JP2023149539A - Polyester fiber and manufacturing method thereof - Google Patents

Abstract

[Problem] To provide a fine-grained polyester fiber that suppresses glare when made into a woven or knitted fabric using fine-grained polyester fiber, and which has both a natural luster and a soft texture even when it is a fine-grained fiber, and a method for producing the same. do. [Solution] A polyester fiber with a single fiber fineness of 0.20 dtex or more and 0.80 dtex or less, containing 0.10% by mass or more of inorganic particles with an average particle diameter of 0.60 μm or more and 1.00 μm or less, 0.50 dtex or more % by mass or less, the flatness of the cross section is 3 or more and 10 or less, and the fiber surface has concave portions of 0.05 μm2 or more and 0.20 μm2 or less of 5 x 103 pieces/mm2 or more and 5.0 x 105 pieces/mm2 Polyester fibers with: [Selection diagram] None

Description

The present invention relates to a polyester fiber and a method for producing the same.

Among synthetic fibers, polyester fibers are inexpensive and have excellent physical properties, so they are widely used in both clothing and industrial applications. For clothing applications, in addition to the material's inherent properties of quick drying and wrinkle resistance, various improvements are being considered to improve functionality, such as adding moisture absorption and antibacterial properties through post-processing using chemicals, as well as changes in the physical shape of the fibers. In order to improve the functionality of fabrics, improving the softness of the texture of fabrics by making single fibers finer is also being considered.

As a means for making single fibers finer by spinning technology, Patent Document 1 discloses a method for obtaining fineness polyester filaments with a single fiber fineness of 0.7 dtex class by direct spinning. In addition to the direct spinning method, a method is known in which the sea component is eluted after spinning a sea-island composite fiber in which the poorly soluble component is an island component and the easily soluble component is a sea component. With this method, it is possible to obtain ultrafine yarn with a single fiber diameter on the order of nanometers, and it is also used for applications such as artificial leather and wiping cloth. Patent Document 2 discloses a method in which polyethylene terephthalate fiber is used as an island component, polyester copolymerized with 5-sodium sulfoisophthalic acid and diethylene glycol is used as a sea component, and fibers having an average single fiber diameter of 10 to 1500 nm are obtained by alkaline sea removal. It is shown.

In addition to sea-island composite fibers, Patent Document 3 discloses a split-type fiber cross section as a method for making the fineness of composite fibers finer by post-elution using easily eluted components. A method for obtaining a 0.2 dtex irregular cross-section yarn is disclosed.

As the single fiber fineness becomes finer, the number of single fibers increases for the same filament fineness and spun yarn count, so the apparent coloring property decreases due to an increase in diffuse reflection. However, in Patent Document 4, inorganic A method has been shown in which particles are generated, turned into fibers, and then eluted to cause the particles to fall off, forming high-density recesses on the fiber surface to darken the color.

JP2004-204431A Japanese Patent Application Publication No. 2014-101613 Patent No. 3715375 Japanese Patent Application Publication No. 2019-44281

In fine-grained polyester fibers obtained by the means described in Patent Documents 1 to 3, etc., diffuse reflection on the fiber surface increases as the number of single fibers constituting the fiber bundle increases compared to those with thicker fineness. As a result, in addition to a decrease in apparent color development, undesirable textures may be produced, such as an emphasis on the glare characteristic of synthetic fibers and flickering on the surface of the fabric. As in Patent Document 4, by forming a high density of recesses, a deep coloring effect can be obtained and regular reflection can be suppressed, and the above-mentioned effect of suppressing glare can be obtained, but since this method forms a high density of recesses, Rather, it had a matte texture with a loss of gloss, and the texture of the fabric surface had not been improved.

The purpose of the present invention is to suppress glare when woven or knitted fabrics are made using fine-grained polyester fibers, and to produce polyester-based fine-grained fibers that have both a natural luster and a soft texture even when the fine-grained fibers are used. The purpose is to provide a method.

The present invention has the following configuration to solve the above problems.

(1) Polyester fibers with a single fiber fineness of 0.20 dtex or more and 0.80 dtex or less, containing 0.10% by mass or more and 0.50% by mass of inorganic particles with an average particle diameter of 0.60 μm or more and 1.00 μm or less % or less, the flatness of the cross section is 3 or more and 10 or less, and the fiber surface has concavities of 0.05 μm ² or more and 0.20 μm ² or less 5 × 10 ³ / mm ² or more, 5.0 × 10 Polyester fiber having ⁵ fibers/mm2 or ^less .

(2) A woven or knitted fabric containing 40% by mass or more of the above polyester fibers.

(3) A sea-island type composite fiber having a cross section in which the easily eluted component is a sea and the poorly eluted component is an island, and the easily eluted component is divided into multiple pieces, with the easily eluted component being an island. A conjugate fiber selected from split-type conjugate fibers having arranged cross sections, the easily eluting component of the conjugate fiber containing polyester as the hardly eluting component is eluted, and the polyester as the hardly eluting component is eluted. The method for producing the above-mentioned polyester fiber, characterized by reducing the weight by 15% by mass or more.

According to the present invention, it is possible to provide a textile product that has a good soft feel and has a natural luster with suppressed glare even if it is a fine fiber.

FIG. 1 is a schematic diagram showing one aspect of the fiber cross-sectional structure of a three-part split type composite short fiber. FIG. 2 is a schematic diagram showing one aspect of the fiber cross-sectional structure of a two-part split-type conjugate short fiber. FIG. 3 is a schematic diagram showing one aspect of the fiber cross-sectional structure of a four-part split type composite staple fiber. FIG. 4 is a schematic diagram showing one aspect of the shape of the discharge hole of the spinneret.

The present invention will be explained in detail below. The single fiber fineness of the polyester fiber of the present invention is 0.20 dtex or more, preferably 0.40 dtex or more, and 0.80 dtex or less, preferably 0.70 dtex or less. By being 0.20 dtex or more, when made into a fiber bundle, the number of constituent single fibers will be appropriate, and when made into a woven or knitted fabric, diffused reflection on the fabric surface will be suppressed, suppressing flickering and giving a natural luster. can. Furthermore, by setting the dtex to 0.80 dtex or less, not only a soft texture can be obtained, but also the fluff that appears on the surface of the fabric when it is woven or knitted will have a peach touch, giving it a smooth feel.

The polyester fiber used in the present invention can be obtained by directly spinning a single-component polymer, or by spinning a composite fiber consisting of an easily soluble component and a poorly soluble component, and then eluting the easily soluble component. It is also possible to take other methods. Composite fibers can take the form of sea-island composite fibers, which have a cross section in which the easily eluted component is a sea and the poorly eluted component is an island (the number of islands may be plural), or the conjugate fiber is a conjugate fiber that has a sea-island shape in which the easily eluted component is a sea, and the poorly eluted component is an island (the number of islands may be plural); In addition to split-type composite fibers having a cross section arranged so that the easily eluted component is divided into a plurality of parts, post-elution type irregularly shaped fibers that obtain a hollow or irregularly shaped structure by elution of the easily eluted component can be used. is also possible. It is possible to avoid troubles such as yarn breakage in the raw yarn manufacturing process and spinning processing process, and the process to reduce the amount of poorly soluble components can be performed at the same time as the leaching process of easily soluble components. It is preferable to use a conjugate fiber made of a hardly eluting component, and more preferably a split type conjugate fiber, in which elution proceeds quickly even at a low ratio of easily eluting components, and fine fibers can be obtained relatively easily.

In the case of using composite fibers, the ratio of the easily leached component to the total mass of the composite fibers is not particularly limited as long as weight reduction processing is possible, but it is preferably 40% by mass or less, and more preferably 25% by mass or less. By controlling the content to 40% by mass or less, the burden of chemicals, utilities, and wastewater treatment in the subsequent elution process can be reduced, and fibers with excellent productivity can be obtained. Further, the ratio of easily eluted components is preferably 10% by mass or more, more preferably 15% by mass or more. By setting the content to 10% by mass or more, it is possible to avoid poor elution by avoiding island merging during the spinning process and ensuring a certain amount of area where easily eluted components are exposed on the fiber surface during the elution process. Become.

Examples of materials constituting the polyester fiber in the present invention include, but are not limited to, polymers such as polyalkylene terephthalates such as polyethylene terephthalate, polybutylene terephthalate, and polytrimethylene terephthalate, and copolymers thereof. Instead, it may be a copolymer obtained by further copolymerizing the above polymer with isophthalic acid sulfonate, adipic acid, isophthalic acid, polyethylene glycol, etc., or a modified polyester obtained by blending polyethylene glycol.

