KR100233301B1 - Manufacture method of polyester fiber - Google Patents

Abstract

The present invention relates to a method for producing a polyester fiber widely used as a reinforcing material for rubber composite materials such as tires, belts, and the like, in particular, stretching stability by a method of instantaneous heating using a high-temperature fluid in the drawing area. It relates to a method of manufacturing high strength industrial yarn by improving the.

Description

[Name of invention]

Method for producing polyester fiber

Detailed description of the invention

The present invention relates to a method for producing a polyester fiber widely used as a reinforcing material for rubber composite materials such as tires, belts, and the like, in particular, stretching stability by a method of instantaneous heating using a high-temperature fluid in the drawing area. It relates to a method of manufacturing high strength industrial yarn by improving the.

Although much effort has been made to produce fibers with high strength, there are limitations in making high strength fibers, which result in continuous filament filament (single cutting) during high magnification stretching for high strength. This is because it is difficult to wound, and in the properties of the obtained yarn due to the damage of the yarn occurs a problem that the strong deterioration and poor shape stability during post-processing such as twisted yarn and heat treatment.

In particular, in the high-speed spinning process, which is currently applied to improve the productivity of the yarn and the stability of the yarn's physical properties, it is higher than the undrawn yarn obtained at low spinning due to the increase in molecular chain orientation of the yarn during high-speed spinning, which is one of the main characteristics of the polymer. The degree of orientation is shown. In the case of such high-speed spinning yarns, the initial high molecular chain orientation causes a limitation in the development of high strength due to the high magnification in the stretching process, making it unsuitable as a reinforcing material for rubber composite materials such as tires and belts.

In order to alleviate the drawbacks caused by the lowering of the stretchability, there have been methods of stretching by high temperature stretching with a hot plate, and improving the stretchability by two step stretching of spinning yarns. Currently, four steps of spinning and stretching are performed in one step. In the multi-stage stretching and heat setting using a six-stage stretching roller in the manufacturing method of the yarn is used.

However, at this time, the difference in drawing point occurs due to the difference in heat transfer between the yarns, so that the cross-sectional uniformity of the yarns is lowered and the operability is degraded due to cutting due to stretching irregularity.

In general, the roller temperature in the drawing area is about 40 ~ 90 ℃, which raises the temperature of the yarn above the glass transition temperature. At this time, there is a time difference of heat transfer to each single yarn, and the drawing point is changed by this phenomenon. The problem of fusion on the surface of the roller occurs, making operation impossible.

Conventionally, in order to solve this drawback, there has been a method of using a drawing pin made of a ceramic type (US Patent No. 2,289,232) or using a high temperature roller serving as a drawing pin (Korean Patent Application No. 92-24981). It was difficult to apply because of the fact that high quality yarns were produced or the operationability was lowered due to the occurrence of high shear and friction due to the friction between the drawing pins and the yarns due to high speed stretching. It is possible to solve the tension problem to some extent by using a high temperature roller. However, maintaining the surface temperature of the roller uniformly and maintaining the temperature at high temperature is not only difficult, but also the manufacturing cost of the roller is high and the contact angle with the roller There were many problems such as the need to change the apostles.

In addition, the conventional polyester yarn is stretched to express high strength, and thus has a high crystal orientation and at the same time the amorphous portion also has a high degree of birefringence, thereby exhibiting a low shrinkage rate.

In order to solve this problem, the present invention improves the elongation by fixing the drawing point by heating the yarn instantaneously using a heating fluid, and lowers the non-orientation, long period, and crystallinity to an appropriate range, and the crystal orientation is as high as conventional. Its purpose is to produce polyester yarns having strength and durability and at the same time having low shrinkage rates by maintaining at a level and expressing low dry heat shrinkage rates.

Hereinafter, the present invention will be described in detail.

The present invention stretches at high magnification after spinning to increase the degree of orientation to directly draw polyester fibers, and between the first and second stage rollers and the second and third stage rollers in which preliminary and major stretching are performed. The present invention relates to improving the drawability and strength by stably fixing the drawing point by installing a slit type jet nozzle capable of controlling temperature.

In the case of stretching using the stretching equipment manufactured according to the present invention, at the time of preliminary stretching, a slight stretching ratio of 1.01 to 1.03 times is given to the unstretched yarn, and the molecule is supplied under the supply of heated air at a temperature of 50 to 100 ° C. or higher than the glass transition temperature. The activation energy should be given to the chain, but at the same time to prevent the folding of the molecular chain and at the same time to give the tension to prevent the tension of the molecular chain.

Generally, the glass transition temperature of polyester is 75-80 degreeC.

The stretching point treatment in the preliminary stretching is not to give the actual stretching point, but to activate the amorphous molecular chain to be flexible in order to facilitate the stretching in the main stretching. The preliminary stretching point treatment allows to have a low amorphous orientation and long period even after the main stretching treatment.

The reason for supplying the heating air to the preliminary stretching portion is that, when the heating steam is supplied to the preliminary stretching portion, which is relatively low temperature compared to the main stretching portion, the stretching nonuniformity is caused by the influence of the temperature nonuniformity.

In the preliminary stretching point treatment, when the treatment temperature is too low or the stretching tension is too high, the activity of the amorphous molecular chain is insufficient, so that it cannot have low non-orientation and the long period becomes large.

On the other hand, if the treatment temperature is too high or the stretching force is small, the activity of the amorphous molecular chain is increased, the folding of the molecular chain (Recoiling) occurs, there is a problem that the strength is lowered as well as the stretchability.

