JPH0726248B2 - Method for producing polyester staple fiber - Google Patents

Description

TECHNICAL FIELD The present invention relates to a method for producing a polyester staple fiber having a special cross-sectional shape, and more specifically, it uses a π-shaped discharge nozzle and has good spinnability. In addition, the present invention relates to a method for producing a fine fiber staple fiber having excellent pill resistance and water absorbency.

[Prior art]

Heretofore, there has been known a method of using a low-viscosity polymer to reduce the strength of the fiber in order to obtain a fiber having good pill resistance, or using a polymer obtained by copolymerizing a third component effective to reduce the strength. There is. Further, for example, JP-A-51-109320,
As disclosed in Japanese Patent Application Laid-Open No. 52-148221, the cross section of the fiber has a U-shape or the like to improve the pill resistance.

On the other hand, in order to obtain a fiber having good water absorption, a polymer obtained by copolymerizing a third component effective for water absorption is used, a water absorbing agent is applied to the fiber surface, or a microvoid is formed on the fiber surface. Methods of hollowing fibers and combining them are known. Furthermore, for example, JP-A-55-1220
As disclosed in Japanese Patent Publication No. 74, the water absorption is attempted to be improved by making the fiber cross section irregular.

[Problems to be solved by the invention]

However, it is difficult to impart practically sufficient anti-pill property and water absorption by any of the above-mentioned methods. This is because, when it is attempted to impart functionality to fibers in this manner, various problems such as reduction in fiber strength, occurrence of frosting, and reduction in dyeability occur, and product costs have increased. Therefore, as a result of intensive investigations by the present inventors, the fiber cross section has a special shape, that is, a π type, to minimize the cost increase of the product and to maintain the basic properties of the fiber. It was found that a fiber satisfying not only anti-pill property but also water absorbency can be obtained at the same time. However, while the π-type cross-section yarn has such excellent properties, when it is spun using a spinneret with a large number of holes from the viewpoint of improving productivity, fusion, yarn breakage, and yarn thickness irregularity (fineness irregularity) Such problems will occur.

The object of the present invention is to solve these problems, and the nozzle shape is
An anti-pill that is excellent for clothing fabrics by using a letter-shaped multi-hole staple for staples and spinning fibers with fineness suitable for clothing fabrics without any problem in spinnability (thread breakage, fusion, yarn unevenness) To provide a method for producing a staple fiber having properties and water absorbency.

[Means for solving problems]

The above-mentioned object of the present invention is composed of linear cross-sections A, B, and C made of polyester in which 85 mol% or more of the structural unit is ethylene terephthalate, and two other straight lines are provided for the linear cross-section A. -Shaped cross-sections B and C are joined to the same side surface of the part that enters inside from the tip of the straight-line cross-section A, and the outer surfaces of the straight-line cross-sections B and C are straight to the tip of the straight-line cross-section A. When manufacturing a polyester fiber having a special fiber cross section having a special cross-sectional shape of 2.5 denier or less inside the tangent line formed by the outer surfaces of the cross-sections B and C, (i) a π-type nozzle hole satisfying the following formula is used. 0.05 ≤ S ≤ 0.08 (mm) 0.5 ≤ l ₂ / l ₁ ≤ 1.2 W ≥ 0.20 (mm) h ≥ 0.30 (mm) Z ≥ 0.10 (mm) 75 ° ≤ α ≤ 100 ° (However, S: Slit width, l ₁ : Slit length, l ₂ : Slit height, W: Groove width, h: Groove depth, Z: Join position, α : Slit angle) (b) Draft rate ≦ 500, discharge amount per hole circumference ≧ 0.015
(C) The polymer is discharged at (cm ³ / sec ・ cm), and (c) the chimney cooling start position is 30 to 100 mm below the die surface, and the chimney cooling length is 200 mm or more. This can be achieved by a method for producing polyester staple fiber, which is characterized by cooling at a wind speed of ~ 90 m / min.

The cross section of the staple fiber aimed at in the present invention is a π type cross section as shown in FIG. 1, and the spinneret to be used preferably has a nozzle hole having a cross section as shown in FIG. 2, for example. It is more preferable to make the tips of the slits b and c circular as shown in FIG. Conventionally known irregular holes T, Ж, H, U
In terms of form, the excellent anti-pill property and water absorbency aimed at by the present invention cannot be simultaneously satisfied. Further, the spinneret of the present invention has staple productivity, and naturally, a multi-hole type is required from the viewpoint of productivity, and it is preferable to use a 300-hole type or more. The hole size of the die used in the present invention must satisfy the following range.

