JPS6038206A - Pneumatic tire - Google Patents

Abstract

PURPOSE:To sufficiently reinforce the captioned tire and improve fatigue resistance by reinforcing at least one of a belt and a carcass ply arranged inside a tread part by making use of a cord yielded by subjecting a polyester fiber having prescribed characteristics to original and final twisting. CONSTITUTION:In a pneumatic tire provided with a carcass ply layer 1 reinforced by a belt (braker layer) 4 arranged inside a tread 5, at least one of the belt 4 and the carcass ply layer 1 is reinforced by a specific polyester cord. For this cord, one obtained by subjecting a polyethylene fiber having the following characteristics to original and final twisting is used: intrinsic viscosity IV>=0.50, double refractive index in fiber cross section DELTAnA-DELTAnB<0, fiber double refractive index DELTAn>=180X10<-3>, fiber length period in small angle X-ray diffraction LP>=160 angstrome, specific gravity SG>=1.390, degree of shrinkage under a dry heat condition at 160 deg.C, SHD<=15%, and single yarn denier dpf<=35.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a pneumatic tire, and more particularly to a polyester fiber with high strength, improved dimensional stability, and improved fatigue resistance for use as a reinforcing cord for tire belts and carcass. This article relates to high-performance front pneumatic tires using.

Organic fibers such as rayon, polyamide, and polyester are well known as reinforcing materials for pneumatic tires.
Typical inorganic fibers are steel and glass fiber. Currently, polyamide is the mainstream organic fiber due to its high strength and durability. On the other hand, rayon has a high modulus of elasticity and good dimensional stability, so it holds a unique position as a reinforcing material for radial tires, especially in the passenger car field. Polyester, especially polyethylene terephthalate as a general-purpose material, can be considered to exist between polyamide and rayon in terms of characteristics, and its use as a reinforcing material for passenger car tires has increased in recent years, taking advantage of the fact that it does not produce flat spots. ing. However, the reality is that the production of rayon is decreasing year by year due to the instability of securing raw material cellulose resources and environmental problems such as bad odors and sewage generated during the manufacturing process, and the search for an alternative material is underway.

Although polyamide has excellent durability, it is difficult to replace rayon because it has a low initial elastic modulus, poor creep properties, and flat spots occur. On the other hand, polyester, particularly polyethylene terephthalate, has a better initial elastic modulus than polyamide, but cannot reach the level of rayon, and its durability is inferior to theramide. Furthermore, polyester has a higher shrinkage rate at high temperatures than rayon, which poses a problem in ensuring uniformity during the tire manufacturing process. However, this fiber has properties closest to those of rayon among general-purpose synthetic fibers and has the potential for improved performance, so many improvement techniques have been disclosed in recent years.

For example, (1) A method of increasing crystallinity using a low polymerization degree polymer (Japanese Patent Publication No. 49-21260. 51-45
690. Japanese Patent Publication No. 53-58028. 55-12202
4, 55-122015. Japanese Patent Publication No. 55-158324) and (2) a method of increasing the degree of crystallinity by strengthening heat treatment, and a method of combining this with increasing the thermal relaxation rate (Japanese Patent Publication No. 47-49771゜5-4B -16450, 52-8417. Japanese Patent Application Publication No. 1973-
There are improved techniques such as No. 41027 and No. 55-158324).

However, method 1) simultaneously causes a decrease in strength and deterioration of bending fatigue properties due to a lower degree of polymerization, making it impossible to obtain a polyester fiber with satisfactory overall performance, and method (I) reduces the shrinkage rate. Although this is possible, it also causes a decrease in strength and an increase in elongation and intermediate elongation, making it impossible to obtain fibers with excellent overall performance.

Polyester cord used as a reinforcing material for pneumatic tires is made into a woven fabric and then heat-treated to apply an adhesive until the tire is completed.

This adhesive application is carried out near the melting point of polyester,
Simultaneously undergo heat treatment in tension and relaxation states. The physical properties of the yarn are designed on the premise that it will pass through these processes,
It is necessary to optimize the physical properties of the cord, and a technology for manufacturing polyester tire cord from this perspective was recently disclosed in Japanese Patent Publication No. 7882/1982. The elongation at break is not specified, and the example is 24
~31%, rather than the values of previously known comparative examples of 17 to 23
%, tires using such cords have a large elongation at break, so there are concerns about creep performance and maneuverability.

