JP6672641B2 - Extra fine polyester fiber with uneven surface - Google Patents

Description

  The present invention relates to an ultrafine fiber containing inorganic fine particles, which has fine irregularities on the surface of the ultrafine fiber, and has a dry feeling, a sheer-proof property, a mild glossiness when formed into a fabric, and an ultrafine fiber. The present invention relates to an ultrafine polyester fiber which cancels an unpleasant slimy feeling peculiar to a fiber and has a high quality feeling which could not be obtained conventionally.

  Ultrafine polyester fibers having a single fiber diameter of several micrometers have a delicate and soft feeling when made into a fabric, and are therefore widely used as suede-like fabrics and wiping cloths. In particular, as a method of easily producing microfibers, sea-island composite fibers containing a sparingly soluble island component in a sea component composed of a readily soluble polymer, or a sparingly soluble microfiber is a readily soluble polymer. The use of partitioned split-type composite fibers is widely known (see Patent Document 1). These techniques are techniques that, once wound as a composite fiber, remove the easily soluble polymer by immersing the composite fiber or the fabric product in a dissolving agent, thereby making it possible to obtain a hardly soluble microfiber. .

  In recent years, ultrafine polyester fibers having a single fiber diameter of 1 micrometer or less have been proposed in pursuit of more delicate touch and softness. Nanofibers are not only softened by scaling down the fiber diameter, but also have a unique effect of nanosize due to a dramatic increase in the specific surface area and porosity of the single fiber group, which has spurred research and development. I have.

  On the other hand, there is disclosed a technique for improving texture and color by imparting fine irregularities to the fiber surface. For example, Patent Literature 2 discloses a method for producing a synthetic fiber having a fine and complex uneven shape by adding fine particles having a diameter of 80 mm or less to a synthetic fiber-forming polymer and performing elution treatment on the fiber surface after forming the fiber. It has been disclosed. It is said that this improves the waxy feeling and specular gloss peculiar to synthetic fibers, and provides a deeper color.

  Patent Document 3 discloses a polyester fiber obtained by mixing a polyester containing inorganic fine particles with a polyester having a higher dissolution rate in a hot alkali aqueous solution than the polyester. By forming microvoids and streaky grooves, polyester fibers that have a unique texture such as dryness, kissiness, sharpness, warmth, and pastel glossiness in addition to opacity when woven and knitted The technology provided is disclosed.

  Patent Document 4 discloses that a fiber containing a specific water-soluble compound is treated to form a fiber having specific fine pores on the fiber surface, so that the dye exhaustion rate in dyeing is high and the color development of a dark color is excellent. A technique relating to polyester fibers excellent in electrostatic property and process passability is disclosed.

  However, all of the above techniques are techniques applied to fibers having a fiber diameter of 10 μm or more and a normal thickness, and have a suede-like fabric or wiping cloth function with ultra-fine fibers, delicate touch, soft feeling, and drape property. On the other hand, there has not been obtained a fiber which imparts a dry feeling, anti-penetration property, mild glossiness, and cancels out the unpleasant slimy feeling peculiar to ultrafine fibers, and development has been awaited.

JP 2005-163234 A JP-A-54-120728 JP-A-11-222725 JP 2003-166123 A

  The object of the present invention is to solve the above-mentioned problems, and to maintain a delicate touch, soft feeling, and drape property while being an ultra-fine fiber, to impart a dry feeling, a sheer-proof property, a mild glossiness, and an ultra-fine fiber. An object of the present invention is to provide an ultrafine polyester fiber capable of canceling an unpleasant slimy feeling peculiar to the fiber and imparting high added value of the ultrafine fiber.

The above problem can be solved by the following configuration.
(1) Ultrafine fibers having an average particle size of 0.10 to 0.50 μm and containing inorganic fine particles selected from titanium oxide, zirconia, and alumina, and having a fiber diameter of 590 to 6000 nm, and having a fine surface An ultra-fine polyester fiber having fine irregularities and satisfying the following requirements A and B:
A. The number of small projections 1-15 pieces / 40 [mu] m ²
B. The size of fine unevenness is characterized in that it contains 1.0 to 8.0 wt% of the aspect ratio of 10 or less (2) No machine microparticles (1) ultrafine polyester fiber as claimed.

  According to the present invention, suede-like fabric of ultrafine fiber and wiping cloth function, delicate touch and softness, maintain drapability, dryness, anti-shedding property, mild glossiness, and even extrafine fiber It is possible to provide an ultrafine polyester fiber capable of imparting a high added value, such as being able to cancel the unpleasant slimy feeling of the above.

FIGS. 1A and 1B show an example of a cross section of a single yarn of the sea-island composite fiber of the present invention.

Hereinafter, the ultrafine polyester fiber of the present invention will be described in detail.
That is, in the present invention, the surface of the ultrafine polyester fiber has fine irregularities, and the number of the fine irregularities needs to be 1 to 19/40 μm ² .

When the number of fine irregularities on the surface is 1/40 μm ² or more, the fiber surface is not flat, and it is not a slimy feeling or an unfavorable metallic feeling, but a dry feeling, a sharp feeling, a high touch feeling, a smooth and comfortable texture. Is preferable.

When the number of the fine irregularities is 19/40 μm ² or less, it is preferable that physical properties such as the elongation characteristic of the ultrafine fiber are not reduced. More preferably, it is 2 to 15 pieces / 40 μm ² , and particularly preferably 5 to 10 pieces / 40 μm ² .

  The fine irregularities refer to fine holes and fine protrusions formed on the fiber surface. The fine holes and projections are depressions and projections observed on the fiber surface with an electronic scanning microscope, and those having a size of 0.1 μm or more are called. Fine pores are pores in which inorganic fine particles fall off from the fiber surface when the sea component polymer is dissolved and removed, and fine projections indicate a state in which inorganic fine particles do not fall off and remain on the fiber surface.

  The fine irregularities have a favorable effect on the texture, and are completely different from the conventional materials, exhibiting a dry feeling, a sharp feeling, a high touch feeling, that is, a smooth feel. In addition, while maintaining the delicate touch, softness and drape characteristic of microfibers, it is possible to create a new material by overcoming the slimy feeling that is unique to microfibers. Can be obtained.

