JP2008150729A - Water-absorbing/quick-drying polyester conjugated fiber and method for producing the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a water-absorbing/quick-drying polyester conjugate fiber excellent in water-absorbing/quick-drying property and washing durability, also excellent in dyed color fastness, fibril-proof property and strength. <P>SOLUTION: This sheath core type polyester conjugate fiber is provided by having grooves like microspores in parallel to fiber axis direction on the surface of the fiber, a fiber specific surface area formed by the microspores within a specific range, 2-5 flatness in a cross section W and the grooves of continued microspores along fiber length at least at a recessed part of the cross section, and containing 0.05-2.0% polyethylene glycol in the fiber. The method for producing the polyester conjugate fiber is provided by forming a sheath component of the sheath core type conjugate fiber by a polyester obtained by blending a specific copolyester A with a polyester B, then performing an alkali reduction treatment under a specific condition to form the grooves like microspores in parallel to the fiber axis direction on the fiber surface and at the same time the continuous grooves along the fiber length at the recessed part of the fiber cross section. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a polyester composite fiber excellent in water absorption and quick drying, and more particularly relates to a polyester composite fiber excellent in washing durability of water absorption and quick drying performance, and excellent in dyeing fastness, fibril resistance and strength.

Polyester fibers are used in a wide range of fields because they are excellent in various properties such as dimensional stability and elastic recovery. Among them, polyester fibers mainly composed of polyethylene terephthalate have mechanical properties and chemical properties. Due to its excellent properties such as properties and wash and wear properties, it is widely used in clothing applications.
However, on the other hand, polyester fibers are less water-absorbing and hygroscopic than other fibers such as cotton, rayon, acetate, wool, etc., so they are used for clothing, especially innerwear and sportswear. There is a problem in that it causes uncomfortable wearing due to "steaming" when sweating.
In order to solve these problems, a proposal for increasing the water absorption by capillarity by creating a small gap between the single yarns with the cross-sectional shape of the single yarn of the polyester fiber as a modified cross section (Patent Document 1), and the single yarn fineness of 1 dtex or less A number of proposals using the capillary phenomenon as ultrafine yarn, 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) are proposed.

On the other hand, polyester blended with a hydrophilic polymer such as polyethylene glycol or polyalkylene oxide is melt-spun into a fiber, made into a knitted fabric, and then reduced in weight to form micropores on the fiber surface, thereby absorbing water. There has been a proposal to increase (Patent Document 3).
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 hydrophilic polymer mixing ratio of 5% by weight or more, preferably 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 the hydrophilic processing agent after applying the above-mentioned atypical cross-section yarn or ultrafine fiber to the knitted fabric to impart water absorbency certainly improves the water absorption, but the processing agent is knitted by repeated washing. There has been a problem that the fabric gradually falls off, and the water absorption performance is no longer impaired after almost falling off.
Furthermore, after fiberizing polyester obtained by copolymerization of organic sulfonate and polyethylene glycol, weight loss treatment with an alkali compound is performed to form a large number of continuous streak grooves on the fiber surface, thereby imparting water absorption and dry feeling. A proposal (Patent Document 4) has been made.
According to this method, although the water absorption performance is improved by a large number of continuous streak grooves existing on the fiber surface, the streak grooves on the fiber surface become fibrillated due to wear during long-term use of the knitted fabric, and flaws and white streak defects It has become clear that fibril resistance is a major issue.

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 provide a water-absorbing quick-drying polyester composite fiber that solves the above-mentioned conventional problems, is excellent in water-absorbing quick-drying washing durability, and is excellent in dyeing fastness, fibril resistance and strength. .

  As a result of intensive studies in solving the above-mentioned problems, the present inventors have obtained a sheath component of a sheath-core type composite fiber in which a single yarn cross-sectional shape is a W cross-section of a polyester obtained by blending a specific copolymer polyester A with a polyester B. Then, by performing alkali weight loss treatment under specific conditions, a groove-like microhole parallel to the fiber axis direction is formed on the fiber surface, and a continuous groove along the fiber length is formed in the concave portion of the fiber cross section. Thus, the present inventors have found that a polyester composite fiber excellent in water-absorbing washing durability and excellent in color fastness and strength can be provided, and the present invention has been completed.