Based on this background, the present inventors developed a d? As a result of diligent efforts to improve the strength and toughness of polyester fibers, we were able to obtain the desired polyester fibers.When this was made into cord and used in pneumatic tires, the overall performance was greatly improved. The tire was successfully developed and five inventions were completed.

That is, one aspect of the present invention is a pneumatic tire having a carcass reinforced with a belt disposed inside the tread portion, at least one of the belt and the carcass ply is reinforced with a polyester cord, and the polyester cord has the following characteristics. This is a pneumatic tire characterized by being made of polyester fibers having the following properties, which are first-twisted and first-twisted.

(a) Polyester in which 85 moles or more of the W return unit consists of ethylene terephthalate.

(b) IV≧0.50 (c) Δnmu ΔnB<0 (=) △n≧180xlO-1 − (e) LP≧16OA (hen SG≧ 1.390 ()) SHD≦15% (chi) dpf≦35 (However, in (a) to (h) above, IV is the intrinsic viscosity, △nm, ΔnB is the birefringence in the fiber cross section, △nm: fiber at the position of r/R = 0.9 birefringence △nn: r/R=O, birefringence of the fiber at the position R: radius of the fiber cross section r: distance from the central axis of the fiber cross section △n is the birefringence of the fiber, LP is the small angle Fiber long period in X-ray diffraction, SG is specific gravity, SHD is dry heat shrinkage rate at 160 ° C., dpf is single filament denier, and their definitions shall be in accordance with the following description. This is a pneumatic tire characterized by simultaneously satisfying the following characteristics (S) to (S) in addition to the characteristics (A) to (H).

(su) 0.65≦IV≦1.20 (nu) Δn≧195X10-1 (ru) △nl-△nB≦-1. OX 10-3 (O)
LP≧170A (Wa) DE≦10% (Force) DT≧1Of/d (Yo) OA≦8° (R) Td≧160℃ (Shi) Tp≧210℃ (However, the above (Wa) to (Shi) where DE is the cutting elongation, DT is the cutting strength, OA is the orientation angle of the (100) plane determined by wide-angle X-ray diffraction, and Tα is the temperature distribution of the mechanical loss tangent at 110 c/s. (The peak temperature of dispersion, Tp, represents the peak temperature of thermal stress during constant length heating, and the definition shall be in accordance with the description below.) The polyester fibers constituting the tire of the present invention have a higher temperature within the fiber cross section than ordinary thermoplastic polymer fibers. The birefringence distribution of the fiber is reversed, and the fiber has a unique birefringence distribution in which the inner layer has a higher birefringence than the outer layer. In addition, the fiber long period is 160λ or more (preferably 1r
oA or more) and longer than normal high-strength polyester fibers, has a cutting elongation of 10 inches or less, and has a fiber birefringence Δn of 180 x 10-3 or more (preferably 195 x 10
``6 or more), and by wide-angle X-ray diffraction (10
0) The orientation angle of the plane is 8″ or less, and it has a very high degree of crystal orientation, and the microstructure also tends to correspond to a super-tensioned or elongated structure.In addition, the specific gravity is 1.390. that's all,
The constant length heating thermal stress peak temperature is 210℃ or more, and the dry heat shrinkage rate SHD is 15% or less, indicating physical properties that have been sufficiently drawn and heat treated. ◎The most important practical performance is the fiber cutting strength of 10-DT. is 10 f/d or more, which is significantly improved compared to the strength of conventional high-strength polyester fibers, which is at most 9.5 t/d.

From the above, it can be said that the high-strength polyester fibers constituting the tire of the present invention have a completely new microstructure compared to conventional high-strength polyester fibers. Moreover, the molecular weight of the raw material itself does not need to be extremely high, and an intrinsic viscosity of 0.51 or more, preferably about 0.58 to 1.0, is sufficient. Of course, it is preferable that the molecular weight of the polymer be higher, but the most important feature of the polyester fiber of the present invention is that it has an improved microstructure.

A conventional method for producing high-strength polyester fibers is to use high-molecular-weight polyester (USP 28800).
57. French patent number 1281056.

1ti8 Publication No. 53-1367), a method using thick denier monofilament (Japanese Patent Application Laid-Open No. 51-15021), a method of spinning a high molecular weight polyester and then multistage drawing (USP 3651198), a method of delaying cooling and solidification during spinning. etc. have been proposed. However, with low denier filaments like the polyester fibers of the present invention, the distribution of birefringence within the fiber cross section is poor.