In the main drawing, the necking part can maximize the unfolding flexibility of the molecular chain by applying a draw ratio of 2.0 times higher and a thermal energy of 100 to 250 ° C higher than the glass transition temperature under the supply of a heating steam.

If the temperature of the feed fluid of the drawing point fixing device in the main drawing is too high or the drawing magnification is too low, it is possible to give the external high activation energy to the unstretched and pre-stretched molecular chains rather than spreading the molecular chains by stretching tension. Due to excessive recoiling of the molecular chains, there is a subsequent deterioration of the elongation, and when the stretching is performed at a low temperature, it is affected by the forced stretching due to insufficient molecular chain activation energy for the molecular chains in the folded state. Since it causes death, it is impossible to manufacture the high-strength industrial polyester fiber required by the invention.

The polyester fiber produced according to the present invention has a strength of 8.5 g / d or more, dry heat shrinkage (177 ° C. × 5 minutes) of 3% or less, birefringence of 0.15 to 0.20, nonorientation index of 0.45 to 0.55, and a long period of 120 to 160 kPa. It has physical properties.

If the long or non-orientation is large, the dry heat shrinkage rate is high, and if the non-orientation or the long-orientation is too small, the molecular chain is forcibly stretched while the molecular chain is folded to show high strength.

The long period value represents the size of the crystal and the non-crystal, and a large long period value under the same crystal size indicates a high state of non-orientation. In this state, the shrinkage stress of the non-government is high, resulting in a high dry heat shrinkage rate. Elongation worsens due to the collapsed chains, which leads to elongation that is caused by trimming due to forcible stretching of the molecular chains.

Hereinafter, the present invention will be described in more detail with reference to Examples and Comparative Examples, but the present invention is not limited to the Examples.

Physical properties measurement method of the manufactured yarn in the Example is as follows.

⊙ Birefringence (△ n): A berek compensator was attached to the polarizing microscope and measured by retardation obtained from the indirect chromaticity of the sample.

Δn = R / d

(d: thickness of sample (nm), R: delay time (retardation (nm))

Non-orientational function (fa)

Δn: birefringence

Xc: crystallinity

fc: decision orientation function

Δn _c : intrinsic birefringence of the crystal (0.220)

Δn _a : non-specific intrinsic birefringence (0.275)

Crystal orientation function (fc): The crystal orientation function (fc) is obtained by averaging the respective orientation functions obtained from the half width (X _hkℓ ) in the azimuth diffraction patterns of the (010) plane and the (100) plane by the following equation. .

⊙ Long period (Å): Using an incineration X-ray scattering apparatus from RIGAKU Co., Ltd., which uses a Cuka line with a wavelength of 1.54 Å, a UV indirect diffraction line was obtained under Bragg's equation under a voltage of 50 kV and a current of 200 mÅ.

⊙ Strength, elongation: It was measured using JIS-L1017 method.

Tensile Testing Machine: Low Speed Extension Type

Tensile Speed: 300 mm / min

Sample length: 250mm

Atmosphere temperature: 25 ℃, 65% RH

⊙ Dry heat shrinkage rate (△ S): After leaving the sample in 25 ℃, 65% RH for 24 hours, measure the length of the sample measured under 20g L _o , and in the oven after standing at 177 ℃ × 5 minutes under no load. One length was taken as L <_1> and it calculated | required by the following formula.

[Examples and Comparative Examples]

In the present invention, the jet nozzle may use a nozzle having a distance of 2 to 10 mm and an injection angle of 10 to 60 °. In an embodiment, the blow nozzle is blown among the Unijet type of Spray System Co., Ltd. A blow-off nozzle type was used, and the heating fluid was uniformly supplied at a pressure of 2 kg · f / cm 2, respectively, in the preliminary stretching section with heating air and in the main stretching section with heating steam. The reason for supplying the heating air to the preliminary stretching portion is that, when the heating steam is supplied to the preliminary stretching portion, which is relatively low temperature compared to the main stretching portion, the stretching nonuniformity is caused by the influence of the temperature nonuniformity.

In this embodiment, the melt viscosity is 0.98 using a polyester chip having an absolute viscosity of 0.98, a melt viscosity of 25,000, and a glass transition temperature of 80 ° C., and the spinning speed is 3,500 m / min, stretching two stages, one stage heat setting, and two. However, 100 denier and 250 filament yarns were manufactured by applying the fruit-use-type drawing point fixing device of the present invention to the first and second stage drawing units in the process of manufacturing yarns by applying the relaxation process.

The conditions of the examples and the physical properties of the prepared stretched yarn are shown in Table 1 below.

TABLE 1

TABLE 1a

In view of the above results, it was difficult to wind up when the application of the present invention exceeds the range, in particular, in the case of low temperature it is difficult to fix the draw point by heating the temperature of the yarn instantaneously, the cutting.

Claims (2)

A polyester fiber having an intensity of 8.5 g / d or more, a dry heat shrinkage (177 ° C. for 5 minutes) of 3% or less, a birefringence of 0.15 to 0.20, a non-orientation index of 0.45 to 0.55, and a long period of 120 to 160 kPa. In manufacturing polyester fiber by melt spinning and stretching a polyester having polyethylene terephthalate as the main repeating unit, the stretching process is performed by 1.01 to 10.3 times under the supply of heated air from the preliminary stretching section to increase the temperature of the stretching point fixing device. A polyester having a temperature of Tg + 50 ° C. to Tg + 100 ° C., which is stretched 2.0 to 3.0 times under the supply of heating steam from the main stretching part, and the temperature of the drawing point fixing device is Tg + 100 ° C. to Tg + 250 ° C. Method of making fibers (where Tg is the glass transition temperature of polyester).