JP2636879B2 - Polyester fiber - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a polyester fiber. More specifically,
The present invention relates to a polyester fiber produced by a high-speed spinning take-off method and having excellent pill resistance and heat stability.

[Problems to be solved by conventional technology and invention]

When a polyester fiber is used for a knitted fabric, there are advantages such as excellent wrinkle resistance and durability, easy handling, and easy drying. However, on the other hand, the fibers are pulled out of the tissue due to friction while wearing, and the fibers are entangled with each other to produce pills. Especially for high strength fiber such as polyester fiber,
The resulting pill has a drawback that it is difficult for the pill to fall off, but rather grows and makes the surface of the knitted fabric difficult to see.

In recent years, there has been a strong demand for improved productivity in the production of polyester fibers.
High speed spinning take-off methods using high take-off speeds in excess of m / min have been attempted.

For this purpose, there has been proposed a method for producing a fiber which suppresses the generation of pills, which is a drawback of the polyester fiber, by a high-speed spinning test take-off method. For example, in Japanese Patent Application Laid-Open No. 54-30923, a special pressurized gas chamber is provided under the spinneret, and fibers spun from the chamber and pressurized air are ejected together to achieve a spinning speed of 6000 to 8000 m / m. In addition, it is intended to obtain an anti-pill fiber. In such technology, special equipment must be provided under the spout,
It is disadvantageous in terms of operation and equipment costs. Moreover, in the method in which both the pressurized air and the fiber are jetted out as described in the above-mentioned publication, denier spots and stain spots occur due to slight fluctuations in the air pressure, and practical fibers cannot be obtained. Moreover, the anti-pill property of the obtained fiber is also insufficient.

JP-A-57-133216 discloses a technique for obtaining an anti-pill fiber by increasing the water content of a polyester chip and spinning the yarn at a speed of 6000 m / min or more. However, the fiber obtained by increasing the moisture content of the chip is liable to cause staining spots, and it is necessary to keep the moisture content low as in the case of ordinary polyester spinning in order to eliminate the disadvantages.
As a result, there is a problem that the strength is increased and the anti-pill property is lost.

Therefore, a polyester fiber produced by a high-speed spinning take-off method and having excellent pill resistance and heat stability has not been obtained until now.

An object of the present invention is to provide a polyester fiber produced by a high-speed spinning take-off method and having excellent pill resistance and heat stability.

[Means for solving the problem]

The present inventors have conducted intensive studies to solve the above problems, and as a result, have reached the present invention. That is, the polyester fiber according to the present invention has an intrinsic viscosity [η] of 0.65 or less and a difference (δΔn) between the birefringence at a distance of 0.8 times the radius from the center of the fiber and the birefringence at the center of the fiber (40 × 10 ⁻ ). ³ or more,
The crystalline perfection parameter is 0.3 or less. The toughness (T _F ) of such polyester fibers is 15 or less.

The polyester used in the present invention has a repeating unit of ethylene terephthalate of 90 mol% or more, preferably 95 mol%.
Although ethylene terephthalate is contained as described above, a small amount of the third component may be contained as long as the thermal stability of the obtained fiber is not impaired.

It is known that reducing the toughness of the fiber itself is effective in improving the anti-pill property of the polyester fiber. The toughness here means the energy until the fiber is broken by elongation, and is simply a tensile strength (TS) and a tensile elongation (T ·) obtained by a tensile test.
From the value of E), it can be expressed by the following equation.

Toughness (T _F ) = (T · S) × (T · E) ^1/2 Normal clothing fibers having a T _F of about 30 and T _F = 20 to 25 are used as anti-pill fibers. I have. On the other hand, in the present invention, it was possible to obtain a fiber having an extremely low toughness and an excellent anti-pill having a T _F = 15 or less.

The anti-pill polyester fiber of the present invention having T _F = 15 or less has an intrinsic viscosity [η] of 0.65 or less, and has a birefringence and a birefringence at the center of the fiber at a distance of 0.8 times the radius from the center of the fiber. This is achieved for the first time by a combination of setting the difference δ (Δn) from the ratio to 40 × 10 ⁻³ or more. If any one of these conditions deviates from this condition, the _TF exceeds 15 and it cannot be a polyester fiber having excellent anti-pill properties aimed at by the present invention.