In addition, when making a composite fiber consisting of a poorly eluted component and an easily leached component, the above-mentioned materials can be used as the leached component, and the easily leached component has difficulty in solubility in alkali or hot water. It is not particularly limited as long as it is higher than the eluting component and can be melt-spun, and copolymers of polyalkylene terephthalates such as polyethylene terephthalate, polybutylene terephthalate, and polytrimethylene terephthalate, and polyesters such as polylactic acid (copolymers) may be used. In addition to polymers, polyamide, polystyrene and its copolymers, polyethylene, polyvinyl alcohol, etc. can be used. As the hardly leached component, polyethylene terephthalate, which has excellent strength and quick-drying properties and is available at low cost, is preferable.As the easily leached component, it is preferable to use polyethylene terephthalate, which is easily leached in a general-purpose alkaline aqueous solution and is suitable for fusion between composite fibers. Polyethylene terephthalate, which is copolymerized with sodium 5-sulfoisophthalate and/or polyethylene glycol, is preferred because it is less likely to cause such problems and has good passability through higher processing. More preferably, sodium 5-sulfoisophthalate is copolymerized with 5 mol% to 15 mol% of the total dicarboxylic acids, and sodium 5-sulfoisophthalate is copolymerized with 5 mol% to 15 mol% of the total dicarboxylic acids, in addition to the weight average molecular weight. Polyethylene terephthalate copolymerized with 500 to 3000 polyethylene glycol in a range of 5% by mass to 15% by mass is preferred. These materials can be melt-spun into polyester fibers using conventional methods, and can be used singly or in combination of two or more.

The form of the polyester fiber in the present invention may be a filament or a staple. Note that the concept of filament includes drawn yarn and various twisted yarns. The type of twisted yarn is not particularly limited, and examples thereof include false-twisted processed yarn, false-twisted fused yarn, and medium-strong twisted yarn. In the case of staples, there is no particular restriction on the fiber length, and fibers with a fiber length suitable for the type of fibers to be combined can be used. However, from the viewpoint of aligning the fiber direction and easily obtaining a glossy appearance, the longer fiber length is used. The fiber length is preferably 38 mm or more, more preferably 51 mm or more.

The cross section of a single fiber of the polyester fiber in the present invention (the cross section in the direction perpendicular to the fiber axis direction) is flat, and its flatness is 3 to 10, preferably 4 to 8. Flatness is measured by the method described below, and is expressed as the ratio of the longest axis length to the shortest axis length in the cross section of a single fiber (longest axis length/shortest axis length), and the longest axis length is the maximum length in the cross section of a single fiber. The shortest axis length is the maximum diameter while maintaining a right angle to the longest axis. Because the single fiber cross section is flat, the reflective surfaces on the surface of the fiber bundle are aligned, increasing the proportion of specularly reflected light even when the fibers are fine, and when made into a fabric, it can give a gloss that suppresses flicker. In particular, when there are recesses described below, a characteristic natural glossiness can be obtained. At this time, when the flatness is 3 or more, the above-mentioned alignment of the fiber bundle surfaces is likely to occur, the intensity of specularly reflected light increases, and sufficient gloss can be obtained, while when the flatness is 10 or less, In addition to suppressing excessive specular reflection that can lead to shine and glare when made into a fabric, it suppresses the overlap of single fibers when made into a fiber bundle, maintains bulk when made into a textile product, and further improves the fabric's appearance. It can give you harikoshi. As long as the flatness is within the above range, the shape of the single fiber cross section is not particularly limited, and multi-leaf cross sections, array types, hollow types, etc. can be adopted, depending on the texture and functionality required by the application. It can be selected as appropriate. The flatness can be adjusted by a conventional method, and in addition to appropriately selecting the shape of the discharge hole of the spinneret, in the case of a composite fiber, it can be adjusted as appropriate by designing the cross-sectional shape of the single fiber.

The polyester fiber of the present invention contains inorganic particles, and the material thereof is not particularly limited, but titanium oxide, zinc oxide, silicon oxide, magnesium oxide, zirconium oxide, aluminum oxide, calcium carbonate, etc. can be used alone, Alternatively, they can be used in combination. Among these, titanium oxide, which has good dispersibility in polyester polymers and excellent thread-spinning properties, is preferably used. The method of dispersing the inorganic particles into the polyester fibers is not particularly limited, but a method of kneading and adding them in the polymerization process can be used.

The average particle size of the inorganic particles is measured by the method described below, and is the particle size in an aggregated state existing in the polyester fiber, that is, the secondary particle size, and the average particle size of the inorganic particles is It is 0.60 μm or more and 1.00 μm or less. When the diameter is 0.60 μm or more, the inorganic particles fall off during the alkali weight reduction process described below, thereby forming concave portions of an appropriate size on the fiber surface and giving a natural luster. Moreover, by having a diameter of 1.00 μm or less, troubles of thread breakage in the yarn manufacturing process, spinning process, etc. can be suppressed, and excellent workability can be obtained. Furthermore, the presence of particles in this range on the fiber surface layer makes it possible to suppress specular reflection on the fiber surface or inside the fiber even if the fiber has the above flatness due to scattering of incident light. The average particle diameter of the inorganic particles varies depending on the primary particle diameter of the inorganic particles themselves used, the cohesiveness in the fiber manufacturing process, and the like. Therefore, as a means of adjusting the average particle size of inorganic particles to fall within the above range, in addition to selecting the average particle size of the inorganic particles to be used, using inorganic particles whose surfaces have been hydrophilized can prevent agglomeration. The particle dispersion conditions can be appropriately adjusted by suppressing the dispersion or adjusting the stirring conditions when dispersing inorganic particles in a solvent, polymer, etc. Examples of preferably used inorganic particles include titanium oxide such as TA-100 (average particle size 0.60 μm, catalog value, product form: dispersion) manufactured by Fuji Titanium Industries, Ltd., and TA-300 (average particle size 0.58 μm). , catalog value, product form: dispersion) is preferably used.

The proportion of the inorganic particles contained in the polyester fiber of the present invention is 0.10% by mass or more, preferably 0.20% by mass or more, and 0.50% by mass or more, when the entire polyester fiber is 100% by mass. It is not more than 0.40% by mass, preferably not more than 0.40% by mass. By having a content of 0.10% by mass or more, it is possible to form recesses with sufficient density during the weight reduction process described below, and it is also possible to suppress the reflected light on the fiber surface and inside, thereby reducing glare. It can be suppressed appropriately. In addition, by setting the content to 0.50% by mass or less, troubles such as yarn breakage in the spinning process, spinning process, etc. and scum generation due to shedding of the inorganic particles can be suppressed, and excellent workability can be obtained. By suppressing excessive light scattering by the inorganic particles and suppressing excessive formation of recesses after weight reduction, dull texture can be avoided. The inorganic particles may be uniformly dispersed inside the fiber, or the content may be partially different. Preferably, the inorganic particles described above are present on the surface. The cross-sectional form of the fiber having such a structure may include a core-sheath structure in which at least the sheath portion contains the inorganic particles, a structure in which two or more components are laminated in a layered structure, or a hollow structure. be.

The polyester fiber of the present invention includes a concave portion of 0.05 μm ² or more and 0.20 μm ² or less on the fiber surface. When the area of the concave portion is 0.05 μm ² or more, it is possible to obtain the effect of suppressing diffuse reflection of incident light and suppress flickering, and when it is 0.20 μm ² or less, it can provide a moderate gloss when made into a woven or knitted fabric. can give. In addition, the shape of the recess is not particularly limited as long as it has the above-mentioned area, and may be formed in a circle, an ellipse, or a striped shape. A circular or oval shape is preferable from the viewpoint of avoiding a squeaky feeling when worn. The circular and elliptical shapes shown on the left do not need to be strictly circular or elliptical, and may be approximately circular or elliptical.

Further, the density of the recesses of 0.05 μm ² or more and 0.20 μm ² or less in the present invention is 5×10 ³ or more/mm ² or more and 5.0×10 ⁵ /mm ² or less, preferably 1 .0×10 ⁴ pieces/mm ² or more and 2.0×10 ⁵ pieces/mm ² or less, more preferably 5.0×10 ⁴ pieces/mm ² or more and 1.0×10 ⁵ pieces/mm ² or less. be. When the density of the recesses on the fiber surface is 5×10 ³ pieces/mm ² or more, the above-mentioned effect of suppressing diffused reflection can be sufficiently obtained, and glare and flickering can be suppressed. In addition, by setting the number to 5.0×10 ⁵ pieces/mm ² or less, it is possible to suppress the dull feeling caused by the unevenness of the fiber surface when it is made into a textile product, and to avoid loss of clarity of color development. .

