JPH0967715A - Copolyester fiber - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a copolyester fiber for use in rubber reinforcement, etc., excellent in high initial modulus, low heat shrinkage, and thermal, dimensional stability based on its low creep at high temperatures, from a copolymer composed of terephthalic acid unit, ethylene glycol unit and specific amino group- contg. compound unit(s). SOLUTION: The objective copolyester fiber with an initial modulus of >=12×10<5> g/mm<2> , dry heat shrinkage at 177 deg.C of <=8.0% and creep displacement (at 100 deg.C, under <=1g/d load) of <=0.5% is obtained by fiber formation of a copolymer consisting of (A) terephthalic acid, (B) ethylene glycol, and (C) a compound of the formula H2 N-A<1> -CO2 R<1> and/or the formula H2 N-A<2> -CONHCH2 - CO2 R<2> (A<1> and A<2> are each a 6-12C aromatic hydrocarbon group; R<1> and R<2> are each H or a 1-3C alkyl).

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a polyester-based copolymer fiber having excellent thermal dimensional stability, which fiber is used for reinforcing fiber cords of various rubber products and various industrial products.

[0002]

2. Description of the Related Art Synthetic fibers used for rubber-reinforcing fiber cords are generally required to have fiber physical properties excellent in thermal dimensional stability as well as mechanical stability based on low heat shrinkage, strength and high elastic modulus. Nylon fibers, polyester fibers, aramid fibers and the like are currently used in order to meet the required physical properties and performances.

Of these, polyester fibers are used as various industrial materials including tire cords because of their excellent physical properties and performances. Among the polyester fibers, polyethylene terephthalate fibers are used in a large amount because they have excellent fiber properties and performances and the raw materials are inexpensive.

However, in recent years, in addition to the low heat shrinkage and high elastic modulus, low creep property under high temperature, and a high level of thermal dimensional stability performance based on these physical properties are further required.

As a method of adjusting the elastic modulus and the thermal shrinkage,
Specifically, taking polyethylene terephthalate fiber as an example, it is common to increase the draw ratio of the fiber or perform relaxation treatment after drawing. However, even if the draw ratio of the fiber is efficiently increased, the elastic modulus is increased, but the heat shrinkage is increased, and the target low heat shrinkage cannot be achieved. Further, when the relaxation treatment is performed after the stretching, the high elastic modulus cannot be maintained although it is in the direction of low thermal shrinkage. Furthermore, even if a low thermal shrinkage ratio is achieved by increasing the spinning tension using the recent high-speed spinning technology, the high elastic modulus has not yet been achieved. Further, as a method of adjusting the creep property, since the intermolecular interaction of polyethylene terephthalate itself is extremely low, a method of increasing the molecular weight of the polymer constituting the fiber and increasing the entanglement density of the molecular chains is taken. In the case of melt spinning, even if the molecular weight of the raw material is increased, the molecular chain is broken by the heat and shear during spinning, and although the molecular weight of the polymer constituting the fiber is increased to some extent, a significant improvement in low creep property is achieved. However, it is more difficult to improve the low creep property at high temperature. As described above, the conventional polyethylene terephthalate fiber cannot simultaneously satisfy the low heat shrinkage ratio, the high elastic modulus, and the low creep property at high temperature, and thus it is difficult to achieve a high level of thermal dimensional stability.

In recent years, polyethylene naphthalate fibers having a high elastic modulus and a low heat shrinkage ratio relative to polyethylene terephthalate fibers have attracted attention and have been developed over a wide range. However, regarding the creep characteristics at high temperature,
It is difficult to achieve heat-resistant and low creep property because it is significantly stretched as compared with polyethylene terephthalate fiber.

As described above, the polyester fiber cannot satisfy the high elastic modulus, the low heat shrinkage and the low creep property at a high temperature at the same time, so that a fiber excellent in thermal dimensional stability has not been obtained.

[0008]

SUMMARY OF THE INVENTION The object of the present invention is to maintain a well-balanced and excellent fiber property of conventional polyester such as polyethylene terephthalate fiber, and also to have a high initial elastic modulus, a low heat shrinkage ratio, and a low creep at high temperature. Based on gender,
It is an object of the present invention to provide an economical and practical polyester-based copolymer fiber having excellent thermal dimensional stability.

