JPH04100917A - rectangular cross section polyester fiber - Google Patents

Abstract

PURPOSE:To obtain the subject fiber, composed of a special modified polyester, having a specific cross-sectional shape and see-through preventive properties, capable of providing high-class soft woven or knitted fabrics having milky luster and dry hand and excellent in dyeability, yarn strength, etc. CONSTITUTION:The objective fiber is composed of modified polyester fiber, obtained by respectively copolymerizing a metal sulfonate group-containing isophthalic acid component in an amount of 0.7-2.4mol% based on the total dicarboxylic acid component and a polyalkylene glycol component having 90-6000 molecular weight in an amount of 0.2-10wt.% based on the polyester and containing 1.3-8wt.% delustering agent. The aforementioned fiber has a rectangular fiber cross-sectional shape at 1.2-2.2 ratio (A/B) of the length (A) of long sides to the length (B) of short sides in the rectangular cross section and respectively 1-4 recessed parts on the surfaces of the long sides and 1-3 recessed parts on the surfaces of the short sides. Furthermore, the ratio (D/C) of the depth (D) to the inlet width (C) of the recessed parts is 0.2-1.

Description

[Detailed Description of the Invention] [Industrial Application Fields] The present invention provides an anti-transparent material with good dyeability, high yarn strength, excellent color development (deep color) and sharpness, and a milky color. This invention relates to rectangular cross-section polyester fibers suitable for high-grade woven and knitted fabrics, which have a new, glossy, soft, and unique smooth feel.

[Prior Art] Polyester fibers have excellent physical and chemical properties and are therefore widely used for clothing and industrial purposes. Particularly in the field of clothing, various fibers with irregular cross-sections have been developed with the aim of increasing the quality of the clothing, and among these, many technologies have been disclosed regarding fibers having irregularities on the outer peripheral surface of the fibers.

For example, Japanese Patent Application Laid-Open No. 56-112535 has six grooves with a width of 0.1 to 4μ and a depth of 2 to 1Oμ continuous in the fiber axis direction.
Fibers with excellent water absorption properties have been proposed (FIG. 4), but because of the deep grooves, the color development and sharpness are poor. Another disadvantage is that the original cross-sectional shape cannot be maintained during high-level processing of the fiber, wearing of clothing, washing, etc., and furthermore, it is easily fibrillated.

JP-A No. 62-97909 discloses that a total of four or more recesses exist symmetrically from the left and right surfaces toward the axis with a straight line passing approximately through the center of the cross section of the fiber as an axis of symmetry, and the depth of the recess is A special cross-section yarn has been proposed (Fig. 5) that has fibers larger than its width and has a soft and smooth silk-like texture, luster, and deep coloring effect, as disclosed in the above-mentioned Japanese Patent Application Laid-Open No. 58-1125.
It has the same drawbacks as Publication No. 35. Japanese Patent Publication No. 82-2233
No. 21 and Japanese Unexamined Patent Publication No. 63-105114 disclose that the surface of the fibers is given unevenness by treatment with an alkaline aqueous solution, resulting in a smooth texture, moderate flash effect, improved color development, and deep color tones. It has been proposed that fibers with a flat cross section (Fig. 6) or an elliptical cross section (Fig. 7) can be obtained, but these fibers have sharp unevenness, and when made into woven or knitted fabrics, they have a crisp taste. It is strong and lacks a soft feel.

JP-A-50-59524 proposes a polyester fiber with an oval cross section having four lobes suitable for fur-like pile fabrics (Fig. 8), but with no recesses in the long sleeve direction (Fig. Lacks color development, clarity and elegant luster.

JP-A-57-51808, JP-A-58-81.8
In Publication No. 1 and Japanese Unexamined Patent Publication No. 190083/1983,
Flat yarns with constrictions have been proposed to obtain animal hair-like artificial fibers and artificial fur (Figures 9 and 10), but none of them have concave portions in the long sleeve direction and are easily bent in the short axis direction. Therefore, when woven or knitted fabrics are used, they lack firmness and elasticity and tend to become sticky.