The idea of satisfying the requirements for a high-strength fiber by providing a unique birefringence distribution in which the inner layer has a higher birefringence than the outer layer has never been proposed.

The above-mentioned unique microstructure has an intrinsic viscosity of 0.51 or more,
1. When using a polyester in which at least 85 of the structural units are made of polyethylene terephthalate, the effect can be fully expressed, especially for high strength,
It has a remarkable effect on improving fatigue resistance. This is because in the case of polyester fibers whose main component is polyethylene terephthalate, in the conventional method, the fiber cross-sectional circular birefringence distribution of low-denier, high-strength filaments tends to be higher in the fiber outer layer than in the inner layer. This is thought to be because the spinnability and drawability of the fiber are inhibited, making it difficult to increase the number of tie molecular chains that substantially contribute to high strength.

Further, the present invention is unique in that the single fiber denier is 35 d or less. This is because when the single fiber denier becomes large, it becomes difficult to develop uniform stretching stress concentration in the inner layer portion of the yarn, and on the contrary, it becomes a factor that inhibits the stretchability.O Conventionally known high-strength polyester The degree of crystal orientation of the filament is the orientation angle (OA) of the (100) plane of 10
'', the degree of crystal orientation fc (formula [1] below) is less than 95q6, whereas in the case of the high-strength polyester fiber constituting the present invention, the orientation angle of the (100) plane is 8.
It has an extremely high degree of crystal orientation, which is less than 95% when expressed in terms of crystal orientation (fc).Also, the constant length heating thermal stress peak temperature, which is a measure of the drawing heat history, is 210%.
℃ or higher is also a major feature of the polyester fibers constituting the present invention. Especially when the peak temperature is less than 210℃
13-, it becomes difficult to express the unique distribution of birefringence within the fiber cross section, which is a feature of the present invention. When using high-strength fibers for industrial materials, especially tire cords, mechanical properties at high temperatures are one of the most important factors for practical performance.
Mechanical property evaluation at high temperatures is quite difficult, and even when tests are actually conducted, troubles such as polymer deterioration before measurement tend to occur, resulting in problems with measurement accuracy and reproducibility.

The present inventors evaluated the temperature dependence of dynamic viscoelasticity and mechanical temperature fractional characteristics as measures representative of the mechanical properties of fibers at high temperatures using a sandwich with a sinusoidal strain of 110 c/s. As a result, the temperature (
Normal high-strength polyester fibers have a Ta) of 2, which is at most less than 160°C, but the polyester fibers constituting the present invention exhibit a high temperature (Ta) of 160°C or higher.

Ta indicates the rigidity of the polymer in the amorphous portion, and the higher the Td, the smaller the degree of deterioration of the mechanical properties at high temperatures. Therefore, it can be said that the high-strength polyester fibers constituting the tire of the present invention have better mechanical properties at high temperatures than conventionally known high-strength polyester fibers.

Next, the birefringence distribution within the fiber cross section according to the present invention will be explained in more detail.

Δn mu Δnu<0 (c) Preferably Δn mu ΔnB≦-1,0X 10-8...
... (L) [However, △nm and △nB are as described above] is selected. In formulas (c) and (l), △n
M is representative of △n of the outer yarn layer, and ΔnB is representative of Δn of the inner yarn layer. It has a very unique microstructure of small size.

The distribution of birefringence within the fiber cross section of conventional polyester fibers tends to be higher in the outer layer than in the inner layer, and the cutting strength is only about 9.5 f/d at most.

Furthermore, the fact that the birefringence within the cross section of the fiber has a distribution in which it increases from the inner layer to the outer layer is considered to be a factor that inhibits stringiness and drawability in the spinning and drawing processes. .

