JPS5837418B2 - Polyester sewing machine - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for industrially producing superior polyester sewing thread through a process that is simpler than the conventional method.

The required characteristics of sewing thread are good thermal dimensional stability,
It has excellent dyeability and good sewing ability at high speeds.

In order to satisfy these characteristics as much as possible, conventionally, undrawn yarns made of polyester are spun at a spinning speed of 500 to 1,000 m/min and stretched by a factor of 4.5 to 5.0 at around 85°C.
After heat treatment at around 20℃, 5-1 again at 210℃~220℃
A 0% relaxation heat treatment was performed, but although the yarn produced by this method was thermally stable, sufficient sewability and dyeability were not obtained.

The present invention was made as a result of research to produce a polyester sewing thread free from the above-mentioned drawbacks.The present invention was made as a result of research to produce a polyester sewing thread free from the above-mentioned drawbacks. .03≦△n
≦0.11 is produced, and the undrawn yarn is
Stretched at a temperature of 180°C or higher and 220°C or lower, and then heat-treated at a temperature of 180°C or higher and 240°C or lower under constant length, shrinkage or elongation within a dimensional change of ±5%, with a cutting elongation of 36% or less and a boiling water shrinkage rate. 2.0 or less and a melting point of 260°C or more, and by twisting this fiber to make sewing thread, sewing thread with excellent heat stability, dyeability, and sewability is manufactured. .

To explain the present invention in more detail, it is necessary that the polyester is made up of 95% or more polyethylene terephthalate units, and if it is less than 95%, it will be thermally stable and can be used at high speeds. It cannot be used as a sewing thread with the sewability (defined later).

Polyester that satisfies this condition is spun at high speed and has birefringence △.
It is necessary to perform spinning so that n satisfies 0.03≦△n≦0.11.

When Δn is less than 0.03, the dyeability of the final fiber is poor and thermal stability cannot be obtained, and when it exceeds 0.11, the strength of the fiber becomes weak and it is difficult to use it as sewing thread.

Normally, the spinning speed at which the undrawn yarn △n falls within this range is 3,oo
om/min to 6,000 m/min.

Next, this undrawn yarn is drawn at a temperature of 85°C or higher and 220°C or lower, and then heat-treated at a constant length, shrinkage, or elongation so that the dimensional change is within ±5% at a temperature of 180°C or higher and 240°C or lower. Let's do it.

If the drawing temperature at this time is 85°C or lower, the strength as a sewing thread will not be lost, and if the drawing temperature is 220°C or higher, the fiber will have low strength.

Further, the heat treatment temperature is related to thermal stability, and if the temperature is 180° C. or lower, the thermal stability that can withstand the subsequent dyeing process cannot be obtained.

Furthermore, temperatures above 240°C are not preferred as sewing threads do not lose their strength.

In addition, in the heat treatment, if relaxation is to be imparted, the heat treatment should be 5% or less, and if elongation is to be imparted, the heat treatment should be 5% or less.

Relaxation treatment of 5% or more tends to create fused fibers and also reduces strength.

Further, elongation of 5% or more lowers Young's modulus and is not favorable for high-speed sewing performance.

Under the above conditions, the boiling water shrinkage rate was 2.5% or less, the cutting elongation was 36% or less, and the melting point was measured with a finger thermometer at a temperature increase rate of 10°C/min under the above conditions. 260
Polyester fibers with a temperature of ℃ or higher.

If the boiling water shrinkage rate is 2.5% or more, it is not preferable because one additional process (steam setting process) is required when used as sewing thread.

Moreover, if the elongation at break is 36% or more, the Young's modulus will be low, which is also not preferable as a sewing thread.

In the present invention, such a polyester fiber is used as a raw yarn and twisted by a conventional method to produce a sewing thread.

Generally, it is preferable to combine two to four multifilament yarns of 50 to 100 deniers.

Next, the differences between the polyester sewing thread produced by the present invention and the polyester sewing thread produced by the conventional method are shown in drawing curve diagrams.

In the attached drawings, A is a conventional polyester sewing thread, and B is a sewing thread of the present invention, and the dyeing process, twisting process, etc. conditions for the sewing threads are the same, and the denier (de) is also the same.

A and B have almost the same initial Young's modulus, but the load at 4 to 5% elongation is higher in B, and then, near the cutting point, A has a higher load, which is reversed from B.

The definition of sewability here is when four layers of 65% polyester fabric and 35% rayon plain fabric with a fabric weight of 150SF/ffl can be sewn for 1 minute without breaking for 60 seconds.1
Score 0 points.

Therefore, a time of 30 seconds is given as 5 points, and this score is calculated based on the number of revolutions of the sewing machine. Generally speaking, the higher the speed, the lower the sewability becomes.

The material with the sewability of B has good sewability at high speed and has little relation to the cutting strength.

Also, the high melting point means that the needle temperature on a high-speed sewing machine is 250℃.
Since the temperature rises to nearly ℃, the polyester is fused and broken, but if the melting point is high, this fusion is less likely to occur, and it is thought that the sewability will be improved accordingly.

This will be explained in detail in Examples below.

Example 1 Polyethylene terephthalate with an intrinsic viscosity [η]-0.7 bright was heated at 3,000 m/min, 4,000 m/min, 5,
High-speed spinning was performed at OOOm/min and 6,000m/min, and each undrawn yarn was spun at 85°C with 1.7, 1.4, 1.2
, stretched 1.1 times, and heat-treated at 210° C. to obtain a 70-denier 24-filament yarn for sewing thread.

These yarns were first-twisted and second-twisted to make sewing thread (#50) by plucking three yarns together and dyed at 130° C. to test the sewability of the sewing thread.

Table 1 shows these physical property data.

As is clear from Table 1, it can be seen that the boiling water shrinkage is lower than that of the comparative example (conventional product), the melting point is higher, and the sewability score of 4,000 times/min is better.

Also, the dyeing rate was high, indicating that it dyes well.

[Brief explanation of the drawing]

The drawings show load-elongation curves of sewing thread according to the present invention method and sewing thread according to the conventional method. Line A is the load-elongation curve of the sewing thread according to the conventional method, and line B is the load-elongation curve of the sewing thread according to the present invention.

Claims (1)

[Claims] 1. Birefringence Jn is obtained by high-speed spinning of polyester whose 95% or more is composed of polyethylene terephthalate units.
An undrawn yarn in which 0.03≦△n≦0.11 is produced, the undrawn yarn is drawn at a temperature of 85°C or higher and 220°C or lower, and further dimensional change occurs at a temperature of 180°C or higher and 240°C or lower. ±5
% or less, heat treatment is performed under constant length, shrinkage, or elongation to produce polyester fibers with a cutting elongation of 36% or less, a boiling water shrinkage rate of 2.5% or less, and a melting point of 260°C or higher, and the fibers are twisted. A method for producing polyester sewing thread, characterized by: