JPS6269819A - Polyester fiber - Google Patents

Abstract

PURPOSE:To provide the titled fiber composed of a polyester consisting of ethylene terephthalate unit and having a specific viscosity, having specific orientation degree of amorphous part and crystal melting point, high strength, low shrinkage and excellent fatigue-resistance and drawability and useful as an industrial material. CONSTITUTION:For example, a polyester containing ethylene terephthalate as a main recurring unit and having an intrinsic viscosity of 0.9-1.5 is melt-spun and cooled slowly in an atmosphere heated above the melting point of the polyester. The cooled polyester yarn is further cooled and solidified under the condition of formula (X is distance between the spinneret and the blasting surface of the cooling air stream and is <=450mm; y is blasting length of the cooling air stream and is 100-500mm; Q is rate of blasting of the cooling air and is 2-6Nm<2>/min). The solidified yarn is oiled and taken up to obtain the objective fiber having an amorphous orientation degree of 0.3-0.55 and a crystal melting point of 265 deg.C and composed of a polyester containing ethylene terephthalate as a main recurring unit and having an intrinsic viscosity of >=0.9.

Description

[Detailed description of the invention] a. Technical field The present invention has high strength and is useful as an industrial material.

The present invention relates to a polyester fiber that has low shrinkage, good fatigue resistance, and good stretchability.

b. Prior art Because polyester fibers have various excellent properties, they are widely used not only for clothing but also for industrial purposes. Polyester fibers have particularly high strength and excellent dimensional stability.
They are useful in industrial applications and are increasingly being used not only in tire applications but also in property applications, both of which are now required to have a high degree of performance. For example, in conveyor belt and rubber hose applications, dimensional stability during molding requires lower shrinkage, durability under harsh usage conditions, and fatigue resistance. In addition, for tire cords, we need lower shrinkage to improve retention during tire molding, higher modulus to improve riding comfort, and improved fatigue resistance for use with large tires. Cords for belts are required to have high modulus to be maintenance-free, and cords for large, high-load lap belts are required to have high elongation, high toughness, and fatigue resistance. From this perspective, if a polyester cord with high strength, low shrinkage, high modulus, and fatigue resistance can be obtained, polyester fibers will be used in more and more fields due to their cost competitiveness with other materials.

In particular, polyester fibers are inferior in modulus and shrinkage compared to rayon fibers and vinylon fibers, which have a long history, and are significantly inferior in fatigue resistance compared to general-purpose polyamide fibers, which have a long history. Improvement is important.

If these points are improved, polyester fiber will be positioned as a material for industrial use as a fiber with better cost/performance than rayon fiber, vinylon fiber, and polyamide fiber.

In order to achieve the high strength required for industrial fibers,
For example, Japanese Patent Publication No. 41-7892, Japanese Patent Publication No. 53-13
A method is known in which a high degree of polymerization polyester is used as disclosed in Japanese Patent No. 67, molecular orientation is suppressed in the spinning stage, and the stretching ratio is increased as much as possible in the stretching stage. However, with this method, it is difficult to obtain products with high strength and toughness. Furthermore, in order to reduce the shrinkage rate,
As disclosed in Japanese Patent No. 51524, a method is known in which multistage stretching is followed by heat treatment at high temperature and low tension. However, like the above two methods, this method also provides only a product with low fatigue resistance.

In order to achieve low shrinkage and improve fatigue resistance, for example, Japanese Patent Application Laid-open Nos. 53-58031 and 53-58032 disclose that the degree of molecular orientation of drawn yarn is reduced and the work loss is reduced to improve durability. Polyester cords and methods for manufacturing 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.

