polyester fiber

Abstract

To provide a polyester fiber desirable in spinnability, causing little cohesion by adhesion among fibers, and capable of curbing effusion of a specified metal component into an environment.SOLUTION: A polyester fiber is a fiber constituted by polyester-based resin, where the polyester-based resin contains a spherical silica particle and the spherical silica particle has a weight average particle diameter of 1.0 μm or less in a particle size distribution measured by a laser diffraction method. It is preferable that the polyester-based resin be copolyester in which a dicarboxylic acid component consists of terephthalic acid and isophthalic acid and a diol component consists of ethylene glycol.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to polyester fibers containing specific silica particles as a fiber filler to replace titanium oxide. [Background technology]

[0002] Polyester fibers have been used for a variety of purposes, such as clothing, industrial materials, etc., because of their excellent mechanical properties and relatively low cost. In addition, heat-bondable core-sheath polyester composite fibers are used for purposes such as maintaining the shape of nonwoven fabrics and cloths, and fusing intersections of mesh fabrics.

[0003] It is known that inorganic particles made of metal components such as titanium oxide are added to polyester resins used for fiber applications as matting agents and smoothing agents (Patent Document 1). However, fibers made of polyester resins containing such inorganic particles contain specific metal components, and depending on the application of such fibers, there is a concern that the metal components may leak into the environment. Furthermore, titanium oxide is classified as a carcinogenic substance in Europe. Therefore, if an attempt is made to produce polyester fibers without adding titanium oxide in order to prevent its release into the environment, the coefficient of friction between the fibers will increase, causing abrasion. Furthermore, during the drawing process or during storage of the product after production, fusion of the fibers may occur at points where the fibers are in close contact with each other.

[0004] On the other hand, Patent Document 2 proposes using silica particles as an alternative to titanium oxide, but silica particles tend to aggregate, which causes frequent breakage of yarns during spinning in the production process, resulting in poor operability. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Patent Publication No. 2014-65989 [Patent Document 2] JP 2002-309444 Summary of the Invention [Problem to be solved by the invention]

[0006] In view of the above problems, an object of the present invention is to provide a polyester fiber that has good spinnability, is less likely to cause fusion due to adhesion between fibers, and can suppress the outflow of specific metal components into the environment. [Means for solving the problem]

[0007] The present invention was arrived at as a result of extensive research aimed at achieving the above object. That is, the present invention provides a fiber made of a polyester resin, the polyester resin containing spherical silica particles, the spherical silica particles having a weight average particle diameter of 1000 to 15000 in a particle size distribution measured by a laser diffraction method. 0.8 μm or less the law of nature, The fibers are no-crimp, short-cut fibers having a fiber length of 2 to 15 mm, and are fibers for use in wet-formed sheets. The gist of the present invention is a polyester fiber characterized by the above. [Effects of the Invention]

[0008] The present invention uses spherical silica particles in polyester fibers instead of titanium oxide, which is commonly used as a fiber filler. The fibers are free of specific metal components, which helps prevent specific hazardous substances from being released into the environment. Furthermore, the spherical shape of the silica particles makes them less likely to aggregate, allowing them to be uniformly distributed in the polyester resin. This reduces friction between fibers, improving operability in fiber production and the production of textile products. Furthermore, it effectively prevents fusion caused by adhesion between fibers during storage, and also provides good handleability when the fibers are made into textile products. [Brief explanation of the drawings]

[0009] [Figure 1] 1 shows an electron microscope photograph of spherical silica particles used in the present invention. [Figure 2] 1 shows an electron microscope photograph of amorphous silica particles. DETAILED DESCRIPTION OF THE INVENTION

[0010] The present invention will be described in detail below.

[0011] The polyester resin constituting the polyester fiber of the present invention contains spherical silica particles, and the spherical silica particles have a weight average particle diameter of 1.0 μm or less in the particle size distribution measured by laser diffraction method.

