JPS5818445B2 - Polyester fiber manufacturing method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for producing polyester fibers suitable for drawing and false twisting by high-speed spinning.

Recently, polyethylene terephthalate was sold at 2,000 to 450
A method has been proposed for producing polyester fibers suitable for draw-false twisting by high-speed spinning at a speed of 0 ml to 1 ml.

However, such polyester fibers have the disadvantage that they not only undergo large dimensional changes due to heat, but also are unstable over time and cannot withstand long-term storage or transportation.

Furthermore, the cross-sectional deformation of the filaments during the drawing and false-twisting step is large, and the texture of the resulting bulky textured yarn is therefore poor.

The present inventors have arrived at the present invention as a result of intensive research to eliminate these drawbacks in conventional high-speed spinning.

That is, in the present invention, a synthetic polymer consisting essentially of polyethylene terephthalate is melt-spun through a spinneret, the spun yarn is cooled to a temperature lower than (glass transition temperature of the polymer + 40°C), and then (0 ,06V+206)
After being instantaneously heat-treated with gas heated to a temperature of ~ (0,11V + 335) °C [where ■ is the spinning take-off speed m/mjn], the yarn was
This method is characterized by taking over at a speed of n.

In the present invention, the term "synthetic polymer substantially consisting of polyethylene terephthalate" generally refers to polyesters containing 85 mol% or more of ethylene terephthalate units and blends containing the polyesters as a main component.

Examples of the third component that can be copolymerized in a proportion of 15 mol% or less include isophthalic acid, 2,6-naphthalene dicarboxylic acid, adipic acid, oxalic acid, trimellitic acid, pyromellitic acid, diethylene glycol, propylene glycol, and cyclohexane dimeta. Tool, Pentaerythritol, P-
Oxybenzoic acid or derivatives thereof can be mentioned.

These polyesters also contain small amounts of additives, such as
There is no problem in containing matting agents, coloring agents, stabilizers, flame retardants, etc.

In the present invention, among the above polyesters, the intrinsic viscosity (35°C
(measured with an O-chlorophenol solution) of 0.5 or more, and a range of 0.55 to 0.95 are suitable.

According to the present invention, the polyester is melt-spun from a spinneret to form a fiber, and the spun yarn is spun at a temperature lower than Tg+40°C, preferably from Tg-20°C to Tg+20°C.
Cool to a temperature of °C.

Here, Tg represents the glass transition temperature of the polyester constituting the spun yarn, and the Tg of the polyester is measured by the method described in US Pat. No. 2,556,295.

The Tg of amorphous polyethylene terephthalate is about 70°C.

The temperature during melt spinning from the spinneret is preferably 20 to 50°C higher than the melting point of the polyester, and in order to cool the spun yarn, the spinning process is performed in a cooling section 1 to 1.5 m below the spinneret. It is preferable to uniformly cool the yarn by blowing cooling air onto it.

The spun yarn cooled to a predetermined temperature in this way is immediately (0,06V-1-206) to (0,11V
5) C.C. However, ■ is an instantaneous heat treatment using a gas heated to a temperature of 2/min"J, such as heated air, inert gas, steam, etc.

If the yarn temperature immediately before undergoing this heat treatment is higher than Tg + 40°C, it will be difficult to perform the heat treatment uniformly and the resulting yarn will have poor homogeneity. It should be done at the stage when the

However, heat treatment after the yarn has been completely cooled and solidified has almost no effect, so it is preferable to carry out the heat treatment before the temperature becomes lower than Tg-20°C.

Also, the temperature of the heated gas is (0.06V+206)℃
If it is lower, the effect of heat treatment will be small and the object of the present invention will not be achieved.

On the other hand, the temperature of the heated gas is (0,11V+335)℃
If it is higher, fusion between single yarns and yarn breakage occur frequently, which is not preferable.

This heat treatment can be easily performed by jetting gas heated to a predetermined temperature toward the running yarn from a slit with a length of 5 to 30 Cr/L.

At this time, it is preferable to bundle the yarns introduced into the heat treatment zone to such an extent that the single yarns do not come into close contact with each other.
It is preferable to provide a ring-shaped guide of about 3.0 cm.

In this way, yarn breakage and denier unevenness in the spinning process can be significantly reduced.

After leaving the heat treatment zone, the yarn is coated with an appropriate finishing agent and then passed through a pair of godet rollers or directly through a winder.
000~4500 m1m1n (preferably 2500~
Pick up at a speed of 4,000 m/f.

If the take-up speed is less than 2000 m1m1n, no matter how the heat treatment temperature is adjusted during the heat treatment, not only yarn breakage will occur and the spinning condition will deteriorate, but also the dimensional stability against heat of the resulting polyester fibers will deteriorate. Stability over time, resistance to cross-sectional deformation, etc. are not improved.

