JPS62156311A - Production of polyester fiber suitable for rubber-reinforcing woven fabrics - Google Patents

Abstract

PURPOSE:A yarn drawn under specific conditions is heat-set under specific conditions to obtain a polyester yarn which has high elasticity and low shrinkage, thus is suitably used in woven fabrics for rubber reinforcement. CONSTITUTION:A polyester with an intrinsic viscosity of over 1.1, preferably 1.3-1.5 is melt-extruded into filaments, solidified by cooling and taken up at a speed of over 1,500m/min, preferably 2,000-6,000m/min, and drawn at a ratio of less than 5, preferably 1.5-4. After completion of drawing which corresponds to more than 80% of the total draw ratio, heat treatment is conducted under multistage stretching of inched step to give polyester fiber with an intrinsic viscosity of over 0.92. The heat-set temperature is preferably over 150 deg.C.

Description

[Detailed description of the invention] [Industrial application field] The present invention relates to a method for producing industrial polyester fibers.

More specifically, the present invention relates to a method for producing high-strength polyester fibers having a high elastic modulus and good dimensional stability, which are suitable for rubber reinforcing fabrics.

[Conventional technology]

Conventionally, polyester fibers, especially polyethylene terephthalate fibers, have been widely used as industrial materials, especially rubber reinforcing materials, due to their excellent mechanical properties.

The use of polyester fibers in passenger car tires in particular has been remarkable, and with the shift to radial tires in recent years, polyester fibers have become highly strong, have a high elastic modulus, and have good dimensional stability (i.e., low shrinkage). ), the development of polyester fibers is strongly desired.

In response to this demand, Japanese Patent Application Laid-Open No. 57-154410 discloses a complete line of polyethylene terephthalate fibers with high elastic modulus and low shrinkage by drawing undrawn yarn with birefringence in a specific range and spinning at a relatively high spinning speed. method is disclosed. This method certainly has a higher modulus of elasticity and lower shrinkage than the conventional technology. &
This method is now becoming the mainstream technology for producing industrial polyester fibers.

[M points while the invention is trying to solve]

However, in recent years, tire manufacturers' polyester raw materials, 6
The demand for high elastic modulus and low shrinkage rate has become increasingly severe, and it has become impossible to obtain fibers of a sufficiently satisfactory level even with the above-mentioned techniques.

Therefore, the inventors of wood used a material with a higher modulus of elasticity and a lower shrinkage rate;
1.・It was found that the processing conditions from the end of the clearing to the removal of the fibers have a large effect on the elastic modulus of the fibers.

In other words, in the above-mentioned method, after the fiber is drawn, it is heat-treated at a high temperature with a final drawing roller in order to improve spinning properties and reduce shrinkage, and then it is relaxed and wound, but this process causes a significant decrease in the elastic modulus. It turned out that he was inviting.

Therefore, the present inventors investigated a method (C) of improving the processing method after the end of drawing of polyester fibers and before winding them up to increase the modulus of elasticity and reduce the shrinkage rate of the fibers.

As a method for increasing the elastic modulus of fibers, for example, Japanese Patent Application Laid-open No. 5
No. 9-400711 describes a method of stretching and heat-treating crystalline highly oriented polyester fibers under a temperature gradient, and the examples show an example of stretching under a temperature gradient using a so-called reverse Chi-29 roller. There is. However, even if this method is simply carried out, although the effect of improving the elastic modulus is observed, the shrinkage rate of the fiber becomes higher than the desired level. Fibers with low shrinkage cannot be obtained.

In addition, as a method for reducing the shrinkage of fibers, as mentioned above, the usual method is to apply heat centrifugation using a high-temperature roller, but this method greatly reduces the elastic modulus of the fibers and makes it difficult to unshape them. cormorant. Furthermore, JP-A No. 49-+323j7 and JP-A No. 4
Publication B-28371 discloses a method of obtaining yarn with a low shrinkage rate by heat-treating it under shrinkage after drawing, but although this method does reduce the shrinkage of the yarn, it does not improve the essential elastic modulus. The dog's hearing deteriorates.