[0009]

[Means for Solving the Problems] In order to solve the above problems, the present inventors have made diligent studies by paying attention to the composition and molecular weight of a polyester copolymer, the higher order structure of the obtained fiber and its physical properties. As a result, they have found that the objects can be achieved by the following means, and completed the present invention. (1) The polyester-based copolymer fiber of the present invention comprises a copolymer obtained from terephthalic acid, ethylene glycol, at least one of the amino group-containing compounds represented by the following general formula (I) or (II), and And the initial elastic modulus is 12
× 10 ⁵ g / mm ² or more, dry heat shrinkage at 177 ° C. is 8.0% or less, and 1 at 100 ° C.
The creep displacement amount under g / d load is 0.5% or less. General formula _{(I) H 2 N-A} 1 -COOR 1 formula _{(II) H 2 N-A} 2 -CONH-CH 2 -CO
OR ² (In the formula, A ¹ and A ² represent an aromatic hydrocarbon group having 6 to 12 carbon atoms and may be the same or different.
¹ and R ² represent a hydrogen atom or an alkyl group having 1 to 3 carbon atoms, and may be the same or different. (2) In the polyester-based copolymer fiber of the present invention, the weight average molecular weight of the copolymer is 1 in the above (1).
It is characterized in that it is 0 × 10 ⁴ or more. (3) In the polyester-based copolymer fiber of the present invention, in the item (1), the amino group-containing compound is p-aminobenzoic acid, m-aminobenzoic acid, methyl p-aminobenzoate, or m-amino. Methyl benzoate, ethyl p-aminobenzoate, ethyl m-aminobenzoate, p-aminohippuric acid, m-aminohippuric acid, methyl p-aminohippurate, m
-Amino methyl hippurate, ethyl p-amino hippurate, m-
It is characterized in that it is at least one compound selected from the group consisting of ethyl aminohippurate. (4) In the polyester-based copolymer fiber of the present invention, in the item (1), the content of the amino group-containing compound unit in the copolymer is 0.5 with respect to the terephthalic acid unit in the copolymer. It is characterized by being ˜30 mol%. (5) In the polyester-based copolymer fiber of the present invention, in the item (1), the content of the amino group-containing compound unit in the copolymer is 0.5 with respect to the terephthalic acid unit in the copolymer. Is about 20 mol%. (6) In the polyester copolymer fiber of the present invention, the initial elastic modulus is 12 × 10 ⁵ g / in the above (1).
mm ² or more. (7) The polyester-based copolymer fiber of the present invention is characterized in that, in the above item (1), the dry heat shrinkage ratio at 177 ° C. is 8.0% or less. (8) The polyester-based copolymer fiber of the present invention has the above (1)
In the item, the creep displacement amount under a load of 1 g / d at 100 ° C. is 0.5% or less.

Dry heat shrinkage (hereinafter, simply referred to as heat shrinkage)
As used later, means the heat shrinkage ratio measured in a dry atmosphere. The creep displacement amount (hereinafter, referred to as creep property) means a displacement amount that creeps as described later.

The polyester-based copolymer fiber of the present invention is
The molecular structure of the copolymer is different from conventional polyester polymer fibers in that it contains an amino group-containing compound unit as the third component and has a high level of thermal dimensional stability.

In the amino group-containing compound represented by the general formula (I) or (II) used in the present invention, A ¹ and A ² represent an aromatic hydrocarbon group having 6 to 12 carbon atoms,
It may have a substituent. Examples of the aromatic hydrocarbon group include a phenylene group, a naphthylene group, and a biphenylene group. Among them, the phenylene group is preferable from the viewpoint that a fiber having excellent performance can be easily obtained. Further, in this amino group-containing compound, R ¹ and R ² represent a hydrogen atom or an alkyl group having 1 to 3 carbon atoms. When the alkyl group has 4 or more carbon atoms, the molecular weight of the monofunctional by-product (eg, pentanol) produced after the reaction is large,
Since the boiling point becomes high, it becomes difficult to remove the by-product from the reaction system, which hinders the polymerization reaction, which is not preferable. Examples of the alkyl group having 1 to 3 carbon atoms include a methyl group, an ethyl group, an n-propyl group and an isopropyl group, and among them, a methyl group and an ethyl group are preferable.