Preferred intrinsic viscosity [η] to obtain lower toughness
Is 0.59 or less, more preferably 0.56 or less.
The lower limit of [η] is not particularly limited, but is preferably 0.40 or more from the viewpoint of spinning stability. Δ (Δn) is 45 × 10
^-3 or more, more preferably 50 × 10 ^-3 or more.
Depending on the combination of [η] of 0.56 or less and δ (Δn) of 50 × 10 ⁻³ or more, _TF of 10 or less can be achieved, and a polyester fiber having extremely excellent pill resistance can be obtained. In view of the fact that the _TF can be reduced to at most 20 even when the intrinsic viscosity is simply reduced to the lower limit of spinning of 0.40, the effect of the combination with the birefringence difference is remarkable.

It is supposed that the low toughness fiber is obtained in the present invention because the orientation distribution occurs due to a large birefringence index difference in the fiber cross section, and the low orientation portion affects the strong elongation of the fiber. You.

The fibers of the present invention need to have a crystal integrity parameter _CR of 0.3 or less.

Crystalline safety parameters C _R is measured by a method described later by X-ray diffraction is a measure for expressing the growth of the crystal region. As the value of C _R is small is advanced growth of the crystal, and that the thermal stability and excellent. As the C _R of the polyester fibers obtained in the normal low speed spinning one drawing seen from is 0.5 or more, the fibers of the present invention has a highly grown crystal structure. The fiber of the present invention having such a crystal structure has a small boiling water shrinkage ratio of, for example, 5% or less, which is sufficient to omit the presetting step performed prior to the wet processing step in the case of fabric. For these reasons,
C _R is required 0.3 or less, preferably 0.25 or less, more preferably 0.2 or less.

Hereinafter, the method for producing the fiber of the present invention will be described. When the fiber of the present invention is melt-spun polyester, a fiber spun with an intrinsic viscosity [η] of 0.65 or less is heated just below the spinneret so that the position of a neck point generated during the spinning process is 30 to 100 cm. A zone is provided, and then the drawing ratio of the neck point of the fiber that has passed through the heating zone (neck drawing ratio) is set to 5.0 or more, and the fiber can be obtained.

The neck point referred to in the present invention is a position where a sharp reduction in fiber diameter occurs during the spinning process, which is observed in high-speed spinning at a take-up speed of 6000 m / min or more. (Journal of the Textile Society of Japan
Vo138, No. 11, 1982, pp. 499-507) The fiber extruded from the spinneret and having an intrinsic viscosity [η] of 0.65 or less is cooled after passing through a heating zone provided immediately below the spinneret. The heating zone can be selected to a suitable length and temperature depending on the fineness of the single yarn and the spinning speed, and in the present invention, the length is 10 to 80.
cm, preferably 20 cm to 70 cm, and a temperature in the range of 100 ° C to 300 ° C, preferably 150 ° C to 250 ° C.

The effect of the heating zone in the present invention is essential for the purpose of determining the structure of the fiber of the present invention and for obtaining stable spinnability.
That is, stable spinning is difficult even if the fiber of the present invention is obtained without providing a heating zone immediately below the spinning port.

As a specific shape of the heating zone, a square or cylindrical heater, etc. can be adopted, but it is not limited to this.

In the spinning of the fiber of the present invention, the condition of the heating zone, specifically, the length of the heating cylinder, the temperature of the heating zone is appropriately selected to adjust the neck point to be 30 to 100 cm below the spinning surface. .

In the spinning method without a heating zone, the position of the neck point is within 30 cm below the spinning surface, and stable spinning is difficult.

If the heating zone is too long or the temperature is too high and the position below the spout surface of the neck point is 100 cm or more, (δΔ
n) is 40 × 10 ⁻³ or less and the tufnel targeted by the present invention
The strength below T _F = 15 cannot be obtained. Therefore, the adjustment of the position of the neck point is extremely important for obtaining a fiber having good spinning stability and a _TF of 15 or less. In order to preferably balance both, it is desirable that the position of the neck point is 40 to 90 cm below the spinning surface.

