JP2007045891A - Method for treating polyester, polyester obtained thereby and polyester fiber - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a polyester forming a small amount of a cyclic dimer reproduced at melt forming, providing a stable processing condition at melt spinning, depositing a small amount of oligomers at weaving and knitting to enable the stable production of a textile, and having excellent properties in quality control at dyeing step. <P>SOLUTION: The method for treating the polyester having a main repeating unit consisting of a trimethylene terephthalate unit involves treating the polyester by using a solvent dissolving the oligomers contained in the polyester and substantially not dissolving the polyester to remove the oligomers by extraction. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a method for treating a polytrimethylene terephthalate-based polyester, a polyester obtained therefrom, and a polyester fiber. More specifically, the oligomer content in the polyester is reduced, and the amount of regenerated cyclic dimer during melt molding is reduced. The present invention relates to a method for treating a polytrimethylene terephthalate polyester, which has stable performance during melt spinning and has excellent performance in quality control in a dyeing process, and a polyester and polyester fiber obtained therefrom.

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 typified by polyethylene terephthalate.
However, this polytrimethylene terephthalate tends to generate an oligomeric cyclic dimer during polycondensation, but this cyclic dimer adheres as a foreign matter in the vicinity of the spinneret during the spinning process and causes yarn breakage. There is a problem that oligomers are precipitated during weaving and knitting to lower the processing stability.

In order to solve such problems, a polytrimethylene terephthalate resin having an oligomer content of 1% by weight 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 surely be greatly reduced, but the cyclic dimer is regenerated at the time of remelting for melt molding. It has not reached. Further, when the oligomer content is reduced by solid phase polymerization, highly crystallized foreign matter is generated and it is difficult to maintain the quality.
On the other hand, a method of adding a phosphoric acid compound has been proposed as a method for reducing the activity of the catalyst (see Patent Document 2). In this method, a cyclic dimer removing apparatus is used at the same time. 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

  An object of the present invention is to provide a treatment method for reducing the oligomer content in a polytrimethylene terephthalate-based polyester without performing solid-phase polymerization, and to obtain a regenerated cyclic dimer at the time of melt molding obtained by the treatment method Production amount is stable, the process condition at the time of melt spinning is stable, the amount of oligomer precipitation at the time of weaving and knitting is small, and stable fibers can be produced, and the quality control in the dyeing process is excellent. It is to provide a polyester, and also to provide a polyester fiber obtained by melt spinning the polyester.

The present invention comprises treating a polyester having a main repeating unit as a trimethylene terephthalate unit with a solvent that dissolves an oligomer contained in the polyester and does not substantially dissolve the polyester, and extracts and removes the oligomer. The present invention relates to a method for treating polyester.
Here, the solvent is preferably a halogenated hydrocarbon solvent, an aprotic polar solvent and / or an amide solvent.
Next, the present invention relates to a polyester obtained by the above processing method.
Here, the polyester preferably contains an alkaline earth metal and / or alkali metal element amount in the range of 5 to 300 ppm and a phosphorus element amount in the range of 10 to 500 ppm.
As such polyester, the polyester which contains the phosphonate compound represented by following formula (I) in 0.01-0.5 mass% in polyester is mentioned.

[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 or alkaline earth metal atom. When M is an alkali metal, m = 1, and when M is an alkaline earth metal, m = 2. ]
Next, the present invention relates to a polyester fiber having a cyclic dimer content of 2.2% by mass or less obtained by melt spinning the above polyester.

  According to the present invention, there is no generation of highly crystallized foreign matter due to solid phase polymerization, the amount of regenerated cyclic dimer during melt molding is small, the process condition during melt spinning is stable, and quality control in the dyeing process It is possible to provide a polytrimethylene terephthalate-based polyester and a fiber having excellent performance.

Hereinafter, the present invention will be described in more detail.
The polyester used in the present invention is a 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, etc., or ethylene glycol, tetramethylene glycol, diethylene glycol, polyethyleneglycol, 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. Thereafter, any of the polymerization methods may be employed.