0.05 ≤ S ≤ 0.08 (mm) 1.5 ≤ l2 / l1 ≤ 1.2 W ≥ 0.20 (mm) h ≥ 0.30 (mm) Z ≥ 0.10 (mm) 75 ° ≤ α ≤ 100 ° For the hole size of the die, use Fig. 2 Will be further explained.
In the present invention, the slit widths S ₁ , S ₂ and S ₃ are all
It must be in the range of 0.05 to 0.08 (mm). If it is narrower than 0.05 mm, nozzle clogging tends to occur due to foreign substances and decomposed substances in the polymer. On the other hand, when it is larger than 0.08 mm, the draft ratio is increased, which causes an increase in yarn unevenness and yarn breakage. Considering the accuracy in manufacturing the base, it is preferable
It is preferably 0.06 to 0.08 mm, and S ₁ , S ₂ , and S ₃ are all the same.

Slit height and the ratio l ₂ / l ₁ of the slit length must be in the range of 0.5 to 1.2, preferably 0.6 to 1.0. l ₂ / l
_{When 1} exceeds the range of the present invention, a staple fiber having the cross-sectional shape intended by the present invention cannot be obtained. l2 / l1
When it is less than 0.5, the fiber cross-section of the obtained fiber becomes substantially circular and the water absorbing effect is lost. l ₂ / l
_{When 1} is larger than 1.2, the risk of hollowing during spinning becomes large, which causes yarn breakage.

The groove width W and the groove depth h must be 0.20 mm and 0.30 mm or more, respectively. The preferable groove width W is 0.2 to 1.0 mm, and the groove depth is 0.3 to 1.0 mm, more preferably 0.2 to 0.8 mm and 0.3 to 0.7 mm, respectively. Groove width W is 0.20
If it is less than mm, fusion is likely to occur when the polymer is discharged from the slits b and c. Further, by setting the groove depth h formed by the slits b and c to be 0.3 mm or more, the target groove depth of the fiber cross section can be stably obtained even when the spinning conditions, particularly the temperature, are changed.

Also, the joining position of the slits b and c with respect to the slit a
It is necessary that Z ₁ and Z ₂ are joined to the inside of the tip of the slit a by 0.1 mm or more, and preferably in the range of 0.1 to 0.25 mm. When it is smaller than 0.1 mm, it becomes difficult to obtain the staple fiber having the cross-sectional shape of the present invention, which is joined to the inside of the tip portion due to the dispersion effect at the time of ejection.

Next, the slit angle α formed by joining the slits b and c to the slit a may be set in the range of 75 ° to 100 °, but is set to 90 ° C from the viewpoint of stability of the discharge polymer. Is most preferred. If α exceeds 100 °, the staple fibers will be hollowed out and the water absorption will decrease. On the other hand, if it is smaller than 75, the cross section becomes close to a flat cross section, and the water absorption is reduced. The die of the present invention is not limited to the shapes shown in FIGS. 2 and 3 as long as it satisfies the above nozzle hole size, but it can be used.
It is more preferable to use a spinneret having a nozzle hole having a circular hole shape with a shear stress in the range of to 150 (× 10 ⁵ dyne / cm ² ) in order to reduce the fineness unevenness of the spun yarn.

As the conditions for spinning using a spinneret having the above-mentioned nozzle holes, it is possible to adopt the conditions usually employed, but the staple fiber obtained by the present invention is a clothing that can exhibit excellent anti-pill property and water absorption. Since it is used in the field of application, its fineness should be 2.5 denier or less, and the discharge conditions should be such that it has the set fineness. Also, in order to reduce yarn breakage and yarn unevenness during spinning, the nozzle hole The discharge rate per circumference should be 0.015 (cm ³ / sec · cm) or more, preferably 0.015 ≦ discharge quantity per hole circumference ≦ 0.0375, more preferably 0.015 ≦ discharge per hole circumference Amount ≤0.0
30. Further, the draft ratio needs to be 500 or less from the viewpoint of fineness and shear stress in the hole, and is preferably 100 to 500.

