JP2006291423A - Polytrimethylene terephthalate based polyester fiber - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a polytrimethylene terephthalate based polyester fiber low in deposition of cyclic dimers in dying, weaving and knitting, stably produced, excellent in quality control. <P>SOLUTION: The invention relates to the polytrimethylene terephthalate based fiber comprising trimethylene terephthalate as a principal repeating unit, having ≤1.5% by mass of the cyclic dimer content and 0.5-1.5 dL/g of intrinsic viscosity (measured in orthochlorophenol solution, at 35°C). <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a polytrimethylene terephthalate-based polyester fiber, and more particularly to a polytrimethylene terephthalate-based polyester fiber having a low cyclic dimer content and excellent performance in quality control in a dyeing process.

Polyester is widely used in fibers, films and other molded articles because of its excellent mechanical, physical and chemical performance.
Among these, polytrimethylene terephthalate fibers have recently attracted attention because of their soft texture, excellent elastic recovery, and easy dyeability, which were not found in conventional polyester fibers represented by polyethylene terephthalate.
However, this polytrimethylene terephthalate is likely to form a cyclic dimer that is an oligomer during polycondensation, but this cyclic dimer adheres as a foreign matter in the vicinity of the spinneret in the spinning process, causing thread breakage, There is a problem in that oligomers are precipitated during weaving and knitting to reduce processing stability. In order to solve such problems, a polytrimethylene terephthalate resin having an oligomer content of 1% by mass or less by performing solid-phase polymerization of polytrimethylene terephthalate under reduced pressure has been proposed (for example, patents). Reference 1). If this method is used, the amount of cyclic dimer in the polytrimethylene terephthalate chip can be greatly reduced, but the cyclic dimer is regenerated at the time of remelting for melt molding, so it has not led to fundamental improvement. .

On the other hand, as a method for reducing the activity of the catalyst, a method of adding a phosphoric acid compound has been proposed (see Patent Document 2). In this method, a cyclic dimer removing device is used in combination. If this technique is used, the cyclic dimer may surely be suppressed, but an expensive facility called a cyclic dimer removing device is required.
JP-A-8-311177 JP 2004-51921 A

  The purpose of the present invention is to reduce the amount of regenerated cyclic dimer at the time of melt molding, thereby reducing the cyclic dimer content in the polyester fiber, thereby reducing the amount of oligomer precipitation in the dyeing, weaving and knitting processes. It is to provide a polyester fiber having excellent performance in stability and quality control.

  The present invention is a fiber made of polyester having a main repeating unit as a trimethylene terephthalate unit, the cyclic dimer content is 1.5% by mass or less, and the intrinsic viscosity (measured at 35 ° C.). ) Relates to polytrimethylene terephthalate fibers in the range of 0.5 to 1.5 dL / g.

  According to the present invention, since the amount of the cyclic dimer in the polyester fiber is reduced due to the small amount of the regenerated cyclic dimer at the time of melt molding, the quality control in the dyeing, weaving and knitting processes is excellent. A polyester fiber having performance can be provided.

Hereinafter, the present invention will be described in more detail.
The polyester fiber of the present invention is a fiber made of polyester having trimethylene terephthalate as a main repeating unit. This polyester may be a copolymerized polytrimethylene terephthalate obtained by copolymerizing a third component other than the component constituting the trimethylene terephthalate unit. The third component (copolymerization component) may be either a dicarboxylic acid component or a glycol component. Here, “main” means 90 mol% or more in all repeating units.

As the component preferably used as the third component, as the dicarboxylic acid component, aromatic dicarboxylic acid such as 2,6-naphthalenedicarboxylic acid, isophthalic acid or phthalic acid, adipic acid, azelaic acid, sebacic acid or decanedicarboxylic acid, etc. Aliphatic dicarboxylic acids such as aliphatic dicarboxylic acids and cyclohexanedicarboxylic acids, and the glycol components include ethylene glycol, tetramethylene glycol, diethylene glycol, polyethylene glycol, hexamethylene glycol, cyclohexanedimethanol or 2,2-bis [4 -(2-hydroxyethoxy) phenyl] propane and the like are exemplified, and these can be used alone or in combination of two or more.
The method for producing the polyester used in the present invention is not particularly limited. A method in which terephthalic acid is directly esterified with trimethylene glycol and then polymerized, and an ester-forming derivative of terephthalic acid is transesterified with trimethylene glycol. Any of the polymerization methods may be employed.