The size of the fine irregularities on the fiber surface of the present invention needs to have an aspect ratio of 10 or less. The aspect ratio referred to here is defined as follows.
In the shape of a concave or groove on the fiber surface, the direction parallel to the fiber axis direction is length (L),
A direction perpendicular to the width is defined as a width (W), and a ratio of the length to the width of the shape (C) is defined as an aspect ratio (C = L / W).
The aspect ratio of 10 or less means that fine pores on the fiber surface, that is, fine irregularities generated during dissolution and removal of the sea component polymer, are not streaky grooves along the fiber axis direction, but pores from which inorganic fine particles have escaped. It means that If the fine irregularities have streaky grooves along the fiber axis direction, that is, if the aspect ratio exceeds 10, a slimy feeling is exhibited, which is not preferable. This is because the streaky grooves increase the surface area when touching the skin, act as if the fiber diameter is small, and behave like ultra-fine fibers, so that a slimy feeling is exhibited. The preferred range of the aspect ratio is 8 or less, more preferably 6 or less.

The fiber diameter of the ultrafine polyester fiber of the present invention is preferably 50 to 6000 nm.
By having a fiber diameter of 50 nm or more, it is possible to contain inorganic fine particles while being a sufficiently fine fiber, and to have a sheer-proof property, a mild glossiness, and to express fine irregularities by alkali weight reduction processing, It is preferable because the strength and elongation can be reduced while having a good texture.
Further, when the fiber diameter is 6000 nm or less, in addition to the delicate touch and soft touch, which are the characteristics of the ultrafine fiber, the suede-like fabric utilizing the drape property, the wiping performance due to the increase in the specific surface area and the porosity, and the dry feeling. This is preferable since it can impart a low gloss, show-through resistance, and express a mild glossiness.

Further, the ultrafine polyester fiber (fiber diameter 50 to 6000 nm) of the present invention is characterized by having a large specific surface area and a small number of fine irregularities per unit area as compared with a fiber having a normal thickness. About 1/5 of the fibers (fiber diameter of 10 to 20 μm) are preferable because good texture can be exhibited and a decrease in yarn physical properties can be suppressed. This is one of the features of the present invention, in which a synergistic effect is produced by forming fine irregularities in the ultrafine fibers with a controlled number per unit area.
In addition, the fiber diameter of the ultrafine polyester fiber of the present invention is more preferably 100 to 5000 nm, particularly preferably 200 to 4000 nm.

The ultrafine polyester fiber of the present invention preferably contains inorganic fine particles in an amount of 1.0 to 8.0 wt%. When the content of the inorganic fine particles is 1.0% by weight or more, the antireflection property is exhibited, a mild glossy feeling is obtained, and the number of fine irregularities is 1/40 μm ² or more which can be felt as a good texture, which is preferable. . Further, when the content of the inorganic fine particles is 8.0 wt% or less, it is preferable because a decrease in the spinning property can be avoided and the physical properties of the fiber are within a range in which there is no practical problem. It is more preferably at least 3.0 wt% , particularly preferably 5.0 to 7.0 wt% .
As the inorganic fine particles, for example, titanium oxide , zirconia, or alumina can be used. Among them, titanium oxide is excellent in opacity, and is more preferable in terms of ease of handling, price, various functions against sunlight, and the like. For example, titanium oxide absorbs and blocks ultraviolet rays that are harmful to the skin and efficiently reflects the visible and near-infrared regions of sunlight that feels hot. Can be particularly preferably used because it has an effect of suppressing the temperature of the above.
The inorganic fine particles of the present invention preferably have an average particle diameter in the range of 0.10 to 0.50 μm.

  The cross-sectional shape of the ultrafine polyester fiber of the present invention can be applied without any particular limitation, such as a round cross section, an irregular cross section, and a flat cross section.

  The ultrafine polyester fiber of the present invention can be obtained by micronizing the sea-island composite fiber.

  The fine irregularities on the surface of the ultrafine polyester fiber contain inorganic fine particles in the island component polymer, and the inorganic fine particles fall off from the fiber surface and the vicinity of the surface when the sea component polymer is dissolved and removed, thereby generating fine irregularities.

Hereinafter, the sea-island type conjugate fiber of the present invention will be described in detail.
In the sea-island type composite fiber of the present invention, it is necessary that the easily soluble polyester is a sea component and the hardly soluble polyester is an island component. The polymers forming the sea or islands are incompatible with each other, and polyester which is a fiber-forming thermoplastic polymer is used. When the island component is made of polyester, a soft texture without slimy feeling can be obtained when the ultrafine fibers are obtained by dissolving and removing the sea component polymer. In addition, since the sea component is made of polyester, it is excellent in the spinning property when spinning sea-island composite fibers and in the process passability when forming a woven or knitted fabric using sea-island composite yarns. Examples of the polyester used for the island component and / or the sea component include polyethylene terephthalate, polybutylene terephthalate, and polypropylene terephthalate, and those obtained by copolymerizing a dicarboxylic acid component, a diol component, or an oxycarboxylic acid component, or polyesters thereof. Blended ones can be mentioned. Further, aliphatic polyesters such as polylactic acid, polybutylene succinate, and polyε-caprolactam known as biodegradable polyesters may be used. If necessary, inorganic fine particles, organic compounds and carbon black can be added to these polyesters as matting agents, flame retardants, lubricants, antioxidants, coloring pigments and the like.

  Examples of combinations of polymers of sea-island composite fibers used in the present invention are listed below. When the sea component polymer dissolving agent is an aqueous alkali solution, a copolymer polyester resin or an aliphatic polyester resin is combined with the sea component polymer, and a homopolyester resin, a polyester resin made of an aromatic dicarboxylic acid, or the like is combined with the island component polymer.

  The content of the inorganic fine particles contained in the island component needs to be 1.0 to 10.0 wt%. By setting the content in this range, the content of the inorganic fine particles in the ultrafine fibers after dissolving and removing the sea component polymer can be set to 1.0 to 10.0 wt%, which is preferable.

  The content of the inorganic fine particles contained in the sea component is preferably from 0.1 to 0.8 wt%. 0.1% by weight or more reduces the friction between each guide or roller and the fiber surface when the sea-island composite fiber is produced and when the woven or knitted fabric is produced using the sea-island composite fiber. The spinning property and the processability are stable, and the quality of fluff and the like is improved. By adjusting the content to 0.8 wt% or less, the wear of each guide is suppressed during the process of producing the sea-island composite fiber and the process of producing a woven or knitted fabric using the sea-island composite fiber, and the sea-island composite is produced over time. Maintains the physical properties of the fiber and the quality of fluff, etc., and stabilizes the spinning properties and processability.

