JPS5817293B2 - Polyester Kenshiyukushino Seizouhou - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for producing a crimped yarn by drawing and false twisting an undrawn polyester yarn obtained by high-speed spinning, and the undrawn yarn has unknown changes over time.

The object of the present invention is to accurately divide drawn yarn into lots to produce polyester crimped yarn with excellent quality uniformity, especially level dyeing ability, and crimping performance.

Recently, a method of producing crimped yarns has been implemented by subjecting undrawn polyester yarns obtained by high-speed spinning to simultaneous or sequential stretching and false twisting.

However, even undrawn yarn obtained by high-speed spinning is far inferior in stability over time compared to drawn yarn. Exposure to abnormally high temperatures during storage up to medium or stretched false twisting, or prolonged storage, can lead to changes in the quality of the crimped yarn (mainly dark dyeing during dyeing). (decreased crimp performance)
It causes.

Therefore, it is desirable to detect such changes over time in undrawn yarn before drawing and false twisting, but there is currently no effective means for checking changes over time in undrawn yarn. Currently, it is only discovered after commercialization.

The present inventors have attempted to solve such problems (as a result of repeated research, it is possible to measure the thermogram of undrawn yarn and determine the degree of change over time based on its endothermic peak temperature (Tp),
The present invention was achieved based on the discovery that if the endothermic peak temperature (Tp) is within a specific range, even if the same lot is subjected to stretching and false twisting, unevenness in product quality will not occur.

That is, in the present invention, when producing a crimped yarn by drawing and false twisting an undrawn polyester yarn having a birefringence index (△n) of 0.015 or more, the endothermic peak temperature of the thermogram of the undrawn yarn is determined in advance. (Tp'C), and the endothermic peak temperature ('rp'c) satisfies the condition of 'rp≦400△n+57 with respect to the birefringence index (△n) of undrawn yarn as the same lot. This is a method for producing polychilled crimped yarn with excellent uniformity in quality, particularly in level dyeing properties, by drawing and false twisting.

The polyester used in the present invention refers to polyethylene terephthalate or a substantially linear polyester containing 80 mol% or more, preferably 90 mol% or more of ethylene terephthalate units.

The polyester may contain known additives such as matte colorants, flame retardants, and the like.

In the present invention, it is necessary to use a high-speed spun yarn with a birefringence index (△n) of 0.015 or more as the undrawn polyester yarn to be subjected to the drawing and false twisting process. It is difficult to thread the yarn into a twisting machine, and furthermore, it is undesirable because it has poor durability against changes over time.

According to the present invention, before drawing and false twisting such an undrawn yarn, a part of the undrawn yarn is randomly taken out in advance,
Measure the thermograph and find the endothermic peak temperature (Tp'C:)
Determine the presence or absence of changes over time.

The thermogram referred to in the present invention is a curve obtained by measuring the differential thermal behavior of a sample during temperature rise using a differential thermal analyzer DTA or a differential calorimeter DSC, as shown in FIG. In response to temperature, a change to the endothermic side of the baseline appears around 70°C, but due to changes over time, a small endothermic peak occurs near the glass transition temperature, and as shown in Figure 2, the higher the temperature over time or the number of days over time. As the temperature increases, this peak moves toward the high temperature side.

Regarding thermogram measurement, the temperature at which an endothermic peak appears depends on the rate of temperature rise during measurement, and the faster the rate of temperature rise, the higher the temperature it appears, but 3-b is appropriate for measurement accuracy. be.

When the above-mentioned endothermic peak temperature (Tp° C.) is left under the same aging conditions, approximately the same temperature is measured for each spinning speed.

However, the limits of changes over time, especially changes in dyeing and crimp characteristics of drawn and false-twisted crimped yarns, vary greatly depending on the spinning speed and even from brand to brand.

According to numerous experiments by the present inventors, the limit of change over time can be determined by the birefringence index (△n) and the endothermic peak temperature (Tp°C), and those that satisfy the condition 'rp≦400△n+57 It was found that there were no problems with dyeability, crimpability, etc., even when the same lot was subjected to stretching and false twisting.

Figure 3 shows the limit line of the endothermic peak temperature (Tp °C) with respect to the birefringence index (△n) of undrawn yarn, and the area below this line, that is, the shaded area, is within the range that can be subjected to draw false twisting as the same lot. be.

Therefore, when stretching and false twisting polyester undrawn yarn whose change over time is unknown, if the thermogram is measured and it is confirmed that the endothermic peak temperature is below the above limit line, there will be little difference in quality due to change over time. This is guaranteed.

When performing stretch false twisting, there are simultaneous stretch false twisting processes (in-draw) in which false twisting is performed at the same time as stretching, and sequential stretch false twisting processes (outdraw) in which false twisting is performed subsequent to stretching.
As the false twisting means, in addition to a spindle method, an internal or external friction method can also be employed.

