JPS5813718A - Polyester fiber - Google Patents

Abstract

PURPOSE:The titled fibers, consisting of ethylene terephthalate units, etc., showing a positive gradient at any point in a load-elongation curve, and having a stress increment before the breaking of a specific value or below, and high modulus, low shrinkage and improved fatigue resistance, and suitable for reinforcing rubber structures, etc. CONSTITUTION:A polyester consisting of ethylene terephthalate as main structural units without adding titanium oxide thereto is melt spun to give fibers, which are oiled with an oiling agent, led to taking off rollers, and directly withut winding drawn with steam jets jetted at an angle of 45 deg. thereon to give the aimed fibers showing a positive gradient at any points in the load-elongation curve (curve 1), and a stress increment (DELTAL) at the final elongation of 2.5% before the breaking to a breaking point (a) <=0.4g/denier and a shrinkage in dry heat <=17% at 175 deg.C, and suitable for reinforcing rubber structures. The curve 2 is a load-elongation curve of the conventional fibers for reinforcing rubber structures.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to polyester fibers, and more particularly to polyester fibers that have high modulus, low shrinkage, and excellent fatigue resistance and are suitable for reinforcing rubber structures.

Fibers made of polyester, especially polyethylene terephthalate, have many excellent properties and are therefore used not only for clothing, but also for rubber structures such as tires, belts,
conveyor belt.

It is also used to reinforce timing belts, etc.

Polyester fibers for reinforcing Kalkom structures are required to have high strength, high modulus, and low shrinkage. Conventionally, in order to obtain high-strength polyester fibers, a method has been known in which undrawn yarn with a high degree of polymerization is drawn in multiple stages at a high magnification and then sufficiently heat-treated at a high temperature. In order to obtain an undrawn yarn that can be easily drawn in multiple stages at such a high magnification, the atmosphere directly below the spinneret is maintained at a high temperature and the spun yarn is slowly cooled to increase the degree of orientation of the undrawn yarn. A method has been adopted to lower the However, when polyester fibers with a high degree of polymerization are drawn in multiple stages at a high magnification, the shrinkage rate of the resulting drawn yarn increases, and the above method cannot obtain fibers with sufficiently low shrinkage.

In order to obtain a high modulus polyester fiber, in order to reduce defects in the amorphous part and increase the degree of orientation of the amorphous part, undrawn polyester yarn with a relatively low degree of polymerization is drawn in multiple stages at a magnification. There are possible ways. However, this method reduces the strength of the resulting fibers.

Furthermore, as a method for producing low-shrinkage fibers, undrawn yarn with a low degree of polymerization is drawn in multiple stages, and undrawn yarn with a high degree of polymerization is used and heat-treated in a shape that allows limited shrinkage after stretching. The method is known. However, even with these methods, the strength of the fibers obtained is reduced.

Conventionally, it has been difficult to produce polynisle fibers that satisfy K, high strength, high modulus, and low shrinkage. Moreover, as mentioned above, the high-strength polyester fiber obtained by multi-stage drawing of high degree of polymerization unfinished polyester yarn at high magnification and sufficient heat treatment at high temperature not only does not have a sufficiently high modulus but also shrinks and The rate cannot be lowered to the level of light,
Furthermore, strength retention and fatigue resistance are insufficient, and there is a strong demand for improvement in fatigue resistance.

The inventor has high strength, high modulus, and low shrinkage.

We conducted extensive research to provide a polyester fiber suitable for reinforcing rubber structures that has excellent strength retention and fatigue resistance, but we were unable to achieve any success within the range of conventional high-strength polyester fiber production methods. I didn't. As a result of a fundamental review of conventional technology, when polyester fibers are used for reinforcing rubber structures, it is customary to melt-spun high-polymerization polyester in a high-temperature atmosphere to obtain fibers with as little orientation as possible.
Multi-stage stretching at high magnification, heat treatment at high temperatures to produce high-strength fibers, which are then undercoated and/or twisted to form cords, coated with adhesive, and then fully tensioned and heat treated at high temperatures. However, we focused on the fact that it is often subjected to severe heat treatment, as is clear from the fact that it is disposed in a rubber structure and vulcanized after it is cured. That is, the polyester fibers that have been sufficiently crystallized and adjusted to an optimal state by stretching and heat treatment after spinning are subjected to severe tension heat treatment again, so that in the final rubber structure, The inventor of the present invention focused on the fact that the polyester fiber has undergone deterioration and deterioration, and as a result of further study in order to provide a polyester fiber that exhibits the best performance when made into a final product, the inventor has found that it has the novel characteristics of the present invention. We have now discovered a polyester fiber.