  The island component of each single thread must be completely covered by the sea component. The island component contains 1.0 to 10.0% by weight of inorganic fine particles. When the island component is exposed on the fiber surface, the island-in-sea type composite fiber is plied or woven using the island-in-sea type composite fiber. The wear of each guide progresses during the process of producing a knitted fabric, and the physical properties of the sea-island composite fiber and the quality of fluff and the like deteriorate, the spinning properties, and the process passability become unstable over time. By completely covering the island component with the sea component, the spinning property and the process passability are stabilized for a long time.

  Further, the island component of each single yarn needs to be completely separated into the sea component. As a result, uniform ultrafine fibers can be obtained after the dissolution and removal of the sea component polymer, and as a result, a woven or knitted fabric having a good texture can be obtained.

  It is necessary that the fineness of the sea-island composite fiber is 12 to 300 dtex, the number of single yarns is 5 to 400, and the number of islands per single yarn is 4 to 1200. By setting the fineness of the sea-island type composite fiber, the number of single yarns, and the number of islands per single yarn within this range, it is possible to obtain the ultrafine fibers having a preferable fiber diameter of 50 nm to 6000 nm of the present invention in a state in which the spinning property and process passability are stable. And a woven or knitted fabric having a good texture and appearance can be obtained.

  When the fineness of the sea-island type composite fiber is less than 12 dtex, the spinning property and the processability deteriorate. When the fineness exceeds 300 dtex, the fineness of the ultrafine fibers after dissolving and removing the sea component polymer increases, and the texture of the woven or knitted fabric decreases. If the number of single yarns and / or the number of islands per single yarn is increased in order to obtain an ultrafine fiber having a fiber diameter of 50 nm to 6000 nm, the spinning property and the process passability deteriorate.

  If the number of single yarns is less than 5, the diameter of the ultrafine fibers after dissolving and removing the sea component polymer becomes large, and the texture of the woven or knitted fabric decreases. When the number of islands is increased to obtain ultrafine fibers having a fiber diameter of 50 to 6000 nm, the area variation of the island components increases, and ultrafine fibers having a uniform fiber diameter cannot be obtained. Absent. When the number of single yarns exceeds 400, the fiber diameter of the ultrafine fibers becomes non-uniform due to the deterioration of the yarn-making properties and process passability due to the increase in the fluff of the sea-island composite fibers, and the deterioration of U% unevenness.

  If the number of islands is less than 4, the diameter of the ultrafine fibers after dissolving and removing the sea component polymer becomes large, and the texture of the woven or knitted fabric decreases. When the number of single yarns is increased in order to obtain ultrafine fibers having a fiber diameter of 50 to 6000 nm, the fiber diameter of the ultrafine fibers tends to be non-uniform due to the deterioration of the yarn forming property, the processability, and the U% unevenness due to the increase in the fluff of the composite fibers. There is. If the number of islands exceeds 1200, the variation in the area of the island components becomes large, ultrafine fibers having a uniform fiber diameter cannot be obtained, and a fine texture cannot be obtained when a woven or knitted fabric is used.

  The strength of the sea-island composite fiber of the present invention is preferably 2.5 to 5.5 cN / dtex. When the strength is 2.5 cN / dtex or more, excellent spinning properties and process passability are obtained. In addition, the strength of the ultrafine fibers after dissolving and removing the sea component polymer can be 1.5 cN / dtex or more, and the fibers can be suitably used for sports clothing, which has a relatively severe use environment. By setting the strength to 5.5 cN / dtex or less, stable spinning properties can be obtained, and a sea-island composite fiber having a small area variation of island components can be obtained. In order to exceed a strength of 5.5 cN / dtex, it is necessary to use a polymer having a high intrinsic viscosity or to set a high draw ratio. As a result, the yarn formability and fluff quality may be deteriorated, and the sea-island component may be peeled off. More preferably, it is 3.0 to 5.0 cN / dtex.

  The elongation is preferably 20 to 50%. By setting the elongation to 50% or less, excellent dimensional stability is obtained when a woven or knitted fabric is produced. If the elongation is less than 20%, the spinnability and fluff quality may be deteriorated, and the sea component may be peeled off. More preferably, it is 25 to 45%.

  U% (N), which is an index of thickness unevenness in the fiber longitudinal direction, is preferably 2.0% or less. By setting the content to 2.0% or less, the variation in the area of the island component is reduced, ultrafine fibers having a uniform fiber diameter are obtained after the dissolution treatment of the sea component polymer, and a woven or knitted fabric having a good texture is obtained. More preferably, it is at most 1.8%.

  The area variation of the island component in each single yarn of the sea-island composite fiber of the present invention is preferably 1 to 20%. By adjusting the content to 20% or less, ultrafine fibers having a uniform fiber diameter can be obtained after dissolving and removing the sea component polymer. 1% or more is a practical range. More preferably, it is 1 to 16%.

Next, a preferred method for producing the sea-island composite fiber and / or the ultrafine polyester fiber of the present invention will be described more specifically with reference to an example.
First, a polyester containing 70.0 mol% or more of polyethylene terephthalate obtained by polymerizing terephthalic acid and ethylene glycol is used as an island component polymer that is hardly soluble in the dissolving agent used in the present invention. Polyester containing 1.0 to 10.0 wt% of inorganic fine particles can be preferably used.

The number of fine irregularities of the present invention can be adjusted by the content of the inorganic fine particles. When the content of the inorganic fine particles is 1.0% by weight or more, the transparent property is exhibited, a mild gloss is obtained, and the number of fine irregularities can be felt as a good texture when the sea component polymer is dissolved and removed. Pcs / 40 μm ² or more, which is preferable. Further, when the content of the inorganic fine particles is 10.0% by weight or less, it is preferable because a decrease in the spinning property can be avoided and the physical properties of the fiber are within a range in which there is no practical problem. More preferably, it is 3.0 to 8.0 wt%, particularly preferably 5.0 to 7.0 wt%.

