JP2009144263A - Water-absorbing quick-drying polyester undrawn fiber and method for producing the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a water-absorbing quick-drying polyester undrawn fiber that has excellent water-absorbing/quick-drying properties and fastness to washing and excellent dyeing fastness and fibrillation resistance. <P>SOLUTION: The water-absorbing quick-drying polyester undrawn fiber having excellent water absorption properties and fastness to washing and excellent dyeing fastness and fibrillation resistance is obtained by making a specific polyester into a polyester undrawn fiber having a sectional shape of the single fiber of W cross section and subjecting the fiber to an alkali reduction treatment so that groove-like micropores in parallel with a fiber axis direction and grooves continuous along the recessed part of the fiber cross section are simultaneously formed on the fiber surface. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a polyester unstretched fiber excellent in water absorption and quick drying. More specifically, the present invention relates to an unstretched polyester fiber excellent in washing durability with water absorption and quick drying performance, and excellent in dyeing fastness, fibril resistance and strength, and a method for producing the same.

Polyester fibers are used in a large amount and in a wide range of fields because they are excellent in various properties such as dimensional stability and elastic recovery properties. Among them, polyester unstretched fibers mainly composed of polyethylene terephthalate are used for their mechanical properties and It is widely used for apparel because of its excellent properties such as chemical properties and wash and wear properties.
However, on the other hand, polyester fiber is poor in water absorption and hygroscopicity compared with other fibers such as cotton, rayon, acetate, wool, etc., so it is used for clothing, especially for innerwear and sportswear. There is a problem that causes uncomfortable wearing due to "steaming" such as when sweating.

In order to solve these problems, a proposal is made to increase the water absorption by capillarity by forming a small gap between the single yarns with a cross-sectional shape of the single yarn of the polyester fiber (Patent Document 1), and a fineness of single yarn fineness of 1 dtex or less. Many proposals using the capillary phenomenon as yarns, and further proposals for increasing water absorption by applying a hydrophilic processing agent after the polyester is made into a knitted fabric (Patent Document 2) have been proposed.
On the other hand, a proposal to increase water absorption by forming fine pores on the fiber surface by melt-spinning polyester mixed with a hydrophilic polymer such as polyethylene glycol or polyalkylene oxide into a fiber, making it into a knitted fabric, and then reducing the weight. (Patent Document 3) has been made.

However, although the surface of the fiber that has been reduced in weight by this method has pores that allow light to be diffusely reflected, the compatibility between the hydrophilic polymer polyalkylene oxide and polyester is low, so the specific surface area of the fiber is increased. It has been found that not enough recesses are formed. Furthermore, in order to improve sufficient water absorption by this method, it is necessary to contain a mixing ratio of the hydrophilic polymer of 5% by weight or more, further 10% by weight or more. It has been found that the light fastness of the knitted fabric is lowered by the influence of the above, and the commercial value is impaired.
In addition, the method of applying a hydrophilic processing agent to the knitted fabric after the modified cross-section yarn or ultrafine fiber is applied to impart water absorbency certainly improves the water absorbency, but the processing agent is knitted by repeated washing. There is a problem that the fabric gradually falls off, and there is a problem that the water absorption performance is lost after almost dropping off.

One way to remedy these shortcomings is to fiberize a polyester copolymerized with an organic sulfonate and polyethylene glycol and then reduce the weight with an alkali compound to form a large number of continuous streak grooves on the fiber surface. The proposal (patent document 4) which gives water absorption and a dry feeling is made | formed.
According to this method, the water absorption performance is improved by the large number of continuous streak-like grooves present on the fiber surface. However, in order to develop sufficient water absorption performance, it is necessary to reduce the alkali weight loss rate by about 30% by weight or more, and the streak-like grooves formed by such high weight loss can be obtained on the fiber surface during long-term use of the knitted fabric. It has been clarified that the fibril resistance becomes a big problem, such as the fluffs and white streaks are generated due to fibrillation of the stripe-shaped grooves due to wear.

Japanese Patent No. 3846955 Japanese Patent Laid-Open No. 11-222721 Japanese Patent No. 3760844 Japanese Patent No. 3293704

  An object of the present invention is to solve the above-mentioned conventional problems, and to provide a water-absorbing quick-drying polyester unstretched fiber excellent in water-absorbing quick-drying washing durability, dyeing fastness and fibril resistance.

  As a result of intensive studies in solving the above-mentioned problems, the present inventors have found that polyester unstretched fibers obtained without stretching a specific polyester are relatively low in the fiber axis direction on the fiber surface due to the alkali weight loss rate. At the same time as the parallel streak-shaped micropores, it can be seen that the concave part of the fiber cross section forms a continuous groove along the fiber length. As a result, it has excellent water-absorbing washing durability and dyeing fastness. It has been found that an unstretched polyester fiber can be provided, and the present invention has been completed.