The method for forming the recesses is not particularly limited, but it is possible to develop the recesses by reducing the amount of polyester fiber containing the inorganic particles by the method described below and causing the contained inorganic particles to fall off. be. Conventional methods can be used to reduce the weight of polyester fibers, such as alkaline reduction in which polyester is hydrolyzed with a high-temperature alkaline aqueous solution, dissolution in a solvent that can dissolve polyester fibers, or emery treatment. Examples include a method of surface polishing using a roll or the like. Among these, alkali reduction is preferably used as it is possible to more uniformly develop the recesses by reducing the entire surface of the fiber, and the chemicals used are inexpensive and the recovery process is relatively easy. The method of alkali weight loss is not particularly limited, and bath methods include cheese weight loss, beam weight loss, and jet dyeing machine weight loss, as well as a continuous steam method in which aqueous alkali solution is applied, squeezed, and then steam treated. etc. can be adopted. Above all, in addition to achieving high productivity through continuous processing, it suppresses the unraveling of single fibers due to contact between fabrics, friction with liquid during bath treatment, and contact between fibers, and improves surface quality when fabricated into a fiber structure. A continuous steam method is preferably used from the viewpoint of maintaining the temperature.

A sea-island type composite fiber having a cross section in which the easily eluted component is a sea and the poorly eluted component is an island, and the easily eluted component is arranged so that the easily eluted component is divided into a plurality of pieces. When using a conjugate fiber selected from split-type conjugate fibers having a cross section and containing polyester as a poorly soluble component, the easily soluble component of the conjugate fiber is eluted, and the conjugate fiber is The amount of the component polyester is reduced, and the above-mentioned reduction processing can also be performed after elution of the easily eluted component, but from the viewpoint of production efficiency, it is necessary to elute the easily eluted component and reduce the amount of the hardly eluted component. It is preferable to perform both at the same time. In the case of forming composite fibers, the flatness of the islands in a cross section perpendicular to the fiber axis direction is preferably 3 or more and 10 or less, more preferably 4 to 8. The flatness can be measured in accordance with the measurement of the flatness of polyester fibers described below, in which case the diameter in the cross section of the single fiber is read as the diameter of the island in the cross section of the composite fiber. Usually, the flatness of the islands is approximately the same value as the flatness of the polyester fiber after elution of easily eluted components and weight loss.

The weight loss rate of the polyester fiber as the hardly eluting component is preferably 2% by mass or more and 15% by mass or less, more preferably 4% by mass, based on the mass of the polyester fiber as the hardly eluting component. The content is 13% by mass or less, more preferably 6% by mass or more and 11% by mass or less. By setting the amount to 2% by mass or more, in addition to sufficient formation of the recesses, it is possible to improve softness by securing voids between fibers, and the fiber surface becomes smooth due to the weight loss. This makes it easier to obtain a more uniform gloss. Further, by setting the content to 15% by mass or less, excessive damage to the polyester fibers can be avoided and the strength required for processing and use of woven or knitted fabrics can be ensured.

In addition, when using the above-mentioned composite fiber, a polyester fiber containing a hardly eluting component can be obtained by eluting the easily eluting component. The following polyester fibers can be used. In addition, in order to adjust the single fiber fineness of the finally obtained polyester fiber of the present invention to the range specified by the present invention, the fineness design and weight loss rate during direct spinning should be adjusted, and when making it into composite fiber, can be adjusted as appropriate by adjusting its fineness, the composite ratio of the poorly eluted component forming the islands, the number of islands, and the weight loss rate.

The conditions for the alkali weight loss include, in the case of composite fibers with easily eluting components, in accordance with the composition and elution rate of the easily eluting components used, and also taking into account the composition and weight loss rate of the poorly eluting components. It can be adjusted within a range that provides a predetermined weight loss rate. Examples of alkaline chemicals that can be used include sodium hydroxide, potassium hydroxide, sodium carbonate, potassium carbonate, and tetramethylammonium, but sodium hydroxide, which is industrially easily available and inexpensive, is preferably used. The alkali concentration can be set within a range that provides the desired weight loss rate; in the case of a bath method, it is 1 g/L or more and 20 g/L or less, and in the case of a continuous steam method, it is 20 g/L or more and 100 g/L or less. It is possible to set it with . Further, in the bath method, the treatment temperature can be set at, for example, 80° C. or higher and 120° C. or lower. By setting the temperature to 80°C or higher, sufficient elution and weight loss rates can be achieved, and the possibility of poor elution and weight loss is extremely reduced. On the other hand, by setting the temperature to 120°C or lower, a moderate rate of weight loss can be achieved and weight loss between single fibers can be achieved. This is preferable in that variations are less likely to occur. With the continuous steam method, in addition to processing at 100°C using a normal pressure steamer, it is also possible to process at temperatures higher than 100°C using a high-pressure steam device or superheated steam. From this point of view, treatment using a normal pressure steamer is preferably used. Although the processing time can be appropriately selected depending on the weight loss rate for each material, it is preferably 1 minute or more and 60 minutes or less.

The polyester fiber of the present invention can be used alone or in combination with other fibers. The type of fibers to be combined may be synthetic fibers or natural fibers, but when performing alkali weight loss as a means of weight loss, it is recommended to use acrylic fibers with low alkali resistance in combination. Please be careful as it may cause yellowing or brittleness. The blending ratio of the polyester fiber of the present invention when used in combination with other fibers is not particularly limited, but from the viewpoint of maintaining soft texture and gloss, the blending ratio may be 40% by mass or more, preferably 60% by mass or more. 80% by mass or less is preferable from the viewpoint of achieving the desired properties and also exhibiting the characteristics of the fibers to be combined.

Examples of synthetic fibers that can be used in combination with the polyester fibers of the present invention include polyamide fibers such as nylon 6 fibers and nylon 66 fibers, acrylic fibers containing polyacrylonitrile as a main component, polyethylene fibers, and polypropylene fibers. Synthetic fibers such as polyolefin fibers such as polyolefin fibers and polyvinyl chloride fibers may be mentioned. Further, it is also possible to use staple-shaped fibers made of the material constituting the aforementioned polyester filament. Among them, aromatic polyester fibers (polyethylene terephthalate fiber, copolymerized polyethylene terephthalate fiber, polytrimethylene terephthalate fiber, polybutylene terephthalate fiber, etc.), which have excellent physical properties and are relatively inexpensive, are preferably used.

As natural fibers that can be used in combination with the polyester fibers of the present invention, cellulose fibers, protein fibers such as wool and silk, etc. can be used, and the cellulose fibers include cotton, linen, pulp, etc. Natural cellulose fibers such as Viscose rayon, regenerated cellulose fibers such as Cupra, etc. can be used. From the viewpoint of water absorption and cost suitable for clothing applications, cellulose fibers are preferred, and among them, cotton is more preferably used because it can provide the good feel of natural fibers.

The fiber bundle using the polyester fiber of the present invention can be used not only as a multifilament alone but also as a spun yarn, such as ring spun yarn, compact yarn, MVS yarn, long and short composite yarn, short and short composite yarn, and other known fiber bundles. It is possible to use it as a spun yarn by the following spinning method. When using long and short composite yarns or short and short composite yarns, it is preferable to arrange the polyester fiber of the present invention on the sheath side from the viewpoint of making better use of texture and gloss. The twist coefficient in the case of forming a spun yarn can be set as appropriate, and is preferably 3.0 or more and 4.0 or less. When it is 4.0 or less, a texture that takes advantage of softness can be obtained, and when it is 3.0 or more, fluffing of the single fibers is suppressed and glossiness can be maintained.

The polyester fiber of the present invention can be suitably used as a fiber structure, but when used as a woven or knitted fabric, its structure is not particularly limited, and in the case of a woven fabric, it can be a plain weave, a twill weave, a satin weave, a modified plain weave, Examples include variable oblique weave, variable satin weave, variable weave, patterned weave, single layer weave, double weave, multiple weave, warp pile weave, weft pile weave, and interlocking weave. In the case of knitted fabrics, circular knitting, weft knitting, warp knitting (including tricot knitting and raschel knitting), pile knitting, flat knitting, jersey knitting, rib knitting, smooth knitting (double-sided knitting), elastic knitting, pearl knitting, and denby knitting are available. Examples include tissue, cord tissue, atlas tissue, chain tissue, and insertion tissue. Woven fabrics are preferable because the structure of the fiber structure is dense and can enhance the gloss and smoothness of the surface of the fabric. Appropriate restraint of the fiber bundles suppresses the unraveling of single fibers and the occurrence of fluff, and maintains gloss. From the viewpoint of ease of use, a plain weave structure is more preferable.