  The polyester polymerization catalyst used in the present invention is not particularly limited, but it is preferable to use a titanium compound as the polymerization catalyst. Here, the titanium compound used as a catalyst is preferably an organic titanium compound soluble in a polymer. The content of the titanium compound is not particularly limited, but from the viewpoint of polycondensation reactivity, the hue of the resulting polyester, and heat resistance, it is contained in an amount of about 2 to 150 mmol% as a titanium metal element with respect to the total dicarboxylic acid component. It is preferable.

  Here, when a method of polymerizing an ester-forming derivative of terephthalic acid after undergoing a transesterification reaction with trimethylene glycol and adopting a polymerization method, as a transesterification reaction catalyst, usually a calcium compound, a magnesium compound, a manganese compound, a zinc compound, etc. A catalyst used as a transesterification catalyst for polyester may be used in combination. However, usually, a method in which the above-described titanium compound is used as both a transesterification catalyst and a polymerization catalyst is preferably employed.

  As the titanium compound used in the present invention, it is preferable to use a titanium compound that is soluble in polyester from the viewpoint of reducing foreign matters caused by the catalyst. The titanium compound is not particularly limited, and examples thereof include a general titanium compound as a polyester polycondensation catalyst such as alkoxytitanium such as titanium acetate and tetra-n-butoxytitanium. A product obtained by reacting a carboxylic acid or an anhydride thereof is preferred.

The polyester fiber of the present invention needs to have a cyclic dimer content of 1.5% by mass or less. When the cyclic dimer content exceeds 1.5% by mass, the processing stability of the dyeing, weaving and weaving processes decreases, which is not preferable. The cyclic dimer content is preferably in the range of 1.4% by mass or less. More preferably, the range is 3% by mass or less. In order to make the amount of the cyclic dimer 1.5% by mass or less, it is effective to set the intrinsic viscosity in the melt polymerization stage to 0.5 to 1.0 dL / g and to perform solid phase polymerization after the melt polymerization.
Here, the “cyclic dimer” is known to be a mixture of a linear oligomer (1) and a cyclic oligomer (2) as shown in the following structure, and about 90% by mass is a cyclic oligomer (formula (In (2), q has a structure corresponding to 1). Since the cyclic dimer has a particularly high sublimation property and hot water solubility, it becomes a main causative substance that causes the problems described above.
_{(OCH 2 CH 2 CH 2 OOC} -Ph-CO) p ...... (1)

_{OCH 2 CH 2 CH 2 OOC-} Ph-CO
｜ ｜ (2)
_{(OC-Ph-COOCH 2 CH} 2 CH 2 O) q
[Wherein p ≦ 10 and q = 1 to 4. ]

The polyester fiber of the present invention needs to have an intrinsic viscosity (measured in an orthochlorophenol solution at 35 ° C.) in the range of 0.5 to 1.5 dL / g. When the intrinsic viscosity is less than 0.5 dL / g, the mechanical strength of the finally obtained fiber becomes insufficient. On the other hand, when it exceeds 1.5 dL / g, the handleability is lowered, which is not preferable. The intrinsic viscosity is more preferably in the range of 0.55 to 1.45 dL / g, and most preferably in the range of 0.6 to 1.4 dL / g.
In order to bring the intrinsic viscosity of the polyester fiber of the present invention into the above appropriate range, a solid-state polymerized polyester chip is preferably used. As a specific example of this solid-state polymerization, the pellets of the polyester composition are kept at a high temperature of the melting point or lower, preferably in the range of 190 to 210 ° C., and a high vacuum of 150 Pa or lower or a nitrogen stream is used. A method of stirring or allowing to stand for several tens of hours to hours can be mentioned. Further, this solid phase polymerization may be continuous or batchwise.