The spinning temperature is preferably 30 ° C. or more higher than the softening point of the polymer. The spun yarn is cooled using an annular outer blow chimney. What is a ring-shaped outer chimney?
This is a chimney in which the cooling air rectified from the outer peripheral portion of the yarn as shown in FIGS. In the case of cooling the π-shaped cross section in the present invention, it is particularly necessary to cool the whole uniformly, and in order to suppress the occurrence of spots as much as possible, the yarn must be cooled without shaking as much as possible. For that purpose, an annular outer blowing chimney that can be cooled from the outer peripheral portion of the yarn is required. The blowing of the cooling air starts from the position of 30 to 100 mm below the mouth surface,
Moreover, it is necessary to spray from the periphery of the outer surface of the yarn within a range of 200 mm or more below that. It is preferable to start cooling from 35 to 80 mm below the surface of the die and spray in a range of 200 to 1000 mm. If cooling is started at a position within 30 mm below the surface of the spinneret, the spinneret is also cooled, which causes deterioration of spinnability. Further, when the cooling start position exceeds 100 mm below the die surface, the effect of uniform cooling becomes insufficient. Cooling needs to be performed at a wind speed of 30 to 90 m / min, preferably 30 to 70 m / min. If it is performed at less than 30 m / min, the yarn will not be sufficiently cooled and fusion will easily occur.
If the value exceeds min, the yarn will be greatly shaken, and the cause of fineness unevenness and yarn breakage will easily occur. As for the cooling direction with respect to the yarn cross section, it is preferable to perform the cooling from the tip direction of the slits b and c toward the slit a in order to stabilize spinning.

The undrawn yarn obtained by the above-mentioned method is made into a staple fiber through drawing, crimping, heat setting and cutting steps. The conditions of the stretching, crimping, heat setting, and cutting steps may be those normally adopted, but from the viewpoint of improving spinnability, for crimping, the toe temperature is steamed before crimping. It is preferable that the temperature is 70 ° C. or higher, and the crimp degree is improved by heat treatment in a crimper at 90 ° C. or higher for 0.5 seconds or longer. Steam treatment is particularly preferable as the heat treatment in the crimper. The π cross-section yarn of the present invention has water absorbability by itself, but it is preferable to perform alkali treatment in the range of 5 to 25% in order to further improve water absorbency.

The polyester in the present invention is 85% by mole or more of the constitutional unit is ethylene terephthalate, and conventionally known carboxylic acids such as isophthalic acid, adipic acid, azelaic acid and trimellitic acid, and derivatives thereof, diethylene glycol, polyethylene glycol or other 15 mol% based on the total amount of one or more copolymerization components
It may be included in a range not exceeding. In addition, the intrinsic viscosity of the polyester obtained in ortho-chlorophenol at 25 ° C is 0 in order to maintain a sharp π cross-sectional shape during spinning.
6 or more is desirable.

[Examples] The present invention will be specifically described with reference to Examples. The fineness variation rate, anti-pill property, water absorption height, and anti-frosting property were determined by the following methods.

A. Fineness Fluctuation Rate Using a DENIER COMPUTER DC-11B (Search Control Electric Co., Ltd.), 40 single fibers were measured under the conditions of a sample length of 25 mm and an initial load of 0.1 g / d.

B. Anti-pill ICI method It was judged by 5 hours.

C. Water absorption height The bottom end of a strip sample having a length of 20 cm and a width of 1 cm was immersed in water by the Bayrec method, and the water absorption height after 10 minutes was measured.

D. Anti-frosting property Using an appearance retention tester, two sample pieces were brought into contact with each other in a circular shape with a diameter of 3 cm under a load of 750 g and rubbed with each other for 10 minutes. The grade was judged.

Example 1 Intrinsic viscosity measured in 25 ° C. orthochlorophenol solution
0.66 polyethylene terephthalate was spun under the following conditions using a 170 mmφ spinneret with an inner diameter of 120 mmφ and an outermost diameter of 146 mmφ with 500 nozzle holes annularly arranged and having the hole size shown in Table 1. Was done.