Therefore, we conducted intensive research on spinning and drawing techniques and obtained the following findings. In other words, if the stretching stress can be concentrated in the center of the yarn by, for example, stretching the surface layer of the yarn while locally heating it during the stretching process, the stretching deformation pattern will be very mild, and the maximum stretching ratio can be reached. This can be improved compared to normal stretching methods. In addition, as has been pointed out with conventional drawn yarns, the phenomenon in which the drawing stress concentrates on the surface layer of the yarn, causing all defects and the fiber strength is significantly lower than the theoretical strength, is suppressed, and the final fiber The internal microstructure is the superstretched structure proposed by C1ark et al. [References: W, N, Taylor, Jr, l E, S
, C1ark+Polym, Eng, Sci, 1
B+ 518 (1978)), making it possible to obtain polyester fibers with superior tensile strength and breaking strength compared to conventional high-strength fibers for industrial materials. On the other hand, as seen in JP-A-51-15021, in the case of a thick denier polyester monofilament with a single filament denier of 1,000 d or more, a low distribution area of polymer chain segments near the surface of the filament can be used. However, as clearly stated in the published specification, even though this method is suitable for low denier filaments, Equivalent properties cannot be imparted to monofilaments. Furthermore, the cutting strength of the monofilament described in this publication is at most 8.4 f/
d, which is completely different from the low denier, high strength filament as intended by the present invention.

The present invention was completed as a result of further research based on the above findings.

Next, a method for producing polyester fibers having the above characteristics will be briefly explained, but the present invention is not limited to the method described below. In producing the polyester fiber of the present invention, the spinning and drawing process, especially the drawing process, is important. That is, 1. For example, when undrawn yarn with a birefringence of 0.002 to 0.060 obtained by melt-spinning polyester with IV≧0.58 is drawn continuously after spinning or once wound up and then stretched, 1 End drawing 17 - It is preferable to carry out the first stage drawing of 40% or more of the total stretching ratio between the drawn yarn first supply roller and the yarn maintained at 100° C. or lower, and if necessary, perform the undrawn yarn second supply roller. A high-temperature pressurized steam jetting nozzle is provided between the first stretching roller, the nozzle temperature is set to 200° C. or higher, high-temperature steam is spouted, and the stretching point is fixed near the high-temperature pressurized steam jetting nozzle. Furthermore, when performing the second-stage drawing, a slit heater (a heating device provided with slits as yarn running paths) with an ambient temperature of 170 to 420°C provided between the first drawing rods and the second drawing rods is used. A device that heats the yarn while moving it steadily through a slit in a non-contact manner; ambient temperature refers to the temperature inside the slit). , and subjected to a second drawn loaf. At that time, a temperature gradient is provided in the slit heater, and the atmospheric temperature at the yarn inlet is set to 170°C or higher and the exit atmospheric temperature is 420°C or lower.
It is preferable to allow the thread to pass through the thread so that the thread stays there for 8 seconds or more. In addition, after the two-stage stretching is completed, the film is continuously stretched without being wound up once.
Alternatively, it is possible to further improve the dimensional stability by subjecting the material to relaxation treatment at 230 to 165° C. below 0° after winding.

The polyester that is the raw material for the polyester cord intended in the present invention has an intrinsic viscosity of 0.50 or more, preferably 0.65, as measured at 30°C in a solvent of p-chlorophenol/tetrachloroethane = 3/1 (weight ratio). ~1.20, at least 85 moles, preferably at least 95 moles of the structural units consist of ethylene terephthalate, and other constituent units that can be mixed in small amounts include diethylene glycol and other carbon atoms having 1 to 10 carbon atoms. polyethylene glycol, hexahydro-p-xylylene glycol,
Isophthalic acid, dibenzoic acid * p-tert-phenyl-4,4'-dicarboxylic acid, aromatic dicarboxylic acids such as hexahydroterephthalic acid, aliphatic dicarboxylic acids such as adipic acid, hydroxy acids such as hydroxyacetic acid, etc. Such a polyester material is made into fibers by a conventional melt spinning method.

Such polyesters may be treated with matting agents, if necessary.
Pigments, light stabilizers, heat stabilizers, antioxidants, antistatic agents,
A dyeability improver, an adhesion improver, etc. can be blended, and all can be used except those that have a serious adverse effect on the characteristics of the present invention depending on how they are blended.

The tire of the present invention is manufactured using the cord made of the polyester fiber thus obtained.

That is, it is a pneumatic tire having a carcass reinforced with a belt placed inside the tread portion, and the polyester fiber obtained by the above method is used for at least one of the belt and the carcass ply. .

The pneumatic tire according to the present invention has excellent properties such as, firstly, it is highly strong and can be lightweight, secondly it has excellent bending fatigue resistance, and thirdly it has good uniformity.

By taking advantage of these nine excellent characteristics, it is possible to replace high-performance radial tires for passenger cars that previously used rayon cords, large tires that used polyamide cords, and large radial tires that use steel cords. This makes it possible to achieve higher performance and lighter weight.