  The polyester fiber of the present invention preferably has a phosphorus element content in the range of 10 to 1,000 ppm with respect to the polyester fiber. When the amount of phosphorus element is less than 10 ppm, the amount of regenerated cyclic dimer increases, which is not preferable. On the other hand, when the amount of phosphorus element exceeds 1,000 ppm, the heat resistance of the resulting polyester composition is lowered, which is not preferable. The amount of phosphorus element in the polyester fiber of the present invention is preferably in the range of 15 to 700 ppm, more preferably in the range of 20 to 500 ppm.

  In order to satisfy the phosphorus element content described above, the polyester fiber of the present invention contains at least one of phosphorus compounds represented by the following formulas (I) to (III), and the total phosphorus compound is 0.01 to 0.5% by mass is preferably contained. Here, when the content of the following phosphorus compound is less than 0.01% by mass, the amount of regenerated cyclic dimer is unfavorably increased. On the other hand, when the content exceeds 0.5% by mass, the heat resistance of the resulting polyester composition is lowered. Therefore, it is not preferable. As for content of the said phosphorus compound, the range of 0.03-0.3 mass% is further more preferable.

[Wherein R ₁ , R ₂ and R ₃ are hydrocarbon groups having 1 to 10 carbon atoms, and may be the same or different. Moreover, n is an integer of 1-5. M is an alkali metal atom or an alkaline earth metal atom. When M is an alkali metal atom, m = 1, and when M is an alkaline earth metal atom, m = 2. ]

[In the above formula, R ₄ , R ₅ and R ₆ are a hydrogen atom or a hydrocarbon group having 1 to 10 carbon atoms, which may be the same or different. x is 1. ]

[In the above formula, R ₇ and R ₈ are a hydrogen atom or a hydrocarbon group having 1 to 10 carbon atoms, and y is 0 or 1. ]

In the above formula (I), preferred hydrocarbon groups having 1 to 10 carbon atoms for R ₁ , R ₂ and R ₃ are methyl group, ethyl group, propyl group, isopropyl group, butyl group, tertiary butyl group, phenyl Group, benzyl group and the like, and methyl group, ethyl group, isopropyl group and tertiary butyl group are preferable. N is an integer of 1 to 5, preferably 1 or 2. Further, M is an alkali metal atom or an alkaline earth metal atom. Examples of the alkali metal atom include lithium, sodium, potassium, rubidium, and examples of the alkaline earth metal atom include calcium, magnesium, strontium, barium, etc. It is calcium. When M is an alkali metal atom, m = 1, and when M is an alkaline earth metal atom, m = 2.

  Specific examples of the above formula (I) are calcium diethylbis (((3,5-dimethyl-4-hydroxyphenyl) methyl) phosphonate), magnesium diethylbis (((3,5-dimethyl-4-hydroxyphenyl) methyl). ) Phosphonate), calcium diethylbis (((3,5-bis (1,1-dimethylethyl) -4-hydroxyphenyl) methyl) phosphonate), magnesium diethylbis (((3,5-bis (1,1- Dimethylethyl) -4-hydroxyphenyl) methyl) phosphonate), calcium diethylbis (((3,5-bis (1,1-dimethylethyl) -4-hydroxyphenyl) ethyl) phosphonate), magnesium diethylbis ((( 3,5-bis (1,1-dimethylethyl) -4-hydroxyphenyl) ethyl) Sulfonate), sodium ethyl (((3,5-dimethyl-4-hydroxyphenyl) methyl) phosphonate), potassium ethyl (((3,5-dimethyl-4-hydroxyphenyl) methyl) phosphonate), sodium ethyl ((( 3,5-bis (1,1-dimethylethyl) -4-hydroxyphenyl) methyl) phosphonate), potassium ethyl (((3,5-bis (1,1-dimethylethyl) -4-hydroxyphenyl) methyl) Phosphonate), sodium ethyl (((3,5-bis (1,1-dimethylethyl) -4-hydroxyphenyl) ethyl) phosphonate), potassium ethyl (((3,5-bis (1,1-dimethylethyl) And -4-hydroxyphenyl) ethyl) phosphonate).

