JPS5812804A - Pneumatic tire - Google Patents

Abstract

PURPOSE:To improve the total performance of a tire by reinforcing a belt, a carcass etc. by the polyester cord which is made of polyethylene terephthalate fiber and possesses prescribed characteristics. CONSTITUTION:At least either one of a reinforced belt and a carcass ply is reinforced by polyester cord. Said polyester cord fulfils the following characteristics at a same time: (a) DT/D>=4.5(g/d), (b) 5<=Mt<=25(g/d), (c) 0.05<=Mt/Mi<=0.50,(d) 8.0<=DE<=25(%), (e) 1.0<=DELTAS<=7.0(%)[In (a)-(e), DT/D is strength, Mt is terminal modulus, Mi is initial modulus, DE is elongation at rupture, and DELTAS is dry thermal contraction rate at 177 deg.C]. Thus, the total performance such as the fatigue proofness, chemical deterioration proofness, dimension stability etc. can be improved.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a pneumatic tire, and more particularly to a pneumatic tire that has a high elastic modulus, improved dimensional stability, fatigue resistance and chemical resistance, and is used as a reinforcing cord for a tire belt or a carcass. This article relates to high-performance pneumatic tires using polyester cords with improved deterioration resistance.

Rayon, polyamide, and polyester are well known as m* fibers as reinforcing materials for pneumatic tires.
Typical inorganic fibers are steel and glass fiber. Polyamide is the most popular 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 been increasing in recent years due to its lack of flat spots. are doing. By the way, rayon suffers from the instability of securing raw material cellulose resources.1. The reality is that the production volume is decreasing year by year due to environmental problems such as bad odors and sewage generated during the manufacturing process, and the search for alternative materials is underway.

Although polyamide has excellent durability, it has a low initial elastic modulus, still has poor creep properties, and flat spots occur, making it difficult to replace rayon. On the other hand, polyester, especially polyethylene terephthalate, has a better initial elastic modulus than polyamide, but cannot reach the level of rayon, and its durability is inferior to polyamide. Furthermore, polyester has a higher shrinkage rate at high temperatures than rayon, which poses a problem in ensuring uniformity during the tire manufacturing process. real power;
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 regarding this fiber.

For example, (1) a method of increasing crystallinity using a low polymerization degree polymer (Japanese Patent Publication No. 49-212'60゜Doubt 51-4
5690, JP 53-58028, JP 55-1220
24, 55-t 22015, 55-158j24
(11) A method of combining increasing the degree of crystallinity by increasing the heat treatment, and increasing the thermal relaxation rate (% Publication No. 47-49771, 4th-1st of the same year)
6450, 52-8417, JP-A-48-41027
, No. 55-158324).

However, method (+) 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. 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 the polyester and is simultaneously subjected to heat treatment under tension and relaxation. It is necessary to design the physical properties of the yarn and optimize the physical properties of the cord on the premise that it will pass through such a process. Although it was recently disclosed in the publication, the elongation at break of the cord before vulcanization is not specified in the publication, and the examples are 24 to 31%.
In fact, it is even larger than the values of conventional comparative examples, which are 17-26%. Tires using such cords have a high elongation at break, so there are concerns about creep properties and handling conditions.

With this background in mind, the present inventors have developed a technology that maintains a high initial modulus of the reinforcing cord in a completed tire, provides excellent vehicle handling performance, and provides excellent tire durability. As a result of our intensive efforts to develop a polyester cord that can improve uniformity and creep performance, we were able to obtain the desired polyester cord, and at the same time, when used in tires, we were able to develop tires with significantly improved overall performance. He was successful and completed his invention.

That is, the present invention provides a pneumatic tire having a carcass reinforced with a belt placed inside the tread portion, in which at least one of the belt and the carcass ply is reinforced with polyester cord, and the polyester cord is substantially This pneumatic tire is made of polyethylene terephthalate fiber, and the polyester seeds in the tire satisfy the following characteristics at the same time.

DT/D≧4.5 (g/d) (b)
5 ≦ Mt ≦ 25 (g/d) (c) 0.
05≦M t / M i≦0.50) 8.0≦D
E≦25(%) ゛(E) 1.0≦△S≦7.
0 (e) [However, in (a)-S-(e) above, T/D is the strength, Mt is the terminal modulus, Mi is the initial modulus, D'E is the elongation at break, and △S is at 177°C.・Represents the dry heat contraction rate at ] More preferably, it is a pneumatic tire characterized by simultaneously satisfying the following characteristics in addition to the characteristics (a) to (e) above.

