JP2000282325A - Polyester composition for melt spinning, polyester partially orientated undrawn yarn and its production - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain the subject partially orientated undrawn yarn prominently developing an orientation controlling effect, having excellent process passage by adding a fixed amount of a specific diacetal compound to a polyester comprising an ethylene terephthalate as a main repeating unit and subjecting the mixture to melt spinning. SOLUTION: A polyester comprising an ethylene terephthalate as a main repeating unit is formulated with 0.05-0.6 wt.% based on the polestar of a diacetal compound of the formula (R1 and R2 are each H, a 1-4C alkyl, a 1-4C alkoxy, a halogen, nitro or amino; m and n are each 1-5; t is 0 or 1) such as dibenzylidenesorbitol. The obtained polyester composition is subjected to melt spinning at 3,000-6,000 m/minute take-off speed to give the objective polyester partially orientated undrawn yarn having 0.02-0.06 double refractive index.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a polyester composition for melt spinning, a partially oriented undrawn polyester yarn, and a method for producing the same. More specifically, the present invention relates to a polyester composition having excellent yarn-making properties and productivity, a method for producing a polyester partially oriented undrawn yarn, and a polyester partially oriented undrawn yarn having excellent stretchability and process passability.

[0002]

2. Description of the Related Art Polyester fibers such as polyethylene terephthalate are used in large quantities and in a wide range of fields because of their excellent properties. Above all, partially oriented undrawn yarn (hereinafter abbreviated as POY) with a take-up speed of 2000 to 4000 m / min has an advantage that it can be used not only for drawing but also for drawing false twisting as it is. Therefore, it occupies an important industrial position. As for the false twisted yarn, by employing a draw false twisting process in which stretching and false twisting are simultaneously performed using this POY,
Significant improvement in productivity has been achieved as compared with the conventional method of false twisting drawn yarn.

However, as the demand for further improvement in productivity has increased, attempts have been made to increase productivity per unit time by increasing the spinning speed of undrawn yarn. However, in the case of polyester fibers, there is a problem that orientation crystallization proceeds with an increase in spinning speed, and the mechanical properties of the fibers change. For the purpose of solving this problem and obtaining fibers having the same characteristics even when the spinning speed is increased, many means have been studied to suppress the molecular orientation of polyester which increases as the spinning speed increases.

[0004] For example, as disclosed in JP-A-57-11211, a method of blending an anisotropic melt with polyethylene terephthalate, and a method disclosed in JP-A-56-11211.
As disclosed by JP-91013, a method of blending a polymer incompatible with polyester, for example, polystyrene, is known. Although the orientation suppression effect is very large in these methods, unfortunately, there is a problem due to the presence of a heterogeneous polymer, that is, deterioration in fineness unevenness and abnormal dyeing, and furthermore, fluff is likely to occur, and the processability of high-order processing is poor. There were drawbacks such as.

Further, as disclosed in Japanese Patent Application Laid-Open No. 58-144117, a method is known in which another aliphatic polyester is copolymerized with polyethylene terephthalate to suppress oriented crystallization. However, in this case, there is a problem that heat resistance and dyeing fastness are inferior because of containing the aliphatic polyester.

Further, in a process of polymerizing a polyester, a branched structure is formed by copolymerizing a trifunctional carboxylic acid such as trimellitic acid, and a low-oriented fiber is obtained by using this polymer. The method of JP-A-33234 and the method of JP-A-3-19914 using an oxysilicate in a similar manner are also known. However, in these methods, the molecular weight of the polyester increases, and a branched structure develops during the so-called polycondensation process, so that it is difficult to increase the molecular weight of the polyester to a desired value, and gelation occurs. In order to control the polymerization, it was necessary to strictly control the polymerization conditions, and the melt pressure was increased due to an increase in the melt viscosity. .

Further, a method of Japanese Patent Application Laid-Open No. 9-302522 is known in which a low-oriented fiber is obtained by adding a glycidyl ether type bifunctional epoxy compound to polyester. However, even with this method, there is a problem that it is difficult to control the reaction because the reaction between the epoxy compound and the polyester exhibits an orientation suppression effect, and that the reactivity of the epoxy compound is too high to cause gelation.