In the above formula (II), R ₄ , R ₅ and R ₆ are a hydrogen atom or a hydrocarbon group having 1 to 10 carbon atoms, preferably as a hydrocarbon group having 1 to 10 carbon atoms, preferably a methyl group, Examples thereof include an ethyl group, a propyl group, an isopropyl group, a butyl group, a tertiary butyl group, a phenyl group, and a benzyl group, and a methyl group, an ethyl group, an isopropyl group, and a tertiary butyl group are preferable. X is 1. Among these, R ₄ , R ₅ and R ₆ are most preferably hydrogen atoms, all methyl groups, or all ethyl groups.

Specific examples of the phosphorus compound represented by the above formula (II) include trimethyl phosphite, triethyl phosphite, triisopropyl phosphite, tri-n-butyl phosphite, tridecyl phosphite, triphosphite phosphite. Examples include phenyl.
In the above formula (III), R ₇ and R ₈ are a hydrogen atom or a hydrocarbon group having 1 to 10 carbon atoms. Preferred examples of the hydrocarbon group having 1 to 10 carbon atoms include methyl group, ethyl group, normal propyl group, isopropyl group, normal butyl group, isobutyl group, tertiary butyl group, phenyl group, and benzyl group. In the above formula (III), the phosphorus atom is represented as a pentavalent compound. However, in the case of a compound having a pentavalent phosphorus atom and a trivalent tautomer of the phosphorus atom, the trivalent phosphorus compound is It is contained in the phosphorus compound represented by the above formula (III).
Specific examples of the phosphorus compound represented by the above formula (III) include phosphorous acid, dimethyl phosphite, diethyl phosphite, diisopropyl phosphite, dibutyl phosphite, diphenyl phosphite, phenylphosphinic acid, phenyl Examples include methyl phosphinate, ethyl phenylphosphinate, phenyl phenylphosphinate, benzylphosphinic acid, methyl benzylphosphinate, ethyl benzylphosphinate, phenyl benzylphosphinate and the like.

  The content of the phosphorus compound in the polyester fiber can be quantified by a nuclear magnetic resonance spectrum in addition to quantitative analysis of the phosphorus element.

There is no particular limitation on the method of adding the phosphorus compound represented by the above formulas (I) to (III) preferably contained in the polyester fiber of the present invention into the polyester fiber.
For example, it can be added to the polymerization process at any stage during the polymerization of the polyester, or the polytrimethylene terephthalate polymer produced can be spun or dissolved in a powder, liquid, or solvent in the previous stage. Examples thereof include a method of melt blending the phosphorus compound using a twin screw extruder, a melt blend method using a master batch method, and the like.

  The production method for producing the polyester fiber of the present invention is not particularly limited, and a conventionally known method for melt spinning polyester can be used. For example, the polyester composition of the present invention is preferably produced by melt spinning in the range of 240 ° C. to 280 ° C., and the spinning speed is preferably 400 to 5,000 m / min. When the spinning speed is within this range, the polyester fiber obtained has sufficient strength and can be wound stably. In addition, the stretching can be continuously performed after winding the polyester fiber or without winding it once. By this treatment operation, a drawn yarn can be obtained. Furthermore, the polyester fiber of the present invention is preferably subjected to an alkali weight reduction treatment in order to enhance the texture.

  When the polyester fiber of the present invention is produced, the polytrimethylene terephthalate-based polyester used has a cyclic dimer content of 1.5% by mass or less and an intrinsic viscosity of 0.55 to 1.6 dL / g. It is preferred to melt spin the polyester in Here, when the polyester used deviates from the above range, it is difficult to produce a polyester fiber that exhibits the effects of the present invention. In order to make the polyester fiber within the scope of the present invention, it is preferable to blend the phosphorus compounds represented by the above formulas (I) to (III) at any stage until the polyester is melt-spun. The

  When producing the polyester fiber of the present invention, the shape of the die used at the time of spinning is not limited, and any of circular, irregular, solid, hollow and the like can be adopted.