These amino group-containing compounds can be used alone or as a mixture of two or more kinds.

Examples of the amino group-containing compound represented by the general formula (I) include p-aminobenzoic acid, m-aminobenzoic acid, amino-1-naphthoic acid, amino-2-naphthoic acid and p-aminobenzoic acid. Methyl acid, methyl m-aminobenzoate, ethyl p-aminobenzoate, ethyl m-aminobenzoate, propyl p-aminobenzoate, propyl m-aminobenzoate, methyl amino-1-naphthoate, amino-1- Examples thereof include ethyl naphthoate, methyl amino-2-naphthoate and ethyl amino-2-naphthoate.

The amino-containing compound represented by the general formula (II) includes p-aminohippuric acid, m-aminohippuric acid and p-aminohippuric acid.
Amino methyl hippurate, m-amino methyl hippurate, ethyl p-amino hippurate, ethyl m-amino hippurate, propyl p-amino hippurate, propyl m-amino hippurate, isopropyl p-amino hippurate, m-amino Examples include isopropyl hippurate and the like.

Among these amino group-containing compounds, p-
Aminobenzoic acid, m-aminobenzoic acid, methyl p-aminobenzoate, methyl m-aminobenzoate, ethyl p-aminobenzoate, ethyl m-aminobenzoate, p-aminohippuric acid, m-aminohippuric acid, methyl p-aminohippurate,
m-amino methyl hippurate, p-amino ethyl hippurate, m
-At least one compound selected from the group consisting of ethyl aminohippurate is preferably used. Among these, p-
Ethyl aminobenzoate, p-aminohippuric acid, methyl p-aminobenzoate, and the like are more preferable.

The copolymer used in the present invention is composed of a terephthalic acid unit, an ethylene glycol unit and an amino group-containing compound unit, and the composition distribution of each unit may be a random structure, a block structure or a mixed structure thereof. However, the content of the amino group-containing compound unit in this copolymer is preferably 0.5 to 30 with respect to the terephthalic acid unit.
Mol%, and more preferably 0.5 to 20 mol%.
When this content is less than 0.5 mol%, no superiority to conventional polyethylene terephthalate fibers is recognized, and when it exceeds 30 mol%, the crystallinity of the copolymer is remarkably reduced, and a fiber having a high level of thermal dimensional stability. Can't get

Regarding the molecular weight of the copolymer in the present invention, in order to obtain a high level of thermal dimensional stability of the fiber, the weight average molecular weight is preferably 10 × 10 ⁴ or more, and 11 × 1.
It is more preferably 0 ⁴ or more.

The polyester copolymer fiber of the present invention is
The initial elastic modulus is 12 × 10^Fiveg / mm²Is over,
From the viewpoint of rubber-reinforcing fiber, it is preferably 13 × 10.^Fiveg /
mm ²That is all. Elasticity is 12 × 10^Fiveg / mm²Not yet
When it is full, it is not preferable in terms of rigidity of various rubber products.

The polyester copolymer fiber of the present invention is
The heat shrinkage rate at 177 ° C. is 8.0% or less, and preferably 7.5 in terms of molding when used for various products.
% Or less. When the heat shrinkage rate exceeds 8.0%, it is not preferable in terms of dimensional stability of various products.

The polyester-based copolymer fiber of the present invention is 1
The creep displacement amount under a load of 1 g / d at 00 ° C. is 0.5% or less, and preferably 0.4% or less from the viewpoints of molding into various products and long-term use of the products. If the amount of creep displacement exceeds 0.5%, it is not preferable in terms of finished dimensions of various products.

Due to its excellent performance, the polyester-based copolymer fiber of the present invention has a fiber net for reinforcing rubber products such as tires, V-belts and conveyor belts, fishing nets, nets,
It is useful as a material for various industries such as films, and is particularly preferably used for fiber cords for tires.

