JPS6119812A - Polyester fiber - Google Patents

Abstract

PURPOSE:Polyester fibers that contains ethylene terephthalate as a major repeating unit and have specific values of intrinsic viscosity, elongation at break and crystallinity, thus showing a variety of good properties such as high strength, low shrinkage, high fatigue resistance, further having good drawability. CONSTITUTION:The objective fibers include ethylene terephthalate as a major repeating unit with an intrinsic viscosity of over 0.9, preferably 0.9-1.3 and elongation at break of less than 150%, preferably 150-40% and satisfy the equation [XX is crystallinity according to the X-ray wide angle diffraction; n is optical birefringence (higher than 0.06, preferably 0.06-0.14)]. Further, it is preferred that the crystal size is more than 50Angstrom and the dry heat shrinkage is less than 10% at 180 deg.C.

Description

Detailed Description of the Invention: a. Industrial Field of Application The present invention provides a polyester fiber that simultaneously has high strength, low shrinkage, and fatigue resistance characteristics as an industrial polyester fiber, and has good stretchability. The present invention relates to undrawn polyester fibers and fibers.

b. Prior art polyester fibers have various advantages. Because it has the characteristics,
It is widely used not only for clothing but also for industrial purposes. Polyester fibers, which have particularly high strength and excellent dimensional stability, are useful in industrial applications, and have been used not only for tires but also for industrial assets, but recently there has been a demand for a high level of mutually beneficial performance. For example, for tire cords, we need lower shrinkage to improve yield during tire molding, higher modulus to improve ride comfort, and improved fatigue resistance for large tires, while V-belt cords. As a cord for maintenance-free use, high modulus is required, and as a cord for large, high-load lap belts, high elongation, high toughness, and fatigue resistance are required1.From this perspective, cords with high strength, low shrinkage, and high modulus are required. If a polyester cord with fatigue resistance can be obtained, it will be used in an increasing number of fields due to its cost competitiveness with polyester fiber hook materials.

In particular, polyester fibers are inferior in modulus and shrinkage compared to older rayon fibers and vinylon fibers, and also significantly inferior in fatigue resistance compared to older general-purpose polyamide fibers. Improvements in these points are necessary. is important. If these points are improved, polyester fiber will be positioned more and more as an industrial fiber as it has superior cost and performance compared to rayon fiber, vinylon fiber, and polyamide fiber3. In order to develop high strength, K is
For example, Japanese Patent Publication No. 41-7892, Japanese Patent Publication No. 53-13
A method is known in which a high polymerization degree polyester as disclosed in Japanese Patent No. 67 is used, molecular orientation is suppressed in the spinning stage, and the stretching ratio is increased as much as possible in the stretching stage.

However, according to this method, since the degree of orientation of the amorphous molecular chains is high, high strength can be obtained, but on the other hand, the shrinkage rate also increases. On the other hand, in order to reduce the shrinkage rate, a method is known in which a low degree of polymerization polyester is used, for example as disclosed in JP-A-53-58028. However, with this method, it is difficult to obtain products with high strength and toughness. In addition, both of the above two methods yield products with low fatigue resistance.

In order to achieve low shrinkage and improve fatigue resistance, for example, Japanese Unexamined Patent Application Publication Nos. 53-58031 and 53-58032 recommend reducing the degree of molecular orientation in the drawing system and reducing work loss. Polyester fibers and methods for producing the same have been proposed with the aim of improving fatigue properties.

This method is characterized by rapid cooling in a gas atmosphere of 10 to 60°C under a spinneret, but the degree of elongation is extremely small because the yarn is stretched to the point of cutting to achieve high strength. It has the disadvantage that thread breakage occurs frequently and stable production is difficult.

Means for Solving the C1 Problem The inventors of the present invention, in an attempt to eliminate such drawbacks, have made intensive studies and found that a crystalline undrawn fiber with a specific degree of polymerization and a higher degree of It has been found that by using undrawn fibers that have sufficient cross-cut elongation while having orientation, a drawn system or cord with good drawability and desired properties can be obtained. That is, we have discovered that it is possible to stably produce polyester fibers that have high strength, high elongation, low shrinkage, and good fatigue resistance, and provide cords suitable for industrial use. We have arrived at the present invention.