That is, the first of the present invention is a sheath-core type polyester composite fiber, which has groove-like micropores parallel to the fiber axis direction on the surface of the fiber and satisfies the following requirements (1) to (3). A polyester composite fiber, characterized in that
(1) The fiber specific surface area formed by the micropores is the fiber specific surface area S1 (cm ² / g) calculated from the cross-sectional shape of the single yarn by optical microscope observation, and the fiber specific surface area measured by the BET method. The S2 (cm ² / g) ratio (S2 / S1) is 1.5 to 5.0,
(2) The cross-sectional shape of the single yarn is a W cross-section, the flatness of the single yarn is 2 to 5, and has a groove of a fine hole continuous along the fiber length in at least one concave portion of the cross-section.
(3) The content of polyethylene glycol contained in the fiber is 0.05 to 2.0% by weight.
A second invention of the present invention is a method for producing a sheath-core polyester composite fiber, wherein the core component is made of polyester B, and the sheath component is 2 to 10% by weight of polyethylene glycol having a number average molecular weight of 4000 to 50,000. It consists of polyester A and polyester B which are copolymerized, and a polyester component in which the mixing ratio of the polyester A in the sheath is 10 to 50% by weight. Using the aqueous alkali solution containing benzyldimethylammonium chloride, the method for producing the first polyester conjugate fiber, wherein the alkali weight loss treatment is performed so that the weight loss rate is 4 to 35% by weight at a temperature of 100 ° C. or lower; It is.

Hereafter, the effect of the component requirement of this invention is demonstrated.
The requirements (1) to (3) in the sheath-core polyester composite fiber of the present invention are as follows.
The specification of the specific surface area by the micropores in requirement (1) is an important requirement for increasing the water absorption quick-drying property while suppressing excessive fibrils and maintaining fibril resistance and strength.
Although the groove | channel which continues along the fiber length formed in the recessed part of the W cross section of the requirement (2) does not form a micropore excessively and it was restrained to the limited specific surface area, a water absorption quick-drying property Is an important requirement to increase
The specification of the polyethylene glycol content in requirement (3) is an important requirement for enhancing the affinity between micropores and water and maintaining dyeing fastness.

In the present invention, by simultaneously satisfying the requirements of (1), (2) and (3), the water-absorbing washing durability is excellent, and the dyeing fastness, fibril resistance and strength are excellent. It exhibits an excellent effect.
In the method for producing the sheath-core type polyester composite fiber of the present invention, the specification of the polyester A used as the core component is an important requirement for forming groove-like micropores on the fiber surface by the alkali weight loss treatment. Specification of blend ratio of polyester B and polyester B is an important requirement for suppressing excessive fibrils, and specification of sheath core content is important for controlling polyethylene glycol content after alkali weight loss treatment. It is a requirement, and the specification of the alkali weight reduction treatment condition is an important requirement for forming a continuous groove along the fiber length in the concave portion of the W-shaped cross section.

  The polyester conjugate fiber of the present invention, when used in a knitted fabric, has excellent water absorption quick-drying and its washing durability, and has excellent effects in dyeing fastness, fibril resistance and strength. It is useful for knitted fabrics for innerwear.

The present invention will be described in detail below.
The polyester composite fiber according to the first aspect of the present invention has groove-like micropores parallel to the fiber axis direction on the surface of the fiber, and (1) the fiber specific surface area formed by the micropores is observed with an optical microscope. 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 the fiber and the fiber specific surface area S2 (cm ² / g) measured by the BET method is 1.5 to 5 0.0, and (2) the cross-sectional shape of the single yarn is a W cross-section, the flatness of the single yarn is 2 to 5, and at least one concave portion of the cross-section has a groove with a fine hole continuous along the fiber length. (3) The polyethylene glycol content in the fiber is 0.05 to 2.0% by weight.
The specific surface area is measured by a conventionally known BET method as described later.