C1 Purpose of the Invention The present inventor provides a polyester fiber for property use that has high strength, low shrinkage comparable to rayon and vinylon, fatigue resistance superior to rayon and vinylon, and has good drawability. As a result of careful consideration,
We have discovered that high strength, low shrinkage, good fatigue resistance, and good stretchability can be achieved only when the amorphous portion and crystalline portion are in a specific state with a specific degree of polymerization, and have arrived at the present invention. It is.

d3 Structure of the invention, that is, the present invention is made of polyester having ethylene terephrate as a main repeating unit and having an intrinsic viscosity of 0.9 or more, an amorphous orientation degree of 0.3 to 0.55, and a crystalline melting point of 265.
To provide a polyester fiber having a temperature of at least ℃.

FIG. 1 is a graph showing temperature-shrinkage rate curves of some fibers obtained in Examples and Comparative Examples of the present invention.

FIG. 2 is a graph showing a temperature-thermal stress curve of some fibers obtained in an example of the present invention.

The polymer constituting the polyester fiber of the present invention contains 90 mol% of ethylene terephthalate repeating units in the molecular chain.
As mentioned above, polyester preferably contains 95 mol% or more. Polyethylene terephthalate is suitable as such polyester, but it contains less than 10 mol%, preferably 5
Other copolymer components may be included in a proportion less than mol %. An example of such a copolymer component is isophthalic acid.

Examples include naphthalene dicarboxylic acid, adipic acid, oxybenzoic acid, diethylene glycol, propylene glycol, trimellitic acid, and pentaerythritol. These polyesters may also contain additives such as stabilizers and coloring agents.

The 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 polyester fiber with high strength while maintaining low shrinkage and fatigue resistance cannot be obtained. The limiting viscosity is preferably 0.9 to 1.3.

The degree of amorphous orientation specified in the present invention is mainly related to the shrinkage rate and strength of the drawn fibers obtained. In the fiber of the present invention, the degree of amorphous orientation is 0.30 to 0.55, preferably 0.3
It is in the range of 5 to 0.50. If this value exceeds 0.55, the desired shrinkage rate cannot be obtained, while if it is less than 0.30, sufficient strength for the intended use cannot be obtained.

Further, the crystal melting point is related to the remaining strength when the obtained drawn m-fiber is subjected to high temperature treatment (dry heat or wet heat) as it is or after being formed into a fabric. In IjltM of the present invention, the crystal melting point is 265°C or higher, preferably 270°C or higher. If the temperature is less than 265°C, the strength will deteriorate significantly during high-temperature treatment, making it impractical.

The polyester 1ef of the present invention is preferably 4.0×
It has a crystal volume of 10×105 Å3 or more. If the crystal volume is less than 4, OX 10 x 105 Å3, when the polyester fiber is subjected to heat treatment in a post-processing step after weaving, for example, strength deterioration tends to occur, which is inappropriate.

The polyester m fiber of the present invention is also preferably 210
Dry heat shrinkage rate at °C is 6% or less, more preferably 4%
It is as follows. The dry heat shrinkage rate is related to the shape stability during high temperature treatment when the drawn fiber is used as it is or after being formed into a fabric. If it exceeds 6%, this morphological stability is poor, and in the case of fabric, it becomes wrinkled, resulting in poor quality and post-processability.

The fiber of the present invention further preferably has a weight of 10 g/de or less,
More preferably, it has a terminal modulus of 9 g/de or less. Terminal modulus is related to the residual strength during twisting when drawn fibers are used in a twisted state.

If this value exceeds 10 g/de, the strength loss during twisting will be large and it will be necessary to unnecessarily increase the strength of the drawn fibers.

In the polyester fiber of the present invention, it is preferable that the amorphous portion simultaneously satisfies the following conditions (1) to (4) from the temperature dispersion behavior of the mechanical loss modulus.

■ The half value width of the main component that appears in the temperature dispersion of the mechanical loss modulus is 45°C or less.

■The peak temperature of the main dispersion is 125°C or less.

This half width indicates the distribution of the degree of amorphous orientation in the amorphous region, and it can be said that the smaller the half width, the smaller the distribution.