Further, a textile product using the polyester fiber of the present invention may be subjected to press processing such as calendar processing. By pressing, a surface along the longest axis of the flat cross section appears on the surface of the textile product, so it is possible to obtain a more uniform gloss, and the degree of gloss development can be adjusted by pressing conditions. . In particular, it can be suitably used in textile products having a low blending ratio of polyester fibers of the present invention. In addition, by appropriately pressing the fibers together, it is possible to prevent the single fibers in the fiber bundle from being dispersed due to physical shocks such as wearing or washing, and it is possible to improve the durability of the glossy appearance. On the other hand, if the calender treatment is too strong, glare may occur, so it is preferable to select conditions appropriately.

Fiber products using the polyester fibers of the present invention can also be subjected to a fluffing process by a known method. Fuzzing and pilling may worsen in textile products using fine-grained fibers, but these can be suppressed by performing an appropriate pilling process, and by improving the surface smoothness, it becomes more elegant. It can give a glossy feel. On the other hand, it is also possible to leave the fluff of the fine fibers and make the surface touch smooth by not performing the firing at all or by performing the firing under weak conditions.

Preferable examples of the above-mentioned fiber products include woven and knitted fabrics, particularly woven and knitted fabrics containing 40% by mass or more of polyester fibers. Such woven or knitted fabrics are particularly suitable for use in blouses and dress shirts because they suppress glare and have both a natural luster and a soft texture even if they are made of fine-grained fibers.

The present invention is not limited to the following examples. In addition, performance evaluation in Examples was performed according to the following method.

(1) Single fiber fineness The single fiber fineness of polyester fibers was measured by the method described in JIS L1013:2021 for filaments and JIS L1015:2021 for staples (short fibers). For fibrous structures such as spun yarn and woven or knitted fabrics, if it is a filament, it is measured using a decomposed yarn according to method 8.3.1B of JIS L1013:2021, and if it is a staple, a single fiber is taken out from the decomposed yarn and measured using JIS L1013:2021 method 8.3.1B. Measured by method 8.5.1B of L1015:2021.

In addition, the single fiber fineness before weight loss in the woven and knitted fabrics before elution and weight loss in the table is the single fiber fineness of the composite fiber measured by the above method (single fiber fineness of the composite fiber before removal of easily eluted components and before weight loss processing) is multiplied by the composition ratio of the poorly eluted component, and divided by the number of islands or the number of splits in the case of sea-island fibers or split fibers (hereinafter, the value of the polyester fiber obtained when the easily leached components of the composite fiber are removed). The single fiber fineness is sometimes referred to as "theoretical single fiber fineness."

(2) Weight loss rate From the single fiber fineness before weight loss and the single fiber fineness after weight loss measured in (1) above, the weight loss rate in filaments and staples was calculated using the following formula.
Weight loss rate (mass%) = (1 - single fiber fineness after weight loss/single fiber fineness before weight loss) x 100

In the case of a composite fiber containing an easily eluted component, the theoretical single fiber fineness of the woven or knitted fabric before elution and weight loss explained in (1) above was substituted for the single fiber fineness before weight loss.

In the case of fibrous structures such as fabrics, measurements were performed using the following method.

A 5×20 cm area of the fibrous structure is cut out, and the mass of the fabric before weight reduction processing (in the case of using composite fibers, before removal of easily eluted components) is measured.

A mark was made on a 5 x 20 cm area of the fiber structure, and after weight reduction processing, the fabric was cut out along the mark, and the weight loss rate was calculated from the mass after weight reduction processing according to the following formula.
Weight loss rate (mass %) = Mass after weight loss processing ÷ (mass before weight loss processing x Mixing ratio of composite fiber x Ratio of poorly soluble components) x 100

In addition, in the above formula, when a single fiber is used instead of a composite fiber, the composite fiber is read as a single fiber, and 1 is substituted for the ratio of the hardly soluble component.

(3) Average particle diameter of inorganic particles 10 single fibers were randomly collected and cut perpendicular to the fiber direction using a single-edged razor to prepare a sample. Photographs are taken using a microscope (SEM, Hitachi TM3030 Plus Miniscope) at a magnification of 2000 times to observe secondary particles present in the fibers. The aggregated secondary particles are regarded as one particle, and the maximum diameter thereof is defined as the particle diameter. The average value of the particle diameters of 100 observed inorganic particles was taken as the average particle diameter of the inorganic particles.

(4) Flatness 10 single fibers were randomly collected and cut perpendicularly to the fiber direction using a single-edged razor to prepare a sample, and a cross section of the single fibers was taken in a direction perpendicular to the fiber axis direction. (Cross section) was photographed at a magnification of 500 times using a scanning electron microscope (SEM, Hitachi TM3030 Plus Miniscope). The ratio of the longest axis length to the shortest axis length, where the maximum diameter in the cross section of the photographed single fiber is the longest axis length, and the longest axis is kept perpendicular to the longest axis, and the maximum diameter is the shortest axis length. (Longest axis length/Shortest axis length) was determined, and the average value of the values calculated for 50 single fibers was taken as the flatness.

(5) Size and number of concavities on the fiber surface 10 single fibers of polyester fibers were randomly sampled, and the surface of the single fibers was examined at a magnification of 2000 times using a scanning electron microscope (SEM, Hitachi TM3030 Plus Miniscope). Photographed at. Ten areas of 5 μm x 2 μm are randomly set from the surface of the single fiber, and among the recesses existing in this area, the number of recesses that are 0.05 μm ² or more and 0.20 μm ² or less is counted. The average value measured for 10 single fibers was converted into the number of recesses per 1 mm ² .

(6) Fiber mixture ratio Measurement was performed using the method described in JIS L1030-2:2012 Fiber mixture ratio.

(7) Fabric density Measurement was performed using the method described in JIS L1096:2020.

(8) Texture The texture was evaluated by sensory evaluation as shown below. If it is a fibrous structure such as a woven or knitted fabric, the evaluation was performed on the actual product, if it was a fiber bundle such as a filament or spun yarn, a tubular knitted fabric was prepared and evaluated, and if it was a staple, it was prepared using a known method. A tubular knitted fabric was produced from the spun yarn and evaluated. The tube knitted fabric was knitted using a tube knitting machine (NCR-ES, 27G manufactured by Eiko Sangyo). The above tubular knitted fabric may be produced using the polyester fiber of the present invention, or the polyester fiber of the present invention may be obtained by subjecting the produced tubular knitted fabric to weight loss processing as described above. good. Texture was evaluated using the following criteria.

(Softness)
◎ (very good) is the fabric that has low resistance when bent and has drapability; ○ (good) is the fabric that has flexibility but has a slight stiffness; the fabric has strong elasticity and drapability Those with poor quality were evaluated as △ (slightly poor), and those with a rough texture and a strong feeling of resistance when gripping the fabric were evaluated as × (poor).

(touch)
◎ (very good) has a peach-touch feel made of ultra-fine fibers, is smooth and has little resistance to the touch, ○ (good) has a brushed feel and feels smooth, and has no resistance or squeaks to the touch. If the surface was rough, it was rated as △ (slightly poor), and if the surface felt rough and rough, it was rated as × (poor).

(9) Glossiness The glossiness was evaluated by sensory evaluation using the sample used for the texture evaluation in (8). The cylindrical knitted fabric produced in (8) above was evaluated for glossiness when viewed from an angle of 45° under a D65 light source in a light source booth (manufactured by X-Light Co., Ltd., SPECTRALIGHT QC) using the following criteria.

◎ (very good) for those that do not have glare or flicker and have an elegant silk-like luster, ○ (good) for those that are not as good as ◎ but have a glossy feel and some flickering. △ (slightly poor) for those that feel shiny due to strong light or have a flickering appearance, or on the other hand, those that have a weak gloss or dull appearance, and those that have a strong shine or a powdery and dull appearance. Items were judged as × (defective).