The draw ratio (DR) during drawing false twisting changes depending on the birefringence index (△n) of the undrawn yarn, and is generally -1,8349
tog (△n)-1,1376≦DR≦-2,178
The range of 91 og(Δn)-1,3509 is preferable, and the heater temperature during stretching false twisting is preferably 160 to 220°C.

According to the present invention as described above, when polyester undrawn yarn whose change over time is unknown is drawn and false-twisted, the presence or absence of change over time can be determined by a very simple measurement, and only those with no substantial change over time can be processed. Since it is possible to select and perform the drawing and false twisting process, it is possible to always produce polyester crimped yarn with uniform quality (crimping performance, dyeability, etc.).

Next, examples of the present invention will be described in detail.

In addition, the measured values in each example are values obtained by the following method.

・Total crimp rate (TC) (%) Make the total with a measuring device and read it with a weight of 0.2 g/denier (10>-□Next, add a weight of 2~/denier) After processing in boiling water for 20 minutes, take out and air dry for 24 hours without weight, read the total length with a weight of 0.2P/denier (12), and read the total length with a weight of 21119/denier (13). From the value, TC is calculated by the following formula.

・Dyeing change (points) Score roll #4 by making DTY processed yarn into stockinette knitting.
000.5 g/l At a bath ratio of 1:100, 6.0% Eastman Blue GLF was added to the sample at 98°C for 20 minutes as a sperm diameter dye, and the sample was stained for 60 minutes at 98°C at a bath ratio of 1:40. .

Thereafter, it was washed with water, dried, and visually evaluated.

The dyeing change (point) is the dyeing difference with respect to the standard sample,
The practical allowable limit is 0.4 points.

- Birefringence (Δn) Birefringence was measured in a tricresyl phosphate using an N2 light source and a Berek compensator inserted into the optical path of an Olympus POM-IT type polarizing microscope.

・Thermogram measurement Measurement was performed using a differential thermal analyzer DT-10 model manufactured by Takasugi Seisakusho, with a sample amount of 100 or more and a heating rate of 5° C./min.

・Intrinsic viscosity [η] It was determined from a 35°C solution of 0-chlorophenol.

Example 1 Polyethylene terephthalate chips with [η) of 0.65 were used in a normal spinning method, and the spinning speed was set to 2000 to give a filament of 150 denier/30 filaments after stretching and false twisting.
m/min, 2500 m/mlyr, 3000m
/mm, 3500m/mm, and 4000m/min.

After aging the obtained spun yarn under each aging condition and measuring the thermogram under the above measurement conditions, the spinner rotation speed was 30 x 10'rpm, the heater temperature was 190°C, and the number of twists was 25.
Stretching and false twisting was carried out using one-way intrusion at 60T/m.

For each case, Table 1 shows the change in Δn of the spun yarn, the endothermic peak temperature, the total crimp rate (TC) change of the crimped yarn, and the dyeing change (comparison with 0 days).

From this, if the endothermic peak temperature (Tp) of the thermogram for △n at each spinning speed is Tp≦400△n+57, it can be drawn and false-twisted as the same lot, and if Tp>400△n+57, it can be drawn and false twisted in a different lot It is clear that a distinction needs to be made.

All humidity over time is 65% RH *: Value exceeding the limit of change over time Example 2 Spinning speed 3000 under the same spinning conditions as Example 1
m1m1n polyethylene terephthalate undrawn yarn (
ΔH=0.038), the endothermic peak temperature CTp℃) of the thermogram was measured under the above measurement conditions for two types of samples A and B whose aging history is unknown.The result was 68℃ for sample A and 76℃ for sample B. An endothermic peak at °C was measured.

Dyeing of the crimped yarns obtained as a result of processing Samples A and B under the same spinning conditions in the post-spinning chamber for 5 days, and Sample C under the same stretching and false twisting conditions as in Example 1. The difference is 100.2 and +0.7 for sample C, respectively, and A and C can be handled as the same lot, but
It can be seen that B and C and A and B cannot be used as the same lot and need to be divided into lots.

[Brief explanation of the drawing]

FIG. 1 shows thermograms of undrawn polyester yarn (spinning speed 3000 m/mLn) aged under various conditions. FIG. 2 shows the change in endothermic peak temperature over time (number of days) under each aging condition. FIG. 3 shows the relationship between the critical endothermic peak temperature over time and the birefringence index of undrawn yarn.

Claims (1)

[Claims] 1. When producing a crimped yarn by drawing and false twisting undrawn polyester yarn having a birefringence index (△n) of 0.015 or more,
The endothermic peak temperature (Tp°C) of the thermogram of the undrawn yarn is measured in advance, and the endothermic peak temperature (Tp°C) is 'rp≦400△n+57 with respect to the birefringence index (△n) of the undrawn yarn. A product made of polyester crimped yarn characterized by stretching and false twisting the same lot of yarn within the range. Base system.