The method for producing the polyester-based copolymer fiber of the present invention is not particularly limited as long as the copolymer used contains the above-mentioned molecular structural unit and the fiber satisfies the above-mentioned physical characteristics. An example is shown.

First, an example of a method for producing a copolymer will be described. Predetermined amounts of terephthalic acid, ethylene glycol, an amino group-containing compound, and a catalyst are mixed, and the reaction is performed under a pressure of an inert gas at a predetermined temperature and a predetermined time. Water and by-products are removed from the reaction system, and the mixture is subjected to predetermined pressure reduction, temperature,
The polycondensation reaction is carried out for a certain period of time, followed by quenching. Here, a precursor polyester-based copolymer (which means a copolymer at an intermediate stage in obtaining the copolymer used in the present invention) is obtained.

This precursor polyester copolymer is cut into pellets, and the pellets are crystallized and dried by stirring under reduced pressure at a predetermined temperature for a predetermined time. Further, solid phase polymerization is carried out for a predetermined time while stirring at a temperature not higher than the melting point of the copolymer to obtain the copolymer used in the present invention. In this way, the desired copolymer is optionally obtained in a short time.

Next, an example of a fiber manufacturing method will be described. After the copolymer obtained as described above is melted, it is spun from a nozzle and passed through a heating zone immediately below the nozzle to be cooled and solidified under the control of cooling air temperature and cooling air velocity. The polyester-based copolymer fiber of the present invention can be obtained by subjecting the polyester-based copolymer fiber of the present invention to a heat treatment at a predetermined temperature without relaxing after being wound up or directly drawn at a predetermined temperature and a draw ratio.

The physical properties of the polyester copolymer fiber of the present invention such as high elastic modulus, low heat shrinkage ratio and low creep property at high temperature are as follows as a result of detailed examination of the relationship between the molecular structure and the higher order structure of the fiber. It is the first time that numerical values can be set based on new knowledge.

The elastic modulus, heat shrinkage and creep phenomena of synthetic fibers depend on the interrelationship of crystalline and amorphous regions in the fiber. The index indicating the crystalline state includes crystallinity, crystal size, crystal orientation, and the like, and the index indicating the amorphous state includes amorphous orientation, entanglement of molecular chains, intermolecular interaction, and the like. To be

From these facts, focusing on the state of the amorphous region, as a result of the structural analysis by X-ray and NMR, the copolymer of terephthalic acid, ethylene glycol and the amino group-containing compound used in the present invention is The crystal itself is composed of polyethylene terephthalate itself,
In the amorphous region, the amino group-containing compound forms an amide bond in a region other than the crystalline region of polyethylene terephthalate, mainly between the terephthalic acid unit and the ethylene glycol unit by a dehydration polycondensation reaction, and It was found to be a rigid segment.

From these facts, the polyethylene terephthalate crystal plays the role in the physical properties and performance development of the copolymer fiber of the present invention in the crystalline region, and in the amorphous region, a rigid amide bond is formed by dehydration polycondensation reaction. The presence of such a segment in the main chain of the molecule increases the rigidity of the amorphous region itself, and the hydrogen bond by the amide bond acts on the copolymer molecular chain around the rigid segment,
This is probably because the molecular motion is restricted.

[0031]