The present invention will be explained below with reference to Examples. In addition, the definition and measurement method of the characteristics of the yarn described in the explanation and examples are shown below.

<Measurement method of intrinsic viscosity> Measurement is performed in a mixed solvent consisting of 75% by weight of p-chlorophenol and 25% by weight of tetofuchloroethane.

The polymer is dissolved in a solvent at room temperature and the viscosity measurements are carried out in an Ostoldoffenske capillary viscosity needle at 30°C.

Intrinsic viscosity is the limit value at which the natural logarithm of the ratio of solution viscosity to solvent viscosity divided by the concentration of the polymer solution in grams of polymer per 100 g of solution approaches zero concentration.

21- <Method for measuring birefringence (△n)> Using a Nikon polarizing microscope POH type Uin Co., Ltd. Berek condensator, turn on the light source and activate the Fi Nuvector light source activation device (Toshiba 5LS-3-B type). (Na light source). 5
~6I! A sample cut at an angle of 45° to the I-length fiber axis is placed on a glass slide with the cut side facing up.

Place the sample slide glass on the rotating stage, adjust the rotating stage so that the sample is at a 45° angle to the polarizer, insert the analyzer, set the dark field, and set the compensator to 30°. count the number of stripes (n pieces). Turn the compensator clockwise K to set the scale a on the compensator to the point where the sample first becomes darkest, and turn the compensator 4 K to the left to set the scale A on the compensator to the point at which the sample first becomes darkest. After measurement (read up to 1/10 scale in both cases), return the % compensator to 30, remove the analyzer, measure the diameter d of the sample, and calculate the birefringence (△n) based on the following formula (measurement (average value of several 20).

22- Δn=7'/drniteraption,=nλ6-) lλo=589
．． 3mμ #: C/100 in the manual of Fuitsu's compensator
00 and I = (difference in compensator readings in (a-b)) Measuring method of 60 distribution in fiber cross section
nl, 0 and n7.0) and outer layer refractive index (nl, 0.
The values of 9 and nl, (j,9) reveal the unique molecular orientation of the fibers of the invention and can be associated with the superior strength of the fibers of the invention.

The distribution of the average refractive index observed from the side surface of the fiber can be measured by the interference fringe method obtained using a transmission quantitative interference microscope (for example, Interfaco interference microscope manufactured by Carl Zeiss Jena, East Germany). This method can be applied to fibers with a circular cross section. The refractive index of the fiber is
Refractive index for polarized light vibrating parallel to the fiber axis (
nl) and the refraction *(nl) for polarized light oscillating perpendicular to the fiber axis. All measurements described here are carried out using a xenon lamp as a light source, under polarized light, with refractive indices Cn7 and nl) obtained using an interference filter and a green light beam of wavelength 544 mμ.

The following nl, 0 and nl are determined from the measurement of n/ and nl,
Although 0.9 will be explained in detail, nl (nl, 0 and nl, 0.9) can also be measured in the same way. The fibers to be tested use optically flat glass slides and coverslips, with an inert encapsulation for the fibers with a refractive index (nu) that provides a shift of the interference fringes in the range of 0.2 to 1 wavelength. immerse in the agent. The refractive index (nu) of the mounting medium is a value measured at 20° C. using an Atsube refracting needle using green light (wavelength λ=544 mμ) as a light source. This mounting medium can be adjusted to have a refractive index of 1.48 to 1.65 from a mixed solution of liquid paraffin and α-bromnaphthalene, for example. A single fiber is immersed in this mounting medium. Take a photograph of this interference fringe pattern and magnify it by 100 to 2000 times.
Analyze at double magnification. As shown in Figure 1, the refractive index of the fiber encapsulant is nE, the average refractive index between 57 and 5 # of the fiber is n 7 @ the thickness between S' and S' is t, and the wavelength of the light beam used is λ , where Dn' is the spacing between the staggered patterns of the pack ground (corresponding to 1λ), and dn is the deviation of the interference fringes caused by the fibers, the optical path difference is expressed as follows. If the refractive index of the sample is n8, the refractive index of the filled liquid is nl/ and n2.

Evaluate the finer interference fringe pattern shown in Figure 1 using two types of n6<nl n@)nl ◎ 25- Therefore, based on formula [2], at each position from the center of the fiber to the outer periphery, From the optical path difference of , the fine average refractive index (n
The distribution of l) can be calculated.

