JPH02269807A - Polyester multifilament and production thereof - Google Patents

Abstract

PURPOSE:To obtain the subject fiber capable of developing fine crimps by heat treatment and having excellent processability by cooling a polyester filament extruded through a nozzle with air, asymmetrically cooling the air-cooled filament with an aqueous liquid applied to the filament in a region in which the filament is cooled at a specific temperature and finally taking up the filament at a high speed. CONSTITUTION:In the melt spinning of a polyester, a polyester filament extruded through a nozzle is cooled with air and then asymmetrically cooled with an aqueous liquid applied to the filament in a region in which the filament is cooled to 250-150 deg.C. The cooled filament is taken up at a spinning speed of >=5,000m/min, preferably 5,000-7,500m/min to obtain the objective filament. The filament is a non-sensible crimped filament capable of developing the crimps by later heat-treatment and having the following characteristics. The crystallinity determined by wide-angle X-ray diffraction is <=50%, preferably 25-40%, the difference of birefringence of the cross-section of the filament between the outer layer and the inner layer is 20X10<-3>-100X10<-3> and the distribution of the inner layer is eccentric from the center of the filament.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a novel polyester multifilament and a method for producing the same. More specifically, the present invention relates to a polyester multifilament that has good processability and can develop fine crimp through heat treatment, and a manufacturing method for obtaining the same by high-speed spinning.

[Prior Art and Problems to be Solved by the Invention] Polyester crimped yarns are widely used for mixed fiber blending purposes, bulky fabrics, and the like.

On the other hand, when polyester is spun at high speed, molecular orientation and crystallization increase with increasing spinning speed, and the spinning speed is approximately 50%.
Fibers obtained at speeds exceeding 00 m/min are produced by conventional low-speed spinning.
It is known that it exhibits sufficient mechanical properties comparable to drawn yarn and can be used for knitted fabrics, raised fabrics, etc. without being drawn.

In recent years, attempts have been made to obtain crimped yarns at low cost using such high-speed spinning methods.

Japanese Unexamined Patent Publication No. 55-107511, Journal of the Fiber Science Society Vol. 1.
37°Na4 (1981) T-135~T-142
As a result of partial cooling using quenched air during high-speed spinning at a spinning speed of 8,000 m/min or more, a birefringent index has a difference between the outer layer and the inner layer within the cross section of the filament, and the birefringence has a distribution eccentric from the center of the filament. It has been shown that the as-spun fibers exhibit weak apparent crimp. However, the actual crimped fibers obtained according to this publication are wide-angle
Since the fiber has a high crystallinity with a crystallinity X'c determined by a linear diffraction method of about 60% or more, there is almost no shrinkage of the fibers even after subsequent heat treatment, so the degree of crimp does not increase. Therefore, the fabric obtained by knitting and weaving the fibers obtained according to the publication did not exhibit bulkiness at all. Rather,
Due to the apparent weak helical crimp, the filament has poor convergence during processing such as knitting and weaving, resulting in problems such as processing defects.

JP-A-62-23816 discloses a spinning speed of 6,000 m.
It has been shown that in high-speed spinning of 1/min or more, clearly crimped fibers can be obtained by cooling the vicinity of the thinning end point of the ejected filament with a liquid.

However, even according to this publication, the actual crimp does not increase with subsequent heat treatment, and not only is it impossible to obtain a bulky fabric, but also the helical crimp becomes apparent, resulting in a problem of deterioration in processability. there were.

Therefore, the polyester mulch can be manufactured at high speed and at low cost, and is essentially a non-crimpable filament until it goes through the processing process, and can develop fine crimp and bulkiness through heat treatment after being made into a fabric. The advent of filaments and methods of manufacturing them has been highly desired.

In view of the above-mentioned problems, the object of the present invention is to provide a polyester multifilament that is substantially non-crimpable until undergoing processing steps such as knitting and weaving, and that becomes crimped and bulky through subsequent heat treatment. The object of the present invention is to provide a method for easily and inexpensively manufacturing the multifilament.

