JPS61132616A - Polyester fiber - Google Patents

Abstract

PURPOSE:To provide a polyethylene terephthalate polyester fiber having specific intrinsic viscosity, long-period spacings and crystal melting point, having high modulus, low shrinkage and excellent fatigue resistance, and suitable as a tire cord. CONSTITUTION:The objective polyster fiber is composed mainly of ethylene terephthalate units, and has an intrinsic viscosity of >=0.90, preferably 0.9-1.3, a long-period spacing of >=160Angstrom , and a crystal melting point of >=270 deg.C. Prefer ably, the volume of the crystallite is >=4.5X10<5>Angstrom <3>, the orientation degree of the amorphous region is <0.55, and the breaking strength of the fiber is >=6.0g/de.

Description

[Detailed Description of the Invention] a. Industrial Application Fields Polyester fibers have various excellent properties;
It is widely used not only for clothing but also for industrial purposes. Polyester a with particularly high strength and excellent dimensional stability
isi is useful for industrial applications, not only for tire applications.
Although it is also used for property applications, recently more and more advanced performance is required. For example, for tire cords, it is necessary to improve the yield during tire molding, to increase the modulus to reduce shrinkage and improve riding comfort, and to improve fatigue resistance for use in large tires. On the other hand, cords for V-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 can be obtained that has the lowest shrinkage, high modulus, and fatigue resistance of any polyester fiber in history, it will be used more and more because of its cost competitiveness with other materials. The number of fields covered will increase. In particular, polyester JIN has inferior modulus and shrinkage compared to older rayon fibers and Japanese fibers, and is also significantly inferior in fatigue resistance compared to older general-purpose polyamide fibers. Important 1゜If this point is improved, polyester fibers will be cheaper than rayon fibers, vinylon fibers, polyamide fibers, etc.
Its position as an industrial fiber with excellent performance is increasing.

b. Prior Art Recently, polyester TiM has been widely used, for example, in tire cord applications, mainly as a carcass material for radial tires. In particular, for example, JP-A-53-580
As proposed in Publication No. 32, a tire cord using undrawn yarn that is highly oriented compared to conventional yarns and drawn fibers has high modulus, low shrinkage, and fatigue resistance, and is superior to conventional polyester cords. It is significantly improved compared to
It has excellent handling stability and ride comfort when driving at high speeds, and has fewer irregularities during tire molding (so-called f-n-1 bulges).
It is becoming popular and used. However, it still has insufficient modulus and shrinkage compared to older rayon fibers and vinylon fibers.

In addition, cords obtained from polyester fibers require a process of embedding them in rubber 11 and cooling them after vulcanization (so-called boss cure inflation).1 This cooling process requires a large capital investment, and in order to rationalize costs, this It is necessary to omit the process. For this purpose, it is necessary to have a low shrinkage comparable to cords obtained from rayon fibers or vinyl fibers, and the above improvement proposals are also insufficient.

C1 Problems to be Solved by the Invention The present invention provides a polyester cord suitable for industrial use, particularly a tire cord having a high modulus close to that of rayon cord.
The present invention provides a polyester fiber that can be used to produce a polyester cord that has low shrinkage and better fatigue resistance than rayon cord.

As a result of intensive studies in an attempt to provide such a polyester fiber, the present inventors have developed a specific fiber N structure in which a crystalline undrawn fiber with extremely high orientation compared to conventional fibers is used as a starting fiber, and this is subjected to multi-stage drawing heat treatment. They discovered that a polyester cord with low shrinkage and high modulus 1 lath close to that of rayon cord and better fatigue resistance than rayon cord could be obtained by using polyester fiber having
The present invention has been achieved.

d. Means for Solving the Problems The present invention relates to a polyester I fiber that can provide a polyester cord with high modulus and low shrinkage C fatigue resistance for industrial use. That is, it relates to a polyester fiber whose main structural unit is ethylene terephthalate, whose intrinsic viscosity is 0.90 or more, whose long period interval is 160 Å or more, and whose crystal melting point is 270° C. or more.