The thickness t can be calculated by assuming that the obtained fiber has a circular cross section. However, due to variations in manufacturing conditions or accidents after manufacturing, there may be cases where the cross section is not circular. In order to eliminate this inconvenience, it is appropriate to use a portion to be measured where the displacement of the interference fringes is symmetrical with the fiber axis as the axis of symmetry. Measurements are made between 0 and 0.9 H, where R is the medium diameter of the fiber.
By performing this at intervals of H, the average refractive index at each position can be calculated. Since the distribution of nl can be determined in the same manner, the birefringence distribution can be determined using the following equation (3). Δn(r/R) is obtained by averaging measurements made on at least 3 filaments, preferably 5 to 10 filaments.

<Method for measuring strength and elongation properties of fibers> Test 26 using Ten V Ron manufactured by Toyo Bold Twin Co., Ltd. (gauge length) 100 m, elongation speed = 100 cm/min, recording speed 5QQiw/min, initial load 1 The S-8 curve of single fiber was measured under the condition of /30y/d, and the cutting strength (f/d),
Cutting elongation (%) and initial elastic modulus Cf/d) were calculated.

The initial elastic modulus was calculated from the maximum slope near the origin of the S-5 curve. Regarding the calculation of each characteristic value, the measurements for at least 5 filaments IP, preferably 10 to 20 filaments I-, are averaged.

<Measurement method of fiber long period LP by small-angle X-ray diffraction> Small-angle X
The line pattern irregularity pattern is measured using, for example, an X-ray generator manufactured by Rigaku Corporation (RU-3H type). For measurements, the tube voltage was 45 KV and the tube current was 70 mA.

It is made monochromatic with a copper anticathode and a nickel filter to produce 9CuKα (
λx=1.5418A) is used. Attach the fiber sample to the sample holder so that the single threads are parallel to each other. It is appropriate that the thickness of the sample be about 0.5 to 1.0 .mu.m. X-rays are incident perpendicularly to the fiber axes of the fibers arranged in parallel to produce P S P C (made by Rigaku Denki).
Position 5ens mouth ive Propor-
t 1ona I , Counter ) system. Book V7. The outline of Tum is 5. For example, [P
olmer JournalLvol.

13.501 (1981)).

The measurement conditions were as follows: 0.3aφXO, 2amφ medium pinhole collimation, distance between sample and probe = 400 degrees, number of MCA (multichannel analyzer) measurement channels: 256, and measurement time 2600 seconds. The data was processed by subtracting the air scattering intensity from the measured scattering intensity, performing a moving average process, and reading the position of the maximum intensity.

According to the following formula [4] from the long-period small-angle scattering angle 2α.

Calculate the fiber length period [See Figures 2 (A) and (B) In the two figures, 1' is the sample, 2'' is the PSPC Proso, 3' is the position analyzer, 4-digit MCA, and 5 is the display section. ].

λX LP=...Song...[4] 2sinα λx=1.541E3A The moving average processing is calculated according to a linear equation.

Tomodashi, in the above formula, I(S)N and I(S)1 digit, the measured scattering intensity (intensity after subtracting the air scattering intensity) of channel numbers N and 1, respectively, and the adopted score of the moving average (
here -7).

N-K>Or N+≦256 <Method for measuring orientation angle (OA)> The orientation angle (OA) of fibers can be measured using 1, for example, a Rigaku x1 generator (RU-3H) or a fiber measuring device (FS). -3
), a goniometer (SG-7), and a scintillation counter.

For the measurement, CuKα (wavelength λ=1.541 sA>) made monochromatic with a nickel filter is used.

To measure the orientation angle, 20 of the (100) plane reflection is used.

The 20 reflections used are determined from the equatorial diffraction intensity curve.

The X-ray generator is operated at 45 KV and 70 mA', and the fiber sample is attached to the fiber measuring device so that the single yarns are parallel to each other. The thickness of the sample is 0.5
It is appropriate to set K to the fi position.

Set the goniometer to the 2θ value determined by preliminary experiments. X perpendicular to the fiber axis of the fibers arranged in parallel
Inject the beam (beam vertical transmission method). The azimuthal direction is scanned from -30' to +30°, and the diffraction intensity is recorded on recording paper using a scintillation counter. Further -180° and +
Record the 180° diffraction intensity.