  Increasing the addition of the particles increases the number of fine irregularities, and decreasing the amount of addition reduces the number of fine irregularities. Further, although a slight adjustment is possible at the time of dissolving and removing the sea component polymer, it is preferable to adjust the fiber so as to have a practical hand with a good texture and a good fiber elongation in consideration of fiber properties.

  As the inorganic fine particles, for example, titanium oxide, silica, zirconia, or alumina can also be used. Among them, titanium oxide is excellent in opacity, and is more preferable in terms of ease of handling, price, various functions against sunlight, and the like. For example, titanium oxide absorbs and blocks ultraviolet rays that are harmful to the skin, and efficiently reflects the visible and near-infrared regions of sunlight that feels hot. Since it has the effect of suppressing the temperature, it can be particularly preferably used.

  The inorganic fine particles of the present invention preferably have an average particle diameter in the range of 0.01 to 0.50 μm. When the inorganic fine particles have such an average particle size, the size of the fine unevenness is preferably 10 or less when the sea component polymer is dissolved and removed, which is preferable.

The easily soluble polyester used for the sea component of the present invention preferably has a dissolution rate with respect to a dissolving agent that is at least 5 times greater than that of a normal homopolyester.
The easily soluble polyester is preferably a copolymerized polyester obtained by copolymerizing 5-sodium sulfoisophthalic acid from the viewpoint of easy handling and spinnability. Further, the preferable copolymerization ratio is preferably 1.5 to 10.0 mol% from the viewpoint of stabilization of the yarn physical properties and the spinning properties.

As the sea component polyester, those containing 1.0 to 10.0 wt% of inorganic fine particles can be preferably used.
As the inorganic fine particles, for example, titanium oxide, silica, zirconia, or alumina can also be used. Among them, titanium oxide is excellent in opacity, and is more preferable in terms of ease of handling, price, various functions against sunlight, and the like.
The inorganic fine particles having an average particle diameter in the range of 0.01 to 0.50 μm can be preferably used. When the average particle size is less than 0.01 μm, the particle activity increases, the viscosity increases due to the aggregation of the particles, and the yarn-making properties of the sea-island composite fiber deteriorate. If the thickness exceeds 0.50 μm, clogging of the filter in the pack and spinnability deteriorate when spinning the sea-island composite fiber.

  As described above, the preferred combination of the sea component polymer and the island component polymer of the present invention comprises a sea component of a polymer that is easily soluble in a dissolving agent and an island component of a sparingly soluble polymer. Both polymers are incompatible with each other, and it is important that the yarn is formed in the largest possible combination as long as there is a difference in dissolution rate when dissolving and removing the sea component polymer. As the range of the dissolution rate, an island component polymer in which the dissolution rate of the sea component polymer is at least 5 times the dissolution rate of the island component polymer or that is completely insoluble in the dissolving agent is selected. By making the dissolution rate difference 5 times or more, the dissolution and removal of the sea component polymer is smoothly performed, and the contact time difference between the island component solubilizer at the surface / core portion of the single fiber of the sea-island composite fiber is reduced. An ultrafine single yarn group having a small fiber diameter variation can be obtained. A more preferable range of the dissolution rate difference is 20 times or more.

Specific examples of the spinning mode are described below. A polymer having a dissolution rate difference of 5 times or more of the sea-island component is selected as the sea component polymer and weighed so that the weight ratio of the sea component polymer in the ultrafine polyester fiber is 5 to 45 wt%.
The island component polymer that is hardly soluble in the dissolving agent is measured and melted and discharged so that the weight ratio is 55 to 95 wt%.

  The spinning temperature is set at a temperature +20 to + 50 ° C. higher than the melting point of the polymer. By setting the temperature higher than the melting point of the polymer by at least + 20 ° C., it is possible to prevent the polymer from solidifying and clogging in the spinning machine piping. This is preferable because deterioration can be suppressed.

  As a base used for the sea-island type conjugate fiber and the ultrafine polyester fiber of the present invention, an existing sea-island type ultrafine base can be preferably used. That is, a conventionally known pipe-type sea-island composite base can be used. Furthermore, a sea-island type composite fiber having a small variation in the island component area is obtained by using a composite die in which three types of members, namely, a measuring plate, a distribution plate, and a discharge plate, described in JP-A-2011-174215 are laminated. Is preferred.

The sea-island type conjugate fiber and the ultrafine polyester fiber of the present invention can be obtained by a two-step method in which the discharged polymer is once wound as an undrawn yarn and then drawn, a direct spin drawing method in which the spinning and drawing steps are continuously performed, and a high-speed drawing method. It can be manufactured in any process such as a spinning method. In addition, since the range of the spinning speed in the high-speed spinning method is not particularly defined, it may be a step of drawing after winding as a semi-drawn yarn. Further, if necessary, yarn processing such as false twisting can be performed.
In the case of the two-step method, any known drawing method can be used in addition to hot roll-hot roll drawing and drawing using a hot pin, and the obtained undrawn yarn is once wound as an undrawn yarn.

In the case of the direct spinning drawing method, drawing is performed via a hot roll between hot rolls without being wound once. In the case of the high-speed spinning method, the winding speed is appropriately adjusted and the drawn yarn is wound. The spinning draft represented by the following formula for the sea-island composite fiber and the ultrafine polyester fiber of the present invention is preferably set to 50 to 300. The spinning draft is a value calculated below.
Spinning draft = Vs / V0
Vs: spinning speed (m / min)
V0: Discharge linear velocity (m / min)
By setting the spinning draft to 50 or more, the polymer flow discharged from the spinneret hole is prevented from staying directly below the spinneret for a long time, and the spinneret can be prevented from being stained. Further, by setting the spinning draft to 250 or less, it is possible to suppress yarn breakage due to excessive spinning tension, and it is possible to stably produce ultrafine polyester fibers, which is preferable. More preferably, it is 80 to 250.

  The spinning stress of the sea-island composite fiber and the ultrafine polyester fiber of the present invention is preferably 0.02 to 0.15 cN / dtex. By setting the spinning stress to 0.02 cN / dtex or more, there is no yarn interference between the single yarns due to yarn sway during spinning, and there is no reverse winding on the take-up roll as the first roll, so that stable running is possible. Become. Further, it is preferable that the spinning stress be 0.15 cN / dtex or less, since the ultrafine polyester fiber can be stably produced. A more preferable range of the spinning stress is 0.07 to 0.10 cN / dtex.