That is, the present invention is made of polyester containing ethylene terephthalate as a main constituent unit, exhibits a positive slope at any point in the load-loading curve, and has a positive slope at any point in the load-loading curve, and the last 2.5 points before breaking.
The stress increment of 5-chi elongation is 0.471/ds or less and 5
The present invention relates to a polyester fiber suitable for reinforcing rubber structures, which has a dry heat shrinkage rate of 17 or less at 75°C.

The characteristics of the polyester fiber of the present invention will be explained with reference to the accompanying drawings. The figure shows the load-loading curve, and the curve (11
is a load-loading curve of the fiber of the present invention, and point P) is the breaking point. In the fiber of the present invention, the last 2,
The stress increment l-L at 5% elongation must be 0.4 y/da or less (the curve in the figure (at +1, △L is approximately 0
．． 2 JF /de).

If this stress increment ΔL exceeds 0.4 g/de, thermal deterioration occurs during heat treatment after cord production or during vulcanization, and the object of the present invention cannot be achieved. On the other hand, the load-loading curve of the conventional conventional polyester fiber for reinforcing rubber structures is curve (2), and the stress increment ΔL during the final 25-inch elongation before breakage is as much as 1.41/da. However, thermal deterioration during heat treatment after hood fabrication cannot be avoided. It should be noted that if the cutting strength of the fibers of the present invention is too high, thermal deterioration during heat treatment after making the hood tends to increase, and conversely, if the cutting strength is too low, even if the heat treatment after making the cord is performed under optimal conditions, it will not be sufficient. There is a tendency that strength cannot be obtained, so 61/d@ or more? , 51 /de is preferably in the ungrooved range. In the figure, the cutting strength of curve (1) is about 7-01 /de, and the cutting strength of curve (2) is about 8.21 /de.

Furthermore, the fiber of the present invention must have a dry heat shrinkage rate of 17 inches or less at 175° C. in addition to the above-mentioned load-stretching curve characteristics. Those whose shrinkage rate exceeds xr%,
Even if the load-loading curve characteristics are satisfied, the cord undergoes significant alteration and deterioration during heat treatment after cord production, and further deteriorates during vulcanization. In addition, if the dry heat shrinkage rate at 175°C is too low, the shrinkage performance may not be sufficiently improved by heat treatment after cord production, and the shrinkage rate may worsen (i.e. increase). Preferably it is in the range of 15%. Furthermore, although it is related to this dry heat shrinkability, the maximum heat shrinkage stress of this fiber is 055~o, s
It is preferable to set the s I /do to a range of s I /do, thereby increasing the effect of reducing shrinkage caused by heat treatment after producing the hood.

Although the polyvinis dire fiber of the present invention having the above-mentioned load-loading curve characteristics and dry heat shrinkage characteristics is inferior to conventional polyester fibers for reinforcing rubber structures, the fiber of the present invention is , which is twisted and/or first twisted to form a cord, applied with an adhesive, heat treated, placed in a rubber structure and vulcanized, exhibits the best performance in the rubber structure obtained, The final rubber structure exhibits properties far superior to those of conventional rubber structures.

It is not necessary to particularly limit the degree of polymerization, birefringence, etc. of the polyester fiber of the present invention, but if sufficient strength is required in the final rubber structure, it is desirable that the intrinsic viscosity is 064 or more, %Ko,y or more is preferable. The refractive index is at least 0. ! 1 is desirable, especially 0.
15 or more is preferable. Note that the intrinsic viscosity referred to in this FIAIIMi document was determined using an Ortsuk 9t2 phenol solvent solution at 35°C.

