JPS6297917A - Production of polyester fiber - Google Patents

Abstract

PURPOSE:To stably obtain bright polyester multifilament yarns of triangular cross section having a small fiber fineness, by extruding a molten polymer through a spinneret having specific extrusion holes. CONSTITUTION:A polyester is melt molded through extrusion holes having three leg parts (L), (M) and (N) radially extending from the center (O) at 120 deg. included angle, constant slit width (rmm) leading from points (L1), (M1) and (N1) to points (L2), (M2) and (N2) and semicircular tips having a diameter (rmm) of the leg parts. Each concave circular arc held between the adjacent leg parts constitutes part of a circumference of a circle having a radius (Rmm) with the center at (O1), (O2) or (O3) and straight lines (O1M1O2), (O2N1O3) and (O3L1O2) have respectively an equal length to form an equilateral triangle. The ratio (R/r) is 1.5-5.0 and the ratio (r/l) is 0.35-7 (l=l2-l1).

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to a method for stably producing a polyester multifilament having a irregular cross section and a small single fiber fineness suitable for use in clothing.

[Conventional technology]

B△50D/36F, B△75 D/48F.

B△75D/72F (here, B indicates that the gloss is bright with a very small amount of matting agent, △ indicates that the cross section of the cross-section is triangular, and D and F indicate the fineness of the multifilament ( Polyester multifilament with a modified cross section with a single fiber fineness of 2.0 denier or less is prized as a silky material, and especially has two groups of multifilaments: high shrinkage and low shrinkage. The differential shrinkage blend obtained by blending fibers is a yarn (for example, a mixed yarn of high shrinkage B△37.5D/24F and low shrinkage B37.5D/24F) or a single fiber fineness of about 1 denier. Super multi extra fine filament B
75D/72F is a material with a texture and luster that even surpasses that of silk, and is highly rated. However, as is well known, such bright, irregularly shaped, and small filament fineness varieties are difficult to spin and spin in actual industrial production.
This method has problems in that single fiber breakage and yarn breakage are likely to occur during the drawing process, reducing operability and resulting in poor yield, which is economically disadvantageous. Due to the fuzz and loops inherent in the fabric, it reduces the machine operating rate during the warping or shedding process, and it also has a quality origin that causes defects (scratches) on the fabric during knitting and weaving. The spinning speed is increased to 1 as a means to solve more problems than ever before.
A method of lowering the spinning speed to below 200°C has been adopted, but although it is true that lowering the spinning speed is extremely effective,
In the case of producing products with a certain number of fibers and filaments, there is a nearly linear relationship between the spinning speed and the amount of molten polymer discharged up to 3000 m7 minutes, and a decrease in the spinning speed immediately reduces productivity. This means a decrease in the cost, which ultimately leads to an increase in costs and creates a new problem of being economically disadvantageous.

[Problem that the invention seeks to solve]

As described above, the purpose of the present invention is to reduce the fineness of single fibers in prite, which is difficult to stably produce due to frequent occurrence of single fiber breakage and yarn breakage during spinning and drawing processes at spinning speeds exceeding <1200 m/min. It is an object of the present invention to provide a method for producing polyester multifilaments having a small irregular cross section in an extremely stable manner by specifying the shape of a front plate which is preferably disposed behind the spinneret over the entire history of the spinneret.

[Means for solving problems]

The gist of the present invention is that the composition of the matting agent is Q, l.
When manufacturing a polyester fiber composed of a multifilament consisting of a polyester polymer having a weight of % or less, a fiber cross section of which is substantially an equilateral triangle, and a single fiber fineness of 2.0 denier or less, the polyester fiber extends radially from the center. It is formed from three legs, each leg has a part where the slit width gradually decreases toward the tip, followed by a part where the slit width is constant, and a semicircle is arranged at the tip, The molten polymer is spun using a spinneret having a discharge hole in which each of the concave portions narrowed in the adjacent foot portions forms an arc;
The present invention provides a method for producing polyester fibers, characterized in that the fibers are drawn at a speed of 200 m/min or more.

The present invention will be explained in detail below.

In the present invention, a substantially equilateral triangular fiber cross section specifically refers to the shape shown in FIG. d is 0.
It refers to something with a rounded curvature of less than 0.06 mm. If d exceeds 0.06 mm, the cross section of the fiber will be more circular than an equilateral triangle, and the silk-like luster characteristic of a triangular cross section will be lost, which is not preferable. The above-mentioned substantially equilateral triangular fiber cross section can be easily obtained by spinning a °C melt polymer using a spinneret having a discharge hole of the shape illustrated in FIG.

In FIG. 2, the discharge hole is composed of three legs, M and N, which extend radially at an included angle of 120° C. while gradually decreasing the slit width even when the center is 0.

