JPH07189036A - Polyester conjugate fiber - Google Patents

Abstract

PURPOSE:To provide a polyester conjugate fiber lowered in the quantity of light reflected from the surface of the fiber not only to improve the color depth of the fiber but also to improve the dyeability of the fiber without deteriorating the excellent original performance of the polyethylene terephthalate fiber. CONSTITUTION:The characteristic of the conjugate fiber comprising a polyester A containing ethylene terephthalate units as main repeating units as a core component and a polyester B containing ethylene terephthalate units as main repeating units and copolymerized with 5-30mol.% of cyclohexanedicarboxylic acid as a sheath component comprises that the glass transition temperature of the component B is lower than the glass transition temperature of the polyester A.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a polyester-based composite fiber which is excellent in dyeability and bathochromatism.

[0002]

2. Description of the Related Art Polyester fibers are widely used because they have many excellent properties, but they are sharper and have a deeper color depth than natural fibers such as wool and silk, and semi-synthetic fibers such as rayon and acetate. In particular, there is a problem that the density of black color and the color developability are poor. This defect is caused by the fact that polyester fiber is dyed with a disperse dye with poor sharpness, and that the refractive index of the polyester fiber in the fiber axis direction is about 1.7, which is higher than other fibers and the light on the fiber surface And the like, and as a result, the intensity of white reflected light from the surface of the cloth increases. As a solution to these problems, polyester fibers have been modified by introducing seats that can be dyed with clear dyes such as cationic dyes and acid dyes. The fact is that the surface-reflected light based on the rate does not decrease, and the color depth is not essentially improved.

On the other hand, a method of suppressing reflection on the fiber surface by forming fine irregularities on the surface of the fiber has also been proposed (for example, Japanese Patent Publication No. 59-24233 and Japanese Patent Publication No. 62-20).
304, Japanese Patent Publication No. 62-28229). It is also known that when the fiber surface is covered with a compound having a low refractive index, the color appears dark and the depth increases. Up to now, a method of coating a low refractive index compound such as an organic fluorine compound or an organic silicon compound on the fiber surface has been proposed (for example, Japanese Patent Publication No.
-42938).

[0004]

However, the fibers having fine irregularities formed on the surface of the fibers are damaged in the processing step and the performance is deteriorated, or the fibers are worn while actually worn. Therefore, the appearance may be deteriorated. Further, a fiber whose surface is covered with a compound having a low refractive index has poor durability against dry cleaning, rubbing, etc., and in order to obtain a sufficient dark color effect, a larger amount of the compound than that used in usual processing is used. However, even if a dark color effect is achieved, problems such as a change in texture and a decrease in the fastness of the dyed product occur. Furthermore, in the case of the combination of polyester and other types of low refractive index resins, there is a problem in the adhesiveness at the interface between the two and it is also impossible to carry out a texture improving treatment such as alkali weight reduction which is possible in polyester fibers.
An object of the present invention is to provide a polyester-based composite fiber which is excellent in dyeability and bathochromic property without impairing the physical properties of polyethylene terephthalate fiber.

[0005]

Means for Solving the Problems As a result of intensive studies made by the present inventors to solve the above-mentioned drawbacks, a core-sheath type polyester conjugate fiber using polyethylene terephthalate having a specific composition as a sheath component is The inventors have found that the objects can be achieved and have reached the present invention.

That is, in the present invention, the polyester A having ethylene terephthalate units as the main repeating units is used as the core component, the ethylene terephthalate units as the main repeating units, and the cyclohexanedicarboxylic acid is used as 5 to 5.
A polyester-based composite fiber comprising 30 mol% of copolymerized polyester B as a sheath component, wherein the glass transition temperature of the copolymerized polyester B is lower than the glass transition temperature of the polyester A.

The sheath component constituting the polyester-based conjugate fiber of the present invention will be described. In the present invention, the polyester B as the sheath component needs to copolymerize cyclohexanedicarboxylic acid. By such copolymerization, a part of the aromatic ring of terephthalic acid that constitutes the polyester B can be replaced with the alicyclic skeleton of cyclohexanedicarboxylic acid, and as a result, the concentration of the aromatic ring can be reduced and the refractive index can be increased. Can be kept low. Further, even when the fibers are oriented and oriented, the concentration of the oriented aromatic rings is reduced, so that the increase in the refractive index in the fiber axis direction due to the orientation can be suppressed. Aliphatic dicarboxylic acids are also considered in the sense of lowering the concentration of aromatic rings of terephthalic acid, but when a large amount of the aliphatic dicarboxylic acids are copolymerized, the glass transition temperature of the polyester is extremely lowered, and the heat resistance as a fiber, dyeing Robustness is extremely reduced.

