JPS6136101B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to polyester false-twisted yarn, more specifically, polyester false-twisted yarn that has practically sufficient mechanical properties and good dyeability, particularly dyeing under normal pressure and excellent color fastness. Regarding twisted yarn. The polyester used in the present invention consists essentially of polyethylene terephthalate and is obtained by a known polymerization method, but does not contain additives normally used in polyesters, such as matting agents, stabilizers, antistatic agents, etc. But it's okay. There is no particular restriction on the degree of polymerization as long as it is within the range for normal fiber formation, and copolymerization with small amounts of other components is of course possible within a range that does not impair the purpose of the present invention. In addition, the false twisted yarn in the present invention refers to a shape that has an actual number of false twists of 300 times or more per 1 m of yarn length obtained by twisting, heat setting, and untwisting; a shape with a crimp elongation rate of 20% or more. means a stretchable bulky yarn that exhibits Generally, polyester fibers, particularly polyethylene terephthalate fibers, have many excellent properties such as mechanical properties and thermal/mechanical dimensional stability, and are used for various purposes. On the other hand, polyethylene terephthalate fibers have poor dyeability and require special equipment as they must be dyed at high temperatures and pressures around 130°C.
It has drawbacks such as restrictions on its use in combination with fibers such as acrylic whose physical properties deteriorate due to high-pressure dyeing. Several attempts have been made to improve the dyeability of polyethylene terephthalate fibers and to make them dyeable under normal pressure.For example, a method using a carrier during dyeing is known, but it requires a special carrier, and It has drawbacks such as difficulty in processing. In addition, polyethylene terephthalate with improved dyeability is known by copolymerizing metal sulfonate group-containing compounds and polyether, but although these modified polyesters improve dyeability, they are difficult to polymerize and spin. Alternatively, the excellent mechanical properties inherent to polyethylene terephthalate may be degraded, and the color fastness may be poor. After all, when the polymer is chemically modified to make it easier to dye as described above, a third component that can serve as a dyeing seat is mixed into the polymer, so a decrease in excellent heat resistance and mechanical properties is inevitable. The present inventors have overcome the drawbacks of such conventional methods,
As a result of conducting research from a microstructural perspective on polyester fibers, which have good dyeability, can be especially pressure-dyed, and have excellent color fastness, they also have desirable properties. The inventors have discovered that the above object can be achieved by a false twisted yarn having a specific amorphous structure, and have arrived at the present invention. That is, the present invention provides a fiber consisting essentially of polyethylene terephthalate having an initial modulus of 55 g/d or more at 30°C,
The following relationship holds between the peak temperature (T _nax ) and the peak value [(tanδ) _nax ] of the mechanical loss tangent (tanδ) at 110Hz, and (tanδ) _nax is 0.08.
The present invention relates to a polyester fiber that can be dyed under normal pressure and is characterized by the above characteristics. (tan δ) _nax ≧1×10 ⁻² (T _nax −105) However, T _nax is assumed to be in the unit of °C. The above values of T _nax and (tan δ) _nax are suitable as characteristic values expressing the structure of the amorphous region. T _nax is usually located 50°C above the glass transition temperature (tan
δ) _nax is related to the amount of molecular chains in the amorphous region with activated thermal motion at the temperature T _nax . T of the present invention
_nax and (tan δ) _nax means a value related to mechanical absorption (αa absorption) caused by micro-Brownian motion of molecular chains inside the amorphous region. T _nax of conventional polyethylene terephthalate false twisted yarn
is 130℃ or higher, and (tanδ) _nax is 0.14 or lower. As a result of examining the relationship between the structure of the amorphous region of false-twisted yarn and its dyeability, we found that it is possible to dye under normal pressure (the amount of dyeing at 100°C is the same as that of conventional polyethylene terephthalate fiber when dyed under pressure at 130°C). (tan δ) _nax ≧1×10 ^-2
It became clear that (T _nax −105) and (tan δ) _nax ≧0.08, and that the microstructure changes during heating should be small (that is, the microstructure should have high thermal stability). We have arrived at the present invention.