On the other hand, basic dye-dyeable polyester is well known as a polymer with excellent dyeability. Conventionally, as basic dye dyeable polyesters, those obtained by copolymerizing an isophthalic acid component having a metal sulfonate group, such as a 5-sodium sulfoisophthalic acid component, have been known as disclosed in Japanese Patent Publication No. 34-10497.

However, in order to raise the dyeability to a satisfactory level, this product must be copolymerized with a large amount of an isophthalic acid component (hereinafter abbreviated as S component) having a metal sulfonate group. When a large amount of the S component is copolymerized, the polymer whose degree of polymerization has been increased to a level required for fibers becomes difficult to spin due to the thickening effect of the S component. Therefore, in order to spin a polymer copolymerized with a large amount of the S component by a conventional method, it is necessary to lower the degree of polymerization of the polymer to a range where the melt viscosity can be normally used for spinning. However, as a result, the yarn strength decreases,
There were drawbacks such as deterioration in thread-spinning properties and passability through higher-order processes, and drawbacks in which its uses were limited. Furthermore, the addition of a large amount of S component also causes a decrease in the alkali resistance of the yarn and a decrease in the light fastness of the dyed product, which also limits the uses of the resulting polyester yarn.

On the other hand, especially in the field of thin clothing, it is important to control light transmittance,
For the purpose of preventing so-called see-through, polyester fibers containing a matting agent such as titanium oxide as a light shielding agent are widely used.

In addition, particles such as titanium oxide not only act as a light shielding agent, but also have the effect of eliminating the sliminess characteristic of synthetic fibers in the final woven or knitted product, and imparting a dry touch feel and milky color.

This is because the matting agent in the fibers diffusely reflects light, and
It is thought that this is because the matting agent on the fiber surface falls off due to the alkali weight loss treatment that is often performed when manufacturing woven or knitted fabrics, resulting in the appearance of fine irregularities on the fiber surface.

However, as consumer awareness regarding clothing has increased, consumer demands have become more diverse and sophisticated.
Conventional technology alone is no longer sufficient. Particularly in the case of high-quality woven and knitted fabrics, there is an increasing demand for so-called specialty products with color development and unique texture.

[Problems to be Solved by the Invention] The purpose of the present invention is to provide an anti-transparent material with good dyeability, high yarn strength, excellent color development (deep color) and clarity, milky luster, and softness. An object of the present invention is to provide a polyester fiber suitable for high-grade woven or knitted fabrics having a unique smooth and novel feel.

[Means for Solving the Problems J] The above-mentioned object of the present invention is to reduce the amount of isophthalic acid component containing a metal sulfonate group to 0.0% relative to all dicarboxylic acid components.
7 to 2.4 mol% polyalkylene glycol component with a molecular weight of 90 to 6,000 to the polyester
8. 10% by weight copolymerization and 1.3% by weight or more of a matting agent.
A fiber made of modified polyester containing 0% by weight or less, the cross-sectional shape of the fiber is rectangular as a whole, and when the length of the long side of the rectangular cross section is A and the length of the short side is B,
A/B is in the range of 1.2 to 2.2, and 1 on the long side surface.
~4 recesses, 1 to 3 recesses on the short side surface, and when the population width of the recess is 01 and the depth is D, D/C is 0.
This can be achieved with rectangular cross-section polyester fibers characterized by a polyester fiber having a polyester fiber with a polyester fiber having a polyester fiber having a polyester fiber having a rectangular cross-section.

Hereinafter, the polyester fiber of the present invention will be explained.

The greatest feature of the fiber of the present invention is its specific cross-sectional shape,
Although it has a rectangular shape as a whole, all its surfaces are uneven.

The cross-sectional shape will be explained below based on the drawings.