[0008]

SUMMARY OF THE INVENTION An object of the present invention is to solve the above-mentioned problems of the prior art and to provide a polyester undrawn yarn having a suppressed molecular orientation. That is, to provide a polyester partially oriented undrawn yarn excellent in stretchability and draw false twisting property, and to provide a polyester composition suitable for improving the productivity of the polyester partially oriented undrawn yarn, and further to provide the polyester It is an object of the present invention to provide a method for stably and efficiently producing a partially oriented undrawn yarn without any problem in the process.

[0009]

Means for Solving the Problems The inventors of the present invention have studied diligently to suppress the molecular orientation, which increases with an increase in the spinning speed, and to obtain a polyester partially oriented undrawn yarn having good drawability and draw false twisting properties. Has been repeated. Among them, it has been found that by adding a certain diacetal compound to the polyester, the degree of orientation of the polyester is reduced,
The present invention has been reached.

That is, the present invention is characterized in that a main repeating unit is ethylene terephthalate, and a diacetal compound represented by the following general formula 1 is added at a ratio of 0.05 to 0.6% by weight. A polyester composition for spinning is provided.

[0011]

Embedded image

[0012]

BEST MODE FOR CARRYING OUT THE INVENTION The polyester referred to in the present invention is
It mainly refers to so-called polyethylene terephthalate, which is composed of a terephthalic acid component and an ethylene glycol component.
The components may be copolymerized. Examples of the dicarboxylic acid compound that can be used in place of terephthalic acid include, for example, isophthalic acid, 2,6-naphthalenedicarboxylic acid, diphenyldicarboxylic acid, adipic acid, sebacic acid, 1,4-cyclohexanedicarboxylic acid, and 5-sodium sulfoisophthalic acid , 5-tetrabutylphosphonium isophthalic acid, and other aromatic, aliphatic, and alicyclic dicarboxylic acids and their derivatives. Examples of diol compounds that can be used in place of ethylene glycol include aromatic and aliphatic compounds such as propylene glycol, tetramethylene glycol, 1,4-cyclohexanedimethanol, diethylene glycol, neopentyl glycol, polyalkylene glycol, bisphenol A, and bisphenol S. And alicyclic diol compounds. The polyester of the present invention may contain a small amount of additives such as a matting agent, a flame retardant, and a lubricant.

The polyester composition for melt spinning in the present invention needs to be added with a diacetal compound represented by the following general formula 1.

[0014]

Embedded image As the functional group represented by R ¹ and R ² in the diacetal compound, an alkyl group and an alkoxy group are preferable from the viewpoint of compatibility with the polyester. Examples of the alkyl group include methyl, ethyl, propyl, and butyl groups, and examples of the alkoxy group include methoxy, ethoxy, propoxy, and butoxy groups. Examples of the diacetal compound include the following. Dibenzylidene sorbitol Dibenzylidene xylitol Bis-O- (p-methylbenzylidene) sorbitol Bis-O- (p-methylbenzylidene) xylitol Bis-O- (p-ethylbenzylidene) sorbitol Bis-O- (p-ethylbenzylidene) xylitol Bis-O- (3,4-dimethylbenzylidene) sorbitol The amount of the bis-O- (3,4-dimethylbenzylidene) xylitol diacetal compound needs to be 0.05 to 0.6% by weight based on the polyester. . When the content is less than 0.05% by weight, the alignment suppressing effect is hardly observed. As the addition amount of the diacetal compound increases, the orientation suppressing effect also increases. However, when the addition amount exceeds 0.6% by weight,
The fiber may have high elongation and low strength with respect to the spinning tension because the orientation suppressing effect is too large, or may deteriorate the POY's yarn-making properties such as fluff or breakage of single yarn during spinning.

The polyester composition of the present invention shows a lower degree of orientation when melt-spinning is carried out under the same spinning conditions as compared with a polyester containing no diacetal compound.
Therefore, when drawn at the same spinning speed, the POY formed from the polyester composition of the present invention should have a higher draw ratio during drawing and drawing false twisting than the POY formed from polyester without the addition of a diacetal compound. Can be. That is, the POY fineness required to obtain a drawn polyester yarn and a processed yarn having a desired fineness can be made larger in the POY of the present invention than in the POY containing no diacetal compound, and the POY production amount per unit time can be increased. Can be improved.

In order to obtain the same degree of orientation from the polyester composition of the present invention as the POY formed from the polyester to which the diacetal compound is not added, it is possible to increase the spinning speed of the POY. In this case, the fineness of the POY required to obtain a drawn polyester yarn and a processed yarn having a desired fineness is almost the same for the POY composed of the polyester composition of the present invention and the POY composed of the polyester not added with the diacetal compound. Since the POY of the invention is obtained at a higher spinning speed, the POY productivity per unit time can be further improved.