[Means to solve the problem]

The object of the present invention is that the degree of crystallinity determined by wide-angle X-ray diffraction is 50% or less, and the birefringence of the cross section of the filament is 20X10-'~too x
It is a non-obviously crimped filament that has a difference in to-' and a distribution eccentric from the filament center, and is achieved with a polyester multifilament that can be crimped by subsequent heat treatment. A preferred method for producing the polyester multifilament of the present invention is to air-cool the filaments extruded from the spinneret when melt-spinning the polyester, so that the temperature of the filaments is between 250°C and 100°C.
This is a method for producing a polyester multifilament, which comprises applying an aqueous liquid in a zone to be cooled to 50° C. for asymmetric cooling, and then taking it off at a spinning speed of 5,000 m/min or more.

The polyester used in the present invention is a polyester consisting essentially of ethylene terephthalate containing 90 mol % or more, preferably 95 mol % or more of ethylene terephthalate repeating units, but within a range that does not impair thermal and mechanical stability. It may also contain a small amount of a third component.

The polyester multifilament of the present invention needs to have a degree of crystallinity of 50% or less as determined by wide-angle X-ray diffraction measured by the method described below.

If the crystallinity exceeds 50%, the thermal stability will be good, but the fresh water shrinkage will be as small as about 5% or less. In such a low-shrinkage filament, the preferred crystallinity that provides sufficient bulk when the birefringence distribution in the cross-section of the filament is expanded and does not cause excessive shrinkage is as follows:
It is about 25% to 40%. Therefore, the fresh water shrinkage rate is 5 to 40%, preferably 10% to 30%.

The multifilament of the present invention has not only the crystallinity but also a birefringence of 20X in the outer layer and inner layer of each filament cross section.
It is necessary to have a difference of 10-' to too X 10-' and a distribution eccentric from the filament center. The birefringence distribution within the cross section of the filament is measured by the method described below using a differential interference microscope. Here, the outer layer of the filament cross section refers to a position 0.9 H from the center, where R is the radius of the filament. Furthermore, the inner layer refers to the position of the lowest birefringence in the cross section of the filament.

This inner layer with the lowest birefringence is offset by X from the geometric center of the filament cross section. Therefore, the eccentricity ratio can be quantitatively measured as x/R.

After the multifilament of the present invention is made into a fabric, in order to obtain sufficient bulk by heat treatment, the birefringence difference δ (Δn) between the inner and outer layers is 20X10-'' to 100XIO-', preferably 30X10-'' to 100 X 10-3. Also, x/R is greater than 0.05, preferably 0.
This is achieved by having one or more of the following.

When δ(Δn) is less than 20XlO-'' or when the eccentricity ratio x/R of the birefringence distribution is less than 0.05, the bulkiness of the fabric is insufficient.

Although the single filament denier of the filaments constituting the multifilament of the present invention is not particularly limited, when used for clothing, a single filament denier of 1 to 5 is preferable.

Due to this special microstructure, the multifilament of the present invention develops fine crimps through heat treatment. The form of the crimp is a non-helical crimp.

FIG. 1 shows a microscopic photograph of the multifilament of the present invention after the multifilament was treated with clean water at 95° C. to develop crimp. As is clear from FIG. 1, it is a fine crimp having several to ten or more bends per 1 + nm unit length. The development of such fine crimp gives the knitted fabric a bulky and soft texture.

Furthermore, the polyester multifilament of the present invention exhibits a relatively low modulus compared to filaments obtained by known high-speed spinning, and has a high fresh water shrinkage rate, so the fabric after heat treatment is extremely soft. Another major feature is that it gives texture.

Hereinafter, the method for producing polyester multifilament of the present invention will be explained.

In the manufacturing method of the present invention, when polyester is melt-spun, the filament extruded from the spinneret is air-cooled, and before the filament temperature reaches 150'C or less, an aqueous liquid is applied to the filament for asymmetric cooling, and then, Spinning speed 5000m
This is a method for producing polyester multifilament, characterized in that the polyester multifilament is drawn off in a time of 1 minute or more. More preferably, the filaments extruded from the spinneret are air-cooled, the filaments are bundled in an area where the temperature of the filaments is cooled to 250°C to 150°C, and the bundler is used to reduce the filaments to 20 to 500% by weight (filament weight). This is a method for producing a polyester multifilament, which is characterized by applying an aqueous liquid (per), asymmetrically cooling it, and taking it off at a spinning speed of 5,000 to 7,500 m/min.

FIG. 2 shows a schematic diagram of spinning equipment for carrying out the manufacturing method of the present invention.