Each foot is located at a point L1 located l@mN away from the center O. M,,N,
The slit width is constant (rmm) from the point 112mx away from the center 0, ,M,,N, and at the tip of the foot, centering on one point Lt s Mt , N1, the diameter is γ. A certain semicircle is placed. The concave arc narrowed by the adjacent foot portions constitutes a part of the circumference of a circle centered at OI I OI T o and has a radius of only Rmll, and the straight line 0. M,
O.

02NI03. O8L, 0. are equilateral triangles of equal length 0.0.0. form. To obtain an equilateral triangular fiber cross section, R and 7 and r and l (where ""l!
-11) is extremely important, R/y is 1.5
~5.0 and y/73 must be in the range 0.35-7.

In the present invention, the depth H of the discharge hole (1) in FIG. of/
It is preferable to make it as shallow as possible in order to suppress the abrasion stress of the molten polymer on the discharge hole wall, but in reality it is 0.3
It is extremely difficult to make it lower than a dragon.

In the present invention, the area of the °C discharge hole is extremely important in reducing the spinning draft. The spinning draft ratio is given by the following formula (1
1, but must be in the range of 80-200.

V: Spinning speed Cm 1 min) A: Single hole area of the spinneret (P: Melt 1 coalescence density (//cm") Q: Discharge amount per single hole (//min) When the spinning draft exceeds 200, the molten polymer Due to the rapid increase in tensile stress resulting from excessive elongation deformation of the yarn, the fineness unevenness of the yarn becomes thick (this results in single fiber breakage or a decrease in strength and elongation).

If the spinning draft is less than 80, the spinning tension will be extremely low and a kneading (bending) phenomenon will occur at the discharge hole, resulting in single fiber breakage.In addition, the friction stress of the molten polymer on the wall of the discharge hole will be excessive, causing the polymer to be discharged. The flow behavior becomes non-uniform on the hole exit side, resulting in a decrease in fiber strength and elongation, or
) The effect becomes so pronounced that the cross section of the resulting fiber becomes roundish. This increase in the friction stress of the molten aggregate on the wall of the discharge hole is inevitably accompanied when the area of the discharge hole is reduced in an attempt to lower the spinning draft.

In addition, reducing the surface a of the irregularly shaped discharge hole actually has problems with machining accuracy, and unnecessarily reducing the surface a causes variations in the area and causes asymmetry in the fineness between single 11 fibers, which is not desirable. .

From the above spinning draft and practical machining accuracy, in the present invention, the discharge hole area is 0.025 to 0,070 mm.
” must be within the range.

In the present invention, the degree of irregularity l of the discharge hole defined by the following formula (2) is also important.

For example, the degree of irregularity is 12.6 for a perfect circle, 16 for a square,
20.8 for an equilateral triangle, which is an index of irregularity that increases as the degree of irregularity increases, and although it varies depending on the shape of the discharge hole, when it exceeds a certain value, the abrasion stress of the molten polymer on the wall of the discharge hole increases. The flow becomes unstable, for example, vibrations occur and spinning becomes unstable.

In the discharge hole shape used in the present invention illustrated in FIG.
The above equation (2) can be rewritten as follows.

In the present invention, it is necessary that the temperature and degree of irregularity I are 35 or less. If it exceeds 35, 1" of bath melting on the discharge hole wall.
The stress becomes excessive and single fiber breakage tends to occur at spinning speeds of 1200 m/min or more.

In the present invention, the process shown in Fig. 4 A) is carried out behind the discharge hole of the spinneret.
(If a front plate (2) with circular aperture holes is provided, it is possible to further prevent single fiber breakage and yarn breakage during the spinning and drawing processes and improve manufacturing stability. The throttle hole (2) is also formed in the inlet part (3) and throttle part (4) of the bath melting body, and the discharge hole (5) following these, but for the purpose of suppressing the flow of the molten polymer. It is also preferable to use a front and (2) having a restricting hole as shown in FIG. 4(b).

It is sufficient if the discharge hole of the throttle hole in the front plate is circular.

In the present invention, the area of the discharge hole of the throttle hole in the front plate is required to be 0.8 to 1.2 times the area of the discharge hole of the spinneret. By applying high back pressure to the discharge holes of the spinneret to exceed 1.2 times of If the gel contained in the coalescence is elongated into stripes, the Li gel will not be sufficiently effective in suppressing single fiber breakage during spinning and drawing. In addition, if it is less than 0.8, both the area of the discharge hole of the spinneret and the area of the discharge hole of the front plate will be reduced by 7 mm, and the back pressure will become extremely high. Problems arise, such as the need to modify the structure.

As described above, in the present invention, the front plate and the spinneret are used in combination, and the molten polymer is squeezed in two stages, so that the polymer chains are preliminarily arranged in the direction of the fiber technician using the front plate. (The friction stress of the molten polymer at the squeezing part contributes), the gel was lengthened into stripes, the internal stress of the molten polymer was made uniform, and then it was discharged from a spinneret discharge hole with an irregular cross section. ), the flow of the molten polymer becomes extremely stable, reducing single fiber breakage, yarn breakage, etc.