  In the operation and quality stabilization of the sea-island composite fiber and ultrafine polyester fiber of the present invention, it is preferable to appropriately control the cooling and solidification of the discharged polymer. If the amount of the discharged polymer is suppressed due to the fineness, fineness of the polymer and cooling and solidification will be started immediately after the discharge. I can't get it. In addition, since the accompanying airflow due to the solidified fibers increases and the spinning stress increases, a method for improving the spinnability is required.

In order to solve these problems, it is necessary to set the cooling start point at 20 to 120 mm from the base surface. It is preferable that the cooling start point is 20 mm or more, because it is possible to suppress a decrease in the surface temperature of the die due to the cooling air, and to avoid various problems such as low-temperature yarn, clogging of the die hole, complex abnormality, and uneven discharge. In addition, it is preferable that the cooling start point be 120 mm or less, because a high-quality extra-fine polyester fiber with few thread spots in the longitudinal direction can be obtained. A more preferable range of the cooling start point is 25 to 100 mm.
Further, in order to suppress a decrease in the temperature of the die surface due to the cooling air, the temperature of the cooling air may be controlled or a heater may be installed around the die as necessary.

  It is preferable that the distance from the base discharge surface to the refueling position be 1300 mm or less. By setting the distance from the nozzle discharge surface to the lubrication position to 1300 mm or less, it is possible to suppress the yarn swaying width due to the cooling wind, improve the yarn unevenness in the fiber longitudinal direction, and suppress the accompanying air flow until the yarn converges. Therefore, the spinning tension can be reduced, and stable spinning properties with less fluff and yarn breakage can be easily obtained. A more preferable range of the oil supply position in the spinning process of the sea-island composite fiber and the ultrafine polyester fiber is 1200 mm or less.

  The ultrafine polyester fiber of the present invention can be obtained by dissolving and removing the sea component polymer of the sea-island composite fiber of the present invention. As a method for removing the sea component polymer, when the sea component polymer is alkali-soluble, alkali reduction treatment generally performed with polyester fibers is preferable. An example is shown below. As the alkali aqueous solution, an aqueous solution of 1 to 5% by weight of sodium hydroxide can be preferably used, and the alkali reduction treatment temperature is preferably in the range of normal temperature (25 ° C) to 98 ° C. In addition, the treatment time can be appropriately adjusted according to the weight ratio of the sea component polymer, but is preferably about 5 to 60 minutes. By this weight loss treatment, fine irregularities can be formed on the fiber surface, and an excessive weight loss treatment can be performed within a maximum of about 5 wt% for the formation of the fine irregularities.

  The sea-island type composite fiber of the present invention is subjected to ordinary alkali weight reduction treatment, and the weight loss treatment is most effective after weaving and weaving. Thereby, in addition to the delicate touch and soft touch, which are the characteristics of the ultrafine fibers aimed at by the present invention, the suede-like fabric utilizing the drape property, the wiping performance by increasing the specific surface area and the porosity, and imparting a dry feeling It is possible to produce a novel woven or knitted fabric using ultra-fine polyester fiber having a high quality that cannot be obtained by the prior art, which can exhibit a sheer-proof property and a mild glossiness.

  Hereinafter, the present invention will be described in detail with reference to examples. In addition, the measuring method in an Example is as follows.

(1) Intrinsic viscosity (IV)
Ηr in the definition formula is obtained by dissolving 0.8 g of a sample polymer in 10 mL of O-chlorophenol (OCP) having a purity of 98% or more and using a Ostwald viscometer at a temperature of 25 ° C to obtain a relative viscosity ηr according to the following equation. , Intrinsic viscosity (IV) was calculated.
ηr = η / η0 = (t × d) / (t0 × d0)
Intrinsic viscosity (IV) = 0.0242ηr + 0.2634
[Η: viscosity of polymer solution, η0: viscosity of OCP, t: fall time of solution (sec), d: density of solution (g / cm ³ ), t0: fall time of OCP (sec), d0: OCP Density (g / cm ³ )].

(2) Fineness of composite fiber Using a scale measuring machine with a frame circumference of 1.0 m, 100 sets of scabs were produced, and the fineness was measured according to the following formula.
Fineness (dtex) = Kase weight (g) for 100 times × 100.

(3) Exposure of island components in each single yarn of the composite fiber and separation of island components by sea components Observation was made with a scanning electron microscope (SEM: S-3000N manufactured by Hitachi, Ltd.). Observe all single yarns of the obtained composite fiber and check whether the island component is completely covered by the sea component, that is, whether the island component is exposed to the fiber surface and whether the island component is completely separated by the sea component confirmed.

(4) Area variation of island component of composite fiber Observed with a scanning electron microscope (SEM: S-3000N manufactured by Hitachi, Ltd.). Five single yarns are randomly selected from all single yarns, and four islands are randomly selected from each single yarn. A total of 20 islands were observed. The magnification was adjusted as appropriate so that one single yarn was included in the image, and photographed. The area of the obtained image was measured using image processing software (WINROOF), and the average value and standard deviation of 20 islands were obtained. From these results, the area variation of the island component was calculated based on the following equation.
Area variation of island component (CV%) = (standard deviation / average value) × 100.

(5) Average fiber diameter of island component single yarn group A single yarn group of ultrafine fibers composed of island components after dissolving and removing sea components was observed with a scanning electron microscope (SEM: S-3000N manufactured by Hitachi, Ltd.). Fifty fibers were randomly selected from the ultrafine fiber single yarn group, and the average fiber diameter was calculated from the measured values.

(6) Yarn production stability Yarn production was performed for each example, and the yarn production stability of the sea-island composite fiber was evaluated in four steps based on the number of yarn breaks per 24 hours. △ to △ were acceptable, and × was unacceptable.
Excellent ◎: 0 times Good ○: Less than 1 or 2 times Possible △: Less than 2 to 4 times
Poor ×: 4 times or more.

(7) Anti-transparency A seaweed-type composite fiber was used to fabricate a Zokki fabric having a density of 100 strands / 2.54 cm and a weft of 95 strands / 2.54 cm, and was refined at 95 ° C. Subsequently, after a 21% alkali weight loss (dissolving and removing sea components) with a 3 wt% aqueous sodium hydroxide solution at 95 ° C., a final setting was performed after a dyeing step. The obtained fabric sample (sample size: 10 × 10 cm) was affixed to a thick mesh pattern mount, sensory-evaluated by a naked eye method by five skilled persons, and evaluated by a four-step judgment method. △ to △ were acceptable, and × was unacceptable.
◎: Extremely high sheer resistance 性: Large sheer resistance
Δ: Transparency resistant
×: The effect of preventing see-through is small.