Conventionally, there has been no false-twisted yarn that satisfies the above two conditions using unmodified polyethylene terephthalate, and atmospheric pressure dyeing has been impossible. In false-twisted yarns, the microstructure is thermally stabilized during the false-twisting process, and therefore exhibits a different dyeing behavior than the raw yarn before false-twisting. For example, in the area where T _nax is 105°C or less when the raw yarn is a yarn dyeable under normal pressure, (tan δ) _nax is 0.135 or more (preferably
0.14 or more), and when T _nax is 100°C or less, there is no particular limit to the value of (tan δ) _nax from the viewpoint of normal pressure dyeability, and the larger the (tan δ) _nax , the greater the dyeability. Even in false twisted yarn (tan δ) _nax
The greater the value of T _{nax and the lower the temperature of T nax} , the more remarkable the ease of dyeing becomes, but in order for normal pressure dyeing to be possible, at least the above-mentioned conditions must be satisfied. Generally, when false twisting is performed at a temperature of 180°C or higher, the above conditions are almost satisfied. In order to satisfy the above conditions, for example, the raw yarn before false twisting is wound at a spinning speed of 4000 m/min or more, and then subjected to dry heat treatment for a short time (less than 1 second) at a high temperature (usually 240°C or more). or heat treated with superheated steam. When false-twisting undrawn yarn obtained at a spinning speed of 4000 m/min or less or drawn yarn that has been subsequently drawn, there is little change in dyeability during false-twisting, excellent heat fixability, and crimping caused by external loads. In order to reduce the loss of , the heat setting temperature in the twisting-heat-setting-untwisting process is usually 215° C. or lower and 150° C. or higher, and the load is 0.15 g/dTex or higher and 0.5 g/dTex or lower. The false twisted yarn obtained under these conditions has a T _nax of approximately 135°C, a (tan δ) _nax of approximately 0.10,
Its dyeability is almost the same as that of the raw yarn before false twisting, or it is slightly easier to dye, but it cannot be said to be dyeable under normal pressure. In order to further enhance dyeability of the false twisted yarn of the present invention, it is preferable that T _nax is 115° C. or less and (tan δ) _nax is 0.12 or more. However, in this case, development of crystalline regions is essential to increase the thermal stability of the structure. In the present invention, the initial modulus at 30℃ is required to obtain mechanical properties as a polyester.
It is necessary that it is 55 g/d or more. For this purpose, it is usually sufficient that the average birefringence Δn is 35×10 ⁻³ or more, but this condition is not necessarily a necessary and sufficient condition for providing an initial modulus of 55 g/d or more. Sufficient conditions for 55 g/d or more are that the value of Δn is 45×10 ⁻³ or more, and (tan δ) _nax is 0.5 or less. here
The initial modulus at 30°C is expressed as the dynamic elastic modulus (E′ ₃₀ ) at 30°C. As (tan δ) _nax increases, E′ ₃₀ generally needs to increase to maintain shape retention. If E′ ₃₀ is 55
If it is less than g/d, the thermal stability of the microstructure will decrease, the dimensional stability will also be poor, and the fiber will become soft. The crystallinity (χ
c), the size of microcrystals on the (010) plane (ACS), and the degree of crystal orientation on the (010) plane (Co) are all strongly correlated with external deformation into fibers and thermal stability of the structure. . The false twisted yarn of the present invention has sufficient strength (3 g/d or more) as a polyester crimped yarn, elongation after stretching the crimp (20 to 60%), and initial modulus (55 g/d or more). To have χc is 30
% or more ACS is 38 Å or more and Co is preferably 80% or more. More preferably, χc is 75% or more,
ACS is 45 Å or more and Co is 85% or more. Here, χc, ACS, and Co are values measured by X-ray diffraction using the methods described below. In conventional false twisted yarn, χc is 20-30%, ACS is about 30Å, and Co is about 85%.
%. A typical example of producing the false twisted yarn of the present invention is shown below. That is, undrawn polyethylene terephthalate yarn wound at a spinning speed of 5000 m/min was heated to a surface temperature of 255 m/min.
After heat treatment for 0.6 seconds without contact in a tube heater at ℃, under an overfeed rate of 5%.