The polyester polymer in the present invention refers to polyethylene terephthalate in which 85 mol% or more is composed of repeating units of ethylene terephthalate, but it is copolymerized with other dicarboxylic acid components and/or diol components in a range of less than 15 mol%. There is no problem with including it as an ingredient.

Such modified polyesters include, for example, a polyester prepared by combining 1 to 5 mol% of C5-sodium-sulfoisophthalic acid as a dicarboxylic acid component, 1 to 5 mol% of 5-sodium-sulfoisophthalic acid, and adipine. Examples include polyesters copolymerized with 1 to 10 mol% of acid, but are not limited to these.Polyesters containing 5-sodium-sulfoisophthalic acid as a copolymer component and ℃ are well known. As described above, the flow viscosity at the time of melting is high due to the intermolecular or intramolecular hydrogen bonding force. Particularly effective results have been observed.

The present invention preferably uses a matting agent such as titanium oxide with a content of 0.1
The target is polyester polymers with a blending ratio of wt% or less. If it exceeds 0.1 wt%, the fiber loses its transparency (brightness) and silk-like luster.

However, as long as the transparency (brightness) is not lost, an inorganic material having a refractive index similar to that of the polyester polymer may be blended as a lubricant. Examples of such inorganic substances include calcined kaolin and uncalcined kaolin, but are not limited thereto. Calcined or uncalcined kaolin is used as a lubricant (if used, 0.1 to 2 Owt% is added to the polyester polymer).
It is sufficient to mix them together. Since these kaolins have a thickening effect, they increase the flow viscosity of the molten polymer by blending them, but as described above, the method for producing polyester fibers of the present invention involves spinning a polymer that has a high flow viscosity when melted. There are young and old.

〔Example〕

The present invention will be explained below with reference to Examples.

Examples and Comparative Examples Polyethylene terephthalate containing calcined kaolin O1i wt% with a relative viscosity (metacresol, 25° C.) of 1.63 and consisting only of ethylene terephthalate units substantially free of matting agents was bath-melted, The yarn was spun at 22,547/min at 290°C from a spinneret equipped with 36 discharge holes of the shape shown in Table 1, and after cooling the yarn according to a conventional method and applying an oil agent, It was picked up in 1 minute. At this time, the diameter of the discharge hole on the front plate is 0.15° 0.25
and 0.35 m x φ circular shapes were used in combination.

The polyethylene terephthalate undrawn fiber thus obtained was fed to a normal roller/grate type drawing and twisting machine, and the K was 2.76 under the conditions of rollers at 85°C and grate at 145°C.
Double K A'! ' It was stretched and wound onto a pirn at 800 m/min.

The results are shown in Table 2.

In Table 1, spinning and drawing stability indicate the total number of single fiber breaks and yarn breaks that occurred during the production of 1 ton of product.

〔Effect of the invention〕

According to the present invention, polyester multifilamen (f, ff) fibers, which are bright and have an extremely high commercial value and have an equilateral triangular cross section with a single fiber fineness of 2.0 denier or less, are spun at a speed of 1200 m/min or more. It is possible to manufacture it rapidly and stably, and thereby it is possible to greatly reduce the myYI cost.

[Brief explanation of drawings]

FIG. 1 is a cross-sectional view of a substantially equilateral triangular fiber of the present invention, FIG. 2 is a cross-sectional view of an example of a non-inventive spinneret discharge hole, and FIG. 3 is a longitudinal cross-section of a spinneret of the present invention. Figure, Figure 4a),
(B) is a longitudinal sectional view of an example in which the front plate and spinneret of the present invention are assembled. DESCRIPTION OF SYMBOLS 1... Spinneret discharge hole, 2... Front plate, 3... Molten polymer introduction part, 4... Squeezing part, 5... Front plate discharge hole 1 Figure 2 Figure 3 (b) Part 4 (b)

Claims (3)

[Claims] (1) A polyester made of a polyester polymer containing 0.1 wt% or less of a dissipating agent, a multifilament having a substantially equilateral triangular fiber cross section and a single fiber fineness of 2.0 denier or less. When manufacturing the fiber, it is formed from three legs extending radially from the center, each leg has a part where the slit width gradually decreases toward the tip, followed by a part where the slit width is constant, and the slit width is constant. The molten polymer was spun using a spinneret having a semicircular shape and a discharge hole in which each of the recesses narrowed between adjacent legs formed an arc, and the molten polymer was spun at a speed of 1200 m/min or more. A method for producing polyester fiber characterized by taking it off at a high speed. (2) The discharge hole of the spinneret is 0.025 to 0.070 mm
Hole area A of ^2 and irregularity l of 35 or less (defined in text)
2. The method according to claim 1, using a spinneret having: (3) Behind the discharge hole of the spinneret, 0 of the discharge hole area A
．． 3. The method according to claim 2, which uses a spinneret provided with a front plate provided with circular discharge holes having an area of 8 to 1.2 times.