[0012] In the present invention, it is necessary to use silica particles having a spherical shape. If amorphous silica particles are used, the filler will disperse poorly in the polyester resin and tend to aggregate. The presence of aggregated filler during the spinning and drawing steps in the fiber production process is undesirable because the aggregated filler can become the starting point for breakage at the aggregated portions. In contrast, the silica particles used in the present invention are spherical, so they are less likely to aggregate, disperse well in the polyester resin, and are uniformly dispersed in the resin. Therefore, they have good spinnability and drawability in fiber production. Note that FIG. 1 shows an electron microscope photograph of the spherical silica particles used in the present invention, and FIG. 2 shows an electron microscope photograph of the amorphous silica particles.

[0013] In the present invention, the spherical silica particles have a weight average particle diameter in the particle size distribution measured by a laser diffraction method. 0.8 The weight average particle size of the silica particles is preferably 0.8 μm or less, more preferably 0.6 μm or less. In the case of the silica particles having a weight average particle size of 0.8 μm or less, the silica particles are present without agglomerating with each other, and the operability in the spinning and drawing processes is good, and the polyester system It is easily dispersed uniformly in the resin, and the object of the present invention is achieved.

[0014] In the present invention, the weight-average particle diameter is calculated by the following method. Specifically, polyester fibers containing silica particles are dissolved in a 60 / 40% by mass mixed solvent of phenol and tetrachloroethane to a concentration of 10% by mass, and the resulting solution is diluted with the same solvent to adjust the diffracted / scattered light intensity to a range of 40 to 60%, and then measured using a laser diffraction particle size analyzer (Shimadzu Corporation, model "SALD-7100"). The average value obtained from four measurements is taken as the weight-average particle diameter of the silica particles.

[0015] In the present invention, the specific surface area of ​​the spherical silica particles (measured by the BET method) is preferably as small as possible, and is preferably 50 m 2 / g or less, and 2 / g or less is more preferable, and 10m 2 / g or less is more preferable. A small specific surface area as described above is preferable because it makes it difficult for aggregation to occur in the polyester resin. If the silica particles aggregate, the shape of the silica particles becomes coarse due to aggregation, making it difficult to uniformly disperse the silica particles in the polyester resin, and this leads to the occurrence of broken yarns in the fiber production process, wear on the guides, and other problems that deteriorate operability.

[0016] In the present invention, the polyester-based resin contains the specific spherical silica particles described above, and in order to satisfactorily achieve the desired effects of the present invention, the polyester-based resin preferably contains the spherical silica particles in an amount of 0.05 to 5% by mass, more preferably 0.1 to 2% by mass, and even more preferably 0.2 to 1% by mass. By setting the content within the above range, the desired effects of the present invention can be satisfactorily achieved, spinning and drawing can be performed satisfactorily, and fusion of fibers due to adhesion between fibers during the drawing process and product storage can be prevented.

[0017] The method for adding spherical silica particles to a polyester resin is not particularly limited, and examples thereof include a method in which the spherical silica particles are dispersed in ethylene glycol during polymerization of the polyester resin to be used, thereby uniformly dispersing the particles in the resin, and a method in which the content is controlled by using high-concentration master chips and diluting them with virgin chips, thereby dispersing the particles in the fibers. However, in consideration of uniform dispersion in the fibers when the particles are made into fibers, the former method is more preferred.

[0018] The polyester fiber of the present invention may contain commonly used additives such as antioxidants, delustering agents, colorants, lubricants, and crystal nucleating agents, as long as the effects of the present invention are not impaired.

[0019] The resin constituting the polyester fiber of the present invention is not particularly limited as long as it is a polyester-based resin, and examples thereof include aliphatic polyesters and aromatic polyesters.

[0020] Examples of aliphatic polyesters include poly-α-hydroxy acids such as polylactic acid and polyglycolic acid, poly-β-hydroxyalkanoates such as poly-β-hydroxybutyric acid and poly-(β-hydroxybutyric acid / β-hydroxyvaleric acid), and poly-ω-hydroxyalkanoates such as poly-β-propiolactone and poly-ε-caprolactone.