  In the present invention, it is important that the fiber specific surface area ratio S2 / S1 is 1.5 to 5.0. The fiber specific surface area ratio S2 / S1 is an index 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, and pills and white streaks are generated. Furthermore, the strength of the fiber is less than about 3 cN / dtex, which limits the development of sports clothing. A preferable fiber specific surface area ratio S2 / S1 is 2.0 to 4.5. For example, the S2 / S1 ratio of the polyester fiber having excessive fibrils obtained in Patent Document 4 is about 10 or more.

The polyester conjugate fiber of the present invention has a cross-sectional shape of a single yarn having a W cross-section and a flatness of the single yarn of 2 to 5, and has at least one concave portion of the cross-section having a groove of fine pores along the fiber length. It is necessary to be.
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. The single yarn cross section is W-shaped, and this flatness is required to be 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.

It is necessary that at least one of the recesses of the W cross section has a continuous microporous groove 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. You can do it.
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 approximately several centimeters to several tens of centimeters along the length direction of the fiber. By doing so, the effect of the substantially continuous groove | channel is exhibited as the whole fiber.

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.
And by this effect, even if it repeats washing, it is guessed that a water absorption quick-drying performance does not fall and it exhibits the outstanding washing durability.
On the surface of the single yarn of the polyester composite fiber of the present invention, it is necessary to have groove-shaped fine holes parallel to the fiber axis direction in addition to the grooves of the recesses. 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.

In FIG. 1, the schematic diagram of the single yarn of the polyester composite fiber of this invention is shown.
The polyester composite fiber of the present invention needs to have a polyethylene glycol content of 0.05 to 2.0% by weight. When the polyethylene glycol content is less than 0.05% by weight, even if micropores are present on the fiber surface, the water-absorbing quick-drying washing durability is insufficient. When the content of polyethylene glycol exceeds 2.0% by weight, dyeing fastness decreases. The polyester composite fiber of the present invention is greatly characterized in that the water-absorbing and quick-drying performance is synergistically improved due to the presence of a minute amount of polyethylene glycol and the presence of fine pores. A preferable content of polyethylene glycol is 0.1 to 1.0% by weight.
By reducing the content of polyethylene glycol to such a small amount, the decrease in light fastness, which is a problem in Patent Document 3, is solved.
The polyethylene glycol contained in the fiber may be either copolymerized or blended, but is preferably copolymerized for the purpose of improving washing durability.

Below, the manufacturing method of the polyester composite fiber which is 2nd invention of this invention is demonstrated.
The second of the present invention is a method for producing a sheath-core type polyester composite fiber, wherein the core component is made of polyester B, and the sheath component is copolymerized with 2 to 10% by weight of polyethylene glycol having a number average molecular weight of 4,000 to 50,000. Polyester A is composed of a polyester component blended in an amount of 10 to 50% by weight based on the sheath component, and both are melt-combined and spun into fibers by drawing and heat treatment, and then an alkaline aqueous solution containing alkylbenzyldimethylammonium chloride is used. A method for producing a polyester composite fiber, characterized in that an alkali weight loss treatment is performed at a temperature of not higher than ° C.
The polyester A used for the production of the polyester fiber of the present invention is characterized in that 2 to 20% by weight of polyethylene glycol having a number average molecular weight of 4000 to 50,000 is copolymerized.

As will be described later, such polyester A is polymer blended with polyester B and fiberized as a sheath component of a composite fiber, and then subjected to alkali weight loss treatment under specific conditions, thereby forming a groove-like shape parallel to the fiber axis direction. Micropores can be formed.
When the number average molecular weight of the polyethylene glycol is less than 4000, the compatibility with the polyester B is improved, and even if the weight reduction treatment is performed, the increase in the specific surface area becomes poor and the object of the present invention is not achieved. When the number average molecular weight exceeds 50,000, the compatibility with the polyester B becomes poor, and the yarn breakage during spinning and the strength of the composite fiber decrease. The preferable range of the number average molecular weight of polyethylene glycol is 6000 to 20,000.
When the copolymerization ratio of the polyethylene glycol is less than 2% by weight, the compatibility with the polyester B is improved, and even if the weight reduction treatment is performed, the increase in the specific surface area becomes poor and the object of the present invention is not achieved. When the copolymerization ratio exceeds 20% by weight, the heat resistance of the polyester B is poor, the yarn breakage and light fastness during melt composite spinning are lowered, and the object of the present invention is not achieved. A preferable copolymerization ratio is 3 to 8% by weight.