That is, the present invention
(1) The ethylene terephthalate repeating unit is 90 to 98% by weight, the polyethylene glycol unit having a number average molecular weight of 10,000 to 50,000 is 2 to 10% by weight, the boiling water shrinkage is 2 to 10%, and the elongation at break is 40 to 40%. A fiber obtained by subjecting a 70% polyester unstretched fiber to an alkali weight reduction treatment, having a groove-like micropore parallel to the fiber axis direction on the surface of the fiber, and a fiber specific surface area formed by the micropore However, the ratio (S2 / S1) of the fiber specific surface area S1 (cm ² / g) calculated from the single yarn cross-sectional shape by optical microscope observation and the fiber specific surface area S2 (cm ² / g) measured by the BET method is Polyester unstretched fiber characterized by being 1.5 to 5.0.
(2) The unstretched polyester fiber according to the above (1), wherein the cross-sectional shape of the single yarn of the fiber is W-shaped and the flatness is 2 to 5.
(3) The unstretched polyester fiber according to 1 or 2 above, wherein the fiber is 10 to 40 dtex.
(4) It is obtained by spinning a polyester comprising 90 to 98% by weight of ethylene terephthalate repeating units and 2 to 10% by weight of polyethylene glycol units having a number average molecular weight of 10,000 to 50,000 at a spinning speed of 4500 to 7000 m / min. 2. The polyester undrawn yarn having a boiling water shrinkage of 2 to 10% and a breaking elongation of 40 to 70% is subjected to alkali weight reduction treatment so that the weight loss percentage is 2 to 30% by weight. A method for producing polyester unstretched fibers.
(5) The method for producing an unstretched polyester fiber as described in (4) above, wherein the polyester is a polyester containing 2 to 5% by weight of sodium dodecylbenzenesulfonate.
(6) The method for producing an unstretched polyester fiber according to 4 or 5 above, wherein the polyethylene glycol has a number average molecular weight of 20,000 to 40,000.
(7) The method for producing a polyester unstretched fiber according to any one of 4 to 6 above, wherein an alkali weight reduction treatment is performed at a temperature of 100 ° C. or lower using an alkaline aqueous solution containing alkylbenzyldimethylammonium chloride.
(8) A knitted fabric characterized in that the polyester unstretched fiber according to any one of (1) to (3) is used at least in part.

  The polyester unstretched fiber of the present invention, when used in a knitted fabric, has excellent water-absorbing quick-drying property and washing durability, and has excellent effects of dyeing fastness and fibril resistance. Useful for fabrics and fabrics.

The present invention will be described in detail below.
In order to obtain the polyester unstretched fiber of the present invention, the polyester unstretched fiber subjected to alkali weight loss treatment is a polyester containing 2 to 10% by weight of polyethylene glycol having a number average molecular weight of 10,000 to 50,000 in ethylene terephthalate, It is necessary that 90 to 98% by weight is made of polyester composed of ethylene terephthalate repeating units, the boiling water shrinkage is 2 to 10%, and the elongation at break is 40 to 70%.
It has been found that when the number average molecular weight of polyethylene glycol is as high as 10,000 to 50,000, micropores can be easily formed even with a low alkali weight loss rate.
The reason for this is not clear, but due to the poor compatibility between the hydrophilic polyethylene glycol molecule and ethylene terephthalate, the high molecular weight polyethylene glycol is arranged in the form of a block even in the copolymerization. It is speculated that this is due to the fact that the weight is reduced to a streak.
When the number average molecular weight of polyethylene glycol is as small as less than 10,000, copolymerization with ethylene terephthalate is randomly arranged, so that streak-like micropores are hardly formed even by alkali treatment. When the number average molecular weight of polyethylene glycol exceeds 50,000, copolymerization with ethylene terephthalate does not proceed, but simply becomes a mixture, so that spinnability is hindered, for example, yarn breakage occurs during spinning. The preferred number average molecular weight of polyethylene glycol is 20,000 to 40,000.