(f) 2.5≦MDE≦8.0 (X) (g) 4.
0≦MDE16S≦16 (%) [However, in the above H, MDE represents the elongation at a stress of 2.25 g/d, and the same shall apply hereinafter), and the definition shall be in accordance with the following description. ] The polyester tire cord used as a reinforcing material in the tire of the present invention consists essentially of polyethylene terephthalate fibers, and the DT/D of the cord is 4.5 g.
/d or more, preferably 5.0 g·74 or more, and 4.
If it is less than 5 g/d, it is not useful as a reinforcing material for the tire. hlt is 25-5 g/d%, particularly preferably Id2
It is 0 to 5 g/d. N1t of cord in conventional tire
shows a value exceeding 25 g/d, and the effect of improving fatigue properties as in the present invention cannot be obtained. Furthermore, if Mt is less than 5 g/d, it is difficult to maintain DT/D within the above range. The relationship between Mt and Mi is M't 7M i 75(0
, 50-0,05F) range, particularly preferred tL< is 0.45 to
It is in the range of 0.05. If M t /Mi exceeds 0.50, the bending fatigue properties of the tire will be significantly reduced and the tire performance of the present invention cannot be obtained. Also M
When t/M i is less than 0.05, it becomes difficult to satisfy the characteristics of DT/D. Until now, the coat inside the tire "Q, M t /Mi has exceeded 0.50,
At the same time as Mt decreases, Mi also decreases, and Mi
It has been impossible to reduce Mt while keeping it high.

The present invention is characterized in that Mt shows a small value and Mi shows a large value at the same time, and as a result, Mt/Mi shows a small value. 5 DE is in the range of 25 to 8%, particularly preferably in the range of 20 to 8%. DE is 2
If it exceeds 5%, the creep performance of the tire may deteriorate, or -
Maneuverability deteriorates. Moreover, if DE is less than 8%, the shrinkage rate will increase, Mt will increase, and the tire performance of the present invention cannot be obtained. ΔS is ZO~1.0%, particularly preferably 1
．． It is 0 to 6.5%. When ΔS exceeds 70%, the uniformity of the tire decreases.

When ΔS is less than 1.0%, Mi decreases and the steering stability and ride comfort of the vehicle deteriorate. MDE is 8.0 to 2.5%, particularly preferably ZO to 3.0%, and MDE and ΔS
When the sum of P is 15.0 to 4.0, particularly (preferably 12.a to 5.0%).

In general, the degree of polymerization of polyester is set at one level, and the MDE and ΔS characteristics of polyester cords manufactured from polyester fibers manufactured by the same spinning method are changed by changing the temperature and stretching ratio during adhesive treatment. can be changed. If a high modulus of elasticity is desired, the draw ratio is increased and MDE is set to be small; on the other hand, if uniformity is to be improved, the draw ratio is decreased to reduce ΔS. However, in this case, the sum of MDE and ΔS is almost equal to the value, and if either MDE or ΔS is tried to match the desired characteristics, the other inevitably exhibits disadvantageous characteristics. Therefore, in order to improve any of the characteristics, it is desirable to reduce this sum, P. In the previous tires, the P value was 13
In order to achieve a value of 96 or less, the main method was to lower the degree of polymerization, improve crystallinity, and reduce ΔS, but this would conversely reduce the flexural fatigue resistance, making it impossible to obtain a practical tire. That was impossible. Another method is to reduce the number of twists in the cord, but this also significantly reduces the bending fatigue resistance. In the present invention, by using polyester fibers to be described later, ΔS can be significantly reduced, and the value of P can be reduced to 16% or less. This method has made it possible to obtain tires with high elastic modulus and good dimensional stability. .

The difference between the tire of the present invention and the conventional tie i is that the polyester cord taken out from the tire is DT/DSMt,
Ml/Mi, 'DB, △S1 More preferably, MDE and MDE+△S are satisfied at the same time, especially M
It is characterized in that t and M t /M i exhibit small values.