[Example 1]
100 parts by mass of dimethyl terephthalic acid, 75 parts by mass of ethylene glycol slurry containing 0.5% by mass of TA-100 manufactured by Fuji Titanium Industries Co., Ltd. (average particle size 0.60 μm) as titanium oxide, and 0.05 parts by mass of magnesium acetate as a reaction catalyst. 1 part and 0.04 parts by mass of antimony oxide were charged into a transesterification can, and gradually heated from 150°C to 250°C under a nitrogen atmosphere to carry out the transesterification reaction while extracting the methanol produced. 0.05 part by mass was added, and then the temperature was raised to 280° C. while gradually reducing the pressure and polymerization was carried out for 2 hours to obtain titanium oxide-containing polyester (polyethylene terephthalate) chips. The titanium oxide content was 0.27% by mass based on the produced polyester. The titanium oxide-containing polyester is used as a hardly eluting component, and polyethylene terephthalate obtained by copolymerizing 8 mol% of sodium 5-sulfoisophthalate based on the total dicarboxylic acid and 10% by mass of polyethylene glycol having a weight average molecular weight of 2000 is used as an easily eluting component. , After melting the hardly eluting component and the easily eluting component at 280° C. using an extruder, they were weighed so that the ratio of the hardly eluting component was 85% by mass and the easily eluting component was 15% by mass. Measured with a pump, the poorly eluted components 2 as shown in Fig. 1 are arranged in three locations circumferentially at equal intervals within the fiber, and radially from the center of the fiber so as to divide the hardly eluted components 2. Spinning was performed using a composite spinneret having a fiber cross-sectional structure in which easily eluted component 1 was arranged. Note that FIG. 1 is a schematic diagram showing one aspect of the fiber cross-sectional structure of a three-part split type conjugate short fiber. The spun yarn was cooled while being taken at a speed of 1300 m/min, and then cooled by a cold air blowing cooling device with an air temperature of 20° C., a wind speed of 40 m/min, and a cooling length of 600 mm. After cooling the yarn, 0.1% by mass of process oil was applied, and 20 yarns were combined using a convergence guide via a free roller to obtain an undrawn yarn. Thereafter, while aligning the 20 undrawn yarns, the drawn yarn was stretched at a draw ratio of 2.8 times in hot water at 90°C, and then subjected to tension heat treatment for 5 seconds with a heated roller at 160°C, guided to a crimper, and stretched. Mechanical crimping was applied to the tow at a temperature of 70°C and a pressing pressure of 0.15 MPa, and the resulting crimped tow was dried at 80°C, 0.2% by mass of finishing oil was applied, and a rotary crimper was applied. The fibers were cut to a fiber length of 38 mm using a cutter to obtain splittable composite short fibers with a single fiber fineness of 1.56 dtex (theoretical single fiber fineness of polyester fiber after elution of easily eluted components (but before weight loss): 0.44 dtex). A ring spun yarn having a cotton count of 30 s and a twist coefficient of 3.4 was prepared using 100% by mass of the obtained splittable conjugate short fibers according to a conventional method. After knitting into a 27G tubular knitted fabric using a tubular knitting machine (NCR-ES manufactured by Eiko Sangyo), it was immersed in a sodium hydroxide aqueous solution with a concentration of 70 g/L, and the reduction rate was 200% by mass based on the mass of the tubular knitted fabric. By squeezing with a mangle so that A knitted fabric was produced. The flatness of the fiber cross section after division and weight loss of the above polyester fiber is 4, the single fiber fineness is 0.40 dtex (weight loss rate 9.1% by mass), and the inorganic particles were measured by observation using the SEM described above. The average particle diameter of the fiber was 0.85 μm, and the number of concavities of 0.05 μm ² or more and 0.20 μm ² or less on the fiber surface was 7.2×10 ⁴ /mm ² . In the sensory evaluation of the main tube knitted fabric, the texture was soft and drapey, the surface had a moderately brushed feel (peach touch) and was smooth to the touch, and the fabric had a natural luster similar to silk. It was in good condition.

[Example 2]
A ring spun yarn having a cotton count of 41s and a twist coefficient of 3.6 was prepared by blending 70% by mass of the splittable conjugate staple fiber obtained in Example 1 with 30% by mass of cotton using a conventional method. Thereafter, according to the same procedure as in Example 1, a 27G tubular knitted fabric was knitted, and the easily eluted components were eluted and the hardly eluted components were reduced to produce a cylindrical knitted fabric containing the polyester fiber of the present invention. . The single fiber fineness of the polyester fiber after splitting and weight loss is 0.41 dtex (loss rate: 6.8% by mass), the blending ratio is 65% by mass, and the flatness of the fiber cross section is determined by observation using the SEM described above. 4. The average particle diameter of the inorganic particles was 0.82 μm, and the number of concave portions of 0.05 μm ² or more and 0.20 μm ² or less on the fiber surface was 5.3×10 ⁴ pieces/mm ² . In the sensory evaluation of the main tube knitted fabric, the texture was soft and drapey, and in addition to the smooth feel of the moderately raised surface (peach touch), it also had the smooth touch of cotton, which is a natural fiber. Even though it was a blended product with 200% polyurethane, the fabric had a natural glossy appearance similar to silk.

[Example 3]
Using the ring spun yarn obtained in Example 2, sizing, warping, and weaving were carried out according to conventional methods to produce plain weave Zocchi fabric with a vertical density of 136 yarns/25.4 mm and a horizontal density of 72 yarns/25.4 mm. Created. In the continuous processing process, after the burning process, the dough is immersed in an aqueous solution containing 70 g/L of sodium hydroxide and 2 g/L of hydrogen peroxide, and is mangled so that the squeezing rate is 80% by mass based on the mass of the dough. The polyester of the present invention is obtained by squeezing and steaming in an L-BOX at 100°C for 40 minutes to perform desizing, scouring, elution of easily eluting components, and reducing the amount of hardly eluting components in one step. A woven fabric containing fibers was obtained. The single fiber fineness of the polyester fiber after splitting and weight loss is 0.41 dtex (weight loss rate 6.8% by mass), the blending ratio is 65% by mass, and the flatness of the fiber cross section is 4 according to the observation using the SEM described above. The average particle diameter of the inorganic particles was 0.87 μm, and the number of concave portions of 0.05 μm ² or more and 0.20 μm ² or less on the fiber surface was 5.1×10 ⁴ pieces/mm ² . In the sensory evaluation, the texture was soft and drapey, the surface of the fabric had a peach-like smooth feel even though the surface fuzz was removed by burning, and it was a blended product with cotton. The fabric's appearance maintained a natural luster similar to silk.

[Example 4]
A ring spun yarn having a cotton count of 12s and a twist coefficient of 3.4 was prepared by blending 70% by mass of the splittable composite short fibers obtained in Example 1 with 30% by mass of cotton using a conventional method. Using the ring spun yarn, sizing, warping, and weaving were carried out according to conventional methods to produce a 2/1 twill fabric with a vertical density of 83 threads/25.4 mm and a horizontal density of 48 threads/25.4 mm. In the continuous processing process, after the burning process, the dough is immersed in an aqueous solution containing 70 g/L of sodium hydroxide and 2 g/L of hydrogen peroxide, and is mangled so that the squeezing rate is 100% by mass based on the mass of the dough. The polyester of the present invention is compressed and steamed in an L-BOX at 100°C for 40 minutes to perform desizing, scouring, elution of easily eluting components, and weight reduction of hardly eluting components in one step. A woven fabric containing fibers was obtained. The flatness of the fiber cross section of the polyester fiber after splitting and weight loss was 4, the single fiber fineness was 0.40 dtex (weight loss rate: 9.1% by mass), and the blending rate was 64% by mass, as determined by observation using the SEM described above. The average particle diameter of the inorganic particles was 0.81 μm, and the number of concave portions of 0.05 μm ² or more and 0.20 μm ² or less on the fiber surface was 8.2×10 ⁴ pieces/mm ² . In the sensory evaluation, the texture was soft and drapey, the surface of the fabric had a peach-like smooth feel even though the surface fuzz was removed by burning, and it was a blended product with cotton. The fabric's appearance maintained a natural luster similar to silk.

[Example 5]
Using the hardly eluting component and the easily eluting component described in Example 1, the composition was made to be 80% by mass of the hardly eluting component and 20% by mass of the easily eluting component, and the eluting property as shown in FIG. 2 was obtained. The fiber has a cross-sectional structure in which component 2 is arranged in two circumferentially equally spaced locations within the fiber, and easily eluted component 1 is arranged radially from the center of the fiber so as to separate the hardly eluted component 2. The same processing as in Example 1 was carried out except that a composite die was used and the discharge rate of the spinning process was changed. A split type composite short fiber with a single fiber fineness of 0.77 dtex) was obtained. Note that FIG. 2 is a schematic diagram showing one aspect of the fiber cross-sectional structure of a two-split type split-type conjugate short fiber. A ring-spun yarn with a cotton count of 39s and a twist coefficient of 3.4 was prepared, consisting of 70% by mass of the splittable composite short fibers and 30% by mass of cotton. Thereafter, in the same manner as in Example 1, a tube knitted fabric of 27G was knitted using a tube knitting machine (NCR-ES manufactured by Eiko Sangyo), and then immersed in an aqueous sodium hydroxide solution with a concentration of 70 g/L to determine the mass of the tube knitted fabric. By squeezing with a mangle to a squeezing rate of 200% by mass and steaming at 100°C for 40 minutes, the easily eluted components are eluted and the hardly eluted components are reduced at the same time. A tubular knitted fabric made of the polyester fiber of the present invention was produced. The single fiber fineness of the polyester fiber after splitting and weight loss is 0.71 dtex (weight loss rate 7.8% by mass), the blending ratio is 63% by mass, and the flatness of the fiber cross section is 6 according to the observation using the above-mentioned SEM. The average particle diameter of the inorganic particles was 0.78 μm, and the number of concave portions of 0.05 μm ² or more and 0.20 μm ² or less on the fiber surface was 6.9×10 ⁴ pieces/mm ² . In the sensory evaluation of the main tube knitted fabric, the texture was not as good as that of Example 2, but it was soft to the touch, and in addition to the smooth feel of the moderately raised surface (peach touch), it also had the smooth feel of cotton, which is a natural fiber. It had a nice touch, and even though it was a blend with cotton, the fabric had a natural luster similar to silk.