The dyeing process of the polyester fiber of the present invention can be dyed yarn through each process of general scouring, dyeing, alkali reduction washing, finishing agent treatment, dehydration, and drying. As the dyeing form, general cheese dyeing or case dyeing is preferably employed.
The dye used in the product of the present invention is preferably an easily alkali-decomposable disperse dye and dyed at 110 to 120 ° C. under high temperature and high pressure.
Further, the product of the present invention is an easily dyeable fiber, and the dyeing start temperature is about 20 ° C. lower than that of general polyethylene terephthalate fiber, and the heating rate is suppressed to about 50% from the viewpoint of preventing dyeing spots. It is preferable.

  Further, the polyester composition chip and fiber of the present invention may contain a small amount of additives as necessary, such as lubricants, pigments, dyes, antioxidants, solid phase polycondensation accelerators, fluorescent whitening agents, antistatic agents, antibacterial agents. An agent, an ultraviolet absorber, a light stabilizer, a heat stabilizer, a light-shielding agent, or a matting agent may be contained. In particular, titanium oxide as a matting agent is preferably added. As titanium oxide, 0.01 to 10% by mass of a titanium oxide having an average particle diameter of 0.01 to 2 μm is finally obtained. It is preferable to add them.

Hereinafter, the present invention will be described more specifically with reference to examples. However, the scope of the present invention is not limited to these examples. In addition, each value in an Example was measured by the method of the following description.
(1) Intrinsic viscosity:
The intrinsic viscosity of the polyester fiber was determined from the viscosity value measured at 35 ° C. in an orthochlorophenol solution.

(2) Measurement of phosphorus content in polyester composition:
The sample was heated and melted to prepare a circular disk, and quantified using a fluorescent X-ray apparatus ZSX100e type manufactured by Rigaku Corporation.

(3) Cyclic dimer content:
An apparatus in which two Waters GPC columns TSKgel G2000H8 were connected to a Waters 486 type liquid chromatograph was used. Using chloroform as a developing solvent, a sample obtained by dissolving 1 mg of a sample in 1 ml of hexafluoroisopropanol and diluting to 10 ml with chloroform was injected, and the weight percentage in the polymer was determined from a standard cyclic dimer calibration curve.

(4) Determination of phosphorus compound content in polyester fiber:
After dissolving the sample in deuterated trifluoroacetic acid / deuterated chloroform = 1/1 mixed solvent, JEOL A-600 manufactured by JEOL Ltd., superconducting FT-NMR was used to determine the nuclear magnetic resonance spectrum ( ¹ H- NMR). The contents of the phosphonate compound and the like were quantified from the spectrum pattern according to a conventional method.

(5) Tensile strength, tensile elongation:
Measurement was performed in accordance with the method described in JIS L1070.

Example 1
A mixture of 100 parts by mass of dimethyl terephthalate and 70.5 parts by mass of trimethylene glycol was charged with 0.053 parts by mass of tetra-n-butyl titanate into a reactor equipped with a stirrer, a rectifying column and a methanol distillation condenser. The ester exchange reaction was carried out while gradually raising the temperature from 140 ° C. and distilling methanol produced as a result of the reaction out of the system. The internal temperature reached 210 ° C. 3 hours after the start of the reaction.
The resulting reaction product was then transferred to another reactor equipped with a stirrer and a glycol distillation condenser, and calcium diethyl bis (((3,5-bis (1,1-dimethylethyl) -4-hydroxyphenyl ) Methyl) phosphonate) (alias: calcium bis {ethyl ((3,5-bis (1,1-dimethylethyl) -4-hydroxyphenyl) methyl) phosphonate}) (trade name: Irganox 1425, Ciba Specialty Chemicals) In the above formula (I), after adding 1.06 parts by mass of R ₁ = R ₂ = t-butyl group, R ₃ = ethyl group, n = 1, M = Ca), gradually from 210 ° C. to 265 ° C. While raising the temperature, the polymerization reaction was carried out while reducing the pressure from normal pressure to a high vacuum of 70 Pa. While tracing the melt viscosity of the reaction system, the polymerization reaction was terminated when the intrinsic viscosity reached 0.70 dL / g.
The molten polymer was extruded into cooling water in the form of a strand from the bottom of the reactor and cut into chips by using a strand cutter.