The polyester composition for melt-spinning to which the diacetal compound of the present invention is added exhibits a lower degree of orientation when taken at the same take-off speed than the conventional polyester without the addition of the diacetal compound. The reason why the degree of orientation of the fiber obtained by adding the compound is suppressed is considered as follows. That is, the diacetal compound used in the present invention has substantially the same three-dimensional structure as the polyethylene terephthalate repeating unit, but has a structure that hinders the freedom of rotation about the covalent bond. By adding a very small amount of such a compound, the benzene ring in the diacetal compound and the benzene ring in the polyethylene terephthalate cause a strong interaction during the flow deformation of the melt spinning, and the degree of freedom of translation and rotation of the polyethylene terephthalate is reduced. It is considered that the molecular orientation is suppressed by the hindrance.

What is important here is that when the diacetal compound of the present invention is used, unlike the conventional additive for suppressing orientation, the polyester and the diacetal compound hardly cause a chemical bond. Therefore, the intrinsic viscosity (IV value) and the terminal carboxyl group amount (COOH) of the polyester spun yarn hardly change, and so-called “crosslinking”, which is a branch accompanied by a chemical bond, is not formed or even if it is formed. It is considered very slight. Furthermore, in the present invention, since the diacetal compound is added for the purpose of interacting with the polyester, there is a large orientation suppression effect with a very small addition amount, and the diacetal compound is a low molecular weight compound and has a very high affinity with the polyester. No problems such as yarn breakage during spinning and drawing and spotting caused by addition of a different high molecular weight material such as when an anisotropic melt or an incompatible polymer are added occur at all.

Since the POY formed from the polyester composition of the present invention has an orientation-suppressing effect, it has various good properties when it is subjected to stretching or stretch false twisting, and the POY production per unit time is reduced. In addition to the advantage of being able to be made larger, it also has favorable characteristics such as improved processability in drawing and drawing false twisting and higher crimping characteristics when used as a processed yarn.

The partially oriented polyester unstretched yarn of the present invention has a birefringence index of 0.02 to 2, which is an index indicating the degree of molecular orientation.
It is preferably 0.06. Birefringence 0.02-
When it is 0.06, an appropriate heating temperature and stretching ratio can be obtained in the stretch false twisting process, and stable working can be performed.

The polyester partially oriented undrawn yarn of the present invention comprises a polyester having ethylene terephthalate as a main repeating unit and a diacetal compound represented by the general formula 1 in a proportion of 0.05 to 0.6% by weight based on the polyester. And melt-spinning the obtained polyester composition at a take-up speed of 3000 to 6000 m / min.

The addition of the diacetal compound can be carried out during the polycondensation reaction of the polyester or at any stage after the reaction. The diacetal compound used in the present invention is a low-molecular-weight organic compound, has good dispersibility in ethylene glycol and polyester, and does not require the use of a special dispersion medium. A homogeneous polyester mixture is obtained without volatilization.

The polyester resin and the diacetal compound formed into chips may be melt-kneaded or dry-blended before spinning. Also in this case, since the dispersibility of the diacetal compound is good, a homogeneous polyester mixture can be obtained in a short time. Further, a master chip containing a high concentration of a diacetal compound may be separately prepared, and may be added during melt spinning.

The polyester fiber obtained by any of these methods is homogeneous, and does not cause problems such as unevenness of fineness or staining of a single yarn caused by addition and mixing.

By using the polyester composition of the present invention, the effect of suppressing the orientation is remarkably exhibited when melt spinning, particularly, melt spinning of POY, and a high spinning speed and / or draw ratio can be obtained. POY per hour
Production volume can be increased. Further, the POY formed from the polyester composition of the present invention has preferable characteristics such as improved processability during drawing and false twisting, and higher crimping characteristics when used as a processed yarn. Since these useful properties can be obtained by a simple method of adding a specific amount of a diacetal compound and spinning, the present invention is considered to be very significant from an industrial viewpoint.

Hereinafter, the present invention will be specifically and more specifically described with reference to Examples. However, the present invention is not limited to the following examples. The physical properties in the examples were measured by the following methods.

[0027]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Intrinsic viscosity (IV) Measured in orthochlorophenol at 25 ° C.