The present invention will be explained in detail below.

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. As such a polyester, il; redylene terephthalate is suitable, but it may contain other synergistic components in a proportion of less than 10%, preferably less than 57%. An example of such a co-synthetic component is isophthalic acid.

Nophthalene dicarboxylic acid, adipic acid, oxyben 15
acid, diethylene glycol, pyrene glycol,
Examples include trimellitic acid and pentaerythritol. Further, such polyester may contain additives such as stabilizers 1 and colorants, if necessary.

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 high-strength polyester cord cannot be obtained.

Particularly preferred is one with an intrinsic viscosity of 0.9 to 1.3.

In addition to the above-mentioned specific intrinsic viscosity, the polyester fiber of the present invention needs to have a specific fiber structure, that is, a long period interval of 160 Å or more, and a crystal melting point of 270° C. or more.

Here, the long period interval and crystal melting point are measured by method F below.

The long-period interval can be determined by Bragg from the meridional interference diffraction line obtained by using a small-angle X-ray scattering measurement device and using a conventionally known method, that is, using CIIK (xt/2 of wavelength 154 as a radiation source and irradiating at right angles to the axis of the Jll wheel). Calculated using the formula.

The crystal melting point was measured using 0SC-1τ1 manufactured by Pern Elmer Co., Ltd. at a heating rate of 20° C./min, and was defined as the “C crystal melting point” having an endothermic peak.

The polyester fiber of the present invention can be made into a polyester cord with high modulus and low shrinkage only by satisfying a long period interval of 160 Å or more and a crystal melting point of 270°C or more. It is difficult to achieve the object of the present invention even if the characteristic value of .

The polyester fiber of the present invention further has an amorphous orientation degree of 055
It is particularly preferable that the crystal volume is less than 4.5×10 5 3 or more.

The degree of amorphous orientation fa is determined by Robert J. Saminil (Rob
erL, J, Samuel)'s paper writing method (J,
POI-ymer 5science A2,10,78
1.1972).

'That is, Δn=X-rc-Δnc+(1-X) ra-
Δna Here, 80 is a parameter that indicates the degree of orientation of molecules in the filament, and was determined by the reflection method using bromonaphthalene as the immersion liquid and a Berek pensator. (Refer to Molecular Experimental Course/Physical Properties of Polymers ■1).

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

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

ΔnC1Δna is the intrinsic birefringence of crystals and amorphous, and is 0.220 for polyethylene terephthalate, respectively. 0.275
It is.

In addition, the hoochang body shoots were calculated as follows.

Crystal volume = a-axis crystal tin x b-axis crystal tin x
Long period interval x crystal formation Here, the crystal size is determined by the half value of the interference peak of the (010) (100) plane, and is calculated by q from the Scherrer equation.

Crystallinity 1 was determined by q using the Sakurada and parts method.

The degree of amorphous orientation of the polyester fiber of the present invention is not very high (although the molecular wI length expressed by the intrinsic viscosity is long, and the distribution of the degree of amorphous orientation is narrow and homogeneous, so the strength is 6SF/
de or higher, which is sufficient for industrial use.

The polynis del am of the present invention can be obtained, for example, by the following method. While reacting a polynis-al polymer containing ethylene terephthalate as a main component and having a limiting viscosity of 0.95 to 1.5 or a polymer having a limiting viscosity of 0.7 to 0.9 with a polymerization degree accelerator, It is melted and transported by a conventional method, and discharged from a spinneret into a yarn so that the fineness after drawing is 1 to 20 de,
Immediately after discharge, the yarn is cooled and solidified, either by rapid cooling, by keeping it at a temperature below the melting point or below the temperature at which crystallization begins, or by exposing it to a heated atmosphere at a temperature above the melting point for a certain period of time for delayed cooling, and then cooling and solidifying the yarn.