It is known that reducing Mt is effective in improving flexural fatigue resistance, but in conventional tires, reducing Mt inevitably resulted in a decrease in Mi and an increase in MDB+DE. . On the other hand, it was also impossible to reduce simultaneous cough ΔS to 70% or less with MDE and DE within the range of the present invention.

The tire cord used in manufacturing the tire of the present invention can be manufactured using the previously proposed polyester fiber having the following properties.

That is, (a) Initial tensile resistance ≧1100 (/d) 1 port) Terminal modulus ≦15 (g'/dJ (c) Δ5is
oc/IV≦ao(%)) Birefringence nD=170x10
""~190x10-" (e) Crystal orientation function fc≧α
93 (f) Amorphous molecular orientation function F≦α92 (g) Crystal size D≧47 (X) (e) Long period Lp≦145' (X) (However, △S in (c) above is 15
The dry heat shrinkage rate at 0°C and Iv represent the intrinsic viscosity. In addition, the definition of characteristics shall comply with the following description. ) Furthermore, more preferred is a polyester fiber that simultaneously satisfies the following chemical properties in addition to the above properties.

(IJ) IV ≧ 170) Carboxyl terminal group concentration HCOOH≦25 (eq/
10'g) (However, the definition of C-00H shall follow the description below.) Polyester fibers satisfying the above characteristics can be obtained by the following manufacturing method.

(a) Melt spinning with a polymer in which 90 mol% or more of the total number of repeating units in the molecular chain is polyethylene terephthalate units.

(b) The take-up speed of the spun yarn after solidification of the melt-spun spun yarn is 2 & 1 min or more, particularly preferably 2.7 min.
)[The material must be taken up with a take-up roller at a speed of at least m/min.

(c) The atmosphere directly below the spinneret is surrounded by a heating cylinder or a heat-insulating cylinder, and the temperature of the atmosphere is maintained so that the birefringence n8 of the yarn passing through the take-up roller satisfies the following formula.

t3x10'-"x(7,2V"-20V+30)
≧△n5≧α7×10・−3x (7,2V” −20
V+31)) (However, V in the above formula represents the take-up speed (&I/min) of the spun yarn.) Stretch the taken-off spun yarn by 1.4 to 3.5 times. .

The multifilament made of polyester fiber obtained in this way is given a first twist and a second twist to make an untreated cord, and the number of twists at this time is the twist coefficient K shown by the following formula.
is in the range of 1000 to 3300, more preferably 1300
It is preferable to set it in the range of ~3000.

K=N5 [However, K is the twist coefficient, N is the number of twists per 10 crn of the cord, and D is the fineness (denier) of the twisted cord. ] After poisoning this untreated cord with adhesive and drying it,
00°C to melting point of polyester, particularly preferably 260 to
Heat treatment is performed under tension at 255°C for 30 to 500 seconds. By appropriately setting the stretching ratio during this heat treatment, the intermediate elongation of the treated cord (hereinafter referred to as treated cord) can be set to a desired value. In order to obtain the physical properties of the cord taken out from the tire of the present invention, it is advantageous to make the heat treatment temperature as high as possible and the drawing ratio during heat treatment as small as possible as the heat treatment conditions when producing the treated cord. be. For this purpose, it is advantageous to set the intermediate elongation of the untreated cord and the intermediate elongation of the polyester fiber as small as possible.

For example, in the case of =2100 to 2600, the following is true.

Elongation of raw yarn at 4.5 g/d load = 3.5 to 7.
0. , X untreated cord elongation at 2.25g/d load 4
．． 5-aO% Adhesive processing temperature = 255-255°C Final stretch ratio during adhesive processing = α97-1.07 (However,
The final draw ratio is the sum of the draw ratios in each of the heat treatment zone and normalizing zone. ) When the value of K is smaller than this, the final stretching ratio is made smaller; conversely, when the value of K is larger than this, the final drawing ratio is made larger.

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

That is, it has a carcass reinforced with a belt placed inside the treft part.

The present invention is a pneumatic tire in which polyethylene terephthalate fiber obtained by the method described above is used in at least one of the belt and the carcass ply.

The pneumatic tire according to the present invention has firstly a high elastic modulus and excellent handling stability, secondly has good uniformity, sixthly has excellent bending fatigue resistance, and fourthly has creep resistance. It has excellent characteristics such as small Taking advantage of these excellent properties, we have created high-performance radial tires for passenger cars that previously used rayon cord, large tires that used polynamide cord, and large radial tires that used steel cord.