B. Terminal carboxyl group content (COO
H) 0.5 g polyester sample was dissolved in 10 ml orthocresol and determined by neutralization titration using KOH. Units are expressed as equivalents of carboxyl groups per polyester 10 ⁶ g.

C. Strong elongation The tensile strength was measured using an Orientec Tensilon tensile tester at an initial sample length of 50 mm and a tensile speed of 400 mm / min.

D. Birefringence (ΔN) Using a BH-2 polarizing microscope compensator manufactured by OLYMPUS, the birefringence was determined from the retardation and the fiber diameter by a normal interference fringe method.

E. Fineness spot (U%) Using a Worcester spot tester manufactured by Chelbegar Worcester,
Yarn speed 100m / min, measured with measurement type normal, U%
The value was determined.

F. Crimp characteristics (CR) of the processed yarn The fiber is wrapped in a 10-turn scallop shape, 90 ° C, 20
Perform warm water treatment for 1 minute. After air drying overnight, apply an initial load of 0.04 times the denier of the fiber and an actual load of 2.0 times the denier of the fiber in water at 20 ° C, and measure the length of the case after 2 minutes. (L1). Immediately remove the actual load 2
After a minute, the length is measured again (L2). Based on L1 and L2 obtained in this manner, {(L1-L2) / L1} ×
100 was taken as the CR value.

G. Using a fly counter manufactured by Toray Co., Ltd.
Under the conditions of 0 m / min and measurement sensitivity of 0.1, measurement for 50 minutes was 1
Performed 0 times, the average value of the counted fluff number 10 ⁴
The number of fluff per m was used. Example 1 A normal esterification reaction was performed using terephthalic acid and ethylene glycol to obtain a bis- (β-hydroxyethyl) terephthalate low polymer, and then bis-O- (p-methylbenzylidene) sorbitol dispersed in ethylene glycol Was added to terephthalic acid to carry out a polycondensation reaction to obtain a polyester composition. The IV of this polymer is shown in Table 1. The COOH of this polymer is 15.9 eq.
/ Ton, suggesting that bis-O- (p-methylbenzylidene) sorbitol is not substantially reacted with the polyester.

This was taken out from a spinneret having a hole diameter of 0.23 mmφ and 36 holes at a spinning temperature of 295 ° C. and a spinning speed of 60.0 g / min and a spinning speed of 4000 m / min using a uniaxial extruder to obtain a polyester POY. . No yarn breakage occurred during spinning, and the spinning properties were excellent. Table 1 shows the fineness, elongation, and Δn of this POY. Δn is smaller than POY obtained at the same spinning speed as 37 × 10 ^−3, and the orientation during spinning is suppressed by the addition of bis-O- (p-methylbenzylidene) sorbitol. I understand.

The POY was processed at a processing speed of 450 m / min and a processing temperature of 2 using a friction disk type draw false twisting machine.
Stretching false twisting (hereinafter referred to as DTY processing) was performed at 10 ° C. No thread breakage during processing, excellent workability,
Fluff was also very small and 0.2 U / 10 ⁴ m. Table 1 shows the fineness and CR of the processed yarn. CR is 50
%, Which indicates that it has excellent crimp characteristics.

As can be seen from Table 1, in obtaining a 75 denier textured yarn, the polyester composition containing bis-O- (p-methylbenzylidene) sorbitol was used to increase the orientation even when the spinning speed of POY was increased. Is suppressed, the DTY processing magnification can be increased, and P
It can be seen that, in addition to being able to greatly improve the OY productivity (increase in the POY discharge amount), the obtained POY has excellent workability and, when processed yarn is used, has excellent crimp characteristics. . Comparative Example 1 A normal esterification reaction was carried out using terephthalic acid and ethylene glycol to obtain bis-
A (β-hydroxyethyl) terephthalate low polymer was obtained, and then a polycondensation reaction was performed to obtain polyethylene terephthalate. The IV of the polymer is shown in Table 1. Also polymer C
OOH was 16.2 eq / ton.

At a discharge rate of 46.5 g / min and a spinning speed of 3
Spinning was performed in the same manner as in Example 1 except that the speed was set at 000 m / min, to obtain polyethylene terephthalate POY. Although the yarn breakage occurred once, the yarn-making properties were generally good.
Table 1 shows the fineness, elongation, and Δn of this POY.