It is false twisted at 200℃. Next, when producing the false twisted processed yarn of the present invention, the structural characteristics required of the raw yarn before processing will be described. Peak value of tanδ (tanδ) _nax is 0.10 or more, T _nax
is 110° C. or less, Δn is 35×10 ⁻³ or more and 150×10 ⁻³ or less, and the initial modulus is 50 g/d or more, which are preferable from the viewpoint of atmospheric pressure dyeing of the false twisted yarn. Furthermore, if the center average refractive index (n(0)) of polarized light with an electric field vector in the fiber axis direction is smaller than 1.70 and 1.65 or more, the false twist for clothing has appropriate elongation (20-60%) and dyeability. It is more preferable as a raw yarn that can supply processed yarn. Average birefringence (Δn) of the false twisted yarn of the present invention
are necessary conditions for the fiber of the present invention to have an initial modulus of 55 g/d or more at 30 ° C.
It needs to be 35×10 ^-3 or more. On the other hand, from the viewpoint of thermal stability of the structure against temperature changes, it is desirable that it is 50 × 10 ^-3 or more, and from the viewpoint of dyeability and color fastness, it is preferably 110 × 10 ^-3 or less, and even more preferably 85 × 10 ^-3 or less. Δn is 110
×10 ^-3 or less, the reduction rate of dynamic elastic modulus (E′) in the temperature range of 150 to 220°C (E′ at 150°C and 220°C are respectively E′ ₁₅₀ and E′ ₂₂₀ , and E′ ₂₂₀ /E' ₁₅₀ ) becomes smaller, and E' ₂₂₀ /E' ₁₅₀ becomes larger than 0.75. In other words, the structure becomes stable against heat.
The color fastness is also improved. Furthermore, Δn is 85×
Those smaller than 10 ^-3 have extremely excellent atmospheric dyeability. Δn of conventional false twisted yarn is 120×
10 ^-3 or more, compared to Δ of the false twisted yarn of the present invention.
One of the microstructural features is that n is extremely small. Average refractive index (n〓(0)) at the center of the yarn before false twisting and refractive index n〓(0.8) or n〓 at a distance of 0.8 times the radius from the center of the fiber in an interference micrograph. If the local average refractive index distribution of the fiber, which satisfies the following relationship between (-0.8), is symmetrical with respect to the center of the fiber, the heat setting temperature range during false twisting is set wide Furthermore, the resulting processed yarn has fewer dyeing spots, strong elongation spots, etc. Here, if the local average refractive index distribution is symmetrical with respect to the center of the fiber, the minimum value of the average refractive index n〓 is (n〓(0)-10×10 ^-3 ) or more, And the difference between n〓(-0.8) and n〓(0.8) is 50
This means the case of ×10 ^-3 or less. Furthermore, the above n〓
(0), n〓(0.8), n〓(−0.8), Δn(0.8−
0), Δn, etc., were measured using an interference microscope using a method described later. In addition, in the processed yarn of the present invention, the smaller the mechanical loss tangent (tan δ ₂₂₀ ) at 220°C, the lower the mechanical loss tangent at 200°C.
This is a preferable direction since the initial modulus decreases little as the temperature increases in the vicinity. When tan δ ₂₂₀ is 0.25 or less, the amount of decrease in the initial modulus as the temperature increases becomes significantly small. In other words, the fiber has a structure that is extremely stable against heat. During spinning, the cooling solidification and thinning deformation of the polymer flow spun from the spinneret are controlled by appropriately adjusting the polymer viscosity, spinning temperature, atmospheric conditions under the spinneret, cooling method, take-up speed, etc. Thus, fibers with good spinnability and desired properties can be obtained. In particular, it is important to control the cooling and solidification of the spun yarn, and in order to obtain spinnability and desired properties, rapid cooling and solidification, especially cooling and solidification using low-temperature cooling air perpendicular to the yarn from one direction, is not very desirable. . Note that the take-up speed here refers to the speed of the first drive roll at which the yarn, which has been cooled and solidified after spinning, is taken off after being further bundled, treated with oil, etc., if necessary. FIG. 1 shows an example of an apparatus for producing raw yarn before false twisting used in Examples. The molten polyester is spun from a spinneret (not shown) in a heated spinning head 2 and cooled in the atmosphere to form yarn 1. At this time, a tubular heating area 3 surrounding the spun yarn is provided below the spinneret, and a fluid suction device 4 for cooling and suctioning the yarn is provided below it. The yarn that has passed through the tubular heating zone and the fluid suction device passes through an oil application device 5 and a convergence device 6, and then is taken off by a take-off roll 7. Once taken off, the yarn is taken off by a take-up roll 8 and then continuously or discontinuously passed through a non-contact heating tube 9 controlled within ±0.5°C.
