JPH01314721A - Polyester yarn and production thereof - Google Patents

Abstract

PURPOSE:To obtain the subject high-melting yarn, excellent in heat resistance and elongation recovery properties and suitable for napped fabrics by heating polyethylene terephthalate in a heating zone at a specific temperature or above provided just under a spinneret and spinning a yarn while keeping the neck deformation ratio of the resultant yarn within a specified range. CONSTITUTION:A polyester substantially consisting of polyethylene terephthalate is spun at >=9000m/min, preferably 10000-12000m/min speed. In the process, a heating zone at >=250 deg.C is provided just under a spinneret and the neck deformation ratio of the yarn formed in the spinning process is kept within the range expressed by the formula 3X10<-3>S-0.5<=N<=15X10<-3>S-5.5, provided that N>=2 (N is the neck deformation ratio; S is the specific surface area (cm<2>/g) of the single filament) to carry out spinning and afford the objective yarn having >=275 deg.C melting peak temperature measured by using a differential scanning calorimeter(DSC) and <=0.03 ( na) birefringence ratio of an amorphous part and <=0.04 birefringence difference (delta n) in the filament cross section.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a polyester yarn with excellent heat resistance and mechanical properties, and a method for producing the same. More specifically, the present invention relates to a polyester yarn having a high melting point and excellent stretch recovery properties and suitable for use in raised fabrics, and a method for stably producing the same.

[Prior art and problems to be solved by the invention] In recent years, high-speed spinning methods have been proposed for the purpose of obtaining polyester yarns with high productivity, and their practical application is being considered. Japanese Unexamined Patent Publication No. 1983
It is stated in Japanese Patent Publication No. 121613 and Japanese Patent Publication No. 60-47928 that polyester yarn obtained at a spinning speed of 5,000 to 6,000 m/min or higher can be used for practical purposes such as knitting and weaving without the need for a drawing process. It is shown. Even higher productivity is expected if the spinning speed is 7,000 m/min or higher. However, when spinning a polyester yarn consisting essentially of polyethylene terephthalate at such a high speed, yarn breakage during spinning increases as the spinning speed increases.
Problems arise that make intensive production difficult. Special Public Service 1986-
The spinning speed of the polyester yarn exemplified in Japanese Patent No. 47928 is also up to 9,000 m/min. Textile Society Journal VOL, 37. Ik 4 (1981) T-136
D shows the fiber microstructure of polyester yarn obtained by spinning speeds up to 9.000 m/min;
Nothing is indicated regarding speeds of 9,000 m/min or more.

Dietrich et al., r chemiefasern/
In Textili-ndustrie J magazine September 1982 issue P-612-625, 10,000 polyester yarns consisting essentially of polyethylene terephthalate were
It describes the difficulty of stably producing fibers at an industrial level without yarn breakage at spinning speeds exceeding m/min.

Recently, a method of spinning at a spinning speed exceeding 10,000 m/min has been proposed in Japanese Patent Application Laid-Open No. 63-59412, but these are related to methods for spinning modified polyester, and essentially polyethylene Only yarns that lack the heat resistance and other features of polyester yarns made of terephthalate have been obtained. Also, JP-A-62-263S09, JP-A-62-263S
No. 15 proposes a method and yarn for spinning polyethylene terephthalate at a spinning speed of up to 13,000 m/min. However, the fibers obtained by this method have extremely amorphous microstructures, so they have poor heat resistance, high elongation at break, poor recovery from repeated elongation strain, and poor mechanical properties. There is a drawback that it cannot be used for knitted fabrics.

The present invention provides a method for stably spinning polyester yarn at an industrial level at high speed spinning of over 9,000 m/min without substantially impairing the characteristics of polyethylene terephthalate, and a novel polyester yarn obtained thereby. The purpose is to

[Means to solve the problem]

The present inventors have intensively investigated the relationship between the spinning stability during spinning and the fine structure of the resulting yarn at a spinning speed of 9,000 m/min or more, and as a result, the inventors have found that manufacturing within the range specified in the present invention is possible. The present inventors have discovered that extremely stable spinning can be achieved, and as a result, a polyester yarn with excellent heat resistance and mechanical properties can be obtained, leading to the completion of the present invention.