[Example 6]
Using the ring spun yarn obtained in Example 2, sizing, warping, and weaving were carried out according to conventional methods to produce plain weave Zocchi fabric with a vertical density of 136 yarns/25.4 mm and a horizontal density of 72 yarns/25.4 mm. Created. In the continuous processing process, after the burning process, the dough is immersed in an aqueous solution containing 60 g/L of sodium hydroxide and 2 g/L of hydrogen peroxide, and is mangled so that the squeezing rate is 80% by mass based on the mass of the dough. The polyester of the present invention is obtained by squeezing and steaming in an L-BOX at 100°C for 40 minutes to perform desizing, scouring, elution of easily eluting components, and reducing the amount of hardly eluting components in one step. A woven fabric containing fibers was obtained. The single fiber fineness of the polyester fiber after splitting and weight loss is 0.72 dtex (weight loss rate 6.5% by mass), the blending ratio is 64% by mass, and the flatness of the fiber cross section is determined by observation using the SEM described above. 6. The average particle diameter of the inorganic particles was 0.84 μm, and the number of concave portions of 0.05 μm ² or more and 0.20 μm ² or less on the fiber surface was 5.7×10 ⁴ pieces/mm ² . In the sensory evaluation, the texture was not as good as that of Example 2, but it was soft to the touch, and even though the surface fuzz was removed by burning, the surface of the fabric had a peach-like smooth feel, and it was similar to cotton. Even though it was a blended product, the fabric appearance maintained a natural luster similar to silk.

[Example 7]
Using the hardly eluting component and the easily eluting component described in Example 1, the composition was made to be 80% by mass of the hardly eluting component and 20% by mass of the easily eluting component, and the eluting property as shown in FIG. 2 was obtained. A composite nozzle with a structure in which component 2 is arranged circumferentially at two equally spaced locations within the fiber, and easily eluted component 1 is arranged radially from the center of the fiber so as to divide the hardly eluted component 2. The same processing as in Example 5 was carried out, except that the shape of the discharge hole was rectangular as shown in FIG. 4, and the ratio of the long side to the short side was 2:1. A split type composite staple fiber having a fiber fineness of 1.93 dtex (theoretical single fiber fineness of polyester fiber after elution of easily eluted components (but before weight reduction) of 0.77 dtex) was obtained. Note that FIG. 4 is a schematic diagram showing one aspect of the shape of the discharge hole of the spinneret. A ring spun yarn having a cotton count of 39s and a twist coefficient of 3.4 was prepared by blending 70% by mass of the splittable composite short fibers with 30% by mass of cotton using a conventional method. Thereafter, in the same manner as in Example 6, a plain weave Zocchi fabric with a vertical density of 136 lines/25.4 mm and a horizontal density of 72 lines/25.4 mm was produced, and in the continuous processing process, after the wool burning process, sodium hydroxide was added. Immerse in an aqueous solution containing 50g/L and 2g/L of hydrogen peroxide, squeeze with a mangle so that the squeezing rate is 80% by mass based on the mass of the dough, and steam for 40 minutes at 100°C in an L-BOX. By performing the treatment, desizing, scouring, elution of easily eluted components, and reduction of hardly eluted components were performed in one step, and a fabric containing the polyester fiber of the present invention was obtained. After splitting and weight loss, the single fiber fineness of the polyester fiber was 0.74 dtex (weight loss rate: 3.9% by mass), the blending ratio was 64% by mass, and the flatness of the fiber cross section was found to be 10% by observation using the SEM described above. The average particle diameter of the inorganic particles was 0.78 μm, and the number of concave portions of 0.05 μm ² or more and 0.20 μm ² or less on the fiber surface was 1.1×10 ⁴ pieces/mm ² . In the sensory evaluation of the fabric, the texture was not as good as that of Example 3, but it was soft to the touch, with a moderately brushed surface (peach touch), and a smooth texture of cotton, which is a natural fiber. It had a nice touch, and even though it was a blend with cotton, the fabric had a natural luster similar to silk.

[Example 8]
Using the hardly eluting component and the easily eluting component described in Example 1, the composition was made such that the eluting component was 70% by mass and the easily eluting component was 30% by mass, and the eluting property as shown in FIG. 3 was obtained. A composite having a fiber cross-sectional structure in which component 2 is arranged at four equal intervals circumferentially within the fiber, and easily eluted component 1 is arranged radially from the center of the fiber so as to divide the hardly eluted component 2. The same processing as in Example 5 was carried out, except that a mouthpiece with a rectangular discharge hole shape as shown in FIG. 4 and a ratio of long side to short side of 3:1 was used. A split type composite staple fiber having a fiber fineness of 1.31 dtex (theoretical single fiber fineness of polyester fiber after elution of easily eluted components (but before weight loss) of 0.23 dtex) was obtained. In addition, FIG. 3 is a schematic diagram showing one aspect of the fiber cross-sectional structure of a four-split type split-type conjugate short fiber. A ring spun yarn with a cotton count of 39s and a twist coefficient of 3.4 made of 100% by mass of the splittable composite short fibers was prepared by a conventional method, and subjected to sizing, warping, and weaving to a vertical density of 136 yarns/25.4 mm. A plain weave Zocchi fabric with a width density of 72 lines/25.4 mm was produced. In the continuous processing process, the dough is immersed in an aqueous solution of 90 g/L of sodium hydroxide, squeezed with a mangle so that the squeezing rate is 80% by mass based on the mass of the dough, and steamed at 100°C for 40 minutes in an L-BOX. By performing desizing, scouring, elution of easily eluted components, and reduction of hardly eluted components in one step, a fabric containing the polyester fiber of the present invention was obtained. After splitting and weight loss, the single fiber fineness of the polyester fiber is 0.20 dtex (weight loss rate: 13.0% by mass), the flatness of the cross section of the fiber is 4, and the average particle size of the inorganic particles is determined by observation using the above-mentioned SEM. The diameter was 0.64 μm, and the number of recesses of 0.05 μm ² or more and 0.20 μm ² or less on the fiber surface was 1.1×10 ⁵ /mm ² . In the sensory evaluation, the texture was very soft and drapey, the surface of the fabric had a smooth feel with a peach touch, and although the fabric appearance had some flickering, it maintained a natural luster.

[Example 9]
Using the hardly eluting component and the easily eluting component described in Example 1, the composition was made such that the hardly eluting component was 70% by mass and the easily eluting component was 30% by mass, and the hardly eluting component was on the cross section of the fiber. A sea-island composite nozzle was used, with seven equally spaced locations in the sea-island composite nozzle, and the discharge hole had a rectangular shape as shown in Figure 4, with a long side to short side ratio of 4:1. Other than that, the same processing as in Example 5 was carried out, and sea-island type composite short fibers with a single fiber fineness of 1.31 dtex (theoretical single fiber fineness of polyester fiber after elution of easily eluted components (but before weight loss) of 0.23 dtex) were obtained. I got it. Thereafter, according to the same procedure as in Example 1, a 27G tubular knitted fabric was knitted, and the easily eluted components were eluted and the hardly eluted components were reduced to produce a cylindrical knitted fabric containing the polyester fiber of the present invention. . After splitting and weight loss, the single fiber fineness of the polyester fiber is 0.20 dtex (weight loss rate: 13.0% by mass), the flatness of the cross section of the fiber is 3, and the average particle size of the inorganic particles is determined by observation using the above-mentioned SEM. The diameter was 0.67 μm, and the number of recesses of 0.05 μm ² or more and 0.20 μm ² or less on the fiber surface was 1.3×10 ⁵ /mm ² . In the sensory evaluation, the texture was very soft and drapey, the surface of the fabric had a smooth feel with a peach touch, and although the fabric appearance had some flickering, it maintained a natural luster.