That is, the present invention relates to a polyester fiber containing ethylene terephthalate as a main repeating unit, having an intrinsic viscosity of 0.9 Jd or more, having a breaking elongation of 150% or more, and satisfying the following formula %. .

The polymer constituting the polyester fiber of the present invention is a polyester containing 90 moles or more, preferably 95 moles or more of ethylene terephthalate repeating units in the molecular chain. Polyethylene terephthalate is preferred as such polyester, but less than 10 moles 5, t! In other words, it may contain other copolymer components in a proportion of less than 5 molar. Examples of such copolymerization components include isophthalic acid, naphthalene/dicarboxylic acid, adipic acid, oxybenzoic acid, diethylene glycol, propylene glycol, trimellitic acid, and pentaerythritol. Furthermore, these polyesters may contain additives such as stabilizers, colorants, and the like.

The undrawn polyester fiber of the present invention needs to have an intrinsic viscosity of 0.90 or more as determined from a 25° COC coulophenol solution.

If the intrinsic viscosity is less than 0.90, a high-strength polyester cord cannot be obtained. Intrinsic viscosity is 0.9 to 1.3
is preferred.

The undrawn polyester fiber of the present invention needs to have an intrinsic viscosity of 0.90 or more as determined from a 0-chlorophenol solution at 25°C.

If the intrinsic viscosity is less than 0.90, a high-strength polyester cord cannot be obtained. The intrinsic viscosity is preferably 0.9 to 1.3.

One polyester undrawn fiber of the present invention needs to be crystalline. If it is not crystalline, it will not be possible to obtain the low shrinkage properties of rayon fibers and vinyl fibers. Here, whether or not there is collusion is detected by whether diffraction butter/ appears in the X-ray wide-angle diffraction pattern. Note that the crystallinity and crystal size were determined by the following method from X-ray wide-angle diffraction.

Crystallinity Degree of crystallinity was calculated using the plate pressure method using the profile obtained by rotating the sample in a plane perpendicular to the incident X-rays and the profile obtained by scanning the sample in the meridian direction Vζ while the sample was fixed.

Crystal size was determined using the Scherrer equation from the half value of the (010)(100) intensity distribution curve of equatorial line scanning.

The fiber of the present invention has sufficient cutting elongation while being crystalline.
That is, it is necessary to have a cutting elongation of 150% or less. In general, the K used to manufacture industrial polyester fibers is undrawn fiber with a high elongation of over 150%, which is undrawn, and has a high elongation of over 150%. It was considered suitable for obtaining. However, as mentioned above, although high strength can be obtained, a polyester cord with low shrinkage rate and good fatigue resistance cannot be obtained.

To obtain a polyester that has at least the desired strength for industrial use, low shrinkage rate, and extremely good fatigue resistance; It is necessary to subject it to stretching. Cutting elongation is 1
50% or less and 40% or more are preferable because stretchability is good.

As mentioned above, the undrawn fiber of the present invention must be crystalline and have a specific cutting elongation, and the degree of crystallinity and degree of orientation, which are correlated with each other, must satisfy the following relationship.

Xx=2.4X10'XΔm+4 Here, Xx is the crystallinity determined by X-ray wide-angle diffraction, and was calculated by the method described above.

Further, the delta deviation is a birefringence index, which is measured using a Bereck convenser attached to a polarizing optical microscope, and the birefringence index must be 0.06 or more. If the birefringence is less than 0.06, it is difficult to significantly improve low shrinkage and fatigue resistance, and it is preferably 0.06 or more.
14 or less.

The undrawn fiber of the present invention has good drawability only when it satisfies the above relationship between crystallinity and birefringence, and when a cord is made from the obtained drawn fiber, the desired high strength, low shrinkage, and resistance can be obtained. This is an essential condition for obtaining a product with excellent fatigue resistance.