(6) Product texture Using the fabric created above, the sensory evaluation by five skilled workers, taking into account the softness, softness, drapability, dryness, sliminess, mild luster and anti-sheer properties. , And evaluated by a four-step determination method. △ to △ were acceptable, and × was unacceptable.
◎: Excellent
〇: good
△: Possible
×: Bad.

(8) Number of fine irregularities Using the cloth created in the above (5), 3 to 10 ultrafine fibers per single field of a group of ultrafine fibers were observed with a scanning electron microscope (SEM: S-3000N manufactured by Hitachi, Ltd.). The number of fine irregularities of 0.1 μm or more was counted from a micrograph taken so that the fiber could be observed, and the number was counted as 40 μm ² and calculated as the number of fine irregularities.

(9) Aspect ratio The length (L) in the fiber axis direction and the width (W) in the direction perpendicular to the fiber axis of the 50 fine irregularities observed in (7) above were measured, and the length relative to the width of the shape was measured. Was calculated as the aspect ratio C.
C = L / W.

(10) Difference in dissolution rate After preparing and weighing about 2 g of each of the polymers used in the sea component polymer and the island component polymer, the following formula was obtained from the weight loss rate when treated with a 3 wt% sodium hydroxide aqueous solution at 95 ° C. for 5 minutes. The dissolution rate difference was calculated.
Weight loss rate of sea component polymer (%: S) = ((weight before treatment) / (weight after treatment)) × 100
Weight loss rate of island component polymer (%: I) = ((weight before treatment) / (weight after treatment)) × 100
Dissolution rate difference = S / I.

(11) Content of inorganic fine particles 0.8 g of a sample polymer was dissolved in 10 mL of O-chlorophenol (OCP) having a purity of 98% or more, and after centrifugation, the content was measured by measuring the weight of the obtained inorganic fine particles. did.
Content of inorganic fine particles (wt%) = (weight of inorganic fine particles obtained by centrifugation / weight of sample polymer before dissolution) × 100.

(12) Long-Term Yarn Stability For each Example, continuous spinning was performed for 10 days, and the long-term yarn-stability of the sea-island composite fiber was evaluated in four steps based on the total number of yarn breakage for 5 days. △ to △ were acceptable, and × was unacceptable.
Excellent ◎: 0 to 5 times Good ○: Less than 6 to 10 times Possible △: Less than 11 to 19 times
Poor ×: 20 times or more.

Example 1
As shown in Table 1, the polyester (A) having an intrinsic viscosity (IV) of 0.66 containing 6.5 wt% of an anatase type TiO ₂ having an average particle size of 0.50 μm was added to the island component polymer, and the intrinsic viscosity (IV) ) Dissolution of the sea component polymer and the island component polymer in the dissolving agent by using the copolyester (B) copolymerized with 7.3 mol% of 5-sodium sulfoisophthalic acid at 0.55 as the sea component polymer and the dissolving agent as the aqueous alkali solution. The speed difference was 50 times. Each of these was melted using an extruder, then weighed so that the weight ratio of the island component polymer was 80 wt% and the weight ratio of the sea component polymer was 20 wt%, and introduced into the pack. The number of islands was 127, and the number of holes was 127. The polymers flowing into the sea-island type composite spinneret 112 merged inside the spinneret to form a composite form in which the island component polymer was included in the sea component polymer, and was discharged from the spinneret. At this time, the yarn discharged from the die at a spinning temperature of 290 ° C. is cooled by an air cooling device, applied with an oil agent, and then wound by a winder at a speed of 1500 m / min so that the spinning draft becomes 180, and 175 dtex-112 filaments are wound. The yarn was stably wound as an undrawn yarn. At this time, the spinning tension was 0.09 cN / dtex by setting the cooling start point at 100 mm from the surface of the die and the lubrication position at 1100 mm, thereby stabilizing the spinning properties.

  Subsequently, the obtained undrawn yarn is sent to a drawing device at a speed of 300 m / min, and drawn at a drawing temperature of 90 ° C. and a draw ratio of about 25 to 40% of residual elongation. After setting, the spinning and drawing steps were performed to obtain a 66dtex-112 filament drawn yarn stably. The sea component polymer was dissolved and removed by immersing the obtained sea-island type composite fiber in a 3 wt% aqueous solution of sodium hydroxide at 95 ° C. The average fiber diameter of the obtained ultrafine single yarn group was 590 nm.

After the two fibers were combined, the fibers were sweet-twisted, woven using warp and weft yarns, and the results of evaluating the obtained woven fabric characteristics are shown in Table 1.
Fine irregularities are expressed on the fiber surface, and a delicate touch, soft touch, and drape are recognized, and further, a dry feeling, anti-transparency, mild gloss can be expressed, and the product texture and product quality Was satisfactory.

Example 2, Reference Example 3
Example 2 was the same as Example 1 except that the content of titanium oxide as inorganic fine particles was changed to 1.0 wt%, and that of Reference Example 3 was changed to 10.0 wt%.

  As shown in Table 1, fine irregularities are expressed on the fiber surface, and delicate touch, soft touch, and drape property are recognized. Further, dryness is imparted, sheer resistance, and mild luster are exhibited. The feeling was able to be expressed and the product texture and product quality were satisfactory.

Examples 4 and 6 , Reference Example 5
In Example 4, the inorganic fine particles were made of zirconia having an average particle size of about 0.11 μm, Reference Example 5 was made of colloidal silica having an average particle size of about 0.04 μm, and Example 6 was made of inorganic fine particles having an average particle size of about 0.10 μm. Example 1 was repeated except that alumina was changed.
The results are shown in Table 1. Example 4 was milder in glossiness, while Reference Example 5 and Example 6 were inferior in see-through resistance and mild glossiness, but were satisfactory in both product texture and product quality.

Comparative Examples 1 and 2
Comparative Example 1 was the same as Example 1 except that the content of inorganic fine particles was changed to 0 wt%, and that of Comparative Example 2 was changed to 12.0 wt%.
The results are shown in Table 1. In Comparative Example 1, there were no fine irregularities on the fiber surface, and none of the see-through resistance, the texture, and the mild glossiness were satisfactory. Furthermore, in Comparative Example 2, the spinnability was extremely poor, and the product quality exhibited a slimy feeling, which was not satisfactory.