FIGS. 1A and 1B are cross-sectional views of typical fibers in the present invention. A virtual cross-sectional shape obtained by connecting the vertices of adjacent convex portions with a common tangent is a rectangular shape. The outer periphery of the cross-sectional shape of the fiber of the present invention has almost no straight parts and is composed of curved lines. In a rectangular shape in which the vertices of adjacent convex portions are connected by a common tangent, the length of the long side is indicated by A, and the length of the short side is indicated by B. In the present invention, the ratio A/B of the long side length A to the short side length B is an important factor for the color development level.1.
A range of 2 to 2.2 is required. A/BfJ<1.2
If it is less than A/B, no effect of improving color development is observed,
If it exceeds 2.2, the spinning properties and unwinding properties of the yarn will deteriorate, and when it is made into a woven or knitted fabric, it will have less firmness and stiffness and will tend to become sticky. Therefore, A/B is IJ~2.1
is preferable, and 1.4 to 2.0 is more preferable.

The fiber in the present invention has 1 to 4 recesses on the long side surface,
It is necessary to have 1 to 3 recesses on the short side surface. The concave portions are important for giving a smooth texture and soft feel to a woven or knitted fabric.

Here, a new smooth texture means that when you lightly touch the woven or knitted fabric, it feels "smooth", but when you touch it more strongly, you feel a moderate "squeak". This seems to be related to the area of the fibers that come into contact with the fingers when the fingers touch the woven or knitted fabric, and the shape and size of the fingerprint and the unevenness of the fibers. Therefore, one or more recesses are required on each of the short side surface and the long side surface, and 2 to 3 recesses are required on the long side surface.
It is preferable that there be one. If the number of recesses is too large, the new and smooth texture will be lost, so the number of recesses should be 4 or less on the long side surface and 3 or less on the short side surface. Further, by having an appropriate number of recesses, color development and clarity can be improved, and unique gloss can also be exhibited.

The size of the recess is defined as C, which is the length between the vertices of adjacent convex parts on each side (the entrance width of the recess), and the length of the perpendicular line drawn from the bottom point of the recess to the line connecting the vertices of the convex parts (the width of the recess). When D is the depth of 0.2≦D/C≦1.0. This is because if D is too large than C, color development, clarity, and gloss will be poor, and the fiber cross section will change during higher-order processes, wearing clothes, and washing.
This is also to prevent fibrillation from occurring easily. Therefore, D/C needs to be 1.0 or less. Also,
If D is too smaller than C, that is, if the depth of the recesses becomes shallow, not only will the smooth new texture be lacking, but also the color development, sharpness, and unique gloss will not be developed. Therefore, D/C needs to be 0.2 or more.

A preferable D/C is 0.3 to 0.8, and a more preferable D/C is 0.4 to 0.6.

4 to 10 are cross-sectional views showing examples of conventional fibers having unevenness, which are outside the scope of the present invention.

Next, the polyester in the present invention will be explained. The polyester in the present invention has an S component of 0.7 to 2.
A polyester copolymerized with 0.2 to 10% by weight of a polyalkylene glycol component having a molecular weight of 4 mol% and a molecular weight of 90 to 6000, and containing a matting agent of 1.3% to 8.0% by weight. .

By copolymerizing the glycol component in the S component copolymerization system, the following becomes possible.

One of them is that by copolymerizing the polyalkylene glycol component, satisfactory dyeing properties can be imparted even if the amount of copolymerization of the S component is reduced. This is because the polyalkylene glycol component has the function of increasing the effective utilization rate of the S component in the polymer for basic dyes. Secondly, by copolymerizing the polyalkylene glycol component, a polymer with a higher degree of polymerization can be obtained even if the melt viscosity is the same compared to the S component alone copolymerized system. This is because the polyalkylene glycol component has the function of lowering the melt viscosity of the polymer in the S component copolymerization system without lowering the degree of polymerization.

The polyester fiber of the present invention is a fiber having irregularities on the circumferential surface of the cross-section of the copolyester fiber, but only an S component copolymer that does not substantially contain polyalkylene glycol and has the same level of dyeability is used. It has the following effects compared to copolymerized polyester.

It has high yarn strength, good spinability and passability through higher processes,
High alkali resistance. In the dyeing and finishing process, an alkali weight reduction process is often applied, but since the polymer has high alkali resistance and the polymer itself has the ability to improve strength, the strength increases synergistically.

In the present invention, the S component is a compound represented by the following formula, specifically dimethyl (5-sodium sulfo) isophthalate, bis-2-hydroxyethyl (5-sodium sulfo) isophthalate, bis-4-hydroxy Examples include butyl (pentasodium sulfo) isophthalate.

