JPH01314719A - Naturally crimpable polyamide multifilament yarn - Google Patents

Abstract

PURPOSE:To obtain the subject low-cost filament, having asymmetric thermal properties in the radial direction of the single filaments, capable of producing crimps with performance similar to that of mechanically processed crimped polyamide yarn and suitable as socks or stockings. CONSTITUTION:The objective polyamide multifilament yarn, having interference fringes of single filaments in a polyamide multifilament yarn of a circular cross section observed as asymmetric relatively to the central axis of the above- mentioned single filaments measured by a transmitting type interference microscope and >=80% crystal orientation degree measured by a wide angle X-ray diffractometry and capable of producing crimps by heat treatment.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] The present invention relates to a polyamide multifilament capable of exhibiting natural crimp. More specifically, it is a polyamide mulch that can develop crimps due to the radially asymmetric thermal properties of single yarns, rather than crimps obtained by mechanical processing such as false twisting. Concerning filaments.

[Conventional technology]

By mechanical processing methods such as false twisting and pressing, polyamide multifilament crimped yarns such as nylon 6 and nylon 66 are produced in large quantities and are widely used in socks, carpets, and the like. However, manufacturing crimped yarn by these mechanical processes requires an expensive processing machine and a large amount of energy and manpower. Therefore, the cost of the crimped yarn becomes extremely high.

On the other hand, nylon 66 is disclosed in Japanese Patent Application Laid-open No. 57-154409
It is disclosed that a multifilament single yarn obtained by high-speed spinning of 8,000 m/min or higher has a birefringence distribution in the radial direction. However, in this high-speed spun nylon 66 multifilament, the birefringence distribution in the radial direction, that is, the interference fringes observed with a transmission interference microscope, are symmetrical with respect to the central axis of the single filament, and natural crimp does not occur in principle. It is something.

Furthermore, this conventional technique does not mention natural crimp at all.

[Problem to be solved by the invention]

The purpose of the present invention is to provide a polyamide crimped yarn that has performance equivalent to mechanically processed polyamide crimped yarn, can be used for socks and carpets, and is lower in cost than so-called processed yarns. do.

[Means to solve the problem]

As a result of intensive research on high-speed spinning of polyamide, the present inventors discovered that by applying an aqueous liquid to the filament immediately after spinning and rapidly cooling it, crimp occurs due to the subsequent heat treatment, and thus completed the present invention. .

That is, the object of the present invention is to provide a polyamide multifilament consisting of a single yarn with a substantially circular cross-sectional shape, in which interference fringes observed with a transmission interference microscope of the single yarn are asymmetrical with respect to the central axis of the single yarn and wide-angle This is achieved by a naturally crimpable multifilament that has a degree of crystal orientation measured by a line diffraction method of 80% or more and can be crimped by heat treatment.

In the present invention, each single thread of the multifilament has a substantially circular cross-sectional shape. In other words, obviously irregular cross sections are outside the scope of the present invention.

In the present invention, the interference fringes observed with a transmission interference microscope for each single yarn must be asymmetrical with respect to the central axis of the single yarn. A method for observing interference fringes using a transmission interference microscope will be described later. Interference fringes are U-shaped or 7-shaped fringes shown in FIGS. 1(a) and 1(b), and these fringes reflect the radial distribution of birefringence of a single fiber. The fact that the interference fringes are asymmetrical with respect to the central axis of the single yarn means that the lowest point of the interference fringes is not on the central axis as shown in FIG. 1(a). If the interference fringes are symmetrical about the central axis, not only will the birefringence distribution be symmetrical, but the thermal properties of the single yarn, i.e., the thermal shrinkage rate, will also be symmetrical, making it impossible in principle for natural crimp to occur. . This is because natural crimp occurs due to asymmetry in thermal shrinkage rate. That is, asymmetry of interference fringes is a necessary condition for the expression of natural crimp.

In the present invention, the degree of orientation measured by wide-angle X-ray diffraction must be 80% or more. If it is less than 80%, the average orientation of the multifilaments is insufficient and the strength is so low as to be impractical.

A preferable range of the degree of orientation is 85% or more, and a more preferable range is 90% or more.

In the present invention, the polyamide multifilament must be able to develop natural crimp by heat treatment.

This is because multifilaments suitable for socks, carpets, etc. must have a certain level of bulk, and for that purpose they must be crimped, and in order to reduce costs, crimping must be achieved by a simple method. Must be. In the present invention, "capable of developing crimp" means that crimp can be obtained by boiling hydrothermal treatment with a crimp elongation rate of 10% or more and a crimp elastic modulus of 65% or more. Even if the interference fringes are asymmetric, the purpose of the present invention cannot be achieved unless crimp occurs, and it is necessary for cost reduction to develop crimp by a simple method such as heat treatment. . The degree of crimp produced by heat treatment is preferably such that the crimp elongation rate is 15% or more and the crimp elastic modulus is 70% or more.

The polyamide in the present invention is nylon 66, nylon 6
, nylon 4,6, nylon 12, and other known polyamides, and those obtained by known polymerization methods may be used. From the viewpoint of cost, nylon 66 or nylon 6 is preferred. Further, the polyamide resin may contain additives such as an oil agent, a heat stabilizer, and an antistatic agent.

Next, a method for manufacturing the polyamide multifilament of the present invention will be explained.

Using a known melt spinning machine, molten polyamide is extruded into the atmosphere through a spinneret having a plurality of holes to form filaments, and the multifilament is formed into a multifilament at a high speed of about 4000 m/min or more using a known winding machine. Wind it up. At this time, while each spun filament (single yarn) does not reach 150° C. or lower, an aqueous liquid is applied from one side of the single yarn to cool it while preventing the filaments from coming into contact with each other. As the aqueous liquid, water or an aqueous oil solution used in ordinary spinning is employed.