[0021] Examples of aromatic polyesters include polyesters mainly composed of polyalkylene terephthalate, such as polyethylene terephthalate (PET), polybutylene terephthalate, and polytrimethylene terephthalate. The aliphatic polyester and aromatic polyester may also be copolymerized with the following copolymerization components: Representative examples of the copolymerization components include aromatic dicarboxylic acids such as isophthalic acid, 5-alkaliisophthalic acid, and 3,3'-diphenyldicarboxylic acid, aliphatic dicarboxylic acids such as adipic acid, sebacic acid, and succinic acid, aliphatic and alicyclic diols such as diethylene glycol, 1,4-butanediol, and 1,4-cyclohexanediol, and p-hydroxybenzoic acid.

[0022] In the present invention, the effects of the present invention can be more effectively achieved by using a copolymerized polyester in which the dicarboxylic acid component is composed of terephthalic acid and isophthalic acid and the diol component is composed of ethylene glycol as the polyester resin. Low-melting-point polyester resins copolymerized with isophthalic acid are amorphous and do not exhibit a clear melting point, and begin to soften above their glass transition point. Therefore, if fibers are in close contact with each other during the drawing process or during storage of the manufactured textile product, fusion may occur at the interface between the closely-contacted fibers. In the present invention, because the polyester resin contains specific spherical silica particles, even polyester fibers made of a low-melting-point polyester resin that is amorphous and does not exhibit a clear melting point are less likely to fusion-bond at the contact points, even when the fibers are in close contact with each other, and the coefficient of friction between the fibers is small, making them slippery. The effects of the present invention can be more effectively achieved by using, as the amorphous low-melting polyester resin that does not exhibit a clear melting point, a copolymer polyester in which the dicarboxylic acid component is composed of terephthalic acid and isophthalic acid and the diol component is composed of ethylene glycol, and in which the dicarboxylic acid component contains 18 to 40 mol % of isophthalic acid.

[0023] Among the above-described copolymerized polyesters, when isophthalic acid is used as a copolymerization component of the dicarboxylic acid component, copolymerization amounts of 18 mol% or more are amorphous and do not exhibit a clear melting point. Those copolymerized with 18 mol% isophthalic acid soften and flow in an atmosphere of approximately 200°C, while those copolymerized with 40 mol% isophthalic acid soften and flow in an atmosphere of approximately 100°C. Fibers made from such copolymerized polyesters are also thermally adhesive, eliminating the need for high-temperature heat treatment during thermal bonding, making them suitable for use as binder fibers. In the present invention, despite being a binder fiber, the fibers are less likely to fuse together due to adhesion between fibers during storage, etc., facilitating the storage and management of textile products. Furthermore, if the copolymerization amount of isophthalic acid exceeds 40 mol%, the amount of diethylene glycol produced as a by-product tends to increase, and the glass transition temperature decreases, making adhesion between fibers more likely to occur during drawing in the fiber production process.