The fibers exiting the heating zone are cooled to room temperature by cooling air from a cooling chamber. The cooling air used in the present invention is
Cooling air adopted for normal melt spinning at a temperature of 10 to 40 ° C, humidity of 40 to 80% RH, and a wind speed of 0.05 to 0.5 m / sec is applied, and there is no need to use special cooling conditions such as low temperature or high wind speed . As the shape of the chamber, an ordinary horizontal blowing type, a circumferential cooling type adapted to the shape of the spinneret, or the like is adopted.

It is necessary that the fiber exiting the heating zone be drawn with a draw ratio (neck draw ratio) of a neck point generated in the spinning process of 5.0 or more. If the neck stretching ratio is less than 5.0, low strength and thermal stability, which are features of the present invention, cannot be obtained. The preferred take-off speed for obtaining the fibers of the present invention is 8500 m / min or more.

According to the above-mentioned production method, it became possible to obtain the polyester fiber of the present invention having excellent pill resistance and heat stability.

〔Example〕

The present invention will be described in detail with reference to examples. The method for measuring the properties of the polyester fiber of the present invention is described below.

固有 Intrinsic viscosity [η] Using O-chlorophenol as a solvent and variously changing the polymer concentration, ηsp / c is measured, and the value extrapolated to a concentration of 0 is defined as the intrinsic viscosity [η].

◎ Birefringence Using a transmission quantitative interference microscope (manufactured by Kalmts Ice Jena, East Germany), using a green light beam (wavelength: 54.9 mμ), the fiber was obtained from the interference fringe pattern against the electric field vector parallel and perpendicular to the fiber axis by the following method. The refractive index distribution in the inner radial direction is measured and determined.

FIG. 1 shows an example of a pattern of interference fringes of a fiber. First
In the figure, the refractive index of the encapsulant for the fiber is N, the refractive index between points S′-S ″ on the outer periphery of the fiber is n _/ (or _nｎ ), and S′-S ″.
Assuming that the thickness between them is t, the wavelength of the light beam used is λ, the interval between parallel interference fringes in the background (corresponding to 1λ) is D, and the shift of the interference fringes due to the fiber is d, the optical path difference R is Is represented by

Assuming that the radius of the fiber is R, the refractive index n _/ of the fiber at each position is obtained from the optical path difference at each position from the center R _{0 of} the fiber to the outside R.
(Or n _⊥ ) distribution can be obtained. For example, when r is the distance from the center of the fiber to each position, X = r / R =
0, that is, the refractive index at the center of the fiber is n _{/ (0)} (or _{n⊥ (0)} ), and the refractive index at the point of X = 0.8 is n
_/(0.8) (or _{n⊥ (0.8)} ). Seeking birefringence of each position in the _{Δ n = n / -n ⊥,} 0 from the center of the fiber radius.
Birefringence in the 8 times the fiber (X = 0.8) δΔn the difference between the birefringence ([Delta] n ₀₎ of the ([Delta] n _0.8) and fiber center (X = 0)
I do.

That is, δ (Δn) is δ (Δn) = Δn _0.8 −Δn ₀ .

◎ using crystalline integrity parameter C _R X-ray diffractometer, the diffraction angle 2θ in the following conditions the thickness of the sample as approximately 0.5mm drew diffraction intensity curve at 35 DEG from 7 °.

30 kV, 80 mA, scanning speed 1 mm / min, chart speed 10 mm / min, time constant 1 second, receiving slit 0.3 mm.

The three main reflections drawn in the range of 2θ = 17 ° to 26 ° are (100), (010), and (10) from the low angle side.
A diffraction intensity curve between 2θ = 7 ° and 35 ° is connected by a straight line to be a baseline. A perpendicular is drawn between each peak and the baseline, and this perpendicular is defined as the diffraction intensity. (010) and (110)
When the diffraction intensity at the point corresponding to the valley between is defined as I ₀ and the diffraction intensity of the peak of (10) is defined as I, the crystal integrity parameter C _R is represented by the following equation.

◎ toughness T _F Hatsucho 20cm by Toyo Baldwin Co. TENSILON UTM-II-20 type tensile tester at a引波speed 20cm / min,引波strength (T · S) and引波elongation (T · E) Measure and determine by the following formula.

Toughness (T _F ) = (T · S) × (T · E) ^1/2 ◎ Anti-pill property The obtained fibers are plied and crimped as a tow.
It is cut into staples 38 mm long to make short fibers for spinning.
This short fiber is made into a spun yarn of 30th count, knitted with a hand knitting machine (18 gauge), and then tested by the method of JIS-L-1076 (1967). The evaluation is performed by visual judgment, and the occurrence state of the pill is judged according to the following criteria.