The polyester fiber of the present invention has an intrinsic viscosity of 0.64 or more,
Preferably 0.7 or more, more preferably 0.85 or more polyester is spun in a molten state in a cooling zone and immediately solidified, and the take-up speed is soo~
Birefringence 900X10 to 700 by taking off at 5000 shoulders/min, preferably 1000 to 3500 m/min
0X1G, preferably 1200X10-5 to 600
0XIO-5 undrawn yarn at its cutting elongation of 80 seconds or more,
Preferably, it is produced by stretching 82 inches or more.

This stretching may be carried out continuously by spinning KM, or by winding the fiber once after spinning and then stretching, or by stretching at a cutting elongation of 80 or more in one stage, or by multi-stage stretching of two or more stages. Good too. In this stretching, the heating means (in the first stage of stretching when multi-stage stretching) is 250 to 650°C.
Preferably, a steam jet method in which heated steam at a temperature of 280 to 600° C. is ejected or a heated roller method at a temperature of 80 to 120° C. can be employed. Also, Sagi Shinryo IIK
The stress increment △L of the last 25 strands of elongation before cutting of the resulting fibers can be heat-treated accordingly to 0.41/d.
e or less and the dry heat shrinkage rate at 176°C to be 17cm or less, preferably 9 to 15%, (melting point of polyester -90°C) to (melting point of polyester -60°C)
It should be heat treated at a temperature of

In order to use the thus obtained polyester fiber of the present invention for reinforcing a rubber structure, it is formed into a bouquet according to a conventional method, applied with an adhesive, heat-treated, and then applied to the rubber structure.

In this case, the heat treatment temperature and degree of elongation are preferably adjusted so that the stress is 5 sqb or less, which is the maximum heat shrinkage stress of the polyester fiber before treatment. Therefore, it is preferable that the heat treatment after coding be carried out sufficiently at a temperature of 200 to 260° C. under elongation up to 20° C., usually for 30 to 240 seconds. By applying such heat treatment, the temperature is increased to exhibit the best performance, as will be clear from the following examples. That is, the heat-treated cord thus obtained has a strength of 5.51/do or more, a dry heat shrinkage rate of 4.5 seconds or less at 175°C, and an elongation of 4.5 mm under a load of 4.5 mm.
It has high strength, low shrinkage, and high modulus of 5- or less. In addition, the heat generation temperature in the rubber structure obtained by disposing and vulcanizing in rubber is significantly lower than that obtained from conventional rubber reinforcing polyester fibers, and the fatigue resistance is significantly improved. The rubber structure referred to in the present invention is, for example, a tire.

Natural rubber such as V-belts and conveyor belts.

Refers to all structures made of synthetic rubber, etc.

The polyester referred to in the present invention mainly refers to polyethylene terephthalate consisting of a terephthalic acid component and an ethylene glycol component, but it also refers to a polyester in which a portion of the terephthalic acid component, usually 10 mol or less, is replaced with another dicarboxylic acid component. It may also be a polyester in which a portion of the ethylene glycol component, usually 10 molar or less, is replaced with another diol component. Further, modifiers, stabilizers, additives, etc. may be optionally used in the overcast polyester as required.

The present invention will be further explained with reference to Examples below.

In addition, various measurements and traces in the examples are carried out by the following methods.

+11 Δn is a parameter indicating the degree of orientation of molecules in the filament, and was determined by the retardation method using Boomnaphthalene as the immersion liquid and a Perec compensator.

For a detailed explanation, please refer to Kyoritsu Shuppan's ``Polymer Experimental Course/Physical Properties of Polymers ■''.

(2) Load-back extension curve is JIS L 1017
-1963 (s, 4).

(3) Dry heat 175℃ shrinkage rate is JISL1017-1
963 (5, 12).

(4) Toughness and power utilization rate were calculated using the following formula.

Toughness - 1 strong force x V force ■ Strength utilization rate = - 1 strong force x 1 force x 100 drawn yarn strength x 2 (5) Tube heat generation temperature and tube life are JIS
Compliant with L1017-1963.1.3 LzIA Law.

However, the bending angle was 80'. The exothermic temperature is 90 at the start of operation.
After 11 minutes, check the temperature on the tube surface using an infrared non-contact thermometer (5A).
(manufactured by N-EI), and the tube life was expressed as the time until tube breakage.