In FIG. 2, polyester is extruded as filaments from a spinneret 2 attached to a spinning head 1'1. The filament 4 exiting the heating cylinder 3 provided under the spinneret is cooled by the cooling air from the cooling air chamber 7, and is asymmetrically cooled by the aqueous liquid application nozzle 5. Next, after applying a lubricant using the oil supply nozzle 6, the package 8 is wound up by a winding machine.

In the manufacturing method of the present invention, the spinning speed is 5000 m7
It must be at least 1 minute. Below 5000 m/min, the large birefringence difference δ (Δn
) cannot be obtained.

y, when the spinning speed is less than 5000 m/min, the elongation of the filament is as high as about 80% or more, and for example, tensile stress received in post-processing processes such as knitting and weaving easily causes elongation, resulting in defects such as unevenness. , it is difficult to put it into practical use as it is.

The spinning speed of the present invention is 5000 m/min to 8000 m
/min, the object of the present invention is effectively achieved. Even if the spinning speed is about 8000 m/min or higher, it is possible to obtain the multifilament of the present invention by applying a very large amount of aqueous liquid, but it is possible to obtain the multifilament of the present invention by adding a large amount of aqueous liquid to adjust the crystallinity of the filament. Application is required, and problems such as scattering of the aqueous liquid occur.

In view of the mechanical properties and structure formation of the filaments, the most preferred spinning speed is 5500 to 7500 m/min.

Textile Society Journal Vol. 1.37. Na 4 (1981) T
-135 to T-142, the development of cross-sectional non-uniform structure occurs only at spinning speeds of about 8,000 m/min or higher, which is significantly different.

Within the speed range of the present invention, the process can be carried out stably and industrially without problems such as a significant increase in spinning tension or yarn breakage during spinning.

In the present invention, the filament extruded from the spinneret is air-cooled,
Before the filament temperature reaches 150°C or less,
More specifically, it is characterized by asymmetric cooling by applying an aqueous liquid to the area to be cooled to 250°C to 150°C.

By asymmetrically cooling the filament with an aqueous liquid at such a high temperature, the crystallinity and eccentric birefringence distribution characteristic of the filament of the present invention are exhibited.

If the filament temperature when applying the aqueous liquid is less than 150°C, the object of the present invention will not be achieved no matter how the conditions such as the amount of applied water are selected.

The higher the filament temperature is than 150°C when applying the aqueous liquid, the larger the birefringence difference δ (Δn) becomes.
If the temperature exceeds about 250°C, problems such as thread breakage occur when applying an aqueous liquid. Therefore, the preferred filament temperature is 150-250°C.

Generally, in melt spinning polyester, the polyester is extruded from a spinneret at 280-320°C.

In the method of the present invention, cooling of the filament before application of the aqueous liquid is achieved by cooling with cooling air commonly employed in melt spinning. The position from the spinneret surface where the filament temperature is preferably 150°C or higher for carrying out the present invention varies depending on the spinning speed and the denier of the filament, but the position at which the filament temperature is 5QOOm/min or higher and is usually used for clothing is different depending on the spinning speed and filament denier. If it is 1 to 5 denier, it is about 8 below the spinneret.
It is within 0 cm. Therefore, the application of the aqueous liquid of the present invention is carried out during this period. It is known that when the spinning speed exceeds about 6000 m/min, a phenomenon in the yarn diameter and severe thinning deformation are observed during the spinning process (Journal of the Japan Textile Society, Vol. 38).
, N1111 (1982) P, 499-P, 507)
. The application position of the aqueous liquid of the present invention is about 5 cm or more above the deformation position, more preferably about 10 cm or more above the thinning deformation position (neck point). For example, when the filament denier is 3 denier and is spun at a spinning speed of 6000 m/min, and the thinning deformation position is 70cI11 below the spinneret surface, the aqueous liquid is applied within 65c+++ below the spinneret surface, preferably 60ca+ Granted within.

As the aqueous liquid used for cooling the filaments in the present invention, water, a usual oil emulsion for spinning, etc. can be used. Water is conveniently used. Further, although the temperature of the aqueous liquid is preferably lower, the present invention can be achieved even without cooling the aqueous liquid below room temperature.

The method for applying the aqueous liquid may be selected from the roll method, nozzle method, wet wall method, etc. which are normally used for applying spinning oil, but other methods may be used as long as the purpose of the present invention is not impaired. Recruitment is also possible. From the viewpoint of quantitative property of aqueous liquid application, a nozzle system as shown in FIG. 3 is desirable.