The polyester polymerization catalyst used in the present invention is not particularly limited, but a titanium compound is preferably used as the polymerization catalyst. Here, the titanium compound used as a catalyst is preferably an organic titanium compound soluble in a polymer. Although there is no restriction | limiting in particular as content of the said titanium compound, From a polycondensation reactivity, the hue of polyester obtained, and a heat resistant viewpoint, about 2-150 millimol% is contained as a titanium metal element with respect to all the dicarboxylic acid components. It is preferable.
Here, when a method of polymerizing an ester-forming derivative of terephthalic acid after undergoing a transesterification reaction with trimethylene glycol is employed, as a transesterification catalyst, a calcium compound, a magnesium compound, a manganese compound, a zinc compound, etc. You may use together the catalyst used as a transesterification reaction catalyst of polyester. 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 resulting from the catalyst. The titanium compound is not particularly limited, and examples thereof include general titanium compounds as polyester polycondensation catalysts, 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 solvent used in the treatment method of the present invention needs to be a solvent that dissolves the oligomer in the polyester and does not substantially dissolve the polyester. “Polyester is not substantially dissolved” in the present invention means that the mass of the polyester after the solvent treatment of the present invention is 85% by mass or more of the mass of the polyester before the treatment.
The oligomer extraction removal solvent is preferably a halogen hydrocarbon solvent, an aprotic polar solvent and / or an amide solvent.
Here, the halogenated hydrocarbon is a compound in which a hydrogen atom of a hydrocarbon (an organic compound composed only of carbon and hydrogen) is substituted with a halogen atom, and examples of the halogen hydrocarbon solvent include chloroform and dichloromethane. .
On the other hand, an aprotic polar solvent is a solvent that has a remarkably low ability to donate protons and has a larger dipole moment, and an amide solvent is a solvent having an amide group. Examples of the aprotic polar solvent and the amide solvent include N-methylpyrrolidone, dimethylformamide, dimethylacetamide, dimethylsulfoxide and the like.

The treatment method of the present invention may be a method of circulating a solvent at room temperature or under heating, a method of simply immersing a polymer, or any other method.
For example, a polytrimethylene terephthalate-based polyester chip is placed in a processing apparatus containing the solvent used in the present invention, and the temperature is from 5 ° C. to the boiling point of the solvent, preferably from 10 ° C. to the boiling point of the solvent. Examples of the method include drying after 100 hours at a temperature, preferably 3 to 24 hours, and then 100 to 160 ° C., preferably 110 to 140 ° C. for 1 to 6 hours, preferably 1 to 4 hours.

  The amount of cyclic dimer in the polyester obtained by the treatment method of the present invention is preferably 1.7% by mass or less. When the cyclic dimer content is within this range, the process condition in the melt spinning and drawing process of the polyester fiber is less likely to become unstable. The cyclic dimer content is more preferably 1.6% by mass or less.

Here, the “cyclic dimer” is known to be represented by the following structural formula (1). Since the cyclic dimer has a particularly high sublimation property and hot water solubility, it becomes a main causative substance that causes the problem of unstable process conditions in the melt spinning and stretching processes as described above.
_{OCH 2 CH 2 CH 2 OOC-} Ph-CO
| | (1)
_{OC-Ph-COOCH 2 CH 2} CH 2 O

  The polyester obtained by the treatment method of the present invention preferably contains an alkaline earth metal and / or an alkali metal element amount in the range of 5 to 300 ppm and a phosphorus element amount in the range of 10 to 500 ppm. The alkaline earth metal and / or alkali metal element may be derived from the above-described transesterification catalyst, and the phosphorus element may also be derived from a single phosphorus compound. An alkaline earth metal salt and / or an alkali metal salt of an acid compound is preferable. When the amount of the alkaline earth metal and / or alkali metal element is less than 5 ppm and / or the amount of the phosphorus compound is less than 10 ppm, the amount of regenerated cyclic dimer increases, which is not preferable. On the other hand, when the amount of alkaline earth metal and / or alkali metal element exceeds 300 ppm and / or the phosphorus compound exceeds 500 ppm, the heat resistance of the resulting polyester is unfavorable. The amount of alkaline earth metal and / or alkali metal element in the polyester obtained by the treatment method of the present invention is preferably in the range of 10 to 250 ppm, more preferably in the range of 15 to 200 ppm. The amount of phosphorus element is preferably in the range of 15 to 400 ppm, more preferably in the range of 20 to 300 ppm.

The polyester composition obtained by the treatment method of the present invention is a phosphonate compound represented by the above formula (I) in order to satisfy the above-mentioned alkaline earth metal and / or alkali metal element content and phosphorus element content. It is preferable that 0.01-0.5 mass% is contained. Here, when the content of the phosphonate compound is less than 0.01% by mass, the amount of the regenerated cyclic dimer is unfavorably increased. On the other hand, when the content exceeds 0.5% by mass, the resulting polyester has heat resistance. Is unfavorable because of lowering. As for content of the said phosphonate compound, the range of 0.03-0.3 mass% is further more preferable.
Here, “regenerated cyclic dimer” means a cyclic dimer that is regenerated as a thermodynamically stable compound by cleaving the ester bond of a part of the polyester that is linearly connected by repeating units. To do.

Here, in the above formula (I), the hydrocarbon group having 1 to 10 carbon atoms of R ₁ , R ₂ and R ₃ is methyl group, ethyl group, propyl group, isopropyl group, butyl group, tertiary butyl group , A phenyl group, a benzyl group, and the like, preferably a methyl group, an ethyl group, an isopropyl group, and a tertiary butyl group. 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, and the like. 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 phosphonate compound represented by the above formula (I) include 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 (((3,3 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- Droxyphenyl) ethyl) phosphonate), 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) -4-hydroxyphenyl) ethyl) phosphonate) and the like .