This POY is converted into a DT in the same manner as in the first embodiment.
Y processing was performed. Although thread breakage occurred at the start of processing, workability was generally good. The fluff of the obtained processed yarn was 0.7 threads / 10 ⁴ m. Fineness of this processed yarn, C
R is shown in Table 1. The CR is 44%, which indicates that the processed yarn has sufficient crimp characteristics.

As can be seen from Table 1, when ordinary polyethylene terephthalate is used to obtain a 75 denier processed yarn, the obtained POY has sufficient yarn formability, workability, and quality of the processed yarn. In comparison, it can be seen that the POY productivity is extremely reduced (the POY discharge amount is reduced). Comparative Example 2 Using the polyethylene terephthalate polymerized in Comparative Example 1, the discharge rate was 46.7 g / min, and the spinning speed was 4000 m / min.
The spinning was carried out in the same manner as in Comparative Example 1 except that the amount was changed to minutes to obtain polyethylene terephthalate POY. Thread breakage occurred several times during spinning, and the spinnability was inferior to Comparative Example 1. Table 1 shows the fineness, elongation, and Δn of this POY. Δn increases to 65 × 10 ^{−3 as the} spinning speed increases.

This POY was converted to DT in the same manner as in Comparative Example 1.
Y processing was performed. Again, several breaks occurred during processing, and the workability was inferior to Comparative Example 1. Also, the fluff was increased to 1.3 pieces / 10 ⁴ m. Table 1 shows the fineness and CR of the processed yarn. The CR is 38%, which indicates that the processed yarn has only a somewhat insufficient crimp property.

As can be seen from Table 1, increasing the spinning speed of POY using ordinary polyethylene terephthalate to obtain 75 denier processed yarn hardly improves POY productivity, and the obtained processed yarn is crimped. It turns out that the characteristics are poor and the quality is inferior. Example 2 A polyester composition was obtained by polymerization in the same manner as in Example 1, except that the amount of bis-O- (p-methylbenzylidene) sorbitol was 0.05%. The IV of this polymer is shown in Table 1.

This was spun in the same manner as in Example 1 except that the discharge rate was 50.3 g / min and the spinning speed was 3000 m / min, to obtain a polyester POY. No yarn breakage occurred during spinning, and the spinning properties were excellent. Table 1 shows the fineness, elongation, and Δn of this POY. Δn is smaller than POY (Comparative Example 1) obtained at the same spinning speed as 32 × 10 ^−3, and even when the addition amount of bis-O- (p-methylbenzylidene) sorbitol is 0.05%. It can be seen that the orientation during spinning is suppressed.

This POY is converted into a DT in the same manner as in the first embodiment.
Y processing was performed. No thread breakage occurred during processing, and the workability was excellent, and the fluff was as small as 0.3 threads / 10 ⁴ m. Table 1 shows the fineness and CR of the processed yarn. The CR is 46%, which indicates that it has excellent crimp characteristics.

As can be seen from Table 1, when obtaining a denier of 75 denier, even if the spinning speed of POY is the same even with the polyester composition containing 0.05% of bis-O- (p-methylbenzylidene) sorbitol, In addition to the fact that the orientation is suppressed, the DTY processing magnification can be further increased and the POY productivity can be improved (the POY discharge amount can be increased). It can be seen that the yarn has excellent crimp characteristics when used as a yarn. Example 3 A polyester composition was obtained by polymerization in the same manner as in Example 1 except that the amount of bis-O- (p-methylbenzylidene) sorbitol was changed to 0.6%. I of this polymer
V is shown in Table 1.

This was spun in the same manner as in Example 1 except that the discharge rate was 80.0 g / min and the spinning speed was 6000 m / min, to obtain a polyester POY. Although yarn breakage occurred once during spinning, the spinning properties were generally good. Table 1 shows the fineness, elongation, and Δn of this POY. Δn is 45 ×
10 ^-3 and bis-O- (p-methylbenzylidene)
By increasing the amount of sorbitol added to 0.6%, the orientation during spinning is suppressed, and even at a spinning speed of 6000 m / min, D
It can be seen that POY that can be used for TY processing is obtained.

This POY is converted into a DT in the same manner as in the first embodiment.
Y processing was performed. Although thread breakage occurred once during processing, the workability was generally good, and the fluff was 0.2 threads / 10 ^4.
m. Table 1 shows the fineness and CR of the processed yarn. The CR is 46%, which indicates that it has excellent crimp characteristics.