[Example 10]
The cylindrical knitted fabric produced in Example 1 was immersed in an aqueous sodium hydroxide solution with a concentration of 40 g/L, compressed with a mangle to give a reduction rate of 200% by mass based on the mass of the cylindrical knitted fabric, and then compressed at 100°C x 40 A tubular knitted fabric made of the polyester fiber of the present invention was produced by steaming for 1 minute to simultaneously elute easily eluted components and reduce the amount of hardly eluted components. The flatness of the fiber cross section after splitting and weight loss of the polyester fiber is 4, the single fiber fineness is 0.43 dtex (weight loss rate: 2.3% by mass), and the inorganic particles were measured by observation using the SEM described above. The average particle diameter was 0.85 μm, and the number of concave portions of 0.05 μm ² or more and 0.20 μm ² or less on the fiber surface was 7×10 ³ /mm ² . In the sensory evaluation of the main tube knitted fabric, the texture was inferior to the tube knitted fabric of Example 1, but it was soft to the touch, had a moderate raised feel (peach touch) on the surface, and the fabric appearance was silky, although it had some flickering. It was a good product with a natural glossy feel.

[Example 11]
Polymerization and spinning were carried out in the same manner as in Example 1 except that the titanium oxide content in the titanium oxide-containing polyester chips was 0.48% by mass. A split type composite staple fiber with a theoretical single fiber fineness of 0.44 dtex (before weight loss) was obtained. A ring-spun yarn having a cotton count of 41s and a twist coefficient of 3.6 was produced by blending 70% by mass of the obtained splittable conjugate short fibers with 30% by mass of cotton using a conventional method. Using the ring spun yarn, sizing, warping, and weaving were carried out according to conventional methods to produce a plain weave zocchi fabric with a vertical density of 136 threads/25.4 mm and a horizontal density of 72 threads/25.4 mm. In a continuous processing step, the plain weave fabric was sintered and then immersed in an aqueous solution containing 90 g/L of sodium hydroxide and 2 g/L of hydrogen peroxide, and the drawing rate was 80 mass based on the mass of the fabric. %, and then steamed in an L-BOX at 100℃ for 60 minutes to remove desizing, scouring, elute easily eluting components, and reduce the amount of difficultly eluting components in one step. A woven fabric containing the polyester fiber of the present invention was obtained. The single fiber fineness of the polyester fiber after splitting and weight loss is 0.38 dtex (weight loss rate: 13.6% by mass), the blending ratio is 63% by mass, and the flatness of the fiber cross section is 4 according to the observation using the above-mentioned SEM. The average particle diameter of the inorganic particles was 0.96 μm, and the number of concave portions of 0.05 μm ² or more and 0.20 μm ² or less on the fiber surface was 4.4×10 ⁵ pieces/mm ² . In the sensory evaluation, the texture was a little squishy but soft, and despite the removal of surface fluff by burning, the surface of the fabric had a smooth touch with a peach touch, and was slightly dull. It maintained a natural silk-like luster.

[Comparative example 1]
The cylindrical knitted fabric produced in Example 1 was immersed in an aqueous sodium hydroxide solution with a concentration of 10 g/L, compressed with a mangle to give a reduction rate of 80% by mass based on the mass of the cylindrical knitted fabric, and then compressed at 100°C x 40 A tubular knitted fabric made of polyester fibers was produced by steaming for a minute to simultaneously elute easily eluted components and reduce the amount of hardly eluted components. The flatness of the fiber cross section after division and weight loss of the polyester fiber is 4, the single fiber fineness is 0.436 dtex (weight loss rate: 0.9% by mass), and the inorganic particles were measured by observation using the SEM described above. The average particle diameter was 0.78 μm, and the number of concave portions of 0.05 μm ² or more and 0.20 μm ² or less on the fiber surface was 3×10 ³ /mm ² . In the sensory evaluation of the main tube knitted fabric, the texture was soft and smooth to the touch, although it was inferior to the tube knitted fabric of Example 1, but the fabric appearance showed flickering and no natural luster was obtained. .

[Comparative example 2]
Polymerization and spinning were carried out in the same manner as in Example 1, except that the titanium oxide content in the titanium oxide-containing polyester chips was 0.54% by mass. A split type composite staple fiber with a theoretical single fiber fineness of 0.44 dtex (before weight loss) was obtained. A ring-spun yarn having a cotton count of 41s and a twist coefficient of 3.6 was produced by blending 70% by mass of the obtained splittable conjugate short fibers with 30% by mass of cotton using a conventional method. Using the ring spun yarn, sizing, warping, and weaving were carried out according to conventional methods to produce a plain weave zocchi fabric with a vertical density of 136 threads/25.4 mm and a horizontal density of 72 threads/25.4 mm. In the continuous processing process, after the burning process, it is immersed in an aqueous solution containing 90 g/L of sodium hydroxide and 2 g/L of hydrogen peroxide, and is mangled so that the squeezing rate is 80% by mass based on the mass of the dough. By squeezing and steaming at 100°C for 60 minutes in an L-BOX, desizing, scouring, elution of easily eluting components, and reduction of hardly eluting components are performed in one step, resulting in polyester fibers. A fabric containing the following was obtained. The single fiber fineness of the polyester fiber after splitting and weight loss is 0.37 dtex (loss rate: 15.9% by mass), the blending ratio is 63% by mass, and the flatness of the fiber cross section is 4 according to the observation using the above-mentioned SEM. The average particle diameter of the inorganic particles was 0.94 μm, and the number of concave portions of 0.05 μm ² or more and 0.20 μm ² or less on the fiber surface was 5.8×10 ⁵ pieces/mm ² . In the sensory evaluation, the texture was soft and smooth to the touch, but the fabric appearance lacked luster and had a dull texture.

[Comparative example 3]
Polymerization and spinning were carried out in the same manner as in Example 1, except that the titanium oxide content in the titanium oxide-containing polyester chips was 0.08% by mass. A split type composite staple fiber with a theoretical single fiber fineness of 0.44 dtex (before weight loss) was obtained. A ring-spun yarn having a cotton count of 41s and a twist coefficient of 3.6 was produced by blending 70% by mass of the obtained splittable conjugate short fibers with 30% by mass of cotton using a conventional method. Using the ring spun yarn, sizing, warping, and weaving were carried out according to conventional methods to produce a plain weave zocchi fabric with a vertical density of 136 threads/25.4 mm and a horizontal density of 72 threads/25.4 mm. In the continuous processing process, after the burning process, the dough is immersed in an aqueous solution containing 70 g/L of sodium hydroxide and 2 g/L of hydrogen peroxide, and is mangled so that the squeezing rate is 80% by mass based on the mass of the dough. By squeezing and steaming in an L-BOX at 100°C for 40 minutes, the process of desizing, scouring, elution of easily eluting components, and reducing the amount of difficultly eluting components is carried out in one step, resulting in polyester fibers. A fabric containing the following was obtained. The single fiber fineness of the polyester fiber after splitting and weight loss is 0.41 dtex (weight loss rate 6.8% by mass), the blending ratio is 65% by mass, and the flatness of the fiber cross section is 4 according to the observation using the SEM described above. The average particle diameter of the inorganic particles was 0.78 μm, and the number of concave portions of 0.05 μm ² or more and 0.20 μm ² or less on the fiber surface was 1×10 ³ pieces/mm ² . In the sensory evaluation, the texture was soft and smooth to the touch, but the appearance of the fabric did not have a glossy feel and had noticeable glare and flickering.

[Comparative example 4]
The same processing as in Example 8 was carried out except that a nozzle with a round discharge hole shape was used. A splittable composite short fiber with a fineness of 0.23 dtex) was obtained. A ring spun yarn having a cotton count of 39s and a twist coefficient of 3.4 was prepared using 100% by mass of the splittable composite short fibers according to a conventional method. Thereafter, in the same manner as in Example 6, a plain weave Zocchi fabric with a vertical density of 136 lines/25.4 mm and a horizontal density of 72 lines/25.4 mm was produced, and in the continuous processing process, after the wool burning process, sodium hydroxide was added. Immerse in an aqueous solution containing 50g/L and 2g/L of hydrogen peroxide, squeeze with a mangle so that the squeezing rate is 80% by mass based on the mass of the dough, and steam for 40 minutes at 100°C in an L-BOX. By performing the treatment, desizing, scouring, elution of easily eluted components, and reduction of hardly eluted components were performed in one step, and a fabric containing polyester fibers was obtained. After splitting and weight loss, the single fiber fineness of the polyester fiber is 0.20 dtex (weight loss rate: 13.0% by mass), the flatness of the cross section of the fiber is 1, and the average particle size of the inorganic particles is determined by observation using the above-mentioned SEM. The number of recesses with a diameter of 0.64 μm and a size of 0.05 μm ² or more and 0.20 μm ² or less on the fiber surface was 1.2×10 ⁵ /mm ² . In the sensory evaluation of the fabric, it was found that the texture was soft and smooth to the touch due to the fineness of the fabric, but the fabric did not have a glossy feel and had a noticeable flicker in appearance.