In this case, it is useful to avoid cooling and assimilation under the following conditions.

400≦(x-y)/Q≦1900 X is the distance from the spinneret surface to the cold IA air blowing surface and is 4
50 feet or less■ [If the length of the cooling air is 100 to 500 mQ, the amount of cooling air that is blown out is 2 to 68 m37 minutes After cooling and solidifying as described above, apply an oil agent and pull at a speed of 1500771,/min. take. The oil can be applied by any conventional method such as an oiling roller method or a spray method. In addition, as for the oil agent, it is possible to apply a general fiber oil agent according to the usual method, but in fields where adhesion with rubber is important for the application of 4111t, a surface treatment agent to provide easy adhesion may be applied. It is useful to grant.

By selecting the above-mentioned conditions as needed, crystalline undrawn fibers with an intrinsic viscosity of 0.90 or more and a cutting elongation of 150% or less, crystallinity λX and birefringence Δn can be obtained. , λX = 2.4x102xΔn+4, and an undrawn fiber having a birefringence of 006 or more can be obtained.

In the present invention, the undrawn fibers having the above characteristics taken at a speed of 15,007 FL/min or more can be drawn continuously after spinning or once wound (or drawn in the killing process). Good.If continuous drawing follows spinning,
This can be carried out in accordance with the method of the previously proposed patent [lnU37-88927g. 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 of No. 094. The latter stretching method is preferred in terms of reducing stretching strain during stretching and heat treatment strain. That is, untreated 1. 'I! ! l Shoulder t to Tg+
After preheating for at least 0.5 seconds at a temperature of 15 to +50°C (where TO is the glass transition temperature of the fiber), the total draw ratio is 7.
The first stage drawing is performed at a magnification 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, if high strength is required when corded, such as for tire reinforcement, the final tension heat treatment is performed at a temperature of - the melting temperature of iut -
Fixed length or 5.0 in the range of 50℃ to melting temperature -110℃
%, preferably a constant length or a tension of up to 2.5% and holding for 0.4 to 1.5 seconds is preferred.

When using the polyester fiber of the present invention as a rubber reinforcing cord, it is preferable to apply the following method, for example. That is, the drawn yarn is twisted with a twist coefficient = T-D (T is the number of twists per 1Oc11, D is the denier of the twisted yarn cord) of 900 to 2500 to form a twisted yarn, and the cord is glued with an adhesive. Following the treatment, heat treatment is performed at 235-250°C. At this time, the tension during heat treatment is 1.0-2.0 g/d.
It is preferable to carry out the heat treatment within the range a, under conditions in which stretching does not substantially occur.

The polyester cord obtained from the polyester aim of the present invention has a high modulus with an intermediate elongation Ei at a load of 2.0 g/da and a dry heat shrinkage rate S of Ei+3≦5.5, and extremely low shrinkage. 1, where the dry heat shrinkage rate is at a temperature of 115°C, and JI
SL, 1017-1963 (5, 12).

In addition, the polyester cord produced by the method of the present invention has a strength of 5.0 g/de or more and an elongation of 12% or more, and also has a lower heat generation temperature in rubber structures than conventional polyester cords for reinforcing rubber. The fatigue resistance has been significantly improved.

e. Examples The parts in Examples indicate the heavy parts. The characteristic values of the treated cord were measured by the following method.

(1) Load-stretching curve is JIS L 1017 1-6
3 (5, 4).

(21 Dry heat 115℃ shrinkage rate is JIS L 1017-1
963(5,12).

Lll 'F uup life is JIS L 1017-1
963. 1.3.2.1 Comply with eight laws. , l1IL
, the bending angle was 90''.

(4) RFLJ raw cord for strong heat resistance! Immerse it in the liquid,
Heat treatment was performed at 245° C. for 2 minutes under tension. Embed this processing cord in a vulcanization mold at 170℃ and pressure 50℃ for 9/d.
After accelerated vulcanization for 120 minutes, the sample was taken out and its tenacity was measured.