[0024] In the present invention, the catalyst used when obtaining the polyester resin by polymerization is not particularly limited, and for example, an antimony catalyst, a titanium catalyst, a germanium catalyst, an organic sulfonic acid catalyst, etc. are preferably used. Among them, organic sulfonic acid compounds are preferably used because they can provide polyester resins with reduced metal content. Examples of organic sulfonic acid compounds include benzenesulfonic acid, m- or p-benzenedisulfonic acid, 1,3,5-benzenetrisulfonic acid, o-, m- or p-sulfobenzoic acid, benzaldehyde-o-sulfonic acid, acetophenone-p-sulfonic acid, acetophenone-3,5-disulfonic acid, o-, m- or p-aminobenzenesulfonic acid, sulfanilic acid, 2-aminotoluene-3-sulfonic acid, phenylhydroxylamine-3-sulfonic acid, phenylhydrazine-3-sulfonic acid, 1- Nitronaphthalene-3-sulfonic acid, thiophenol-4-sulfonic acid, anisole-o-sulfonic acid, 1,5-naphthalenedisulfonic acid, o-, m-, or p-chlorobenzenesulfonic acid, o-, m-, or p-bromobenzenesulfonic acid, o-, m-, or p-nitrobenzenesulfonic acid, nitrobenzene-2,4-disulfonic acid, nitrobenzene-3,5-disulfonic acid, nitrobenzene-2,5-disulfonic acid, 2-nitrotoluene-5-sulfonic acid, 2-nitrotoluene-4-sulfonic acid, 2- Nitrotoluene-6-sulfonic acid, 3-nitrotoluene-5-sulfonic acid, 4-nitrotoluene-2-sulfonic acid, 3-nitro-o-xylene-4-sulfonic acid, 5-nitro-o-xylene-4-sulfonic acid, 2-nitro-m-xylene-4-sulfonic acid, 5-nitro-m-xylene-4-sulfonic acid, 3-nitro-p-xylene-2-sulfonic acid, 5-nitro-p-xylene-2-sulfonic acid, 6-nitro-p-xylene-2-sulfonic acid, 2,4-dinitrobenzenesulfonic acid, 3,5-dinitrobenzene benzenesulfonic acid, o-, m- or p-fluorobenzenesulfonic acid, 4-chloro-3-methylbenzenesulfonic acid, 2-chloro-4-sulfobenzoic acid, 5-sulfosalicylic acid, 4-sulfophthalic acid, 2-sulfobenzoic anhydride, 3,4-dimethyl-2-sulfobenzoic anhydride, 4-methyl-2-sulfobenzoic anhydride, 5-methoxy-2-sulfobenzoic anhydride, 1-sulfonaphthoic anhydride, 8-sulfonaphthoic anhydride, 3,6-disulfophthalic anhydride, 4,6-disulfoisophthalic anhydride, 2,Examples of the sulfonyl sulfonate include 5-disulfoterephthalic anhydride, methanesulfonic acid, ethanesulfonic acid, methionic acid, cyclopentanesulfonic acid, 1,1-ethanedisulfonic acid, 1,2-ethanedisulfonic acid, 1,2-ethanedisulfonic anhydride, 3-propanedisulfonic acid, β-sulfopropionic acid, isethionic acid, dithionic acid, dithionic anhydride, 3-oxy-1-propanesulfonic acid, 2-chloroethanesulfonic acid, phenylmethanesulfonic acid, β-phenylethanesulfonic acid, α-phenylethanesulfonic acid, ammonium chlorosulfonate, methyl benzenesulfonate, ethyl p-toluenesulfonate, ethyl methanesulfonate, dimethyl 5-sulfosalicylate, trimethyl 4-sulfophthalate, and salts thereof. Among these, from the viewpoint of versatility, 2-sulfobenzoic anhydride, o-sulfobenzoic acid, m-sulfobenzoic acid, p-sulfobenzoic acid, 5-sulfosalicylic acid, benzenesulfonic acid, o-aminobenzenesulfonic acid, m-aminobenzenesulfonic acid, p-aminobenzenesulfonic acid, p-toluenesulfonic acid, methyl p-toluenesulfonate, 5-sulfoisophthalic acid, and salts thereof are listed.

[0025] The polyester fiber of the present invention is composed of the polyester-based resin containing the specific spherical silica particles described above. However, it may be a single-phase fiber composed solely of the polyester-based resin containing the specific spherical silica particles, or a fiber in which a portion of the fiber is composed of the polyester-based resin containing the specific spherical silica particles. When the polyester-based resin contains a portion of the fiber, it is preferably a composite fiber in which it is composited with another resin. Examples of composite fibers include a core-sheath type and a side-by-side type. To more effectively achieve the effects of the present invention, the polyester-based resin containing the specific spherical silica particles is preferably disposed on the surface of the fiber. Core-sheath or sea-island type composite fibers are preferred, in which the polyester-based resin containing the specific spherical silica particles is disposed as the sheath or sea component. In this case, it is preferable that the polyester-based resin is a copolymer polyester with a low melting point, as this can further enhance the effects of the present invention. The other resin to be composited is preferably a resin with a higher melting point than the polyester-based resin containing the spherical silica particles. For example, a preferred core-sheath composite fiber is one in which the polyester-based resin containing spherical silica particles is a copolymer polyester in which the dicarboxylic acid component is composed of terephthalic acid and isophthalic acid and the diol component is composed of ethylene glycol, and this copolymer polyester is arranged as the sheath component, while a high-melting point polyester having a melting point higher than that of the copolymer polyester, such as polyethylene terephthalate, is arranged as the core component.