That is, the object of the present invention is to have a differential scanning calorimeter DSC melting peak temperature of 275°C or higher, an amorphous birefringence index (Δna) of 0.03 or lower, and a birefringence difference (δΔn) within the filament cross section of 0. A preferred method for obtaining such a polyester yarn is to spin a polyester consisting essentially of polyethylene terephthalate at a speed of 9,000 m/min or more, by spinning a polyester yarn immediately below the spinneret. This is an ultra-high speed spinning method for polyester yarn, which is characterized in that a heating region of 250° C. or higher is provided in the spinning process, and the neck deformation ratio of the yarn generated during the spinning process is set in the range shown by the following formula.

3X10-S-0,5≦N≦15X10-'S-5.5
A polyester consisting essentially of polyethylene terephthalate containing 95 mol% or more of phthalate repeating units, but containing small amounts of matting agents, antistatic agents, stabilizers, etc. within the range that does not impair heat resistance, weather resistance, etc. Also good.

The heat resistance of the polyester yarn of the present invention is typically indicated by the DSC melting point, which is determined by the measurement method described below. DS
It can be said that the higher the C melting point, the better the heat resistance. The polyester yarn of the present invention has a DSC melting point peak temperature (DSC
melting point peak) is 275°C or higher. Compared to the DSC melting point peak of 255°C to 260°C of conventional low-speed spinning/drawn yarn, this has an extremely high melting point and excellent heat resistance.

The melting point obtained with the polyester yarn of the present invention is up to 283
reach ℃. Comparison with the fact that the equilibrium melting point of polyethylene terephthalate is 286° C. confirms that the polyester yarn of the present invention has high crystalline integrity.

When the polyester yarn of the present invention having a high melting point is used for knitted fabrics obtained using the yarn, particularly for pleated fabrics, it can be used in the heat setting process at 180°C to 220°C employed in the processing process. Even in this case, a napped fabric with a deep surface condition can be obtained without any occurrence of heckling due to the napping state.

The polyester yarn of the present invention has an amorphous birefringence (Δn2
) is required to be 0.03 or less.

In high-speed spinning, Δna is a spinning speed of approximately 6,000 m/
It is expected that the tendency will be that it will tend to decrease as the speed increases, with the peak at 100 min.
37. It4 (1981) T-136), 9,0
In the area exceeding 00 m7 minutes, Δn3 was unknown because it was impossible to collect the yarn itself. On the other hand, according to the report, it is predicted that mechanical properties such as yarn strength and elongation will decrease as Δn3 decreases, which is considered to be an unfavorable trend from a practical standpoint. Ta. In contrast, in the present invention, the birefringence distribution within the filament cross section (
It was found that when δΔn) is 0.04 or less, the mechanical properties are improved as Δn3 is smaller.

That is, the polyester yarn of the present invention has Δn1 of 0.03.
It is characterized by the combination of δΔn being 0.04 or less and δΔn being 0.04 or less. The mechanical properties of the polyester yarn of the present invention are exhibited as a dramatic improvement in the recovery characteristics of the yarn against repeated stretching.

When the yarn is put to practical use as a knitted fabric, a mechanical action that causes the yarn to stretch by 1 to 2% is applied during processing and finishing steps. For example, in the production of raised fabric, the threads on the fabric are mechanically subjected to a raised process several times in order to improve the surface properties of the fabric. At this time, if the stretch recovery property of the yarn is poor, the yarn itself will undergo dimensional changes, and the surface properties of the fabric will be significantly impaired. In order to prevent such surface damage, it is necessary that the elongation recovery rate measured by the method described below be 90% or more. If the elongation recovery rate is 95% or more, a raised fabric with even better surface properties can be obtained.

The polyester yarn of the present invention has an elongation recovery rate of 90% or more, and the yarn length does not change even after elongation 7 in such a processing step, and a raised fabric with excellent surface properties can be obtained. . Such improvement in mechanical properties is better as Δn3 is smaller and as δΔn is smaller. In particular, Δn,
When l is 0.02 or less and δΔn is 0.03 or less, the yarn has excellent stretch recovery properties that exceed that of conventional low speed spun and drawn yarns.

Although the single yarn denier of the polyester yarn of the present invention is not particularly limited, it is preferable that the single yarn has a denier of 1 to 5 denier because it is effective in improving the surface properties when made into a raised fabric.

The manufacturing method of the present invention will be explained below.

The present invention requires a spinning speed of 9,000 m/min or more. At a spinning speed of less than 9,000 m/min, the polyester yarn targeted by the present invention cannot be obtained no matter how the spinning conditions are selected. The preferred range of spinning speed is 10,0
00 m/min to 12,000 m/min.