If the half width exceeds 45°C, stress concentration occurs on specific molecular chains in the amorphous region when stress is applied to the fibers, making the molecular chains easy to break, resulting in poor fatigue resistance and is therefore unsuitable. Furthermore, the peak temperature of the main fraction indicates the degree of molecular orientation in the amorphous region, and it can be said that the lower the peak temperature, the lower the degree of orientation. If the peak temperature exceeds 125° C., the degree of orientation is high and the strength is high, but it is not possible to simultaneously satisfy low shrinkage and fatigue resistance.

Although the polyester fiber of the present invention does not have a very high degree of amorphous orientation, it has a long molecular chain length expressed by the intrinsic viscosity, has a low distribution of the degree of amorphous orientation, and has the desired strength due to the balance with the crystalline portion described below. It has both excellent shrinkability and fatigue resistance.

Further, the fibers of the present invention preferably have a long period spacing of 160 Å or more.

The fibers of the present invention also preferably have a specific fiber structure due to amorphous and crystalline parts. That is, the thermal stress curve has thermal stress peaks in each of the temperature ranges of 100 to 180°C and 180°C or higher (see FIG. 2). The former thermal stress peak is associated with the amorphous portion of the fiber structure, and the latter thermal stress peak is associated with the crystalline portion.

The polyester fiber of the present invention has a strength of 6.0 g/de or more, which is sufficient for industrial uses, and an elongation of 10% or more, preferably 20% or more, which shows high toughness and high durability.

The polyester fiber of the present invention can be obtained, for example, by the following method.

Polyester containing ethylene terephthalate as the main repeating unit and having an intrinsic viscosity of 0.95 to 1.5 or an intrinsic viscosity of 0
．． 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 yarn so that the fineness after drawing is 1 to 20 de and the total denier is 500 to 200 de, Immediately after discharge, it is rapidly cooled, but it is kept warm at a temperature below the melting point and up to the temperature at which crystallization begins, 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, the yarn is cooled and solidified, and it is useful to cool and solidify it under the following conditions.

400≦(xxf'')/Q≦1900 [X is the distance from the spinneret surface to the blowing surface of the cooling air (room temperature) and is 450 Im or less, y is the blowing length of the cooling air and is 10
0-500InIR9Q has a cooling air blowing amount of 2-6N.
yd/min, 1 Then, after cooling and solidifying as described above, the oil agent was applied and then taken off at a speed of 3000 m/min. The oil can be applied by any method such as an oiling roller method or a spray method. Further, as the oil agent, any textile oil agent can be applied as needed. At this time, in fields where adhesion with rubber is important as a use of l11M, 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 with a cutting elongation of 90 or more and a cutting elongation of 150% or less, with a crystallinity XX and a birefringence △n of X 2.4x
102 xΔn+4 Here, XX is the degree of aggregation Δn determined by X-ray aperture angle diffraction, and the birefringence satisfies the relationship of 0.06 or more, and an undrawn fiber with a birefringence of 0.06 or more is obtained.

In addition, such undrawn fibers have a draft rate of 300 to 1000, an orifice diameter of 0.55 to 2.5M11, and a take-up speed of 2000 to 1000. It can also be obtained by setting the rate to 6000TrL/min. Here, the draft rate is the ratio of the fiber take-up speed to the polymer discharge linear speed (orifice exit speed).

In the present invention, the undrawn fibers having the above-mentioned properties taken at the above-mentioned speed may be drawn continuously after spinning, or may be drawn in a separate step after being wound up once. When the spinning is followed by continuous drawing, it can be carried out in accordance with the method proposed earlier in Japanese Patent Application No. 88927/1983. In addition, when the yarn is wound up once after spinning and then stretched,
This can be carried out in accordance with the method proposed earlier in Japanese Patent Application No. 189094/1982. The latter stretching method is preferred in terms of reducing stretching strain during stretching and heat treatment strain. That is, after preheating 1g of undrawn I fiber at +15~T(]+50°C (here, Tg is the glass transition temperature of the fiber) for at least 0.5 seconds, the first step is drawn at a draw ratio of 75% or less of the total draw ratio. The birefringence is set to 1.2 to 3.3 times the birefringence of the undrawn fiber.The single-stage drawn yarn is then further heat-treated in multiple stages.

At this time, in industrial applications where the drawn fibers are used as they are without being coded, the melting temperature of the fibers after multi-stage drawing is -50°C.
It is preferable to carry out a relaxation heat treatment of 10 to 20% while maintaining the melting temperature for 0.4 to 1.5 seconds in the range of −110° C. to melting temperature.

The polyester fibers obtained in this way are used as is after knitting or weaving or after being heat-treated for use in assets. At this time, the excellent fiber properties are expressed as they are,
It is clearly effective. In addition, according to common law, the code and
It can also be applied to rubber structures by applying an adhesive and heat treating. Note that the rubber structure is, for example, a hose, ■-
belt.

Refers to all structures made of natural rubber or synthetic rubber, such as conveyor belts. In particular, the Y& fiber of the present invention is useful as a weft of a rubber reinforcing fabric, a reinforcing material for a resin hose or a rubber hose, an electrical insulating material (1), a belt reinforcing material (2) for heavy weight, (2) a resin reinforcing material, and an optical fiber reinforcing agent.

The characteristics cited in the present invention were measured by the following methods.

■ The degree of amorphous orientation fa is determined by Robert J. Saminil (R
J. Obert, J., Samuel) method of writing a paper (J., Polymer Science
A 2, 10.1972).

That is, △n =Xfc△nc+ (1-X) faΔna
Here, Δn is a parameter indicating the degree of orientation of molecules in the filament, and was determined by the retardation method using bromonaphthalene as the immersion liquid and a Pellec convensator. Detailed explanation is available at Imori Publishing [Polymer Experimental Course/
Please refer to Physical Properties of Polymers (■).

fc is the degree of crystal orientation and was determined by a conventional method from the average orientation angle θ measured by mouth angle X-ray diffraction.

X is the degree of crystallinity, which was determined from the density using a conventional method.

△nc and △na are crystalline and amorphous intrinsic birefringences, and for polyethylene terephthalate, they are 0.220° and 0.27, respectively.
It is 5.

(2) The crystal melting point was measured using a PerkinElmer Model DSC-1 at a heating rate of 20° C./min, and the endothermic peak value was taken as the crystal melting point.

■ 210℃ dry heat shrinkage rate is JIS L 1017
- Compliant with 1963 (5, 12).

■Crystal volume = crystal size in a-axis direction x crystal size in b-axis direction x periodic interval x crystallinity, where crystal size is (010) Find the half value of the interference peak of the (100) plane and use Scherrer's equation. Calculated.

The degree of crystallinity was calculated by Sakurada and Natsushinakata.

(2) The value obtained by dividing the stress increment on the load-elongation curve of the terminal modulus fiber by subtracting 2.4% from the cutting elongation by 2.4X10-2.

The load-extension curve is J) 3 11017-1963 (
5, 4).

■ Mechanical loss modulus The mechanical loss modulus is 0.25 for a sample of length 3α using a spectrometer VES=F type manufactured by Iwamoto Seisakusho.
frequency 10 with an amplitude of 0.17% with a g/de load applied.
Measured under conditions of HZ and temperature increase rate of 1.6° C./min. The half width of the main component is the peak temperature 1 which indicates 1/2 of the peak value of the main component.

■ The long-period long-period interval was measured using a conventionally known method using a small-angle X-ray scattering measurement device, that is, using CuKα rays of wavelength 1.54 as a radiation source.
Diffraction lines of afternoon ray interference obtained by irradiating at right angles to the lI fiber axis were calculated using Bragg's equation.

(2) Thermal Stress Curve The thermal stress curve was measured using a conventionally known manufacturing method at an initial load of 50 g and a temperature increase rate of 4° C./min.

The present invention will be explained in further detail by referring to Examples below.

Note that all parts in the examples indicate parts by weight. The characteristic values of the treated cord were measured by the following method.

(1) The load-stretching curve is L I S L 1017
- Compliant with 1963 (5, 4).

(2) Chief L 101
7-1963゜1.3.2. Compliant with IA law. However, the bending angle was 90°C.

(3) For heat resistance, the raw cord was immersed in RFL adhesive solution and heat treated at 245°C for 2 minutes under tension. Embed this processing cord in a vulcanization mold at 170°C and a pressure of 50°C.
After accelerated vulcanization with ci for 120 minutes, the treated cord was taken out and its cooperation was measured.

Example 1 97 parts of dimethyl terephthalate, 6 parts of ethylene glycol
9 parts of calcium acetate monohydrate, and 0.025 parts of antimony trioxide were placed in an autoclave, and the methanol produced as a result of transesterification was removed at 180-230°C by slowly passing nitrogen through the autoclave. Add 0.05 part of a 50% aqueous solution, raise the heating temperature to 280°C, gradually reduce the pressure, and heat for about 1 hour at 50°C.
The partial polymerization reaction was continued to obtain a polymer having an intrinsic viscosity of 0.80 and a terminal carboxyl group weight of 28 equivalent rJ/10 G gram polymer.

100 parts of this polymer chip was triblended with 2,2'-gos(2-oxazoline>(CE)) in the amount shown in Table 1, and then melted and transported at about 300°C.
After being discharged from a spinneret having 250 holes, the discharged yarn was maintained under the cooling conditions listed in Table 1, and cooled and solidified while blowing cooling air at 25°C over 300M at 4ONTrL3/min. After applying an oil agent with an oiling roller, the tube 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 unstretched IMI [is supplied to a roll heated to 85°C, and after the first stage stretching is performed between it and a take-up roll at the ratio (DR+) listed in Table 1, it is passed through a gas bath heated to 325°C. Second stage stretching was carried out at a magnification of 100 mL (DR2). Then 130℃
Tension heat treatment was carried out at a magnification of SR3 according to the number indicated, with or without using a heating roller at 330°C and a gas bath at 330°C as indicated.

The performance of the obtained drawn yarn is also listed in Table 1.

Next, some of these drawn yarns were given 7 twists of 490 turns/IIl, and then two of these were combined and given S twists of 490 turns/m to form two raw cords of 1000 dex.

This raw cord was immersed in adhesive (RFL liquid) and heated to 245°C.
The sample was subjected to tension heat treatment for 2 minutes. The characteristics of this treated cord, as well as tube fatigue resistance and heat resistance strength after embedding it in rubber and vulcanizing it, were measured. The results are also listed in Table 1.

(Left below) Example 2 In Example 1, 2,2'-bis(2-oxazoline)
Same as Example 1 except that the amount of addition was 0.15 wt%, the hole diameter was 1.50 M, the length of the heat insulating cylinder on the cap was 100 #, the insulating temperature was 230°C, the cooling air blowing distance was 1201 M, and the take-up speed was 2500771/min. The following undrawn fibers were obtained in the same manner.

Intrinsic viscosity: 0.92 Terminal carboxylic group concentration: 8.0 per ton Birefringence
0.0707 Crystallinity 28.4
%, then the unstretched mu is DR+ = 1.3,
The following drawn fibers were obtained in the same manner as in Example 1 except that DRz = 1.50 and DR3 = 1.05.

Fineness 1005 de strength
7.4 g/de elongation
10.1% long period 1
65 people 210℃ dry heat shrinkage rate 5.1
%Melting point 273℃Crystal volume
5,3x 10x105Å3 Degree of amorphous orientation 0. 50 Furthermore, the physical properties of the obtained dip cord were as follows.

Powerful 14. OK94.5Kg load elongation 3.5% cutting elongation
15.2% 175℃ dry yield
2.3% Heat resistance strength retention rate 67%
Example 3 97 parts of dimethyl terephthalate, 6 parts of ethylene glycol
9 parts of calcium acetate monohydrate, 0.034 parts of antimony trioxide, and 0.025 parts of antimony trioxide were placed in an autoclave, and methanol produced as a result of transesterification was removed at 180 to 230°C while slowly passing nitrogen.
Add 0.05 part of 50% aqueous solution of O4 and raise the heating temperature to 28.
While raising the temperature to 0°C, the pressure was gradually reduced, and it took about 1 hour to reduce the pressure of the reaction system to 0.2 mInHLJ, and the polymerization reaction was continued for 1 hour and 50 minutes, resulting in an intrinsic viscosity of 0.80 and a terminal carboxyl group weight of 28. A weight of 10G/10G polymer was obtained.

100 parts of this polymer chip was triblended with 2,2'-bis(2-oxazoline) (CE) in the amount shown in Table 2, and then melted and transported at about 300°C, with a pore size of 0.6. After being discharged from a spinneret having 250 holes, the discharged yarn is passed through a second spinneret.
After cooling and solidifying while blowing the cooling air listed in the table at 300 tones for 4, ONm and 37 minutes, oiling roller
An oil agent was applied thereto, and the film was rolled up at the take-up speed shown in Table 2. The properties of the obtained undrawn fibers are shown in Table 2.

This undrawn fiber is supplied to a roll heated to 85°C,
between the take-up roll and the first one at the magnification (DRl) listed in Table 2.
After the stage stretching, a second stage stretching was carried out at the magnification (DR2) shown in the table through a gas bath heated to 325°C. After that, using a heating roller at 130℃ and a gas bath at 330℃, the magnification is O as specified in the table.
Relaxation heat treatment was performed at R3.

The performance of the obtained drawn yarn is also listed in Table 2.

[Brief explanation of drawings]

FIG. 1 is a graph showing temperature-shrinkage rate curves of some fibers obtained in Examples and Comparative Examples of the present invention;
The figure shows some results obtained in the embodiments of the present invention! It is a graph showing a temperature-thermal stress curve of IN.

Claims (1)

[Scope of Claims] 1. A polyester containing ethylene terephthalate as a main repeating unit and having an intrinsic viscosity of 0.9 or more, an amorphous orientation degree of 0.3 to 0.55, and a crystalline melting point of 265°C. fiber. 2. The polyester fiber according to claim 1, which has a crystal volume of 4.0×10^5 Å^3 or more. 3. The polyester fiber according to claim 1 or 2, which has a dry heat shrinkage rate of 6% or less at 210°C. 4. The polyester fiber according to any one of claims 1 to 3, which has a terminal modulus of 10 g/de or less; ℃ or less Claim 1~
The polyester fiber 6 according to any one of claim 4, and the polyester fiber according to any one of claims 1 to 5, wherein the long period interval is 160 Å or more. 7. Made of polyester containing ethylene terephthalate as the main repeating unit and having an intrinsic viscosity of 0.9 or more, having a breaking elongation of 150% or less, and having the following formula: Xx=2.4×10^2×Δn+4 (wherein, Xx is Crystallinity by wide-angle X-ray diffraction, Δ
n is a birefringence index of 0.06 or more. 7. The polyester fiber according to any one of claims 1 to 6, which is obtained by drawing a polyester fiber that satisfies the following conditions and then heat-treating it under tension of 20 to 20%. 8. The polyester fiber according to any one of claims 1 to 7, wherein the half value width of the main dispersion appearing in the temperature dispersion of the mechanical loss modulus is 45°C or less. 9. The polyester fiber according to any one of claims 1 to 8, which has thermal stress peaks in the temperature ranges of 100 to 180°C and 180°C or higher, respectively, in the thermal stress curve.