Grade 5: Pill formation and little change in appearance are recognized.

Grade 4: Mild pill generation and slight change in appearance.

Grade 3: Moderate pill generation and change in appearance.

Second grade: Generation of pills and change in appearance are considerably recognized.

Primary: Those in which generation of pills and changes in appearance are extremely remarkable.

In addition, if it is a quaternary or higher in the above grades, it can be determined that the anti-pill property is good.

◎ Neck point position The change in the yarn diameter during the spinning process was measured using a wire diameter measuring instrument 460A / 2 made by Zimmer, and the point where the sudden change was exhibited was taken as the neck point and expressed as the distance from the spinning surface. . It was also confirmed by visual observation.

◎ Neck stretching ratio The change in the yarn diameter during the spinning process was measured by a linear measuring device manufactured by Zimmer, and the yarn diameter (d ₁ ) immediately before the neck point and the yarn diameter (d ₂ ) immediately after the neck point were determined.

Example 1 Various polyethylene phthalates having an intrinsic viscosity [η] of fibers shown in Table 1 were extruded at a spinning temperature of 310 ° C. from a spinneret having a hole diameter of 0.35 mmφ and 24 holes. 100m inside diameter just below the spout
A heating cylinder of mφ and a length of 35 cm of an aluminum casting heater heating method was set without a gap between the spinning surface and the heating cylinder, and a heating area was provided. The heating area was 230 ° C.

After exiting the heating zone, the fiber is cooled to room temperature with a cooling air at a cold air temperature of 20 ° C, a humidity of 60% RH, and a wind speed of 0.1 m / sec. Fiber was obtained.

 Table 1 shows the performance of the obtained fibers.

As is apparent from Table 1, if the intrinsic viscosity [η] is 0.65 or less and (δΔn) is 40 × 10 ⁻³ or more, fibers having a toughness of 15 or less can be obtained.

In addition, when the obtained fiber was made into a single-piece knitted fabric and scouring and dyeing of the sample was visually evaluated, no staining spot was found in any of Nos. 1 to 4.

Example 2 Polyethylene terephthalate having an intrinsic viscosity [η] of 0.59 was extruded from a spinneret having a spinning temperature of 300 ° C., a hole diameter of 0.35 mmφ, and 24 holes. A heating cylinder with an aluminum casting heater heating system is installed just below the spinneret so that there is no gap with the spinning surface.
A heating zone at a temperature of 0 ° C. was provided. The heating cylinder had an inner diameter of 110 mm and the length was changed as shown in Table 2.

The fiber exiting the heating zone was solidified under the same conditions as in Example 1 to obtain 50d / 24f fibers at a transaction speed of 10,000 m / min after the oil agent was applied.

 Table 2 shows the performance of the obtained fibers.

As is clear from Table 2, if the neck point is 100 cm or less, the fiber has a toughness of 15 or less, and the pill resistance is good.

[Effects of the Invention] The polyester fiber produced by the high-speed spinning take-off method of the present invention is a polyester fiber having excellent pill resistance and heat stability and good levelness.

In addition, when the obtained fiber was subjected to a knitted fabric, generation of pills was extremely small, and good levelness was obtained.

[Brief description of the drawings]

FIG. 1 is an example of an interference fringe pattern for obtaining a radial refractive index (n / or n _⊥ ) distribution in a cross section of a fiber used for measuring the birefringence of the fiber. In the figure, (a) is a cross-sectional view of the fiber, (b) is an interference fringe pattern, 1 is a fiber, 2 is an interference fringe by an encapsulating agent, and 3 is an interference fringe by a fiber.

Claims (1)

(57) [Claims] The difference (δ (Δn)) between the birefringence at a distance of 0.8 times the radius from the center of the fiber and the birefringence at the center of the fiber (δ (Δn)) is 40 × 10 or less. and at ^-3, the crystalline perfection parameters (C _R) is 0.3 or less, and polyester fiber toughness of the fiber represented by the following formula (T _F) is characterized in that at most 15 T _F = (T S) x (TE) ^1/2 (where TS and TE represent tensile strength and tensile elongation, respectively).