Temperature 300 ℃ Discharge rate 282g / min Spinning speed 1100m / min Chimney Annular external blow-out chimney Cooling start position 60mm below the spinneret surface Cooling wind speed 50m / min Cooling length 600mm The spinning condition and the fineness variation rate of the obtained undrawn yarn are combined. 1
Shown in the table.

Further, the undrawn yarns obtained in Experiment Nos. 2 and 5 were made into tow of 500,000 denier. Then, the film was stretched 3.3 times in a 95 ° C liquid bath, and subsequently subjected to a fixed length heat treatment for 8 seconds on a 200 ° C hot plate,
The tow temperature was adjusted to 72 ° C by steaming, and crimping was applied while steaming at 92 ° C in a crimper. 95
After drying at ℃, it was cut into 38 mm to make staple fiber. Experiment No. 2 staple fiber (Example) has a fineness of 1.5 d, strength of 5.7 g / d, elongation of 35%, toughness of 200, and Experiment No. 5 staple fiber (comparative example) has a fineness of 1.5d, strength 5.0g / d, elongation 36%, toughness 180
Met. Using each of the obtained staple fibers, for comparison, a polyester staple fiber having a circular cross section with a cut length of 38 mm and a denier of 1.5 mm, and cotton were subjected to ordinary spinning to obtain a spun yarn of 30S as a cotton count. An interlock knit was produced using this yarn.
Continue to use scouring, dyeing,
A finishing set was carried out. Interlock knits other than cotton were subjected to alkali treatment after scouring to reduce the amount by 15%, and then dyed and finish-set samples were also prepared. The properties of the obtained knitted fabric are shown in Table 2.

As is clear from Tables 1 and 2, according to the method of the present invention, good spinnability, small fineness unevenness of undrawn yarn, water absorption,
It can be seen that a polyester staple fiber excellent in pill resistance and frosting resistance can be obtained.

Example 2 As shown in Table 3, spinning was performed in the same manner as in Example 1 and Experiment No. 2 except that the cooling conditions were changed.

The results are also shown in Table 3.

From Table 3, even if the hole size of the die is within the range of the present invention, if the cooling conditions are not proper, yarn breakage, fusion, fineness unevenness occur, and the sharpness of the cross section in the present invention cannot be maintained. I understand.

〔The invention's effect〕

According to the method of the present invention, a fiber having a π cross-section with a special shape can be obtained without problems in manufacturing such as spinnability, and when the obtained staple fiber is used as a cloth for clothing, it has excellent anti-pill and water absorption properties. Is to demonstrate.

[Brief description of drawings]

FIG. 1 is an example of a cross-sectional view of a yarn obtained by the present invention. 2 and 3 show examples of nozzle holes used in the present invention. FIG. 4 is a side view of an example of the annular outer blow-out chimney used in the present invention, and FIG. 5 is a sectional view taken along the line M-N thereof. 1. Clasp 2. Thread 3. Ring outer tube chimney 4. Cooling air

Claims (1)

[Claims] 1. A linear cross section A made of polyester in which 85 mol% or more of the constituent units is ethylene terephthalate.
B and C, two other linear cross-sections B and C with respect to the linear cross-section A are joined to the same side surface of the straight-line cross-section A from the tip to the inside, and The single fiber fineness is 2.5 denier or less having a special cross-sectional shape in which the outer surface of each of the cross-sections B and C is inside the tangent line formed by the tip of the straight cross-section A and the outer surface of each of the straight cross-sections B and C. (B) Using a die having a π-type nozzle hole that satisfies the following formula, in producing Pollistel staple fiber: 0.05 ≦ S ≦ 0.08 (mm) 0.5 ≦ l ₂ / l ₁ ≦ 1.2 W ≧ 0.20 (mm) h ≧ 0.30 (mm) Z ≧ 0.10 (mm) 75 ° ≦ α ≦ 100 ° (However, S: slit width, l ₁ : slit length, l ₂ : slit height, W: groove width, h: groove depth , Z: Joining position, α: Slit angle) (b) Draft rate ≤500, Discharge rate per hole circumference ≥0.015
(C) The polymer is discharged at (cm ³ / sec ・ cm), and (c) the chimney cooling start position is 30 to 100 mm below the die surface, and the chimney cooling length is 200 mm or more. A method for producing polyester staple fiber, which comprises cooling at a wind speed of 30 to 90 m / min.