AOOCCooΔ.

803M (However, M represents an alkali metal such as Na or Li5K, and A and A- represent -CH3 or -(CH2)nOH. n represents an integer of 2 or more.

) Preferred S components include dimethyl (5-sodium sulfo) isophthalate and bis-2-hydroxyethyl (5-sodium sulfo) isophthalate.
-sodium sulfo)isophthalate. S
The component must be copolymerized with the polyester in an amount of 0.7 to 2.4 mol%, preferably 0.9 to 2.0 mol%. If the S component is less than 0.7 mol %, satisfactory dyeing properties cannot be obtained even if the amount of glycol copolymerization is increased or the dyeing temperature is raised.

This is due to the lack of S component in the polymer that reacts with the basic dye. On the other hand, if the polymer contains more than 2.4 mol % of the S component, it will be difficult to spin it by a normal method due to the thickening effect. The polyalkylene glycol component must have a molecular weight in the range of 90 to 6,000. If the molecular weight is less than 90, the effect of improving dyeability will be small, which is not preferable. Furthermore, a polyalkylene glycol component having a molecular weight exceeding 6,000 is undesirable because it reduces the light fastness of dyed fibers obtained from a polymer copolymerized with the polyalkylene glycol component. A more preferable molecular weight of the polyalkylene glycol component is 1
00 to 4000, particularly preferably 100 to 1200
It is. Glycol components constituting polyalkylene glycol with a molecular weight of 90 to 6,000 include neopentyl glycol, 1,4-butanediol, 1,5-bentanediol, 1,6-hexanediol, 1,4 cyclohexane dimetatool, and bisphenol A. - ethylene oxide adducts, and more preferably polyalkylene glycols represented by the following formula.

A (C71H2n O), H (A is CnH2B +10 or OH,, is 1 to 10, U
(2 to 5, and 2 to 65 for corpse) The copolymerization amount of the polyalkylene gelcol component needs to be 0.2 to 10% by weight based on the polyester. If the amount is less than this range, the effect of improving dyeability will be small, and if it is more than this range, the physical properties, especially heat resistance, will be greatly reduced. Therefore 0.
A range of 3 to 7% by weight is more preferred.

The degree of polymerization of the polyester in the present invention is preferably 80 to 100, more preferably 90 to 100. If the degree of polymerization is too low, the yarn strength will not be at a satisfactory level, and if the degree of polymerization is too high, the melt viscosity of the polymer will increase, making spinning difficult, which is not preferred.

The fiber of the present invention contains the above-mentioned polyester and a matting agent of 1.
It is necessary that the content be 3% by weight or more and 8.0% by weight or less. When the content of the matting agent is less than 1.3% by weight, the anti-transparent properties, milky color, and dry touch feel are all unsatisfactory.

If the content of the matting agent exceeds 8.0% by weight, it is not good because the yarn strength decreases and fluffing or yarn breakage occurs during weaving or knitting. In addition, if the content of the matting agent exceeds 80% by weight, the P material will become clogged quickly during the spinning process, especially during polymer filtration during spinning, making stable spinning for a long time difficult, which is also undesirable. . From the above, the content of the matting agent is preferably 2.0 to 7.0% by weight.

The matting agents contained in the fibers of the present invention include titanium oxide, zirconium oxide, magnesium oxide, aluminum oxide, silicon oxide, antimony oxide, zinc oxide, lead tungstate, calcium tungstate, calcium carbonate, barium sulfate, etc. Any material may be used as long as it exhibits the effects of the invention and can be stably dispersed in polyester, but from the viewpoint of dispersibility, titanium oxide, silicon oxide, zinc oxide, and calcium carbonate are preferred, and titanium oxide is more preferred. The average particle diameter of the matting agent is preferably 1 micron or less, more preferably 0.7 micron or less, from the viewpoint of dispersibility.

Further, from the viewpoint of silk-spinning property, the maximum particle size is preferably 5 microns or less, more preferably 3 microns or less.