As described above, conventional techniques naturally have limitations in producing polyester fibers with high elastic modulus and low shrinkage.

SUMMARY OF THE INVENTION It is an object of the present invention to solve the above-mentioned problems and to provide a method for producing polyester fibers suitable for rubber reinforcing fabrics that have a higher modulus of elasticity and a lower shrinkage rate than polyester fibers obtained by conventional methods. This objective can only be achieved by strictly controlling the fiber manufacturing conditions up to the end of stretching and the heat sink conditions after the stretching is substantially completed.

[Failure to solve the problem]

The purpose of the present invention is to produce polyester fibers by: (1) using polyester with an intrinsic viscosity of 11 or more as a raw material polymer and discharging it from a spinneret; and (2) after cooling and solidifying the spun yarn, taking it off at a take-up speed of 1500.
(3) Continue to/or once wound up, stretch the vaginal filament in one or multiple stages at a stretching ratio of 5 times or less. 4) Stretching of 80% or more of the total stretching ratio is completed. Achieved by a method for producing polyester fibers suitable for rubber reinforcement fabrics, which is then heat-treated while adding a multi-stage [divided small-sized stretch] to produce polyester fibers with an intrinsic viscosity of 0.92 JJ. can.

The present invention will be explained in more detail below.

The polyethyl in the present invention is a polyester having 90 moles of polyethylene terephthalate structural units and may contain less than 10 moles of a copolymer component, but is preferably a polyethylene terephthalate containing substantially no copolymer components.

The @1 viscosity of the raw material polymer used in the production of the polyester fiber of the present invention needs to be 1.1 or more. If the intrinsic viscosity of the raw material polymer is less than 11, a high-strength yarn with high elastic modulus and low shrinkage rate, which is the object of the present invention, cannot be obtained. This is because if a polymer with an intrinsic viscosity of less than 1.1 is used for spinning, the intrinsic viscosity of the resulting fiber will be less than 0.92 due to the decrease in viscosity during spinning, and the elastic modulus and strength will not reach the desired level. This is not because the 111 fatigue properties of the yarn are reduced. If you try to use a polymer with a viscosity of less than 11 to suppress the drop in viscosity during spinning and run all the fibers of 0.92 or more, the spinning temperature must be extremely low, and the resulting yarn will be asymmetrical and have a significantly lower strength. decreases. Therefore, in the present invention,
(092 yarn made using polymer with limiting viscosity of 1.1 or more)
The limiting viscosity f! & Must be navy blue.

In addition, in order to further exhibit the effects of the present invention, the intrinsic viscosity of the polymer should be ii f: 1.2 or more and less than 1.5, more preferably 1.5 or more and less than 1.5, and the fiber with an intrinsic viscosity of 0.951υ or more should be used. It is preferable to set it as associate.

Further, in the present invention, it is necessary to use polyester having an intrinsic viscosity of 1.1 or more as the raw material polymer, discharge it from a die, cool it and solidify it, and then take it off at a take-up speed of 1500 m/7 min. If the take-up speed is less than 1500 m7/min, the elastic modulus will be low and the shrinkage rate will be high, making it impossible to obtain the desired polyester fiber. Furthermore, in order to obtain a high elastic modulus and low shrinkage rate, weir speed t! It is preferable that the total distance is 2000 m for 7 minutes or more.

In addition, a take-up speed of 6000 m/min or less is preferable from the viewpoint of strength and productivity.

Furthermore, in the present invention, it is necessary to continuously/or once wind up the above-mentioned undrawn yarn and then draw it in one stage or in multiple stages at a stretching ratio of 5 or less. When the IL stretching ratio exceeds 5 times, not only does productivity deteriorate and stable production becomes impossible, but also the shrinkage rate increases, which is undesirable. The most preferable range of draw ratio (-, 'I' also depends on the take-up speed of undrawn yarn, but it is 15 to 4
It is a 7π range of 11η.