At speeds exceeding 13,000 m/min, the winding equipment becomes complicated and is difficult in practice.

In the present invention, the yarn discharged from the spinneret is heated in a heating area of 250° C. or higher provided directly below the spinneret, and neck deformation is caused in the yarn at a neck deformation ratio specified in the claimed range. After that, it is necessary to wind it up without stretching it. Here, the neck deformation ratio refers to, as will be described later, when polyester yarn is spun at a high speed exceeding approximately 6,000 m/min, the diameter of each single yarn rapidly becomes thinner on the spinning line, resulting in a "necking". This is a value that indicates the degree of thinning when deformed into a shape, expressed as an area ratio.

The present inventors have repeatedly studied the neck deformation magnification and found that the deformation magnification is not uniformly determined by the spinning speed, but can be changed depending on the spinning conditions. Specifically, it was found that the temperature changes depending on the temperature of the heating area directly under the spinneret. It has also been found that at a constant spinning speed and temperature, the specific surface area of the single fiber being spun is proportional to the specific surface area. Furthermore, this neck deformation ratio is closely related to the spinning stability and the fine structure of the obtained polyester yarn, and from this study, it was possible to specify the neck deformation ratio that can make the polyester yarn of the present invention have good spinning stability. Ta.

FIG. 1 shows the neck deformation magnification specified by the present invention. In FIG. 1, the horizontal axis is the specific surface area of the single yarn. The specific surface area is the surface area per unit weight (cm2/g) calculated from the single yarn denier, cross-sectional shape, and density. The vertical axis is the neck deformation magnification obtained by actually measuring the change in yarn diameter of a single yarn during spinning.

In FIG. 1, the range surrounded by straight lines A and B is the range of the present invention. Above straight line A, thread breakage occurs frequently during spinning, making stable spinning difficult.

Below straight line B, the DSC melting point becomes low and the polyester yarn of the present invention cannot be obtained.

The neck deformation ratio of the present invention is achieved by providing a heating region of 250° C. or more directly below the spinneret for the yarn discharged from the spinneret. When the temperature of the heating area is less than 250℃, the neck deformation magnification becomes higher than the straight line in Figure 1,
The invention is not achieved.

The specific installation of the heating zone is achieved by connecting a tube with a heating source directly below the spinneret. Heat sources include cast aluminum heaters, far-infrared heaters, and hot air, but these may also be used in combination.

The length of the tube is set depending on the spinning conditions, but it is usually 20~
100cm is adopted.

The temperature of the heating zone is approximately 5.5 mm below the spinneret surface inside the cylinder.
cm, which is the temperature detected by a thermometer placed approximately 2 cm away from the yarn.

The yarn that has left the heating area is then cooled to room temperature by a normal cross-blown chamber, a vertically-blown cooling tube, or cooling air parallel to the yarn, but neck-shaped deformation occurs during this process. After the neck-shaped deformation has been completed and the yarn has been cooled to room temperature, the yarn is bundled, oiled, and then wound on a winder without being stretched.

〔Example〕

Hereinafter, the present invention will be explained in more detail with reference to Examples.

In addition, in the examples, each characteristic value used was measured by the following method.

(a) Differential scanning calorimeter DSCSC melting beak Using a DSC-n type differential calorimeter manufactured by Birkin Elma, 20℃/
The temperature was raised at a heating rate of 10 minutes, and the peak temperature of the melting point curve of the DSC curve was determined as the melting point temperature.

(b) Difference in birefringence within the filament cross section δΔnThe refractive index parallel to the fiber axis (
From the refractive index perpendicular to n, , ), the birefringence Δn =
Find n tt n, and calculate this from the fiber center ΔnrO to the outer circumference Δn in the cross section of the single yarn.

I asked for it. The birefringence difference δΔn in the cross section of the filament was determined by the following equation.

δΔn−Δ11rxb, δ1. -Δnr0 (c) Amorphous birefringence Δn3 2θ=approximately 26 using a wide-angle X-ray diffraction device manufactured by Rigaku Denki Co., Ltd.
The crystal orientation function fc was determined by a conventional method from the diffraction whitening curve in the azimuthal direction at the peak of °. 1 Amorphous birefringence Δn8 was determined by the following formula.