The present invention will be described in more detail with reference to the following examples, but the present invention is not limited to these examples as long as the gist of the present invention is not exceeded. The method for producing the precursor copolymer, the method for producing the copolymer by solid-state polymerization, the method for measuring the molecular weight, and the method for measuring various physical properties and performance are shown below.・ Production of precursor copolymer 2 mol of terephthalic acid, 3 mol of ethylene glycol, antimony trioxide as a catalyst (2 × with respect to terephthalic acid)
10 ^-4 mol), and a predetermined molar amount of the amino group-containing compound with respect to terephthalic acid is charged in a reaction vessel equipped with a stirrer
After sufficiently replacing with nitrogen gas, the inside of the reaction vessel was pressurized with nitrogen gas to 1.8 kg / cm ² , and the reaction was carried out at 240 ° C. After removing the theoretical amount of water and by-products out of the system, 4
0 mmHg, 255 ° C. for 60 minutes, 15 mmHg, 27
A polycondensation reaction was carried out at 0 ° C. for 60 minutes at 1 mmHg and 275 ° C. until a predetermined molecular weight was reached, and immediately after the reaction was completed, it was cooled in ice water to obtain a precursor copolymer. -Production of copolymer by solid phase polymerization After completion of the polycondensation reaction, the precursor copolymer rapidly cooled in ice water was used.
Cut into pellets of mm to 3 mm, put in a rotary vacuum heating and drying device connected to a vacuum exhaust system,
Crystallization and preliminary drying were performed for 2 hours at a stirring speed of rpm. Then, the temperature of (melting point -18 ° C) of each sample, 5 rp
Solid-state polymerization was performed for a predetermined time at a stirring speed of m to obtain a copolymer.・ Measurement of molecular weight 5.0 mg of copolymer was added to 0.1 ml of 1,1,1,3,3.
After dissolving in 3,3-hexafluoro-2-propanol, 12.5 ml of chloroform was added and sufficiently stirred, followed by measurement with a high-speed GPC (Tohso HLC8020). Weight average molecular weight at this time (converted to polystyrene)
Was calculated. -Measurement of initial elastic modulus At a room temperature of 24 ° C and a humidity of 55%, a filament having a sample length of 15 mm was used for 10 mm /
The initial elastic modulus was calculated from the slope of the tangent line of the rising edge of the load-elongation curve obtained at a pulling speed of a minute and the measured cross-sectional area of the filament. -Measurement of dry heat shrinkage rate at 177 ° C A load of 1/30 is applied to the fineness of the fiber sample to measure the sample length L _O , and the sample is left in an oven for 30 minutes at 177 ° C without any load to dry heat. Contracted. After that, remove the sample from the oven and let it cool in a desiccator for 30 minutes.
The sample length L ₁ is measured by applying a load of 1/30, and the sample length L _O
Variation from the (L _O -L ₁₎ is measured. The heat shrinkage rate was calculated by the following formula (1).

[0032]

[Equation 1]

Measurement of creep displacement amount under a load of 1 g / d at 100 ° C. With respect to the fineness of each fiber sample, after mounting the sample with an initial load of 0.2 g / d, the temperature was raised to 100 ° C. Start. 1 g / minute of the fineness of the fiber sample within 1 minute after the start of heating
The load is controlled to be d, and the displacement amount L _o at this time is measured. Then, the displacement amount L ₁ after 24 hours is measured at 100 ° C. The creep displacement is calculated by the following equation (2)
It was calculated by

[0034]

[Equation 2]

Measurement of thermal dimensional stability performance A sample was attached at an initial load of 0.02 g / d with respect to the fineness of a fiber sample at 20 ° C., and the sample length at this time was 1 _O.
And Thereafter, the temperature was raised to 170 ° C. for 5 minutes, to measure 1 ₁ is a heat shrinkage displacement amount at this time. Next, 170 ℃
The load is 0.5 g /
under a load of d, measuring the displacement of 1 ₂ from the initial sample length 1 _O after 25 minutes.

From the above 1 _O , 1 ₁ and 1 ₂ , 0.02 g
/ D Thermal contraction rate (%) at temperature rise of 170 ° C under load a and 0.5
The elongation displacement rate (%) b from the initial sample length after 25 minutes at 170 ° C. under a load of g / d is calculated by the following formula.

A = 1 ₁ 1 _O × 100 (%) b = 1 ₂ / _1O × 100 (%) Next, the thermal shrinkage rate a and the elongation displacement rate b of each fiber are added to obtain thermal dimensional stability. The performance index is shown in Table 1 with a thermal dimensional stability performance index of less than 10 as ◯, 10 or more and less than 11 as Δ, and 11 or more as x.