For the stretching in the present invention, methods using hot rollers, hot plates, slit heaters, steam heaters, steam jets, and air jets are preferably applicable.

Furthermore, in the present invention, the drawn yarn obtained by satisfying the limited conditions as described above is heat-set under specific conditions to achieve a high elastic modulus.
It becomes possible to produce polyester fibers with low shrinkage. Specifically, after the stretching of 80% or more of the total stretching ratio is completed, it is necessary to perform heat treatment while applying small stretches divided into multiple stages. Even if the above-mentioned heat treatment is performed before the drawing of 80% or more of the total drawing ratio is completed, the shrinkage rate of the yarn increases because the fiber is drawn to a high ratio again during or after the heat treatment. Put it away. Therefore, it is necessary to carry out the heat treatment while adding small stretches divided into multiple stages after completing stretching of more than 80% of the total stretching ratio. As a specific method, for example, while using a tapered roller system in which the roller diameter gradually increases from the inlet side to the outlet side,
Examples of heat treatment include using a hot plate, external heating, or using the roller itself as a heating roller.

In this way, by promoting the crystallization of the heat-sodified fibers while highly tensioning the threads, the elastic modulus is not reduced.
This allows for a lower shrinkage rate. The stretch rate applied during heat treatment (i.e., the ratio of the inlet diameter to the outlet diameter when using a tapered roller) is preferably 105 or more and 1.25 or less, and the rate of change in the applied stretch is preferably substantially constant. . Furthermore, the temperature of heat treatment is 150℃
The temperature is preferably 210° C. or higher, and more preferably 210° C. or higher. Furthermore, it is more preferable to perform the heat treatment by gradually increasing the heating temperature fσ of the yarn.

In addition, 5 the method of the present invention has a total denier of 1000 to 50
00 denier, the effect is even more pronounced when it is applied to the production of drawn borie terephthalate yarn with a single yarn 'y' denier of 2 to 7 deniers.

The effect of the present invention in terms of high elastic modulus and low shrinkage is to prevent the crystallization of the yarn as much as possible before the final heat treatment, making it a highly amorphous highly oriented yarn, and then, during the heat treatment, to make it a highly oriented amorphous yarn under small grooves with a roller. This is more effective than causing crystallization all at once, and from this point of view, the temperature of the group of rollers before heat treatment is not made too high while adding small stretches divided into final stages. (specifically below the crystallization temperature of the thread (110 to 12
(below 0°C)) is preferred.

〔Example〕

The present invention will be explained in more detail with reference to Examples below. Note that the method for measuring the characteristic values defined in the present invention is as follows.

A Ultimate strength (IV) Ornochlorophenol (+2
．． Dissolve 8 g of the sample in 1 (1 me) and use an Ortwald viscometer to determine the relative viscosity change ηr using the following formula.

IV=0.02421r+0.2634B1 Strong elongation, medium elongation S-
We measured the 6 curves and found the strong middle e. Also, the middle elongation was 45g/
The elongation corresponding to the stress d was determined from the above SS curve.

C9 Elasticity Modulus of the above S-6 curve: Continuing the strength T (g/d) corresponding to the elongation S (%) on a straight line from the scan line, M2 TX100. The elastic modulus M (g/'a) was determined as /S.

D. Dry heat shrinkage rate Sample was taken in a skein shape and placed in a temperature controlled room at 20°C and 65% RH for 2 hours.
After leaving for more than 4 hours, 0.1 g/d of sample
at a length measured under a load corresponding to . A sample of
After being left in an oven at 150° C. for 30 minutes under no tension, it was taken out from the oven and left in the temperature-controlled room for 4 hours, and the load was applied again to calculate the measured length el using the following formula.

Dry heat shrinkage rate (la ll)/eoX100 (%)
E. Anti-fatigue 2-GY fatigue test (Gnodyer Mallory Fateig test) According to ASTM D885. Setting the tube internal pressure to 3.5, 9/cn G, rotation speed 850 rpm, and tube angle change to 80°C, find the time until the tube ruptures. Good level is ○, conventional level is Δ, and less than conventional level. The level is indicated by ×.