[0026] The cross-sectional shape of the polyester fiber of the present invention is not particularly limited, and may be, for example, a circular cross-sectional shape, a cross-sectional shape, a hexa-lobe cross-sectional shape, or the like. The cross-sectional shape may be controlled by selecting a spinneret to be used depending on the intended use.

[0027] The polyester fiber of the present invention is composed of a polyester-based resin containing specific silica particles in the polyester fiber, and therefore is a specific metal-free fiber, yet exhibits low guide friction during the drawing process, good operability, and a low dynamic friction coefficient against metal. It is more preferable that the polyester fiber have a dynamic friction coefficient of 0.30 or less, as measured by the following method. A dynamic friction coefficient of 0.30 or less effectively reduces guide wear during the spinning and drawing processes. The lower the dynamic friction coefficient, the better. There is no particular limit to the lower limit, but a value of approximately 0.1 is sufficient, for example.

[0028] The dynamic friction coefficient was measured using the following method: A running yarn friction coefficient measuring device (ME-P01, manufactured by Eiko Sangyo Co., Ltd.) was used. A mirror-polished stainless steel round bar with an outer diameter of 16 mm and a length of 100 mm was used as the friction body. The test yarn was brought into contact with the bar at a friction angle of 180°, and the yarn speed was set to 100 m / min, with the tension of the automatic tension controller set to 10 g. The tensions T1 (tension before contact) and T2 (tension after contact) before and after contact between the friction body and the yarn were measured, and the dynamic friction coefficient (μd) was calculated using the following formula: μd={(1 / (friction angle×π / 180)}×ln(T2 / T1)

[0029] The single fiber fineness of the polyester fiber of the present invention is not particularly limited and may be appropriately selected, for example, within the range of about 0.6 to 25 decitex, depending on the intended use of the fiber. For example, when high functionality is important, such as in high-performance filter applications, about 0.6 to 3 decitex is preferably used. On the other hand, when softness to the touch and moderate cushioning are required for cushioning materials, batting for bedding, and batting for clothing, about 2 to 10 decitex is preferably used. Furthermore, when moderate thickness, softness, and cushioning are required, such as solid batting for futons and mattresses, about 4 to 25 decitex is preferably used.

[0030] The polyester fiber of the present invention has the following form: , special It is a short fiber with a certain fiber length. Rusi Short cut fiber R . S Short-cut fibers are materials that are mainly used in papermaking processes, and because they require dispersibility in water, they do not have crimp due to mechanical crimping (no crimp), and the fiber length is is 2 ~15m m be.

[0031] The textile products using the polyester fiber of the present invention include , non Woven fabric (wet papermaking sheet to), Examples of the polyester fiber of the present invention include filling and solid cotton for cushions, etc. Examples of uses of the polyester fiber of the present invention include filters such as gas phase and liquid phase filters, and sanitary material uses such as diapers and face masks.

[0032] As a form of nonwoven fabric , damp Nonwoven fabric (wet-formed sheet) and When the polyester fiber of the present invention is the above-mentioned core-sheath composite fiber, and a low-melting-point copolymer polyester is arranged in the sheath component, the sheath component can function as a thermal adhesive binder component. , damp It can be suitably used as a constituent fiber for wet-formed nonwoven fabrics (wet-formed sheets).