The smaller the value of the thermal dimensional stability figure of merit, the better the thermal dimensional stability. That is, in the case of molding processing involving heating and expansion, good thermal dimensional stability is achieved only when the heat shrinkage characteristics, high temperature creep characteristics, and elastic characteristics are well matched. Example 1 According to the method for producing a precursor copolymer described above,
Ethyl p-aminobenzoate as an amino group-containing compound was added in an amount of 1.0 mol% with respect to terephthalic acid to carry out a copolymerization reaction to obtain a precursor copolymer having a weight average molecular weight of 8.3 × 10 ⁴ . According to the method for producing a copolymer by solid phase polymerization, the precursor copolymer was pelletized and then solid phase polymerized at 230 ° C. under reduced pressure for 12 hours to obtain a copolymer. The content of ethyl p-aminobenzoate units in this copolymer was 1.0 mol% based on the terephthalic acid units. The weight average molecular weight was 13.1 × 10 ⁴ .

After that, after being melted at 305 ° C., spun through a nozzle, passed through an atmosphere controlled at 250 ° C. by a heating zone immediately below the nozzle, then cooled and solidified at 20 ° C. under cooling air of 1.0 m / sec, and then 500 m. The undrawn yarn was wound at a speed of 1 / min. This unstretched yarn is stretched 4 times at a stretching temperature of 70 ° C. and then stretched at a second stretching temperature of 170 ° C. with a total stretching ratio of 5.8 times, and then heat treated at 170 ° C. without relaxing. Then, a drawn yarn was obtained. The physical properties and performance of this drawn yarn are shown in Table 1. [Comparative Example 1] Ethyl p-aminobenzoate as an amino group-containing compound was added in an amount of 1.0 mol% with respect to terephthalic acid to carry out a copolymerization reaction to obtain a copolymer having a weight average molecular weight of 8.5 x 10 ^4. Obtained. The content of ethyl p-aminobenzoate units in this copolymer was 1.0 based on terephthalic acid units.
It was mol%.

The physical properties and performance of the drawn yarn obtained in the same manner as in Example 1 are shown in Table 1 after pelletizing the copolymer and vacuum drying. [Example 2] Ethyl p-aminobenzoate as an amino group-containing compound was added in an amount of 5.0 mol% with respect to terephthalic acid, and a copolymer reaction was carried out to obtain a weight average molecular weight of 9.1 x 10 9.
A precursor copolymer of ⁴ was obtained. After pelletizing the precursor copolymer, solid phase polymerization was performed at 220 ° C. under reduced pressure for 10 hours to obtain a copolymer. The content of ethyl p-aminobenzoate units in this copolymer is based on terephthalic acid units,
It was 5.0 mol%. The weight average molecular weight is 1
It was 3.7 × 10 ⁴ .

Then, Table 1 shows the physical properties and performances of the drawn yarn obtained in the same manner as in Example 1. [Comparative Example 2] Ethyl p-aminobenzoate as an amino group-containing compound was added in an amount of 5.0 mol% with respect to terephthalic acid to carry out a copolymerization reaction to obtain a copolymer having a weight average molecular weight of 9.2 x 10 ^4. Obtained. The content of ethyl p-aminobenzoate unit in this copolymer was 5.0 based on terephthalic acid unit.
It was mol%. The physical properties and performance of the drawn yarn obtained in the same manner as in Example 1 are shown in Table 1 after pelletizing the copolymer and vacuum drying. [Comparative Example 3] Using a precursor polymer pellet of polyethylene terephthalate having a weight average molecular weight of 5 x 10 ⁴ produced by the same method as the precursor copolymer of Example, solid phase polymerization was carried out for 12 hours under reduced pressure at 237 ° C. Weight average molecular weight 8.2
A polyethylene terephthalate (PET) of × 10 ⁴ was obtained. Then, Table 1 shows the physical properties and performance of the stretched system obtained in the same manner as in Example 1. Comparative Example 4 Polyethylene naphthalate precursor polymer pellets having a weight average molecular weight of 4.5 × 10 ⁴ prepared in the same manner as the precursor copolymer of the example were used, and solid phase polymerization was performed under reduced pressure at 255 ° C. for 10 hours. And a weight average molecular weight of 6.
3 × 10 ⁴ polyethylene naphthalate (PEN) was obtained. Then, Table 1 shows the physical properties and performance of the stretched system obtained in the same manner as in Example 1.