At this time, the scanning speed is 4°/i and the chart speed is 1. OLM/m + time constant 2 seconds or 5 seconds, collimator 1111φ, and receiving angle of 1° in both length and width of the slit.

To freeze the orientation angle from the obtained diffraction intensity curve, +18
Take the average value of the diffraction intensity obtained at 0° and draw a horizontal line. Drop a perpendicular line from the top of the peak to the base line, and measure the midpoint of its height. Draw a horizontal line through the midpoint. Measure the distance between the intersection of this horizontal line and the diffraction intensity curve and convert this value into an angle (°
) is the orientation angle (OA) 〇30-〈Mechanical temperature fraction〉 Rheovibron manufactured by Toyo Side Type Co., Ltd. is used, and the initial yarn length is 4.
c1n, heating rate 2°C/min, sine frequency 110 during measurement
Measured under Hz condition, loss tangent tanδ=E'/
Find the temperature (Tα) at which E' is maximum.

However, in the above formula, Hz is the storage modulus (dyne/d
), E is the loss modulus (dyne/aA).

[For details - Memoirs of tbe Facul
Ty of Engi-neering Kyush
u University) r+ vol, 23+ 4
1 (1963)] The complex modulus of elasticity E is calculated by the following formula.

However, A: Coefficient due to the amplitude factor (Ampl +Eactor) during tanδ measurement (
(See Table 1) D = Dynamic Force Dial value L:
Sample length (crn) S: Sample cross-sectional area (CIA) 1st surface loss modulus EI/ll E”= l E I sin δ
・・・・・・・・・It is divinely summoned by [6].

Single thread denier Measured according to JIS-L1073 (1977).

<Dry heat shrinkage rate> Measured according to JIS-L1073 (1977) at 160°C. <Specific gravity> A density gradient tube made of n-hebutane and tetrawarmed carbon was prepared, and the temperature was adjusted to 30°C ± 0.1°C. Place the sufficiently degassed sample into the density gradient tube, and after leaving it for 5 hours, read the sample position in the density gradient tube on the scale of the density gradient tube. Converted to specific gravity value from specific gravity Calipre Vagbufu and measured with n-4. As a general rule, read specific gravity values to four decimal places.

<Constant length heating thermal stress peak temperature> Trial length 45 sub, heating rate 20℃/min, initial load 0.05f/
Measure the thermal contraction stress from room temperature to the melting temperature under the conditions d, and find the temperature at which the thermal stress is maximum.

[For details, see Textile Re5earch Jour
nal, vol. 47+732 (1977). ] indicates "parts by weight" □ and "parts by weight" unless otherwise specified.

Example 1 Using polyethylene terephthalate having an intrinsic viscosity shown in Table 2 as a raw material, spinning was carried out under the conditions shown in the same table to obtain an undrawn yarn having a birefringence shown in the same table. During spinning, an appropriate amount of spinning oil was applied to the surface of the 33-fiber yarn before taking off the undrawn yarn.

The obtained undrawn yarn was drawn under the conditions shown in Table 3.

A drawn yarn having the quality shown in Table 4 was obtained. Comparative example 2 in Table 4
Also, the yarn quality of high-strength grade polyester fiber for tire cords is also listed.

Table 2 34 - Table 3 Table 4 A 1000 denier multifilament yarn was obtained, and the raw cord obtained by twisting it under the conditions shown in Table 5 was dipped in a resorcinol-formaldehyde-latex treatment solution according to a conventional method. Regarding cords obtained by similarly dipping conventional polyester cords,
We attempted to compare the general cord (dip cord) characteristics and tube fatigue properties.

In addition, among the general cord characteristics in Table 4, the strength and elongation characteristics are 2.
After leaving the sample in a room at 0° C. and 65% relative humidity for one day, it was measured using a constant speed extension type tensile tester.

The dry heat shrinkage rate was measured after leaving the sample in air at 150°C for 30 minutes, and the creep rate was measured after leaving it for 60 minutes under a load of 1 r/d in an atmosphere of 20°C and 65% relative humidity. The elongation rate was measured.

In addition, the tube fatigue test was performed using a tube fatigue tester manufactured by Toshi Engineering Co., Ltd., with a tube bending angle of 60',
Rotation speed 850 revolutions/minute, reverse every hour, air pressure 30k
The tube was operated under r/aA conditions, and the time until rupture was defined as the tube life.

The tube surface temperature was measured by measuring the temperature at the part of the tube with the maximum curvature using a radiation temperature needle when the equilibrium temperature was reached.