It becomes possible to replace it with , making it possible to achieve higher performance and lighter weight.

The cine invention will be explained below with reference to Examples. The definition and measurement method of the characteristics of the yarn and cord described in the above explanation and Examples are shown below.

1. Tensile test The test was conducted according to JIS-Ll 017 method. Intermediate elongation (
MDE) was the elongation at stress of 4.5 g'/d for raw yarn, and the elongation at stress of 2.25 g/d for the cord.

In addition, the cutting strength and initial elastic modulus obtained from the load-elongation curve (
Initial tensile resistance), terminal modulus, etc. are not corrected for the decrease in denier due to elongation of the sample during measurement. The load-elongation curve was obtained by measuring under the following conditions. Take the sample in the form of a skein, leave it in an atmosphere adjusted to 25℃, 65% R, H for 24 hours, and then 1 tensileon''UT
The measurement was carried out using an M-LL type tensile testing machine (manufactured by Toyo Baldwin Co., Ltd.) at a sample length of 25 m and a tensile speed of 30 m/min. From the load-elongation curve obtained here, the initial modulus (initial tensile resistance, M i ) was measured according to the definition of JIS-Ll 017.Similarly, the terminal modulus was determined by dividing the increase in stress on the curve obtained by subtracting 2.4% from the elongation at break by 2.4X10'''3. Ta.

This is shown surrounded by a chain line Mt on the curves X and Y of the drawing (Mi of the conventional polyethylene terephthalate fiber is shown by the curve X, and that according to the present invention is shown by the curve Y).

2. Dry heat shrinkage rate △S Take the sample into a skein and place it in a temperature-controlled room at 20°C and 65% RH for 24 hours.
After leaving it for more than an hour, the length of the sample, measured by applying a load equivalent to [11g/d, t3o] was placed in an oven at 15-0℃ for raw yarn and 177℃ for cord in a non-tensioned state for 60 minutes. After leaving it for a few minutes, it was taken out from the open air and left in the temperature-controlled room for 4 hours, and then the load was applied again and the measured length 11 was calculated using the following formula.

△S= (Jo −Js) /−eo X 100
(FA) 3. Birefringence The birefringence was determined by the usual Benz compensator method using a POH type polarizing microscope made by Nikon ■ and using the D line as a light source. The birefringence of the undrawn yarn was designated as Δn8, and that of the drawn yarn was designated as ΔnD.

4. Amorphous molecular orientation parameter p
It was immersed in a wt% aqueous solution at 55° C. for 3 hours, thoroughly washed, and then air-dried to prepare a measurement sample. JASCO Corporation fiF
Using an OM-1 polarization photometer, the relative intensity of polarized fluorescence was measured at an excitation wavelength of 36.5 nm and a fluorescence wavelength of 420 nm, and was determined by the following equation.

F=1-B/A However, A: Relative intensity of polarized fluorescence in the fiber axis direction B: Relative intensity in the direction perpendicular to the fiber axis 5, Measurements were made using CuKa as a radiation source.

(a) Crystal orientation function fC (010), (100) Calculate H0 in the half value of the intensity distribution curve along the Debye ring of equatorial interference using the following formula,
Let it be the average value of the values obtained from (010) and (100].

fc=(180°−Ho)/180°(b) Crystal size D The apparent crystal size is calculated by scanning the equatorial line (010), (j'
oO) β' during the half value of the intensity distribution curve p 5cherre
It was determined using the following formula for r.

D=λ/βcosθ′ However, K: 8cherrer (7) Number of legs (K
=1. ! : Shiton λ: X-ray wavelength (1,5418A) θ: Diffraction angle (Bragg angle) (°J β: Half value (in radians) I32 = B12B//2 β': Actual half value (in radians) Equipment correction, perfect crystal (Si single bond in half value = 0
．． 750 (0,01509 radians) (c) Long period Lp It was determined from Bragg's formula from the inter-interference distance in the fiber axis direction of the four-point interference on the small-angle scattering photographic film, the camera radius, and the scattering angle from the geometrical conditions of the device.

6. Intrinsic viscosity IV Measure the relative viscosity η of a solution of sample 8 dissolved in 100° of orthochlorophenol (OCP) at 25°C using an Ostwald viscometer. Calculated using the following formula.