Δn=X・ΔnC+ (1-x), Δn3Δnc-fc
・Δnc1 Here, Δn is the average birefringence X determined by an interference microscope. The crystallinity ρC-ρa is determined by the density method using the following formula. Δn is the crystal part birefringence Δnc1 is the ultimate birefringence of PET. It was set to 0.212.

(d) Elongation recovery rate Using a Tensilon tensile tester manufactured by Toyo Baldwin,
The initial length was 2 Q cm, the stretching speed was 2 cm, and the stretching was repeated 5 times at 2% of the original length, and the recovery rate was calculated as 100% when the original length was restored. In this measurement, if the recovery rate is 90% or more, it can be said to be good.

(E) During spinning and winding of the spinning stable polyester yarn, spin and wind it for 30 minutes, and check the following 4 conditions for yarn breakage and continuous winding.
Divided into stages.

◎; Can be continuously wound for 30 minutes without thread breakage.

○: Occasionally, single yarn breaks, but continuous winding is possible for 30 minutes.

△: Continuous winding for several minutes to several minutes is possible.

×: Unable to wind due to thread breakage.

(to) Neck deformation magnification Zimmer outer diameter measuring device model 460
Type A/2 was used to measure the fiber diameter along the spinning line.

The diameter immediately before neck generation is Dl, the diameter immediately after neck generation is D2, and the neck deformation magnification is expressed by the following formula.

Polyester consisting essentially of polyethylene terephthalate with an intrinsic viscosity [η) of 0.63 was made of polyester having an outer diameter of 651 mφ and
Extrusion was carried out at a spinning temperature of 310° C. using a spinneret having a spinning hole diameter of 0.35 mmφ and 24 holes. Immediately below the spinneret, a heating zone was provided in which a circular heating cylinder with an inner diameter of 12 cm and a length of 75 cm was heated by a cast aluminum heater in close contact with the surface of the spinneret, and the temperature of the heating zone was set at 290°C. The yarn that has left the heating area is heated to 20℃1 using a normal side-blowing chamber.
After being cooled by cooling air at 0.1 m/sec to cause neck deformation, it was bundled, oiled, and wound up on a winder without stretching. The yarn after winding was 50'/24.
'.

Table 1 shows the neck deformation ratio during spinning, spinning stability, and each characteristic of the obtained yarn.

As a comparative example, L5 was used as a conventional low speed spun-drawn yarn.
Each characteristic of a polyester yarn drawn 3.3 times after spinning at 00 m for 7 minutes is shown.

As is clear from Table 1, in the method of the present invention, heat resistance,
It can be seen that polyester yarn with excellent stretch recovery properties can be stably obtained.

The following margins are blank: 1. Spinning and winding were carried out in the same manner as in Example 1, except that the spinning speed was 10,000 m/min and the heating cylinder temperature was varied as shown in Table 2. Table 2 shows the neck deformation ratio, spinnability, and properties of the obtained polyester yarn under each temperature condition.

As is clear from Table 2, if the temperature of the heating region is within the range of the present invention, a polyester yarn with good spinnability, high melting point and excellent stretch recovery properties can be obtained. In particular, when used as a raised yarn for a raised fabric, there is no denting during the processing process and it exhibits good surface properties.

Further, according to the production method of the present invention, it is possible to stably produce the polyester yarn without breakage during spinning, and extremely high productivity can be achieved.

[Brief explanation of the drawing]

FIG. 1 illustrates the relationship between the specific surface area of a single yarn and the neck deformation magnification. In the figure, the present invention is shown in a diagonally shaded area surrounded by straight line A and straight line B. Figure 1

Claims (1)

[Claims] 1. The differential scanning calorimeter DSC melting peak temperature is 275°C or higher, the amorphous birefringence (Δn_a) is 0.03 or lower, and the birefringence difference (δΔn) in the filament cross section is 0.0
4 or less, when spinning polyester consisting essentially of polyethylene terephthalate at a speed of 9,000 m/min or more, a heating zone of 250° C. or more is provided immediately below the spinneret to perform heating. , an ultra-high speed spinning method for polyester yarn, characterized in that the neck deformation ratio of the yarn generated during the spinning process is spun within the range shown by the following formula: 3×10^-^3S-0.5≦N≦15× 10^-^3
S-5.5 However, N≧2 (Here, N is the neck deformation magnification, S is the specific surface area of the single yarn cm^2/g)