[0033] The basis weight of the nonwoven fabric may be appropriately selected depending on the application and is not particularly limited, but considering flexibility, it is 100 g / cm 2 If the basis weight is too small, the entanglement of the fibers tends to be weak, so it is more preferable that the basis weight is 40 to 100 g / cm 2 The eyes are good.

[0034] The polyester fiber of the present invention may be used alone to make a textile product, or may be mixed or used in combination with other fibers depending on the application or purpose. In addition, when the polyester fiber of the present invention is a core-sheath composite fiber in which a low-melting-point copolymer polyester is used as the sheath component, the sheath component can function as a thermal adhesive binder component, so it is preferable to use it in combination with a fiber composed of a polymer with a high melting point or a natural fiber that does not have a melting point.

[0035] The polyester fiber of the present invention can be obtained by using a polyester resin containing the above-mentioned specific spherical silica particles and appropriately selecting the spinning speed, draw ratio, heat treatment conditions, etc. For example, when obtaining a core-sheath type composite short fiber in which a polyester resin containing spherical silica particles is arranged as a sheath component and a high-melting-point polyester resin is arranged as a core component, a normal composite spinning device is used, melt-spinning is performed at a take-up speed of 900 to 1200 m / min, and the fibers are collected to form a filamentous bundle, which is then drawn at a drawing temperature of 40 to 80°C and a draw ratio of 2 to 5 times, and then cut to a predetermined length to obtain short fibers. . dampness formula non-woven fabric To apply to The fiber is cut to a predetermined length without being crimped. [Example]

[0036] The present invention will be described in detail below based on examples, but the present invention is not limited to these. Measurements and evaluations were carried out by the following methods. The average particle size of silica particles and the fiber dynamic friction coefficient were measured by the methods described above. The fiber dynamic friction coefficient was measured for continuous fibers. (1) Fineness (dtex) Measurement was carried out according to the method of JIS-L-1015-8-5-1-1A. (2) Operability during stretching During the drawing operation, the number of times that yarn breakage occurred during the drawing process (roller drawing) was measured and evaluated according to the following criteria. 〇: Number of thread breakages is less than 0.5 times / ton △: Number of thread breakages is 0.5 to 1.5 times / t ×: Number of thread breakages is 1.5 times / ton or more (3) The incidence of fusion during storage of raw cotton fibers (short-cut fibers) 80 g of fiber to be used as a sample under standard conditions was placed in a polyethylene bag with a zipper ("Unipack C" manufactured by Seisan Nippon Sha, internal dimensions 70 x 100 mm), and the zipper was closed while removing the air from the bag. A 5 mm slit was made with a utility knife near the center of one side of the polyethylene bag containing the fiber, and the entire bag was then gently pressurized to further remove the air from the bag. The slit was sealed with cellophane tape to prevent air from re-entering the bag, forming a state in which the fibers were tightly adhered to each other. 42 bags packed with this fiber (packaged samples) were created, and the density of the bag was measured at an ambient temperature of 30°C using a test strip of 0.036 g / cm. 2 The fibers were removed from the bag between 1 day and 42 days after leaving it, and the degree of fusion between the fibers was evaluated according to the following criteria. In the present invention, it is preferable that the grade is still ⊚ even after 40 days. ◎: 1 liter of water and 10 g of raw cotton were placed in a beaker, stirred at 300 rpm for 10 seconds with a stirrer, and then poured into a large water tank. All fibers were dissociated and no undissociated fibers remained. ○: For packaging samples that had undissociated fibers in the fusion degree evaluation (agitated at 300 rpm for 10 seconds with a mixer, then placed in a large water tank) as described above, 1 liter of water and 10 g of raw cotton were placed in a beaker, and after stirring at 850 rpm for 1 minute with a mixer, the sample was placed in a large water tank. All of the fibers were dissociated, and no undissociated fibers remained. △: For packaging samples that had undissociated fibers in the fusion degree evaluation (agitated at 850 rpm for 1 minute with an agitator and then placed in a large water tank) marked with a circle, 1 liter of water and 10 g of raw cotton were placed in a beaker, and the sample was agitated at 3000 rpm for 1 minute with an agitator and then placed in a large water tank. When the sample was agitated, all of the fibers were dissociated and no undissociated fibers remained. ×: For packaging samples that had undissociated fibers in the fusion degree evaluation (agitated at 850 rpm for 1 minute with an agitator and then placed in a large water tank), 1 liter of water and 10 g of raw cotton were placed in a beaker, and after agitating at 3000 rpm for 1 minute with an agitator, the sample was placed in a large water tank. Not all of the fibers were dissociated, and undissociated fibers were present.