The most preferable composition of the polyester A is that 4 to 6% by weight of polyethylene glycol having a number average molecular weight of 6000 to 20,000 is copolymerized.
Polyester A and / or polyester B are preferably composed of ethylene terephthalate repeating units, but may be trimethylene terephthalate, tetramethylene terephthalate, or the like.
In addition, as long as the effects of the present invention are not impaired, other polyester components include acid components such as isophthalic acid, adipic acid, dodecanedioic acid, sulfoisophthalic acid, and cyclohexanedimethanol, and glycol components such as diethylene glycol and propylene glycol. It 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, as needed.
The intrinsic viscosity of polyester A and / or polyester B used in the present invention is preferably 0.50 to 0.80 from the viewpoint of suppressing yarn breakage during melt composite spinning.

In the sheath-core polyester composite fiber of the present invention, the blending ratio of the sheath component to the core component is preferably 10/90 to 50/50. If the ratio of the sheath component is less than 10%, the polyethylene glycol component in the sheath component may fall off due to the alkali weight loss treatment, and the water absorption and quick drying performance may be insufficient. When the ratio of the sheath component exceeds 50%, the strength of the polyester composite fiber may be lowered to about 2 cN / dtex or less, and the mechanical performance of the knitted fabric may be lowered. A preferable blending ratio of the sheath component and the core component is 20/80 to 40/60.
In the production of the polyester fiber of the present invention, it is preferable to treat with a low-concentration sodium hydroxide or potassium hydroxide aqueous solution in the alkali weight loss treatment. In order to form a streak-like groove on the fiber surface of the polyester composite 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. The combined use of alkylbenzyldimethylammonium chloride makes it possible to control the formation of streak-like grooves easily despite the low weight loss rate with respect to the entire polyester composite fiber, and to suppress the generation of excessive fibrils. In particular, it has become possible to form a groove with a continuous micropore along the fiber length in at least one recess of the W cross section.

As the size of the alkyl group in the alkylbenzyldimethylammonium chloride, a compound having 12 to 18 carbon atoms can be used. As a specific example having a lauryl group having 12 carbon atoms, DYK-1125 (trade name) manufactured by Otsuka Oil Co., Ltd., and the like, as a specific example having a stearyl group having 18 carbon atoms, DXK-10N (brand name) manufactured by the company etc. are mentioned.
The use concentration of alkylbenzyldimethylammonium chloride is preferably in the range of 0.25 to 1.5 g / l. When the concentration used is less than 0.25 g / l, 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 use concentration exceeds 1.5 g / l, the hydrolysis reaction is accelerated, and it may be difficult to control the desired weight loss rate.
The alkali agent concentration of the alkaline aqueous solution used in combination is preferably 2 to 6 g / l because it is easy to control the weight loss rate of the entire polyester composite 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 required to be 4 to 35% by weight.
If the alkali weight loss rate is less than 4% 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 35% by weight, the specific surface area obtained is improved, and the water-absorbing quick-drying performance is improved. However, the wear resistance is reduced due to fibrillation due to single yarn breakage, 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 10 to 25% by weight, more preferably 10 to 20% by weight, the balance between washing durability of water absorption and quick drying performance and wear resistance becomes the best.
The reason for the formation of a continuous microporous groove along the fiber length in at least one of the recesses of the W cross section by the alkali weight reduction treatment specified in the present invention is not clear, but it is a sheath-core type composite fiber Therefore, it is presumed that the fiber structure such as the degree of crystallinity 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.
In the melt composite spinning of the polyester composite fiber of the present invention, a known composite spinning machine can be employed. As the spinning method, there are employed a method in which an undrawn yarn is once wound and then subjected to a drawing heat treatment, or a spinning direct drawing method in which the undrawn yarn is continuously wound and then wound without being wound once.