IV=0.0242η, +[L2634η1=(txd
)/("o"o) However, t and tO are the falling times of the sample solution and OCP, respectively, and d and do are the 25°C drop times of the sample solution and OCP, respectively.
is the density at

Z A sample of carboxyl-terminated leather [C0OH sample 1) was dissolved in 0-cresol 20td, and after complete dissolution, it was cooled, chloroform 40- was added, and the potential difference was satisfied with a methanol solution of NaOH.

8. Method for collecting cords from tires The cords were taken from the tires before and after running, and the attached rubber was removed with scissors and then measured.

IVXCOOH was measured by dissolving the rubber in a solvent and then removing the insoluble rubber.

Polyethylene terephthalate fibers used in the examples were manufactured by the following method.

The yarns A-D used in the examples of the present invention, and the yarns F, G, and I (A, D) used in the comparative examples.

Polyethylene terephthalate chips with intrinsic viscosity g (I V ) = 1.20 and carboxyl end groups 10 eq/10'g were prepared using an extruder type spinning machine at a polymer temperature of 5'05°C, with a pore diameter of 0.6 ttun and a pore number of 144.
It was spun using a Hall spinneret. Comparative Example E was similarly spun using a chip with a carboxyl end group of 25 eq/10 6 g.

The polyester tire cords of Examples A, D and Comparative Example E were manufactured by the following method. That is,
The polyester polymer is spun into a high temperature atmosphere of 310°C, and after passing through the high temperature atmosphere, it is immediately cooled and solidified.
The yarn is taken off at a take-off speed of 6000 to 2000 rh/min to wind up an undrawn yarn having a relatively high birefringence.

Next, the undrawn yarn is drawn by a two-stage drawing method while combining two yarns. That is, the yarn feeding o-le (F
R) and 110t: (7) Stretch in the range of 1.05 to 1.75 between heating o
It was stretched to 1.5 times with a roll (2DFL) heated to 220°C while in contact with a hot plate at 0°C, and then stretched by 1.5% with a tension adjustment roll (RRJ) at room temperature, and then wound. I took it.

The properties of the obtained fibers are as shown in Table 1. Both A and D have low Mt and low dry heat shrinkage, but Comparative Example E has a high concentration of carboxyl terminal groups.

The polyester drawn yarn obtained above has a cord structure of 1500.
D, /2, twist number 4 QT/40T/10 twist, R
After being immersed in an adhesive solution containing FL as the main component, it was dried in a dry heat oven at 150°C, then continuously stretched by 3% in a dry heat oven at 245°C, and then relaxed by 1% in a dry heat oven at the same temperature of O. It was heat treated while The residence times of the cord in the oven during drying, stretching, and heat treatment were 70 seconds, 60 seconds, and 60 seconds, respectively.

Comparative Example F was spun using a spindle with a hole diameter Q of 31JI and 480 holes, and unlike Examples A to D1 and Comparative Example E, the spun yarn was Immediately cooled and solidified with an air stream at 20℃, and then
The film was drawn at a drawing speed of 0.00 m/min, continuously passed through superheated steam heated to 250'C, stretched 2.11 times, and rolled up. The birefringence of the fiber before being drawn and drawn at io'oc+m/min was 4.0.times.10@-3, which was a relatively high value. Next, the first stage drawn yarn was heated on a hot plate at 200°C (
The film was stretched to 1.38 times while being in contact with a 210°C hot plate (length 50 crn), then heat treated to 1.05 times while being in contact with a 210° C. hot plate, and then rolled up. Total stretching ratio at this time: 3.06
The drawn yarn was drawn at a draw ratio close to the limit draw ratio of 3.16, and the obtained drawn yarn had a low elongation and a significantly high Mt.

Similarly to Examples A, D and Comparative Example E, Comparative Example G was spun in an atmosphere maintained at 310°C for 50 tM below the spinneret, passed through a high-temperature atmosphere, and then spun in an air stream at 20°C. Let it cool and solidify, then pick it up at a pick-up speed of 500 m/min.
An undrawn yarn with a low birefringence of 2.5×10 −3 was obtained. Next, the undrawn yarn was stretched 6.87 times in the first stage and 1 times in the second stage.
．． The film was stretched 5 times, then relaxed by 1.5%, and then rolled up. The strength and elongation of the yarn were high, but the Mt was also high.