When the ratio of polyethylene glycol is less than 2% by weight, micropore formation is hardly caused by alkali treatment, so the alkali weight loss rate needs to be about 30% by weight or more. Since the fibrillation property is extremely lowered, it becomes unusable for practical use.
When the ratio of polyethylene glycol exceeds 10% by weight, the spinnability is hindered, for example, yarn breakage may occur during yarn production. A preferable content of polyethylene glycol is 3 to 8% by weight.
The polyester unstretched fiber of the present invention is produced by a high-speed spinning method described later, and it is necessary that the boiling water shrinkage is 2 to 10% and the elongation at break is 40 to 70%.
In the present invention, an advantage of the unstretched polyester fiber is that the streak-like grooves can be easily formed even with a low alkali weight loss rate. The polyester fiber is usually wound once at an unstretched yarn spun at 1000 to 2000 m / min, or continuously stretched 2 to 5 times without being wound once, so that the breaking elongation is about 40% or less. The drawn fiber is used for the knitted fabric. Since this stretched fiber has a high molecular orientation and a high degree of crystallinity, it has been necessary to perform an alkali weight reduction treatment at a high weight loss rate in order to form a streak-like groove by an alkali weight loss treatment in a subsequent step. As a result, there are drawbacks that the strength of the fiber is lowered and the fibril resistance is lowered.

In the present invention, by using an unstretched polyester fiber having a breaking elongation of 40% or more, it is possible to easily form a streak-like groove even with a very low weight loss rate of 2 to 30% by weight as described later. It is a feature.
The polyester unstretched fiber of the present invention needs to have a boiling water shrinkage of 2 to 10%.
In order to obtain a polyester unstretched fiber having a boiling water shrinkage rate of less than 2%, it is necessary to wind up at a spinning speed exceeding 7000 m / min, and yarn breakage occurs at the time of spinning, making stable production difficult.
When the boiling water shrinkage rate exceeds 10%, the strength of the polyester unstretched fiber becomes less than about 3 cN / dtex, and the mechanical properties deteriorate. Further, there are disadvantages such as excessive shrinkage when the knitted fabric is scoured or dyed. A preferable range of the boiling water shrinkage is 3 to 8%.

The unstretched polyester fiber of the present invention needs to have a breaking elongation of 40 to 70%. In order to obtain a polyester unstretched fiber having a breaking elongation of less than 40%, it is necessary to wind up at a spinning speed exceeding 7000 m / min, and yarn breakage occurs at the time of spinning, making stable production difficult. When the elongation at break exceeds 70%, the strength of the unstretched polyester fiber is less than about 3 cN / dtex, and the mechanical properties are lowered.
A preferable elongation at break is 45 to 70%.
The polyester unstretched fiber of the present invention expresses groove-like micropores parallel to the fiber axis direction on the surface of the fiber by alkali weight reduction treatment of 2 to 30% by weight, and the fiber specific surface area formed by the micropores is The ratio (S2 / S1) of the fiber specific surface area S1 (cm ² / g) calculated from the single yarn cross-sectional shape by optical microscope observation and the fiber specific surface area S2 (cm ² / g) measured by the BET method is 1. It is preferably 5 to 5.0.
The specific surface area is measured by a known BET method as described later.

  In the present invention, the fiber specific surface area ratio S2 / S1 is preferably 1.5 to 5.0. The fiber specific surface area ratio S2 / S1 is an index indicating an increase in specific surface area adjusted by the number of fine holes on the fiber surface and the depth of the holes in the cross-sectional direction. When the fiber specific surface area ratio S2 / S1 is less than 1.5, there are almost no micropores on the fiber surface, and as a result, the water absorption and quick drying performance is insufficient. If the surface has too many micropores and the fiber specific surface area ratio S2 / S1 exceeds 5.0, the water absorption performance increases, but the streak-like grooves become fibrillated due to wear, resulting in fuzz and white streak defects. Furthermore, the strength of the fiber is less than about 3 cN / dtex, which limits the development of sports clothing. Particularly preferred fiber specific surface area ratio S2 / S1 is 2.0 to 4.5. For example, the S2 / S1 ratio of polyester unstretched fibers having excessive fibrils obtained in Patent Document 4 is about 10 or more.

The unstretched polyester fiber of the present invention has a single yarn cross-sectional shape of a W cross section and a single yarn flatness of 2 to 5, and has a microporous groove continuous along the fiber length in at least one concave portion of the cross section. It is preferable.
The cross section of the single yarn is W-shaped, so that the specific surface area of the single yarn itself is large, and the surface of the fiber has groove-shaped micropores parallel to the fiber axis direction, so that it has exceptionally excellent water absorption and quick drying. It became clear that it can be demonstrated. And it is preferable that this flatness is 2-5.
Flatness is the ratio of the short side to the long side of the circumscribed rectangle surrounding the W-shaped cross section. In FIG. 1, the long side b is a value obtained by slowing down the short side a. If the opening angle of each concave portion present in the W-shaped cross section is 100 to 150 degrees, the water absorption and quick drying performance is further improved, which is preferable.