Although the dyeing temperature of the fibers of the present invention can be changed as appropriate depending on the polymer composition, it is preferably in the range of 110 to 140°C. In addition, the polyester referred to in the present invention means that at least 80 mol% of the constituent units are ethylene terephthalate or butylene terephthalate, and in addition to the above S component and the polyalkylene glycol component, other components are 10 mol% or less, preferably 5 mol% or less. The components may be copolymerized.

The fibers of the present invention can improve yarn strength, spinnability, high-order passability, dyeability, alkali resistance, light resistance, etc. by using modified polyester, and also have the effect of maintaining the shape of the fibers. In addition, by containing an appropriate amount of matting agent, the anti-transparent property can develop a milky luster.
A dry touch feeling can also be imparted. Furthermore, by combining it with a unique cross-sectional shape, it is possible to improve color development and clarity, and also to impart a new, soft and unique smooth texture.

The fibers of the present invention may contain well-known additives such as antioxidants, optical brighteners, flame retardants, ultraviolet absorbers, and the like, to the extent that they do not impede the effects of the present invention.

The fiber of the present invention may be filament-like or cotton-like, and the fineness is preferably in the range of 0, 5 to 10 denier, which is usually used for clothing, and the fiber is a fineness mix or a heat shrinkable mix. Alternatively, it can be used in combination with other fibers.

As explained above, the rectangular cross-section polyester fiber of the present invention has transparency properties, good dyeability, high yarn strength, excellent color development and clarity, milky luster, soft and unique It is suitable for high-grade woven and knitted fabrics, especially high-grade fabrics, that have a smooth and novel feel.

Furthermore, the same effect can be achieved by performing known bulking processing such as false twisting and fluid processing.

The rectangular cross-section polyester fiber of the present invention can be suitably produced by the following method.

FIG. 2 is a plan view showing an example of the shape of a polymer discharge hole of a spinneret for melt-spinning the fiber of the present invention. The polyester of the present invention is melt-spun in a conventional manner using a spinneret having the above-mentioned discharge holes, wound up while cooling and adding oil, and then stretched at a desired draw ratio. As another example, a composite fiber as shown in FIG. 3 is obtained by the method disclosed in Japanese Patent Application Laid-open No. 57-128218 previously proposed by the inventors, and the easily soluble polymer that hits the recesses is eluted. By this method, fibers having the cross section shown in FIG. 1(a) can be easily obtained.

[Example] The present invention will be specifically explained with reference to Examples below. Each measurement value in the examples was determined according to the following method.

A. Polyalkylene glycol component content The polymer was subjected to amine decomposition and then subjected to gas chromatography.

B. Determine the number of terminal groups per unit weight of polymerization degree by a commonly used method,
Calculated using the following formula.

Degree of polymerization = X106 Number of terminal groups (co/io6g) x average molecular weight C6 Light fastness Measured on a blue scale basis when photobleached according to JIS-L 1044 using a fade meter.

D, dyeable malachite green (trade name manufactured by Kanto Kagaku ■) 5% owf
, Acetic acid 0.5g/H, Sodium acetate 0.2g/α, Bath ratio 1
:100, the temperature was 120°C, and the solvent was water.

E8 color development property 8M color computer [manufactured by Suga Test Instruments ■] 5 or more fabrics with a constant exhaustion rate of black dye were stacked together and evaluated by the L value measured in a state where irradiation light was not transmitted. (Low value means high color development) F, vividness, glossiness, feel to the touch Fabrics dyed under certain dyeing conditions were sensory evaluated.

G, cross-sectional shape of polyester fiber It was measured and calculated from a cross-sectional photograph of the fiber.

H0 anti-transparency is measured using an 8M color computer [manufactured by Suga Test Instruments Co., Ltd.] by placing a white object and a black object behind the fabric. It was used as a measure of gender.