Example intrinsic viscosity! , 05 polyethylene terephthalate (without titanium oxide content) was melted at about 290°C, and the pore size was 0.5.
After being discharged from a spinneret with 5 fins and 2509 holes, the discharged yarn is immediately cooled and solidified while blowing cooling air at 2S°C at 2.0 Nvrt/m, and then an oil agent is applied with an oil ruler and then guided to a take-up roller. Immediately after winding up, a 22 k&/d G steam jet thread interposed between the drawing rolls is sprayed at an angle of 45'' for stretching, or it is wound on a heating roll and then stretched for various purposes. At this time, the physical properties of the fox drawn yarn as a result of changes in the speed of the p-lar, the temperature of the steam jet, the stretching ratio, and the temperature of the stretching roll are shown in Table 1. The load-back extension curve of the drawn Utsugi yarn obtained in Experiment 8 is shown by curve (1) in the figure.

In Table 81, regarding the stretching temperature, SJ indicates the case where a steam jet is used, HR indicates the case where a heating roll is used, and L indicates the stress increment during the final 2.5-stretching before cutting. , and the intrinsic viscosity [ri] and birefringence △ of undrawn yarn
n is measured for an undrawn yarn that is wound up as it is without being drawn after being drawn by a take-up roller at room temperature.
The step wax stretching ratio can be determined by injecting a steam jet interposed between a take-up roller and a stretching roller, or by preheating with a heated roll, leading to a stretching roller, and gradually increasing the speed of the stretching roller to cut. It is expressed as the ratio (qb) of the stretching ratio to the maximum stretching ratio at the time.

Using each of the drawn yarns of the above examples, a cord was created by adding 49T/102 of first twist and then second twist, and then dry heat 2
The performance of the obtained treated cord is shown in Table 2.The tension ratio is determined according to the physical properties of the drawn yarn. The elongation was set to be 3.5%.

Comparative Example Polyethylene terephthalate (titanium oxide content: 0.07 cm) with an intrinsic viscosity of 1.01 was melted at about 300°C, and the pore size a
411111 After being discharged from a spinneret having 250 holes, it was immediately run in an atmosphere at a temperature of 335°C for 200 hours, then cooled and solidified while blowing 5.0 Nd1m of 25°C cooling air, and then passed through an oiling roller. After applying the oil agent, it is guided to a take-up roller rotating at a speed of 5 f 19 m/kil, and immediately after being rolled up, it is passed between a heating roller preheated to 100°C and a first rotation roller heated to 120°C. .1st JRjl: Stretched to 4 times, then stretched to 1.5 times between the stepped first rolling roller heated to 180°C, and then subjected to relaxation heat treatment for 3 times to 2910°C.
I turned it over with IN/111+.

The load-loading curve of the obtained fiber is shown in FIG. 1 by curve (2). At this time, the [ri] of the undrawn yarn is 0, 88, △n
was 350X1O.

The obtained performance is as follows.

Next, this drawn yarn was first twisted and then top twisted, 49 pieces, 710 clL each.
was added to create a cord, and then dry heat treated at 240° C. for 1 minute under tension. The performance of the obtained processing code is as follows.

[Brief explanation of the drawing]

The figure shows a load-loading curve, curve (t) ht is a load-loading curve of the polyester fiber of the present invention, and curve (2) is a load-loading curve of a conventional polyester fiber for reinforcing rubber structure. In the figure, p) is the cutting point, and ΔL is the stress increment during the last 2.5 inches of elongation before cutting. Elongation (96)

Claims (1)

[Claims] 11) Made of polyester whose main constituent unit is ethylene terephthalate, the load-stretching curve exhibits a positive slope at any point, and the stress increment during the last 2.5 inches of elongation before fracture is 0.411/d・or less and 175
A polyester fiber suitable for reinforcing rubber structures with a dry heat shrinkage rate of 17% or less at °C. (2) Cutting strength is 61/da or more 7.51//d
The polyester fiber according to claim 1, which has a molecular weight of less than o. (The polyester fiber according to claim 1 or 2, which has a dry heat shrinkage rate of 9 to 151 at 31175°C.