As can be seen from Table 1, when obtaining a processed yarn of 75 denier, a polyester composition having an added amount of bis-O- (p-methylbenzylidene) sorbitol of 0.6% was used to obtain ordinary polyethylene terephthalate. POY that can be used for DTY processing cannot be obtained. POY that can perform normal DTY processing even at a spinning speed is obtained.
It can be seen that POY productivity can be significantly improved (POY discharge amount can be increased), and that the obtained POY has excellent crimp characteristics when processed yarn is used. Comparative Example 3 A polyester composition was obtained by polymerization in the same manner as in Example 1, except that the amount of bis-O- (p-methylbenzylidene) sorbitol was changed to 1.0%. I of this polymer
V is shown in Table 1.

This was spun in the same manner as in Example 1 except that the discharge rate was changed to 106.7 g / min.
OY was obtained. Many yarn breaks occurred during spinning, and the spinning properties were poor. Table 1 shows the fineness, elongation, and Δn of the obtained POY. Δn is 13 × 10 ⁻³ , which indicates that the effect of suppressing the orientation during spinning is increased by increasing the amount of bis-O- (p-methylbenzylidene) sorbitol to 1.0%.

This POY is converted into a DT in the same manner as in the first embodiment.
Y processing was performed, but yarn breakage occurred frequently during processing, and no processed yarn was obtained.

When the amount of bis-O- (p-methylbenzylidene) sorbitol is increased to 1.0%, the effect of suppressing the orientation during spinning is increased, but the spinning and processability may be deteriorated. I understand.

[0051]

[Table 1] Example 4 Bis-dispersed in ethylene glycol during the polycondensation reaction
A polyester composition was obtained by polymerizing in the same manner as in Example 1 except that O- (3,4-dimethylbenzylidene) sorbitol was added in an amount of 0.2% based on terephthalic acid. The IV of this polymer is shown in Table 2.

This was spun in the same manner as in Example 1 except that the discharge rate was changed to 55.3 g / min.
Y was obtained. No yarn breakage occurred during spinning, and the spinnability was as excellent as in Example 1. The fineness and elongation of this POY, Δn
Are shown in Table 2. Δn is smaller than POY (Comparative Example 2) obtained at the same spinning speed as 41 × 10 ⁻³ ,
It can be seen that the orientation during spinning was suppressed by the addition of bis-O- (3,4-dimethylbenzylidene) sorbitol.

This POY is converted into a DT in the same manner as in the first embodiment.
Y processing was performed. No thread breakage occurred during processing, the workability was as excellent as in Example 1, and the fluff was 0.2 threads / 10 ⁴
m. Table 2 shows the fineness and CR of this processed yarn. C
R is 48%, which is larger than that of Comparative Example 1, and it can be seen that R has more excellent crimp characteristics.

As can be seen from Table 2, the orientation is suppressed during spinning by adding bis-O- (3,4-dimethylbenzylidene) sorbitol in obtaining a 75 denier processed yarn, and the spinning speed of POY is increased. In addition to this, the DTY processing magnification can be increased, and POY productivity can be greatly improved (POY discharge amount can be increased). It can be seen that it has a characteristic of being excellent in shrinkage characteristics. Comparative Example 4 A polyester composition was obtained by polymerization in the same manner as in Example 1 except that 0.3% of trimethyl trimellitate was added to terephthalic acid during the polycondensation reaction. The IV of this polymer is shown in Table 2. IV was almost equivalent to that of Example 1, but the COOH of this polymer was 11.4 eq / ton, and Comparative Example 1
And it is smaller than that of Example 1, suggesting that a cross-linking component is generated.

This was spun in the same manner as in Example 1 except that the discharge rate was changed to 56.0 g / min.
Y was obtained. Thread breakage occurred several times during spinning, and the spinnability was poor. Table 2 shows the fineness, elongation, and Δn of this POY.
Δn is the POY obtained at the same spinning speed as 40 × 10 ^−3.
It is smaller than (Comparative Example 2), and it can be seen that the orientation during spinning is also suppressed by the addition of trimethyl trimellitate.

This POY is converted into a DT in the same manner as in the first embodiment.
Was subjected to Y processing, yarn breakage frequently workability during processing is poor, it was very often the fluff also 2.2 U / 10 ⁴ m. Table 2 shows the fineness and CR of this processed yarn. CR is 3
8%, which indicates that the processed yarn has insufficient crimp characteristics.