  90 parts by mass of polytrimethylene terephthalate chip (manufactured by Shell: Cortera CP50921P) having an intrinsic viscosity of 0.93 dL / g and a cyclic dimer content of 1.05% by mass was chip-blended with respect to 10 parts by mass of the obtained chip, 75 After drying at 125 ° C. for 1 hour and at 125 ° C. for 5 hours, it was melted at 260 ° C. using an extrusion spinning machine having a spinneret having 36 circular spinning holes with a hole diameter of 0.27 mm, and the discharge rate was 34 g / min. An undrawn yarn was obtained by spinning at 2,400 m / min. The obtained undrawn yarn was subjected to a drawing machine having a heating roller at 60 ° C. and a plate heater at 160 ° C., and drawn at a draw ratio of 1.7 times to obtain a drawn yarn of 83 dtex / 36 filaments. The results are shown in Table 1.

Examples 2-4
In Example 1, except that the compound shown in Table 1 was used instead of calcium diethylbis (((3,5-bis (1,1-dimethylethyl) -4-hydroxyphenyl) methyl) phosphonate). 1 was performed. The results are shown in Table 1.

Example 5
A polytrimethylene terephthalate chip (manufactured by Shell: Cortera CP50921P) having an intrinsic viscosity of 0.93 dL / g and a cyclic dimer content of 1.05% by mass is dried at 75 ° C. for 1 hour and at 125 ° C. for 5 hours, and then a twin-screw extruder And melted at 260 ° C., and the content of calcium diethylbis (((3,5-bis (1,1-dimethylethyl) -4-hydroxyphenyl) methyl) phosphonate) from the side feeder is 0.1 mass. It was added while adjusting to be%, and melt spinning and stretching were carried out as they were in the same manner as in Example 1. The results are shown in Table 1.

Comparative Example 1
Example 1 except that only a polytrimethylene terephthalate chip (manufactured by Shell: Cortera CP50921P) having an intrinsic viscosity of 0.93 dL / g and a cyclic dimer content of 1.05% by mass was melt-spun and stretched. As well as. The results are shown in Table 1.

Examples 6 to 10, Comparative Example 2
The fibers obtained in Examples 1 to 5 and Comparative Example 1 were used and dyed, and then the amount of cyclic dimer generated was measured.
The dyeing method used was a normal dyeing method in which no oligomer (cyclic dimer) dispersant was added in the dyeing step, and no high-temperature waste liquid apparatus was used. It carried out at 1 kg from the meaning which measures the cyclic | annular dimer generation amount of this invention product Examples 1-5 and the comparative product 1 which were used.
Moreover, all the dyeing methods of Examples 6 to 10 and Comparative Example 2 were performed under the same conditions.
The dyeing method used was a cheese dyeing method, the lower winding used an SSP winder (manufactured by Kozu Seisakusho), the winding density was unified to 0.65 g / cm ³ , and the method was replaced with a dyeing tube. In order to prevent yarn disturbance, a method of wrapping with a net was adopted.

1. Scouring process:
A scouring agent SSK-15A 1 g / L (manufactured by Matsumoto Yushi Seiyaku Co., Ltd.) and chelating agent Marpon A-40L 0.5 g / L (manufactured by Matsumoto Yushi Seiyaku Co., Ltd.) were added at 40 ° C. with hot water, and the temperature was raised 1 ° C./min. The treatment was carried out at 80 ° C. for 20 minutes.
2. Dyeing process dyes are TERASIL BLACK BFR 3.5% owf (manufactured by Ciba Specialty Chemicals), leveling agent Lebenol V150 0.5% owf (manufactured by Kitahiro Chemical), PH adjuster 80% acetic acid 0.3 g / L. The hot water temperature was 40 ° C., the temperature was raised to 115 ° C. at a rate of 1 ° C./min, and dyeing was performed for 60 minutes.
3. Alkaline reduction washing process Cationic surfactant Marvelin S-1000 1 g / L (manufactured by Matsumoto Yushi Seiyaku Co., Ltd.), NAOH 2 g / L, hydrosulfite 2 g / L are added at a hot water temperature of 40 ° C., and the temperature is increased by 1 ° C./min. The treatment was performed at a temperature rate of 70 ° C. for 15 minutes.
4). Finishing agent application treatment step Brian LC-23K 4% owf (manufactured by Matsumoto Yushi Seiyaku Co., Ltd.) was treated at 50 ° C. for 10 minutes, followed by dehydration drying.
5. Finish Winding Process Using the pineapple cone winding 3 ° 51'8 inch traverse winder (manufactured by Murata Machinery Co., Ltd.) having a cam traverse mechanism, the dyed yarns of Examples 6 to 10 and Comparative Example 2 were wound at 450 m / min. I rolled it up.
In this process, the feeler gate tension in the yarn path portion was tested at two levels of 9.8 cN and 0 cN.
The cyclic dimer generated at the time of winding up under the above conditions was filtered through a 4 μ-hole filter paper, and mass% was calculated after weight measurement.