Hereinafter, characteristics obtained by subjecting the polyester unstretched fiber of the present invention to an alkali weight reduction treatment will be described.
FIG. 1 is a schematic view showing the surface of a fiber obtained by subjecting an unstretched polyester fiber of the present invention to an alkali weight loss treatment.
In FIG. 1, it is preferable that at least one of the recesses of the W cross section has a microporous groove continuous along the fiber length. Due to the presence of these continuous grooves, excellent water-absorbing and quick-drying properties can be achieved even if the groove depth, width, length, etc. of the groove-like microholes parallel to the fiber axis direction existing on other parts of the fiber surface are reduced. It can be done.
The continuous grooves of fine holes along the fiber length are preferably present in all of the three concave portions of the W cross section, but if present in at least one, the effects of the present invention are sufficiently achieved. Here, the term “continuous” means that each single yarn constituting the composite fiber may be about several centimeters to several tens of centimeters along the length direction of the fiber. The entire fiber exhibits the action of a substantially continuous groove.

In the present invention, since at least one of the recesses of the W cross section has a groove with a fine hole continuous along the fiber length, water in the knitted fabric can be promptly absorbed by the capillary phenomenon through the groove. Inferred to move.
With this effect, it is presumed that even when repeated washing is performed, the water absorption and quick drying performance is not deteriorated and excellent washing durability is exhibited.
The single yarn surface of the polyester unstretched fiber of the present invention preferably has a large number of groove-shaped fine holes parallel to the fiber axis direction in addition to the groove of the concave portion. The width, length, and number of the grooves are not particularly limited, but if the groove width is 0.1 to 1.5 μm and the length is 3 μm or more, the water absorption and quick drying performance is improved, which is preferable. More preferably, a continuous groove along the fiber length is formed in the concave portion of the W-shaped cross section.
The polyester unstretched fiber of the present invention preferably has a total dtex of 10 to 40 dtex.
When polyester unstretched fibers having a total dtex of 10 to 40 dtex are used for warp and / or weft of a woven fabric, it is possible to obtain a woven fabric having a soft texture in addition to the water-absorbing quick-drying property.

Hereinafter, the manufacturing method of the polyester unstretched fiber of this invention is demonstrated.
The unstretched polyester fiber of the present invention is a polyester containing 2 to 10% by weight of polyethylene glycol having a number average molecular weight of 10,000 to 50,000 in ethylene terephthalate, and 90 to 98% by weight of polyester comprising ethylene terephthalate repeating units is stretched. Without spinning, it is preferable to use a material fiber that has been spun at a spinning speed of 4500 to 7000 m / min.
For the polymerization of the polyester used in the present invention, a method of adding polyethylene glycol in the polymerization step in a known polyethylene terephthalate polymerization method is employed. In the polymerization, 2 to 10% by weight of polyethylene glycol having a number average molecular weight of 10,000 to 50,000 is contained with respect to 90 to 98% by weight of ethylene terephthalate repeating units.

The polyester used in the production of the present invention is more preferably a polyester containing 2 to 5% by weight of sodium dodecylbenzenesulfonate in addition to the above composition.
By containing 2 to 5% by weight of sodium dodecylbenzenesulfonate, the water-absorbing quick drying property is synergistically improved. When the content of sodium dodecylbenzenesulfonate is less than 2% by weight, the synergistic effect of improving the water-absorbing quick-drying is small. When the content exceeds 5% by weight, troubles such as lowering of the yarn-forming property and foaming of the dyeing bath due to sodium dodecylbenzenesulfonate extracted from the unstretched polyester fiber during scouring and dyeing process occur.
As long as the polyester unstretched fiber of the present invention does not impair the effects of the present invention, as other polyester components, acid components such as isophthalic acid, adipic acid, dodecanedioic acid, sulfoisophthalic acid, cyclohexanedimethanol, diethylene glycol, A glycol component such as propylene glycol may be copolymerized. Furthermore, you may contain 3rd components, such as a matting agent, a heat stabilizer, a light stabilizer, an antistatic agent, and a pigment if needed.

The intrinsic viscosity of the polyester used in the present invention is preferably 0.50 to 0.80 (dl / g) from the viewpoint of suppressing yarn breakage during melt spinning.
In the present invention, such polyester is preferably spun at a spinning speed of 4500 to 7000 m / min.
In the melt spinning of the polyester undrawn fiber of the present invention, a known spinning machine having a high-speed winding is used.
If the spinning speed is less than 4500 m / min, the breaking elongation of the unstretched polyester fiber exceeds 70%, and the boiling water shrinkage rate also exceeds 10%. If the spinning speed exceeds 7000 m / min, yarn breakage will occur frequently during spinning, making stable production difficult.
A preferable spinning speed is 5000 to 6500 m / min.
In order to obtain a polyester unstretched fiber having a W cross section of a single yarn, it is discharged from a spinning nozzle having a W-shaped perforated hole attached to a spinning head maintained at 275 to 300 ° C., and is applied to the filament from the circumferential direction. Preferably, cooling air is blown to cool to room temperature, and then oil is supplied and wound.