As is clear from Table 5, the polyester dipped cord according to the present invention has significantly improved strength and elongation characteristics as compared to the conventional polyester dipped cord, and also has excellent dimensional stability.

On the other hand, in the tube fatigue test, the cord of the present invention had a lower heat generation temperature and a longer life.

From the above, it can be clearly understood that the cord of the present invention has higher strength and superior fatigue resistance than conventional cords.

Next, using the polyester dipped cord according to the present invention shown in Table 5, a tire as shown in Fig. gJ3 was manufactured.

In other words, the tire is made of ply made of cords woven into a blind shape.
Bead wires 2 are placed on both left and right sides of a carcass ply layer 1 consisting of one or more plies, and the carcass ply layer 1 is curved into an arcuate shape. carcass ply layer 1
A breaker layer 4 is provided on the crown portion 3 for reinforcement, and the periphery of these constituent layers is further covered with a rubber layer (tread) 5 to obtain the tire of the present invention. The material of the rubber layer is not particularly limited; for example, natural rubber, butyl rubber, butadiene rubber, nitrile butadiene rubber, styrene butadiene rubber, imprene rubber, and blend rubbers thereof in arbitrary proportions can be used.

As clarified by the comparative study of the above Examples and Comparative Examples, the polyester cord used in the tire of the present invention has excellent strength as a yarn itself, and as a result, the tire of the present invention has high strength.

It exhibits excellent performance such as fatigue resistance, and exhibits performance that cannot be obtained with tires using conventional polyester cord.

[Brief explanation of drawings]

FIG. 1 (A) is a schematic diagram showing the interference fringes seen when the fiber of the present invention is observed from the side with an interference microscope, and FIG. 1 (B)
2(A) is a schematic diagram showing the arrangement of the sample and film surface in small-angle X-ray diffraction measurement;
B) is a schematic diagram showing a small-angle X-ray diffraction pattern of the fiber of the present invention, and FIG. 3 is a half-sectional view of a main part of the tire of the present invention. 1...Carcass ply layer 2...
... Bead wire 3 ...... Crown portion 4 ...... Player layer 5 ...... Tread patent applicant Toyobo Co., Ltd. 41- Kazuaki 1 Figure (A) Figure 3 (B) 38-11

Claims (1)

[Claims] 1. A pneumatic tire having a carcass reinforced with a belt placed inside the tread. A pneumatic tire 0 characterized in that at least one of the belt and the carcass ply is reinforced with a polyester cord, and the polyester cord is made of polyester fibers having the following characteristics that are first twisted and second twisted. (a) A polyester in which 85 moles or more of the repeating units consist of ethylene terephtha (1/-). (b) IV≧0.50 (c) Δnmu Δn B < 0 (d) Δn≧180X10-1 (e) LP≧16OA (f) SG≧1.390 ()) SHD≦151 (chi) dpf≦ 35 (However, in (a) to (h) above, IV is the national viscosity, ΔnAb80B is the birefringence in the cross section of the fiber, Δnmu is the birefringence of the fiber at the position of +r/R=0.9 ΔnB sr/R=O,, Birefringence R of the fiber at the position of 0: Radius of the fiber cross section rl Distance from the central axis of the fiber cross section Δn is the birefringence of the fiber % LP is the fiber at the small angle X-ray diffraction Long period, SG stands for specific gravity, SHD stands for dry heat shrinkage rate at 160°C, and dpf stands for monotonous, thread deformation, and neil, and their definitions shall be in accordance with the description in the main text.) 2. Claim 1 In the pneumatic tire described above, the polyester fiber further satisfies the following characteristics at the same time. (su) 0.65≦IV≦1.20 (nu) △n≧195X10-8 (ru) △nl-△nB≦-1. OX 10-8 (O)
LP≧170A (Wa) DE≦10% (Force) DT≧10f/d (Yo) OA≦8゜ (R) Tα≧160℃ (Shi) Tp≧210℃ (However, the above (Wa) to (Shi) where DE is the cutting elongation, DT is the cutting strength, OA is the orientation angle of the (100) plane determined by wide-angle X-ray diffraction, and Tα is the principal dispersion appearing in the temperature fraction of the mechanical loss tangent at 110 c/s K. The peak temperature, Tp, represents the constant length heating thermal stress peak temperature, and the definition shall follow the description in the text.)