Preferably, the undrawn fiber of the present invention has a crystal size of 50A or more calculated by the method described above and has moderately developed crystals, and further has a dry heat shrinkage rate of 10% or less at 180°C. It is particularly preferable to have a low shrinkage rate. In addition, the dry heat shrinkage rate at 180℃ is JIS
Calculated according to the method described in L1017-1963 (5, 12).

The undrawn fiber of the present invention can be obtained, for example, by the following method. Polyester containing ethylene terephthalate as a main repeating unit and having an intrinsic viscosity of 0.95 to 1.5, or a polyester having an intrinsic viscosity of 0.95 to 1.5.
7 to 0.9 polyester is reacted with a degree of polymerization accelerator, melted and transported by a conventional method, and discharged from a spinneret into a yarn so that the fineness after drawing becomes 1 to 20 da, and immediately after discharge, it is rapidly cooled. Alternatively, the material is kept at a temperature below the melting point and up to the crystallization initiation temperature, or delayed cooling is performed by exposing it to a heated atmosphere at a temperature above the melting point for a certain period of time. Thereafter, it is cooled and solidified in a filamentous manner, and it is useful to cool and solidify it under the following conditions.

Next, after cooling and solidifying as described above, the oil agent was applied and then 3
Pick up at a speed of 000 m/min or more.

For example, one-way oil application is done using an oiling roller.

Any method such as a one-way spray method is possible.

Further, as the oil agent, any textile oil agent can be applied as necessary. At this time, in fields where adhesion with rubber is important as a fiber application, it is useful to apply a surface treatment agent to impart adhesion.

By selecting the above conditions as needed, the intrinsic viscosity becomes 0.
．． A crystalline undrawn fiber having a cutting elongation of 90 or more and a cutting elongation of 150 or less, and a crystallinity Xx and a birefringence Δn of Xx=2.
The relationship of 4X10'X△n+4 is satisfied, and the birefringence is 0.
06 or higher can be obtained.

In the present invention, the undrawn fibers having the above-mentioned characteristics taken at a speed of 3000 rr+/min or more may be drawn continuously after spinning, or may be drawn in a step after being wound once. When the spinning is followed by continuous drawing, it can be carried out in accordance with the method described in Japanese Patent Application No. 57-88927 previously proposed. In addition, when the yarn is wound up once after spinning and then stretched, it is possible to
This can be carried out in accordance with the method described in Japanese Patent No. 89094. The latter stretching method is preferred in terms of reducing stretching strain during stretching and heat treatment strain. That is, the undrawn fiber is Tg+1
7 of the total draw ratio after preheating for at least 0.5 seconds at a temperature of 5 to Tg + 50°C (where 'rg is the glass transition temperature of the fiber).
The first stage of drawing is performed at a factor of 5 or less to give a birefringence of 1.2 to 3.3 times the birefringence of the undrawn fiber. Next, the single-stage drawn yarn is further subjected to multi-stage drawing heat treatment. At this time, when high strength is required such as a 9-year reinforcing cord, the final tension heat treatment is carried out at a constant length or 5. With a tension level of %,
Preferably a constant length or a tension of up to 2.5 tension of 0.4 to 1
．． It is better to hold it for 5 seconds. Also, for cords for large, high-load rasped belts that have high elongation and require toughness, the melting temperature of the fiber after the first stage of stretching should be from -50°C to -3). The second stage stretching was performed in the range of 0°C, and the total stretching ratio was reduced to 85, which was the cutting stretching ratio.
It is preferable to keep it below the limit.

Furthermore, in industrial applications where stretched ## is used as it is without being coated, the melting temperature of multi-stage stretching heat treatment is -50°C.
It is preferable to carry out a relaxation heat treatment at a temperature of 0.4 to 1.5 seconds at a melting temperature of -3) 0.degree.