Hereinafter, the preferable aspect at the time of carrying out the alkali weight reduction process of the knitted fabric fabric obtained using the polyester unstretched fiber of this invention is demonstrated.
The polyester unstretched fiber of the present invention is subjected to an alkali weight reduction treatment after making it into a knitted fabric, using an alkaline aqueous solution containing alkylbenzyldimethylammonium chloride so that the weight loss rate is 2 to 30% by weight at a temperature of 100 ° C. or lower. It is preferable to carry out an alkali weight loss treatment.
In the alkali weight reduction treatment of the polyester unstretched fiber of the present invention, it is preferable to treat with an aqueous solution of low concentration sodium hydroxide or potassium hydroxide. In order to form a streak-like groove on the fiber surface of the polyester unstretched fiber having a sheath core structure with a low-concentration alkaline aqueous solution, it is necessary to treat with an alkaline aqueous solution containing alkylbenzyldimethylammonium chloride. By the combined use of alkylbenzyldimethylammonium chloride, it is possible to easily control the formation of streak-like grooves and suppress the occurrence of excessive fibrils, despite the low weight loss rate with respect to the whole unstretched polyester fiber.
In particular, by making it W-shaped, it becomes possible to form a groove of a fine hole continuous along the fiber length in at least one recess. It is not clear why the microporous grooves continuous along the fiber length are formed in at least one of the recesses of the W cross section by the alkali weight loss treatment specified in the present invention. It is presumed that the structure is suppressed only in the recesses and that polyethylene glycol is contained, and the alkali weight loss rate in the recesses is increased to selectively reduce the alkali.

A compound having an alkyl group size of C12 to C18 in alkylbenzyldimethylammonium chloride can be used. As a specific example having a C12 lauryl group, DYK-1125 (manufactured by Yushi Kogyo Co., Ltd.) and the like, and as a specific example having a C18 stearyl group, DXK-10N (one company Yushi Kogyo Co., Ltd.). Manufactured).
The use concentration of alkylbenzyldimethylammonium chloride is preferably in the range of 0.25 to 1.5 g / l. When the concentration used is 0.25 g / l or less, the formation of the streak groove is light and the streak groove formation between single yarns varies widely, and the specific surface area ratio of the present invention cannot be obtained and the water-absorbing quick-drying performance Durability may be insufficient. On the other hand, if the concentration used is higher than 1.5 g / l, the hydrolysis reaction is promoted, and it may be difficult to control to a desired weight loss rate.
The concentration of the alkali agent used in combination is preferably 2 to 6 g / l because it is easy to control the weight loss rate of the whole unstretched polyester fiber.
The treatment temperature is 100 ° C. or less, preferably 95 ° C., and the treatment time is preferably in the range of 5 to 30 minutes.

The alkali weight loss rate of the present invention is preferably 2 to 30% by weight.
If the alkali weight loss rate is less than 2% by weight, the formation of streak-like grooves is insufficient, the specific surface area specified in the present invention cannot be obtained, and the washing durability of the water-absorbing quick-drying performance is insufficient. In addition, when the alkali weight loss rate exceeds 30% by weight, the specific surface area obtained is improved and the water-absorbing quick-drying performance is improved. However, the fibrillation due to single yarn breakage, the wear resistance is reduced, and the appearance quality of the woven or knitted fabric associated therewith Decrease and burst strength decrease. By controlling the preferred alkali weight loss rate to 5 to 25% by weight, more preferably 10 to 20% by weight, the balance between washing durability of water absorption and quick drying performance and fibril resistance becomes the best.

The form of the unstretched polyester fiber of the present invention may be long fibers or short fibers, and may be uniform or thick in the length direction. And as the form of the yarn in which the fiber is processed, a spun yarn such as a ring spun yarn, an open-end spun yarn, an air jet fine spun yarn, a sweet twisted yarn to a strongly twisted yarn, a false twisted yarn (including POY drawn false twisted yarn) ), Air injection processed yarn, indented processed yarn, knitted knitted yarn, and the like.
Furthermore, you may mix the polyester unstretched fiber of this invention, and other polyester unstretched fibers. In this case, it is preferable that the proportion of polyester unstretched fibers in the knitted fabric is 20% or more.