Water is conveniently used. In this method, it is preferable to apply the aqueous liquid using an oiling nozzle guide or an oiling roll. Natural crimp is developed by heat-treating the wound multifilament in the form of yarn, or by heat-treating it in a dyeing process after making it into a knitted fabric.

〔Example〕

The present invention will be explained in detail with reference to Examples.

The method for measuring the characteristics of the naturally crimpable polyamide multifilament of the present invention will be described below.

(a) Single yarn temperature The single yarn temperature was measured in a non-contact manner along the spinning line using a scanning infrared thermometer.

(b) Crystal orientation degree The degree of crystal orientation of polyamide multifilament can be measured using an X-ray generator (RU-200PL) manufactured by Rigaku Corporation, a fiber sample measuring device (FS-3), and a goniometer (SG-9).
, a scintillation counter is used for the counter, a liquid height analyzer is used for the counting section, and Cu is made monochromatic with a nickel filter.
Measured at line K, (λ-1,5418 people). The X-ray generator operates at 30 kV and 80 mA.

The goniometer is set to the 2θ value of the diffraction peak obtained from the equatorial diffraction curve. Using the symmetric 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 "7 minutes, chart speed 1"
01/min, time constant 1 second, collimator 21
φ, receiving pick-up throat length 1.9m 1% width 3.
It is 5 cranes.

To determine the degree of crystal orientation from the obtained diffraction intensity curve in the azimuthal direction, the average value of the diffraction intensities obtained at +180° is taken, and a horizontal line is drawn to use it as a base line. 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 intersection of this horizontal line and the diffraction fineness 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 the following formula.

(c) Crimping elongation rate and crimp elasticity polyamide multifilament 1- cotton circumference 1.125 m
Using a measuring machine, make a small wind with 20 turns.

The obtained small skein is heat-treated in boiling water at 98° C. for 5 minutes under no load, and then left in a room at a constant temperature of - day and night (IJL degree 20±2° C., relative humidity 65±2%).

A load of 2/d is applied to the humidity-conditioned fibers, and the wind length A is measured after 1 minute. Next, apply a load of 0.1 g/d to the small skein, measure the skein length β2 after 1 minute, immediately remove the load, apply a further load of 2 g/d to the small skein, and measure the skein length β3 after 1 minute. do. The crimp elongation rate and crimp elasticity are expressed by the following equations.

In addition, in consideration of sample variations, measurements were performed using one sample per sample.
Measurements were made at 0 points and the average value is shown.

(d) Observation of interference fringes using a transmission interference microscope Using a transmission quantitative interference microscope manufactured by Karl Zeiss Jena, East Germany, interference fringes having an electric field vector parallel to the fiber axis are observed using green light (wavelength 549 mμ). To determine whether the interference fringes are symmetrical or asymmetrical with respect to the central axis of the fiber, observe the fiber while rotating it in the circumferential direction, and as shown in Figure 1(a), look at the lowest point of the figure 7 or U A letter shape having a portion where an interference fringe pattern is observed where the highest point is not on the central axis of the fiber is determined to be asymmetric.

11-3, 611,2 η was measured by dissolving 1 g/100 cc in 95% sulfuric acid.

Using the melt spinning apparatus shown in FIG. 2, Nylon 66 having a diameter of 2.62 mm was melt spun at 300° C. through a spinneret having four holes of diameter Q, 3111. At this time, the spinning temperature was kept constant at 7000 m/min, the single fiber denier of the multifilament was constant at 14 denier, and room temperature water was applied to each single fiber from one side by a water supply roll. At that time, by changing the height of the water supply roll, that is, the position of the water supply roll from the spinneret, the temperature of the single fiber at the water application position was varied.

Table 1 shows the symmetry and degree of crystal orientation of the interference fringes of the single yarn before heat treatment, and the crimp elongation rate and crimp elasticity after heat treatment.

Comparative Example 1 in Table 1 is essentially air-cooled, and the interference fringes are symmetrical with air cooling, indicating that no natural crimp occurs.

As shown in Examples 1 to 3, excellent crimp can be obtained by cooling the filament while keeping it at a temperature of 150° C. or higher.

Table 1 below: ``Position where water was applied - Distance from the spinneret surface''
Single yarn temperature at the position where water is applied The polyamide multifilament of the present invention is less expensive than conventional processed yarns, so it can be supplied at low cost as crimped yarns for socks, carpets, etc.

Furthermore, products such as socks and carpets obtained from the polyamide multifilament of the present invention are in no way inferior to those obtained from conventional processed yarns.

Furthermore, the polyamide multifilament of the present invention can be canted to form stable fibers, which can be made into spun yarn, futon cotton, or the like.

[Brief explanation of the drawing]

Figure 1 shows an example of filament interference fringes observed by a transmission interference microscope, Figure 1 (a) shows an example of a fiber obtained by the present invention that is asymmetric with respect to its central axis, and Figure 1 (b) shows an example of filament interference fringes.
is an example of symmetry with respect to the central axis of the fiber. FIG. 2 is a schematic front view of an apparatus used for producing the fiber of the present invention. ■...Spin head, 2...Spinneret, 3...
・Filament, 4...Aqueous liquid supply roll, 5...
- Winding section. (a) ' (b) Figure 1, Figure 2, same 109-

Claims (1)

[Claims] In a polyamide multifilament consisting of a single filament with a substantially circular cross-sectional shape, the interference fringes observed with a transmission interference microscope of the single filament are asymmetrical with respect to the central axis of the single filament and measured by wide-angle X-ray diffraction method. A naturally crimpable polyamide multifilament, which has a degree of crystal orientation of 80% or more and can be crimped by heat treatment.