On the other hand, when the take-up speed exceeds 4,500 m/min, no significant improvement in the above characteristics is observed even if heat treatment is performed.

In carrying out the present invention, it is preferable to apply a turbulent flow or a swirling flow of gas to the yarn before winding it to impart interlace or alternate twist to give the yarn cohesiveness.

According to the method of the present invention as described above, the birefringence is 0.09 to
0.14, density 1.371'? /cn1 or more, polyester fibers with relatively high orientation and crystallinity can be obtained.

This polyester fiber has a strength of 3 to 4z/Da.
It has physical properties such as elongation of 40 to 80% and submerged shrinkage of 8% or less, and has a stable structure that is quite different from conventional high-speed spinning polyester fibers.

Therefore, the polyester fiber produced by the method of the present invention has excellent stability over time, and there is no self-stretching or shrinkage of the yarn after it is wound into a package. There is no risk of staining.

Furthermore, the fibers can be easily handled when threaded into a drawing false-twisting machine, and a bulky processed yarn with good texture can be obtained with less cross-sectional deformation due to the drawing false-twisting process.

When polyester fibers are drawn and false-twisted according to the method of the present invention, either an in-dry or out-dry method may be used (processing temperature: 150-240°C, stretching ratio: 1.05-240°C).
By stretching and false twisting under the conditions of 1.30, it is possible to obtain a bulky textured yarn with good crimp performance and texture.

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

Example 1 A chip of polyethylene terephthalate (melting point 261°C, Tg 68°C) with an intrinsic viscosity of 0.64 was heated at 290°C to have a pore size Q.
, was spun from a spinneret with a diameter of 4 mm and 7 holes, and the spun yarn was
Air at about 25°C is blown from the side to rotate the yarn at 70°.
After cooling to C, it is concentrated by a ring-shaped guide with a diameter of IQ mm, and then heated to the temperature shown below is blown through a slit with a length of 10 sieves for instantaneous heat treatment, and then finished with an oiling roller. The material was applied with a coating agent, taken up by a pair of godet rollers at a circumferential speed of 3500 m1m1n, and wound up with a wine gourd.

The physical properties of the fibers obtained under each condition are shown in Table 1 below.

Experiment A1 is a comparative example.

In case 1, the submersion shrinkage rate was large, and changes over time were observed after being left in an atmosphere of 40° C. and 65% RH for one month.

Example 2 After melting a polyethylene terephthalate chip with an intrinsic viscosity of 0.88 at 300°C, the pore diameter Q is 7 mmφ and the number of holes is 1.
Spun from the spinneret No. 2, air at about 25°C is blown horizontally against the spun yarn, and when the fiber reaches 65°C, heated air is jetted through the slit to instantaneously After heat treatment, a finishing agent was applied using an oiling roller, and the material was taken up with a pair of godet rollers and wound up with a wine gourd.

At this time, the relationship between the take-up speed, the temperature of the heated air accompanying it, and the physical properties of the undrawn yarn is as shown in Table 2 below.

Experimental plate 6.10 is a comparative example.

In flat 6, yarn breakage occurs frequently during spinning, and the spinning condition is poor.

Furthermore, the performance of AIO is not much different from that of ordinary high speed spinning yarn of 5000 m/min.

Example 3 After spinning the undrawn yarn of Example 1 and Experimental Shop 3, the temperature was 65% at 25°C.
After leaving it in the RH room for one day, 4 threads were tied together and
The material was supplied to a 8-600 type draw false twisting machine and subjected to draw false twisting under the conditions of spindle rotation speed 29.5 x 104 rpm, twist coefficient 0.95, and heater length 100 crrL while changing the draw ratio and processing temperature. It was wound with % overfeed.

``O-type'' obtained by changing the stretching ratio and processing temperature
The properties of the textured yarn are as follows.

Note that TC and dyeing (L value) are values measured by the method described in British Patent No. 1,333,679, and streaks are the result of dyeing a stockinette knit sample and visually determining it.

In addition, the oblateness is b / a, where b is the longest length of the inner diameter (diagonal line) in the single yarn cross section of the textured yarn, and a is the longest diameter perpendicular to the longest diameter. Defined as the average value of 20 measurements.

The closer the oblateness is to 1, the closer to a perfect circle it is.

Claims (1)

[Claims] 1. A synthetic polymer consisting essentially of polyethylene terephthalate is melt-spun through a spinneret, the spun yarn is cooled to a temperature lower than (the glass transition temperature of the polymer + 40°C), and then immediately (0,06V+206) ~ (0,11
v+3i5)℃ [However, ■ is the spinning take-off speed m/min
1. A method for producing polyester fibers, which comprises instantaneously heat-treating the fibers with a heated gas having a temperature of 2,000 to 4,500 m.