The amount of aqueous liquid applied to the filament is expressed in weight basis I· with respect to the filament. In the present invention, the larger the amount of water applied, the more it is possible to reduce the degree of crystallinity even at the same filament temperature. The objects of the present invention are achieved if the amount of water applied is about 20 weight percent or more. When the amount of water reaches 500 weight percent,
It is necessary to prevent excess aqueous liquid from scattering.

In the present invention, the number of filaments I when applying the aqueous liquid is:
Either a method of applying the adhesive to each filament or a method of applying a plurality of filaments at the same time may be used. When applying a plurality of filaments in a bundle, since the filaments are at a high temperature of 150° C. or more, they tend to fuse together and cause problems such as thread breakage. In the present invention, it is a surprising discovery that by setting the amount of water applied to be about 50% by weight or more, the above-mentioned fusion phenomenon can be completely solved and extremely stable spinning can be achieved.

The preferred amount of water applied is 20 to 300 weight percent.

Specifically, when applying an aqueous liquid using a nozzle method as shown in Fig. 3, multiple filaments l- as shown in Fig. 4 are applied.
This is achieved by focusing and simultaneously applying an aqueous liquid at the focusing section. Even when the number of filaments is 3 to 20, there is no single filament adhesion, and good spinning stability can be achieved.

〔Example〕

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

Incidentally, each characteristic used in the Examples was measured by the following method.

0 Crystallinity Using an X-ray diffraction device, the thickness of the sample was determined to be approximately 0.511IIn.
Jif is the diffraction intensity curve with a diffraction angle 2θ from 7° to 35° in the equator direction with respect to the fiber axis of the sample under the following conditions.
There was f.

The conditions were 30 KV, somE, scanning speed p/min, chart speed 10 mm/min, time constant I-1 second, and receiving slit 0.3 mm.

The three main reflections drawn in the range of 2θ-17° to 26° from the low angle side are (100), (010), (
110).

The diffraction intensity curves between 2θ-7° and 35° are connected with a straight line and used as a baseline.

As shown in FIG. 5, the valley around 2θ=20° is set as the apex, connected with a straight line along the base of the low angle side and the high angle side, separated into a crystalline portion and an amorphous portion, and determined by the area method according to the following formula.

O birefringence distribution A transmission quantitative interference microscope manufactured by Karl Zeiss Jena, East Germany was used to measure the refractive index n // for light vibrating parallel to the fiber axis and the refractive index n // for light vibrating parallel to the fiber axis using green light (wavelength 549 mμ). The birefringence Δn is expressed as Δn−n1l n from the value of the refractive index n for the light.

When the single fiber cross section was circular, 7-shaped or U-shaped interference fringes were observed, and the birefringence distribution in the radial direction of the single fiber cross section was determined from the interference fringes. The average birefringence (Δ-n) was determined from the volume average value.

○ Fresh water shrinkage rate A load of O, 1 g/d was applied to the fiber, and the length was measured.

Next, after performing boiling water treatment at 98°C for 5 minutes with no load,
After drying for a day and night below 40°C, 0.1g/d is applied to the fiber again.
A load was applied and the length was measured.

The fresh water shrinkage rate is expressed by the following formula.

L+ 0 Strength/Elongation THNSILON UTM-I manufactured by Toyo Baldwin
The initial length was 20 cm (however,
The crimp was measured (length after stretching) at a stretching speed of 20 cm/min.

0 Bulky The obtained multifilament was woven into a tubular knitted fabric, and the thickness of the knitted fabric was measured. Next, this knitted fabric was subjected to a clean water treatment in 98°C1 boiling water for 5 minutes, and then the thickness was measured. The bulkiness was expressed as the increase rate (%) in the thickness of the knitted fabric using the following formula.

If the increase rate is 5% or more, the bulkiness is considered to be good.

0 Hand: The tubular knitted fabric after the water conduction treatment for bulkiness measurement described above was evaluated in three stages by sensitivity testing.

3: Very soft (pass) 2: Medium soft (pass) l:
Hard (fail) 0 Filament temperature Filament temperature was measured non-contact along spinning line -F using a scanning infrared thermometer.

Polyethylene terephthalate having an intrinsic viscosity [η) of 0.62 on thornstone was spun using a spinning machine shown in FIG. 2 using a spinneret having a hole diameter of 0.35 nuaφ and a number of holes of 24. Spinning temperature 3
00°C, and under the spinneret there is an inner diameter of 12cm and a length of 25C1.
A heating cylinder with an aluminum cast heater heating method was installed with no gap between the spinneret surface and the cylinder, and the heater temperature was set at 250°C.
The temperature was adjusted to ℃.

The filament exiting the heating tube is cooled by cooling air at a temperature of 20°C and a wind speed of 0.30 m/sec in a side-blowing cooling air chamber, and then heated by two nozzles using the method shown in Figure 4. Asymmetric cooling was performed by applying 80 weight percent room temperature water per yarn weight while focusing 12 filaments per nozzle. The position of asymmetric cooling by water application was 50 cm below the cut. The yarn temperature at this position is approximately 180' in this spinning speed range, as shown in Table 1.
The temperature was between 190°C and 190°C.

The asymmetrically cooled filaments were coated with an oil agent and then wound to a speed of 50 d/24 f without being drawn and wound at different spinning speeds as shown in Table 1.

Table 1 shows the properties of the obtained multifilament.

In addition, the position of the neck point under the cut during spinning shown in Table 1 is as follows:
This is the value measured when no water was added. Measurement is Z
Measurement was performed using a wire diameter measuring instrument 4 manufactured by IMMHR (Model 3OA/2) and visual observation, and both were in good agreement.

As is clear from Table 1, fabrics having excellent bulk and flexibility were obtained from the polyester multifilament of the present invention.

Although No. 1 (comparative example) in Table 1 had excellent bulkiness, the cloth had a soft texture due to its high fresh water shrinkage rate.

In order to obtain 50 d/24 f in the same manner as in Example 1, the spinning speed was kept constant at 6,000 m/min, and the position of asymmetric cooling by water application was varied as shown in Table 2.

The properties of the obtained multifilament are shown in Table 2.

As is clear from Table 2, the multifilament of the Urine invention obtained by asymmetric cooling at a yarn temperature of 150° C. or higher yields a fabric with excellent bulk and soft feel.

In the same manner as in Example 1, the position of asymmetric cooling by water application was kept constant at 48 cm below the spinneret (yarn temperature 180"C), and the amount of water application was varied as shown in Table 3. speed 620
A multifilament of 50 d/24 f was obtained at 0 m/min.

Table 3 shows the properties of the obtained multifilament.

〔Effect of the invention〕

When the polyester multifilament of the present invention is used in knitted textiles, processing can be performed without trouble during knitting and weaving, and
The subsequent heat treatment gives the fabric a soft texture and bulk. When used in fields such as women's clothing and raised fabrics, these characteristics result in fabrics that have an extremely luxurious feel and exhibit excellent performance.

In addition, the production method of the present invention can produce the multifilament at high speed and simply without any trouble during spinning, so it has high productivity and has extremely high industrial value.

[Brief explanation of drawings]

Fig. 1 is a micrograph showing the shape of the fiber after the filament of the present invention has been subjected to water-conducting treatment, Fig. 2 is a schematic front view of a spinning machine implementing the present invention, and Fig. 3 is an asymmetrical FIG. 4 is a schematic front view of the nozzle used for cooling; FIG. 4 is a perspective view showing how a plurality of filaments are bundled and an aqueous liquid is applied at the same time; FIG. 5 is a diagram showing the degree of crystallinity of the fiber of the present invention. It is a figure which shows an example of the X-ray diffraction intensity curve in measurement. ... spin head, ... heating tube, ... aqueous liquid application nozzle, ... cooling air chamber 2 ... spinneret, 4 ... filament, 6 ... oil supply nozzle, 8 ... Pancake.

Claims (1)

[Claims] 1. Crystallinity determined by wide-angle X-ray diffraction method is 50
% or less, the birefringence of the filament cross section has a difference of 20 x 10^-^3 to 100 x 10^-^3 between the outer layer and the inner layer, and has a distribution eccentric from the filament center. A polyester multifilament that is a crimped filament and can be crimped by subsequent heat treatment. 2. When melt-spinning polyester, the filaments extruded from the spinneret are air-cooled, and the temperature of the filaments is 2.
A method for producing a polyester multifilament, which comprises applying an aqueous liquid in a region cooled to 50° C. to 150° C., performing asymmetric cooling, and taking off at a spinning speed of 5,000 m/min or more.