Practical Example 1 91 parts of dimethyl terephthalate, 69 parts of ethylene glycol, 0.034 part of calcium acetate monohydrate, and 0.025 part of ammonium oxide were placed in an autoclave.
IQ, l1, which removed methanol produced as a result of transesterification at 180 to 230°C while gently passing through the 9-fold
Add 0.05 part of 50% aqueous solution of 1r'o,+; heat 8 degrees to 280°C and gradually shift to reduced pressure,
It took about 1 hour to bring the pressure of the reaction system to 0.2 imHg,
The polymerization reaction was further performed for 1 hour and 50 minutes to form a unique groove 'il'i 0.
．． 80, terminal carboxyl group amount 28 equivalentffi/IOG
A small conglomerate of gram polymers was obtained. This polymer tin 110
After triblending 0 part with 2,2'-bis(2-oxazoline) from the can listed in Table 1 (indicated as CF), about 30
Melted and transported at 0°C, pore diameter 0.6 JlllI, number of pores 250
The discharged yarn was kept warm under the conditions listed in Table 1, and then cooled and solidified while blowing cooling air at 25°C over 300 m at a rate of 4.0 NII13/min. An oil agent was applied thereto, and the film was rolled up at the speed shown in Table 1. The properties of this undrawn fiber are shown in Table 1.

The obtained undrawn fibers are fed to a roll heated to 85°C, and the ratio (OR+) shown in Table 2 is applied between the undrawn fibers and the take-up roll.
After the first stage stretching, the film was stretched in the second stage at the magnification (DR2) shown in the table through a gas bath heated to 325°C. That v! 13
Using a heating roller at 0° C. and a gas reservoir at 330° C. as described in the table, tension heat treatment was carried out at I8ki (DR3) in Table 2+i. The performance of the stretched drawn yarn is also listed in Table 2.

- The obtained drawn yarn was subjected to 7 twists of 490 turns/rn, and then two of these were combined and the S twist of 490 turns/m was applied to LJ to obtain two 1000 deX raw cords. This raw cord was immersed in an adhesive (RFL) solution and subjected to tension heat treatment at 245°C 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 2.

Fruit/+I! Example 2 In Example 1, the addition can of 2.2'-bis(2-oxazoline) was set to 0.15 VTt%, and the pore size was 1.50 n.
The following undrawn fibers were prepared in the same manner as in Example 1 except that the temperature was 230°C, the blowing ratio of 6 groups was 120 mm, and the take-up speed was 2500 m/min. Obtained.

Intrinsic viscosity 0.92 Terminal carboxylic group concentration 8.0 Toyama/ton Birefringence 0.0707 Crystallinity
28.4% then the undrawn fibers were Dltl =
1.3, DR2=1.50, and DR3=1.05, the same procedure as in Example 1 was carried out to prepare 1q of the following drawn fiber sets.

Fineness 1005 de strength
7.4 g/de offshore degree
10.1% long period 165
Human melting point: 273° C. Crystal volume: 5.3×10” 3 Amorphous orientation: 0.50 The physical properties of the obtained dip cord were as follows.

Powerful 14.0 kg, shg
Loading elongation 3.5% cutting elongation
15.2% 175℃ dry yield 2
．． 3% Tube life 450 minutes Heat resistance strength maintenance rate 61% Procedure amendment May 1985

Claims (4)

[Claims] (1) A polyester fiber whose main structural unit is ethylene terephthalate, which has an intrinsic viscosity of 0.90 or more, has a long period interval of 160 Å or more, and has a crystal melting point of 270° C. or more. (2) The polyester fiber according to claim (1), which has a crystal volume of 4.5×10^5 Å^3 or more. (3) The polyester fiber according to claim (1) or (2), which has an amorphous orientation degree of less than 0.55. (4) The polyester fiber according to any one of claims (1) to (3), which has a cutting strength of 6.0 g/de or more.