, and is taken up by a take-up roll 10. At this time, the yarn is drawn by 0 to 5% by adjusting the rotational speed of the rolls 8 and 10. The yarn is false-twisted using a conventional false-twisting machine shown in FIG.
The false twisted yarn of the present invention can be dyed under normal pressure (100
It has good dyeability even at temperatures (°C) and its unique fine structure causes little structural change even when heat is applied during the product manufacturing process, making it particularly useful as a clothing fiber. The method for measuring the structural properties of the fibers of the present invention will be described below. <Mechanical loss tangent (tan δ) and dynamic elastic modulus (E')> Sample amount 0.1 to 1 mg was measured using a Rheo-vibron DDV-c type dynamic viscoelasticity measuring device manufactured by Toyo Baldwin Co., Ltd. Frequency 110Hz,
Tan δ and E′ at each temperature are measured under strain within the linear range in dry air at a heating rate of 10°C/min. The tan δ peak temperature (T _nax ) (° C.) and the same peak height [(tan δ) _nax ] are obtained from the tan δ-temperature curve. FIG. 3 shows the false twisted yarn A of the present invention, the raw yarn B before false twisting of the present invention, and the conventional false twisted yarn C;
Typical examples of the tan δ-temperature curve (Figure 3a) and the E'-temperature curve (Figure 3b) are schematically shown. <Average refractive index (n〓, n⊥) and average birefringence Δn> Fibers are measured by the interference fringe method using a transmission quantitative interference microscope (for example, interference microscope Interfaco manufactured by Karl Zeiss Jena, East Germany). The distribution of the average refractive index observed from the surface can be measured. This method applies to fibers with a circular cross section. The refractive index of a fiber is characterized by the refractive index n〓 for polarized light with an electric field vector parallel to the fiber axis, and the refractive index n⊥ for polarized light with an electric field vector perpendicular to the fiber axis. All measurements described here are performed using green light (wavelength λ =
549mμ) is used. A mounting medium that has a refractive index (N) that provides a shift in interference fringes within a range of 0.2 to 2 wavelengths and is inert to the fibers is injected between an optically uniform slide glass and a cover glass. , immerse the sample fiber in the mounting medium. The fiber is placed so that its axis is perpendicular to the optical axis of the interference microscope and the interference fringes. This pattern of interference fringes is photographed and approx.
Analyze at 1500x magnification. In Figure 4, the refractive index of the fiber encapsulant is N, and the refractive index between points S〓 and S〓 on the outer periphery of the fiber is n〓 (or n
⊥), the thickness between S〓 and S〓 is t, the wavelength of the light beam used is λ, and the distance between parallel interference fringes in the background (1
(equivalent to
(or n⊥)-N)t. Therefore, n〓 (or n⊥)=Γ/d+N holds true. If the cross-sectional shape of the fiber is circular, the thickness t is given by 2√ ² − ² using the coordinate x and the radius R. When the radius of the fiber is R, the distribution of the refractive index n〓 (or n⊥) of the fiber at each position can be determined from the optical path difference at each position from the center 0 to the outer periphery R of the fiber. When x is the distance from the center of the fiber to each position, X=x/R=0, that is, the refractive index at the center of the fiber is the average refractive index (n〓(0) or n
It is called ⊥(0)). X is 1 on the outer periphery and takes a value between 0 and 1 on the other parts. For example, the refractive index at the point where X=0.8 is expressed as n〓(0.8) (or n⊥(0.8)). Also, the average refractive index n〓
(0) and n⊥(0), the average birefringence (Δn)
is expressed as Δn=n〓(0)−n⊥(0). FIG. 5 shows the distribution of n〓 of the conventional false-twisted yarn B, the processed yarn A of the present invention, and the raw yarn C before false twisting. In Figure 5, the horizontal axis indicates the distance from the center
x/R, and the n〓 value is displayed on the vertical axis. X=0 is the center of the fiber, and X=1 and X=-1 are points on the outer periphery of the fiber. In the case of a non-circular cross section, the thickness t cannot be given as a function of only R and x, so a separately measured value is used. As a method for measuring t, the type of mounting medium is changed and it is calculated from the measured value of Γ obtained using each mounting medium using the following formula. t=(Γ ₁ - Γ ₂ )/(N ₂ - _{N 1} ) Here, N ₁ and N ₂ are the refractive index of the mounting medium 1 and 2, Γ
₁ and Γ ₂ are the retardations measured in mounting medium 1 and 2. <Size of microcrystals (ACS)> The X-ray diffraction intensity in the equator direction is measured using the symmetric reflection method, and the diffraction angle dependence curve of the X-ray diffraction intensity is calculated.