The polyester composite fiber of the present invention is not particularly limited, but is preferably a fiber having a total fineness of 30 to 250 dtex. Moreover, it is preferable that it is a fiber with a single yarn fineness of 0.1-20 dtex. The form of the fibers 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 composite fiber of this invention, and another polyester fiber. In this case, the proportion of the polyester composite fiber in the knitted fabric is preferably 20% by weight or more.
As other fibers to be used in combination, spandex, polyamide fiber, cellulose fiber and the like are mixed.

Examples of blended products include blended blends (blend cotton, fleece blends, sliver blends, core yarns, silo spans, silofills, hollow spindles, etc.), entangled blends, twisted yarns, design twisted yarns, coverings (single and 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 in which yarns are fed to 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 may be configured or mixed for use. 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 polyester composite fiber was measured five times using 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 determined 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) Polyethylene glycol content
The content of polyethylene glycol was measured by ¹ H-NMR method.
The measuring apparatus and conditions were as follows.
Measuring device: JEOL Ltd .; JNM-LA400
Solvent: HFIP-d ₂ / CDCL ₃ (5/5)
Sample concentration: 5.0 wt / vol%
Measurement temperature: 25 ° C
Chemical shift criteria: Tetramethylsilane (TMS) was 0 ppm.
Number of integrations: 256 times Waiting time: 2.9 seconds A ¹ H-NMR spectrum of each measurement sample was measured using a fiber washed for 24 hours at room temperature as a sample. To separate the titanium oxide, the lysate was centrifuged and the supernatant was measured.
The content rate was calculated | required using the methylene group signal of polyethyleneglycol.
The measurement was performed 3 times for each sample, and the average value was obtained.

(4) Water absorption The fabric was attached to a round frame for embroidery having 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 surface of the fabric. The wet and diffuse water absorption 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 was repeated 100 times with a commercially available fully automatic washing machine with 1 g / 10 liter of detergent and a bath ratio of 1: 1000, and then the same water absorption and diffusion area was measured.
According to this measurement, if the water absorption diffusion area is 10 cm ² or more, the water absorption is good.

(5) Quick-drying The fabric (10 cm square) was sufficiently wetted with water and dehydrated with a dehydrator at 2000 rpm for 1 minute, and then the weight of the fabric was measured to calculate the water content. 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.
(6) 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 4 or higher, it has good dyeing fastness.

(7) Fibril resistance The dyed product was evaluated according to JIS-L-1096 method. 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.
(8) Strength Measured based on JIS-L-1013.
(9) Spinning Stability One day of melt compound spinning-continuous drawing was carried out for each example using a melt compound spinning-continuous drawing 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
○: Less than 2 yarn breaks, fluff generation package ratio less than 10% ×; Three or more yarn breaks, fluff generation package ratio 10% or more

[Examples 1-4, Comparative Examples 1-2]
Polyethylene glycol having a number average molecular weight of 20,000 with respect to polyethylene terephthalate B containing 2.0% by weight of titanium oxide on the sheath side and having an intrinsic viscosity [η] of 0.62 (measured in orthochlorophenol at 1% by weight) As shown in Table 1, a polymer obtained by blending polyester A having 4% by weight with different mixing ratios in the sheath component is used, polyethylene terephthalate B is used on the core side, and a twin screw extruder is used. And extruded from a nozzle having 36 spinning holes perforated in a W-shape and having a sheath core weight ratio of 25/75 at a spinning temperature (spinhead temperature) of 292 ° C. and a spinning speed of 2000 m / min. The filament was heated with a first draw roll at ℃, heat set with a second draw roll at 130 ℃, drawn, and the single yarn cross-sectional shape was 84 deci To obtain a drawn yarn of the box / 36 filaments. The obtained fiber had a recess opening angle of 130 degrees in the W cross section, a flatness of 3.5, and the fiber elongation was 34 to 36%.