In the polyester B which is the sheath component, the amount of cyclohexanedicarboxylic acid copolymerized in the polyester B is in the range of 5 to 30 mol%. When the copolymerization amount of cyclohexanedicarboxylic acid is more than 30 mol%, the crystallinity and melting point of polyester B are lowered, and the heat resistance usually required for polyester fibers cannot be obtained. On the other hand, when the copolymerization amount of cyclohexanedicarboxylic acid is less than 5 mol%, the effect of introducing an alicyclic skeleton into the polyester and the effect of lowering the refractive index by lowering the crystallinity are insufficient, and sufficient bathochromism is obtained. I can't. The copolymerization amount of cyclohexanedicarboxylic acid is preferably in the range of 10 to 25 mol% in order to impart sufficient bathochromic properties to the fiber.

Cyclohexanedicarboxylic acid copolymerized with polyester B includes 1,2-cyclohexanedicarboxylic acid and 1,3-cyclohexanedicarboxylic acid.
Although there are three types of regioisomers of 1,4-cyclohexanedicarboxylic acid, any regioisomer may be used or a mixture thereof may be used from the viewpoint of obtaining the effects of the present invention. Although each position isomer has a cis / trans stereoisomer, any stereoisomer may be used, or a mixture thereof may be used.

By copolymerizing cyclohexanedicarboxylic acid, the glass transition temperature of polyester B as the sheath component can be made lower than that of polyester A as the core component, and as a result, the core component can be stretched during stretching. While orienting the polyester A, the orientation of the sheath component polyester B can be suppressed. Therefore, the mechanical and thermal properties such as strength, elongation and heat shrinkage of the yarn as a whole can be retained by the highly oriented core component, while the refractive index that affects the appearance of the fiber is the sheath. It can be lowered by making the component have a specific copolymer composition and low orientation.

The glass transition temperature of polyester B as the sheath component may be lower than the glass transition temperature of polyester A as the core component, but it is particularly preferably 5 to 30 ° C. lower.
If the temperature difference is less than 5 ° C or less, a large difference in orientation between the core component and the sheath component may not be observed, and if the temperature difference exceeds 30 ° C, the glass transition temperature of the sheath component becomes too low, resulting in heat resistance and dyeing. Problems such as firmness of wax may occur.

Except for some special ones having a cumulative alicyclic skeleton, the glass transition temperature of polyester generally decreases as the content of alicyclic dicarboxylic acid increases. Cyclohexanedicarboxylic acid may be copolymerized so that the difference in glass transition temperature from A is within the above range. The melting point and crystallinity decrease as the amount of cyclohexanedicarboxylic acid copolymerized increases,
Since the bathochromic property is improved, the required mechanical properties, heat resistance,
The amount of copolymerization may be changed within the range of the present invention in consideration of bathochromic property.

In the present invention, the intrinsic viscosity of both the polyester A as the core component and the polyester B as the sheath component [measured at 30 ° C. using a mixed solvent of phenol / tetrachloroethane (weight ratio 50/50)] is 0.4 to 1 It is preferably 0.5.

As the core component polyester A, ethylene glycol is used as a raw material glycol, and terephthalic acid or a lower alkyl or phenyl ester thereof is used as a raw material dicarboxylic acid. In addition, the polyester component B of the sheath component is ethylene glycol as a raw material glycol,
It can be obtained by polymerization using cyclohexanedicarboxylic acid and terephthalic acid or their lower alkyl or phenyl ester as the starting carboxylic acid.
Esterification or transesterification reaction is carried out using such a raw material to prepare a low polymer thereof, and then a polycondensation catalyst such as antimony trioxide, germanium oxide or tetraalkoxytitanium is used under reduced pressure at 230 to 300 ° C. A condensation reaction is performed to adjust the viscosity to a desired value. In addition, after the polymerization is performed in the liquid phase as described above, the polymerization degree may be further increased by the solid phase polymerization to increase the intrinsic viscosity.