Actual foil example 1 A polyethylene terephthalate chip with a 1i limiting viscosity change (hereinafter referred to as IV) of 1.3 is melted in an extruder and spun from a spindle with a polymer temperature of 298°C and a pore diameter of 0.6mm and 192 holes. did. At the bottom of the nozzle, a heating cylinder of 30 knots was attached via the spinning machine block and a heat insulating plate, and the ambient temperature was set to 1.
The temperature was 300°C.

After the spun yarn passes through the heating cylinder, it is cooled and solidified by the cooling lice blown out from the chimney installed under the heating cylinder.
After being applied with an oil agent by an oiling roller, it was taken off at a take-up speed of 2500 m/min.

After winding up the above undrawn yarn, the following (Al, (B)
Stretched by two methods, 1000 denier, 1
92 filament, was wound as a fiber of engineering V1.01.

As is clear from Table 1, the heat treatment method of the present invention [Bl] significantly increases the strength and elastic modulus, lowers the intermediate elongation, and decreases the dry heat shrinkage rate compared to the conventional constant length heat treatment methods 1p and I. It can be seen that a high elastic modulus and a low shrinkage rate have been achieved.

Example 2 The material V of the tips to be supplied and the degree of polymer 11 during spinning were changed, and Sanople with a different drawing material V was used in Example 1-(
By the method of Bl, the stretching ratio is distributed under conditions such that the upper limit of the ratio can be obtained at each level.

The physical property values are summarized in Table 2.

As is clear from ♂72, Sennobue V +, only in Ya 2-1.2-5 with Ito TV 0.92 or higher,
It can be seen that the effects of the present invention have been achieved.

Example The filter take-up speed was changed in the range of 500-3000 m/min, and the stretching ratio was set to 10QO denier-192 filament under the same conditions as Bl, at the upper limit at each spinning speed j. A 1fjl oki yarn of /t was used. Each is shown in A″DD physical properties 5.

As is clear from Nose 6 in Table 3, if the take-up speed Ir is less than 11,500 m/min, although the strength increases, the effects of improving the elastic modulus and reducing the shrinkage rate of the present invention cannot be obtained.

Example 4 The same conditions as Example 1 were used, except that the magnification distribution during stretching was changed. The results are shown in Table 4.

Table 4 The heat treatment, which was performed while adding small stretches divided into multiple stages, was carried out using a rho plate in the same manner as in Example 1.

As is clear from Table 4, in Example 4, in which stretching of 80 mm or more was not completed before the heat treatment roller, the dry heat shrinkage rate was high and the object of the present invention could not be achieved.

〔Effect of the invention〕

The polyester fiber obtained by the method of the present invention has a strength of 8.2 g/d, an elastic modulus of 1.5 g/d1, an intermediate elongation of 5.5, and a dry heat shrinkage of 5. It has high strength, high elasticity, and low shrinkage, and can be manufactured with good operability.

The polyester fiber of the present invention exhibits excellent fatigue resistance when used as a comb reinforcing fabric, and tires manufactured using the fiber as a tire cord exhibit excellent performance such as handling stability.

Claims (1)

[Claims] When producing polyester fibers, (1) polyester with an intrinsic viscosity of 1.1 or more is used as a raw material polymer, and is discharged from a spinneret (2) the spun yarn is cooled and solidified, and then taken at a take-up speed of 1500 m/min.
(3) Subsequently/or once wound, the yarn is drawn in one or multiple stages at a draw ratio of 5 times or less; (4) the yarn is drawn at a draw ratio of 80% or more of the total draw ratio (5) A method for producing polyester fibers suitable for rubber reinforcing fabrics, characterized by heat-treating the fibers while applying small stretches divided into multiple stages after completion of the treatment, and (5) forming polyester fibers having an intrinsic viscosity of 0.92 or more.