ACS is calculated. The X-ray diffraction intensity was measured using an X-ray generator (RU-200PL) manufactured by Rigaku Corporation and a goniometer (SG-9R).
A scintillation counter is used as the counter, a pulse height analyzer is used as the counting section, and the measurement is performed using a Cu-K line (wavelength λ = 1.5418 Å) made monochromatic with a nickel filter. The fiber sample was placed in an aluminum sample holder so that the fiber axis was perpendicular to the X-ray diffraction plane. At this time, the thickness of the sample is set to approximately 0.5 m/m. 30kV,
Operate the X-ray generator at 80 mA, scanning speed 1°/min, chart speed 10 mm/min, time constant 1 second, divergent slit 1/2.
゜, receiving slit 0.3m/m, scattering slit 1/2゜, 2θ is 35゜~
Record the diffraction intensity up to 7°. The full scale of the recorder is set so that the resulting diffraction intensity curve falls within the scale. Polyethylene terephthalate fibers generally have three major reflections in the range of equatorial diffraction angles 2θ=7° to 26°. From the low angle side (100),
They are (010) and (110) planes. To find ACS, for example, "Polymer X-ray Diffraction" by LE Alexander
Kagaku Doujin Publishing, Chapter 7 Using Scherrer's equation. A straight line connects the diffraction intensity curves between 2θ=7° and 2θ=35° to form a baseline. Drop a perpendicular line from the top of the diffraction peak to the baseline, and draw the midpoint between the peak and the baseline on this perpendicular line. A horizontal line through the midpoint is drawn between the diffraction intensity curves and the diffraction peaks. If the principal reflections are well separated, they will intersect two shoulders of the peak of the curve, but if they are poorly separated, they will intersect only one shoulder. Measure the width of this peak. If it intersects only one shoulder, measure the distance between the intersecting point and the midpoint and double it. If it crosses two shoulders, measure the distance between both shoulders. These measured values are converted into radians and used as the line width. Furthermore, this line width is corrected using the following equation. β=√ ² − ² B is an actual value of the line width, and b is a broadening constant, which is the line width (half width) in radians of the peak of (111) plane reflection of a silicon single crystal.
The crystallite size (ACS) is given by ACS(Å)=K·λ/βcosθ. Here, K is 1, λ is the wavelength of the X-ray (1.5418 Å), β is the line width after correction, and θ is the Bragg angle, which is 1/2 of the diffraction angle 2θ. <Crystallinity (χc)> X obtained in the same manner as the measurement of the size of microcrystals
From the line diffraction intensity curve, a straight line connects the diffraction intensity curves of 2θ=7° and 2θ=35° to form a baseline. As shown in Figure 6, the valley around 2θ = 20° is the apex, connected by a straight line along the base of the low-angle side and the high-angle side, separated into a crystalline part and an amorphous part, and calculated by the area method according to the following formula. Determine the degree of crystallinity χc. χc = Scattering intensity of crystal part / Total scattering intensity x 100 (%) <Crystal orientation degree (Co)> Rigaku Corporation X-ray generator (RU-200PL), fiber sample measuring device (FS-3), goniometer (SG-9), a scintillation counter is used for the counter, a pulse height analyzer is used for the counting part, and the Cu-K〓 line (wavelength λ =
1.5418 Å) to measure the X-ray diffraction intensity curve in the azimuthal direction. Polyethylene terephthalate fibers generally have three main types of reflection on the equator line, and (010) plane reflection is used to measure the degree of crystal orientation (Co).