  The method for adding the compound represented by the above formula (I) preferably contained in the polyester of the present invention to the polyester is not particularly limited. For example, the compound is added to the polymerization step at an arbitrary stage during polyester polymerization. Method, melt blending the phosphonate compound dissolved or dispersed in the powdered polytrimethylene terephthalate polymer in a solvent using a twin screw extruder, etc., melt blending method in a master batch method, etc. Is mentioned.

  The “production rate of“ recycled cyclic dimer ”” (increased content by mass of the cyclic dimer described above contained in the polyester per minute) was 0.01 mass% / When the amount is larger than 5 minutes, the amount of cyclic dimer regeneration at the time of melt spinning increases, and as a result, the process condition in the spinning process and subsequent weaving and knitting processes may become unstable, which is not preferable. The cyclic dimer formation rate is preferably 0.009% by mass / min or less, and more preferably 0.008% by mass / min or less. In order to reduce the regenerated cyclic dimer formation rate to 0.01% by mass / min or less, it is effective to contain 0.01 to 0.5% by mass of the above-described phosphonate compound in the polyester. .

  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 of the present invention is preferably produced by melt spinning in the range of 240 ° C to 280 ° C, and the melt spinning speed is preferably 400 to 5,000 m / min. When the spinning speed is in 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, in order to enhance the texture of the polyester fiber of the present invention, an alkali weight loss treatment is also preferably performed.

The cyclic dimer content contained in the polyester fiber of the present invention thus obtained is preferably 2.2% by mass or less. When the cyclic dimer content is within this range, dyeing spots or the like are less likely to occur in the polyester fiber dyeing step. The cyclic dimer content is particularly preferably 2.0% by mass or less.
In order to make the content of the cyclic dimer in the polyester fiber 2.2% by mass or less, for example, the content of the phosphonate compound represented by the above formula (I) is 0.01 to 0.5% by mass. Or can be adjusted by the treatment time and treatment temperature with the solvent used in the treatment method of the present invention.

  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 polyester (chip) and polyester fiber of the present invention may contain a small amount of additives as required, such as lubricants, pigments, dyes, antioxidants, solid phase polycondensation accelerators, fluorescent whitening agents, antistatic agents, antibacterial agents. , UV absorbers, light stabilizers, heat stabilizers, shading agents or matting agents may be included. In particular, titanium oxide as a matting agent is preferably added. As the titanium oxide, 0.01 to 10% by mass of titanium oxide having an average particle diameter of 0.01 to 2 μm is finally contained in the obtained polyester. Such addition is preferable.

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 polymer was determined from the viscosity value measured at 35 ° C. in an o-chlorophenol solution.
(2) Measurement of calcium content and phosphorus content in polyester:
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. Chloroform was used as a developing solvent, a sample obtained by dissolving 1 mg of a sample in 1 ml of hexafluoroisopropanol and diluted to 10 ml with chloroform was injected, and the mass percentage in the polymer was determined from a standard cyclic dimer calibration curve.
(4) Quantification of phosphonate compound content in the polyester composition:
After dissolving a polymer sample in deuterated trifluoroacetic acid / deuterated chloroform (volume ratio) = 1/1 mixed solvent, nuclear magnetic field using JEOL AJ-600, superconducting FT-NMR. A resonance spectrum ( ¹ H-NMR) was measured. The phosphonate compound content was 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 L1013.

Reference 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.
Subsequently, the obtained reaction product was transferred to another reactor equipped with a stirrer and a glycol distillation condenser, and gradually heated from 210 ° C. to 265 ° C., while the pressure was reduced from normal pressure to a high vacuum of 70 Pa. A polymerization reaction was performed. While tracing the melt viscosity of the reaction system, the polymerization reaction was terminated when the intrinsic viscosity became 0.74 dL / g.
The molten polymer was extruded into cooling water in a strand form from the bottom of the reactor and cut into chips by using a strand cutter to obtain a polyester chip having a cyclic dimer content of 2.4% by mass.

Example 1
1 kg of the polyester chip obtained in Reference Example 1 was contact-treated for 5 hours in a 10-liter treatment apparatus containing 3 liters of N-methylpyrrolidone at 90 ° C., and then N-methylpyrrolidone was removed by washing with water. C. for 4 hours under a nitrogen stream. The results of the obtained polyester chip are shown in Table 1.

Example 2
In Example 1, the same procedure was performed except that the solvent for contact treatment with the chip was changed to dichloromethane, the treatment temperature was changed to room temperature, and the treatment time was changed to 24 hours. Table 1 shows the results of the obtained chip.