Example 1 Terephthalic acid (98.3 mol%) and dimethyl (
1.7 mol% of 5-sodium sulfo)isophthalic acid,
A polymer containing 2.3% by weight of titanium oxide with an average particle size of 0.5 microns and a maximum particle size of 2 microns (polymerization degree is 90-100 ) was melt-spun at a spinning temperature of 300° C. using a spinneret with a discharge hole shown in FIG. 2, and wound at a speed of 1600 m 2 /min. Subsequently, hot roll drawing was carried out at a drawing speed of 600 m/min, a heating roller of 90°C, and a drawing ratio such that the drawn yarn elongation was 30 ± 2%.
A drawn yarn of 5 denier 24 filaments was obtained. The cross-sectional shape of the fibers of the drawn yarn is a rectangular cross-section as shown in FIG. A of the fiber of the present invention) is 20.
5 microns, B is 12.5 microns and A/B is 1.64
, C is 7.0 microns, D is 2.8 microns, and D/C is 0.4, and the other experimental levels are A/B of 1.63 to 1.
73, and D/C was in the range of 0.4 to 0.8. These drawn yarns are used as warp yarns of 200t.
/m of twist and glue, and the weft was left as is, with a weave density of 110 warps/inch and weft 90 threads/inch, and a habutae was woven. Thread breakage based on the warp during weaving was as high as 35 times/io7m for the yarn used in Experiment 8 (comparative example), while it was less than 0.4 times/io7m for all other yarns used. .

Experiments 1 to 7 (invention) The fabric used had high yarn strength;
It had good dyeability, color development, and light fastness, had a milky luster, and had a new soft and smooth texture. In addition, the anti-transparent property was also good.

The fabric used in Experiment 8 (comparative example) had low yarn strength and insufficient color development. The fabric used in Experiment 9 (Comparative Example) had low dyeability, and the fabric used in Experiments N and 10 (Comparative Example) had poor light fastness.

(Left below) Example 2 Terephthalic acid (98 J mol%) and dimethyl (5 J mol%) were added as acid components.
-Polyester (degree of polymerization 91) made by copolymerizing 1.7 mol% of sodium sulfo)isophthalic acid and 2.0% by weight of polyethylene glycol with a molecular weight of 1000 as polyalkylene glycol, with an average particle size of 0.5 microns and a maximum particle size of 2. The polymer containing 2.3% by weight of micron titanium oxide was spun, drawn, and spun in the same manner as in Example 1, except that a spinneret with various dimensions and different dimensions was used to discharge the polymer containing 2.3% by weight of micron titanium oxide.
Weaving was carried out and evaluated. The results are shown in Table 2. The cross-sectional shapes of the fibers of the drawn yarn are rectangular in various shapes as shown in FIG. In actual device 15 (the present invention), A is 20.8 microns, B is 12.6 microns, A/B is 1.65, C is 7 microns, D is 4.2 microns, and D/C is 0. .60 and other experimental level A/B.

D/C had a cross-sectional shape as shown in Table 2.

The fabrics used in Experiments N, 12, N214 to ■6, and Ichi 18 (all of the present invention) were satisfactory in firmness and waist, had good color development, had a milky luster, and had a new soft and smooth texture. Met. Experiment Nh l I (comparative example) is A
/B was small (the firmness and stiffness were too strong, the color development was poor, and the soft feeling was also insufficient. Actual device 13 (comparative example) had a small D/C, poor color development, and lacked milky luster. In Experiments N and 17 (comparative example), the D/C was large, the color development was poor, the milky luster was insufficient, and there was no smooth texture.

Experiment N, 19 (comparative example) had a large A/B ratio and
I felt weak because my hips were lacking. Also, experiment N,
No. 19 had poor spinnability and poor yarn unwinding properties. In addition, the anti-transparent properties and dry touch feeling were also at a good level.

(Space below) Example 3 A polymer containing the polyester of Example 2 and titanium oxide in the content shown in Table 3 (composition is the same as in Example 1) was spun, stretched, and woven in the same manner as in Example 1. was conducted and evaluated. The results are shown in Table 3.

In Experiments N and 20 (comparative examples), the titanium oxide content was low, so the transparency, milky gloss, and dry touch feeling were poor. In addition, the smooth texture was also slightly poor.

