeability.

In Comparative Example 4, since the amount of 5-sulfosalicylic acid dihydrate added as a polymerization catalyst was large, the content of glycol components other than ethylene glycol in the polyester resin increased, and as a result, the polyester resin was amorphous and heat-resistant. It became a resin with low toughness. The operability in spinning was poor and drawing could not be performed, so the fiber was not evaluated.

In Comparative Example 5, since the amount of 5-sulfosalicylic acid dihydrate added as a polymerization catalyst was small, the content of glycol components other than ethylene glycol was small. As a result, the workability in stretching was poor, and the dyeability was also poor.

In Comparative Example 6, since the temperature of the etherification reaction was lowered, the content of glycol components other than ethylene glycol in the polyester resin was reduced. As a result, the spinnability was poor, and the dyeability was also poor.

In Comparative Example 7, the content of glycol components other than ethylene glycol in the polyester resin was increased by lengthening the etherification reaction time. As a result, an amorphous resin with low heat resistance was obtained. The operability in spinning was poor, drawing was not possible, and the fiber was not evaluated.

In Comparative Example 8, antimony trioxide was added instead of 5-sulfosalicylic acid dihydrate (SS) as the polymerization catalyst, so the triethylene glycol content in the polyester resin was reduced. As a result, the workability was poor and the dyeability was also poor.

Claims (5)

When the total amount of the acid component is 100 mol%, it contains 70 mol% or more of terephthalic acid, 0.5 to 6.0 mol% of an aromatic dicarboxylic acid having a metal sulfonate group, and the total amount of the glycol component is 100 mol. %, a polyester resin containing 85 mol % or more of ethylene glycol and 3 to 15 mol % of a glycol component other than ethylene glycol, and the crystallization heat value when measured by DSC at a cooling rate of 20 ° C./min. is 20 J/g or less, and the melting endotherm is 5 J/g or more when measured at a heating rate of 20°C/min. 2. The polyester resin according to claim 1, further comprising 2 to 18 mol % of an aliphatic dicarboxylic acid having 5 to 10 carbon atoms per 100 mol % of the total acid component. 2. The polyester resin according to claim 1, further comprising 5 to 16 mol % of isophthalic acid in the acid component when the total amount of the acid component is 100 mol %. A fiber comprising the polyester resin according to any one of claims 1 to 3. A method for producing a polyester resin according to any one of claims 1 to 3, wherein an organic sulfonic acid compound is added to the polyester raw material, and the molar ratio of total glycol component/total acid component is 1.5. 05 to 2.00, and heating at a temperature of 240 ° C. or higher for 5 to 120 minutes at normal pressure or under pressure to etherify the glycol component. A method for producing a polyester resin. .