As other fibers used by mixing, spandex, polyamide, cellulose fiber, and the like may be mixed.
Examples of blended products include blended blends (blend cotton, fleece blends, sliver blends, core yarns, silo spans, silofills, hollow spindles, etc.), entangled blends, twists, design twists, coverings (single, double), compound false twists ( Examples thereof include simultaneous false twisting, first twist false twisting, elongation difference false twisting, phase difference, post-mixing after false twisting, mixed feeding by two-feed (simultaneous feed or feed difference) air injection processing, and the like.
On the other hand, as an example of the knitted fabric, there is a general knitting knitting fabric. For example, in the knitting, the yarns are aligned and fed, or double knitted fabric (for example, double circular knitting machine, double flat knitting machine, double raschel) In a warp knitting machine, there is a method of feeding yarns on the front surface and / or the back surface, respectively. In cross weaving, one is used for the warp and the other is used for the weft. In the warp and / or weft, both are alternately arranged by warping or weft insertion, and in the brushed fabric or pile fabric, one constitutes the ground structure, The other constitutes a brushed part and a pile part or mixes them to form a ground structure, a raised part, and the like. In the double woven fabric, the front surface and / or the back surface are configured or mixed, respectively. Further, a combination of these various yarn stages and a combination on the machine may be combined.

Examples The present invention will be described more specifically with reference to examples, but the present invention is not limited to these examples. In addition, the measuring method of the characteristic value used by this invention is shown below.
(1) Flatness Flatness was calculated | required from ratio of the short side a of the circumscribed rectangle of a single yarn cross section, and the long side b so that it might illustrate in FIG.
Flatness = long side b / short side a

(2) Fiber specific surface area ratio The fiber specific surface area S2 (cm ² / g) of the unstretched polyester fiber was measured 5 times with a BET specific surface area meter (manufactured by Mounttech), and the average value was used. It was.
The fiber specific surface area S1 (cm ² / g) calculated from the single yarn cross-sectional shape was obtained by measuring the circumference of the single yarn cross section using an optical microscope.
The ratio of the specific fiber surface area was determined by the following formula.
Ratio of fiber specific surface area = S2 / S1

(3) Water absorption
The fabric was attached to a embroidery round frame with a diameter of 15 cm, and 0.1 ml of a water-soluble blue dye solution (containing 0.005 wt% of CI Acid Blue 62) was dropped on the fabric surface. The diffusion area is obtained from the following equation.
Water absorption diffusion area (cm ² ) = [vertical diameter (cm) × horizontal diameter (cm)] × π ÷ 4
Measurement was performed 5 times for each sample, and the average water absorption and diffusion area was determined.
Evaluation of washing resistance is 1 g / 10 liter of detergent with a commercially available fully automatic washing machine, bath ratio 1: 1000.
After repeating 100 times, the same measurement of the water absorption and diffusion area was performed.
According to this measurement, if the water absorption diffusion area is 10 cm ² or more, the water absorption is good.

(4) Quick-drying The fabric (10 cm square) was sufficiently wetted with water, dehydrated with a dehydrator at 2000 rpm for 1 minute, the weight of the fabric was measured, the water content was calculated, and the relative humidity was 65% at a temperature of 20 ° C. In this environment, the time (minutes) until the moisture content of the fabric reached 2% (moisture content that felt dry) was measured.
The washing resistance was measured in the same manner as the water absorption measurement.
In this measurement, if the drying time is 25 minutes or less, it has good quick drying properties.
(5) Dye fastness The dyed product was evaluated according to JIS-L-0846. The change color of the test piece and the degree of contamination of the attached white cloth piece were judged by comparing with the gray scale for change color and the gray scale for contamination, respectively.
In this measurement, if it is grade 3 or higher, it has practically good dyeing fastness.

(6) Fibril resistance The dyed product was evaluated according to JIS-L-1096. The number of friction was set to 4000 times, and the surface after friction was classified into 5 grades and judged.
In this measurement, if it is 4th grade or higher, it has good fibril resistance.
(7) Breaking elongation and breaking strength Measured based on JIS-L-1013.

(8) Spinning Stability One day of melt spinning-continuous stretching was carried out for each example using a melt spinning-continuous stretching machine equipped with an 8-end spinneret per spindle.
From the number of occurrences of yarn breakage during this period and the occurrence frequency of fluff existing in the obtained composite fiber package (ratio of the number of fluff generation packages), the determination was made as follows.
◎; Yarn break 0 times, fluff generation package ratio 5% or less ○; Thread breakage 2 times or less, fluff generation package ratio less than 10% ×; Yarn break 3 times or more, Fluff generation package ratio 10% or more

[Examples 1-5, Comparative Examples 1-2]
In this example, the effect of the alkali weight loss treatment on polyester unstretched fibers will be described.
Polyethylene glycol having a number average molecular weight of 20,000 is copolymerized by 4% by weight, and at the same time, an intrinsic viscosity [η] containing 2% by weight of sodium dodecylbenzenesulfonate is 0.62 (dl / g). It is extruded from a nozzle having 30 nozzle holes at a spinning temperature (spin head temperature) of 280 ° C., blown with cooling air of 0.8 m / second from the circumferential direction to cool to room temperature, and then refueling and stretching. The polyester unwinding fiber of 34 dtex / 18 filament was obtained by winding up at 5000 m / min.
The obtained polyester unstretched fiber has a W-shaped single yarn cross section, a recess opening angle of 130 degrees, a flatness of 3.8, a boiling water shrinkage of 5%, a breaking elongation of 55%, and a breaking strength. It was 3.3 cN / dtex.