Reference Example 7, Example 8
In Reference Example 7, the drawn sea-island composite fiber was 22 dtex-112 filament, the average fiber diameter of the island component after removal of the sea component was 197 nm, and Example 8 was set to 8 islands and 36 holes. The results are shown in Table 1 according to Example 1, except that the average fiber diameter of the island component after removing the sea component was changed to 4640 nm.

Reference Example 9
Reference Example 9 is that the sea-island type composite fiber after drawing is 84dtex-9 filament, the number of islands is 8 and the number of holes is 9 holes, except that the average fiber diameter of the island component after removing the sea component is 9280 nm. The results are shown in Table 1 according to Example 1.

Example 10
The average particle size of 0.50 microns anatase intrinsic viscosity of TiO ₂ contained 6.5wt% (IV) 0.66 polyester (A) the island component polymer, the average particle size of 0.50 microns anatase Copolymer polyester (B) obtained by copolymerizing 7.3 mol% of 5-sodium sulfoisophthalic acid having an intrinsic viscosity (IV) of 0.55 and containing 0.3 wt% of TiO ₂ as a sea component polymer, and a dissolving agent as an aqueous alkali solution The dissolution rate difference between the sea component polymer and the island component polymer in the dissolving agent was 50 times. Each of these was melted using an extruder, then weighed so that the weight ratio of the island component polymer was 80 wt%, the weight ratio of the sea component polymer was 20 wt%, and the fineness of the sea-island composite fiber was 84 dtex, and introduced into the pack. Then, the polymers flowing into the sea-island composite spinning nozzle having 8 islands and 36 holes merged inside the die to form a sea-island shape, and were discharged from the die. At this time, the yarn discharged from the die at a spinning temperature of 290 ° C. is cooled by an air cooling device, and after the oil agent is applied, the yarn is drawn at a speed of 1500 m / min so that the spinning draft becomes 180. After stretching at a temperature of 130 ° C. and a draw ratio of about 25 to 40% of residual elongation, heat setting was performed at 130 ° C., and 84 dtex-36 filament sea-island composite fibers were wound around a drum package with a winder. At this time, the cooling start point was set to 100 mm from the base surface, and the refueling position was set to 1100 mm. The spinning tension was 0.09 cN / dtex.

  The strength of the obtained sea-island composite fiber was 3.5 cN / dtex, the elongation was 35%, and the U% (N) was 0.4%. As a result of observing the cross section of all 36 filaments, the island component of all single yarns was completely covered by the sea component, and the island component was completely separated into the sea component. The area variation of the island components was 2.5%.

  As a result of the evaluation of yarn production for 10 consecutive days, the number of times of yarn breakage in TOTAL for 10 days was stable at one.

  The sea component polymer was dissolved and removed by immersing the sea-island composite fiber in a 3% by weight aqueous solution of sodium hydroxide at 95 ° C. The average fiber diameter of the obtained ultrafine single yarn group was 4600 nm.

  After the two fibers were combined, they were sweet-twisted and used for warp and weft and woven. There is no yarn breakage during twisting and weaving, and fine irregularities are expressed on the fiber surface of the obtained woven fabric, delicate touch, soft tactile sensation, drape property are recognized, and further, imparting dry feeling, preventing Transparency and mild glossiness were exhibited, and the product texture and product quality were satisfactory. Table 2 shows the results.

Examples 11 and 12
Example 10 was followed except that the TiO ₂ content of the sea component was 0.1 wt% and 0.8 wt%, respectively.

  Table 2 shows the physical properties of the obtained sea-island composite fiber. As a result of observing the cross section of all 36 filaments, the island component of all single yarns was completely covered by the sea component, and the island component was completely separated into the sea component.

  As a result of the evaluation of yarn production for 10 consecutive days, the number of times of yarn breakage in TOTAL for 10 days was slightly unstable, 6 times and 8 times, respectively.

  After the two fibers were combined, they were sweet-twisted and used for warp and weft and woven. The obtained woven fabric was found to have good touch, soft touch, and drape, and furthermore, impart dryness, show-through resistance, and mild luster, and were satisfactory in product texture and product quality.

Examples 13 and 14
Example 10 was followed except that the TiO ₂ content of the sea component was 0 wt% and 1.0 wt%, respectively.

  Table 2 shows the physical properties of the obtained sea-island composite fiber. As a result of observing the cross section of all 36 filaments, the island component of all single yarns was completely covered by the sea component, and the island component was completely separated into the sea component.

  As a result of the evaluation of the yarn production for 10 consecutive days, in Example 13, yarn breaks sporadically occurred from the initial stage of the yarn production, and TOTAL yarn breakage was unstable at 45 times for 10 days. Example 14 was stable in the initial stage of yarn production, but yarn breaks sporadically started around the sixth day, and TOTAL yarn breaks were unstable at 22 times for 10 days.

  After the two fibers were combined, they were sweet-twisted and used for warp and weft and woven. Each of the obtained fabrics was fluffy, had a tingling feel, and was somewhat unsatisfied with a crisp luster.

Examples 15 to 18
Example 10 was followed except that the fineness, the number of single yarns, and the number of islands per single yarn of the sea-island type composite fiber were changed as shown in Table 2.

  Table 2 shows the physical properties of the obtained sea-island composite fiber. As a result of observing all the cross sections, the island components of all single yarns were completely covered by the sea component, and the island components were completely separated into the sea component.

  As a result of the evaluation of yarn production for 10 consecutive days, Example 15 showed that TOTAL yarn breakage was slightly unstable at 12 times for 10 days, but at a practical level. Example 16 was stable with three thread breaks. Example 17 was slightly unstable with 18 thread breaks. In Example 18, yarn breakage was frequent during the first three days of spinning, but the stabilization was continued, and TOTAL yarn breakage was at a practical level of 13 times.