The raw yarn H was drawn in the same manner as the drawn yarn G except that the undrawn yarn G was used and the second stage stretching ratio was 1.65 times.
t, ΔS1. . ℃ decreased, but at the same time Mi decreased and elongation increased.

Table 1 shows the main spinning conditions and yarn characteristics of the fibers A and H above.

Comparative Examples FXG1 and H were made into tire cords by twisting yarn, applying adhesive, and high temperature stretching heat treatment in the same manner as Examples A to D and Comparative Example E.
In addition to the above, regarding and H, Example 1 in which MDE and ΔS were changed by completely varying the stretching ratio during heat treatment during adhesive application. Seed knees were applied to the carcass to produce bias tires for trucks and buses with tire sizes 10.0-20 (tire N[L
1-8). These tires were installed on cargo trucks, and after each tire had been driven 60,000 miles, the tires were disassembled and the cord strength before and after running was compared to determine the strength retention rate. Although the tire was composed of eight carcass plies, all the codes for evaluation were taken from the second carcass ply from the inside of the tire. The results are shown in Table 1.

The code A-D taken from the tire before driving has an Mt of 25.
g/d or less and Mt/Mi is 0.50
The following values are shown, but F~HrriMt is 25g/
d, M t 7M i shows a value larger than 0.50. The strength retention rate of the tires of codes A to D after running is much higher than that of the tires Na 6 to 8 using the latter codes F and H.

Also, code E is M t , M t / M i ,
Although D T / D and DE show good values, the strength retention rate is lower than the A-D value, but this is because the C0OH is high, so thermal deterioration occurs due to the heat generated by the tire while driving. This is thought to be due to the occurrence of Also code H
In the tire N18 using the above, although Mi is low at 23.3 g/d, M t / M i shows a large value, and DT/D is low at 4.5 g/d and the initial elasticity of the cord is low. Therefore, it was destroyed while driving.

Margin Example 2 A radial tire was manufactured using four types of codes A, B, FXG, and 0+, I (, tire size 1658R-13) in the carcass ply. A steel belt was placed and reinforced. These N119 to N14 tires were installed on a passenger car, and the residual strength of the cord in the carcass was measured after 50,000 miles. Shown in the table.Mt and Mt/M as in Example-1 described above.
N19 using codes A and B where i indicates a small value
．． It can be seen that the residual strength of the cord in tire No. 10 is high. Comparing the tires of Shota Kai 12 and Nao 13, G1's M
Although t is small at 19.0 g/d, M i also becomes small at the same time, so M t
/ M i Id It shows a value of 0.50 or more like G, which is a good value for strength retention, but the residual strength is also low because the initial tension is low. On the other hand, when comparing the uniformity of the tires, N1111.12.14, which has a large code ΔS, is bad. In addition, the steering performance of the tire is the worst for NIL13, which has a large MDE (and a small Mi).On the other hand, tires with floors 9 and 10, which have a small MDE and ΔS, have good handling performance and uniformity. The value of MDE+ΔS of the tire is a5~10.5 ratio, and that of the -edge part 9.10 is consistent with these values being about 172.At the same time, the value of
For codes F to H1 used for 1 to 14, MDE and △
This shows that it is impossible to make both S values low.

The steering performance was determined based on the handling performance of the tire Na11, focusing on the steering characteristics during slalom running, with the handling performance of the tire Na11 being 100, those that were better than this were determined to be 100 or more, and those that were poor were determined to be 100 or less.

Uniformity was determined by cutting the tire and determining the arrangement of the cords in the carcass plies and the uniformity by visual inspection.

Example 6 Four types of cords of AX, BX, and FXO were applied for belt reinforcement, and a radial tire (tire size 1858R14) consisting of four belt layers and two conventional polyester cords as belt reinforcement material, tire N[ Four types of tires L15 to L18 were manufactured, and the belt cords were taken out from the tires after running 70,000 times, and the residual strength of the cords in the belt portion was measured. The results are shown in Table 4. The above tire is composed of four belt layers and two carcass layers, and the residual strength was determined by measuring the belt strength of the outermost layer.

As in Examples 1 and 2 so far, cords with small M t and M t / Mi have a high strength retention rate in belt reinforcing materials, and it is a good idea that cords in tires exhibit such characteristics. It can be seen that the lifespan of ′ is increased.