The diffraction angle 2θ of the (010) plane is determined from the diffraction intensity curve in the equatorial direction. The aforementioned X-ray generator
Operates at 30kV, 20mA. For fiber sample measurement equipment,
Attach the sample fibers so that they are parallel to each other. Adjust the thickness of the sample to approximately 0.5m/m. The goniometer is set at the 2θ value determined from the equatorial diffraction intensity curve. Using the symmetrical transmission method, the azimuthal direction is scanned from −30 to +30° and the diffraction intensity in the azimuthal direction is recorded. Furthermore, the diffraction intensity in the azimuth directions of −180° and +180° is recorded.
At this time, scanning speed 4°/min, chart speed 10m/m/min, time constant 1 second, collimator 2m/mφ, receiving slit vertical width
It has a width of 19m/m and a width of 3.5m/m. To determine Co from the obtained diffraction intensity curve in the azimuthal direction, first take the average value of the diffraction intensities obtained at ±180°, and use the horizontal line passing through this value as the baseline. Draw a perpendicular line from the top of the peak to the baseline and find the midpoint of its height. A horizontal line passing through the midpoint is drawn, the distance between the two intersections of this and the diffraction intensity curve is measured, and this value is converted into an angle (°) and the value is defined as the orientation angle H (°). The degree of crystal orientation is given by Co (%) = (180° - H)/180° x 100. <Dyeability> Dyeability was evaluated by equilibrium dyeing rate. Disperse dye Resolin Blue (Resolin Blue) FBL
(trade name of Bayer), dyeing was carried out at 100°C with 3% owf and a bath ratio of 1:50. Disper as a dispersant
Add 1g/TL and further adjust pH to 6 with acetic acid.
Adjust to. The dyeing rate is determined by collecting the dye solution after a predetermined time (2 hours), calculating the amount of dye in the remaining solution from the absorbance, and subtracting this from the amount of dye used for dyeing. The percentage (%) was calculated. In addition, as a sample for dyeing, the original yarn was knitted into a piece of fabric, which was scoured at 60°C for 20 minutes using a score roll FC2g/, dried, and controlled in humidity (20°C x 65% RH). <Dyeing fastness> A sample was dyed in the same manner as in the stainability evaluation except that the staining concentration was 1% owf and the staining time was 90 minutes. Hydrosulfite 1g/, sodium hydroxide 1g/, surfactant ( Sunmaur RC-
700) 1 g/, and was subjected to reduction cleaning at 80° C. for 20 minutes at a bath ratio of 1:50. Regarding color fastness, light fastness (JIS L-
1044), abrasion fastness (based on JIS L-0849), hot pressing fastness (JIS L-0849)
0850) was evaluated. <Initial modulus> At 30℃ obtained from the dynamic viscoelasticity measurement mentioned above
The value of E′ was taken as the initial modulus at 30°C. <Strong elongation> TENSILON UTM− manufactured by Toyo Baldwin Co., Ltd.
Measurement was performed using a -20 type tensile testing machine at an initial length of 5 cm (however, the length after stretching the crimp) and a tensile speed of 20 mm/min. <Crimp form retention rate> Among the crimp development rates disclosed in JP _- A No. 48-35112, CD _5.0 is used. That is, first, the CD _5.0 of the textured yarn obtained in the drawing and false twisting process is measured _, and the value is set as α. Next, the processed yarn is immersed in boiling water at 100° C. for 1 minute while applying a load of 0.1 g/d. Next, the free end is naturally dried in an atmosphere of 20° C. and 60% RH and left in the atmosphere for 24 hours. Next, CD _5.0 is measured again and _the value is set as β, then the crimp form retention rate of the processed yarn is expressed as β/α×100 (%). Normally, if this retention rate is 65% or more, it is determined that the crimp shape retention is good. Example 1 Polyethylene terephthalate having an intrinsic viscosity [η] of 0.63 measured at 35°C in a 2/1 mixed solvent of phenol/tetrachloroethane was spun at a spinning temperature of 300°C using a spinneret with a pore diameter of 0.35 m/mφ and 7 holes. broth,
The spun filament is cooled and solidified by a flow of air at 22℃ supplied parallel to the running direction of the yarn, then a finishing agent is applied and the yarn is spun at a speed of 3000 m/min to 9000 m/min. A fiber of 35d/7f was obtained by winding. Next, this fiber was heated in a heating tube (the first
Heat treatment was performed in 9) of the figure in a non-contact state for 0.6 seconds at a degree of elongation of -2%. The yarn after the heat treatment is designated as 11 in Figure 2.