As can be seen from Table 2, when a 75 denier processed yarn is obtained, the orientation during spinning is also suppressed by the addition of trimethyl trimellitate, and the DTY processing magnification can be increased even when the spinning speed of POY is increased. Yes, P
Although it is possible to greatly improve the OY productivity (increase the POY discharge amount), the spinning and processability of the polyester composition to which trimethyl trimellitate is added deteriorates, and the crimping characteristics of the processed yarn are also reduced. It turns out that it is inferior.

[0058]

[Table 2] Comparative Example 5 Using the polyethylene terephthalate polymerized in Example 3, the discharge rate was 81.7 g / min, and the spinning speed was 7000 m / min.
The spinning was carried out in the same manner as in Example 1 except that the amount was changed to minutes to obtain a polyester POY. Thread breaks occur several times during spinning,
The spinnability was poor. Table 3 shows the fineness, elongation, and Δn of this POY. Δn is 62 × 10 ^-3 and the spinning speed is 70
It can be seen that the POY obtained at a speed of 00 m / min cannot provide an appropriate processing temperature and stretching ratio.

This POY is converted into a DT in the same manner as in the first embodiment.
Y processing was performed, but yarn breakage occurred frequently during processing, and no processed yarn was obtained.

By setting the amount of bis-O- (p-methylbenzylidene) sorbitol to 0.6% as described above, POY which can be used for DTY processing is large although the effect of suppressing orientation at a spinning speed of 7000 m / min is large. Is not obtained. Example 5 Example 1 was repeated except that the polyester composition polymerized in Comparative Example 3 and the polyethylene terephthalate polymerized in Comparative Example 1 were chip-blended at a ratio of 1: 3, and the discharge rate was 62.7 g / min. Spinning was performed in the same manner as described above to obtain a polyester POY. No yarn breakage occurred during spinning, and the spinnability was excellent as in Example 1. The fineness of this POY,
Table 3 shows the elongation and Δn. Δn is smaller than POY (Comparative Example 2) obtained at the same spinning speed as 31 × 10 ^−3, and the amount of bis-O- (p-methylbenzylidene) sorbitol added by chip blending is 0. Since it is 25%, it can be seen that the orientation during spinning is suppressed.

This POY is converted into a DT in the same manner as in the first embodiment.
Y processing was performed. Although thread breakage occurred once during processing, the workability was generally good, and the fluff was 0.4 threads / 10 ^4.
m. Table 3 shows the fineness and CR of this processed yarn. CR is 49%, which indicates that the material has excellent crimp characteristics.

As can be seen from Table 3, to obtain 75 denier processed yarn, a polyester composition containing 1.0% of bis-O- (p-methylbenzylidene) sorbitol and polyethylene terephthalate were chip-blended.
Even when a polyester mixture in which the amount of bis-O- (p-methylbenzylidene) sorbitol is 0.25% based on the total amount is used, the orientation is suppressed, and the POY productivity is improved (POY
It can be seen that, in addition to making it possible to increase the Y discharge amount, the obtained POY has excellent workability and, when used as a processed yarn, has excellent crimp characteristics.

[0063]

[Table 3]

[0064]

As described above, the use of the polyester composition of the present invention remarkably exerts the effect of suppressing the orientation during melt spinning, in particular, melt spinning of POY, and can increase the spinning speed and / or the draw ratio. , PO per unit time
Y production can be increased. Further, the POY formed from the polyester composition of the present invention has preferable characteristics such as improved processability during drawing and false twisting, and higher crimping characteristics when used as a processed yarn. Further, the POY formed from the polyester composition of the present invention can be obtained by a simple method of adding a specific amount of a diacetal compound and spinning, and also improves the spinnability.

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Claims (4)

[Claims] 1. A polyester for melt spinning, wherein a main repeating unit is ethylene terephthalate, and a diacetal compound represented by the following general formula 1 is added at a ratio of 0.05 to 0.6% by weight. Composition. Embedded image 2. A polyester partially oriented undrawn yarn formed from the polyester composition according to claim 1. 3. The partially oriented undrawn polyester yarn according to claim 2, wherein the birefringence is 0.02 to 0.06. 4. A polyester having ethylene terephthalate as a main repeating unit, wherein a diacetal compound represented by the following general formula 1 is added to the polyester in an amount of from 0.05 to 0.05:
A method for producing a polyester partially oriented unstretched yarn, characterized by adding at a ratio of 0.6% by weight and melt-spinning the obtained polyester composition at a take-up speed of 3000 to 6000 m / min. Embedded image