[0042]

[Table 1]

As shown in Table 1, the polyester-based copolymer fiber of the present invention has a copolymer having a predetermined molecular structure, preferably a high molecular weight, and the fiber obtained has an initial elastic modulus of 12. × 10 ⁵ g / mm ² or more, heat shrinkage rate is 8.0% or less, and creep displacement is 0.5.
It can be seen that the thermal dimensional stability performance is excellent in each physical property value range such as%.

As shown in Comparative Examples 1 and 2, a fiber using a copolymer having the same molecular constitution as the terpolymer used in the present invention but having a low molecular weight level has a high elastic modulus, Although it exhibits a low heat shrinkage, its thermal dimensional stability is not good because its creep property at high temperatures is outside the scope of the claims of the present invention. As shown in Comparative Example 3, since the two-component commercially available polyethylene terephthalate fiber has all three physical properties outside the scope of the claims as compared with the fiber of the present invention, the effect of the present invention cannot be obtained. Also, the effect is small compared to the fibers of Comparative Examples 1 and 2. The polyethylene naphthalate fiber shown in Comparative Example 4 has an elastic modulus and a heat shrinkage ratio within the ranges, but the creep property at a high temperature is outside the range, and thus the level of thermal dimensional stability is low. From the above, it is understood that the fiber of the present invention satisfies the three physical properties at the same time, and thus the thermal dimensional stability performance is significantly improved.

[0045]

Since the polyester-based copolymer fiber of the present invention has the above-mentioned constitution, it has an excellent effect of showing a high level of thermal dimensional stability.

Claims (8)

[Claims] 1. A terephthalic acid, an ethylene glycol, at least one of the amino group-containing compounds represented by the following general formula (I) or (II), and a copolymer obtained from the copolymer, and having an initial elastic modulus of 12 × 10. ⁵ g / mm ² or more, dry heat shrinkage at 177 ° C is 8.0% or less, and creep displacement at 100 ° C under a load of 1 g / d is 0.5% or less. And polyester-based copolymer fiber. General formula _{(I) H 2 N-A} 1 -COOR 1 formula _{(II) H 2 N-A} 2 -CONH-CH 2 -CO
OR ² (In the formula, A ¹ and A ² represent an aromatic hydrocarbon group having 6 to 12 carbon atoms and may be the same or different.
¹ and R ² represent a hydrogen atom or an alkyl group having 1 to 3 carbon atoms, and may be the same or different. ) 2. The weight average molecular weight of the copolymer is 10 ×.
The polyester-based copolymer fiber according to claim 1, wherein the number is 10 ⁴ or more. 3. The amino group-containing compound is p-aminobenzoic acid, m-aminobenzoic acid, methyl p-aminobenzoate, methyl m-aminobenzoate, ethyl p-aminobenzoate, m-aminobenzoic acid. Ethyl, p-aminohippuric acid, m-aminohippuric acid, methyl p-aminohippurate, m-
At least one selected from the group consisting of aminomethyl hippurate, ethyl p-aminohippurate, and ethyl m-aminohippurate.
The polyester-based copolymer fiber according to claim 1, which is one compound. 4. The content of the amino group-containing compound unit in the copolymer is relative to the terephthalic acid unit in the copolymer,
It is 0.5-30 mol%, The polyester-type copolymer fiber of Claim 1 characterized by the above-mentioned. 5. The content of the amino group-containing compound unit in the copolymer is relative to the terephthalic acid unit in the copolymer,
The polyester-based copolymer fiber according to claim 1, which is 0.5 to 20 mol%. 6. The initial elastic modulus is 12 × 10 ⁵ g / mm
The polyester-based copolymer fiber according to claim 1, wherein the number is ² or more. 7. The dry heat shrinkage ratio at 177 ° C. is 8.
It is 0% or less, The polyester type copolymer fiber of Claim 1 characterized by the above-mentioned. 8. The polyester-based copolymer fiber according to claim 1, wherein a creep displacement amount under a load of 1 g / d at 100 ° C. is 0.5% or less.