[0037] Example 1 (continuous fiber) The polyester that makes up the fiber is used as a filler during polyester polymerization. Spherical silica particles (Admatechs Co., Ltd., spherical silica particles "Admafine SO-C2" with a specific surface area of ​​4-7 g / m) are used. 2 Polyethylene terephthalate with an intrinsic viscosity of 0.70 and containing 2,4-dimethylamino-3,4-trimethylsilylsilane (SiO 2 ) was used as a polyester resin (the content of spherical silica particles in the polyester resin was 0.5% by mass). This polyester resin was spun using a melt spinning apparatus with a spinneret (diameter 0.20φ) having 36 circular spinning holes at a spinning temperature of 300°C, a take-up speed of 1,400 m / min, and a throughput of 24 g / min to obtain an undrawn yarn. The obtained yarn was drawn at a draw ratio of 3.1 times and a drawing temperature of 90°C to obtain a polyester filament of Example 1 with a single filament fineness of 1.6 dtex. The weight-average particle diameter of the spherical silica particles in the obtained polyester fiber was 0.489 μm, and the fiber dynamic friction coefficient was 0.28. The drawing operability was evaluated as good.

[0038] Comparative Example 1 Polyester continuous fibers of Comparative Example 1 were obtained in the same manner as in Example 1, except that polyethylene terephthalate with an intrinsic viscosity of 0.70, to which amorphous silica particles had been added as a filler during polyester polymerization (the content of amorphous silica particles in the polyester resin was 0.5% by mass), was used as the polyester-based resin. The weight-average particle diameter of the amorphous silica particles in the obtained polyester fibers exceeded 1.0 μm. The fiber dynamic friction coefficient was 0.32, and the drawing operability was evaluated as ×.

[0039] Comparative Example 2 Polyester continuous fibers of Comparative Example 2 were obtained in the same manner as in Example 1, except that polyethylene terephthalate with an intrinsic viscosity of 0.70, to which titanium oxide was added as a filler during polyester polymerization (the content of titanium oxide in the polyester resin was 0.5% by mass), was used as the polyester-based resin. The weight-average particle diameter of titanium oxide in the obtained polyester fibers was 0.425 μm, the fiber dynamic friction coefficient was 0.31, and the drawing operability was good.

[0040] Comparative Example 3 A polyester continuous fiber of Comparative Example 3 was obtained in the same manner as in Example 1, except that polyethylene terephthalate with an intrinsic viscosity of 0.70, to which no filler was added during polyester polymerization, was used as the polyester-based resin. The fiber dynamic friction coefficient of the obtained polyester fiber was 0.35, and the drawing operability was poor.

[0041] Example 2 (Sheath-core type composite short-cut fiber) The sheath component was a copolymer polyester (softening temperature: approximately 130°C) mainly composed of ethylene terephthalate units copolymerized with 33.0 mol% of isophthalic acid (IPA), to which spherical silica particles (manufactured by Admatechs Co., Ltd., spherical silica particles "Admafine SO-C2") were added as a filler during polymerization (the content of spherical silica particles in the copolymer polyester was 0.5% by mass).

[0042] The core component was polyethylene terephthalate with an intrinsic viscosity of 0.72.