  After doubling each fiber, the fibers were sweet-twisted and woven using warp and weft. As a result of evaluation of the obtained woven fabric, in Example 15, good touch, soft touch, and drape property were recognized, and further, impartation of dryness, anti-shedding property, mild glossiness, and a product texture and product quality were obtained. It was satisfactory. In Example 16, the softness was slightly insufficient, and the touch and drape property were slightly unsatisfactory and the slimy feeling was felt, but it was acceptable. In Example 17, fluff was observed in the woven fabric, and dissatisfaction with the touch was recognized, but the level was acceptable. In Example 18, fluff was observed in the woven fabric, dissatisfaction with the touch and glossiness was recognized, and a slight slimy feeling was also felt, but the level was acceptable.

Comparative Example 3
Example 10 was followed except that the fineness, the number of single yarns, and the number of islands per single yarn of the sea-island type composite fiber were changed as shown in Table 2.

  Table 2 shows the physical properties of the obtained sea-island composite fiber. As a result of observing all the cross sections, the island components of all single yarns were completely covered by the sea component, and the island components were completely separated into the sea component.

  As a result of the continuous 10-day yarn production evaluation, the number of yarn breaks was large during 10 days, and TOTAL was 28 times.

  After doubling each fiber, the fibers were sweet-twisted and woven using warp and weft. Many twists and breaks in weaving made it difficult to obtain a woven fabric. The obtained woven fabric was found to have fluff, had a tingling feel and a flickering glossiness, and was at a reject level.

Comparative Examples 4 and 5
Example 10 was followed except that the fineness, the number of single yarns, and the number of islands per single yarn of the sea-island type composite fiber were changed as shown in Table 2.

  The physical properties of the obtained sea-island composite fiber are as shown in Table 2, and Comparative Example 5 had a large area variation of the island component. As a result of observing all the cross sections, the island components of all single yarns were completely covered by the sea component, and the island components were completely separated into the sea component.

  As a result of the yarn evaluation for 10 consecutive days, Comparative Example 4 was stable with one TOTAL yarn break. In Comparative Example 5, the thread breakage was large during 10 days, and the thread breakage was unstable 28 times.

  After doubling each fiber, the fibers were sweet-twisted and woven using warp and weft. As a result of evaluation of the obtained woven fabric, Comparative Example 4 was insufficient in softness, unsatisfactory in touch and glossiness, and was at a reject level. Comparative Example 5 was unsatisfactory because the texture and glossiness were uneven and could not be said to be a high-quality texture.

Comparative Example 6
Example 10 was followed except that the fineness, the number of single yarns, and the number of islands per single yarn of the sea-island type composite fiber were changed as shown in Table 2.

  The physical properties of the obtained sea-island composite fiber are as shown in Table 2, and the area variation of the island component was large. As a result of observing all the cross sections, the island components of all single yarns were completely covered by the sea component, but some of the island components were stuck together.

  As a result of the continuous 10 days of the yarn production evaluation, the yarn breakage occurred frequently in the initial 3 days of the yarn production, and the total yarn breakage was 24 times.

After doubling each fiber, the fibers were sweet-twisted and woven using warp and weft. As a result of the evaluation of the obtained woven fabric, there was unevenness in the touch and softness, and a part that felt firm was recognized. In addition, the glossiness was uneven and the quality was not a high quality texture, and it was rejected.

Examples 19 and 20
Example 10 was followed except that the polymer weight ratio of the island component and the sea component was changed as shown in Table 3.

  The physical properties of the obtained sea-island composite fiber are as shown in Table 3, and the strength of Example 19 was slightly lower. As a result of observing all the cross sections, the island components of all single yarns were completely covered by the sea component, and the island components were completely separated into the sea component.

  As a result of the evaluation of yarn production for 10 consecutive days, Example 19 showed that TOTAL yarn breakage was slightly unstable at 12 times for 10 days, but at a practical level. In Example 20, the thread breakage was six times, which was a level without a problem.

  After doubling each fiber, the fibers were sweet-twisted and woven using warp and weft. As a result of evaluation of the obtained woven fabric, good touch, soft touch, and drape were recognized in both Examples 19 and 20, and further, dryness was imparted, sheer-proofing property, and mild luster were able to be expressed. The quality was satisfactory.

Comparative Example 7
Example 10 was followed except that the polymer weight ratio of the island component and the sea component was changed as shown in Table 3.

  The physical properties of the obtained sea-island composite fiber were as shown in Table 3, and a decrease in strength was observed. As a result of observing all the cross sections, the island components of all single yarns were completely covered by the sea component, and the island components were completely separated into the sea component.

  As a result of the yarn production evaluation for 10 consecutive days, the number of yarn breaks was large throughout the 10 days, and the number of TOTAL yarn breaks for 10 days was unstable at 23 times.

  After doubling each fiber, the fibers were sweet-twisted and woven using warp and weft. As a result of evaluation of the obtained woven fabric, the texture was not good quality and was at a reject level. As a result of detailed analysis of the woven fabric, sea components remained in some of the ultrafine fibers, and poor splitting was observed.

Comparative Example 8
Example 10 was followed except that the polymer weight ratio of the island component and the sea component was changed as shown in Table 3.

  Table 3 shows the physical properties of the obtained sea-island composite fiber. As a result of observing all the cross sections, some island components were stuck together. Some island components were exposed on the fiber surface. As a result, the area variation of the island components was large.

  As a result of the continuous ten-day yarn-making evaluation, the yarn breakage particularly in the latter half of the yarn-making occurred frequently, and the total-day TOTAL yarn breakage was unstable at 28 times.

  After doubling each fiber, the fibers were sweet-twisted and woven using warp and weft. There were many yarn breaks during the sweet twisting and weaving processes, and it was difficult to collect textile samples. The evaluation result of the obtained woven fabric was poor in feel, softness and glossiness, and could not be said to be a good quality texture, and was at a reject level.

Claims (3)

It is an ultrafine fiber having an average particle diameter of 0.10 to 0.50 μm, containing inorganic fine particles selected from titanium oxide, zirconia, and alumina, and having a fiber diameter of 590 to 6000 nm, and having fine irregularities on the surface of the fiber. An ultra-fine polyester fiber having fine irregularities satisfying the following requirements (1) and (2).
(1) The number of small projections 1-15 pieces / 40 [mu] m ²
(2) The size of the fine irregularities is an aspect ratio of 10 or less Ultrafine polyester fiber according to claim 1, characterized in that it contains no machine particulates 1.0 to 8.0 wt%. A woven or knitted fabric in which the fiber according to claim 1 or 2 constitutes at least a part.