Experiment N, 26 (comparative example) had anti-transparency, milky gloss,
Although the dry touch feeling was good, the tearing strength of the fabric was low due to low color development and low thread strength, and the quality was extremely poor and had no commercial value due to the large amount of fluff generated during weaving. Ta. In addition, the upper bound of the P material is large due to clogging of the transient layer during spinning, and yarn breakage occurs frequently.
It was impossible to perform stable spinning for more than 0 hours.

Experiments N, 21 to -25, which are examples of the present invention, have color development,
The transparency, milky gloss, and dry touch were satisfactory. However, in Experiment 25, a slight decrease in tearing strength was observed, which was considered to be due to a decrease in yarn strength. In addition, in all levels of the experiment, the cross-sectional shape of the fibers of the drawn yarn was such that A/B was in the range of 1.68 to 1.70, and D/
C was in the range of 0.4-0.5. Also, experiment N, 2
At all levels other than 0, the fabric had a soft and smooth texture.

(Leaving space below) Example 4 Using the polymer of Example 2 and using a spinneret with an O-shaped, Y-shaped, Japanese cedar, diagonal, or H-shaped discharge hole,
Spinning, drawing and weaving were carried out in the same manner as in Example 1 and evaluated. Table 4 shows the cross-sectional shape of the obtained fibers and the evaluation results of the woven fabric.

The fabrics used in Experiments N127 to N31 (comparative examples) had poor color development and had the drawbacks shown in the table, making them unsuitable for application to high-grade fabrics. In addition, the anti-transparent property was good at all levels without much difference.

(The following is a blank space) [Effects of the Invention The rectangular cross-section polyester fiber of the present invention has the following effects.

(1) The constituting polyester contains 0.7 to 2.4 mol% of an isophthalic acid component containing a metal sulfonate group,
Since it is a modified polyester copolymerized with 0.2 to 10% by weight of a polyalkylene glycol component having a molecular weight of 90 to 1000, it has high yarn strength and is excellent in dyeability and light fastness of dyed products.

(2) The cross-sectional shape of the fiber is rectangular as a whole, and the outer periphery has irregularities, so it has a soft touch compared to round or triangular cross-section yarns, and the reflected light is spread over a wide angle. Because it is diffusely reflected, it has an elegant luster, excellent color development and clarity, and creates a high-class image.

(3) Gives the woven or knitted fabric appropriate firmness and elasticity, and has good drapability.

(4) The synergistic effect of the modified polyester with a specific amount of matting agent and the specific cross-sectional shape improves the color development and clarity of the woven or knitted fabric, develops an elegant milky luster, and creates a unique flat-touch feel. Gives a smooth new texture.

(5) It is a fiber suitable for use in high-grade woven and knitted fabrics, especially high-grade fabrics.

It has excellent effects such as

[Brief explanation of drawings]

FIGS. 1A and 1B are cross-sectional views of typical fibers in the present invention. FIG. 2 is a plan view showing an example of the shape of a polymer discharge hole of a spinneret for producing the fiber of the present invention. FIG. 3 is a cross-sectional view of a fiber before alkali treatment obtained by a composite spinning method for producing the fiber of the present invention. FIGS. 4 to 10 are cross-sectional views showing an example of a conventional fiber having unevenness. Patent applicant Toshi Co., Ltd. (A) υ) Figure 1 Figure 6 Figure 7 Figure 2 Figure 3 Figure 8 Figure 9 Figure 10 Figure 4 Figure 5

Claims (1)

[Claims] Copolymerization of an isophthalic acid component containing a metal sulfonate group from 0.7 to 2.4 mol% based on the total dicarboxylic acid component and a polyalkylene glycol component having a molecular weight of 90 to 6000 from 0.2 to 10% by weight based on the polyester. The fiber is made of modified polyester containing 1.3% by weight or more and 8.0% by weight or less of a matting agent, and the cross-sectional shape of the fiber is rectangular as a whole, and the length of the long side of the rectangular cross-section is As A,
When the length of the short side is B, A/B is in the range of 1.2 to 2.2, and there are 1 to 4 recesses on the long side surface and 1 to 3 recesses on the short side surface. A polyester fiber having a rectangular cross section, wherein D/C is in the range of 0.2 to 1.0, where C is the entrance width of the recess and D is the depth thereof.