From the obtained polyester unstretched fiber, a false twisted yarn was obtained by a conventional method using a two-heater false twister. Using this false twisted yarn, a smooth knitted fabric was prepared on a 33-inch knitting machine under normal knitting conditions. The knitted fabric basis weight was 220 g / m ² .
This knitted fabric is scoured at 80 ° C., pre-set at 190 ° C., subjected to alkali weight loss treatment under the following conditions, and adjusted so that the alkali weight loss rate is as shown in Table 1. Weight loss processing was performed with a flow dyeing machine.
Alkali weight loss processing conditions Alkali: Sodium hydroxide 4 g / liter Laurylbenzyldimethylammonium chloride: DYK-1125
(On the other hand, manufactured by Yushi Co., Ltd.) 1.2 g / liter
Bath ratio: 1:25
Processing temperature: 95 ° C
After the treatment, it was washed with water, washed with anion activator (7WA-62; manufactured by Yushi Kogyo Co., Ltd.) 2 g / liter at 60 ° C. for 10 minutes, and then washed with water.

Next, it dye | stained on the following dyeing | staining conditions.
Dyeing conditions Dye: Dianics Blue S-2R 2.2% omf
(Dystar)
Auxiliary agent: Nikka Sun Salt RM-340 (manufactured by Nikka Chemical Co., Ltd.)
0.5g / liter
Acetic acid: 0.5 cc / liter Sodium acetate: 1 g / liter Bath ratio: 1:25
Dyeing temperature, time: 130 ° C., 30 minutes After dyeing is completed, the dyeing residual liquid is discharged from the dyeing machine, water is added to the dyeing machine, the temperature is raised to 80 ° C., and the following chemicals are added to the following. A reducing cleaning bath having a concentration was prepared, and reducing cleaning was performed at 80 ° C. for 20 minutes.
Hydrosulfite 2 g / liter Caustic soda 2 g / liter Bisnole UP-10 (manufactured by Yushi Co., Ltd.) 0.5 g / liter Bath ratio: 1:25

After this reduction cleaning, the residual liquid was discharged, the dyed product was rinsed with warm water and water, dehydrated and dried, and then set by dry heat at 130 ° C. for 45 seconds to finish.
Table 1 shows the evaluation results of the water-absorbing diffusion area, dehydration drying property, dyeing fastness, and fibril resistance of the finished dyed fabric.

When the obtained dyed fabric was observed with an electron microscope at a magnification of 1800, streaks having a width of 0.2 to 0.5 μm and a length of 3 μm or more were formed on the surface of the polyester unstretched fiber in the fiber axis direction. A continuous fine streak-like groove having a width of 0.2 to 0.6 μm was observed in the concave portion of the W cross section.
Examples 1 to 5 had excellent water absorption quick-drying property, washing durability, dyeing fastness and fibril resistance.
In Comparative Example 1, since the alkali weight loss rate was as small as 1% by weight, the formation of micropores was insufficient and the water absorption and quick drying property was insufficient.
Comparative Example 2 had poor fibril resistance due to the excessive alkali weight loss of 40% by weight.

[Examples 6-7, Comparative Examples 3-6]
In this example, the effects of the number average molecular weight of polyethylene glycol, the content in polyester, and the content of sodium dodecylbenzenesulfonate will be described.
As shown in Table 2, polyester unstretched fibers were obtained at a spinning speed of 5000 m / min with different number average molecular weight and content. Table 2 shows the spinnability during yarn production and the physical properties of the obtained polyester unstretched fiber.
Further, Table 2 shows the water-absorbing quick-drying property, dyeing fastness and fibril resistance of a fabric obtained by subjecting the obtained polyester unstretched fiber to an alkali weight reduction treatment after knitting as in Example 2.

Example 6 and Example 7 had good water absorption quick-drying property, dyeing fastness, and fibril resistance.
In Comparative Example 3, since the number average molecular weight of polyethylene glycol was outside the scope of the present invention, the formation of micropores on the fiber surface was poor even with the alkali reduction treatment, and water absorption was not obtained.
Comparative Example 4 had poor water absorption due to the low content of polyethylene glycol.
Comparative Examples 5 and 6 had poor spinnability and poor dyeing fastness and fibril resistance because the polyethylene glycol content or number average molecular weight was outside the scope of the present invention.