The obtained polyester composite fiber was false twisted with a two-heater false twister by a conventional method to obtain false twisted yarn.
From the obtained false twisted yarn, a smooth knitted fabric was prepared with 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, the treatment time is adjusted so that the alkali weight loss rate is 10% by weight under the following conditions, and the weight is reduced with a liquid dyeing machine. Processing was performed.
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, the product 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 (manufactured by Dystar) 2.2% omf
Auxiliary agent: Nikka Sun Salt RM-340 (manufactured by Nikka Chemical Co., Ltd.) 0.5 g / liter Acetic acid: 0.5 cc / liter Sodium acetate: 1 g / liter Bath ratio: 1:25
Dyeing temperature and time: 130 ° C, 30 minutes

After the 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., the following chemicals are added thereto to adjust a reducing washing bath having the following concentration, and 80 Reduction cleaning was performed at 20 ° C. for 20 minutes.
Hydrosulfite 2 g / liter Caustic soda-2 g / liter Bisnole UP-10 (manufactured by Yushi Kogyo 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 0.3 to 0.5 μm and a length of 3 μm or more were formed in the fiber axis direction on the surface of the polyester composite fiber. Many streak-like grooves having a width of 0.3 to 0.6 μm were observed in the recesses of the W cross section.

[Examples 5 to 8, Comparative Examples 3 and 4]
In this example, the effect of the blending ratio of the sheath component and the core component of the sheath-core polyester composite fiber will be described.
In the same manner as in Examples 1 to 4, the ratio of the sheath component to the core component was varied as shown in Table 2 at a blend ratio of 30 wt% of polyester A.
Table 2 shows the evaluation results of the water-absorbing diffusion area, dehydration drying property, dyeing fastness, and fibril resistance of the dyed fabric.
[Examples 9 to 13, Comparative Examples 5 and 6]
In this example, the effect of the alkali weight loss rate will be described.
In the same manner as in Examples 1 to 4, fabrics were obtained with a blend ratio of polyester A of 30 wt% and a sheath core ratio of 30/70, with different alkali weight loss rates as shown in Table 3.
Table 3 shows the evaluation results of the water-absorbing diffusivity, dehydration drying property, dyeing fastness, and fibril resistance of the dyed fabric.

  The polyester conjugate fiber of the present invention is useful for sports and inner knitted fabrics when used in knitted fabrics.

It is a schematic diagram which shows the single yarn of the sheath-core type polyester composite fiber of this invention.

Claims (4)

A polyester composite fiber, which is a sheath-core polyester composite fiber, having groove-like micropores parallel to the fiber axis direction on the surface of the fiber and satisfying the following requirements (1) to (3) fiber.
(1) The fiber specific surface area formed by the micropores is the fiber specific surface area S1 (cm ² / g) calculated from the cross-sectional shape of the single yarn by optical microscope observation, and the fiber specific surface area measured by the BET method. The S2 (cm ² / g) ratio (S2 / S1) is 1.5 to 5.0,
(2) The cross-sectional shape of the single yarn is a W cross-section, the flatness of the single yarn is 2 to 5, and has a groove of a fine hole continuous along the fiber length in at least one concave portion of the cross-section.
(3) The content of polyethylene glycol contained in the fiber is 0.05 to 2.0% by weight.   The ratio of fiber specific surface area S1 and fiber specific surface area S2 (S2 / S1) is 2.0-4.5, The polyester composite fiber of Claim 1 characterized by the above-mentioned.   A method for producing a sheath-core type polyester composite fiber, wherein the core component is made of polyester B, and the sheath component is copolymerized with 2 to 10% by weight of polyethylene glycol having a number average molecular weight of 4,000 to 50,000, and polyester B An alkaline aqueous solution containing alkylbenzyldimethylammonium chloride, comprising a polyester component having a mixing ratio of 10 to 50% by weight in the sheath portion of polyester A, melt-spun and then subjected to drawing heat treatment and fiberizing 3. The method for producing a polyester composite fiber according to claim 1, wherein an alkali weight loss treatment is performed at a temperature of 100 ° C. or less so that the weight loss rate is 4 to 35 wt%.   The method for producing a polyester composite fiber according to claim 3, wherein the blending ratio of the sheath component and the core component is 10/90 to 50/50.

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