In the present invention, polyester A and polyester B are isophthalic acid, phthalic acid, naphthalene dicarboxylic acid, diphenyl dicarboxylic acid, diphenyl ether dicarboxylic acid, diphenyl sulfone dicarboxylic acid, diphenyl ketone dicarboxylic acid within a range not impairing the effects of the present invention. Acids, aromatic dicarboxylic acids such as sodium-sulfoisophthalic acid; hydroxycarboxylic acids such as glycolic acid, hydroxyacrylic acid, hydroxypropionic acid, asiatic acid, quinobaic acid, hydroxybenzoic acid, mandelic acid, and matrolactic acid; ε-caprolactone And other aliphatic lactones; trimethylene glycol, tetramethylene glycol, hexamethylene glycol, neopentyl glycol, diethylene glycol, polyethylene glycol, and other fats Diols; hydroquinone, catechol, naphthalene diol, resorcin, bisphenol A, ethylene oxide adduct of bisphenol A,
Aromatic diols such as bisphenol S and ethylene oxide adducts of bisphenol S; alicyclic diols such as cyclohexanedimethanol may be copolymerized. Further, polyvalent carboxylic acids such as trimellitic acid, trimesic acid, pyromellitic acid, and tricarballylic acid within a range where the polyester A and the polyester B are substantially linear; glycerin, trimethylolethane, trimethylolpropane, penta It is also possible to copolymerize a polyhydric alcohol such as erythritol.

No special method is required to use the thus obtained polyester as a fiber, and a usual melt-composite spinning method for polyester fiber is arbitrarily adopted. The composite ratio of the core and the sheath of the composite fiber is not particularly limited, but the core / sheath = 3/7 to 9/1 (weight ratio) is preferable. Further, the cross-sectional shape of the spun fiber may be circular or irregular, and the cross-sectional shape of the core component may be circular or irregular. The cross-sectional shapes of the core component and the sheath component may be the same or different.

The polyester composite undrawn yarn thus obtained is subsequently drawn. At this time, the stretching may be roll stretching with a hot roller or stretching in a hot water bath. The stretching temperature and the stretching speed are not particularly limited, but it is preferable that the stretching is performed under the condition that the polyester A as the core component is sufficiently oriented and the orientation of the polyester B as the sheath component is suppressed. In the case of ordinary roll drawing, it is preferable that the heating roll temperature is a temperature slightly higher than the glass transition temperature of the polyester A as the core component. Thereafter, if necessary, heat treatment, false twisting, or the like may be performed, or a fabric may be further dyed. In addition, alkali reduction treatment can be performed when the cloth is formed.

The polyester-based conjugate fiber of the present invention may be added to the polyester-based composite fiber of the present invention, if necessary, within a range not impairing the effects of the present invention.
Other thermoplastic resins are used in a small amount in a supplementary manner, or substances that are generally added to thermoplastic resins, that is, stabilizers such as UV absorbers, optical brighteners, matting agents, antistatic agents, difficult It is also possible to add a flame retardant, a flame retardant auxiliary agent, a lubricant, a plasticizer, an inorganic filler and the like.

[0019]

In the polyester-based conjugate fiber of the present invention, the aromatic ring of terephthalic acid constituting the polyester B can be replaced with an alicyclic skeleton by modifying the sheath component polyester B with cyclohexanedicarboxylic acid. As a result, the concentration of aromatic rings can be reduced and the refractive index can be suppressed low. Further, since the concentration of the aromatic ring to be oriented is lowered even when oriented, it is possible to suppress the increase in the refractive index in the fiber axis direction due to the orientation. Further, by lowering the glass transition temperature of the polyester B as the sheath component to that of the polyester A as the core component, the orientation of the polyester B as the sheath component can be suppressed while orienting the polyester A as the core component during stretching. It is possible. Therefore, the mechanical and thermal properties such as strength, elongation and dry heat shrinkage of the whole yarn can be retained by the highly oriented core component, while the refractive index that affects the appearance of the fiber. With respect to the above, it is possible to reduce the content by making the sheath component a specific copolymer composition to have a low orientation. In this way, in the present invention, since the reflectance of the fiber surface can be reduced, surface reflected light can be suppressed,
A fiber having excellent bathochromism can be provided. Therefore,
It is a fiber having excellent bathochromism that overcomes the drawbacks of conventional polyester fibers, and is useful as various fiber products.