Example 3
In Example 1, it carried out similarly except having changed the solvent contact-processed with a chip | tip to dimethylacetamide. Table 1 shows the results of the obtained chip.

Example 4
In Example 1, the same procedure was performed except that the solvent for contact treatment with the chip was changed to chloroform, the treatment temperature was changed to room temperature, and the treatment time was changed to 24 hours. Table 1 shows the results of the obtained chip.

Example 5
In Example 1, it carried out similarly except having changed the solvent contact-processed with a chip | tip to dimethylformamide. Table 1 shows the results of the obtained chip.

Example 6
In Example 1, it carried out similarly except having changed the solvent which contact-processes with a chip | tip to dimethylsulfoxide, and changed process temperature to 100 degreeC. Table 1 shows the results of the obtained chip.

Example 7
The dried chip in Example 1 was melted at 260 ° C. using an extrusion spinning machine having a spinneret provided with 36 circular spinning holes having a hole diameter of 0.27 mm, a discharge amount of 34 g / min, and a take-up speed of 2400 m / min. To obtain an undrawn yarn. 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 of the obtained fiber are shown in Table 2.

Example 8
The chip dried in Example 1 was remelted at 260 ° C. using a twin-screw extruder, and then calcium diethylbis ((((3,5- (1,1-dimethylethyl) -4-hydroxyphenyl) from the side feeder. ) Methyl) phosphonate) was added while adjusting the content to be 0.1% by mass, and it was cut again using a strand cutter to obtain a polyester chip having an intrinsic viscosity of 0.70 dL / g. The obtained chip was fiberized in the same manner as in Example 7. The results of the obtained fiber are shown in Table 2.

Example 9
In Example 8, it changed to the chip | tip used in Example 2 except having changed into the chip | tip dried in Example 2, and fiberized. The results of the obtained fiber are shown in Table 2.

Example 10
0.5 mass% dichloromethane solution of calcium diethylbis (((3,5- (1,1-dimethylethyl) -4-hydroxyphenyl) methyl) phosphonate) with respect to 100 parts by mass of the chip dried in Example 3 21.2 parts by mass were sprayed uniformly and dried at room temperature in a nitrogen stream. The obtained chip was fiberized in the same manner as in Example 7. The results are shown in Table 2.

Example 11
In Example 10, the same procedure was performed except that the chip used was changed to the dried chip in Example 4, and fiberized. The results of the obtained fiber are shown in Table 2.

Example 12
In Example 10, it changed into the chip | tip used, and changed into the chip | tip dried in Example 5, and it carried out similarly and fiberized. The results of the obtained fiber are shown in Table 2.

Example 13
In Example 8, it changed to the chip | tip used in Example 6 except having changed into the chip | tip dried in Example 6, and was fiberized. The results of the obtained fiber are shown in Table 2.

Comparative Example 1
The same procedure as in Example 1 was performed except that the contact treatment with N-methylpyrrolidone was not performed (chip of Reference Example 1). The results are shown in Table 1.

Comparative Example 2
In Example 7, it carried out similarly except having changed the chip | tip used to the chip | tip (Comparative Example 1 chip | tip) of the comparative example 1. FIG. The results are shown in Table 2.

  As is clear from Tables 1 and 2, the polyester of the present invention had a low cyclic dimer content and a low cyclic dimer content in the fiber after spinning, and was good.

According to the present invention, it is possible to provide a polyester and a fiber that have a small amount of regenerated cyclic dimer at the time of melt molding, have a stable process tone at the time of melt spinning, and have excellent quality control in the dyeing process. it can. In addition, the obtained fiber has normal mechanical properties, and can be sufficiently used for the use of conventionally used polytrimethylene terephthalate fiber.

Claims (7)

  A polyester having a main repeating unit as a trimethylene terephthalate unit is treated with a solvent that dissolves the oligomer contained in the polyester and does not substantially dissolve the polyester, and the oligomer is extracted and removed. Polyester processing method.   The method for treating a polyester according to claim 1, wherein the solvent is a halogenated hydrocarbon solvent.   The method for treating a polyester according to claim 1, wherein the solvent is an aprotic polar solvent and / or an amide solvent.   The polyester obtained by the processing method of any one of Claims 1-3.   The polyester according to claim 4, wherein the polyester contains an alkaline earth metal and / or alkali metal element amount in the range of 5 to 300 ppm and a phosphorus element amount in the range of 10 to 500 ppm. The polyester of Claim 4 or 5 which contains the phosphonate compound represented by following formula (I) as a phosphorus compound in 0.01-0.5 mass% in polyester.
[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 or alkaline earth metal atom. When M is an alkali metal, m = 1, and when M is an alkaline earth metal, m = 2. ] A polyester fiber having a cyclic dimer content of 2.2 mass% or less, obtained by melt spinning the polyester according to any one of claims 4 to 6.