The drawn polyester fiber obtained by the above method has a strength of 6.0. ! i'/de or more, elongation is 10 or more 1
80℃ dry heat shrinkage rate is 8.5 or less Amorphous orientation degree is 0.64
The characteristics of the long cycle period floor being 16OA are shown below. Such polyester fibers are used for industrial purposes either as they are after being knitted or woven, or after being heat treated. At this time, the excellent fiber properties are expressed as they are and are extremely effective. Alternatively, it can be made into a cord according to a conventional method, applied with an adhesive, heat-treated, and applied to a rubber structure. Note that the term "rubber structure" refers to all structures made of natural rubber or synthetic rubber, such as tires, hoses, belts, and conveyor belts.

d. Examples The present invention will be explained in further detail with reference to Examples below. Note that all parts in the examples indicate parts by weight.

Male side: 97 parts of dimethyl terephthalate, 6 parts of ethylene glycol
9 parts of Carnow Al acetate hydrate, and 0.025 parts of antimony trioxide were charged into an autoclave, and methanol produced as a result of transesterification was removed at 180 to 230°C while slowly passing nitrogen through, and then HsPO
Add 0.05 part of 50% aqueous solution of a and raise the heating temperature to 28.
While raising the temperature to 0°C, the pressure was gradually reduced to 0.2 mm/g in about 1 hour, and the polymerization reaction was continued for 1 hour and 50 minutes to obtain an intrinsic viscosity of O, SO.

A polymer having a terminal carboxyl group weight of 28 equivalents/10 grams was obtained.

100 parts of this polymer chip was triblended with 2,2'-bis(2-oxazoline) (cE) in the amount shown in Table 1, and then melted and transported at about 300°C, with a pore diameter of 0.6 mm and a number of pores of 2.
After being discharged from a spinneret having 50 yarns, the discharged yarn was maintained under the cooling conditions listed in Table 1, and then 25°C cooling air was applied to the yarn for 30 minutes.
After cooling and solidifying while blowing 4.0 Nd over a thickness of 0 mm for 1 minute, an oil agent was applied with an oiling roller and the film was rolled up at the take-up speed shown in Table 1. The properties of the obtained undrawn fibers are shown in Table 1.

This undrawn fiber is heated to 85°C and supplied to the next roll,
between the take-up roll and the first one at the magnification (DR,) listed in Table 1.
After stage stretching, a second stage stretching was carried out at the magnification (DR,) shown in the table through a gas bath heated to 325°C. Thereafter, tension heat treatment was carried out at the magnification DR as described in the table, with or without using a heating roller at 130°C and a gas bath at 330°C as described in the table. The performance of the obtained drawn yarn is also listed in Table 1.

Next, some of these drawn yarns were given two twists of 490 turns/m, and then the two were combined to give an S twist of 490 turns/m to form two 1000 deX raw foods. This raw food was immersed in an adhesive (RFL liquid) and subjected to tension heat treatment at 245° C. for 2 minutes.

The characteristics of this processing hood, tube fatigue resistance, and heat resistance strength were measured by embedding it in rubber and vulcanizing it. The results are also listed in Table 1.

Note that the characteristic values of the processing hood were measured by the following method.

(3) The load-loading curve is JISL1017-1963 (
(2) Dry heat 175℃ shrinkage rate is JISLIO17-1
963(5,12).

(3) Tube life is JISL1017 = 196
3.1.3.2. Compliant with IA law. However, the bending angle is 9
It was set to 0°.

(4) For heat resistance and strength, the chemical coat was immersed in RFL adhesive solution and heat treated at a tension of 1245° C. for 2 minutes. This treated cord was embedded in a vulcanization mold and accelerated vulcanization was carried out at 170° C. and a pressure of sokg/d for 120 minutes.The treated cord was then taken out and its strength was measured.

Procedural amendment September 0, 1980

Claims (3)

[Claims] (1) Made of polyester whose main repeating unit is ethylene terephthalate and whose intrinsic viscosity is 0.9 or more, whose elongation at break is 150% or less, and whose formula is as follows: Xx=2.4×10^2×
A polyester fiber that satisfies the following: Δn+4 [where Xx is the crystallinity determined by wide-angle X-ray diffraction Δn is the birefringence index of 0.06 or more]. (2) The polyester fiber according to claim 1, which has a crystal size of 50 Å or more. (3) The polyester fiber according to claim 1 or 2, which has a dry heat shrinkage rate of 10% or less at 180°C.