[0020]

The present invention will be described in more detail below with reference to examples, but the present invention is not limited to these examples. In addition, the measuring method of each physical property used in the Example is shown below. (1) Copolymerization rate (mol%) of the monomer introduced into the polyester molecule It was calculated based on the ¹ H-NMR measurement result of the copolymerized polyester using deuterated trifluoroacetic acid as a solvent. (2) Intrinsic viscosity of polyester Phenol / tetrachloroethane (weight ratio 50/50)
The mixed solvent of was used and the solution viscosity measured at 30 ° C. was used.

(3) Glass transition temperature of polyester (T
g) Measured at a temperature rising rate of 10 ° C./min by a differential thermal analysis method (DSC) based on JIS K7121. (4) Polyester melting point (Tm) and crystallinity (△
H) The sample chip was heat-treated at 140 ° C. for 18 hours under a nitrogen stream to be crystallized, and then the crystal melting peak (° C.) and its heat quantity (J /
g) was determined and used as the melting point and crystallinity.

(5) Fiber Strength (g / d), Elongation (%) Measured in accordance with JIS L 1013. (6) Hot water shrinkage (WSr,%) The sample was marked at 50 cm intervals under an initial load of 1 mg / denier, and then the sample was placed in hot water at 98 ° C. for 5 minutes under a load of 5 mg / denier. After leaving it for a while, it was taken out and the distance L ₁ cm between the marks was measured under a load of 1 mg / denier and calculated by the following formula. Wsr (%) = [(50-L ₁ ) / 50] × 100 (7) Dry heat shrinkage (DSr,%) Initial load of 1 mg / denier was applied to the sample at 50 cm intervals, and then the sample was marked. The sample was left in a dry heat atmosphere heated to 180 ° C. for 10 minutes under a load of 5 mg / denier, then taken out, and under a load of 1 mg / denier, a mark interval L ₂ cm.
Was measured and calculated by the following formula. Dsr (%) = [(50−L ₂ ) / 50] × 100

(8) Refractive index of fiber When the drawn yarn is dipped in a solvent having a known refractive index and observed under a microscope under polarized illumination in the same direction as the fiber axis, the focus is shifted up and down before and after focusing. The refractive index of the solvent when the Becke line was not observed was defined as the refractive index in the axial direction of the sheath component polymer of the fiber. (9) Dyeing ratio (%) The dyeing solution was diluted to a predetermined concentration with a mixed solution of acetone / water in a volume ratio of 1/1, and the absorbance of the diluted solution was measured with a spectrophotometer. The dyeing rate was calculated according to the following formula using the absorbance at the maximum absorption. Dyeing rate (%) = [(B−A) / B] × 100, where B is the absorbance of the diluted dyeing solution before dyeing, A is the absorbance of the diluted dyeing solution after dyeing (10) Chromaticity (K / S) Using the dyed sample, it was calculated from the following equation of Kubelka-Munk. K / S = (1-R) ² / 2R where R is the reflectance at the maximum absorption wavelength

Example 1 From a dicarboxylic acid raw material consisting of 16 mol% of 1,4-cyclohexanedicarboxylic acid (cis / trans = 55/45) and 84 mol% of terephthalic acid and ethylene glycol, a molar ratio of diol raw material: terephthalic acid. Is 1.2: 1
To form a slurry, and pressurize the slurry (absolute pressure 2.5 kg / cm ² ) at a temperature of 250 ° C.
Then, an esterification reaction was carried out until the esterification rate reached 95% to produce a low polymer. Next, 350ppm as a catalyst
Antimony trioxide was added and melt polycondensation was performed at 280 ° C. for 1.5 hours under a reduced pressure of 1 torr absolute pressure to produce polyester B having an intrinsic viscosity of 0.72 dl / g. This polyester B was extruded in a strand form from a nozzle and cut to produce a cylindrical chip having a diameter of 2.8 mm and a length of 3.2 mm. When the obtained chip was analyzed by ¹ H-NMR, this polyester B was found to have 1,4-cyclohexanedicarboxylic acid units in 16% of all dicarboxylic acid units.
It was confirmed to be a copolyester containing mol%. Further, the DSC of the obtained chip was 62 ° C., the melting point was 216 ° C., and the heat of crystallization was 2
It was 5 J / g.