to be installed. The length of the 14 false twist heaters in Fig. 2 is 1 m,
False twisting heater temperature 200℃, stabilizer heater 17 in Figure 2 diameter 4m/mφ, heater length 0.6
m, and the heater temperature was set at 190°C. Figure 2: The ratio of the surface speeds of roll 16 and roll 13 is 1.125,
Number of twists: 3500t/m, yarn speed at roll 16: 146m/
Min., winding rate 4.3%, stabilization feed rate 16%
It was false twisted. The structure and physical properties of the obtained false twisted yarn are summarized in Table 1. In Table 1, sample 1 is a comparative example, with a small E′ ₃₀ of 40 g/d.
Dimensional stability is poor and elongation is too high. Moreover, the equilibrium dyeing rate is 68%, so it cannot be said that it can be dyed under normal pressure. If the equilibrium dyeing rate is 80%, it is almost equivalent to dyeing under pressure at 130°C. Therefore, the false twisted yarn of the present invention having an equilibrium dyeing rate of 80% or more is a yarn dyeable under normal pressure.

【table】

【table】 [Brief explanation of the drawing]

FIG. 1 is a diagram schematically showing an apparatus for producing yarn for the false-twisted yarn of the present invention, FIG. 2 is a schematic diagram showing a typical example of a false-twisting machine, and FIGS. Diagram b
are graphs showing the temperature dependence of mechanical loss tangent (tanδ) and dynamic elastic modulus (E′), respectively;
is the false twisted yarn of the present invention, B is the raw yarn before false twisting, C is
4 is an example of the pattern of interference fringes used to measure the radial refractive index (n〓 or n⊥) distribution in the cross-section of the fiber, a is a cross-sectional view of the fiber, and b is a cross-sectional view of the fiber. Interference fringe patterns, 1 shows interference fringes caused by fibers, 2 shows interference fringes caused by encapsulant, 3 shows interference fringes caused by fibers, and FIG. An example of the distribution of n〓, where A is the false twisted yarn of the present invention, B is the conventional false twisted yarn, C is the raw yarn before false twisting, and Figure 6 is the X-ray diffraction intensity of polyethylene terephthalate fiber. It is a graph showing an example of a curve. 1 and 2, 1 is a yarn, 2 is a spinning head, 3 is a tubular heating area, 4 is a fluid suction device, 5 is an oil application device, 6 is a convergence device, 7, 8,
10 is a take-up roll, 9 is a heating cylinder, 13 is a feed roll, 14 is a false twisting heater, 15 is a spindle,
16 and 18 are take-up rolls, and 17 is a stabilizer heater.

Claims (1)

[Claims] 1 A fiber consisting essentially of polyethylene terephthalate with an initial modulus of 55 g/d or more at 30°C, the peak temperature (T _nax ) of mechanical loss tangent (tan δ) at a measurement frequency of 110 Hz (°C )
and the peak value of tan δ [(tan δ) _nax ], which satisfies the following formula, and is characterized in that (tan δ) _nax is 0.08 or more. (tan δ) _nax ≧1 × 10 ^-2 (T _nax -105) 2 The average birefringence (Δn) is 110 × 10 ^-3 or less and 45 × 10 ^-3 or more as described in claim 1 Polyester false twisted yarn. 3 A fiber consisting essentially of polyethylene terephthalate with an initial modulus of 55 g/d or more at 30°C, whose tan δ peak temperature (T _nax ) at a measurement frequency of 110 Hz is 115° C. or less, and whose peak value [(tan δ ) _nax ] is 0.12 or more, the crystallinity (χc) is 33% or more, the (010) crystallite size (ACS) is 38 Å or more, and the (010) crystal orientation (Co ) is 80% or more, the polyester false-twisted yarn according to claim 1. 4 Δn is 45×10 ^-3 or more, T _nax is 105°C or less, (tan δ) _nax is 0.11 or more, χc is 70% or more, and the size of the (010) plane microcrystal (ACS ) is 50 Å or more, and the degree of crystal orientation (Co) of the (010) plane is 85% or more.