[Comparative example 5]
100 parts by mass of dimethyl terephthalic acid, 75 parts by mass of ethylene glycol slurry containing 0.5% by mass of SA-1 manufactured by Sakai Chemical Industry Co., Ltd. (primary particle size 0.15 μm) as titanium oxide, and 0.05 parts by mass of magnesium acetate as a reaction catalyst. 1 part and 0.04 parts by mass of antimony oxide were charged into a transesterification can, and gradually heated from 150°C to 250°C under a nitrogen atmosphere to carry out the transesterification reaction while extracting the methanol produced. 0.05 part by mass was added, and then the temperature was raised to 280° C. while gradually reducing the pressure and polymerization was carried out for 2 hours to obtain titanium oxide-containing polyester (polyethylene terephthalate) chips. The titanium oxide content was 0.27% by mass based on the produced polyester. Using the titanium oxide-containing polyester as the hardly eluting component, a single fiber fineness of 1.56 dtex was obtained using the same method as in Example 1 (theoretical single fiber fineness of the polyester fiber (before weight loss) after elution of the easily eluting component was 0.56 dtex. 44 dtex) split type composite short fibers were obtained. A ring-spun yarn having a cotton count of 41s and a twist coefficient of 3.6 was produced by blending 70% by mass of the obtained splittable conjugate short fibers with 30% by mass of cotton using a conventional method. Using the ring spun yarn, sizing, warping, and weaving were carried out according to conventional methods to produce a plain weave zocchi fabric with a vertical density of 136 threads/25.4 mm and a horizontal density of 72 threads/25.4 mm. In the continuous processing process, after the burning process, the dough is immersed in an aqueous solution containing 70 g/L of sodium hydroxide and 2 g/L of hydrogen peroxide, and is mangled so that the squeezing rate is 80% by mass based on the mass of the dough. By squeezing and steaming in an L-BOX at 100°C for 40 minutes, desizing, scouring, elution of easily eluted components, and reduction of hardly eluted components are performed in one step, and polyester fibers are made into polyester fibers. A fabric containing the following was obtained. The single fiber fineness of the polyester fiber after splitting and weight loss is 0.41 dtex (weight loss rate 6.8% by mass), the blending ratio is 65% by mass, and the flatness of the fiber cross section is 4 according to the observation using the above-mentioned SEM. The average particle diameter of the inorganic particles was 0.30 μm, and the number of concave portions of 0.05 μm ² or more and 0.20 μm ² or less on the fiber surface was 4×10 ³ pieces/mm ² . In the sensory evaluation, the texture was soft and smooth to the touch, but the fabric did not have a glossy appearance and had noticeable flickering.

[Comparative example 6]
Polymerization and spinning were carried out in the same manner as in Comparative Example 5, except that the added inorganic particles were silica with an average particle diameter of 0.9 μm. A split type composite short fiber with a theoretical single fiber fineness of 0.44 dtex) was obtained. A ring-spun yarn having a cotton count of 41s and a twist coefficient of 3.6 was produced by blending 70% by mass of the obtained splittable conjugate short fibers with 30% by mass of cotton using a conventional method. Using the ring spun yarn, sizing, warping, and weaving were carried out according to conventional methods to produce a plain weave zocchi fabric with a vertical density of 136 threads/25.4 mm and a horizontal density of 72 threads/25.4 mm. In the continuous processing process, after the burning process, the dough is immersed in an aqueous solution containing 70 g/L of sodium hydroxide and 2 g/L of hydrogen peroxide, and is mangled so that the squeezing rate is 80% by mass based on the mass of the dough. By squeezing and steaming in an L-BOX at 100°C for 40 minutes, the process of desizing, scouring, elution of easily eluting components, and reducing the amount of difficultly eluting components is carried out in one step, resulting in polyester fibers. A fabric containing the following was obtained. The single fiber fineness of the polyester fiber after splitting and weight loss is 0.40 dtex (weight loss rate: 9.1% by mass), the blending ratio is 63% by mass, and the flatness of the fiber cross section is 4 according to the observation using the above-mentioned SEM. The average particle diameter of the inorganic particles was 1.1 μm, and the number of concave portions of 0.05 μm ² or more and 0.20 μm ² or less on the fiber surface was 2×10 ³ pieces/mm ² . In the sensory evaluation, although the fabric felt soft, it felt bulky to the touch due to the formation of large concavities, and the appearance was dull and lacked gloss.

[Comparative Example 7]
The titanium oxide-containing hard-to-lead polyester chip obtained in Example 1 was used as a single component, and a flat cross-section die with a rectangular discharge hole and a long side to short side ratio of 4:1 was used. Spinning was carried out in the same manner as in Example 1 except that the single fiber was spun to obtain polyester short fibers having a single fiber fineness of 0.90 dtex. A ring spun yarn having a cotton count of 30 s and a twist coefficient of 3.4 was prepared using 100% by mass of the obtained split polyester fiber according to a conventional method. After knitting into a 27G tubular knitted fabric using a tubular knitting machine (NCR-ES manufactured by Eiko Sangyo), it was immersed in a sodium hydroxide aqueous solution with a concentration of 45 g/L, and the reduction rate was 200% by mass based on the mass of the tubular knitted fabric. By squeezing with a mangle and steaming at 100℃ for 40 minutes, the easily eluted components are eluted and the hardly eluted components are reduced at the same time, resulting in a tubular knitted fabric made of polyester fibers. Created. The flatness of the fiber cross section after division and weight loss of the above polyester fiber is 4, the single fiber fineness is 0.85 dtex (weight loss rate 5.6% by mass), and the inorganic particles were measured by observation using the SEM described above. The average particle diameter was 0.64 μm, and the number of concave portions of 0.05 μm ² or more and 0.20 μm ² or less on the fiber surface was 8×10 ³ /mm ² . In the sensory evaluation of the main tube knitted fabric, it was found that the texture was soft to the touch and had a brushed feel, but due to single yarn breakage caused by direct spinning of fine fineness, there was a lot of fuzz on the fabric surface, and the gloss was not good. I couldn't.

[Reference example 1]
A ring spun yarn having a cotton count of 41s and a twist coefficient of 3.6 was prepared by blending 45% by mass of the splittable composite staple fiber obtained in Example 1 with 55% by mass of cotton based on a conventional method. Thereafter, according to the same procedure as in Example 1, a 27G tubular knitted fabric was knitted, and the easily eluted components were eluted and the poorly eluted components were reduced to produce a cylindrical knitted fabric containing polyester fibers. The single fiber fineness of the polyester fiber after splitting and weight loss is 0.40 dtex (weight loss rate: 9.1% by mass), the blending ratio is 39% by mass, and the flatness of the fiber cross section is determined by observation using the SEM described above. 4. The average particle diameter of the inorganic particles was 0.74 μm, and the number of concave portions of 0.05 μm ² or more and 0.20 μm ² or less on the fiber surface was 7.2×10 ⁴ pieces/mm ² . In the sensory evaluation of the main tube knitted fabric, although its characteristics were small compared to other examples, it was superior in softness and feel to the skin than the tube knitted fabric with the same blend ratio using ordinary polyethylene terephthalate, and a certain glossiness was also obtained. , and has good water absorbency compared to cotton, making it a suitable material for blouses and dress shirts.

The fine-grained flat polyester fiber of the present invention provides a silk-like natural luster in addition to the soft texture characteristic of fine-grained fibers, and is therefore suitable for use in general clothing and the like.

1 Easily eluting component 2 Hardly eluting component

Claims (3)

A polyester fiber with a single fiber fineness of 0.20 dtex or more and 0.80 dtex or less, containing 0.10 mass% or more and 0.50 mass% or less of inorganic particles with an average particle diameter of 0.60 μm or more and 1.00 μm or less. , the flatness of the cross section is 3 or more and 10 or less, and the fiber surface has 5 ^{×10 3 or more recesses/mm 2 or more and 5.0×10 5 recesses/mm 2 or more and} 0.20 μm ² or less. Polyester fiber having a diameter of mm ² or less. A woven or knitted fabric containing 40% by mass or more of the polyester fiber according to claim 1. A sea-island type composite fiber having a cross section in which the easily eluted component is a sea and the poorly eluted component is an island, and the easily eluted component is arranged so that the easily eluted component is divided into a plurality of pieces. A conjugate fiber selected from split-type conjugate fibers having a cross section, in which an easily eluting component of the conjugate fiber containing polyester as a hardly eluting component is eluted, and the polyester as the hardly eluting component is 2% by mass or more. The method for producing polyester fiber according to claim 1, characterized in that the weight loss is 15% by mass or less.

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