[Examples 8-11, Comparative Examples 7-8]
In this example, the effect of spinning speed will be described in producing polyester unstretched fibers.
In Example 2, polyester unstretched fibers were obtained by varying the spinning speed as shown in Table 3.
Table 3 shows the spinnability, boiling water shrinkage, elongation at break, and strength at break of the obtained polyester unstretched fiber.

Examples 8 to 11 had good spinnability and excellent water-absorbing quick-drying property, dyeing fastness and fibril resistance after alkali weight loss treatment.
In Comparative Example 7, the spinning speed was low, the boiling water shrinkage ratio, breaking elongation, and breaking strength of the obtained polyester unstretched fiber were outside the range of the present invention, and the resulting knitted fabric was also hard.
In Comparative Example 8, since the spinning speed was high, the spinning property was poor, and stable production was difficult.

[Example 12]
In this example, the effect of using unstretched polyester fibers having a reduced total dtex in a woven fabric will be described.
In the same manner as in Example 1, a 34 dtex / 18 filament polyester unstretched fiber was obtained.
The polyester unstretched fiber obtained had a boiling water shrinkage of 4.8%, a breaking elongation of 57%, a breaking strength of 3.3 cN / dtex, and a flatness of 3.8.
Using this polyester unstretched fiber, a plain fabric with a raw machine warp density of 160 / inch and a weft density of 138 / inch is scoured and preset in the same manner as in Example 1, and then subjected to a weight reduction treatment to an alkali weight loss rate of 7% by weight. After doing, dyeing finish was performed. A plain fabric having a warp density of 163 yarns / inch and a weft density of 154 yarns / inch was obtained.
The obtained woven fabric has a smooth surface property while having fine pores on the fiber surface, the specific surface area ratio S2 / S1 is 2.5, and the water absorption and diffusion area after 100 washings is 16 (cm ² ). The woven fabric was excellent in dehydration rate 15 (min), water fastness, discoloration grade 4 and fibril resistance grade 5.

It is a schematic diagram which shows the single yarn which carried out the alkali weight reduction process of the polyester unstretched fiber of this invention.

Claims (8)

The ethylene terephthalate repeating unit is 90 to 98% by weight, the polyethylene glycol unit having a number average molecular weight of 10,000 to 50,000 is 2 to 10% by weight, the boiling water shrinkage is 2 to 10%, and the elongation at break is 40 to 70%. A fiber obtained by subjecting a polyester unstretched fiber to an alkali weight loss treatment, having a groove-like micropore parallel to the fiber axis direction on the surface of the fiber, and a fiber specific surface area formed by the micropore is optical. The ratio (S2 / S1) of the fiber specific surface area S1 (cm ² / g) calculated from the cross-sectional shape of the single yarn by microscopic observation and the fiber specific surface area S2 (cm ² / g) measured by the BET method is 1.5. Polyester unstretched fiber characterized by being -5.0.   The unstretched polyester fiber according to claim 1, wherein the fiber has a W-shaped single yarn cross-sectional shape and a flatness of 2 to 5.   The said fiber is 10-40 dtex, The polyester unstretched fiber of Claim 1 or 2 characterized by the above-mentioned.   Boiling water shrinkage obtained by spinning a polyester comprising 90 to 98% by weight of ethylene terephthalate repeating units and 2 to 10% by weight of polyethylene glycol units having a number average molecular weight of 10,000 to 50,000 at a spinning speed of 4500 to 7000 m / min. 2. The polyester undrawn yarn according to claim 1, wherein an unstretched polyester yarn having an elongation of 2 to 10% and a breaking elongation of 40 to 70% is subjected to an alkali weight reduction treatment so that the weight loss rate is 2 to 30% by weight. A method for producing drawn fibers.   The method for producing an unstretched polyester fiber according to claim 4, wherein the polyester is a polyester containing 2 to 5% by weight of sodium dodecylbenzenesulfonate.   The number average molecular weight of the said polyethylene glycol is 20,000-40,000, The manufacturing method of the polyester undrawn fiber of Claim 4 or 5 characterized by the above-mentioned.   The method for producing an unstretched polyester fiber according to any one of claims 4 to 6, wherein an alkali weight reduction treatment is performed at a temperature of 100 ° C or lower using an aqueous alkali solution containing alkylbenzyldimethylammonium chloride.   A knitted fabric using at least part of the unstretched polyester fiber according to any one of claims 1 to 3.

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