[0043] The sheath and core components were combined using a composite melt spinning apparatus with a spinneret (diameter 0.50φ) having 1014 circular spinning holes. The combined fibers were spun at a spinning temperature of 272°C, a take-up speed of 1100 m / min, and a throughput of 550 g / min, yielding an undrawn yarn. The resulting yarns were bundled and drawn at a draw ratio of 3.9 and a drawing temperature of 55°C. A finishing oil was applied and the fiber was cut to a fiber length of 5 mm, yielding a polyester sheath-core composite short-cut fiber of Example 2 with a single fiber fineness of 1.7 dtex. The weight-average particle diameter of the spherical silica particles in the resulting polyester sheath-core composite short-cut fiber was 0.489 μm. The drawing operability was also evaluated as good.

[0044] Comparative Example 4 A polyester sheath-core composite short-cut fiber of Comparative Example 4 was obtained in the same manner as in Example 2, except that a copolymer polyester to which irregular silica particles were added as a filler when polymerizing the copolymer polyester was used as the sheath component (the content of irregular silica particles in the copolymer polyester was 0.5% by mass). The weight-average particle diameter of the irregular silica particles in the obtained polyester sheath-core composite short-cut fiber exceeded 1.0 μm. The drawing operability was also evaluated as poor.

[0045] Comparative Example 5 A polyester sheath-core composite short-cut fiber of Comparative Example 5 was obtained in the same manner as in Example 2, except that a copolymer polyester in which titanium oxide was added as a filler when polymerizing the copolymer polyester was used as the sheath component (the titanium oxide content in the copolymer polyester was 0.5% by mass). The weight average particle diameter of titanium oxide in the obtained polyester sheath-core composite short-cut fiber was 0.425 μm. The drawing operability was also evaluated as good.

[0046] Comparative Example 6 A polyester core-sheath type composite short-cut fiber of Comparative Example 6 was obtained in the same manner as in Example 2, except that a copolymer polyester containing no filler was used as the sheath component in Example 2. The drawing operability was evaluated as poor.

[0047] Table 1 shows the evaluation results of the degree of fusion during storage of raw cotton fibers (short-cut fibers) for Example 2 and Comparative Examples 4-6, which produced short-cut fibers. Example 2 of the present invention quickly dissociated in water even after 42 days, did not fusion during storage, and the fibers were well dispersed in water without deformation. On the other hand, Comparative Examples 4 and 6 fusion occurred after several days. Comparative Example 4 used amorphous silica particles as a filler, and the large specific surface area caused particle aggregation. The coarse particles became the starting point for breakage during the stretching process. Furthermore, the particles were not uniformly distributed throughout the polyester resin, resulting in increased friction with the bar guide in areas where the filler was not present. It is also believed that fusion was more likely to occur in these areas where the filler was not present during storage of the raw cotton.

[0048] In Comparative Example 5, similar to Example 2, no fusion occurred during storage, and the stretching operability was as good as that of the present invention; however, titanium oxide was used as a filler, which is not the objective of the present invention.

[0049] [Table 1]

Claims

1. A fiber made of a polyester-based resin, the polyester-based resin containing spherical silica particles, the spherical silica particles having a weight average particle diameter of 0.8 μm or less in a particle size distribution measured by a laser diffraction method; The polyester fiber is characterized in that the fiber is a no-crimp, short-cut fiber having a fiber length of 2 to 15 mm, and is a fiber for use in a wet-formed sheet.

2. 2. The polyester fiber according to claim 1, wherein the polyester resin is a copolymer polyester in which the dicarboxylic acid component is composed of terephthalic acid and isophthalic acid and the diol component is ethylene glycol.

3. 3. The polyester fiber according to claim 2, wherein the dicarboxylic acid component contains 18 to 40 mol % of isophthalic acid.

4. 3. The polyester fiber according to claim 2, wherein the polyester fiber is a composite fiber obtained by combining a copolyester with a polyester having a higher melting point than the copolyester, and the copolyester is disposed at least on the surface of the fiber.

5. A textile product comprising the polyester fiber according to any one of claims 1 to 4.

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