In the same manner as above, chips of polyethylene terephthalate (polyester A) for the core component were produced by using terephthalic acid as the only dicarboxylic acid component.
The intrinsic viscosity was 0.68 dl / g. The two types of polyester chips produced above were dried by a conventional method, and polyethylene terephthalate was used as a core component, and polyester B was used as a sheath component, and 36 concentric circular holes having a diameter of 0.25 mm were formed. Using a composite spinneret, polymer chips were fed so that the ratio of the core component to the sheath component was 1: 1 (weight ratio), and the spinning speed was 1000 m / min.
An undrawn yarn was obtained by spinning at 0 ° C. This is drawn at a stretching speed of 35
Stretching heat treatment is performed using a heating roller of 0 m / min, 85 ° C. and a plate heater of 150 ° C., and 75 denier / 3
A drawn filament of 6 filaments was obtained. The physical properties of the obtained drawn yarn are as follows: strength 3.9 g / dr, elongation 48%, hot water shrinkage 10
%, Dry heat shrinkage 16%, refractive index in the fiber axis direction is 1.61
Met.

Using this filament as a warp and a weft, taffeta was woven. The machine density is 79 warps /
Inch, weft 72 threads / inch. 2 g / l of sodium carbonate and Actinol R-1
00 (made by Matsumoto Yushi Co., Ltd.) in a 1 g / l mixing bath at 100 ° C.
After desizing for 0 minutes, presetting at 180 ° C with a tenter, dyeing at 130 ° C for 40 minutes with the following chemical composition, and then hydrosulfite 1 g /
Reduction washing was performed in a mixed bath of 1, 1 g / l of sodium hydroxide, and 1 g / l of amylazine (Daiichi Kogyo Seiyaku Co., Ltd.). (Dyeing liquid composition) -Dye; Sumikaron Red S-BL (Sumitomo Chemical) 3% owf-Dispersant: Disper TL (Meisei Chemical)) 1 g / l-PH adjuster; Acetic acid 0.5 cc / l-Bath ratio 50/1 The bathochromaticity of the obtained dyed product was K / S = 21.3.

Examples 2 to 7 As the polyester B as the sheath component, a core-sheath type composite fiber was spun in the same manner as in Example 1 except that the copolymerization amount of 1,4-cyclohexanedicarboxylic acid was as shown in Table 1. And stretched. Table 2 shows the physical properties of these conjugate fibers. Table 2 shows the results of weaving, dyeing and evaluating these composite fibers in the same manner as in Example 1.

Comparative Examples 1 to 3 As the sheath component polyester B, the copolymerization amount of 1,4-cyclohexanedicarboxylic acid was 4 mol% (Comparative Example 1), 3
2 mol% (Comparative Example 2) and 16 mol% of 1,4-cyclohexanedimethanol copolymerized (Comparative Example 3) were used in the same manner as in Example 1 to prepare a core-sheath composite fiber. Was spun and stretched. Table 2 shows the physical properties of these conjugate fibers. In addition, the results of weaving, dyeing, and evaluating these composite fibers in the same manner as in Example 1 are shown in Table 2.
Shown in. In the fiber obtained in Comparative Example 2, the amount of cyclohexanedicarboxylic acid copolymerized was too large and a part of the fiber was stuck during stretching.

Reference Examples 1 and 2 Polyethylene terephthalate obtained by copolymerizing 16 mol% of 1,4-cyclohexanedicarboxylic acid (Reference Example 1) and polyethylene terephthalate having an intrinsic viscosity of 0.68 dl / g (Reference Example 2) were used alone. Was spun and stretched. Table 2 shows the physical properties of these conjugate fibers.
Table 2 shows the results of weaving, dyeing and evaluating these composite fibers in the same manner as in Example 1.

[0030]

[Table 1]

[0031]

[Table 2]

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Kiyoshi Hirakawa 1621 Sakata, Kurashiki City, Okayama Prefecture Kuraray Co., Ltd.

Claims (2)

[Claims] 1. A polyester obtained by using a polyester A having an ethylene terephthalate unit as a main repeating unit as a core component, an ethylene terephthalate unit as a main repeating unit, and copolymerizing cyclohexanedicarboxylic acid in an amount of 5 to 30 mol%. A polyester composite fiber comprising B as a sheath component, wherein the glass transition temperature of polyester B is lower than the glass transition temperature of polyester A. 2. The polyester-based composite fiber according to claim 1, wherein the glass transition temperature of polyester B is 5 to 30 ° C. lower than the glass transition temperature of polyester A.