Level 1: In the winding state at the feeler gate tension of 9.8 cN, the yarn of Comparative Example 2 became frequent due to frequent oligomer breakage 10 minutes after the start of winding, and operation was impossible.
In the products of the present invention (Examples 6 to 10), although a trace amount of cyclic dimer was observed, there was no thread breakage and no problem occurred.
Level 2: The winding state with the feeler gate tension set to 0 cN was a state where the dyed yarn of Comparative Example 2 started to break after 30 minutes from the start of winding.
The products of the present invention (Examples 6 to 10) were found to be very stable from the viewpoint of operability, although generation of a cyclic dimer was recognized, but there was no thread breakage once in 1 kg winding.
The results are summarized in Table 2.

  As is clear from Tables 1 and 2, the polyester fiber of the present invention produced little cyclic dimer in the dyeing process, and the process was very stable.

ADVANTAGE OF THE INVENTION According to this invention, the polyester fiber which has the performance excellent in the quality control in dyeing, weaving, and knitting process can be provided. In addition, the polyester fiber of the present invention retains ordinary mechanical properties and can be sufficiently used for conventionally used polytrimethylene terephthalate fibers.

Claims (5)

  It is a fiber made of polyester whose main repeating unit is a trimethylene terephthalate unit, the cyclic dimer content is 1.5% by mass or less, and the intrinsic viscosity (measured at an orthochlorophenol solution at 35 ° C.) is 0.00. Polytrimethylene terephthalate polyester fiber in the range of 5 to 1.5 dL / g.   The polytrimethylene terephthalate polyester fiber according to claim 1, wherein the amount of phosphorus element in the polyester fiber is in the range of 10 to 1,000 ppm with respect to the polyester fiber. The polyester fiber contains at least one of phosphorus compounds represented by the following formulas (I) to (III) as a phosphorus compound, and the total of the phosphorus compounds is 0.01 to 0.5% by mass. The polytrimethylene terephthalate polyester fiber according to 1 or 2.

[In the above formula, R ₁ , R ₂ and R ₃ are hydrocarbon groups having 1 to 10 carbon atoms, which may be the same or different. Moreover, n is an integer of 1-5. M is an alkali metal atom or an alkaline earth metal atom. When M is an alkali metal atom, m = 1, and when M is an alkaline earth metal atom, m = 2. ]

[In the above formula, R ₄ , R ₅ and R ₆ are a hydrogen atom or a hydrocarbon group having 1 to 10 carbon atoms, which may be the same or different. x is 1. ]

[In the above formula, R ₇ and R ₈ are a hydrogen atom or a hydrocarbon group having 1 to 10 carbon atoms, and y is 0 or 1. ]   When the polytrimethylene terephthalate polyester having a cyclic dimer content of 1.5% by mass or less and an intrinsic viscosity of 0.55 to 1.6 dL / g is melt-spun, until the polyester is melted The polytri of any one of claims 1 to 3, wherein the phosphorus compounds represented by the formulas (I) to (III) are blended with the polyester and melt-spun in any of the steps. A method for producing methylene terephthalate-based polyester fibers. The dyed polytrimethylene terephthalate-based polyester fiber according to any one of claims 1 to 3, which is obtained by performing a dyeing process.