Table 4

[Brief explanation of the drawing]

The drawing shows the terminal modulus of a conventional polyethylene terephthalate fiber cord and the same cord of a tire according to the present invention. Patent Applicant Azuma Shi Co., Ltd. Company Inaka Nora (%) 1980 Momme Rei Month 1C' Day 1, Case Description 1981 Patent Application No. 109408 2, Name of Invention Pneumatic Tire 5 Person Who Amends Relationship to the incident Patent applicant address: 2-2-4 Nihonbashi Miyacho, Chuo-ku, Tokyo;
Date of amendment order Self-issued 5 Number of inventions to be increased by the amendment 0 & subject of amendment <1> Mei #IIl, page 6, line 14, ``When used'' is amended to ``using''. (2) Page 9, line 16 1-t O~as96J as "6596~1.096"
and correct it. (3) Page 11, line 13 (-+)'1''/DJ is corrected to the above-mentioned nt/nJ. (4) "Treft section" in line 6 on page 16 is corrected to "tread section." (5) On page 17, line 17, [UTM-LL type tensile tester] is corrected to ``urM-4, L type tensile tester.'' (6) On page 17, line 11, "Initial modulus of elasticity (initial tensile resistance liquid)" is corrected to "Initial modulus (initial elasticity 4 or initial tensile resistance liquid)". (7) "(Initial tensile resistance ash, Ml)" from page 17, line 20 to page 18, line 1 is divided by OII. (8) Correct "2.4X1·θ-1" in the fourth line of page 18 to "2.4X10-". 1 (9) Same page 19, line 5 [Miksphov J is corrected as “Mikephor J. αQ Same page 20, line 12 “Bl=B′′-β″゛” is changed to “β1-β″-β″゛” I corrected it. αυ On page 21, line 16, ``after addition'' is amended to ``after addition''. (2) The spinning speed (m/min) of raw yarn A rEJ in Table 1 on page 26 of the same page is “150
G' is corrected to (: S 500). O. In line 5 of Appendix No. 30, ``21 Knarling'' is corrected to ``Cornering.'' ``Fujial tire'' is corrected to ``Fujial tire formed from r carcass layer.'' Procedure. Amendment Written on July 7, 1982 by Kazuo Wakasugi, Commissioner of the Patent Office1, Indication of the case, Patent Application No. 109408 of 19822, Title of the invention: Pneumatic tire5, Name of the person making the amendment Increased by the amendment Number of inventions to be amended: 0 & Subject of amendment: Detailed explanation of the invention of Meihofu -l Contents of amendment (1) Line 6 of page 22 of the specification [Delete A to DJ. (2) Deletion of paragraph 22 of the specification Page 19, line ``Correct 6000J to r4500J. (3) Correct the spinning speed of r1500J in column E of Table 1, Table 1, page 26, to r3500J. (41, same, No. 32 The uniformity values in columns 11, 12, 13, and 14 of tires in Table 3 on page 3 are corrected to [Δ, Δ, ×, and Δ, respectively] to [×, ×·, Δ, and ×, respectively.

Claims (1)

[Scope of Claims] l A pneumatic tire having a carcass reinforced with a belt distributed inside the tread portion, wherein at least one of the belt and the carcass ply is reinforced with a polyester cord, and the polyester cord is reinforced with a polyester cord. 1. A pneumatic tire which is substantially made of polyethylene terephthalate fiber, and wherein the polyester cord in the tire satisfies the following properties at the same time. (b) DT/D ≧ 4.5 (g/d
b) 5≦M1≦25 (g/d) (c) α05≦M t / M i≦α50) a
O≦D E≦25 '(X)mt, o≦△S≦2
0(X) (However, in (a) to (e) above, DT/D is strength,
Mz is the terminal modulus, Mi is the initial modulus,
, DB represent the elongation at break and the dry heat shrinkage rate at Δ5F1177°C, and their definitions shall be in accordance with the unwritten description. 2. The pneumatic tire according to claim 1, wherein the polyester cord further satisfies the following properties 7 at the same time. (to) 2.5≦MDE56.0 (%n(t)) 4.
0≦MDE+△S≦13 (%) (However, in (f) above, M D E represents the elongation at a stress of 2.25 g/d, and the definition shall follow the description in the text.)